V. \ THE UNIVERSITY OF ILLINOIS LIBRARY , NATURAL HISTORY SURVEY 570.5 ILL V. I cop 4 'm^mims'i^m^fm'^f BjmB BiimB' Bm:B B)im.Br BmB: B'r---i\t3' ,.~r:-.'> /•'. /-x '-.. •-. - L^ ^pm ei(^S6 B)m Bm s m^mB)- ■B:%BMBMB)mBMBy ■iWB%BmBMB^l^'.B)mB; rmB e)iiB)Mie.sii(,s, \l\l-JJ.: )xB)l§iBjllxB)li^^^ 5M^^ ILLINOIS BIOLOGICAL MONOGRAPHS PUBLISHED QUARTERLY UNDER THE AUSPICES OF THE GRADUATE SCHOOL BY THE UNIVERSITY OF ILLINOIS VOLUME I Urbana, Illinois 1914-15 Editorial Committee Stephen Alfred Forbes William Trelease Henry Baldwin Ward / 7 TABLE OF CONTENTS Volume I NUMBERS PAGES I and 2 A Revision of the Cestode Family Proteocephalidae. By George Roger La Rue. With i6 plates 1-350 (Distributed November 30, 1914) 3 Studies on the Cestode Family Anoplocephalidae. By Herman Douthitt. With 6 plates 351-446 (Distributed March 8, 1915) 4 Some North American Larval Trematodes. By William Walter Cort. With 8 plates 447-532 (Distributed June 28, 1915) 732170 UNIVERSITY OF ILLINOIS BULLETIN VOL.. 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Ward, No. 33 THESIS Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Zoology in the Graduate School of the University of Illinois 1911 TABLE OF CONTENTS PAGE Introduction _ 7 Historical — 9 Synonymy _ lo Deiinitions of Families and Genera Considered ii Methods of Technique 14 Anatomy and Histology of Proteocephalids 16 Characters of Diagnostic Value 33 Key to the Better Known Genera and Species of Proteocephalidae 34 Description of Proteocephalid Species yj Proteocephalus filicoUis ( Rudolphi ) 38 P. esocis (G. Schneider) 48 P. agonis (Barbieri) 51 P. exiguus La Rue 54 P. pusillus Ward 58 P. pinguis La Rue 65 P. fallax La Rue. 70 P. neglectus La Rue „ 78 P. dubius La Rue 81 P. cernuae (Gmelin) La Rue. 86 P. percae ( Miiller ) 93 Table Showing Comparative Data on P. ocellatus and P. percae.... 106 P. longicollis ( Zeder ) 109 P. torulosus ( Batsch ) 1 18 P. macrocephalus (Creplin) 129 P. ambloplitis ( Leidy ) „ I43 P. perplexus La Rue iSi P. singularis La Rue ~ 156 P. sulcatus ( Klaptocz) 162 P. pentastoma ( Klaptocz) 165 P. fossatus (Riggenbach) 167 P. skorikowi {von Linstow) 169 P. sagittus (Grimm) 171 P. salvelini (Linton) 174 P. Cyclops (von Linstow) sp. inq I75 P. hemisphericus (Molin) sp. inq 175 P. macro phallus (Diesing) sp. inq I77 P. nematosoma (Leidy) sp. inq 177 P. salmonis-umblae (Monticelli) sp. inq I79 P. osculatus (Goeze) sp. inq 180 Taenia siwplicissima Leidy 186 Taenia belones Mullcr 187 6 iiUNOlS BIOLOGICAL MONOGRAPHS [6 PAGE Taenia pollachii Rathke 187 Choanoscolex abscisus (Riggenbach) La Rue 188 G>mparative Table of Selected Characters of Proteocephalus Species 192 ^ Description of Proteocephalid Species from Amphibia and Reptiles : Ophiotaenia perspicua La Rue 204 O. lactea (Leidy) sp. inq 208 O. filaroides La Rue „ 209 O. lonnbergii (Fuhrmann) 214 O. nattereri (Parona) 218 O. racemosa (Rudolphi) 220 O. pigmentata (von Linstow) 226 O. trimeresuri (Parona) „ 227 O. coitnettei (Barrois) „ _ 231 O. punica (Cholodkovski) „ 237 O, marenselleri ( Barrois) „ 240 O. grandis La Rue. 242 Crepidobothriutn gerrardii ( Baird) 246 Comparative Tables of Selected Characters of Species of Ophiotaenia and Crepidobothriutn 260 Oochoristica cryptobothrium (von Linstow) La Rue 268 ^ Description of Species of Monticellia Monticellia coryphicephala (Monticelli) La Rue 268 M. macrocotylea (Monticelli) _ 275 M. diesingii (Monticelli) 276 M. malopteruri (Fritsch) La Rue 277 Distribution of Proteocephalidae _ _ 281 Distribution of Proteocephalids of Amphibia and Reptilia 281 Hosts and Localities Reported for Proteocephalids of Amphibia and Reptilia _ 283 Families of Amphibia and Reptilia Harboring Proteocephalid Species _ _ 284 Hosts and Localities of Proteocephalid Species Infesting Fish and the Species of Fish Infested „ 285 Distribution of the Proteocephalids of Fish According to Continents 288 Fish Harboring Two or More Proteocephalid Species 289 Proteocephalids Occurring in Two or More Species of Fish 290 Families of Fish from which Proteocephalids are known _ 305 Life History of the Proteocephalidae ~ ™ 306 Origin of the Proteocephalidae 307 Bibliography _ 310 Explanation of Plates « _ 3^9 7] PROTEOCEPHALIDAE — LA RUE INTRODUCTION Several years ago while studying under Professor Henry B. Ward at the University of Nebraska the writer began an investigation of a <;estode parasitic in Ambly stoma tigrinum (Green). That investigation resulted in a paper (La Rue 1909) in which a number of points in the anatomy of Proteocephalids were cleared up and certain problems were outlined for investigation at an early date. In the meantime the writer became interested in the large number of Proteocephalids which Pro- fessor Ward had secured by work in the field and by exchange. The writer had also made some collections. A preliminary study of the available material by the writer was convincing to Professor Ward that a more complete and comparative study of the group was desirable and that the results of such a study would prove of value to helminthologists, not only of America but also in Europe. Such a study seemed more desirable since but two comparative studies of the group had been made in more than fifteen years, the first by Riggenbach (1896) mostly on the species infesting fish, and the second by Schwarz (1908) wholly on the species infesting snakes and reptiles. The fact that very little had been done on the genus by American investigators furnished an added incentive to undertake the work. At Professor Ward's suggestion and under his direction the writer "undertook an investigation of the genus which would be comprehensive in scope and at the same time comparative. For this purpose Professor Ward augmented the material already at hand by securing the loan of alcoholics and prepared slides from several European and American investigators and from the collections of the Smithsonian Institution and the Bureau of Animal Industry at Washington. Unfortunately specimens of certain material could not be secured either because it had been lost or because it could not be removed from the collections. The lack of some of this material has caused the writer to change the plan of the paper somewhat. Instead of making a fresh study of each species it has been necessary in describing certain species to depend on the data secured from the literature. These data have been recom- liined and quotations have been made, sometimes quite extended, while 8 ILLINOIS BIOLOGICAL MONOGRAPHS [S original drawings which were found useful in presenting the characters and structures of the species have been copied and used in the new account. Possibly it may seem that a consideration of these species might have been omitted without apparently having great effect on the value of the work. The writer found however that serious errors had been made in determination and upon these mistaken determinations identification of other species had been made dependent. The only way of escape from the tangle was to consider every species in the family. In order that the work might be of more value to many of the American investigators to whom large numbers of the older works of the European writers are unavailable and for the purpose of comparison large extracts from these older writings have been quoted verbatim. For these reasons also the number of drawings copied is larger than at first glimpse seems necessary. The writer has been compelled however to omit because of lack of space many extracts and many drawings which would add to the value of the work. In working over the large literature on the subject an attempt was made to secure every important paper. Some less important papers are known to have been omitted. Thanks are due to the following investigators who at the request of Professor "Ward so kindly sent prepared slides or alcoholics from their valuable collections for study and comparison : Professor Fritz Zschokke, University of Basle, Professor Corrado Parona, University of Genoa, Professor Max Braun, University of Konigsberg, Professor K. M. Levander, Helsingfors, Finland, Professor Anton Collin, University of Berlin, Professor A. E. Shipley, Christ's CoUege, Cambridge, Professor Fr. Sav. Monticelli, University of Naples, Professor 0. Fuhrmann, Uni- versity of Neuchatel, Dr. C. W. Stiles, Hygienic Laboratory, Washing- ton, D. C, Dr. B. H. Bansom, Bureau of Animal Industry, Washington, D. C, Professor Edwin Linton, Washington and Jefferson College, Professor A. J. Smith, University of Pennsylvania, Professor L. T. Hankinson, Charleston, 111. Mr. E. G. Davis of Lincoln, Nebr., and Mr. Herman Douthitt of Sulphur, Oklahoma, have also very kindly furnished material for study. Thanks are due Mr, S. Fred Prince for re-drawing many of the figures from other works and for making my pencil sketches into the finished drawings. To the United States Bureau of Fisheries and to its corps of scien- tific workers I am indebted for encouragement and assistance in many ways, especially in securing valuable material from various sources. To Professor Henry B, Ward my sincerest thanks are due for the use of his extensive collections, for the use of his library, and also for securing for my use many rare specimens and rare books. His interest and co-operation have given me the inspiration to complete the work. 9] PROTEOCEPHAUDAE — LA RUE HISTORICAL DATA Rudolphi (1808-10) collected together the results of the systematic labors of helminthologists up to that time. His work is very complete and in it are to be found the diagnoses, synonymy and descriptions of the species of this genus that were known at that time. These species are included in the genus Taenia Linnaeus 1758. It is to be noted that Rudolphi renamed certain of these species which had been previously established by other investigators. Later Rudolphi (1819) brought down to date a summary of the investigations of preceding helmin- thologists. Some of the early investigators, other than Rudolphi, who reported species now included in the genus Proteocephalus, were Goeze, 0. F. Miiller, Pallas, Gmelin, Batsch, Schrank, Zeder, Bloch, and Froelich. Many of their descriptions and diagnoses were very short. Only a few were accompanied by drawings. It is needless to say that the works of these early investigators are almost entirely concerned with the study of external characters. There were no more important works which have to do with this group of cestodes until the time of Dujardin (1845) and Diesing (1850). These investigators listed several new species and new host species. Investigators up to the time of Monticelli (1891) with the excep- tion of Weinland (1858) considered this group of fish cestodes to belong to the genus Taenia. The latter author proposed the name Proteocepha- lus which will be discussed later and the former proposed the name Tetracotylus. It was von Linstow (1891) who first pointed out that the fish species made up a closely related group within the genus Taenia. He made the first careful study of one of the species of this group. Monticelli (1891) made a careful study of the group and pointed out several misinterpretations relating to the genital organs. He first showed the true relationships of the organs in the interovarial space. His work was largely based on Taenia coryphicephala with which he compared other species. In all he listed 20 species belonging to his genus Tetracotylus. Of these species some were from snakes. For a more complete discussion of that work see the description of Monticellia (Tetracotylus). Since this work of Monticelli, Lonnberg (1894) proposed the genus Ich thy ©taenia and in this genus many species have been included. The range of hosts includes amphibians, snakes, lizards, and all the larger groups of freshwater fish. 10 ILLINOIS BIOLOGICAL MONOGRAPHS [10 In 1899 Monticelli recognized that Tetrabothrium gerrardii Baird, a parasite of the Boidae, belonged in this family of cestodes but that it should be separated from the species of Proteocephalus, and for this species he proposed the genus Crepidobothrium. In 1903 von Linstow proposed the genus Acanthotaenia to include a spiny headed Proteo- cephalid from Varanus. This genus was later emended by Johnston {1909) who placed three other species in it, all from Varanidae. It has been found necessary to restrict the genus Proteocephalus by removing from it the species of amphibian and ophidian Proteocepha- lids. These make a fairly homogeneous group for which the writer proposed the name Ophiotaenia La Rue 1911 with Ophiotaenia perspicua Xia Rue as the type species. SYNONYMY Weinland (1858:53) proposed the genus Proteocephalus and named as its type Taenia ambigua Dujardin. Taenia filicollis and Taenia dis- par were also included under this genus. Lonnberg (1894:801-803) proposed the generic name Ichthyotae- nia and listed as members of this genus: 'Z. filicollis Rud., I. ocellata Rud., 7. longicollis Rud., I. torulosa Batsch, and /. coryphicephala Mon- ticelli. Since Lonnberg named I. filicollis first in his list that name is to be considered the type of his genus and has been so designated by Hall (1910). Thus he made Ichthyotaenia a synonym of Proteocepha- lus unless T. filicollis Rud. is genericaUy different from T. ambigua (Dujardin). On this point Railliet (1899) says: "Comme cette espece (Taenia ambigua Duj.) re^tre nettement dans le genre Ichthyotaenia il est evident que le premier nom (Proteocephalus) doit etre repris." The validity of the names Proteocephalus Weinland or Ichthyotaenia Lonnberg then depends on the species T. ambigua Dujardin and T. filicollis Rud. The first named species was fairly well described and measurements of diagnostic value were given by Dujardin (1845). This species has since been well described and figured by G. Schneider and later by the writer using Schneider's material which agrees almost per- fectly with Dujardin 's description of T. ambigua. Taenia filicollis Rud. is not a synonym of Taenia ocellata Rud., and consequently, of Taenia percae Miiller, as Kraemer, Riggenbach, Bene- dict, Railliet, and others have thought. That belief was founded on a mistaken identification by Kraemer (1892). Since Dujardin (1845) there have been but few records of examinations of Gasterosteus. One of these records is by Lonnberg, another by Schneider. They examined Oasterosteus pungitius, while the type host of T. filicollis is Gasterosteus 11] PROTEOCEPHAUDAE — LA RUE 11 aculeaius and so far as the writer can discover there have been almost no records of collection of parasites from that host since Dujardin. The diagnoses of Taenia filicollis much resemble those of Taenia ambigua. Dujardin however evidently considered these two species as different for he records both. At the present time but a single species is well known from Gasterosteous, viz, Proteocephalus ambiguus (Dujardin). yyThe writer considers however that P. ambiguus is identical with P. filicollis (Rud.) and hence the genera Proteocephalus Weinland and Ichthyotaenia Lonnberg being based on the same species are synonyms and the earlier name should be retained. The synonymy of the name Tetracotylus Monticelli (1891) has not yet been discussed. This name was based on the description of Taenia coryphicephala altho Monticelli failed to designate it as the type species. Braun (1894-1900) stated that this genus was based on T. coryphiceph- ala and this action was considered by Hall (1910) to be tantamount to the designation of a type. Braun regards Tetracotylus to be a syno- nym of Ichthyotaenia which makes it a synonym of Proteocephalus pro- vided that the type of Tetracotylus belongs in the same genus with Taenia filicollis (Rud.), the type of Proteocephalus. That Tetracotylus coryphicephala does not belong to the same genus with Proteocephalus filicollis has been shown by the writer in the descriptive study of the former species (vide infra). Moreover the writer has shown that this form does not belong with any genus of cestodes at present known. It is then necessary to examine into the status of the name Tetracotylus as a generic name for Taenia coryphicephala. The availability of Tetracotylus has been questioned because of the name Tetracotyle Filippi (1854), These two names are not spelled alike and are therefore not homonyms, Braun (1894-1900) suggests that Tetracotylus has been used for Tetracotyle. If such improper use has been made of the former name prior to the time when Monticelli pro- posed it then Tetracotylus has been rendered unavailable. The writer has not been able to find evidence of such improper use, yet because of ^Braun's statement of the fact and his objection to the use of the name ^Xwthe writer has proposed the name Monticellia in honor of Professor Mon- < ticelli who has done so much for our knowledge of this group, as a name to take the place of the invalidated Tetracotylus, The type of this genus is Monticellia coryphicephala (Monticelli), The genus is to be defined thus : Monticellia La Rue : Head small, globose, without folds or lappets of tissue encircling suckers. Suckers sessile and without accessory areola. No rostellum. Testes, vitellaria and uterus entirely outside of the inner longitudinal muscle- sheath. Vitellaria composed of scattered follicles which form broad 12 ILLINOIS BIOLOGICAL MONOGRAPHS [12 lateral fields. Testes numerous, forming a single broad dorsal field be- tween vitellaria. Uterus ventral, with many lateral pouches. Genital pore marginal, irregularly alternating. Ovary bilobed and situated partly within and partly outside the inner muscle-sheath. Sexual organs in general as in Proteocephalidae. In Siluridae. The type of the genus is Monticellia coryphicephala {Tetracotylus coryphicephala Monticelli). The position of this genus in the order Tetraphyllidea is difficult to determine. It apparently does not belong to any of the families as now defined therefore the writer suggests for it the family name Monticelli- dae with the following characters: Head small. Suckers sessile and without accessory areola. Internal anatomy as in the type genus Monti- cellia. There still remains the question as to whether the name Proteo- cephalus is available. That name has been objected to on account of the name Proteocephala suggested by de Blainville (1828) for a cestode family. These two names are not homonyms and it is agreed that the use of a name to designate a family does not invalidate it for use subse- quently as a generic name. The writer therefore retains the name Proteocephalus Weinland as the generic designation for the genus of which Taenia filicollis Rud. is the type. Having determined that Monticellia coryphicephala (Monticelli) does not belong in the family Proteocephalidae because of its peculiar organization, it is necessary to redefine that family thus: Family Pro- teocephalidae: Heads small. Suckers sessile and without accessory areola. Fifth sucker functional, vestigial, or lacking. No rostellum. Genital organs in general as in other Tetraphyllideans. Genital pores marginal, irregularly alternating. Vitellaria lateral, follicular, follicles closely grouped about a central conducting tubule. Ovary bilobed, posterior. Oocapt, ootype, shell gland, uterine passage present. Uterus with lateral outpocketings and one or more preformed ventral uterine openings. Vitellaria, testes, ovary and uterus within the inner longi- tudinal muscle-sheath. Habitat: In fresh-water fish, amphibia, and aquatic reptiles. In this family belong the following genera which are here defined: (1) Proteocephalus Weinland 1858 "With characters of the family. Head globose or conical, flattened dorsoventrally. No rostellum. No spines or hooks. No fold of tissue encircling base of head or enfolding suckers. Suckers circular or oval. Fifth sucker functional or vestigial, rarely lacking. Testes in a broad field between vitellaria. Parenchyma with close meshes. Musculature well developed. Eggs with three membranes. Habitat : In fresh-water Ml. 13] PROTEOCEPHAUDAE — LA RUE 13 Type species: Proteocephalus filicolUs (Rudolphi) Syn. : Proteocephalus amhiguus (Dujardin) (2) Choanoscolex La Rue 1911 With characters of family. Head conical with a fold of tissue at the base partially covering suckers. No rostellum, no hooks, no spines. Oenital organs as in Proteocephalus. Habitat : In Siluridae. Type species: Choanoscolex ahscisus (Riggenbach). (3) Corallohothrium Fritsch 1886 "With characters of family. Scolex with four suckers situated on the flat anterior face of the head. Many irregular folds and lappets of tissue about margin of anterior surface; may enclose suckers as in a corolla. No rostellum. No hooks nor spines. Neck broad, short. Habi- tat : In Siluridae. Type species: Corallohothrium solidum Fritsch. (4) Crepidohothrium Monticelli 1899 With characters of family. Head large, swollen, pjrramidal, tetrag- onal, unarmed. Suckers large, inversely cordate, posterior margin in- terrupted and re-entrant into sucker cavity. Fifth sucker vestigial. Oenital apertures marginal, irregularly alternating. Vaginal opening dorsal to cirrus pouch. Vagina anterior or posterior to cirrus-pouch. Testes in two lateral fields anterior to ovary. Habitat: In Boidae, South America. Type species: Crepidohothrium gerrardii (Baird) (5) Acanthotaenia von Linstow 1903 With characters of family. Scolex rather small. With four rounded suckers. Apex of head conical in which may be situated a vestigial fifth sucker. No rostellum. Cuticula of head and anterior part of body cov- ered with minute spines or bristles. Segmentation indistinct. No over- lapping of segments. Testes in two lateral fields anterior to ovary. Ovarian lobes may be branched. Vagina anterior or posterior to cirrus. Habitat: In Varanidae and Hylidae. Type species : Acanthotaenia shipleyi von Linstow (6) Ophiotaenia La Rue 1911 With characters of family. Head globose or somewhat tetragonal. No rostellum. No hooks or spines. Suckers circular or oval, with mar- gins entire. Fifth sucker vestigial. Neck usually long. Testes in two long lateral fields anterior to ovary. Vagina anterior or posterior to cirrus-pouch. Ovary bilobed, flattened, sometimes alate. Parenchyma V 14 ILLINOIS BIOLOGICAL MONOGRAPHS [14- with fine meshes. Musculature weak. Habitat: In aquatic snakes, Cro- talinae, Colubridae, Elapinae and Amphibia. Tyj>e species : Ophiotaenia perspicua La Rue 1911. In the descriptive section the greater number of species of the above named genera have been described, with exception of species of Acanthotaenia and Corallobothrium. It has been impossible to write up the descriptions of certain species inquirendae of which no material could be obtained, and for which only very meager descriptions have ever been written. It is hoped that these may be properly considered at a later time. METHODS OF TECHNIQUE The following methods have been used by the writer in the work on this group of cestodes. To a large extent they may be used with success on all groups of cestodes although it should be understood that certain methods which give admirable results with the relatively small and thin cestodes here dealt with will not give equally good results if used on the large forms such as Taenia. The larger forms were picked out of the intestinal contents, care being taken to free the head if the worm was attached to the mucosa. These were then repeatedly dipped in the killing solution until the worm ceased to contract. The worm was allowed to lie for 15 minutes to 2 hours in the same fluid. Metallic instruments are to be avoided if cor- rosive sublimate solutions are used for fixation. When the smaller worms were encountered the whole intestine slit open was placed in a small quantity of physiological saline solution in a bottle which was then shaken vigorously for about 3 minutes, the killing fluid was added and the whole then shaken for one half minute. This is according to the method of Looss. The fixative was permitted to act 3 to 10 hours. The killing fluids used were hot 5% solution of formaldehyde, and hot or cold saturated aqueous solution of corrosive sublimate to which was added glacial acetic acid to make 1 to 2%. Some other fluids were tried but nothing gave better results for the purposes of this study than the corrosive acetic mixture used hot or cold. For most of the worms the cold solution was preferable to the hot which sometimes gave rise to artifacts if used at too high a temperature. In no cases were the worms stupefied before killing. The usual methods were used for hardening and dehydrating. Speci- mens were usually preserved in 85% alcohol after running up through. 15] PR0TE0CEPHAL1DAE~LA RUE 15 the grades. Sometimes after the corrosive acetic fixation 5% formalin was used for a preservative with uniformly excellent results. Sections were cut 5 to 10 micra thick for the study of histological detail and 20 micra when grosser morphological details were sought. The sections were stained with haematoxylin mixtures, either Delafield's haematoxylin or Mayer's haemalum, and decolorized in the manner approved for these stains. Methods of staining in toto followed by sec- tioning were used with great success at times. For this purpose Ehr- lich's acid haematoxylin much diluted with 50% alcohol gave the best results. For a contrast stain eosin in 95% alcohol was used on the sec- tions. Acid fuchsin also in 95% alcohol was sometimes used effectively. Preparations in toto were much used and were found to be of great value in mapping out the relationships of the organs of the proglottids. Frequently these methods showed everything to be desired except the histology of the organs. In some cases even histological details were well revealed by these methods. The stains which were tried for staining in toto were Mayer's paracarmine, Grenacher's borax carmine, some alcoholic cochineal mixtures, Mayer's haemalum, Delafield's haematoxy- lin, and Ehrlich's acid haematoxylin. None of the carmine or cochineal stains were very successful for none of them show the boundaries of cestode structures sharply. The parenchyma in which the genital organs lie always retained too great an amount of these stains to permit a clear view of the genital organs themselves. The haematoxylins, however, usually gave wonderfully clear, sharp pictures of the genital organs. It was at times possible to work out such minute structures as vasa efferentia almost in their entirety from such preparations in toto. The three haematoxylin stains were found to be about equally good. In using these stains it was the practice to dilute the stain with the proper diluent. Relatively large quantities of the diluted stain were used for each lot of material. The stain was permitted to act over night (10 to 15 hours) at room temperature. The excess of the stain was then removed by washing in distilled water and the tissue passed through the grades of alcohol to 70% where it was decolorized rapidly by adding hydrochloric acid to make a 0.5 to 1.0% solution. The object was to remove the stain from the peripheral tissues at a rapid rate and mean- while leave the stain in the deeper lying tissues. In this method the duration of the acid bath is usually short depending upon the size of the piece and the character of the stain taken by the tissue, and upon the character of the tissue itself. In general it is desirable to decolorize until a light reddish blue stain remains and until many of the internal structures can be distinguished while the tissue is still in the alcoholic medium. When in the judgment of the operator the proper stain is 16 ILLINOIS BIOLOGICAL MONOGRAPHS [16 attained the tissues are placed in neutral alcohol and then into 70% alcohol rendered slightly alkaline by the addition of a few drops of an aqueous solution of sodium carbonate. Preparations were not flattened but were straightened out on a slide and over this was placed another slide which was supported by strips of paper of such a thickness that little or no pressure was exerted on the specimen by the slides. Dehydration and clearing were accomplished while the preparation was thus kept straight. Xylol and cedarwood oil were used as clearing agents. Preparations were mounted in balsam. The methods outlined above yielded very satisfactory preparations for the study of these cestodes and they have also been used by the writer on other cestodes and on trematodes with great success. It is noteworthy that the carmine stains give beautiful preparations of trem- atodes in toto but fail almost entirely for cestodes. For the cestodes these stains fail because they do not sharply and clearly outline the sexual organs as they do in trematodes though not better than do the haematoxylins. In the judgment of the writer the use of the carmine stains on cestode material has been responsible for many errors in the interpretation of cestode structures. ANATOMY AND HISTOLOGY OF PROTEOCEPHALIDS This section deals in a very general way with the anatomy and histology of the Proteoeephalidae, placing emphasis on the usual char- acter of the structures encountered and at times calling attention to variations in this general plan. In the descriptive part of the work the ordinary histological details and many of the anatomical details of lesser importance have been omitted or mentioned in only a casual way. "Whenever the character of a structure has departed from the usual the fact has been noted in more or less detail. The cestodes of the family are constructed on a uniform plan which has been thoroly discussed by Monticelli (1891), Kraemer (1892), Rig- genbach (1896), Benedict (1900), Schneider (1905), Schwarz (1908), and La Rue (1909). Some new points are brought out in the present paper. The histological structures of these cestodes have been pretty well worked out prior to the present time. Von Linstow ( 1891 ) , Monti- celli (1891), Kraemer (1892), and Riggenbach (1896) did pioneer work on the histology of the group. Riggenbach (1896) and Benedict (1900) made very careful and accurate studies of the histology of certain spe- cies of fish Proteocephalids and were able to clear up some of the earlier misconceptions. No careful work on the histology of the amphibian 17] PROTEOCEPHALIDAE — LA RUE 17 Proteocephalids was made until the work of the writer (La Rue, 1909) on Ophiotaenia (Proteocephalus) filaroides. Subsequent work on the histology of the eestodes of snakes has shown but little new, altho it must be admitted that only little has been done on the group. The scolex is usually of small size and rather inconspicuous. Among the fish Proteocephalids the heads range in size from a little more than 0.1 mm. in breadth to about 1. mm., tho in at least one species, P. sulca- ius, the breadth of this region attains as much as 1.75 mm. Among the amphibian and reptilian Proteocephalids the heads range from about 0.2 mm. to 1,75 mm. in breadth. In general the head is not sharply delimited from the neck, which may be of nearly equal width or in exceptional cases even wider for a short distance than the head. In form the heads show considerable variation. They are usually more or less globose or conical, and somewhat flattened dorsoventrally. In a few cases the head inay present a more or less flattened tetragonal anterior face. The surface of the heads may be smooth or marked by shallow or deep grooves between the suckers. As a rule the heads have no folds or lappets of tissue about the suckers or on the anterior face. Such structures are found, however, in Corallobothrium and to a more limited extent in Choanoscolex. The special characters of the heads of each species are taken up in the descriptive part of the work. The heads of Proteocephalidae and Monticellidae differ from those of other families of Tetraphyllidea in that the suckers are sessile, and have no accessory areola. Even when the head is deeply furrowed the sucker never has the appearance of having a stalk. Suckers may be prominent or inconspicuous and so may influence the general appearance of the head. A rostellum is unknown among the species of this family, altho certain species have been erroneously reported to have such an organ. It is possible, tho not probable, that some species of Acanthotaenia have a rostellum. Some of these species have long apical prominences on the head, but except for the elongation of this apex and the presence of cuticular spines there is no evidence for considering this structure to be a rostellum. The spines are not hooks but are cuticular structures which may extend over the anterior part of the body. Neither elongated tip nor cuticular spines are good criteria of the presence of a rostellum. To determine the presence of a rostellum one should look to the inner structure of the apex, its musculature and protrusibility, and to the origin of this rostellum-like tip. In the tip of the heads of many species which do not possess a functional fifth sucker there has been found a peculiar structure consisting of massed cells and sometimes a few mus- cular elements. This structure has been considered to be a rudimentary 18 ILLINOIS BIOLOGICAL MONOGRAPHS [18 rostellum. Such a supposition, however, is incorrect, for in its devel- opment it is a fifth sucker. A more complete discussion of this rudi- mentary or vestigial fifth sucker is given under the proper caption (vide infra). ' All species are provided with four suckers and some with an apical fifth sucker in addition. The latter may be either functional or vesti- gial. The four suckers are sessile, prominent, or inconspicuous cup- shaped organs which are usually situated on the broadest part of the head or just anterior to the broadest zone. In Corallobothrium the suckers are situated on the flattened anterior face of the head. The suckers do not possess accessory areola nor are they provided with hooks in their cavities or on their margins. Acanthotaenia may have cuticular spines within the sucker cavity. Suckers are usually rounded or oval in outline and may have deep cavities. The margin is usually entire but is at times interrupted. Some peculiar cases occur : Proteocephalus Cyclops has suckers pointed at the posterior end. The suckers of P. singularis (Fig. 25) are flat, thin and weakly muscled and have a peculiar upturned point at the anterior margin. The deep grooves be- tween the suckers of this species cause these organs to stand out promi- nently. Crepidobothrium gerrardii (Figs. 12, 13, 33, 34, 123, and 124) likewise has peculiar suckers in that each has an interrupted lower margin which forms a point re-entrant into the sucker cavity. Deep grooves between the suckers give the head a lobed appearance and cause the suckers to be prominent. Proteocephalus osculatus (Fig. 162) has a fifth sucker which is said to be covered with minute spinelets. The suckers of some of the Acanthotaenia are covered with minute spinelets. It is deemed unnecessary to enter into a discussion of the histologj" of the suckers of this group. Benedict (1900), Kraemer (1892), and La Rue (1909) have discussed this subject in detail. A functional fifth sucker situated at the apex of the head is present in many species of Proteocephalus but is not known among the other genera of the family. Other species of Proteocephalus, Ophiotaenia, Crepidobothrium, and Acanthotaenia are known to possess a structure which the writer (1909) called an end-organ and which Johnston (1909 et seq.) has called an apical muscle-plugy^ther species of Proteocepha- lus and all known species of Corallobothrium and Choanoscolex do not possess this structure or the functional fifth sucker while some species of Proteocephalus and Ophiotaenia have not been investigated for it. The writer has now determined that this organ is a vestigial fifth sucker. The fifth sucker when functional is usually smaller than the others and it possesses all the histological structures of other Proteocephalid suckers. The basement membrane and the muscles have the same relations as in other suckers. 19] PROTEOCEPHALIDAE — LA RUE 19 The vestigial fifth sucker in the adult head is represented by a mass of cells or of nuclei and at times a few fibers surrounded by a basement membrane. It is entirely sunken into the tissues of the head and has lost all connection with the exterior. An examination of this structure in an adult head yields no clue to its probable origin, but if heads of plerocercoids of a species which has this structure in the adult be exam- ined it is seen to be a degenerate fifth sucker. In the plerocercoid this degenerating fifth sucker has a sucker cavity communicating with the exterior. It has basement membranes and a full complement of muscles altho some of the muscles may be somewhat displaced and undergoing atrophy. The origin of this structure has been worked out in some detail for Ophiotaenia filaroides and the results are given in the descrip- tion of that species. Its structure is illustrated by drawings which are reproduced here (Figs. 27, 28). The structure of the adult organ was given in the writer's paper on this cestode (La Rue 1909). A vestigial fifth sucker which has not reached such a state of degeneracy as is found in many of the species occurs in the head of Crepidohothrium gerrardii. In this species the sucker tho so greatly reduced in size as to be overlooked in an examination of toto prepara- tions still retains its cavity which is yet in connection with the exterior through a small pore. The sucker is surrounded by a basement membrane and it shows some traces of muscles altho the material studied was too poor to make a good histological study. A more complete description of this vestigial sucker is to be found in the description of Crepidohoth- rium gerrardii. Its structure is delineated in figure 42. In his descrip- tion of these vestigial structures found in O. filaroides and in C. gerrar- dii the writer has conclusively shown that the organ under discussion is a vestigial fifth sucker and not a vestigial or rudimentary rostellum. It seems highly probable that similar structures found in other species of the group will prove to be vestigial fifth suckers. The writer can see no reason for assuming that this structure is a rudimentary rostellum. So far as known a well developed rostellum does not occur among the Tetraphyllidea but is characteristic of many species of Cyclophyllidea. Unless an apical sucker is a transitional stage in the development (phylogenetie) of a rostellum the writer sees no reason for regarding this vestigial fifth sucker as a rudimentary rostel- lum. The knowledge concerning this structure is incomplete and studies of developmental stages of Proteocephalid species possessing vestigial or functional fifth suckers should be made in comparison with similar de- velopmental stages of species of Calliobothriura and Anthocephalus which according to Lang (1881) and Monticelli (1888) have certain rudimentary structures that seem to be like the oral suckers of trema- 20 ILLINOIS BIOLOGICAL MONOGRAPHS [20 todes. Likewise a study should be made of certain species of Cyclophyl- lidea which are known to possess a rudimentary or a vestigial rostellum. No definite solution of this problem can be reached without such a com- parative study. Data as to the presence or absence of the fifth sucker in species of the group, whether functional or vestigial, is to be found in the tables of the principal characters of the cestodes of this family. The nervous system is made up of a nerve ring which occurs in the neighborhood of the suckers and one pair of main lateral nerve trunks in the strobila. As described by the writer (1909) for Ophiotaenia fila- roides the nerve ring is somewhat octagonal in shape and at its corners nerve processes extend out to the suckers. From the ring main trunks extend back into the strobila. In the strobila a single pair of main lateral trunks may be seen just within the lateral fields of the muscle sheath. No accessory nerve trunks have been made out by the writer. In Ophiotaenia filaroides the nerve trunk passes dorsal to the cirrus and the vagina. In all species the neck is a more or less poorly defined unsegmented region between the head and the segmented part of the strobila. This region may be several millimeters long in certain species while in others it is said to be entirely lacking or may be no more than 0.3 to 0.5 mm. long. It is usually narrower than the scolex tho in exceptional cases in which the neck muscles may be unduly contracted the neck is broader than the scolex. Much confusion has arisen over the statements of the older investigators who described the neck of certain species as being long or very long without, however, giving measurements. These adjectives are relative terms. If the cestode is small, 0.5 to 1 mm. broad and 20 to 100 mm. in length, a neck which is 1 to 5 mm. long seems long or very long. A neck of that length on a cestode as large as Crepidohothrium gerrardii which is several millimeters broad and many centimeters long would be called short. In this species an unsegmented region 0.5-1 mm. long is ignored by some authors and the specimen is reported as having no neck. It is essential that actual measurements of the unsegmented region be made. For this purpose stained specimens are necessary be- cause unstained specimens will not show segmentation plainly and also because external wrinkles or folds may simulate segmentation. In re- cording measurements of the neck the writer takes the length from the point of narrowing behind the suckers to the first evident traces of in- ternal segmentation. In a few species another system has been found necessary but in these cases the method of measuring has been stated. The breadth given is the narrowest place in the unsegmented region. The segmented part of Proteocephalids varies greatly in length, breadth, and thickness. In some species the strobila is small, being not 21] PROTEOCEPHALIDAE — LA RUE 21 more than a few millimeters long and less than 1 mm. broad, while in others it may attain a length of 60 or more centimeters and an extreme breadth of 2 to 4 mm. Such extreme size is infrequent even for the large species. Many of the species of Proteocephalus are thick and fleshy while a few of them are thin and flat. So also are the known species of the family Monticellidae. Segmentation may be evident or obscure. Perhaps in no species is it as evident as it is in some species of Taenia. The proglottids are usually without sharp posterior angles and they are attached along their entire width. Transverse intersegmental furrows if present are shallow. The youngest proglottids are very indistinct and are distinguished in stained preparations as faint cross bands of alternate dark and light. These are darkly stained areas of rapidly differentiating parenchyma alternating with the unstained future septa. Almost without exception the young proglottids are much broader than long. The reverse of this is true only when the anterior part of the body is in an extremely attenu- ated condition. As the young proglottids develop they increase in length and breadth, tho the length usually increases more rapidly than the breadth. The transition from young to mature proglottids is grad- ual. Mature proglottids are those in which the sexual organs have at- tained maturity and egg production is about to begin or may just have begun. Such proglottids are usually broader than long or quadrate. The length is much greater than in the young proglottids. Mature prog- lottids are the best ones in which to study the greater part of the genital system tho of course a study of the uterus must be made from the ripe proglottids. Those proglottids in which egg production is well along or complete are spoken of as ripe proglottids. The uterine pouches are full of eggs and the ventral openings are preparing for their discharge. Ripe proglottids are frequently longer than broad tho the reverse is not un- common. They are normally considerably larger than mature proglot- tids. In them the vitellaria and testes may be greatly reduced in size or almost obliterated by the great mass of eggs in the uterine pouches. An end-proglottid is frequently present. This should be defined as the first proglottid to be differentiated from the growing zone of the neck. It still retains certain of the characters of the posterior end of the plero- cercus which is not lost in the passage of the young tapeworm through the stomach of the host. It is pointed posteriorly and has at the tip a median excretory pore through which the excretory products are dis- charged. Just anterior to this pore, in some species, is a contractile bladder. In the species examined by the writer a number of end-proglot- tids have been found; some of these contained eggs and so are to be 22 ILLINOIS BIOLOGICAL MONOGRAPHS [22 considered as functional. Since ripe proglottids are shed after or about the time that the eggs are ripe one frequently encounters strobilas which lack the end proglottid. The loss of this proglottid is not to be consid- ered as a special character, for it is common to many eestodes outside the group. Two pairs, dorsal and ventral, of main lateral excretory trunks ex- tend through the strobila. Of these the ventral vessels are the larger. Some additional longitudinal vessels have been described by von Linstow (1891) in Proteocephalus longicollis. It seems probable that he saw the cut ends of branches and anastomoses. Some species have a commissural vessel connecting the ventral excretory vessels at the posterior end of the proglottid. It has not been noted in other species. In the neck region and throughout the strobila many small branches arise from the ventral vessels and some also from the dorsal vessels which pass to the surface of the worm where they discharge to the exterior through a small pore. These openings occur more fiV^uently on the ventral surface but may be found on the lateral edga^ In most species they are irregularly dis- tributed but in Corallohothnum lohosum Riggenbach (1896) found that they regularly came to the exterior at the posterior comer of the pro- glottid. This finding has not been supported by subsequent work on other species. In the head and the anterior neck region there are numerous coils of vessels and anastomosing branches of the same which extend well into the tip of the head. These coils lead back and are con- nected with the main lateral excretory trunks. At the posterior end of the worm the excretory vessels discharge, if the end-proglottid is pres- ent, through a common excretory pore (Fig. 51). Just anterior to this pore and discharging thi;ough it is sometimes a pulsatile bladder which is most readily seen in the plerocercus. The flame cells at the ends of minute vessels which discharge into the main vessels or into the larger branches are situated in the medullary parenchyma not far from the main excretory vessels. They have not been found in the cortical paren- chyma nor in the mid-field of the proglottid. Their distribution in Ophiotaenia filaroides and Proteocephalus amhloplitis has been thoroly worked out (La Rue 1909). The cuticula and the subcuticular structures are scarcely worthy of discussion here for in details of structure they do not differ from other eestodes. In the Acanthotaenia alone are there special features of the cuticula to which attention should be called. Here the cuticula is thrown up into minute cuticular spines which are too minute to be called hooks or booklets. This condition is most prominent on the head and neck but may also occur to a smaller extent over the cuticula of the entire body. These features have been emphasized by von Linstow (1903) and John- 23] PROTEOCEPHALIDAE — LA RUE 23 stou (1909, 1911, 1912a). Outside of this genus the only other species to have cuticular hooklets or spines is Proteocephalus osculatus, in which they are reported to have been found on the apical fifth sucker. The parenchyma resembles that of other cestodes but is more loose than in the Cyclophyllidean cestodes which the author has examined. In the parenchyma the cell outlines are indistinguishable but there are numerous structures present which look somewhat like minute fibrillae. Large fat spaces are usually visible in the prepared sections and some- times in toto preparations. In 0. filar oides studied by the author (1909) the fat spaces are spheroidal or ovoidal in form and have a dimension of 0.03 to 0.045 mm. Similar spaces have been observed in other species of the family. They are smaller in the fish cestodes studied and larger in the snake and amphibian cestodes. The fat of fresh cestodes or of those recently killed in formol is readily stained by osmic acid solutions or by an alcoholic solution of Sudan III. Other specific fat stains have not been tried. The character of the parenchyma affects the staining prop- erties of the cestodes. Those cestodes having a loose parenchyma make much better toto preparations than do those which have the dense parenchyma. In general the parenchyma of the group of snake Proteocephalids is a more open, looser network than that of the fish Proteocephalids. There is more of the fibrillar structure present in the parenchyma of the latter than of the former. Whether this character is correlated with differences in environmental stimuli is not known. Perhaps the appear- ances of the parenchyma of cestodes can be explained as are the appear- ances of the connective tissues of higher animals. If this be true then it is evident that the closer woven texture of the parenchyma in fish cestodes is indicative of more frequent stresses and strains placed upon the cestode by the activity of the host or by the movement of ingested materials through the alimentary tract. The sub-cuticular muscles resemble those of other cestodes. The circular and longitudinal fibers are not strong. Within the layer of sub- cuticular cells of the strobila there is a layer of longitudinal muscle fibers which separates the cortical from the medullary parenchyma in which lie almost the entire generative organs. This layer of fibers forms what is known as the inner muscle sheath. The sheath is well developed in some species, particuarly in the larger species of fish Proteocephalids, while in the weaker species and in Ophiotaenia especially it is poorly developed. In these cases the muscles are few in number and separated from each other by intervals. The muscles of the inner sheath pass through the intersegmental septa. Other muscle fibers which pass through the tissues of the proglottid from dorsal to ventral and from 24 ILLINOIS BIOLOGICAL MONOGRAPHS [24 the lateral edges are frequently encountered but are not as numerous as are the fibers of the muscle sheath; they do not occur in groups but usually singly. In the region of the septa the transverse and dorso- ventral fibers are more numerous and form a sort of muscular plate. The muscles of the head are not arranged in the same order as in the Cyclophyllidea, as La Rue (1909) pointed out. In transverse sections of the head the muscles are usually encountered as follows: Near the tip is a rhomboid of muscles, deeper down a transverse muscle cross and then a diagonal muscle cross, the last two forming a muscle star. The muscle star occurs in the region of the suckers but in certain cases (Riggenbach 1896) it may extend below the level of the suckers. Usually as soon as the suckers have been passed the muscles take on an arrange- ment typical of the muscle arrangement in the neck and the young pro- glottids. In longitudinal sections certain heavy muscle fibers are seen to pass from the neck to the surface of the head near the tip, others (the greater number) pass in bundles to the lower and inner surfaces of the suckers. A vertical muscle cross connecting the two adjacent suckers by the lower margin of each sucker to the upper margin of the other is also distinguishable. The muscles of the head have not been studied in many of the species. The writer has studied them in Ophiotaenia fila- roides, Proteocephalus amhloplitis, and P. singularis and to a certain extent in P. pinguis. The muscles of the head of P. singularis are de- scribed in another part of this work (vide infra) mth drawings illus- trating the structures found. /Riggenbach (1896) has studied the muscu- lature of the head of P. fossatus and Coralloiothrium lobosum. In the latter he noted certain variations from the type found in other Proteo- cephalids. These variations* are associated with the type of head found in that genus. The genital pore is situated on the lateral margin of the proglottid, right or left. Its position alternates irregularly from one side to the other. For each species the genital pore has a fairly constant location on the margin. In some species it is near the middle, and in other cases it is posterior to the middle, in others anterior. A genital papilla or eminence on which the pore is situated is not usually present. In one species, Ophiotaenia grandis, there is frequently a marked pitting or contraction about the genital pore which causes the latter to be deeply set back from the straight line of the margin. The genital pore leads into the genital atrium into which typically both cirrus and vagina open and to which the outer end of the cirrus-pouch is attached. The atrium is to be considered as an invagination of the outer body wall of the proglottid. 25] PROTEOCEPHALIDAE — LA RUE 25 The cirrus-pouch, cirrus, ductus ejaculatorius, vas deferens, vasa efferentia, and testes comprise the male reproductive system. The cirrus-pouch is a more or less cylindrical or ovoidal muscular bag which contains the cirrus and ductus ejaculatorius. At its outer end it is attached to the wall of the genital atrium by means of some of its muscle fibers. At the other end strong muscle fibers attach it to the inner dorsal surface of the muscle sheath. Some muscles are also con- tinued into the cirrus itself. The form and size of the cirrus-pouch is reasonably constant for each species if proglottids of the same degree of development be considered. Hence the length of cirrus-pouch relative to the breadth of the proglottid is useful as a diagnostic character. In some instances the cirrus-pouch is somewhat constricted about the mid- dle. This condition seems to be correlated with the act of protrusion, as the writer points out under a later caption. The greatest diameter is usually found at the inner end of the pouch. The more or less muscular cirrus, a tube the two ends of which vary somewhat in structure, passes through the length of the cirrus-pouch. The outer portion of the tube is called the cirrus while the inner and less muscular end is called the ductus ejaculatorius. Each part is char- acterized by certain structures tho the one grades over into the other almost imperceptibly. The cirrus possesses both circular and longitudi- nal muscles. The circular muscles are most heavily developed near the base or outer end of the cirrus while they are greatly reduced in the end where it passes over into the ductus ejaculatorius. Longitudinal muscles are weakly developed. At the outer end strands of muscle pass out from the cirrus to the wall of the cirrus-pouch. There are very few if any gland cells on its exterior. Its internal surface is lined by a continuation of the cuticula of the atrium. Toward the inner end of the cirrus the cuticula gradually disappears until at the inner end it is difficult to dis- tinguish. The muscles also become weaker and the outer diameter of the tube may consequently diminish in size tho in some species this region may be inflated. "With the change in the musculature and the thinning of the cuticular lining prostate gland cells appear. These char- acters mark the ductus ejaculatorius, namely, the thin wall, weak mus- cles, little or no cuticula, and the presence of the prostate gland cells. This region may be swollen into a voluminous tube for the retention of spermatozoa and hence with the coils of vas deferens may serve as a vesicula seminalis. There is no specialized vesicula. The cirrus itself is usually quite straight and is only rarely thrown into coils. The ductus ejaculatorius is frequently straight tho in a large proportion of the spe- cies it is bent or coiled in one to several coils. 26 ILLINOIS BIOLOGICAL MONOGRAPHS [26 Since the outer end of the cirrus tube is fastened to the mouth of the cirrus-pouch the cirrus is everted when protrusion takes place. The protruded cirrus is then of double thickness, being made up of the heavier walled outer tube and the thin walled inner tube. In certain species of Ophiotaenia, viz., 0. marenzelleri and 0. trimeresuri, one to three or more coils of ductus ejaculatorius are forced out into the swollen base of the cirrus. This could only occur in species in which the ductus has a considerable length. Species having a short straight ductus would not show this character. In the cases above cited the cirrus-pouch is not evag- inated as Scjiwarz (1908) stated was true of 0. marenzelleri. This con- dition of the cirrus and ductus is more fully discussed under the descrip- tions of 0. marenzelleri and 0. trimeresuri. (See also Figs. 106, 108, 199.) Such a pushing out of coils of ductus into the cirrus is not known among the species of Proteocephalus, Choanotaenia, Crepidobothrium, or Monticellia. The writer has recently seen it in some proglottids of a species of Ophiotaenia from a king snake from Florida. In certain species, notably P. fallax (Fig. 57) a set of strong circu- lar muscles and a constricted area may be fou^d about the middle of the cirrus-pouch. The inner end of the pouch may also be swollen. The presence of these muscles together with the constricted area which is not usually seen and the swollen inner end suggest a possible explanation of the process of cirrus protrusion. In all species the circular muscles of the sheath or pouch are fairly well developed while the longitudinal muscle fibers have a weaker development. A contraction of the circular muscles and perhaps also of longitudinal muscles would produce a rela- tively high pressure upon the contents of the cirrus-pouch. The inner end of the pouch is closed, 'the outer end is opened broadly and at the edges of this broad opening the cirrus walls are attached. It is evident therefore that the only escape for the contents which are under pressure is by means of this open end of the pouch through which the cirrus is everted. As an aid in the beginning of the act of protrusion, relaxation of the muscles of the cirrus and a contraction of the weak muscles which connect the cirrus to the cirrus-pouch may play a part. This action once initiated the hydraulic pressure put upon the contents of the cirrus- pouch by the contraction of the muscles of the pouch would complete the act of eversion. In certain cases where the cirrus and the ductus ejaculatorius form a straight tube through the cirrus-pouch it seems probable that a shortening of the pouch is also necessary. Such a short- ening has not actually been observed. The retraction of the cirrus is not so easily explained. It seems that strong contractions of the longitudinal muscle fibers within the walls of the cirrus and ductus ejaculatorius would be of great assistance in 27] PROTEOCEPHALIDAE — LA RUE 27 retraction. In many species the muscle fibers connecting the cirrus with the walls of the cirrus-pouch seem entirely too weak to assist much in this process. Since the inner end of the cirrus-pouch is attached to the body wall by strong muscles their contraction would lengthen the cirrus- pouch and this would exert a direct traction upon the ductus ejaculato- rius. Such a lengthening of the pouch would tend toward the produc- tion of a negative pressure which might draw the cirrus back into the pouch. In some species large numbers of cirri have been seen protruded, in others none or almost none. Protruded and unprotruded cirri have been noted among both mature and ripe proglottids. These facts stimu- late one to inquire whether the cirri are normally retracted after pro- trusion? Is protrusion of the cirrus a common occurrence in the act of copulation or is it an accident? Had those unprotruded cirri in the ripe proglottids ever been protruded? These are questions that cannot be answered from the available data nor has the author seen anything in the literature on these points. An opportunity is suggested here for experimental work. /^iggenbach (1896) considered that the broad cavity of the cirrus might be called a vesicula seminalis and that this cavity functioned as such an organ. While it is true that the cavity of the cirrus and ductus ejaculatorius might function as a vesicula, they are not structurally a vesicula. When the sexual organs become fully mature the semen is stored until ejaculated in the coils of the vas deferens which become greatly swollen. Thus the coils of vas deferens function as a vesicula seminalis altho they are not. differentiated into such an organ. JProperly speaking there is no vesicula seminalis in the Proteocephalidae. The vasa efferentia and vas deferens have been carefully described by Rig- genbach (1896) and La Rue (1909). Altho they have been observed in a number of species of the family they have not been especially re- described in the descriptions of the species because they are essentially the same in all species of the group. Their general relations may be seen in figures 90 and 180. The vasa efferentia are thin walled small tubes leading out from the covering of the testes. These tubules anastomose with some of their neighbors and finally the larger vessels unite with the inner end of the vas deferens. The vasa efferentia can sometimes be studied from toto preparations of proglottids if the testes were discharg- ing semen at the time of killing the cestode. Carefully made frontal sections stained with haematoxylin sometimes show them very well. The vas deferens is a thin walled tube of larger diameter than the vasa effer- entia. It begins near the middle of the proglottid on the inner dorsal surface of the muscle sheath. Then it makes a few or numerous coils which extend to the inner end of the cirrus-pouch which it enters. From 28 ILLINOIS BIOLOGICAL MONOGRAPHS [28 this point the vas deferens is continuous with the ductus ejaculatorius and the cirrus. Testes are numerous small ovoidal or spheroidal bodies which lie toward the dorsal surface of the medullary parenchyma within the lon- gitudinal muscle sheath. They occupy as a rule nearly the entire space between the lateral vitellaria anterior to the ovary. They leave a small free area in the region of the coils of the vas deferens. In the genus Proteocephalus the testes form one or two layers which extend from one vitelline field to the other. In one species, P. torulosus, they extend past the ovary to the posterior margin of the proglottid. In the genus Coral- lobothrium the testes form a single broad field anterior to the ovary. In Ophiotaenia, Crepidobothrium, and Acanthotaenia they form two lateral fields, one on either side of a free median zone. In rare cases some scat- tered testes may be found in this median zone. In these genera, which have been but little studied by the section method, the testes seem to form a single layer in depth. The number of testes varies widely from about 25 in some to about 400, the upper limit for other species. For each species there seems to be a characteristic number which is not constant but varies within certain limits. This range is usually not great, being 5-10-15 for cestodes with the smaller number of testes and very much greater for those cestodes which have very numerous testes. Crepido- hothrium gerrardii has from about 200 to 400 testes, the range being about 200. In mature proglottids the testes are most plainly seen. As the uteri develop and the eggs fill the uterine pouches the testes are pushed aside by the swollen uteri or they shrink and are lost to view between the walls of the uterine pouches. The organs which comprise the female reproductive system are vitellaria, vitelline ducts, vagina in all its parts, ovary, oocapt, oviduct, ootype, shell glands, receptaculum seminis, uterine passage and uterus. The vitelline follicles are small spheroidal bodies which are arranged in two long bands which extend the full length of the proglottid near the lateral margin of the latter. The follicles usually are rather compactly grouped about the central conducting tubule. Rarely the vitellaria ex- tend past the posterior edge of the ovarian lobes, and in only one known case, (Proteocephalus perplexus), do they follow along the posterior margin of the proglottid (Figs. 54, 55). The vitellaria are inside the longitudinal muscle sheath and very near the lateral nerve trunks. The central conducting tubules near the posterior end of the proglottid are known as the paired vitelline ducts which lead to the middle of the pro- glottid where they unite to form the common or unpaired vitelline duct. This may dilate to form a vitelline receptacle. From the vitelline recep- tacle the unpaired duct passes backward to join the oviduct just before 29] PROTEOCEPHALIDAE — LA RUE 29 the latter enters the ootype. The course of these duets as described by von Linstow (1891) and Kraemer (1892) was incorrect, ^^iggenbach (1896) and Bendict (1900) established their true course. The vitelline ducts, paired and unpaired, are made up of thin tissue possessing no glandular elements. The vagina is a tube of varying dimensions and character leading from the genital atrium to the middle of the proglottid and thence pos- teriad to the interovarial space where it unites with the oviduct to form the fertilization canal, which is a part of the oviduct. The vagina and cirrus-pouch alike open into the genital atrium. The initial part of the vagina may lie anterior or posterior to the cirrus-pouch and the opening of the vagina may have either of these positions, but in some species examinedj^pecially for this point the opening was dorsal to the cirrus- pouch, yin Proteocephalus the vagina is usually anterior to the cirrus- pouch altho there are a few species in which it is regularly posterior. In species of Ophiotaenia it is as frequently posterior as anterior to the cirrus-pouch, but in 0. filaroides alone it has never been observed in the posterior position. In Acanthotaenia and Crepidobothrium the vagina may be either anterior or posterior. The vagina on account of its vary- ing structure may be subdivided into four parts. These are (1) the initial part reaching from the genital atrium nearly to the middle of the proglottid, (2) the tube extending back to the interovarial space where its structure changes to (3) the receptaculum, and then (4) the lower vagina extending from the receptaculum seminis to the oviduct. These parts are distinguished by position and by structure. The initial part has an opening into the genital atrium. It is lined usually by a cuticula which in some species may be traced almost back to the receptaculum. The initial part is frequently somewhat broadened out and is somewhat muscular. Near the opening to the atrium the muscles are usually de- veloped into a sphincter muscle, the sphincter vaginae. This may have a strong development (Figs. 106, 183) or may be very weak (Figs. 47, 50, 57). The modifications of the sphincter serve as distinguishing char- acters. Noticeable on the initial part of the vagina particularly but also occurring on almost the entire length of the vagina are numerous gland cells. The longitudinal tube of the vagina presents some different appear- ances from the initial part. It is usually a straight or wavy thin walled tube of large or small diameter depending on the species and the stage of development of the proglottid. In some species as the proglottid becomes mature or especially after coitus this part of the tube is much dilated. In all species the musculature of this part of the tube is very weak or lacking entirely. Here also the cuticula of the initial part of 30 ILLINOIS BIOLOGICAL MONOGRAPHS [30 the vagina may disappear or is very thin and diflSeult to determine. In Proteocephalus macrocephalus and a few other species the vagina is ciliated throughout almost its entire length. Just after the long tube of the vagina enters the interovarial space or in some species just anterior to the mid-piece of the ovary the vagina broadens out slightly and this is followed by a sudden diminution in diameter and a change in the histological structure of the tube. This broadened part is known as the receptaculum seminis, the presence of which Riggenbach (1896) denied. Since it is somewhat different histologically and also since it serves the function of a receptaculum it may well be called a receptaculum. The writer has already presented his views on this matter in his description of the organ in Ophiotaenia filaroides (La Rue 1909). Since that time he has observed the structure in several other species and sees no reason for changing his view. From the receptaculum seminis to its junction with the oviduct the vagina may be spoken of as the lower vagina. This part is characterized by its small diameter, thick muscular walls and rich investment of gland cells. It is not ciliated in any part of its course in any species studied by the writer. The lower vagina frequently de- scribe a long loop or several coils within the interovarial space. '''^The ovary as in other TetraphyUideans is situated in the posterior end of the proglottid, is bilobed and the lobes are connected by a mid- piece. The lobes are thin, alate or club-shaped, branched or made up of several slender blind pouches, or the branches may anastomose. Rarely or never is the lobe a solid mass but it seems to be made up of more or less anastomosing branches or tubes. The whole ovary is closely in- vested with a thin membrane. The organs of the interovarial region are taken up as nearly as possible in the order of occurrence, beginning with the oocapt. The general relations of these structures are shown in draw- ings which have been reproduced (Figs. 99, 104). The oocapt is a funnel- shaped muscular organ attached to the mid-piece of the ovary and pres- ent in all the species examined. It is made up of circular and longitudi- nal muscle fibers and is surrounded by scattered gland cells. In action it is a gulping organ which by its rhythmic contractions forces the ova down the oviduct. The oviduct is a thick-walled tube made up of epi- thelial cells and around these are circular and longitudinal muscle fibers. Some gland cells are scattered along its entire length and it is lined with numerous long cilia. In its course from the oocapt it describes one or more loops or coils and then it receives the lower vagina which here pours the sperms upon the ova. The oviduct from this point on should be known as a fertilization pass^|)». This passage, which is relatively short, discharges into the ootype. However, just before entering into the ootype the oviduct receives the unpaired vitelline duct which pours out 31] PROTEOCEPHALIDAE — LA RUE 31 the product of the vitelline glands. The ootype is a slightly elongated muscular organ of small size. Its muscles are much heavier than those of the oviduct and they represent, perhaps, a higher development of the oviductal muscles. About the ootype is found a large number of long slender cells which in the aggregate have been called the shell-gland. Each cell evidently discharges by its own minute duct which may be traced well down between the muscles of the ootype. In the ootype the egg is formed. The ootype discharges directly into a duct called the uterine passage. This duct leads forward directly or after a few coils have been described and discharges the formed eggs into the median stem of the uterus at a point which is usually anterior to the posterior end of the uterus and on the dorsal side of the latter. In structure the uterine passage differs from the oviduct in the lack of strong musculature. Some- times it is difficult to find any musculature at all. There are scattered gland cells and numerous nuclei of cells which are of an epithelial nature or which belong to cells of parenchymatous origin. These structures of the interovarial space have been worked out by Monticelli (1891), von Linstow (1891), who made numerous errors; by Kraemer (1892), who likewise made some errors. Riggenbach (1896) did very careful work and so also did Benedict (1900), altho the latter erred in denying the existence of a uterine passage for his species. More recently the writer (La Rjle 1909) has worked out all these points in considerable detail. j/n all the species of the family the uterus develops as a median longitudinal tube (Fig. 105) lying in the medullary parenchyma just within the longitudinal muscle sheath and toward the ventral side of the proglottid, while the testes occupy the field toward the dorsal side of the proglottid. This long tube extends almost from the anterior end to the mid-piece of the ovary. The stem of the uterus is first seen as a rod of deeply staining cells which seem to arise from differentiating parenchyma cells in young proglottids. The rod after a considerable multiplication of cells becomes hollow throughout its entire length. By the method of outpocketing described by La Rue (1909) the uterus sends out a few or numerous branches to the right and left. These branches begin as rods of cells which rapidly multiply. Then a cavity opens through the length of the rod somewhat as the lumen appears in smaller blood ves- sels, during the development of higher animals. The rod continues to increase in length and the lumen to extend as the rod lengthens. A few of the outpocketings are directed ventrally and these eventually pierce the ventral body wall (Fig. 89) and thus provide opportunity for the discharge of eggs. The lateral pouches are formed prior to the dis- charge of eggs into the uterus and in all cases observed the pouches in- creased in size so rapidly that there was no crowding of eggs until the 32 ILLINOIS BIOLOGICAL MONOGRAPHS [32 uterus had almost attained its complete development. Those workers who ascribe the production of these pouches to the crowding of the eggs have evidently failed to read the evidence to be seen in the developing uterus. Likewise those who ascribe the splitting of the proglottid down the ventral side to the pressure of contained eggs have failed to note the fact that the ventral pouches perforate the ventral side in one or more places before the pressure of eggs is great enough to split the proglottid. The number of pouches on either side varies greatly but is reason- ably constant for each species. Proteocephalus longicollis with its three pouches (Fig. 167) on either side has the smallest number, while some of the Ophiotaeniae (Fig, 101) have as many as thirty or more. When filled with eggs the pouches in many species fill almost the entire ventral field of the proglottid, while in some species of Ophiotaenia they appar- ently take up but little more than half the width of the proglottid. The pouches come to lie very close together, so that only small septa separate them. Testes are pushed laterally or nearly obliterated by the pressure of filled pouches. The vitellaria likewise are nearly obliterated in many species while the ovarian lobes usually shrink considerably at this time. The splitting of the ventral surface and the discharge of the eggs occurs soon after. The wall of the uterus in its early stage of development appears to be made of an epithelium the cell boundaries of which are indistinct or invisible, altho the nuclei are very prominent and are closely packed together. In the later stages of the uterus the nuclei are farther separated, the outlines of the cells cannot be seen at all even tho the membrane in which the nuclei lie is thick and apparently tough. Riggenbach (1896:92) says, ''Eine dicke Membran bildet die Wand des ganzen Fruchtbehalters. Nach aussen lagern derselben stets viele kleine Zellen auf, die zwar kein eigentliches Epithel bilden, wie es bei andern Cestoden oft der Fall ist, jedoch als Reste eines solchen anzusehen sind. ' ' In this view Riggenbach may be correct. The eggs usually have three membranes altho in a few species the eggs have been recorded as having two membranes. In these cases it is possible that a third membrane was overlooked. The outer membrane of eggs that have been discharged into water is usually much larger than the others. It is thin, hyaline and spheroidal in form. Eggs preserved in utero and later examined do not show this membrane at all prominently and in some cases it might easily be considered as a part of the second membrane. The outermost membrane is smooth in out- line. The only known exception is found in the eggs of Ophiotaenia nattereri which Schwarz (1908) described as having peculiar branched booklets about its periphery. His drawing of this egg is reproduced (Fig. 194). The middle membrane is usually thick and granular and 33] PROTEOCEPHALIDAE — LA RUE 33 but little larger than the embryo. The third or inner membrane is a delicate but tough and clear membrane which is not always easy to demonstrate. It is closely applied to the embryo and might readily be overlooked. CHARACTERS OP DIAGNOSTIC VALUE Benedict (1900:339) in his discussion of these forms called at- tention to the small dependence that can be placed upon external meas- urements when used alone as a means of determining species. While in the main he is correct in his contentions it is certainly a fact that such measurements when used in conjunction with other data may be of great v^e and these should always form a part of the species descrip- tion.[/These measurements should include the dimensions of the head and suckers, the length of the strobila and its breadth at intervals or the breadth of proglottids at certain stages of development. The dimen- sions of proglottids are always of service, and of less importance are the dimensions of the neck. Data as regards the host, the locality and the habitat of the host are always of value. The older investigators made much of these data and justly so for they were unable to make a study of the internal anatomy of cestodes. At the present time such data do not seem to be as highly valued as they should. The anatomy and finer structure of the internal organs furnish the most valuable characters for diagnostic purposes. The relations of the external genitalia, of the male and female reproductive organs to each other, the number and size and distribution of the testes, character of the coils of the vas deferens, size and character of the cirrus-pouch, cirrus, ductus ejaculatorius, and the protruded cirrus are all of value for diagnosis. So also are the relations of the various parts of the vagina, the vitellaria, ovary, oviducts and all of the small oi^gaiis-of the tfrterovarial space. Of especial value are data in regard to the pouches of the uterus and the measurements of the egg membranes and the embryo. The presence of muscular elements and cilia may at times be used as distinguishing features. Drawings showing the essentials of external and internal anatomy should always form a part of a report on these animals. 34 ILLINOIS BIOLOGICAL MONOGRAPHS [34 KEY TO THE BETTER KNOWN GENERA AND SPECIES OF PROTEOCEPHALIDAE 1(70) Proteocephalids with heads which have no folds or lappets of tissue about the suckers 2 2(47) Testes lie in a single broad field between vitellaria; para- sitic in freshwater fish. Genus Proteocephalus Weinland 1858 3 3(24) Functional fifth sucker lacking, i. e. absent or vestigial 4 4(15) Testes number 100 or more _ „ 5 5( 8) Cirrus-pouch extends j^-J^ across breadth of proglottid „ 6 6( 7) Uterine pouches 4 to 8 on either side; ductus ejaculatorius nearly straight Proteocephalus agonis (Barbieri 1909) 7( 6) Many uterine pouches on either side; ductus ejaculatorius forming several coils. Proteocephalus fossatus (Riggenbach 1896) 8( 5) Cirrus-pouch extends less than ys across the breadth of the proglottid __ „ 9 9(12) Genital pore situated at middle of lateral margin of proglot- tid „.. „ „.._ 10 10(11) Uterine pouches 3 to 4 on either side; testes in 2 layers; cir- rus-pouch extending %-% across the breadth of the proglottid ; suckers 0.18-0.2 mm. in diameter. Proteocephalus torulosus (Batsch 1786) 11(10) Uterine pouches 7.to 14 on either side; testes in 1 layer, cir- rus-pouch extending Ye-yi across the breadth of the proglottid; suckers 0.095-0.16 mm. in diameter. Proteocephalus macrocephalus (Creplin 1825) 12 ( 9) Genital pore anterior to middle of lateral margin of pro- glottid 13 13(14) Uterine pouches 20 to 25 on either side; vagina anterior to cirrus-pouch; 135-155 testes. Proteocephalus perplexus La Rue 1911 14(13) Uterine pouches 10 to 12 on either side; vagina posterior to cirrus-pouch; about 200 testes. Proteocephalus sulcatus (Klaptocz 1906) 15 ( 4) Testes number less than 100 _ 16 16(17) Suckers with pointed apex and shallow cavity. Proteocephalus singularis La Rue 1911 17(16) Suckers round or oval with smooth contour 18 35] PROTEOCEPHALIDAE — LA RUE 35 18(19) Vaginal sphincter very long and strong; eestode large, robust Proteocephalus amhloplitis (Leidy 1887) 19(18) Vaginal sphincter short and weak; cestodes small „ 20 20(23) Testes in 2 partial or complete layers „ „ 21 21(22) Cirrus-pouch extends ^-34 across the breadth of the pro- glottid ; ductus ejaculatorius forms several coils ; 75-90 testes Proteocephalus filicollis (Rudolphi 1802) 22(21) Cirrus-pouch extends about yi across the breadth of the proglottid; ductus ejaculatorius nearly straight; 44-52 testes Proteocephalus esocis (Schneider 1905) 23(20) Testes in one layer Proteocephalus neglectus La Rue 1911 24 ( 3) Functional (well developed) fifth sucker present 25 25(26) Suckers pointed at posterior margin. Proteocephalus cy clops (von Linstow 1877) sp. inq. 26(25) Suckers not pointed at posterior margin 27 27(42) Testes number about 70 or less._._ 28 28(35) Cirrus-pouch extends less than % across breadth of pro- glottid 29 29(32) Embryos 0.03 mm. in diameter or greater 30 30(31) Uterine pouches 6 to 8 on either side; 30-35 testes situated in 1 layer Proteocephalus fallax La Rue 1911 31(30) Uterine pouches 7 to 14 on either side; 55-60 testes situated in 2 partial layers Proteocephalus dubius La Rue 1911 32(29) Embryos much less than 0.03 mm. in diameter. 33 33(34) Uterine pouches 9 to 14 on either side ; 35-40 testes; cestodes very small _ Proteocephalus exiguus La Rue 1911 34(33) Uterine pouches 4 to 9 on either side; 50-60 testes; cestodes of medium size Proteocephalus percae (Miiller 1780) 35(28) Cirrus-pouch extends less than % across breadth of pro- glottid 36 36(39) Testes in 1 layer _ 37 37(38) Cirrus-pouch extends Yz-Ya across the breadth of the pro- glottid; 10-14 uterine pouches on either side; embryos measure 0.016-0.018 mm. in diameter; cestodes slender. Proteocephalus pinguis La Rue 1911 38(37) Cirrus-pouch extends Va-V7 across the breadth of the pro- glottid ; 6-12 uterine pouches on either side ; embryos measure 0.0212-0.018 mm. in diameter; cestodes short and robust Proteocephalus cernuae (Gmelin 1790) 39(36) Testes in 2 layers „ _ 40 40(41) Uterine pouches 10 to 16 on either side; cestodes very small and weak Proteocephalus pusillus Ward 1910 36 ILLINOIS BIOLOGICAL MONOGRAPHS [36 41(40) Uterine pouches 3 (or 4) on either side; cestodes large and robust I*roteocephalus longicollis (Zeder 1800) 42(27) Testes number more than 70 „ „.. 43 43(44) Fifth sucker armed with minute hooks or spines. Proteocephalus osculatus (Goeze 1782) 44(43) Fifth sucker unarmed 45 45(46) Vagina anterior to cirrus-pouch; genital pore posterior to middle of proglottid; suckers 0.25 mm. in diameter. Proteocephalus skorikowi (von Linstow 1904) 46(45) Vagina posterior to cirrus-pouch ; genital pore about middle of proglottid ; suckers 0.5 mm. in diameter. Proteocephalus pentastoma (Klaptocz 1906) 47 ( 2) Testes lie in two lateral fields between viteUaria; parasitic in amphibians, aquatic snakes and lizards __ _.. 48 48(49) Cuticula of head or of head and parts of strobila covered with minute spines. Genus Acanthotaenia von Linstow 1903 49(48) Cuticula of neck free from spines or hooks 50 50(69) Suckers rounded or oval in outline. Genus Ophiotaenia La Rue 1911 51(52) Vagina always anterior to cirrus-pouch. Ophiotaenia filaroides La Rue 1909 52(51) Vagina either anterior or posterior to the cirrus-pouch..„ 53 53(62) Genital pore anterior to the middle of margin of proglottid... 54 54(57) Uterine pouches 20 or less than 20 on either side_ 55 55(56) Head 0.24-0.25 mm. broad; suckers 0.12-0.15 mm. in diame- ter; testes number 80-100; cirrus-pouch extends about Yi across the breadth of proglottid. Ophiotaenia nattereri (Parona 1901) 56(55) Head 0.54 mm. broad; suckers 0.27-0.3 mm. in diameter; testes number 100-120; cirrus-pouch extends about ^ across the breadth of proglottid. Ophiotaenia racemosa (Rudolphi 1819) 57(54) More than 20 uterine pouches on either side 58 58(61) Testes number about 100-150 59 59(60) Testes number 100-108, situated in two narrow lateral fields not near vitellaria ; several coils of ductus ejaculatorius in base of protruded cirrus. Ophiotaenia trimeresuri (Parona 1898) 60(61) Testes number 90-160, situated in two broad lateral fields extending close to vitellaria, no coils of ductus ejacula- torius in base of protruded cirrus. Ophiotaenia Ibnnhergii (Fuhrmann 1895) 37] PROTEOCEPHALIDAE — LA RUE 37 61(58) Testes number 150-215 Ophiotaenia perspicua La Rue 1911 62(53) Genital pore at or near middle of margin of proglottid 63 63(66) Heads 1.5 mm. or more in breadth 64 64(65) Muscular wall of suckers of nearly constant thickness about entire circumference; testes number 150-240. Ophiotaenia marenzelleri (Barrois 1898) 65(64) Muscular wall of suckers much thickened on anterior mar- gin ; testes number about 200. Ophiotaenia punica (Cholodkovski 1908) 66(63) Heads less than 1.5 mm. broad 67 67(68) Testes number 130-160; ductus ejaculatorius forms several coils; 24-35 uterine pouches on either side. Ophiotaenia calmettei (Barrois 1898). 68(67) Testes number 200-250 ; ductus ejaculatorius nearly straight ; 40-60 uterine pouches on either side. Ophiotaenia grandis La Rue 1911 69(50) Suckers with point of lower margin re-entrant into cavity of sucker Genus Crepidohothrium Monticelli 1899. The only know species of this genus is Crepidohothrium gerrardii (Baird 1860). 70(1) Heads with folds or lappets of tissue about suckers _ 71 71(72) A single fold of tissue partially covering the base of suck- ers; head conical Genus Choanoscolex La Rue 1911. The only known species is Choanoscolex ahscisa (Riggenbach 1896). 72(71) Many folds or lappets of tissue about suckers; anterior surface of head flattened; suckers set in flattened end of head Genus Corallohothrium Fritsch 1886. DESCRIPTION OF SPECIES In this section are described the species of the following genera: Proteocephalus, sensu strictu, Choanoscolex La Rue 1911, and Ophio- taenia La Rue 1911, of the family Proteocephalidae. The species of Monticellia La Rue 1911, belonging in the new family Monticellidae, have also been described. Other species which have been mistakenly placed in the genus Proteocephalus have been considered and where possible their rightful position pointed out. The species of Corallohothrium and of Acanthotaenia have not been re-described. 38 ILLINOIS BIOLOGICAL MONOGRAPHS [38 PROTEOCEPHALUS FILICOLLIS (Rudolphi) [Figs. 15, 58-60] 1782: Taenia from Gasterosteus 1786 : Taenia from Gasterosteus 1790: Taenia gasterostei 1800: Alyselminthus gasterostei 1802: Taenia filicollis 1803 : Halysis gasterostei 1810 : Taenia filicollis 1819 : Taenia filicollis 1844 : Taenia filicollis 1845 : Taenia filicollis 1845: Taenia ambigua 1850 : Taenia filicollis 1850 : Taenia ambigua 1858 : Proteocephalus ambigua 1858 : Proteocephalus filicollis 1872: Taenia ambigua 1889 : Taenia filicollis 1902 : Taenia filicollis 1905 : Ichthyotaenia filicollis 1909: Ichthyotaenia ambigua 1911 : Proteocephalus filicollis Specific Diagnosis: Charactt Jjength as much as 35 mm. or more. Breadth 0.8 mm. Proglottids few, 15-25. Segmentation indistinct. Proglottids attached by their full width. First proglottids broader than long, 0.20 mm. broad by 0.075- 0.080 mm. long. Mature proglottids about 0.18 mm. long by 0.370 mm. broad. Ripe proglottids 0.48-0.66 mm. long by 0.425 mm. broad. Head small, 0.090-0.120 mm. broad or perhaps a little more, not always well set off from neck. Suckers 0.042-0.055 mm. in diameter. No fifth sucker present. Neck to first traces of segmentation about 1.0 mm. long. Genital organs as in genus. Genital sinus marginal, irregularly alternating, situated near middle of segment on a papilla-form promi- nence. Cirrus-pouch about 0.130 mm. long by 0.032-0.040 mm. broad, reaching about y^-% across the breadth of the proglottid. Cirrus-canal much coiled in cirrus-pouch. Vas deferens forming mass of eccentric coils. Testes in two layers, about 75-90 in all. Vagina anterior to cirrus-pouch. Sphincter vaginae weakly developed. Receptaculum seminis present. ViteUaria made up of quite compact follicular masses, in lateral fields. Ovary bilobed, connected by an arched mid-piece. 0. F. Miiller 1782 :28-29 Batsch 1786 :241-242 Gmelin 1790 :3079 Zeder 1800 :255 Rudolphi 1802a :114-115 Zeder 1803 :334 Rudolphi 1810:106 Rudolphi 1819 :148 Bellingham 1844:317 Dujardin 1845 :583 Dujardin 1845:583 Diesing 1850:512 Diesing 1850:512 Weinland 1858 :53 "Weinland 1858 :53 Grimm 1872 :243-246 Lonnberg 1889 :15 Schneider 1902:84,86-87 Schneider 1905 :21-24 Liihe 1909 :33 La Rue 1911 :473, 474, 475 of the genus. Verv small cestodes. 39] PROTEOCEPHALIDAE — LA RUE 39 Lobes spheroidal, thick. Uterus when fully developed possessing 5-7-8 lateral pouches on either side. Eggs provided with three membranes. Outermost membrane 0.050-0.075 mm. in diameter, embryonal covering 0.032 mm., embryo 0.027 mm. Habitat : In intestine of host. Host Locality Collector Authority Gasterosteus aculeatus* Miiller Muller (1782:28-29) « « Greifswald Rudolphi Rudolphi (1802a: 1 14- 1 15) « i< Berlin Olfers Diesing (1850:512) « « Paris Dujardin Dujardin (1845:583) a (1 Ireland Bellinghain Bellingham (1844:317) n der Seite betrachtet, erscheint etwas ange- schwoUen ; wenn man es von der Flache betrachtet, so sieht man an den in Wein- geist conservirten Exemplaren eine Furche, die uber den Kopf, an dessen freiem Ende, von der einen flachen Seite des Wurms zur andern verlauft. Diese Furche ist aber gewiss keine constante Bildung, wird iber dadurch hervorgerufen, dass 43] PROTEOCEPHALIDAE — LA RUE 43 der Wurm, uberhaupt sehr contractu, sein Kopfchen ofters einzieht, namentlich wenn er in Weingeist gelegt wird. Einen Riissel besitzt er nicht. Die Saugnapfe, die eine runde Form haben, sind paarweise auf den den flachen Seiten des Kor- pers entsprechenden Kopftheilen angeordnet. Die Geschlechtsoffnungen liegen am Rande der Glieder, eine uber der andern. Alle Glieder, die mit dem Alter all- mahlig breiter werden, haben eine ziemlich unregelmassige Form, besonders aber ihre Rander. Die Farbe des Wurms ist rein weiss. Indem wir noch hinzusetzen, dass das letzte died an seinem hintern Rande bestiindig etwas aufgeschlitzt ist, haben wir eine moglichst vollstandige Darstellung des Aeussern des Bandwurms geliefert. "Dieser Bandwurm ist hochst zart .... — "Von dem weiblichen Geschlechtsorgan habe ich nur die Keimdruse und den Uterus aufgefunden ; die Keimdruse liegt in der Mitte des Gliedes und hatte in dem untersuchten Stadium ein spindelformiges Aussehen ; von ihr geht der Uterus aus, der aus einem Rohre mit feinen faserigen Wandungen besteht, das mehrere Schlingen bildet. Der Uterus verlauft in die Scheide, die sich zum Seitenrande des Gliedes begiebt, wo sie nach aussen mit einer ziemlich grossen Oeffnung miindet. "Neben dem weiblichen Geschlechtsporus liegt eine andere OeflFnung, die in das mannliche Geschlechtsorgan fiihrt. Das letzte besteht aus dem kolbenformigen Cirrusbeutel mit dem nach innen gewendeten Cirrus, der an seinem Ende etwas anschwillt. Hinter dem Cirrusbeutel liegt die doppelte Samendrtise. "In dem letzten, also am meisten entwickelten Gliede waren nur Keime, nicht aber entwickelte Eier zu sehen." Von Linstow (1878:231) reported as hosts for Taenia filicolUs and Taenia amhigua only those which had been reported by Diesing (1850). Zsehokke (1884:16-17) reported and briefly described a eestode from Perca fluviatilis, Lake Lucerne, which he considered to be Taenia fili- collis End. His specimens probably belonged to Proteocephalus dubius La Rue. Leidy ( 1886 :62-63 ) thought that he had found Taenia filicollis in the intestine of Amia calva from North Carolina. His specimens probably belonged to the species for which La Rue (1911) proposed the name Proteocephalus perplexus La Rue. Lonnberg (1889:15) reported the finding of Taenia filicollis in Gasterosteus pungitius at Upsala. He added a very little to Rudolphi's diagnosis. Kraemer (1892) reported and described a form from the intestine of Coregonus fera, Lake Lucerne, which he first identified as Taenia filicollis Rud. In the same paper Kraemer showed that his Taenia fili- collis and his Taenia ocellata were identical. Riggenbach (1896) and Ben- edict (1900) accepted Kraemer 's determination. This species has been shown to differ from the Taenia filicollis of Rudolphi and is described under the name Proteocephalus fallax La Rue 1911, where a full dis- cussion of the position of Kraemer 's species may be found. Benedict 44 ILLINOIS BIOLOGICAL MONOGRAPHS [44 (1900) described an American species of cestode under the name Pro- teocephalus filicollis (Rud.). In a note he changed the name to Proteo- cephalus ocellata (Rud,). He accepted Kraemer's statement that Rudolphi's Taenia ocellata and T. filicollis were identical. For this form which proves to be a new species La Rue (1911) proposed the name, Proteocephalus exiguus La Rue. Schneider (1902:21-23) reported a parasite from Perca fiuviatilis, in Finland, as Ichthyotaenia filicollis (Rud.). This form he later (1903:13 and 1905:15-17) considered to be identical with 0. F. Miiller's Taenia percae. Schneider (1902:84, 86- 87) reported a specimen from Gasterosteus pungitius as Ichthyotaenia filicollis (Rud.). In a later paper (1905:21-24) he considered this form to be Ichthyotaenia ambigua Dujardin and here he gave the first good description of this species. LUhe (1909) gave a diagnosis of this species under the name Ichthyotaenia anihigua Dujardin. His diagnosis added nothing to the data given by Dujardin (1845) and Schneider (1905). La Rue (1911:473, 474, 475) presented some of the conclusions that are given in the present paper at greater length. The name Taenia gasterostei as proposed by Gmelin (1790) for this species is not available because it was first used by Miiller (1782) to designate the species now known as Schist ocephalus solidus. For the same reason the name Alyselminthus gasterostei Zeder (1800) is ren- dered invalid. The name Taenia filicollis Rudolphi (1802) being first used to indicate this species remains available. The generic name is Proteocephalus as indicated by "Weinland (1858). It is of importance here to determine the systematic position of the specimens reported by Grimm (1872) and by Schneider (1902 and 1905). A careful compari- son of their descriptions with' Dujardin 's (1845) description of Taenia amhigua shows that they evidently belong to the latter species. One notes that Grimm's material was found in Gasterosteus aculeatus while Schneider's specimen came from G. pungitius, and a consideration of these data at once precipitates the question as to the possibility that T. amhigua Dujardin and T. filicollis Rudolphi might not prove to be identical and hence synonymous. The answer to this question must be sought in the study of the collection records and in a comparison of the structures of the forms involved. In regard to habitat one may present certain general considera- tions that should have weight. The identity of the two forms can not be considered proven because they have been found together in a single host or separately in different members of a host species, for numerous instances could be cited in which a species or an individual of that species served as host for two or more closely related species of cestode. Nevertheless, it is true that a knowledge of the host is considered to 45] PROTEOCEPHALIDAE — LA RUB 45 have an important bearing on the proof of an identity. Frequently the knowledge that two forms have the same species for a host furnishes the first intimation that they may prove to be identical. One may also make the statement that the finding of specimens apparently belonging to the same species in two or more unre- lated host species may give an early intimation that these specimens i>elong to different species. While it is true that certain cestodes seem to be limited in their habitat to a single host species there is a sufficiently large body of facts to warrant the belief that in general cestode species are not so limited. It is of common acceptance that closely allied hosts having a wide distribution and inhabiting the same regions and espe- cially when they have similar feeding habits very frequently harbor the same species of parasites. Gasterosteus aculeatus and G. pungitius are closely allied, have wide distribution, inhabit the same region, and have similar feeding habits. Taenia ambigua has been reported from G. aculeatus by Grimm and from G. pungitius by Dujardin and Schneider. Taenia filicollis has been reported from G. aculeatus by Rudolphi, Goeze, Diesing, Du- jardin, and Bellingham, and from G. pungitius by Diesing (from speci- mens collected by Nitsch and Creplin) and Lonnberg. So far as hosts are concerned there is evidence to believe that Taenia filicollis and Tae- nia anibigua are identical species. Against this identity is the fact that Dujardin 's description of T. filicollis indicates a larger form than does his description of T. ambigua. It is a well-known fact, however, that a considerable variation in length and breadth may exist in the same species of cestode. These discrepancies in size may be due to the degree of maturity and to the contraction states of the individual worms. It is not known whether Dujardin 's specimens of T. ambigua had at- tained their full development nor is this known concerning the speci- mens described by Grimm or Schneider. There are no statements to show whether Dujardin measured his specimens while alive or after preservation. This would make a real difference. Attention has already been called to the fact that in regard to the egg measurements made by Dujardin for the two forms in question there is pretty good agreement. There is not sufficient evidence at hand to prove positively that Taenia ambigua is identical with Taenia filicol- lis, yet it seems that the evidence for the identity is stronger than the evidence against it. Therefore in this work the writer will consider that these species are identical and since Taenia filicollis has the right of priority that name should be retained. It is to be hoped that this dis- cussion, which in no way can be considered to settle the problem of the identity of these species, will be the incitement to a genuine compara- 46 ILLINOIS BIOLOGICAL MONOGRAPHS [46 tive study of the cestodes of Gasterosteus aculeatus and G. pungitius. There is doubtless a large amount of such material already brought together in the museums and private collections of Europe upon which an investigator could work. Schneider's material was found for the most part in Gasterosteus pungitius from Obersee near Reval, Esthonia (a province in Russia) in the months of May and June. Never more than four cestodes of this species were found in a single host. He also studied a single specimen found by Dr. K. M. Levander in Gasterosteus pungitius. This speci- men was reported by Schneider (1902:84, 86-87) as Ichthyotaenia fili- collis (Rud.). For my study Dr. H. B. Ward very kindly secured one of Schneider's specimens of this species, stained in carmine and mounted in toto, from Dr. K. M. Levander in Helsingfors. It bears the label, "Ichthyotaenia ambigua, int. Gast. pungitius 23/10 VI, 04." The description which follows is based on Schneider's (1905:21-24) descrip- tion and on the writer's observations on this one mounted specimen. Schneider's longest specimen measured as much as 35 mm. long by a maximum breadth of 0.8 mm. and it possessed 17 proglottids. Of these the anterior were broader than long and they were united by their whole width. Proglottids well filled with eggs are longer than broad and have a well rounded outline. The specimen studied by the writer has about 25 proglottids. Of this number but a few at the anterior end are young. These are followed by a large number of nearly mature and mature proglottids and these in turn by a small number of ripe proglottids. The strobilation is indistinct. The first proglottids meas- ure about 0.075-0.080 mm. long by 0.200 mm. broad while the mature proglottids measure about 0.180 mm, long by 0.370 mm. broad and the ripe ones about 0.48-0.660 mm. long by 0.45 mm. broad. An end pro- glottid tapers posteriorly and is 0.975 mm. long by 0.425 mm. broad. Schneider states that the scolex is small, 0.100-0.120 mm. broad, and not well set off from the neck. The suckers measure 0.055 mm. in diam- eter. No fifth sucker is present. The neck is relatively broad and its length is about one-fourth that of the body. In the specimen examined by me the breadth of the head at the base of the suckers is 0.090 mm. It is very short and not well set off from the rather broad neck. Suck- ers are about 0.042 mm. in diameter over all. The first traces of seg- mentation occur at a point about 1.0 mm. behind the head. This makes the neck equal to about % the length of the entire body. It is stated by Schneider that the excretory vessels are quite wide ; that the two ventral vessels which communicate in each segment with the exterior through a submarginal pore measure 0.03 mm. in diameter ; and that the dorsal vessels are smaller, their diameter being 0.0075 mm. 47] PROTEOCEPHALIDAE — LA RUE A7 The genital pore is marginal, irregularly alternating, and situated about the middle of the proglottid length. It is rather prominently situated on a little eminence which is most evident in ripe proglottids. This eminence may be caused by a pushing out of that region by nearby organs. The cirrus-pouch measures about 0.130 mm. long by 0.032-0.040 mm. broad. Its length goes into the proglottid breadth from three to four times. The cirrus-canal, as Schneider states, is greatly coiled within the cirrus-pouch and it broadens out at iis proximal end to form a vesicula 0.030 mm. broad. Coils of the vas deferens form a mass which lies toward the porose side of the proglottid. The testes in the preparation examined by the writer lie in two layers of about 35-50 testes each. Thus the total number of testes is about 75-90 or more. Schneider found that the testes measure 0.055-0.062 mm. in sagittal and 0.035-0.045 mm. in frontal diameter. The vagina lies anterior to the cirrus-pouch. Schneider found a weak sphincter vaginae near the vaginal opening. It was not visible in the specimen which, the writer studied. The vagina passes in a curve to the middle of the segment and thence posteriad to the interovarial space. Schneider found a small receptaculum seminis just anterior to the ovary. The vitellaria are quite compact follicular masses in the lateral fields of the segments. Of the ovaries Schneider writes, "The ovaries appear as spherical bodies when seen from the surface. In the posterior segments, after they have fiJ.led the uterus with eggs, they wither completely or the remains of the genital organs, pressed together into a triangular area, are recognizable as two small round bodies in the posterior region of the segment. I hold that Grimm (1872, p. 246) erro- neously considered this triangular area to be the ovary when he says: 'the ovary lies in the middle of the segment and has in its observed condition a spindle-like appearance' ". The ovary is bilobed, the some- what spheroidal lobes being connected by a short arched mid-piece. In the ripe proglottids observed by me the ovary could still be distin- guished. The uterine passage was found by Schneider opening into the uterus posterior to the middle of the proglottid and opposite to the pre- formed opening of the uterus to the exterior. When immature the uterus is a median tube but when fully developed it has 5-7-8 lateral pouches on either side. As observed by Schneider the outer membrane of the egg has a diameter of 0.050-0.075 mm. The embryonal covering measures 0.032 mm. and the embrj^o itself 0.027 mm. These measurements of the egg agree pretty well with the measurements as given by Dujardin (1845). The embryos especially agree well in size, and it may be pointed out that this is of importance in seeking to prove an identity. 48 ILLINOIS BIOLOGICAL MONOGRAPHS [48 P. filicollis somewhat resembles P. agonis Barbieri but it may be differentiated from that species by its relatively shorter cirrus-pouch, by a different position of the mass of coils of vas deferens, by its larger testes which are arranged in two layers while the testes of P. agonis are in one layer. P, agonis has no genital papilla while in P. filicollis there is a simulation of one. P. filicollis is readily distinguished from P. duhius La Rue and P. fallax La Rue by its smaller size, by its lack of a fifth sucker, by its more numerous testes, shorter cirrus-pouch and smaller proglottids. The embryos of P. filicollis are smaller than those of P. fallax. P. filicollis differs from P. pusUlus Ward and P. exiguus La Rue in not having a fifth sucker, in having smaller suckers, a smaller head, more testes, and fewer uterine pouches. P. filicollis differs greatly from P. percae in the lack of a fifth sucker, in the size of body, head and suckers, in the proportions of the proglottids, in the size of the cirrus-pouch, ovaries, etc. It likewise differs from P. cernuae in prac- tically the same points as stated for P. percae. P. filicollis is smaller than P. esocis. It has a shorter cirrus-pouch and a larger number of testes. The proportions of the proglottids are different. The two spe- cies are alike in not possessing a fifth sucker. PROTEOCEPHALUS ESOCIS (Gui. Schneider) [Figs. 16, 61-63] 1905: Ichthyotaenia esocit Gui. Schneider, 1905:19-20 1911: Proteocephalus esocis La Rue, 1911:475 Specific Diagnosis: The characters of the genus. Cestodes small and slender, 1-4.7 cm, long, maximum breadth 0.7 mm. Scolex 0.140 mm. broad, 0.105 mm. thick. No fifth sucker, nor vestige of it. Suckers shallow, weak, small, about 0.050 mm. in diameter, directed anteriad. Diameter of sucker opening 0.026-0.032 mm. Neck 2-5 mm. long. Sixty- six proglottids in specimen 4.7 cm. long, youngest proglottids twice as broad as long, 0.370 mm. broad by 0.170 mm. long. Middle proglottids broader than long, 0.680 mm. broad by 0.390 mm. long. Last proglottid longest, 0.650 mm. long by 0.460 mm. broad at anterior end. Segmen- tation not evident. Transverse intersegmental furrows shallow. Sur- face smooth. Genital organs as in genus. Genital pore not on genital papilla. Pore marginal, irregularly alternating, about middle of proglottid. Cirrus sheath relatively long, extending nearly to middle of proglottid. Length of cirrus-pouch 0.230-0.250 mm. Cirrus sinuous. Vas deferens, a mass of coils in middle of proglottid. Testes, 30-38 visible in mature 49] PROTEOCEPHALIDAE — LA RUE 49 proglottids, 44-52 in young proglottids. Testes arranged in two par- tial layers between vitellaria. Diameter of testes, 0.050-0.090 mm. Va- gina anterior to cirrus-pouch. Near vaginal opening a small sphincter vaginae. Receptaculum seminis anterior to ovary. Passages in inter- ovarial space as in genus. Ovary bilobed, lobes ovoidal, vitellaria sparse, follicles small. Uterus not observed. Two pairs of excretory vessels, ventral and dorsal. Dorsal vessels small, ventral vessels much larger. Habitat: In intestine of Esox lucius L. (type host) ; Reval, Es- thonia (type locality). This species was described and delineated by Gjii. Schneider ( 1905 : 19-20). La Rue (1911:475) included it in a list of species belonging to the genus Proteocephalus. This species from Esox lucius taken at Reval in Esthonia, a prov- ince of Russia, Apr. 30, 1904, is briefly described by Gui. Schneider (1905). Thanks to Dr. H. B. Ward the writer has had some of Schnei- der's preparations and alcoholics for examination. The paucity of alcoholic specimens prevented the use of the section method. The writer has therefore been compelled to be content with a study of toto preparations and specimens cleared in glycerine. The description fol- lowing is based largely on Schneider's data tho wherever possible the writer has introduced his own findings. The worms are small and slender 1-4.7 cm. long. A maximum breadth of about 0.7 mm. was observed. No worms had ripe proglot- tids. The diameter of the scolex is about 0.140 mm. The four shallow suckers directed partly forward are weak, small, and about 0.05 mm. in diameter. A vestigial fifth sucker is lacking, tho perhaps a slight thickening of cells in the anterior part of the head is to be considered as the vestige of the shrunken sucker (Schneider). My measurements of a head and its suckers are : breadth 0.140 mm., thickness 0.105 mm., diameter of suckers 0.053 mm., diameter of sucker openings 0.026-0.032 mm. A most careful search of Schneider's toto preparation and of the specimen cleared in glycerine failed to reveal a trace of a fifth sucker or vestige of it. The last might not have been visible under these con- ditions. A functional fifth sucker certainly is not present. The suckers are quite prominent, the sucker cavities shallow. The slightly de- pressed head possesses a short flattened tip. The head is not well set off from the neck. Schneider says that the length of the neck is about y3 the length of the body. The writer finds it to be from 2.5-3-4.5 mm. Schneider's largest specimen, 4.7 cm. long, was made up of 66 proglottids. The youngest proglottids were about twice as broad as long, the middle ones somewhat broader than long, and the posterior 50 ILLINOIS BIOLOGICAL MONOGRAPHS [SO ones quadrate or a little longer than broad. The intersegmental fur- rows were not plain. The measurements of the proglottids in a glycer- ine specimen examined by the writer were as follows: First proglot- tids 0.370 mm. broad by 0.170 mm. long, middle and mature proglottids 0.680 ram. broad by 0.390 mm. long. The last proglottid in the strobila was the longest, measuring 0.650 mm. long by 0.460 mm. broad at ante- rior end. The segmentation is not e\^dent. The proglottids are joined by their full breadth and the transverse furrows between the segments are very shallow. No longitudinal furrows are present. Drawings of three regions (Figs. 61, 62, 63) show the proportions of the segments at anterior, post-middle, and posterior region. The genital pore, not marked by a papilla, is marginal, irregularly alternating in the strobila, and is situated about the middle of the pro- glottid. The cirrus-sheath is relatively very long and slender, for it extends about to the middle of the proglottid. Its length in the broad- est proglottids is about 0.230-0.250 mm. Schneider reports that its inner end lies very near the dorsal muscle layers. This is also the case in P. percae, P. pitiguis La Rue, P. exiguus La Rue and a number of other Proteocephalus species. The cirrus runs through the cirrus-pouch in a sinuous course ^^^thout the formation of a vesicula seminalis. The vas deferens forms a fairly large mass of coils in the middle of the segment. This mass however is much smaller than in P. fallax La Rue or in P. exiguus La Rue. Schneider found about 30 testes in each seg- ment, lying in a single layer, about 8 in a transverse row, and they measured 0.080-0.090 mm. in sagittal by 0.040-0.050 mm. in frontal diameter. It has been found difficult to count the testes in the more mature proglottids. Thirty-eight testes are shown in nearly mature proglottids (Fig. 62) while in the younger proglottids where they are smaller and more easily distinguished the writer counted 44-48-52. The testes seemed to be in two partial layers filling the area between the vitellaria. The larger testes measure as much as 0.070-0.080 mm. tho the larger number measure about 0.050 mm. Schneider found the diameter of the two ventral excretory- vessels to be about 0.015 mm. and that of the two dorsal about 0.0025 mm. The vagina (Fig. 62) opens anterior to the cirrus-pouch. Very near the opening, 0.030 mm. from it, is a sphincter muscle 0.015 mm. thick, according to Schneider. The wTiter was unable to observe this. From its opening the vagina as a broad tube describes a long smooth curve to the middle of the proglottid, then it bends posteriad and passes back to the interovarial space. As the vagina nears the middle of the segment the lumen becomes constricted. Early in its course it crosses the cirrus-pouch diagonally. The vagina is dorsal to the uterus. 51] PROTEOCEPHALIDAE — LA RUE 51 Schneider found a small receptaculum seminis just anterior to the ovary. According to Schneider the passages in the interovarial space bear the relations customary to Proteocephalids. The ovary is bilobed, the lobes being like two elongated balls connected by a slender arched mid-piece. The vitellaria are lateral, follicular, sparse, and the indi- vidual follicles are small. The uterus was not observed by Schneider. It is not well developed in any of the specimens examined by the writer. Schneider saw the opening of the uterine passage and the pre- formed uterus opening just a little posterior to the middle of the pro- glottid. No eggs were seen. No proglottids were ripe. This species is quite closely allied to the P. filicollis (Rud)^ (amhiguus) described by Gui. Schneider (1905). However it is differ- entiated from P. filicollis by its much longer cirrus-pouch and by its larger testes. P. filicollis (Schneider's specimen) shows a slight genital prominence upon which the genital pore is situated. It differs very markedly from the P. pinguis La Rue found in our North American Esox lucius. The P. pinguis is a larger worm with a larger head, larger suckers, a functional fifth sucker, a relatively shorter cirrus-pouch, and a larger number of testes. P. fallax La Rue, P. exiguus La Rue, P. pusillus Ward, and P. percae (0. F. Miiller) are readily distinguished from P. esocis by means of the fifth sucker and many other character- istics which are best shown in the comparative tables. P. macrocephalus (Creplin), a form without a fifth sucker, is much larger, has more numerous testes, a relatively shorter cirrus-pouch and in other ways also it differs widely from P. esocis (Schneider). PROTEOCEPHALUS AGONIS (Barbieri) [Figs. 158, 174, 185] 1909: Ichthyotaenia agonis Barbieri, 1909:334-341 1911: Proteocephalus agonis La Rue, 1911:475 Specific Diagnosis: Characters of the genus. Cestodes of small size. Strobila 3-4 cm. long, maximum breadth of same about 0.5 mm. Scolex small, 0.168 mm. in diameter, unarmed. No fifth sucker. Suck- ers circular, symmetrically arranged on head, size? Neck quite long, as much as 3 mm., breadth 0.140 mm. Neck not well differentiated from strobila. Proglottids very variable in form and number. At times as many as 50-70. First proglottids broader than long. Mature proglottids longer than broad, 0.580-0.620 mm. long by 0.330-0.370 mm. broad. Ripe proglottids filled with eggs, nearly quadrate, length and breadth about 0.5 mm. 52 ILLINOIS BIOLOGICAL MONOGRAPHS [52 Genital aperture marginal, irregularly alternating, situated near middle of proglottid length. Male organs as in genus. Testes spher- ical, 0.031-0.038 mm. in diameter, about 100 in number. Testes packed in area between vitellaria. Coils of vas deferens in middle of proglot- tid. Ductus ejaculatorius nearly straight. Cirrus straight, with a thick wall. Cirrus-pouch ovoidal, broad at inner end, extending to middle of proglottid. Female organs as in genus. Vagina always an- terior to cirrus-pouch. Uterus in ripe proglottids made up of 4-6-8 lateral pouches on either side. Diameter of eggs 0,037-0.038 mm. Habitat: In intestine and pyloric coeca of Alosa finta var. lacus- tris Fa, (type host) ; Lake Como, Italy (type locality). The material was collected by Prof. Ciro Barbieri at Bellagio on Lake Como in Italy from the intestines and pyloric coeca of Alosa fiiita var. lacustris Fa. He found them here in great numbers, up to 1200- 1400 in a single host. Barbieri (1909) described this species. La Rue (1909:475) in- cluded it in a list of species of Proteocephalus. Since it was impossible to secure specimens for study the present description is based upon Bar- bieri 's description. The scolex (Fig. 158) is very small, with a diameter of about 0.168 mm. It is unarmed and has no fifth sucker. The four suckers are circular in outline and they are symmetrically arranged on the head. The neck, which is about 3 mm. long and 0.140 mm. broad, is not well differentiated from the strobila. The proglottids are very variable in number and form. One well developed individual with ripe eggs in the last proglottid had 50-70 proglottids. The first proglottids are broader than long. Mature proglottids are longer than broad, 0.580- 0.620 mm. long by 0.330-0.370 mm. broad. Ripe proglottids filled with eggs are nearly quadrate, length and breadth being about 0.5 mm. The length of the worm is variable. Well developed individuals measure 30 mm. long while a single individual measured 40 mm. The genital aperture is marginal, irregularly alternating, situated about the middle of the length of the proglottid, and marked by a shallow depression. The testes (Fig. 185) fill the whole area between the vitellaria anterior to the ovary. They are nearly spherical, 0.031- 0.038 mm. in diameter. Barbieri figures about 100 testes. The coils of the vas deferens form a thick mass which occupies the middle region of the proglottid. Its walls are thin and its lumen large. The ductus ejaculatorius has a sinuous course in the inner two-thirds of the cirrus- pouch but apparently it forms no closely twisted coils before it passes over into the straight heavy-walled cirrus. The cirrus-pouch extends 53] PROTEOCEPHALIDAE — LA RUE S3 to the middle of the proglottid. It is ovoidal with its broadest part at the inner end. Its wall is thick, thickest at the outer end. The ovary is bilobed, the lobes being oval in shape with smooth outlines. The vitellaria are lateral, longitudinal, follicular glands which lie just inside of the lateral ducts. Oviduct, ootype, and other organs of the interovarial space are as in other species of the genus. The vagina (Fig. 185) always lies anterior to the cirrus-pouch. It widens slightly and again narrows in its course to the middle of the proglottid. Near the inner end of the cirrus-pouch it bends posteriad and thence takes a direct course to the interovarial space where it forms several coils. The uterus (Fig. 174) containing eggs is made up of 4-6-8 lateral pouches which in fully ripened segments fill up the space between the vitellaria. The excretory system is of the usual type. Two pairs of lateral excretory ducts take their origin in the head region. They empty into a small bladder situated at the base of the last proglottid. No second- ary openings were observed in the head but they were found in the posterior region of each proglottid. The eggs have a diameter of 0.037-0.038 mm. Barbieri failed to state whether this measurement included only the embryo or embryo with its membranes. Larval stages were found in Bythrotrephes and Leptodora. This species, as will be seen from its position in the tables at the end of this section, is most closely related to P. esocis (Schneider). It is differentiated from that species by its different proportions, by its much smaller and more numerous testes, by the position of the coils of the vas deferens and by the relation of the vagina to the cirrus-pouch. P. agonis while resembling P. filicollis in size differs from that species in having a longer cirrus-pouch, in the excentric position of the coils of vas deferens, and in having smaller and more numerous testes which lie in one layer. P. agonis is readily distinguished from P. fallax, P. duhius, P. pusUlus, and P. exiguus by its lack of a fifth sucker, by its more numerous and smaller testes, and by its less numerous uterine pouches. 54 ILLINOIS BIOLOGICAL MONOGRAPHS [54 1900: 1911; PROTEOCEPHALUS EXIGUUS La Rue [Figs. 14, 50-52, 118, 135-138] Proteocephalus filicolUs Benedict, 1900:355-365 Proteocephalus exiguus La Rue, 1911 :477-478 Specific Diagnosis: Characters of genus. Strobila short and slender. Length 9-15-25-38 mm. Maximum breadth 0.425-0.646-0.8 mm. Segmentation not evident. Intersegmental furrows shallow. Neck 2-4-7-10 (?) mm. long by 0.10-0.20 mm. broad. First proglottids longer than broad or nearly quadrate. Mature and ripe proglottids longer than broad. Ripe proglottids considerably larger than mature ones, 0.680-1.190 mm. long by 0.460-0.595 mm. broad. End-proglottid elongated, pointed posteriorly, 0.714-1.50 mm. long by 0.40-0.646 mm. broad. Head somewhat globular, flattened dorsoventrally, bearing four suckers on its broadest part. Breadth of head 0.120-0.160-0.170 mm. Suckers 0.058 mm. broad by 0.069-0.085 mm. long. Opening of suckers about 0.040 mm. in diameter. Fifth sucker muscular, functional, 0.037- 0.048 mm. in diameter. Common genital sinus alternating irregularly, situated near middle of lateral margin of proglottid. Testes 35-54 in number, in one layer, between vitellaria, anterior to ovary. Diameter of testes 0.04-0.05 mm. Vas deferens forming mass of coils in mid-field. Cirrus-pouch 0.289-0.340 mm. long, reaching to the middle of segment. Cirrus straight, 0.10 mm. long when protruded. Vagina anterior to cirrus-pouch, crossing cirrus-pouch near middle. Sphincter vaginae weak, 0.008 mm. thick. Lobes of ovary retort-shaped with smooth out- lines. Vitelline follicles small, not compact. Uterus when fully devel- oped with 9-14 lateral pouches on either side. Embryos about 0.019- 0.021 mm. in diameter, second egg membrane 0.036-0.046 mm., outer membrane 0.038-0.06 mm. Habitat: In stomach (probably by post-mortem wandering) and intestine of host. Host Locality Collector H. B. Ward H. B. Ward H. B. Ward Authority Coregonus nigripinnis C. prognathus C. artedi Lake Michigan near Charlevoix As above As above La Rue La Rue La Rue Type : Alcoholics No. Ch. 7c, Ch. 2c, and an unnumbered bottle in Doctor H. B, Ward's collection, from Coregonus nigripinnis, C. progna- ihus, and C. artedi. Type locality, Lake Michigan, near Charlevoix. 55] PROTEOCEPHALIDAE — LA RUE 55 Benedict (1900:355-365) described some cestodes which had been collected by Dr. H. B. Ward while engaged in a biological investigation of Lake Michigan under the auspices of the Michigan Fish Commission during the summer of 1894. The hosts were Coregonus nigripinnis, C. prognathus, and C. artedi. Benedict who had for comparison some specimens identified by Zschokke as Taenia ocellata Rud. (probably P. fallax La Rue) thought his material and Zschokke 's specifically iden- tical. He, however, called attention to the fact that Zschokke 's speci- mens had been nearly dried out in transit and consequently were almost ruined for study. Accepting Kraemer's statement that Taenia filicollis Rud. and T. ocellata Rud. were identical he used the name Proteocepha- lus filicollis (Rud.) to designate his form. Later he discovered that the name Taenia ocellata Rud. had page precedence in the original paper by Rudolphi (1803) and in a foot-note he called attention to the fact that the name Proteocephalus ocellata (Rud.), mis-spelling for ocella- tus, should be used to designate the form. La Rue (1911:477-478) distinguished this species from P. filicollis and described it as a new species P. exiguus. Careful examination of prepared specimens from some of the same lots used by Benedict in his research and a study of one of his slides together with a comparison of these with specimens which Zschokke had sent to Dr. H. B. Ward under the name of Taenia ocellata — (now No. 09.9 in Professor Ward's collection) — has convinced the writer that Bene- dict's species is a new one. La Rue (1911) proposed for it the name Proteocephalus exiguus La Rue by reason of the small size of the indi- viduals. Benedict worked out the morphology of the form quite cor- rectly and probably would have given due weight to the difference be- tween his own and Zschokke 's specimens had the latter been in good condition. This species is based upon the work of Benedict (1900:355-365) and upon a further examination of, and collection of, data from certain lots of alcoholic material in Dr. H. B. Ward's collection from which Benedict secured his specimens for study. These bottles bear the labels "Long-jaw, stomach. Charlevoix Jy. 16, '94". "Ch. 7 c, Cestodes, Etc. Stomach Black-fin Charlevoix, Jy. 16, '94." "Ch. 3 c, cestodes. Core- gonus Artedi Jy. 12, '94". Slides have been prepared from the first two lots. The specimens which were examined carefully by the writer ranged in length from 9-10-15 mm. Benedict found the length to vary from 12-16-25 and one specimen only attained the length of 38 mm. This one case seemed to have been due to an extreme attenuation for the neck was 7 mm. long. This attenuation may have been caused by the method 56 ILLINOIS BIOLOGICAL MONOGRAPHS [56 of killing. The maximum breadth found by the writer varied from 0.425-0.595-0.646 mm. while Benedict records a maximum of 0.8 mm. The globular head according to Benedict is 0.120 mm. broad. The writer found it to be 0.148-0.160-0.170 mm. broad. The suckers placed just above the broadest zone are directed slightly anteriad. They are 0.069-0.085 mm. long by 0.058 mm. broad with an opening of 0.042-0.048 mm. by 0.027-0.032 mm. Benedict states that the sucker is 0.040 mm. in diameter, but it seems that he must mean the diameter of the opening and not the diameter over the whole sucker. A fifth sucker is present, 0.037-0.048 mm. in diameter. This from toto preparations is appar- ently a true sucker. Benedict says it has the **same structure and musculature that the four large suckers possess." His drawing of the head is reproduced (Fig. 138). The neck measures 2-4 mm. in length by 0.110-0.120 mm. broad. Benedict found the neck to be 5-10 mm. long by 0.10-0.20 mm. broad. The neck passes over into the first proglottids almost imperceptibly. The first proglottids are longer than broad or nearly quadrate. These very immature proglottids are few in number. The anlage of the genital organs appear very early and in proglottids a little further back mature sexual organs appear. Mature proglottids are longer than broad and are few in number. Ripe proglottids are longer than broad. Three of these measured 0.935 by 0.595 mm., 0.680 by 0.560 mm., 1.190 by 0.460 mm. Ripe proglottids are considerably larger than the mature. The increase in length, breadth and thickness is rapid. The longest proglottid in the strobila is usually the last one and sometimes also it is the broadest. Three terminal proglottids measured 1.190 by 0.646 mm., 0.714 by 0.51 mm., 1.50 by 0.40 mm., the length being stated first. The end proglottid is variable in form and functional. It usually tapers to a blunt point at its posterior end where the excretory pore is situated. The segmentation is not evident. The angles at the ends of the proglottids are scarcely marked and the intersegmental furrows are shallow. The total number of proglottids in a strobila is small, 10-12- 14-15-20. Benedict found one specimen with 40 segments. Benedict's findings on points of histology are probably correct and have not been checked over. The common genital sinus is situated near the middle of the margin of the proglottid, usually slightly ante- rior thereto. It alternates irregularly. The testes (Fig. 50) are 37-50-54 in number, 35-50 according to Benedict. They measure 0.040-0.045-0.050 mm. in diameter. The testes lie in a single layer between the vitellaria and anterior to the ovarj'. In toto mounts the writer could not make out with certainty the coils of the vas deferens yet they seemed to lie in the middle of the 57] PROTEOCEPHALIDAE — LA RUE 57 proglottid near the dorsal wall. Benedict figures the vas deferens as forming a coil extending beyond the middle of the segment. The cirrus-pouch (Figs. 50, 51, 52) is elongated, slightly broader near its inner extremity and slightly constricted near the middle. It reaches the middle of the segment or even beyond that point in mature pro- glottids. Its length increases with the maturity of the segment. The following measurements of its length were taken from successive pro- glottids, 0.289, 0.296, 0.313, 0.330, 0.341 mm. the last being the maxi- mum length found. The unprotruded cirrus is straight. The writer has not seen it evaginated. According to Benedict the evaginated cirrus extends 0.10 mm. from the male opening. The ductus ejaculatorius iii straight. The vagina (Figs. 50, 51, 52) opens into the common genital sinus and it always lies anterior to the cirrus-pouch. In a single proglottid the vagina was found posterior to the cirrus-pouch. This is probably to be considered as an abnormality or a very rare variation. A weak sphincter vaginae occurs a short distance from the vaginal opening. This sphincter is 0.008 mm. thick and is circular in cross section (Bene- dict). As Benedict has described it, the vagina extends straight in for a short distance then it "bends backward and inward passing under the middle of the cirrus-sac". The ovary very much resembles that of P.fallax (Kraemer's Taenia ocellata) in shape. The lobes are thick and solid. Benedict's comparison of their shape to that of a retort is excel- lent. The ovary is early decadent. The relations of the organs of the interovarial space are typical of the genus as Benedict has described them. The vitellaria are follicular. The follicles are not large nor are they closely packed. They too are decadent early. The uterus (Figs. 51, 52) in ripe proglottids consists of a median tube and 9-14 lateral pouches on either side. These pouches occupy the ventral part of the segment while the testes are dorsal. *'The eggs which are found in the uterus have a diameter of 0.02 mm." (Benedict). Measurements by the writer gave a range of 0.019-0.021 mm. for the embryo and 0.036-0.046 mm. for the second membrane. The outer membrane meas- ures 0.038-0.060 mm. The second membrane is thick and granular while the outer membrane in uterine eggs is thick and hyaline. This species somewhat resembles P. piisillus Ward but is differenti- ated from that species by the smaller size of its head, by its very much smaller suckers and smaller sucker openings. This species has a much longer neck than has P. pusillus. The character of the segmentation of the two worms is utterly different being very evident in P. pusillus^ with deep constrictions between proglottids. In P. exiguus segmenta- tion is not evident. The number of proglottids in P. pusillus is greater 58 ILLINOIS BIOLOGICAL MONOGRAPHS [58 than in P. exiguus. The mass of coils of the vas deferens in P. pusillus is much smaller than in P. exiguus and it lies almost wholly anterior to the cirrus-pouch while in P. exiguus it lies more nearly at the end of the cirrus-pouch. The testes are more numerous in P. pusillus and the cirrus-pouch is much shorter than in P. exiguus. The lobes of the ovaries in P. pusillus are bent strongly posteriad while such a condition is never so marked in P. exiguus. The proportions of the proglottids are greatly different. P. exiguus closely resembles P. fallax La Rue. It differs from that species in having a smaller head, smaller suckers, a smaller fifth sucker, a shorter neck, fewer and smaller proglottids, more testes, a shorter cirrus when evaginated, and a greater number of lateral uterine out- pocketings. The embryos of P. exiguus are smaller than in P. fallax. The differences are of such a character and of such a constancy as to be of specific importance. This species resembles P. a^gonis Barbieri even more than it does P. fallax except that P. agonis has no well de- veloped fifth sucker. In total length and in the size of the proglottids P. exiguus is the larger. P. exiguus has more uterine pouches and fewer but larger testes than has P. agonis. Unfortunately Barbieri 's description fails in some particulars, nevertheless sufficient data are given to establish the difference between the two species. P. exiguus resembles P. duhius La Rue but its head, its suckers, its proglottids, and its cirrus-pouch are smaller. These two species have about the same number of testes. The embryo of P. dubius is much larger than that of P. exiguus. P. exiguus differs radically from P. ambiguus and P. esocis in the possession of a fifth sucker. Other points of difference are also to be found. P. exiguus is smaller than other North American species of Proteocephaliis. PROTEOCEPHALUS PUSILLUS Ward [Figs. 2-4, 53-55] 1910 : Proteocephalus pusillus Ward, 1910 :1185-1187 1911: Proteocephalus pusillus La Rue, 1911:475 Specific Diagnosis: Characters of the genus. Cestodes small, length 30-50 mm. Maximum breadth 0.350 mm. Proglottids few. Seg- mentation distinct. Head spheroidal, frequently much contracted, breadth about 0.300 mm., length about 0.260 mm. Four suckers placed at broadest zone of head. Suckers deep, 0.140 mm. long by 0.110 mm. broad. Fifth sucker well developed, muscular, 0.060 mm. in diameter. Neck 1.0-1.5 mm. long by 0.21 mm. broad. First proglottids broader than long, breadth of same 0.090 mm. Mature proglottids longer than 59] PROTEOCEPHALIDAE — LA RUE » broad. Eipe proglottids much longer than broad. Length of same 0.84-1.4 mm., breadth 0.18-0.35 mm. End-proglottid present and fertile. Genital sinus marginal, irregularly alternating, situated at end of first %-% of proglottid. Vagina usually anterior and dorsal to cirrus- pouch, rarely posterior. Testes 44-60-70 in number, arranged in two layers between vitellaria. Length of same 0.06-0.096 mm., breadth 0.04-0.05 mm. Vas deferens a small mass of coils anterior to cirrus- pouch. Cirrus-pouch 0.095-0.106 mm. long by 0.053-0.060 mm. broad, reaching 5^-14 across the proglottid breadth. Ductus ejaculatorius forming one or two coils in cirrus-pouch. Cirrus short and straight. Vagina never crossing cirrus-pouch. Sphincter vaginae and receptacu- lum seminis not seen. Ovary bilobed, posterior. Lobes short, thick, free ends of same frequently pressed posteriad and together. Vitellaria sparse, follicles small. Uterus with 10-14-16 lateral pouches on either side. Eggs not observed. Habitat: Intestine and esophagus of Salmo sehago Girard (type host), Sebago Lake, Me. (type locality) ; intestine and pyloric coeca of Cristivomer namaycush Walbaum ( ?), Lake Temagami, Ontario. Type: Material in bottles 15, 16, 42, in Professor "Ward's collec- tion from Sebago Lake, Me., summer of 1907, and slides from this material. "Ward (1910:1185-1187) first described this species which he had found in the Sebago salmon. "Ward's description follows. "Proteocephalus pusUlus nov. spec. — Adult cestode with short strobila, meas- uring only 30 to 50 mm. in length, Proglottids scanty, segmentation distinct. Head much contracted. Neck i to 1.5 mm. long by 0.21 mm. broad. First pro- glottids 0.09 mm. broad changing gradually until in mature proglottids the length greatly exceeds the breadth. Ripe proglottids measure 0.84 to 1.4 mm. long by 0.18 to 0.35 mm. broad. Terminal proglottids present and fertile. Sexual organs typical for Proteocephalus ; uterus median, with 10 to 14 lateral outpocketings on either side. Testes numerous, within vitellaria. Genital pore lateral, one-third to two-fifths of length of proglottid from anterior margin of same. Ovaries bilobed, median isthmus indistinct, anteroposterior diameter nearly equal to breadth of both lobes. Only a few specimens obtained from a single host species, Salmo sehago. "This species approaches most nearly to P. ocellata and P. percae among known species. Unlike the new species, however, both of these older forms have a fifth sucker, a few lateral uterine outpocketings, a longer neck, differently shaped ovaries, and markedly different proglottids. "In specimens with developed proglottids the head was so much contracted or distorted that any special description would be of little value. One could easily observe the general features characteristic of the genus. There was no well developed terminal or fifth sucker, and the end organ, which is known to €0 ILLINOIS BIOLOGICAL MONOGRAPHS [60 replace it in many forms of this genus, was inconspicuously developed, if present. Personally, 1 incline to the view that on more careful examination this structure will be found in all species, even those in which its absence has been made a matter of record. Accordingly, not much weight can be put in its presence or absence in any individual. "Three plerocercoid larvae or young cestodes were found in company with Proteocephalus pusillus, which I regard as young forms of this species. The largest came from the salmon which was most heavily infected with this cestode parasite. It was 3.15 mm. long and had begun to assume clearly the appearance of an immature cestode. The head measured 0.3 mm. wide by 0.26 mm. long, and the suckers 0.14 mm. in length by o.ii mm. in width. The neck was slightly nar- rower than the head, but was not clearly set off from the body, which was very imiform in diameter and measured 0.25 mm. in average width. The posterior end of the body was swollen into a rounded knob about 0.35 mm. broad and of ap- proximately the same length. This feature was evidently produced by a powerful contraction of the terminal region of the body. In and near it one could see very indistinct indications of proglottid formation. In form, size, and general aspect this young cestode was in full agreement with the anterior regions of the mature cestodes of this species with which it was associated. The head, which was not contracted, showed on careful study the delicate outline of a rudimentary end organ. While such a structure was not demonstrated in the mature individuals described above, one can say positively that if present it could not have been seen owing to the greatly contracted condition of the adult scolices. I believe that its presence will be demonstrated in more favorable specimens. The complete agree- ment of this largest larva with the mature specimens in all other features compels me to regard both as different stages in the development of the same species. "The other larvae were still in early stages of development and probably had been ingested by the salmon at a very recent date. Their relationship is not so clear in all respects, and yet I do not hesitate to associate with the new species of Proteocephalus a plerocercoid or young cestode obtained from the same host as the adult worms and the older larva just described. The head is broadly conical, without furrows, and measures 0.3 mm. in breadth. The suckers measure 60 to 74 fjL. in diameter. There is no rostellum or fifth sucker to be found, while the end organ is so poorly developed as to be visible with difficulty and only under the most favorable circumstances. The neck is nearly as broad as the head. In gen- eral appearance this larva resembles the adult cestode and the older larva pre- viously described. With some reserve one may also assign to this species a single plerocercus taken from another specimen of Sabno sebago. The head, which meas- ures only 150 ^ in breadth, is shaped like that of the young cestode and like it is without rostellum or fifth sucker, while the end organ is difficult to demonstrate. Neither furrows nor ridges are seen on the larva, which has a total length of 1.14 mm. The sucker measures only 30 to 45 fi in diameter. The neck is slightly nar- rower than the head. This form certainly belongs to the genus Proteocephalus and probably to the species already described." 61] PROTEOCEPHALIDAE — LA RUE 61 La Rue (1911:475) listed this form among other Proteocephalus species. Dr. H. B. Ward has very kindly loaned the writer his speci- mens for study. More preparations have been made and from them the writer has been able to secure additional data on this species. The type material in bottles 15, 16 and 42 was taken from the intestine and oesophagus of Salmo sehago Girard, Sebago Lake, Me. Jy. 27 and Aug. 6, 1907. Other specimens which the writer has assigned to this same species were taken by Dr. H. B. Ward from two specimens of Cristivomer namaycush Walbaum (?), Lake Temagami, Ontario, in August, 1911. These last are described separately. This is one of the smaller species of Proteocephalus. The observed length is from 30-50 mm. for specimens which have ripe proglottids. Proglottids are few in number and the segmentation is distinct. The head is spheroidal but in many cases it is so greatly contracted that its structure can not be determined. The head measures 0.300 mm. broad by about 0.260 mm. long. The four suckers measure about 0.140 mm. long by 0.110 mm. broad. The sucker cavity is quite deep. At the apex of the head (Figs. 2, 3, 4) is a fairly well developed fifth sucker which in well stained specimens shows an evident musculature and a cavity. Ward (1910) reported only an end organ or vestigial fifth sucker instead of a fifth sucker. When his specimen was restained and mounted it showed a well formed fifth sucker. Characteristic fifth suckers measure about 0.060 mm. in diameter. The neck is 1-1.5 mm. long by about 0.21 mm. broad. It passes over quickly into the first pro- glottids which are broader than long. Their breadth is about 0.090 mm. The proglottids rapidly become quadrate or even longer than broad. Ripe proglottids measure 0.84-1.4 mm. long by 0.18-0.35 mm. broad. An end-proglottid is usually present and fertile. The common genital sinus is marginal, situated at the end of the 1/ first %-% of the proglottid. Its position alternates irregularly. The testes (Figs. 54, 55) number 44-60-70. Since these lie in two layers the figure does not show all of them. In less mature proglottids where the testes are much smaller and more distinct they can be counted more readily. The testes measure 0.06-0.072-0.096 mm. long by 0.040- 0.050 mm. broad. The vas deferens (Figs, 53, 54, 55) forms a small mass of coils in the middle of the proglottid. The larger part of the mass is anterior to the cirrus-pouch, a condition not usually met with in this genus. The cirrus-pouch which is rather heavy reaches 34 -H. across the proglottid breadth. Its length is 0.095-0.106 mm. and its breadth 0.053-0,060 mm. The ductus ejaculatorius forms a coil or two within the cirrus-pouch before passing over into the short straight cir- rus which has not been seen protruded. On account of a lack of suffi- 62 ILLINOIS BIOLOGICAL MONOGRAPHS [62 cient material but very few sections have been made and these were too poor to yield much valuable data. The vagina (Figs. 54, 55) usually opens anterior and dorsal to the cirrus-pouch but rarely (Fig. 53) it is posterior to the same. The number of proglottids examined have been too few to establish whether the posterior position of the vagina is normal. Even when in the ante- rior situation the vagina does not cross the cirrus-pouch. From its opening it makes a long curve toward the middle of the proglottid which it reaches at a point posterior to the inner end of the cirrus- pouch. The vagina is dorsal to the uterus. A vaginal sphincter could not be demonstrated, and if present it must be very weak. The pres- ence of a receptaculum seminis has not been demonstrated. The bilobed ovary (Figs. 53, 54, 55) is peculiar in that the lobes which are short and very thick are pressed closely together. This is a condition not yet found regularly in any other species of the genus altho Nufer (1905) found it in P. macrocephalus. In transverse sections the thickness and compactness of the ovary are noted at once. The vitellaria are sparse, the follicles small. The ducts of the interovarial space have not been thoroly investigated. An ootype and an oocapt are present. In ripe ploglottids the uterus (Fig. 53) shows 10-14-16 lateral out- pocketings on either side. No uterine pores have been seen. The eggs have not been observed. Other specimens which the writer has provisionally assigned to this species were taken by Dr. H. B. Ward from the pyloric and intestinal regions of Cristivomer namaycush Walbaum (?), Lake Temagami, On- tario, August, 1910. It seems that the determination of the host must remain somewhat in doubt -f or there was no attempt at the identification of the fish when it was caught and it was not preserved. The identifica- tion was made from the memory of the appearance of the fish after the return of the expedition. Both Professor Reighard and Professor Ward when questioned by the writer thought there could be little doubt of the determination. These specimens bear the lot numbers Tip, Tlj, T2h, and T2p in Dr. H. B. Ward's collection. The specimens are small, measuring up to 20-30 mm. long. No specimens have ripe proglottids. When the worm is fully mature it is perhaps considerably longer. Measurements of a number of specimens yielded the following data : Average breadth of seven heads 0.284 mm., maximum breadth of same 0.340 mm., minimum 0.244 mm.; average length of six heads 0.177 mm., maximum length of same 0.238 mm., min- imum 0.133 mm. ; average length of seventeen suckers 0.134 mm., maxi- mum length of same 0.179 mm., minimum 0.106 mm.; average breadth of thirteen suckers 0.108 mm., maximum breadth of same 0.127 mm., 63] PROTEOCEPHALIDAE — LA RUE 63 minimum 0.096 mm. ; sucker opening 0.058-0.080 mm. ; diameter of fifth sucker about 0.060 mm. Average length of six necks 1.49 mm., maxi- mum length 1.70 mm., minimum 1.02 mm.; neck narrow, up to 0.135 mm. The proglottids are few, numbering about 30-40. First proglot- tids are broader than long, or quadrate, length soon exceeds breadth, and mature proglottids are longer than broad measuring up to 0.56-0.68 mm. long by 0.24-0.265 mm. broad. The maximum breadth of 0.340 mm. was observed in a proglottid measuring 0.357 mm. long by 0.340 mm. broad. Segmentation is very distinct. The genital pore is near the middle, usually anterior thereto but sometimes posterior. The vagina lies anterior to the cirrus-pouch. There are about 44-66 testes and these measure about 0.159 by 0.180 mm. in diameter. They form two irregular layers in the region bounded by the vitellaria and ovary. In many proglottids of this lot the testes are not as fully developed as in the proglottids of specimens from Salmo sehago. This condition facilitates the counting of the testes. The coils of the vas deferens form a small mass situated for the most part anterior to the cirrus-pouch. Within the cirrus-pouch the ductus ejaculatorius forms a single coil and then it passes over into the small cirrus. The cirrus-pouch usually extends to the middle of the proglottid or nearly thereto. It has a length of about 0.111-0.150 mm. The average length of eight pouches was 0.133 mm. In breadth the cirrus-pouch measures 0.053-0.070 mm. The lobes of the ovary are thick and are bent back until they nearly meet in the median line. Vitellaria are sparse. A fully developed uterus has not been observed. Of the drawings repre- senting P. pusillus, figures 2, 4, and 55 were made from specimens which came from Cristivomer namaycush. All the other drawings of this spe- cies were made from specimens taken from Salmo sehago. In general these two forms agree very well but there are two points of minor disagreement. These are in regard to the length of the cirrus- pouch and the size of the suckers. As to the former the difference in length is but a matter of a few micra and this perhaps may be explained by the fact that the proglottids are in different states of contraction. As for the other point of difference it may be stated that in the speci- mens taken from Cristivomer namaycush the suckers are on the average about the size of the suckers of the typical P. pusillus but in one or two cases observed the length and breadth of the sucker is appreciably larger. It is to be remembered that the measurements of the suckers of the typical P. pusillus are based on a single head. Consequently the range of size of suckers in that species has not been determined. Tho no ripe proglottids were present in the material from Cristivomer no- 64 ILLINOIS BIOLOGICAL MONOGRAPHS [64 maycush and consequently some of the best diagnostic features could not be determined it seems best to consider these forms identical. Proteocephalus pusUlus Ward is closely allied to P. exiguus La Rue but is differentiated from that species by its larger head, larger suckers, and larger sucker openings. The measurements of proglottids of the two species are much alike. However, the type of segmentation is very dissimilar. In the reproductive organs P. pusillus varies from P. exi- guus in having more numerous and larger testes. The testes of P^ pjisillus lie in two layers while in P. exiguus they are in one layer. The cirrus-pouch of P. exiguus is much longer than that of P. pusillus. The ovaries of the two species are very different. In the one species the lobes are slightly arched while in the other the lobes are bent nearly together. The lateral uterine pouches of P. exiguus are larger and scarcely as numerous as in P. pusillus. P. pusillus somewhat resembles P. fallax La Rue but it is smaller. It has a larger head and suckers, more numerous and larger testes, a much shorter cirrus-pouch, and more numerous uterine outpocketings than P. fallax. The ovaries of the two species are very different. P. pusillus differs from P. agonis Barbieri in having a fifth sucker. Moreover P. pusillus is a larger form than P. agonis. P. agonis has smaller and more numerous testes than P. pusillus, and also fewer uterine outpocketings. P. pusillus differs radically in size and propor- tions from P. percae (0. F. Miiller). P. pusillus differs from P. esocis (Schneider) in having a larger head, larger suckers, in possessing a fifth sucker, and a shorter neck. The proportions of the segments are different. The length of the cirrus-pouch and the ratio of its length to the proglottid breadth differ greatly in the two species. The character of the segmentation is very unlike. There is very little probability that P. pusillus is the same as P. salvelini (Linton). P. salvelini has no fifth sucker. Its head, suckers, and cirrus-pouch are larger than those of P. pusillus. Linton's description of P. salvelini does not furnish many characters for determination and his drawing of the proglottid is so indistinct that it cannot be relied upon as a source of data. 65] PROTEOCEPHAUDAE — LA RUE 65 PROTEOCEPHALUS PINGUIS La Rue [Figs. 29-32, 35, 36, 88-93] 1911 : Proteocephalus pinguis La Rue, 1911 :478. Specific Diagnosis: Characters of genus. Strobila short and slen- der. Observed length up to 90 mm. Maximum breadth 1.24 mm. Neck 3-7 ram. long by 0.20-0.25 mm. broad. Proglottids, first in chain very short, 0.05 mm. long by 0.25 mm. broad. Mature and ripe proglottids nearly quadrate or in a few ripe proglottids length exceeding the breadth, 0.595 by 0.595 mm. up to 0.730 mm. long by 0.595 mm. broad. End-proglottid present and functional. Segmentation not very distinct. Intersegmental furrows shallow. Head conical, flattened dorso-ventrally, without furrows, presenting great variations in shape. Breadth of head about 0.33 mm., thickness 0.22 mm., length 0.20-0.25 mm. Suckers cup- shaped, deep, muscular. Diameter of suckers 0.095-0.105 mm., of aper- ture of sucker 0.06-0.07 mm. Diameter of fifth sucker 0.05-0.075 mm. Common genital sinus irregularly alternating, situate at or near middle of lateral margin of proglottid. Testes ovoidal, 0.05 mm. long by 0.04-0.05 mm. broad, 54-70 in number, in a single layer taking up field between vitellaria anterior to ovary. Ductus ejaculatorius nearly straight. Cirrus well muscled, straight, length when protruded 0.07- 0.08 mm. by 0.02-0.025 mm. broad. Cirrus-pouch short, stout, 0.13-0.14 mm. long by 0.05-0.06 mm. broad. Ratio of length of cirrus-pouch to breadth of proglottid 1 :3 or 1 :4. Vagina anterior, but vaginal opening always dorsal to cirrus-pouch. Vagina crossing inner end of cirrus- sheath. Sphincter vaginae small. Receptaculum seminis small, situate anterior to ovary. Uterus, when fully developed, with 10-14 lateral pouches on either side. Ventral uterine pores 2-3 in number. Embryos 0.016-0.018 mm. in diameter. Habitat: In intestine of host. Host Locality Sebago Lake, Collector Authority Esox reticulatus H. B. Ward La Rue Le Sueur Maine (the present paper ; Esox lucius "Walnut Lake, T. L. Hankinson La Rue Linn. Mich. (the present paper) Esox lucius Lake Geneva, A. J. Coats La Rue Linn. Wis. (the present paper) Type: Alcoholics in Dr. H. B. Ward's Sebago Lake collection Nos. 4, 6, 7, 8, 9, 107. Slides of same. The material was collected by 66 ILLINOIS BIOLOGICAL MONOGRAPHS [66 Dr. H. B. Ward from Esox reticulatus Le Sueur (type host) ; Sebago Lake, Maine (type locality). Co-type: Alcoholics No. TLH413 in Dr. H. B. Ward's collection, from Esox lucius Linn., Walnut Lake, Michigan, and slides of the same. Autotyi)e : Alcoholics No. 10.35 in collection Dr. H. B. Ward Irom Esox lucius Linn., Lake Greneva, Wisconsin. Leidy (1888:169 and 1890:417) described some specimens of ces- todes from Esox reticulatus. The two specific names which he proposed for them the writer considers to be synonyms and has included under the one name, Proteocephalus nematosomu (Leidy). Leidy 's specimens were considerably larger than the specimens of P. pinguis and appar- ently are not the same. A more complete discussion of Leidy 's species occurs later in the article. La Rue (1911:478) briefly characterized this species and proposed for it the name Proteocephalus pinguis. This study is based, for the most part, upon specimens collected by Dr. H. B. Ward from the intestines of Esox reticulatus Le Sueur at Sebago Lake, Maine, while engaged in an investigation of that lake for the U. S. Bureau of Fisheries, in the summer of 1907. Portions of the study are also based upon specimens secured by Prof. T. L. Hankinson from Esox lucius Linn, in the course of a biological investigation of Walnut Lake, Mich., during the summer of 1906. This last material was referred to in a former paper. La Rue (1909:25), as "A new spe- cies, which I shall describe in detail later ". It bears the number TLH413 in Professor Ward's collection. Dr. H. B. Ward examined six specimens of Esox reticulatus Le Sueur while at Sebago Lake. These six fish yielded sixteen entire Proteocephalids and pieces as follows: No. 4, 1 head-l-2 pieces; No. 6, 2 heads+2-3 pieces; No. 7, 1 head-|-2 pieces; No. 8, 11 headsH-2 pieces; No. 9, 1 head; No. 107, 5 heads, 1 young cestode-f-10 large pieces. In many instances the specimens re- ported as heads were complete worms while in others the end proglottid and part of the strobila were missing. Thus the infection of Sebago Lake hosts was light. Hankinson 's material in bottle No. 413 from Esox lucius of Walnut Lake was probably from a single host. It con- tained 60-70 si)ecimens of P. pinguis. A bottle, No. 10.35 in Dr. H. B. Ward's collection, bearing the label "from stomach and intestine of a 'pickerel,' Lake Geneva, Wisconsin, Jy. 1, 1904. A. J. Coats, collector", contained 5 or 6 complete specimens of P. pinguis La Rue and several pieces of the same species. Replying to a letter of inquiry Prof. (Jeoi^ Wagner of the University of Wisconsin states that only one species of pickerel, the Esox lucius, is found in Lake (Jeneva, Wisconsin. The data on this species were obtained from specimens cleared and examined in 67] PROTEOCEPHALIDAE — LA RUE 67 glycerine, from specimens stained and mounted in toto and from trans- verse and frontal sections. These cestodes are small and slender (Fig. 32). The largest speci- men from the Sebago Lake material measured 90 mm. long by 1.24 mm. in maximum breadth. The longest specimen from the Walnut Lake host measured 66 mm. long by 1.0 mm. in maximum breadth. The strobila of a 50 mm. specimen is made up of an unsegmented neck 3-7 mm. long by 0.20-0.25 mm. broad followed by 300 proglottids. The youngest proglot- tids measure about 0.050 mm. long by 0.250 mm. broad. Further along in the chain these increase in length and breadth until in mature and ripe proglottids the length and breadth are about equal. Measurements of several ripe proglottids are as follows, the length in millimeters being stated first: 0.595 by 0.595, 0.680 by 0.680, 0.595 by 0.663, 0.730 by 0.595 mm. In transection the proglottids are elliptical. A typical functional end-proglottid with a rounded posterior end is present. The segmentation is not very plain, for the inter-segmental furrows are not deep and the corners of the proglottids do not project. The lateral margins are rounded and smooth. The head (Figs. 29-32, 35, 36) is a cone-shaped structure somewhat flattened dorso-ventrally. It is not marked by folds or furrows. Its breadth is about 0.33 mm., its thickness about 0.22 mm., its length about 0.20-0.25 mm. In extreme cases the head may attain a breadth of 0.45 mm. This extreme breadth is due to a contraction of the longitudinal muscles of the head and neck. A collection of these specimens shows heads of very different states of contraction. The head bears on its broadest part four deep cup-shaped muscular suckers which are directed forward and outward. On its apex the head bears a well formed muscular fifth sucker. The diameter of the suckers ranges from 0.095-0.105 mm., while the diameter of the aperture varies from 0.06-0.07 mm. The fifth sucker measures 0.05-0.075 mm. in diameter. Altho its cavity is quite shallow it has the appearance of being functional for it possesses a typical musculature (Fig. 93). The cuticula and musculature have not been found to differ in their essential features from those of other members of the genus. The ner- vous system in the head is much like that of Ophiotaenia filaroides. A ganglionic mass is located at the level of the suckers (Fig. 93). Two main lateral nerve trunks extend throughout the length of the strobila. No accessory nerve trunks were observed. The excretory system in the head is made up of four main longi- tudinal canals which at various levels receive many anastomosing coiled vessels which pass through the tissues of the scolex and neck in every direction. In the strobila there are two pairs of lateral excretory ves- sels, ventral and dorsal respectively. These lie within the medullary 68 ILLINOIS BIOLOGICAL MONOGRAPHS [68 parenchyma. The dorsal vessel passes dorsad and the ventral vessel ventrad to the cirrus-pouch and vagina. In diameter the ventral vessel greatly exceeds the dorsal and its lining membrane is thin while the membrane lining the dorsal vessel is thick. A posterior excretory com- missure in each proglottid could not be found. Numerous secondary excretory openings which are connected with the ventral vessel and less frequently with the dorsal vessel have been seen. The drawing (Fig. 91) shows rather an extraordinary case in that the duct is larger and more extensive in its connections than is usual. In the end-proglottid the four main excretory ducts discharge to the exterior by a common pore. A bladder could not be seen. The common genital sinus is marginal, situated at or near the mid- dle of the proglottid. While the vagina lies anterior to the cirrus-pouch, the opening of the vagina, without exception, is dorsal to the opening of the cirrus (Figs. 88, 90). There is no genital papilla. The testes (Fig. 92) are numerous, 54-70. These are in a single layer in the medullary parenchyma, occupying nearly the entire field between the vitellaria anterior to the ovary. The testes measure as much as 0.05 mm. long by 0.04-0.05 mm. broad. The vasa efferentia (Fig. 90) form a network of fine anastomosing tubules just dorsal to the testes and within the medul- lary parenchyma. The main branches of the vasa efferentia unite to form the larger vas deferens. The junction occurs at a point near the^ median line about one-fourth the distance from the anterior to the pos- terior end of the segment. From this point of juncture the vas deferens forms a mass of coils extending to the cirrus-pouch. These coils function as a vesicula seminalis. When the vas deferens enters the cirrus-pouch it receives some additional -glandular elements, the prostate cells. This part of the vas deferens is called the ductus ejaculatorius. The ductus in this species is very nearly straight. The cirrus which is a continua- tion of the ductus ejaculatorius has a heavier musculature than is pres- ent in any other part of this canal. The cirrus lies in the pouch as an almost straight organ. When protruded it measures 0.07-0.08 mm. long by 0.02-0.025 mm. broad. The cirrus-pouch is elongated oval in outline. It is short and stout, being 0.13-0.14 mm. long by 0.05-0.06 mm. broad. The ratio of its length to the proglottid breadth is 1 :4 to 1 :3. The vaginal pore opens into the genital sinus just dorsal to the cirrus-pouch tho the greater part of the initial part of the vagina itself lies anterior to the pouch. A small sphincter vaginae is situated near the opening. In its course to the mid-field the vagina crosses the inner end of the cirrus-sheath. When passing posteriad to enter the inter- ovarial space the vagina is straight, not sinuous or coiled. Just anterior to the ovary the vagina dilates slightly to form a receptaculum seminis. The relations of the vagina are shown in figures 88, 90, and 92. The ovary is bi-lobed . The lobes (Fig. 92) are elongated oval and smooth in 69] PROTEOCEPHALIDAE — LA RUE 69 outline. The vitellaria are typical of the genus. The uterus is formed of a median ventral-lying tube which extends nearly the full length of the proglottid. From this tube, by the process described for Ophiotaenia filaroides, lateral outpocketings arise. These lateral pouches (Fig. 92) number 10-14 on either side. As the pouches become filled with eggs the outlines of some of them are nearly obliterated. Yet in all but the ripest proglottids the full number is visible. Sections through mature and ripening proglottids show the pouches in all stages of development. Sections also reveal the ventral diverticula which finally come to open on the surface. Such diverticula were described in an earlier paper (La Rue 1909:36) for Ophiotaenia filaroides and their presence in other spe- cies was at that time noted. In P. pinguis the number of ventral diver- ticula is greater than Gui. Schneider (1905) reported in P. macrocepha- lus, P. percae, P. esocis, and P. ambiguus but smaller than the number reported by the writer for 0. filaroides. A drawing (Fig. 89) of a frontal section just below the cuticula shows two of these openings. In such sections the openings, usually two or three, and the tubes leading up to them could be readily traced. A specimen cleared in glycerine showed these openings beautifully. The actual count of openings on 25 consecutive proglottids of this specimen is as follows : 1, 2, 3, 2, 2, 2, 1, 1, 2, 3, 2, 2, 2, 2, 2, 3, 2, 4, 3, 2, 4, 2, 3, 3, 3. The uterine eggs were observed only in preserved condition. The outer mucilaginous envelope could not be seen. The embryos measured 0.016-0.018 mm . Proteocephalus pinguis La Rue is a much larger form than P. esocis (Gui. Schneider). It has a fifth sucker which the latter lacks. It dif- fers from that species in having a larger head, larger suckers, larger proglottids, more testes and a relatively shorter cirrus-pouch. P. pin- guis differs from P. pusillus "Ward, a species occurring in the same local- ity, in the possession of a larger head, larger suckers, larger proglottids which have proportions different from those of P. pusillus. Moreover, the segmentation is of a different character and the relative lengths of the cirrus-pouches in the two worms are very different. P. pinguis dif- fers very much from P. exiguus La Rue in size, in the proportions of the proglottids, in the size of the head and of the suckers, in the relative length of the cirrus-pouch, in the character of the uterine pouches and in the size of the embryos. P. pinguis differs from P. macrocephalus (Creplin) in having a fifth sucker, in being considerably smaller, in the relative length of the cirrus-pouch, in the number of testes, and in the size of the embryos. P. pinguis is smaller than P. ambloplitis (Leidy), P. singularis La Rue and P. perplexus La Rue. There is also a difference in the size and character of the head and suckers. It is further differentiated from 70 ILLINOIS BIOLOGICAL MONOGRAPHS [70 those species by the presence of a functional fifth sucker which those species lack. P. pinguis is quite different from the European forms which have fifth suckers. These are P. percae (O. F. Miiller), P. fallax La Rue, P. duhius La Rue, P. cernuae (Gmelin), P. longicollis (Rud.). It differs from them in size of body, size of suckers and of proglottids, in the relative length of cirrus-pouch, in the size of the embryos and in the number of testes. PROTEOCEPHALUS FALLAX La Rue [Figs. 23, 56, 57, 150, 170, 178, 179] 1884 1884 1892 1892 1905 1905 1911 Taenia ocellata Zschokke 1884:13-14, in part ( ?) Taenia longicollis Zschokke 1884:14-15 Taenia filicollis Kraemer 1892:535-555 Taenia ocellata Kraemer 1892:572-576 Proteocephalus ocellata Nufer 1905 in part( ?) Proteocephalus longicollis Nufer 1905 in part( ?) Proteocephalus fallax La Rue 1911:475-477 Specific Diagnosis : Characters of the genus. Cestodes quite small. Length up to 100 mm. Maximum breadth as much as 1.20 mm. Head somewhat globose, 0.150-0.200 mm. in breadth by 0.105-0.150 mm. thick. Head well set off from neck. Suckers situated near broadest zone of head. Diameter of suckers 0.064-0.085 mm. Diameter of sucker opening about 0.040 mm. Fifth sucker present, functional, about 0.058 mm. in diameter. Neck narrow, length 2-6 mm. First proglottids quadrate or longer than broad. Mature proglottids quadrate or broader than long, 0.34-0.46 mm. broad by 0.34 mm. long. Ripe proglottids longer than broad, rarely measuring as muclj as 1.19 mm. broad by 1.36 mm. long. Segmentation indistinct, margins smooth. Genital sinus marginal, alternating, situated near middle of the proglottid. Testes 30-35 in number, irregularly scattered in single layer between vitellaria and anterior to ovary. Diameter of testes 0.037-0.060 mm. Cirrus-pouch in mature proglottids 0.196-0.255 mm. long, in ripe proglottids 0.37-0.42 mm. long. Ratio of length of cirrus-pouch to breadth of proglottid 1:3-1:2. Cirrus and ductus ejaculatorius nearly straight. Length of protruded cirrus 0.026 mm. Vas deferens forming a mass of coils in middle of proglottid. Female organs typical of genus. Vaginal opening anterior to cirrus- pouch. Vaginal sphincter weak. Ovary bilobed, lobes solid, thick, elon- gated ovoidal in form. In ripe proglottid ovary lies in triangular area between pouches of uterus. Vitellaria lateral, sparse. Uterus ventral. 71] PROTEOCEPHALIDAE — LA RUE 71 in ripe proglottids with 6-8 lateral pouches on either side. Uterine pores 2-3 in number. Outer membrane of uterine eggs thin and hyaline, mid- dle membrane granular, 0.036-0.041 mm., embryo 0.031-0.0336 mm. in diameter. Habitat: Intestine of Cor eg onus fera (type host) ; Lake Lucerne, Switzerland (type locality). Type: No. 09.9 in Professor H .B. "Ward's collection. Slides from same lot in Professor Ward's collection. Zsehokke (1884) reported and described in a very general way five species of Proteocephalus. His Taenia salmonis umhlae and Taenia torulosa are discussed in their proper places. The other three species, his Taenia ocellata, T. filicoUis, and T. longicollis can best be discussed together and in this connection. The small table shows the distribution of the five species in the hosts from Lake Geneva examined by him. Hosts Proteocephalus Species Coregonus Taenia Taenia Taenia fera longicollis ocellata torulosa Salmo unibla T. longicol- lis T. ocellata Taenia sal- monis Trutta T. longicol- T. ocellata umhlae variabilis lis Perca T. ocellata Taenia fluviatUis filicoUis Esox lucius T. ocellata Lota vulgaris T. ocellata T. torulosa Alhurnus T. torulosa lucidus The Taenia filicoUis of Zsehokke 's description (1884:16-17) is from Perca fluviatUis and may be the same as the specimens from the same host species received by Dr. H. B. "Ward from Professor Parona which La Rue (1911) has named P. dubius. It is certain that Zsehokke 's de- scription and drawings of his specimens from this host do not agree with Schneider's specimens of P. percae (Miiller). The specimens of T. ocellata which Zsehokke reported from Perca fluviatUis are probably only longer specimens of his T. filicoUis. The specimens reported by him from Esox lucius were probably Proteoceph- alus esocis Schneider. It is doubtful if Lota vulgaris harbors the same species of parasite as does the Salmonoid fishes. Zsehokke 's report on 72 ILLINOIS BIOLOGICAL MONOGRAPHS [72 this point needs confirmation. The Taenia longicollis and T. ocellata from Coregonus fera are probably identical. Zschokke's description of his Taenia longicollis was no doubt based on specimens from Coregonus fera for he wrote (p. 14) : "Pendant mes recherches je I'ai trouve en grande quantite dans les appendices pyloriques et dans les intestines greles de Coregonus fera, et une fois, en Fevrier, enkyste sous sa forme larvaire dans le foie de Salmo Umbla." Fortunately Dr. H. B. "Ward has received some specimens from Professor Zschokke labelled, ^'Taenia ocellata, Coregonus fera." These have been found to be identical with Kraemer's Taenia ocellata from Coregonus fera, Lake Lucerne, and they have proved to be a new species to which the writer (La Rue 1911) gave the name of P. fallax La Rue. It is highly probable that the specimens from Coregonus fera identified by Zschokke (1884) as T. longicollis belong to this same species. The T. longicollis of his description differs from that of Kraemer (1892) chiefly in length. The small head, large cirrus-pouch, the proportions of the proglottids, position of the genital pore, and the size of the cirrus- pouch agree pretty well with the facts for P. fallax La Rue. Zschokke (1884) presented no data to show that he had made a comparative study of the specimens collected by him from Salmo umhla and from Trutta variabilis. It is scarcely possible to determine where these specimens belong, and speculation without some basis of fact is worth but little. Kraemer (1892) as a result of his study of specimens taken from Coregonus fera, Lake Lucerne, in July, identified these specimens as Taenia filicollis Rud. Later in the same season (about Sept. 1) he took more specimens from Coregonus fera. These he identified as Taenia ocellata on account of their greater length. His specimens collected in July measured 30-60 mm. Those taken by him in September measured as much as 100 mm. Kraemer now made a careful comparison of these two forms. He found that they agreed in every particular as to size of the head and suckers and as to the presence of a fifth sucker. In the internal anatomy of the proglottids and in the histological structure of the organs the two forms also agreed perfectly. Moreover among his specimens he found gradations in length from the shortest to the longest. On these grounds Kraemer concluded that Taenia filicollis Rud. and Taenia ocellata Rud. were one and the same; that in fact the smaller Taenia filicollis was but an incompletely developed Taenia ocellata. Kraemer was correct in concluding that these larger and smaller speci- mens in his possession belonged to the same species. However, his con- clusion has nothing whatsoever to do with Rudolphi's Taenia ocellata and T. filicollis for the very good reason that Kraemer's specimens belonged to neither of Rudolphi 's species. 73] PROTEOCEPHALIDAE — LA RUE 73 Kraemer in his paper gave no adequate reasons for considering that the Taenia filicoUis and Taenia ocellata of Rudolphi were identical. His specimens were neither from Rudolphi 's type host nor from his type locality but from a very different host and locality. Zschokke had ma- terial from Perca fluviatUis yet he described what he considered to be Taenia filicoUis rather than Taenia ocellata from that host. Neither Zschokke nor Kraemer reported parasites from Gasterosteus aculeatiis or G. pungitiiis, neither of which occur in the waters from which their fish came. Kraemer 's specimens beyond a doubt belong to the species P. fallax La Rue. Riggenbach (1896) accepted Kraemer 's conclusion con- cerning the identity of Taenia ocellata and Taenia filicoUis. He appar- ently made no comparative study of the forms. From North American fish Benedict (1900) described a species which he considered identical with Kraemer 's Taenia ocellata and so named it Proteocephalus ocellata (Rud.). That however was a misdetermination, for Benedict's specimens have been shown to belong to another species (see P. exiguus La Rue). Nufer (1905) may have been dealing in part with this species in his statements regarding P. ocellatus and P. longicollis from Coregonus fera. La Rue (1911 :47 6-477) described this as a new species, P. fallax. The material on which this species is based bears the label "T. ocel- lata, Coregonus fera." It was secured from Prof. Fritz Zschokke by Prof. H. B. Ward. It now bears the number 09.9 in Professor Ward's collection. Some of this material was stained in haematoxylin and mounted in balsam. Other specimens were cleared in glycerine. A comparison of these preparations with Kraemer 's description made evident the fact that this species and Kraemer 's Taenia ocellata are anatomically identical. The fact that Kraemer 's specimens were also from Coregonus fera and that doubtless they came from the same locality was one of the considerations which caused this identity to be suspected. Kraemer 's descriptions of T. ocellata will be used as sources of comparative data, all of his data being grouped together. The larger worms at the writer's disposal were unfortunately broken into pieces. One complete strobila measured 27 mm. long with a maximum breadth of 0.459 mm. A small piece in the same lot had a maximum breadth of 1.20 mm. Kraemer reported specimens of T. ocel- lata 30-60-100 mm. long. He reported a breadth of 0.114 mm. for the head and 0.038 mm. for suckers. The last measurement must be that of the sucker opening and not the maximum diameter of the sucker. 74 ILLINOIS BIOLOGICAL MONOGRAPHS [74 Measurements in mm. of seven scolices and suckers may be seen in the following table : No. Breadth of head Length of head Suckers, maximum diameter Fifth sucker 1 2 3 4* 5 6 7 0.187 mm. 0.185 mm. 0.170 mm. 0.185 mm. 0.204 mm. 0.153 X 105 mm. thick 0.187 X 0.153 mm. thick short 0.085 mm. 0.080 mm. 0.064 X 0.064 mm. 0.068 mm. 0.082 X 0.074 mm. not observed 0.079 mm. 0.058 mm. There is here some discrepancy between Kraemer's figures and those of the writer. This may be due to an error in manipulation, to the fact that Kraemer happened to measure a very slender head, or that he happened to measure it in the dorsoventral (the shorter) dimension. As will be noted the diameter of the sucker as given by Kraemer is about the size which the writer gives for the sucker opening. The head (Figs. 23, 150) is somewhat globular in shape. The suckers are situated at or just above the broadest zone and they are directed somewhat anteriad. In the writer's material the head is readily distinguished from the thin neck. The neck is 0.076 mm. broad (Kraemer), or 0.136 mm. broad in the writer's measurements. Kraemer states that it is long but he points out that in stained preparations part of that which appeared to be neck was in reality made up of- young proglottids. In glycerine mounts the neck sometimes appeared to the writer to be as much as 6 mm. long while in stained preparation 2.38 mm. was the maximum length. The first proglottids (Fig. 170) are about quadrate or they may be longer than broad. Kraemer gives the following breadths for the various proglottids : First long proglottids 0.228 mm. broad, the quadrate ante- rior proglottids 0.532 mm., the sexually ripe mid-proglottids scarcely 2.0 mm., the ripest end-proglottids as much as 2.0 mm. The writer's measurements of similar proglottids are as follows: The first proglot- tids 0.136 mm. broad by 0.17-0.30 mm. long, quadrate mature proglottids 0.34-0.46 mm. broad by 0.34 mm. long, the sexually ripe proglottids, 1.19 mm. broad by 1.36 mm. long (only four proglottids of this size were observed). The segmentation of the worm is indistinct, the margins being quite smooth except for very slight indentations at the junction of the segments. The segments are closely joined together. The genital *The opening of the suckers in No. 4 measured 0.042 mm. 75] PROTEOCEPHALIDAE — LA RUE 75 pore is not marked by a papilla. The common genital sinus is marginal, irregularly alternating, and situated near or slightly anterior to the middle of the segment. Kraeraer worked out in considerable detail the structure of the cuticula, the musculature, the parenchyma, the nervous system, the ex- cretory system, and the histological structure of the various internal organs. In the main the writer does not discuss these points, but since some of Kraemer's conclusions are incorrect the errors are indicated when possible. In preparations studied by the writer the testes number 30-35 and they measure 0.037 by 0.053 mm. Kraemer recorded 27-30 testes with a diameter of 0.057 mm. The testes (Figs. 57, 178) lie in a single layer in the field bounded by the ovary, the anterior margin of the proglottid and the vitellaria. The cirrus-pouch is 0.196-0.255 mm. long in fully ma- ture proglottids, where its ratio to the proglottid breadth is 1 :3-l :2. In fully ripe proglottids it is more or less concealed by the uterine pouches. In a few ripe proglottids in which it was not contracted the cirrus-pouch measured 0,370-0.420 mm. in length. Apparently in this species the cirrus-pouch becomes larger after sexual maturity is attained. The cirrus-pouch is slender. Its inner end is slightly curved upward toward the dorsal surface where it is attached to the walls of the dermo-muscular sac by strong muscle fibers. This inner end (Figs. 57, 178) is usually somewhat swollen making a little vesicle. With this vesicle one or two sinuous curves of the ductus ejaculatorius may be seen. Adjacent to the vesicle is the constricted region of the cirrus-pouch. Here even in toto preparations strong circular muscle fibers may be seen. In this re- gion the ductus passes over into the straight slender cirrus* Just beyond this constricted region the cirrus-pouch again dilates a little and here the circular muscle fibers are not prominently developed. From a cir- rus-pouch so constricted the cirrus itself is usually protruded. The length of the incompletely protruded cirrus is about 0.026 mm. Krae- mer states that the cirrus protrudes 2-3 mm. This must be an error, probably typographical, for a cirrus as long as 2-3 mm. would require first a very large cirrus-pouch and, second, many coils of vas deferens within the pouch. Kraemer's drawings and data are not convincing that this is the case. His figure (Fig. 178) shows a protruded cirrus probably not over 0.3 mm. in length. The vas deferens forms a mass of coils at the inner end of the cirrus-pouch. In mature proglottids this knot lies in the mid-field, even reaching past the middle. Kraemer undoubtedly made some errors in his description of the cirrus of this species. Benedict (1900) pointed out these errors thus: 76 ILLINOIS BIOLOGICAL MONOGRAPHS [76 "Kraemer's description is widely different. His drawing shows a tube with hooks, representing the cirrus, and followed by a proglottis-like arrangement, and then several coils of the vas deferens within the pouch. The drawing has an unreal appearance on the first glance. The cirrus, with its curved hooks, is imbedded in the tissue, which must be torn through before it could be protruded. The proglot- tis-like appearance of a portion of the cirrus, as he drew it, was undoubtedly due to the way in which the circular muscles were cut in sectioning. He drew the cavity of the cirrus, into which the cut ends of the circular muscles projected, as the external outline of the cirrus. The coils would be necessary, according to his theory, but are not to be found. He says that the muscles, which he calls "the roots," are for retracting the pouch, which is sometimes thrust outwards for some distance through the opening. This protrusion is really due to an evagination of the free distal end of the inner tube." The female organs in arrangement are typical of the genus. The vagina opens always anterior to cirrus-pouch. Near its opening at a distance of 0.041 mm. according to Kraemer, it possesses a weak sphinc- ter muscle 0.026 mm. long by 0.034 mm. broad over all. In its course to the interovarial space it crosses the bulbous end of the cirrus-pouch or extends beyond the end of the pouch before bending posteriad. The writer has not noted in toto preparations the dilation in the middle por- tion of the vagina as described by Kraemer. There are no coils of the vagina anterior to the ovary. The ovary is bilobed, the lobes connected by a slender mid-piece. The lobes are solid, fairly thick bodies of elon- gated ovoidal shape. In mature proglottids the span of the ovary is about 0.350 mm. In ripe proglottids the ov^ry instead of becoming more elongated and flattened against the posterior wall of the segment shrinks in size and the two lobes become quite closely pressed together in a small triangular space (Fig. 56) -bounded by the posterior proglottid margin and by the walls of thie uterine pouches. This triangular space formed by uterine pouches in the posterior end of the proglottid is a very char- acteristic feature in this species. The vitellaria are sparse follicular glands in the lateral margins of the proglottid. The organs of the interovarial space are probably about as Benedict has described them for his species and not entirely as Kraemer has described them. The writer has not made sections of this form and has been unable to trace the connections of the ducts. Kraemer established the presence of an ootype, an oocapt, and a shellgland. The paired vitelline ducts do not originate as far anterior as Kraemer has figured them. They probably unite to form a single vitelline duct as in other Proteocephalid species where this has been investigated. Kraemer noted in toto preparations that the vagina anterior to the ovarj- was appar- ently divided, one branch going to the ovary. The second tube is prob- ably the uterine passage which can frequently be seen in toto prepara- 77] PROTEOCEPHALIDAE — LA RUE 77 tions and the connections of which can be worked out only in recon- structions of sections. The uterus is a median tube in mature proglot- tids. In ripe proglottids (Fig. 56, 179) there are 6-8 lateral pouches on either side of the median tube. These lie in the ventral field and come to occupy nearly the whole proglottid. By the pressure of the densely packed uterus the vitellaria are pushed farther toward the mar- gins; the testes are pushed close to the dorsal surface and the shrunken ovarie? are crowded into a small triangular space in the posterior part of the segment. The ripe proglottid is practically a thin walled sac divided up into compartments by the thin septa of the uterine pouches. The eggs are discharged through 2-3 uterine pores (Figs. 56, 179) or through a rift down the ventral surface which is caused by a further splitting of these uterine pores. The usual number of uterine pores is 2 or 3 but occasionally a proglottid is found with a single pore. Krae- mer describes a single uterine pore in the middle of the segment. The eggs have a shell with three membranes, the outer hyaline, variable in size, a middle heavier and more granular membrane, and an inner thin membrane enclosing the embryo. The embryos measure 0.031-0.0336 mm. in diameter. Such a wide variation is probably due to the different forms which the embryos assume. Some are spherical, others ovoidal. The middle membrane measures 0.036-0.041 mm. These measurements show very well the limits of variation. The outer membrane was not measured. This species is readily differentiated from P. percae by its smaller head and suckers, more slender neck, and smaller proglottids. It is less robust than P. percae. It differs from P. percae in having a much shorter cirrus-pouch, fewer testes, a shorter ovary, and larger embryos. It is readily distinguished from P. torulosus by its smaller size and by its lack of a fifth sucker. It differs from the P. longicollis (Rud.) as de- scribed by von Linstow in having a smaller head with much smaller suckers. In the P. longicollis of von Linstow the testes are much larger than in P. fallax and they are in two ( ?) fields. The cirrus pouch is shorter in P. longicollis. The lateral pouches of the uterus are fewer in number and the embryos are smaller than in P. fallax. P. fallax varies from the P. cernuae in being more slender, with a smaller head and less muscular suckers. The latter species has broader but narrower pro- glottids, a shorter cirrus-pouch, more numerous and much larger testes, a longer span of ovary, and smaller embryos. P. fallax differs from P. flicollis (Rud.) in being longer, in having a fifth sucker, a longer cirrus- pouch, fewer testes, and larger embryos. P. fallax much resembles P. exiguus but it differs from that species in having a larger head, larger suckers, a larger fifth sucker, a longer 78 ILLINOIS BIOLOGICAL MONOGRAPHS [78 neck, more numerous and larger proglottids, fewer testes, a shorter cir- nis-pouch, and fewer uterine pouches. The embryos are larger than in P. exiguus. This species resembles P. pusUlus Ward. It differs from that species in the character of the segmentation, in the smaller size of its suckers, in the position of the genital aperture, in the smaller number and size of testes, in its longer cirrus-pouch and in its fewer uterine pouches. P. fallax resembles P. agonis Barbieri but it differs from that species in being somewhat larger, in having a fifth sucker, fewer testes, and more uterine pouches. P. fallax is larger than P. esocis (Schneider) and it has a fifth sucker. It moreover has smaller and less numerous testes than P. esocis. P. fallax most closely resembles P. duhius but it differs from that species in having smaller and much fewer testes, a relatively shorter cirrus-pouch, fewer uterine pouches, a slightly smaller embryo, and a smaller middle egg membrane. In size, in size of head, and size of suckers they resemble each other remarkably. PROTEOCEPHALUS NEGLECTUS La Rue [Figs. 81, 82] 1911 : Proteocephalus neglectus La Rue 1911 :477 Specific Diagnosis: Characters of genus. Strobila incomplete. Head, suckers, neck not observed. Outline of proglottid rough. Seg- mentation evident. Genital pore on a slight prominence. Ripe proglot- tids 0.5 mm. long by 0.93 mm. broad to 0.75 mm. long by 1.53 mm. broad. Young and mature proglottids not observed. Genital pores irregularly alternating, situated near middle of lat- eral margin of proglottid. Cirrus-pouch frequently contracted, 0.185- 0.265 mm. long by 0.080 mm. broad. Normal cirrus-pouch 0.340 mm. long. Cirrus and ductus ejaculatorius straight. Vas deferens a mass of coils in mid-field of proglottid. Testes about 75, spheroidal, 0.042- 0.064 mm. in diameter, situated in a single layer in space between vitel- laria. Vagina anterior to cirrus-pouch, its opening dorsal to opening of cirrus-pouch. Sphincter vaginae poorly developed, situated near vaginal opening. Vagina crosses cirrus-pouch near middle. Receptacu- lum seminis not observed. Ovary bilobed, lobes with smooth outlines, clubshaped. Organs of interovarial space not observed. Vitellaria lat- eral, follicular. Vitelline follicles small, compacted. Uterus with 7-9 lateral pouches on either side. Uterine pores not seen. Embryo 0,026- 0.0265 mm. in diameter. Outer egg membrane 0.042-0.047 mm. Habitat: "Forelle" (Trutta fario), type host, probably from Lake Geneva or Lake Lucerne, Switzerland. 79] PROTEOCEPHALIDAE — LA RUE 79 Type: Bottled material No. 09.10 in Dr. H. B. Ward's collection, and slides of same. Some pieces of strobila without heads were received by Dr. H. B. Ward from Professor Zschokke of Basel. These were labelled ^'Taenia longicollis Rud., aus Forelle, Zschokke." The bottle is now No. 09.10 in Dr. H. B. Ward's collection. Four toto unflattened preparations were made from this material. This material formed the basis of the prelimi- nary report, La Rue (1911 :477). Head, suckers and neck were not seen. A proglottid with eggs in the uterus measured 0.5 mm. long by 0.93 mm. broad. A ripe proglottid very full of eggs was 0.75 mm. long by 1.53 mm. broad. The outlines of the segments are rough, with several indentations on the margin of each. Proglottid limits are well defined by the indentation at the corners and by the rounded corners. A slight prominence bears the genital pore. Genital pores alternate irregularly in the strobila. They are situ- ated one in the middle of a lateral margin of each segment. This genital pore leads into a common atrium into which the cirrus-pouch and vagina open. When the cirrus is partly protruded the cirrus-pouch is con- stricted near its inner end (Fig. 81). It is also reduced in length, meas- ing in various states of contraction 0.185-0.190-0.220-0.265 mm. by a maximum breadth of about 0.080 mm. In a single proglottid the cirrus- pouch was in a normal condition. This is delineated (Fig. 82). This cirrus-pouch measures 0.390 mm. long. The length of the cirrus-pouch is about 14-3^ the breadth of the proglottid. Sometimes the cirrus is somewhat protruded tho it has not been seen completely protruded. It is blunt at the tip. Within the cirrus-pouch the cirrus and ductus ejaculatorius are straight. The one passes imperceptibly into the other. Coils of the vas deferens cannot be seen clearly but their confused out- lines may be discerned in the middle region of the proglottid left vacant by the testes. The testes numbered 75 and 76 respectively in two pro- glottids in which they were counted. They are spheroidal, 0.042-0.053- 0.064 mm. in diameter. It seems that they lie in one plane, filling the space between the vitellaria anterior to the ovary. The uterus (Fig. 81) is made up of a median ventral tube from which 7-9 lateral pouches arise on either side. No uterine pores were discovered. The vitellaria are follicular and situated near the lateral margins of the segment. The follicles are small and quite compact. In the present species the vitellaria are less well developed than in P. cer- nuae. The ovary is bilobed and is posteriorly situated. The lobes are long, thick and heavy, and have smooth outlines. In ripe proglottids the span of the ovarian lobes may be 0.60 mm. The vagina (Fig. 82) tho apparently situated anterior to the cirrus-pouch has its opening into 80 ILLINOIS BIOLOGICAL MONOGRAPHS [80 the genital atrium directly dorsal to the cirrus-pouch. Near its opening there is a small sphincter vaginae 0.016 mm. long by 0.010 mm. thick. Normally in its course the vagina is slightly bowed posteriad across the middle or the inner end of the cirrus-pouch. The course of the vagina in toto preparations cannot be traced to the interovarial space. The organs of the interovarial space have not been studied. The embryos measured 0.026-0.0265 mm. in diameter, the outermost envelope 0.042- 0.047 mm. The second membrane was not measured. In some respects the present species resembles P. fallax La Rue. The triangular shape of the interovarial space of ripe proglottids is much alike in the two species. So also there is considerable resemblance in respect to the uterine outpocketings. The proglottids, however, are as a rule broader and shorter in the present species. In the number of the testes and their close proximity to each other this species is very differ- ent from P. fallax. The cirrus-pouch tho greatly resembling that of P. fallax is relatively shorter. The two species are alike in the character of the vagina and the sphincter vaginae. Ovaries are larger in the pres- ent species. The best characters for distinguishing the two species are the number and size of the testes, the relative size of the cirrus-pouch and the size of the embryos. In some respects this species resembles P. duhius La Rue but the ripe proglottids are a little larger and somewhat thicker in the present species. The cirrus-pouch in proglottids of the same stage of development may be of nearly the same length. This species has more testes and these are smaller than in P. dubius. The chief difference lies in the size of the embryos. This difference amounts to 0.005-0.007 mm. The second membrane of the eggs of P. dubius is larger than the outer membrane of eggs of P. neglectus. The present species differs from P. percae in the length of the cir- rus-pouch, in the proportions of the proglottids, number and size of the testes, and in the size of the embryos. P. neglectus differs from P. lon- gicollis as described by v. Linstow in the number, size and arrangement of the testes. The arrangement of the testes of P. longicollis in two fields sets that species apart from all the other species reported from fish, if von Linstow 's observations on that point are correct. P. neg- lectus further differs from that species in the number of uterine pouches and in the position of the genital pore. P. neglectus does not agree well with Zschokke's (1884:14-16) description of Taenia longicollis Rud. from Coregonus fera. The form which he described is apparently iden- tical with the P. fallax La Rue which occurs in the same host species. 81] PROTEOCEPHALIDAE — LA RUE 81 PROTEOCEPHALUS DUBIUS La Rue [Figs. 20-22, 75-77, 147-149] 1884 1884 1911 Taenia filicollis Zscliokke 1884:16-17 Taenia ocellata Zschokke 1884:13-14 in part(?) Proteocephalus dubius La Rue 1911:476 Specific Diagnosis: Characters of the genus. Small cestodes as much as 40 mm. long by 0.80-1.20 mm. broad. Segmentation indistinct. Proglottids about 100 in number. Head small, variable in shape, well set off from neclf. Length of head 0.10-0.14 mm., breadth 0.127-0.212 mm. Four sucliers 0.069-0.080 mm. in diameter, cavities deep, sucl^er outlines round or irregular. Fifth sucker 0.026-0.037 mm. in diameter. Neck slender 1.8-3.0-3.5 mm. long by 0.085-0.140 mm. broad. First pro- glottids broader than long, 0.20 mm. broad by 0.050 mm. long. IVIature proglottids quadrate, broader than long, or longer than broad, 1.02 mm. long by 0.34 mm. broad to 0.595 mm. long by 0.680 mm. broad. Ripe proglottids quadrate, broader than long, or usually longer than broad, 1.19 mm. long by 0.680 mm. broad to 0.680 mm. long by 1.02 mm. broad. End-proglottid, triangular, small, functional. Genital opening marginal, near middle of proglottid or anterior thereto, irregularly alternating. No genital papilla. Testes in two lay- ers between vitellaria, anterior to ovary, 55-60 in number. Vas deferens a mass of coils in mid-field. Cirrus-pouch long, slender, 0.265-0.370-0.425 mm. in length by 0.070-0.085 mm. in breadth. Ratio of length of cirrus- pouch to proglottid breadth 5:11-1:2. Cirrus slender, straight, when protruded short and slender. Ductus ejaculatorius straight. Vaginal opening anterior to cirrus-pouch. Sphincter vaginae weak, situated near vaginal opening. Vagina crosses cirrus-pouch near middle. Ovary bilobed. Lobes thick somewhat quadrate in nearly mature pro- glottids, smoothly ovoidal in fully mature and past-mature proglottids. Vitellaria lateral, sparse, follicles small. Uterus with 7-10-12-14 lateral pouches on either side. Uterine pores 1-2 on ventral surface. Eggs with three membranes, second membrane granular, thick, 0.042-0.053 mm. in diameter. Embryos about 0.032 ram. in diameter. Habitat : Intestine of Perca fluviatUis (type host) ; Lake Geneva (type locality). Perhaps this species may occur also in the same host species of other lakes and rivers in southern or central Europe. Zschokke (1884:16-17) described some specimens of cestode found by him in Perca fluviatUis from Lake Geneva. In some respects his description agrees fairly well with P. fallax La Rue from Coregonus fera. However in regard to the ovary there is considerable difference. 82 ILLINOIS BIOLOGICAL MONOGRAPHS [82 Moreover it scarcely seems probable that Perca fluviatilis and Corego- 71US fcra normally harbor the same parasitic species. With this doubt in mind some material which Dr. H. B. Ward has received from Pro- fessor Parona labelled Taenia ocellata from Perca fluviatilis was care- fully investigated. It was found that this material which at first glimpse appeared to be identical with P. fallax La Rue from Coregonus fera was after all sufficiently different to make it a separate species which was described by La Rue (1911:476) from material on which the present description is based. Material studied was alcoholic material in Professor Parona 's collection labelled ^'Taenia ocellata, Perca fluvia- tilis," locality not known, and slides and alcoholics of the same in Prof. H. B. Ward's collections. These cestodes are of small size, being short and slender. The longest specimen in Professor Parona 's material measured about 40 mm. in length by about 0.80-1.2 mm. in maximum breadth. In such a specimen there are about 30 proglottids with eggs in the uterus, 12-18 mature proglottids, about 30 which show more or less developed sexual organs, and very few in which the anlagen of the sexual organs cannot be seen, in all about 80-90 proglottids. Segmentation is not very dis- tinct for the proglottids are joined by nearly their entire breadth. The corners are slightly rounded. Zschokke stated that the margins of the proglottids are not rounded and their angles are somewhat rounded; that the animal never presents a crenated appearance and that it has the appearance of a ribbon. Zschokke found from 60-100 segments in the strobila. His longest specimen was about 4 cm. long and about 1 mm. broad. The head (Figs. 147, 148) is of small variable shape, well set off from the neck. Frequently its anterior face is somewhat conical, at other times flattened. The head is flattened dorsoventrally. Its length varies from 0.100-0.140 mm. Its breadth is from 0.127 mm. in heads turned slightly sidewise to 0.212 mm. in slightly swollen heads. At its broadest part the head bears four suckers which are directed outward and upward. These suckers appear to be variously placed on the head depending on the state of contraction. A small fifth sucker 0.026-0.037 mm. in diameter is situated at the apex of the head. The four suckers vary in size from 0.069-0.080 mm. in diameter. They are usually nearly circular in outline but may be a little irregular. The cavity is deep and irregular in shape or it may be nearly round in outline. The neck is slender, 1.8 mm. to 3.0-3.5 mm. in length by 0.085-0.140 mm. in minimum breadth. The length of the neck was determined by measur- ing from the head to the first segmentation visible in stained prepara- tions. 83] PROTEOCEPHALIDAE — LA RUE 83 The following table shows dimensions of neck, head and suckers in millimeters : Neck Head Suckers /if^^^ Sucker Length Breadth Length Breadth Diameter 1.8 3.4 ? ? 3-3.5 0.130 0.085 0.140 0.130 0.130 0.12-0.140 0.130 0.100 ? 0.130 0.144 0.12r 0.159 0.212 0.148 0.080 0.079 0.069 0.069 0.069 0.074 0.074 0.074 0.069 0.069 0.026 0.037 0.037 0.033 0.032 Zschokke's (1884) description, of the head, suckers and neck reads: "La tete est petite, distincte du cou, arrondie en-avant. Son pourtour est garni de quatre ventouses dont la position relative est fort variable (see Figs. 147-148). "Ces organes de fixation sont tres profonds et pourvus d'une puissante mus- culature. Quelquefois ils sont reunis sur une de faces, de maniere qu'on peut les voir de face tous les quatre a la fois. Frequemment elles font saillie au dela des pourtour de la tete. Celle-ci prend alors une forme libee ou frangee fort variable selon le degre de contraction des ventouses. La tete presente ainsi souvent des preeminences distribuees regulierement, Les ventouses peuvent meme aflfecter la forme de petites trompes protractiles. "Le cou est long, filiforme, epaissi en-arriere; il n'occupe cependant jamais plus d'un cinquieme ou d'un quart de la longueur totale de I'animal, tandis que chez le Taenia longicollis il atteint facilement un tiers." There is pretty good agreement between his description and the writer's. In the writer's specimens the first proglottids are broader than long, 0.20 mm. broad by 0.05 mm. long. These soon elongate somewhat and then the anlagen of the genital organs begin to appear. The proglottids as they become mature elongate and also increase in width. They may be much elongated, nearly square or broader than long depending upon the state of contraction. In the same strobila the following measurements were taken from anterior to posterior some few proglottids being omitted at intervals, measurements of length being stated first in each instance: 1.02 by 0.34 mm.; 0.68 by 0.425 mm.; 0.595 by 0.425 mm. ; 0.510 by 0.595 mm. ; 0.595 by 0.680 mm. The last measurement is of the last proglottid without uterine eggs. Ripe pro- glottids may be nearly square, longer than broad or broader than long. They may measure as much as 1.19 long by 0.68 mm. broad; 0.68 by ^Head turned slightly sideways. 84 ILLIXOIS BIOLOGICAL MONOGRAPHS [84 1.02 mm.; 0.68 by 0.85 mm. The end-proglottid is triangular in out- line, the posterior end being rounded. It is 0.425 mm. broad by 0.476 mm. long. Apparently it is functional. No excretory pore could be seen at its posterior end. Of the proglottids Zschokke wrote: "Les premiers articles sont courts, deux a trois fois plus larges que longs. Les suivants deviennent carres et les derniers sont ordinairement plus longs que larges. L' article terminal est arrondi en arriere. Les bords des proglottis ne sont pas bombes; leurs angles sont tres peu emousses. L 'animal ne presente ainsi point de crenulure; il a 1 'aspect d'un niban." The genital opening which is situated near the middle or slightly anterior to the middle of the lateral margin of the proglottid alternates irregularly. There is no genital papilla. The testes (Figs. 75, 77) are nearly round or at times slightly compressed. They measure 0.063- 0.079 mm. in diameter and they are situated in two partial layers which cover the entire field betweeq the vitellaria anterior to the ovary. Their number is from 55 to 60. The vas deferens forms a small com- pact mass of coils in the midfield of the segment. The cirrus-pouch (Figs. 75, 76, 77) is long, quite slender, smooth in outline or at times somewhat constricted near the inner end by the contraction of circular muscle fibers. The cirrus-pouch measures 0.370-0.425 mm. long in ripe proglottids, 0.265-0.292 mm. long in a proglottid with few uterine eggs and 0.228-0.265 mm. in mature proglottids where the cirrus is being protruded. Its breadth is about 0.070-0.085 nmi. It extends from 5/11 to ^ across the proglottid breadth or in some cases it may extend slightly past the middle. The cirrus is straight and slender. When protruded it may extend aboat 0.1 mm. past the margin of the segment. The protruded cirrus is slender or, if but slightly protruded, conical. The ductus ejaculatorius is straight and of the same size as the cirrus of which it really forms a part. The vagina opens into the conmion genital sinus apparently ante- rior to the cirrus-pouch. Near its opening it possesses a small sphincter vaginae. The course of the vagina is slightly anteriad then posteriad and mesad in a long arc which crosses the cirrus-pouch near the middle of its dorsal side. Its entire course into the interovarial space has not been traced. A receptaculum seminis has not been observed. The ovary is posterior and is bilobed, but in nearly mature proglottids the mid-piece may not be visible. The lobes (Fig. 75) may appear as more or less irregular quadrate bodies in the posterior comers of the segment. In such a condition they resemble the ovaries which Zschokke delineated. His figure is reproduced (Fig. 149). In more mature and ripe proglottids the lobes of the ovary are smoother in contour (Figs. 85] PROTEOCEPHALIDAE — LA RUE 85 76, 77). The ovarian lobes in ripe proglottids have a span of 0.425 mm. The lobes are heavier and thicker than in P. fallax. The organs of the interovarial space have not been observed. In the lateral fields of the proglottid lie the vitellaria, made up of small loose follicles. Well-filled uteri (Fig, 76) are made up of a median tube and 7-8-10-12 or even 14 irregular lateral pouches on either side. The more common number of pouches is 8 or 9. One large ventral uterine pore occurs quite regularly near the middle of the proglottid and a smaller pore can sometimes be found farther anteriad. Uterine eggs have three membranes. An outermost hyaline membrane is variable in size and was not measured. The second membrane is thicker, is granular and more nearly spherical. It has a diameter of 0.042-0.048-0.053 mm. tho its more common dimension is 0.048 mm. An innermost thin membrane immediately invests the embryo. The embryo has a diameter of about 0.032 mm. but when elongated it may measure 0.026 by 0.037 mm. or even 0.032 by 0.037 mm. The average measurement is about 0.032 mm. Zschokke's description of the genital organs reads thus: "Les orifices genitaux se trouvent au fond d'un bourrelet circulaire, situe au milieu ou un peu au-dessus des bords lateraux. L'alternance de la position a gauche ou a droite est irreguliere. Les cirrhes sont courts, coniques, leurs poches, etroites. Rudolphi parle de ovaria quadrangularia ; en effet le parenchyme est rempli de vesicules, qui, dans les articles jeunes, ont une forme ronde ou ovalaire et deviennent, dans les proglottis plus murs, carrees et anguleuses. En realite ces vesicules sont a I'etat normal pyriformes ; leur aspect carre est le resultat de leur pression reciproque. Du reste ce ne sont pas des ovaries, ce sont des testicules dont chacun presente un petit canal deferent. Tous ces canalicules se reunissent dans un canal excreteur commun. "Deja Dujardin, en citant la description de Rudolphi, met, derriere "ovaires opaques, egalement carres", un point d'interrogation et Diesing n' en parle plus. "Le vagin est court, il aboutit a une poche seminale assez spacieuse. L'uterus sous forme d'un tube large suit la ligne mediane du proglottis et se rend en decrivant quelques faibles lacets vers le bord posterieur de I'article. La il decrit un noeud de lacets et se divise enfin en deux branches, qui, de leur cote, con- stituent a droite et a gauche une masse d'ovaires lobes ou contournes. Entre les ovaires, touchant le bord posterieur du proglottis, se trouve le glande vitellogene. Des amas glandulaires, peut-etre la continuation directe des vitellogenes, se trou- vent le long des bords lateraux." This species is much smaller than P. percae (Miiller). It is most closely related to P. fallax from Coregonus fera. It differs from that species in having regularly a larger number of testes (about twice as many as are found in P. fallax) and these are also larger. In P. fallax the testes are in one layer, in this species in two partial layers. The cirrus-pouch is usually longer than in P. fallax and it is relatively 86 ILLINOIS BIOLOGICAL MONOGRAPHS [86 longer in proportion to the proglottid width. The uterine pouches may be more numerous and the embryos a trifle larger than in P. fallax. The second egg membrane is larger in this species. In other respects the species are much alike. Staining and careful comparisons are nec- essary to distinguish them. P. duhius may be differentiated from P. neglectus by the smaller size of its proglottids and by the larger size of its embryos. The proportions of the cirrus-pouch are also very differ- ent. P. duhius is much unlike P. percae and P. cernuae in size, in size of suckers ; in number and size and arrangement of testes, and in length of cirrus-pouch. This species differs from P. esocis, P. agonis and P. filicollis in size and in the presence of a fifth sucker. There is also con- siderable difference in the length of the cirrus-pouch. PROTEOCEPHALUS CERNUAE (Gmelin) La Rue [Figs. 5, 6, 66-68] 1790: Taenia cernuae Gmelin 1790:3079, No. 79 1803: Halysis cernuae Zeder 1803 :376 1810: Taenia ocellata Rudolphi 1810 :108, in part t> e o * " 5 ** h ^ c «> .s E . .-o .2 BE!; Q E E » iSE •5E 03 = 00 Es u O ti gE -E 2e -4E o o t3 E o u bo c *^ o 3 a.^ U <» u in ^* *5 Kt3 u •^E j; o t> M A vo i5 2 u 2 > «Q ®t^ . - '^ u »3 E « boiu-o £ « ctJ'S *" Ec E o 2 1) CB ■« c c c n ^ • ,-• ""o uEEeS iJEEgs « i; I-) oo o V ^ - R •o B o ki « oi > 10 J3 13a •d V S ES •s-g 00* E °^ E J3 £ tis-^ K 60 C o C pi n -""Se !/» R U" E •^5^2 o 1^ 3 ^ ^ ;-^ 1 u v 2E a; u 107] PROTEOCEPHALIDAE—LA RUE 107 §2 •S 8 OT a. hi c o S >> bi E 5.^ E 00 00 E E "O ^ OJ »>. V E o <»> &E o o < a. JJ— M «^ c B c o be B bi c E-^s ^ c *< <7\ B b O C O. 9 c on _ . Oo <« o « g, bo . p 00 Se SE 4.9 u-lO u w 3 >. ±1 o o o'53 41 5: c Q *< 0;3 v'o. O. o ^ E ° G o ^ E •* u la n) 4) u bOT3 .s ., C C o V 3 t| O i- ti . o O . a <-5 E u o 2 JE m 0\ vo bco Wo d ;? be u o u S bo o C rt o *o "It «d K 2 V 3 . 0) ^^ o o "-"^ O Q. CO "^u^ 2 Co S V « P"* •S.oS .S?iE i: o m 60'" O 3 r c< o bo o •Sou E ^ S:hs 2;E.t: u •* ;s V fi ti V a cd 09 •OS V -1 c E E E g^ U E E PI •o •o 00 be o cj c •"* 3 5 0) lO o O Id wo Tl- _o "o M a I **< e 1|6|E wS O ^ 88a 108 ILLINOIS BIOLOGICAL MONOGRAPHS [108 An examination of the preeeeding table makes evident that the differences between Schneider's Proteocephalus percae and his P. oceU latus are so slight that one would not be justified in considering these forms as varieties. Schneider dealt with a single species which ac- cording to the rule of priority should be known as Proteocephalus percae (MiiUer). Proteocephalus percae in some respects resembles P. agonis Bar- bieri, P. exiguus La Rue and P. pusillus Ward. It, however, is so much larger than these species that the possibility of an identity is entirely precluded. P. percae in many ways resembles P. fallax La Rue but it is larger than that species. The character of its proglottids is greatly different. P. percae has many more and larger testes, a longer cirrus- pouch, a much larger ovary, more voluminous vitellaria, a larger head, larger suckers, and larger sucker openings. P. fallax has a larger num- ber of preformed uterine pores. It also has larger embryos. The area occupied by the ovaries of ripe proglottids is triangular in P. fallax but much elongated in P. percae. P. percae resembles P. cernuae in the size of the head, in the size and character of the fijth sucker, in the shape of the ovary, and somewhat in the character of the proglottids. P. percae, however, has larger suckers with larger sucker openings, a longer and more slender neck, a much longer cirrus-pouch, and fewer and smaller testes. The relationship of cirrus-pouch and vagina are greatly different in the two species. In P. percae the vagina crosses the cirrus- pouch near the middle of the latter while in P. cernuae the vagina does not cross the cirrus-pouch. P. cernuae may have more uterine pouches and its embryos are larger than in P. percae. Further points of dif- ference between P. percae and P. cernuae may be readily noted in an examination of the comparative table of Proteocephalus species (vide infra). P. percae in some respects resembles P. longicolUs as described by von Linstow but it differs in the number of uterine pouches, number of testes, length of cirrus-pouch, a'nd in the size of eggs and of suckers. P. percae most closely resembles P. pinguis La Rue. The heads of the two species are of about the same size. The suckers are much alike but the fifth sucker is much better developed in P. pinguis than in P. percae. P. pinguis is more slender, its proglottids more nearly quadrate and thicker than in P. percae. P. pinguis has many more uterine pouches and preformed uterine pores. Its cirrus-pouch is less than half as long as that of P. percae. P. percae is readily differentiated from P. torulosus by reason of the total lack of a fifth sucker in the latter. In number of uterine pouches, length of cirrus-pouch and in numerous other ways these species are very dissimilar. 109] PROTEOCEPHALIDAE—LA RUE 109 PROTEOCEPHALUS LONGICOLLIS (Zeder) [Figs. 167-169] 1780: Taenia eperlani Acharius 1780 :3080 1789: Taenia salmonis Wartmanni Frolich 1789 :24 1790: Taenia Froelichii Gmelin 1790 :3080 1800: Alyselminthus longicollis Zeder 1800:258. 1802: Taenia longicollis Rudolphi 1802a :113 1803: Halysis longicollis Zeder 1803 :333 1803: Taenia Renkina Schranli 1803 :242 1810: Taenia longicollis Rudolplii 1810:107 1810: Scolex tetrastomus Rudolplii 1810:6 1819: Taenia longicollis Rudolplii 1819 :149 1845: Taenia longicollis Dujardin 1845 :585 1850: Taenia longicollis Diesing 1850 :512-513 1891: Taenia longicollis V. Linstow 1891 :565-576 1891: Tetracotylus longicollis IVIonticelli 1891 :162 1894: Ichthyotaenia longicollis Lonnberg 1894:803 1911: Proteocephalus longicollis La Rue 1911 :475 Specific Diagnosis: Characters of genus. Cestodes of small size. Observed length as much as 20-200-464 mm., breadth 1-2-2.25 mm. Scolex 0.43 mm. broad, length (?). Necls: 0.3 mm. broad by 3.2 mm. long. Suckers circular, 0.12-0.14-0.18-0.19 mm. in diameter. Fifth sucker half as large as others. First proglottids 0.43 mm. long by 0.71 mm. broad. Proglottids at end of first third of strobila 0.53 mm. long by 0.99 mm. broad. Posterior proglottids 1.03 mm. long by 0.83 mm. broad. End proglottid triangular. Genital pore marginal, irregularly alternating, situated at end of anterior one-fourth of proglottid. Testes spheroidal, 0.09 mm. in diam- eter, 25 in each segment, arranged in two( ?) fields near vitellaria. Vas deferens forming a close mass in the median field of proglottid. Cir- rus-pouch spindle-shaped, muscular, 0.110 mm. broad, extending just through vitellaria. Cirrus club-shaped when everted, reaching 0.2 mm. past margin of segment. Ovary bilobed, posterior. Lobes slender, united by a midpiece. Vitellaria lateral, follicular. Uterus with three lateral pouches on either side. Vagina anterior to cirrus-pouch, not crossing same. Sphincter vaginae? Receptaculum seminis? Unripe eggs 0.0156-0.0196 mm. in diameter. 110 ILLINOIS BIOLOGICAL MONOGRAPHS [110 Habitat: In intestine of host. Host Coregonus (Saliiio) lavaretus Qoregonus {Saltno) maraenula = C. albula Coregonus (Salmo) wartmann't Coregonus (Salmo) wartmanni Coregonus wartmanni nobilis Coregonus fera Coregonus fera Coregonus albula Coregonus schinzii helveticus Coregonus exiguus albellus Osmerus eperlanus Osmerus eperlanus Osmerus eperlanus Trutta trutta Trutta trutta Trutta fario Salmo thymallus^ Thymallus vulgaris Salmo thymallus = Thymallus vulgaris Salmo alpinus Salmo salvelinus Salmo salvelinus Salmo umbla Esox lucius Esox lucius Perca fluviatilis Alburnus lucidus Squalius cephalus Squalius leuciscus Locality Greifswald Berlin Lake Lucerne Lake Geneva Rositten, East Prussia Nicolaiken, East Prussia Lake Lucerne Lake Lucerne Berlin (in Museum Vienna) Lake Lucerne Lake Geneva Lake Balaton Lake Lucerne Lake Lucerne Lake Lucerne Lake Lucerne Lake Lucerne Collector Rudolphi Rudolphi Frolich Schrank Nufer Zschokke Miihling Miihling Nufer Nufer Acharius Rudolphi V. Linstow Frolich Zeder Martin Rudolphi Bremser Martin Nufer Zschokke von Ratz Nufer Nufer Nufer Nufer Nufer Authority Rudolphi, Rudolphi, Rudolphi, Rudolphi, Nufer, Zschokke, Miihling, 1810:107. 1810:107. 1810:107. 1819:495. 1905 :75 1884:11,14-16. 1898 :36. Miihling, 1898 :36. Nufer, Nufer, Rudolphi, Rudolphi, v. Linstow, Rudolphi, Rudolphi, Rudolphi, Rudolphi, 1905 75. 1905 75. 1810 :2i2. 1810:107, 1891 :56s-576. 1810:107. 1810:107. 1810:107. 1810:107. Rudolphi, 1819 :49s. Rudolphi, v. Linstow, Nufer, Zschokke, von Ratz, Nufer, Nufer, Nufer, Nufer, Nufer, 1810:107. 1878 :262. 1905 75- 1884:11,14-16. 1897:159. 1905 75- 190S 75. 1905 75. 1905 75. 1905 75- Possibly this species is the form which was originally referred to by Acharius (1780:52) who called it Taenia eperlani. Acharius 's de- scription and diagnosis of this form are not accessible to the writer. Despite the fact that Rudolphi (1810:212) considered that this species could not have been a synonym of Taenia longicollis Rud. it seems that it must be a Synonym of the latter species or else some of the host records of Ill] PROTEOCEPHALIDAE—LA RUE 111 Rudolphi and others are open to question. Concerning this species Ru- dolphi (1810:212) wrote: "In Salmonis Eperlani cavo abdominis Taeniam reperit (pro Fasciola habi- tam) quatuor ad quinque lineas longam, capite oblongo obtuso; osculis duobus superioribus anticis (totidem inferioribus in figura latentibus) orbicularibus exi- guis ; collo nuUo ; articulis transversis, obtusis. Cum collum nullum delineatum sistatur, pro Taenia longicolli (n. 20) eodem in pisce obvia vix haberi potest, huic enim longissimum conceditur." Frolich (1789:24) named a species Taenia salmonis Wartmanni which is recognized by Rudolphi ( 1802a :113 and 1810 :107 ) as a synonym of Taenia longicollis Rud. Frolich 's description, if he gave one, is not accessible to the writer. The name with which he designated the species is unavailable on account of its trinomial character. Gmelin (1790: 3080) gave a diagnosis of Taenia Froelichii. This species was consid- ered by Rudolphi (1802a :113 and 1810:107) to be a synonym of Taenia longicollis. Gmelin 's diagnosis reads: ''TAENIA FROELICHII. No. 91. — T. capite cum collo longissimo tenuissimo marticulato continuo, ova- riis dendaticis linea laterali cinctis. Froelich Naturf. 24 p. 124. t. 4. /. 20. 21. Habitat in Salmonis Wartmanni intestino duodeno." The name longicollis as a designation for a species of cestode was first used by Zeder (1800:258) in connection with the generic name Alyselminthus. Unfortunately Zeder 's description is not available to the writer who therefore can not judge as to its character. Rudolphi (1802a :113) gave a specific diagnosis of this species which he styled Taenia longicollis. In his synonymy he cited Alyselminthus longicollis Zeder, Taenia Salmonis Wartmanni Froelich, and Taenia Froelichii Gmelin. After a statement regarding the hosts of this form he wrote : "Zeders Beschreibung ist voUkommen geniigend; wenn er Frolich tadelt, weil dieser die baumschenartigen Figuren oder Eyerstocke der Glieder mit zur Bestim- mung des Wurms braucht, so habe ich im AUgemeinen nichts dagegen, dass man sie weglasst. Bey einigen Arten sind sie indessen besonders ausgezeichnet, so auch hier, wo man sie auf den ersten Blick gewahr wird, wesgegen auch die letzten Glieder blaulich, oft sogar schwarzlich aussehen. Wo man erst den Press- schieber zu Hiilfe nehmen muss, um sie zu sehen, darf man ihrer nicht erwahnen, das versteht sich." Rudolphi gave no description of this species at this time nor were there any drawings to accompany his comments. Zeder (1803:333) re- ferred to this species under the name Halysis longicollis. In his syn- onymy he lists Taenia salmonis Wartmanni Frolich, Alyselminthus lon- gicollis Zeder, Taenia Frolichii Gmelin. His diagnosis reads : * ' HALY- y^ 112 ILLINOIS BIOLOGICAL MONOGRAPHS [112 SIS LONGICOLLIS. — leviter crenata; capite cum collo longissimo, lin- eari continuo, tnmcato; osculorum margine prominente." Kudolphi (1810:107) gave a diagnosis and description which is here quoted verbatim: "Taenia longicollis R. Taenia: capite truncato, collo longissimo, articulis subquadratis, ovariis race- mo sis. Frolich im Naturforsch. 24.P.124. Tab4. fig.20.21. Taenia Salmonis Wart- manni. Gmel. Syst. Nat. p. 3080. n. 91. Taenia Froelichii. Zeder Nachtrag p. 258. Alyselminthus longicollis. Rudolphi in Wied. Arch. III. i.p.113. Taenia longic. Zeder Naturg. p. 333. n. 9. Halysis longic. "Hab. in intestinis Salmonum. In Salmonibus Wartmanni plurimis Froelich- ius Aug^sto copiosam; in 5". Trutta Zederus; ego in 5". Lavareto Majo et S. Ma- raenulis plurimis Februario, reperimus. In Salmone Eperlano a se inventas anx Treviranus mecum communicavit. "Descr. Vermes unum ad septum pollices longi, lineam dimidiam vel integram lati. "Caput depressum, truncatum, exiguum; osculis orbicularibus, binis tam su- perioribus, quam inferioribus, capitis margini antico approximatis, ut sub ejusdem motu saepe antica omniaque simul appareant. Colluni cum capite continuum, lon- gissimum, tertiam circiter totius longitudinis partem sibi vindicans, depressum, margine obtuso integerrimo. Corpus depressum, articulus anterioribus brevissimis, reliquis subquadratis, marginibus singulorum antico et postico rectis, lateralibus rotundatis, ut totius vermis latera crenata appareant. Articulus ultimus obtusus. Ovaria in articulis posticis, inde vel caerulescentibus, vel nigrescentibus, distincta, racemosa sive dendritica. "Obs. I. An scolex tetrastomus supra dictus hujus Taenia proles nondum articulata? Sed reliquarum Taeniarum foetus semper articulates vidi, neque caput, neque pars postica acuta conveniunt. "Obs. 2. Hujus speciei cum insequentibus ob articulos margine postico vix incumbentes, ob capitis collique formam, affinitas magna; differentiae tamen spe- cificae singularum discrimen satis indicant. "Obs. 3. An quas Stellerus (Pallas N. Nord. Beytr. I.i, p,i02) in Eperlani vesica natatoria reperit, Taenia hue pertinent? Conf. n. 113." Kudolphi (1819:149) quoted the diagnosis used by him before (Ru- dolphi, 1810:107). He stated that he had found the species in Corego- nus (Salmo) lavaretus at Greifswald, in C. (Salmo) maraenula=C. aU hula and in Osmerus eperlanus at Berlin, that Frolich had found it in Coregonus (Salmo) wartmanni, Frolich and Zeder in Trutta trutta. Specimens in the museum at Vienna had been found in Salmo thymal- lus=Thymallus vulgaris. He further stated that Martin had found it in Salmo alpinus and in Trutta fario. This serves as a very excellent 113] PROTEOCEPHALIDAE—LA RUE 113 summary of the hosts which had been recorded for this species up to this time. Rudolphi (1819:495) stated that Bremser's specimens which had been taken in the pyloric caeca of Salmo thymallus belonged to Taenia longicollis and not to Bothriocephalus. He further stated that Taenia Renkina Schrank is identical with Taenia longicollis because 1"^ Salmo Wartmanni is called Renken in central Germany. Schrank 's (1803 :242) description of Taenia renkina is not at hand hence it is necessary to follow Rudolphi's judgment in the matter. Dujardin (1845:585) added but little to the data of the earlier authors. Diesing (1850:512-13) gave a literature review that is of value. Von Linstow (1878:262) in his catalogue of entozoa gave Salmo salvelinus as a host of this species. Zschokke (1884:11, 14-16) identified and described some cestodes from Coregonus fera and Salmo umhla, Lake Geneva, as Taenia longi- collis. A careful comparison of his descriptions of T. longicollis and T. ocellata, likewise reported by him from the same hosts, causes the writer to conclude that his specimens belonged to the same species. Length forms the chief difference between his species. In describing certain organs of the two forms he used almost identical phrases. Kraemer (1892) in his study of Taenia ocellata evidently used length as the chief distinguishing character. Zschokke 's description of T. longicollis does not agree with the description and figures of that form as given by von Linstow (1891:565-576). Von Linstow 's specimens were taken from Coregonus eperlanus, one of the hosts in which Rudolphi found T. lon- gicollis. It is therefore probable that von Linstow 's specimens rather than Zschokke 's belong to Rudolphi 's species. Moreover, von Linstow 's description agrees more completely with Rudolphi 's than does Zschok- ke 's. Lonnberg (1894:803) included Taenia longicollis Rud. in the list of species in his genus Ichthyotaenia. Zschokke (1896:772-777) listed Ichthyotaenia longicollis only in Trutta fario from Lake Geneva. Thanks to Prof. H. B. "Ward, the writer has been able to examine parts of a strobila of Zschokke 's **T. longicollis aus Forelle" (Trutta fario) and is able to state positively that it is not the same species as von Linstow 's T. longicollis. Nor is it the same as the specimens from Coregonus fera which Zschokke sent to Professor Ward as T. ocellata (No. 0.99 in Prof. H. B. Ward's collec- tion, the type of P. fallax La Rue). Von Ratz (1897:159) listed Ich- thyotaenia longicollis from Esox lucius from Lake Balaton in Hungary. This is probably a misdetermination. Von Ratz gave no description so not even a probable determination can be made. Miihling (1898:36) reported Ichthyotaenia longicollis Rud. from Coregonus alhula at Nico- laiken and from Osmerus eperlanus at Rositten in East Prussia. He 114 ILLINOIS BIOLOGICAL MONOGRAPHS [114 gave no description. Nufer (1905:75) in the report of an investigation of Lake Lucerne reported Proteocephalus longicollis from Perca fluvia- tilis, Alhurnus lucidus, Squalius cephalus, S. leuciscus, Esox lucius, Coregonus wartmanni nohilis, C. exiguus albellus, C. schinzii helveticus and Salmo salvelinus. It is extremely doubtful if the specimens of Pro- teocephalus which Nufer found in other than the salmonoid fishes be- long to the species P. longicollis. Nufer 's tabulated description of P. longicollis (Nufer 1905:147) is based almost entirely upon the work of von Linstow (1891). The character of Nufer 's work has been discussed at some length in connection with P. macrocephalus and P. torulosus. Many of the statements made in those places regarding his work apply here. A discussion of the facts brought out in this historical summary cannot yield very satisfactory conclusions. For the most part the au- thors cited have necessarily been compelled to depend upon the exter- nal features of the worm for diagnostic characters. Benedict (1900) showed how little dependence could be placed on such characters alone for descriptive purposes. The earlier workers necessarily based their conclusions on little else than external features, upon records of hosts, and locality of collection. The host records of all the workers who reported this species prior to Nufer and von Ratz show that these men regarded this species as being peculiar to the salmonoid fishes and it seems quite probable that they were correct in this respect. It is im- possible to determine whether this species is parasitic in all the salmon- oid fishes of the list or whether a number of cestode species have been reported under the one name without a painstaking comparative study of such specimens. as exist in private and museum collections together with a study of specimens from hosts and localities as indicated in the list of hosts. It is not likely that this will be done, at least not for some time. The question of priority of name is not an important one. This species is known as one of Eudolphi's species probably on account of the weight of Rudolphi's authority as much as on anything else. His first notes on this species contain only the briefest diagnosis and he dis- tinctly says, "Zeders Beschreibung ist vollkommen geniigend", etc, etc (vide supra). In the light of this it seems that Zeder should be cred- ited with the specific name longicollis. It is true of course that Rudolphi was the first to use the combination Taenia longicollis. As to the use of the name longicollis or some of the names that were proposed still earlier, viz.. Taenia Froelichii, T. salmonis wartmanni and T. eperlani, it may be said that the identity of the last is not well known. Ru- dolphi (1819) thought it was not identical with T. longicollis. T. ml- 115] PROTEOCEPHALIDAE—LA RUE 115 monis Wartmanni being a descriptive name of three parts is not avail- able. It is not necessary to discuss the question as to whether it was sufficiently described to give it any standing. T. Froelichii was evi- dently based on the same description as the T. salmonis Wartmanni for Gmelin (1790) gives little more than a catalogue of species and refers to Froelich's (1789) work. Since the combination Taenia longicollis Rudolphi is no longer the proper one with which to designate this species, the generic name Proteocephalus being used to designate the genus, it is here suggested that the proper combination for the designa- tion of the species is Proteocephalus longicollis (Zeder). In a recent article the writer, La Rue (1911:475), overlooked the priority of Ze- der 's Alyselminthus longicollis over Rudolphi 's Taenia longicollis and hence in a list of species of Proteocephalus gave the credit for the P. longicollis to Rudolphi instead of Zeder. The description is based on von Linstow's (1891) paper. His ma- terial was collected from Osmerus eperlanus which is one of the hosts in which Rudolphi found Taenia longicollis. Von Linstow reports that his largest specimen measured 46.4 mm. long by a maximum breadth of 0.99 mm. At its posterior end the worm measured 0.83 mm. broad. The scolex measured 0.43 mm. broad, the neck 0.3 mm. broad by 3.2 mm. long, first proglottids 0.43 mm. long by 0.71 mm. broad, proglottids at end of first third of strobila 0.53 mm. long by 0.99 mm. broad. The proglottids gradually increase in length until the last are 1.03 mm. long by 0.83 mm. broad. The end-proglottid is triangular and drawn out posteriorly. The specimen was incom- pletely developed. The four suckers have a circular outline, 0.12-0.14- 0.18-0.19 mm. in diameter. A fifth apical sucker has a diameter equal to one-half that of the others. The excretory system is made up of two large lateral vessels, one on either side just outside of the vitellaria, and six smaller vessels, three on either side lying dorsal to the larger vessel. All excretory vessels are greatly twisted and many anastomoses connect them. About 0.08 mm. anterior to the posterior margin of each proglottid a transverse commissure connects the ventral excretory vessels. The latter measure 0.019 in diameter and the smaller vessels about 0.0078 mm. In the region just posterior to the suckers there is a circular commissure of excretory vessels from which branches extend anteriorly into the head. All the main vessels discharge into a small vesicle at the posterior end of the end-proglottid. The genital pore is marginal, irregularly alternating, and situated near the end of the anterior one-fourth of the proglottid (Fig. 167). The testes are large, spheroidal, measuring up to 0.09 mm. in diameter. 116 ILLINOIS BIOLOGICAL MONOGRAPHS [116 Von Linstow states that there are about 25 testes in each segment, and that these are situated in two fields near the vitellaria. In a draw- ing of a transverse section, reproduced (Fig. 168), von Linstow figures the testes in two layers. This causes the writer to suspect that the number of testes (25) as stated by von Linstow is too small. In all the species of Proteocephalus studied by the writer the testes have been in one layer if the number of testes was small and never in two layers unless they numbered at least fifty. Frequently one sees proglottids containing more than fifty testes lying in a single layer. It should also be borne in mind that von Linstow figured ten testes in his cross-section of the proglottid. Ten out of twenty-five is too large a proportion of testes to appear in one thin section through proglottids of this size. One wonders what was left for the other sections of which there must have been quite a number. Since the proglottid which von Linstow delin- eates is ripe or at least contained eggs in the uterus it seems probable that he overlooked the testes of the median region where the eggs would be densely packed. In the transverse section to which reference has been made the region dorsal to the coils of vas deferens is free from testes, a condition which exists in all the other species of the genus whether the number of the testes be few or many. If von Linstow 's statement that the testes lie in two lateral fields be correct then this species is the only exception to the rule that the testes in this genus are irregularly scattered in the field between the lateral vitellaria. The considerations above presented cause one to doubt the accuracy of von Linstow 's statements regarding the number and position of the testes. The vas deferens forms a, thick mass of coils in the middle of the pro- glottid. This mass apparently does not extend over to the cirrus- pouch. In von Linstow 's figure the cirrus-pouch, which he describes as a spindle-shaped muscular organ with a breadth of 0.110 mm., ex- tends just a little within the vitellaria, or about V^-Ys across the pro- glottid. The cirrus (Fig. 169) in the 46.4 mm. specimen was visible at a point 13.8 mm. posterior to the head. It is short and club-shaped, 0.34 mm. long, and it extends 0.2 mm. beyond the proglottid 's margin. A comparison of cirrus-pouches in Von Linstow 's figures (repro- duced Figs. 167 and 169) shows some evident discrepancies. The cirrus- pouch in Figure 167 is set far within the tissues of the proglottid and it is connected with the exterior by a slender tube. Figure 169 shows by far the more typical condition and is to be considered as the normal for this species. The bilobed ovary lies in the posterior part of the proglottid. The lobes are club-shaped. The vitellaria lie in the lateral fields. They dis- charge the yolk-cells through the paired vitelline ducts which pass to 117] PROTEOCEPHALIDAE—LA RUE 117 the interovarial space where they unite to form a common duct that empties into the ootyp^. Thus far von Linstow is correct in his descrip- tion of the organs of the interovarial space. According to him the va- gina discharges into the ootype as do also the two lobes of the ovary. He provides no visible means for the escape of the fertilized eggs from the ootype. The writer agrees with Monticelli (1891:162) in thinking that von Linstow has probably mistaken the oocapt for the ootype, and has erroneously figured the vitelline ducts which pass near the oocapt and the shell-glands lying near as discharging into it. The barrel-like form of the ootype as he figures it (Fig. 167) is much more typical of the oocapt. The ootype has its long axis lying lengthwise of the oviduct and not perpendicular to it. The vagina in von Linstow 's figure is doubtless the oviduct. There is every reason to believe that the organs of the interovarial space bear the same relations to each other in this species as they do in the other members of the genus. The vagina opens into the common genital sinus always anterior to the cirrus-pouch. Without crossing the latter the vagina describes a curved course to the interovarial space where it forms several coils. Von Linstow did not mention the presence of a sphincter vaginae. The uterus has three large lateral pouches on either side. A uterine pore is lacking. The latter could perhaps be found after a careful examination. The unripe eggs measure 0.0156-0.0196 mm. in diameter. The plerocercoid of this species is found in the liver of the host in which the adult is found. It is evident from a study of Von Linstow 's figures and text that he made several misinterpretations of the structural plan of this cestode. He recognized that its plan differed in certain respects from the plan on which the Taenias are formed for he said that the Taenias of fish formed a distinct group in the genus Taenia. He apparently did not note the marked resemblance of their plan to the plan of the Tetra- phyllideans. Whether his failure to recognize the relationships of this species was the cause or the effect of his misinterpretation of its struc- ture cannot be determined. At any rate because of some doubtful points his material should be re-examined and a comparative study made if such be possible. This species is readily separated from the P. torulosus by its fifth sucker, and by its somewhat smaller head and smaller suckers. The ovarian lobes are more slender in this species than in P. torulosus. P. longicollis is readily differentiated from P. percae by its larger head, larger suckers, shorter cirrus-pouch, fewer (?) testes, fewer uterine pouches and by the position of the genital pore. P. longicollis resembles P. cernuae in a very few particulars such as shortness of cirrus-pouch. However, P. longicollis has a larger head, larger suckers, fewer uterine 118 ILLINOIS BIOLOGICAL MONOGRAPHS [lis pouches, smaller embryos, fewer and smaller testes which are differently arranged. P. longicoUis is much larger than P. fallax La Kue and P. dubius La Rue and it differs further in having fewer uterine pouches, a shorter cirrus-pouch, fewer ( ?) and larger testes. The genital pore is further anteriad in P. longicoUis than in P. fallax or P. dubius. P. longicoUis differs from P. dubius La Rue in having fewer uterine pouches, a shorter cirrus-pouch, fewer and larger testes and a different arrangement of the same. P. longicoUis does not closely resemble any species reported from North America up to the present time. PROTEOCEPHALUS TORULOSUS (Batsch) [Figs. 7, 78-80, 145, 146, 184] 1782 : Taenia articulis rotundis 1786: Taenia torulosa 1788: Taenia orbicularis 1791 : Taenia simplex 1790 : Taenia torulosa 1795 : Taenia cyprini idi 1800: Bhytelminthus cyprini 1802: Taenia torulosa 1803 : Halysis torulosa 1810: Taenia torulosa 1819: Taenia torulosa 1845: Taenia torulosa 1850: Taenia torulosa 1861 : Taenia porulosa 1884: Taenia torulosa 1889: Taenia torulosa 1891: Taenia torulosa 1892: Taenia torulosa 1894: Ichthyotaenia torulosa 1896 : Ichthyotaenia torulosa 1897 : Ichthyotaenia torulosa 1901 : Ichthyotaenia torulosa 1902: Ichthyotaenia torulosa 1905 : Ichthyotaenia torulosa 1905: Proteocephalus torulosus 1909: Ichthyotaenia torulosa 1911 : Proteocephalus torulosus Bloch 1782 :11 Batsch 1786 :181-182 Schrank 1788 :49 Frolich 1791 :58-61 Gmelin 1790 :3081 Viborg 1795 :240 Zeder 1800:215,220 Rudolphi 1802a :110-112 Zeder 1803 :352-353 Rudolphi 1810:111 Rudolphi 1819 :149-150 Dujardin 1845:584 Diesing 1850:514 Van Beneden 1861 :162-163 Zschokke 1884:20, in part Lonnberg 1889:15 von Linstow 1891 :565 Kramer 1892 :55 Lonnberg 1894 :801-803 Zschokke 1896 :775 von Ratz 1897 :159 Fric & Vavra 1901 :111-112 Schneider 1902 :24 Schneider 1905 :24-25 Nufer 1905 :75, 147, in ] Liihe 1909:32 La Rue 1911 :475 119] PROTEOCEPHALIDAE—LA RUE 119 Specific Diagnosis: Characters of the genus. Large cestodes 65- 600 mm. long by 1.2-2,25 mm. broad. Head large, prominent, swollen, flattened dorsoventrally, without rostellum, without fifth sucker. Breadth of head 0.480-0.600 mm., thickness about 0.300 mm. Suckers circular, prominent, with deep cavities, directed anteriad and outward. Diameter of sucker 0.18-0.20 mm. Neck thick, broad, 2-3 mm. long, wrinkled. First proglottids much broader than long, mature and ripe proglottids almost always broader than long. Maximum length of ripe proglottids 1.0 mm., maximum breadth of same 2.5 mm. Proglottids fleshy, well delimited by deep inter-segmental furrows, corners of seg- ments prominent. End-proglottid rounded posteriorly. In its posterior end a deep indentation. Genital pore irregularly alternating, situated near middle of lateral proglottid margin. Vaginal opening dorsal and anterior to opening of cirrus-pouch. Cirrus-pouch and vagina opening into a common genital sinus. Testes large, 0.16 by 0.08 mm., 100-110 in number. Testes in two layers, one occupying the whole dorsal field between vitellaria, completely covering ovary. Vas deferens, an eccentric mass of coils reaching from cirrus-pouch to middle of proglottid. Cirrus-pouch about 0.255 mm. long by 0.085 mm. broad, extending l^-% across pro- glottid breadth. Cirrus short, not heavy. Ductus ejaculatorius describ- ing few or no coils. Vaginal opening dorsal and anterior to cirrus-pouch. Sphincter vaginae very weak, situated near vaginal opening. Vagina not crossing cirrus-pouch. Vitellaria lateral, voluminous, follicles large and closely packed together. Ovary bilobed, lobes long, thick, and irregular in outline. Ootype and oocapt present. Uterus in ripe proglottids with 3-4 lateral pouches on either side. Uterine pores not observed. Eggs provided with three membranes. Outer membrane hyaline, 0.055 mm., second membrane granular, 0.032 mm., embryo about 0.021 mm. in diameter. 120 ILLINOIS BIOLOGICAL MONOGRAPHS Habitat : In intestine of host. [120 Host Locality Collector Authority Idus melanotus (Cyprinus jeses) (type host) Idus melanotus (Cyprinus Batsch (1786:181-182) jeses) Berlin Bloch Rudolphi (1819:150) Idus melanotus {Cyprinus jeses) Greifswald Rudolphi Rudolphi (1819:150) Idus melanotus (Cyprinus orfus) Leuciscus leuciscus Frolich Rudolphi (1819:150) Rudolphi (1819:150) Zeder Leuciscus leuciscus _„ von Linstow (1878:254) Leuciscus leuciscus Podiebrad, Fric and Fric & Vavra Bohemia Vavra (1901 :lii-ii2) Leuciscus leuciscus Lake Lucerne Xufer Nufer (1905:75) Idus melanotus (Leuciscus idus) Abildgaard Diesing (1850:559) Diesing (1850:514) Schneider (1902:24 Idus melanotus (Leuciscus idus) Idus melanotus (Leuciscus idus) (In M. C. V.) Finland Schneider & 1905:24-25) Leuciscus grislagine Sweden (?) Tullberg Lonnberg (1889:15) Albumus bipunctatus (In M. C. V.) Diesing Diesing (1850:514) Alburnus sp. Creplin Diesing (1850:514) Albumus lucidus von Linstow (1878:258) Alburnus lucidus Lake Geneva Zschokke Zschokke (1884:20) Alburnus lucidus Lake Lucerne Kraemer Kraemer (1892:55-71) Alburnus lucidus v^on Lin stow von Linstow (1891:565) Alburnus lucidus Zschokke Nufer Zschokke (1896:775) Alburnus lucidus Lake Lucerne Nufer (1905:75) Aspius rapax Creplin Diesing (1850:514) A bra mis brama von Linstow (1878:258) Abramis brama Lake Balaton von Ratz von Ratz (1897:159) Idus melanotus von Linstow (1878:255) Pelecus cultratus Lake Balaton von Ratz \on Ratz (1897:159) Gobio fluviatilis Lake Lucerne Xufer Nufer (1905:75) Squalius leuciscus Lake Lucerne Nufer Nufer (1905:75) Blicca bjoerkna Lake Lucerne Nufer Nufer (1905:75) ( ?)Coregonus fera Lake Geneva Zschokke Zschokke (1884:20) (?)Coregonus exiguus albellus Lake Lucerne Nufer Nufer (1905:75) (?)Coregonus schinsii helveiicus Lake Lucerne Nufer Nufer (1905:75) (?)Salmo salvelinus Lake Lucerne Nufer Nufer (1905:75) ( })Perca fluviatilis Luke Lucerne Nufer Nufer (1905:75) (?)Perca fluviatilis Podiebrad, Fric and Fric & Va\Ta Bohemia Vavra (1901 :iii-ii2) (?)Lota vulgaris Lake Geneva Zschokke Zschokke (1884:20) 121] PROTEOCEPHALIDAE—LA RUE 121 Batsch (1786:181-182) first described this species from Cyprinus jeses giving it tlie name Taenia torulosa. His description is here quoted in fuU: "Taenia torulosa. Der rundgliedrige Bandwurm. "Bloch Preissschr. S. ii nr. 4. T. 2. fig. 1-4. 10. 11. Taenia articulis rotundis. Der rundgliedrige Bandwurm. Taenia (loriformis) capite inermi, obtuso, osculis per paria difformibus: corpore toruloso, articulis orbicularibus coUo crenato, elongata. "Diese und die folgende Art haben einen abgestumpften, die nachsten fiinf aber einen stumpfspitsigen Scheitel, bei alien sind weder die Haken, noch der besondere Russel vorhanden wie bei denen vier vorigen. "Der rundgliedrige Bandwurm hat rundliche Glieder, die kurz, dick, und undurchsichtig, und wie eine Korallenschnur an einandergereiht sind. Am Rande die Miindungen. "Der Hals ist kurz. "Der Kopf bewegt seine vier Saugmiindungen paarweis, bald in halbmond- formige Wiilste, bald in die Gestalt eirunder Oeffnungen. Bisweilen erweitert er sie alle vier in eine zirklrunde Form, und alsdenn verschwindet ihr sonst sicht- barer Ring. "Die Eier gehen unter dem Presschieber haufig ab. "Die Lange betragt zwei Zoll, die Breite eine Linie. "Er findet sich im Aland (Cyprinus Jeses) nebst vielen Nelkenbindwiirmem und Kratzern." Batsch 's drawings of the head are reproduced (Figs. 145, 146). Prior to Batsch (1786) one other investigator reported cestodes of Cyprinidae which perhaps may be referred to this species. Bloch (1782:11) also had found this form in Cyprinus. He reported it under the descriptive name Taenia articulis rotundis. His report is inaccessi- ble to me. Batsch knew of Bloch 's report for he mentions it. Schrank (1788:49) reported this species under the name Taenia orbicularis and he mentioned Taenia articulis rotundis Bloch as a synonym. His diag- nosis reads: "Vier Saugmiindungen am Kopfe; die Glieder des Kor- pers tellerformig. Taenia orbicularis Wohnort, im Aland. ' ' Frolich (1791:58-61) described a cestode from Cyprinus orfus giving it the name Taenia simplex. This article is not accessible to me. Rudol- phi (1802a :110-112) commented on Frolich 's work on this form in these words: "Dass er (Frolich) Blochs Taenia torulosa nicht citirt, ist sehr begreiflich, da Bloch die Glieder ganz anders vorstellt. Ich glaube, dass die Taenia simplex nur jiingere Exemplare derselben Art bezeich- nen." Gmelin (1790:3081) gave a brief diagnosis of Taenia torulosa which he credited to Batsch (1786) tho he also made reference to Bloch (1782). His diagnosis reads: "T. elongata torulosa, capite obtuso, collo crenato, articulis orbicularis : osculis geminis difformis, Habitat 122 ILUNOIS BIOLOGICAL MONOGRAPHS [122 in Cyprino Jese, ad 2 pedes longa, capite piano, anierius truncato, coUo hrevi, articulis brevibtis crassis." Viboi^ (1795) reported Taenia cjrprini idi upon which Budolphi (1810:213) commented in these words: "Taenia Cyprini Idi. Viborg Ind. Mus. Vet. Hafn. p. 240. n. 133. T. Cyprini Idi. "Non describitar, forsan tamen ad Taeniam torulosam (n. 22) per- tinet, quae pluribus in Cyprinis occurrit." Viboi^'s writings are not accessible to me. Dr. C. W. Stiles in reply to a letter asking for information on this species wrote, "Appar- ently Viborg mentions Taenia idi in 1795a (See author's Catalogue),** referring to the Index Catalogue of Medical and Veterinary Zoology. Zeder (1800:215, 220) reported a cestode from Cyprinus under the name Rhyielminihus cyprini which name he later (1803:352-3) consid- ered to be a synonym of Halysis torulosa. His last diagnosis reads: "HA LYSIS TORULOSA.— fere linearis, plana; capite terete, antice truncato, cum coUo longo continuo; osculis anticis conicis; corpore cre- nato Habitat in intestinis cyprinorum jesis et leucisci." Rudolphi (1802a :110-12) after stating a brief diagnosis of Taenia torulosa presented some new data in the words which are here quoted: "Ich habe diesen Wurm, wie Bloch, im Dannkanal des Alands, Cyprinus Jeses, im April, ausserst haufig angetroflfen, aber nie iiber einen Fuss lang, da ihn Bloch hingegen doppelt so gross angetroffen hat. Der Kopf ist von Bloch gut beschrieben und abgebildet, die Saugwarzen und der ganz Kopf verandem ihre Gestalt alle Augenblicke, bald stehen ein paar Saugmiindiuigen stark hervor, bald nur eine, bald alle; bald erscheinen sie wie tiefe Napfschen, bald stehen sie hervor, bald sieht man sie zur Halfte, bald ist der Rand gleichsam doppelt u. s. w. Uebri- gens kann ich sie schon mit blossen Augen sehen; der Kopf ist bald mehr, bald weniger aufgeblasen, und immer starker als der Hals. Der Korper ist rundlich imd wird nach hinten allmalich grosser; dass er gegliedert ist, glaube ich gefunden zu haben, aber so deutlich ist er es nicht, wie man es auch nach der Blochschen Zeichnung (Taf. II. Fig. i.) glauben sollte, wo man in einiger Entfemung vom Kopfe schon grosse runde Glieder wahmimmt ; bei den vielen von mir unter- suchen Exemplaren nimmt der Korper in seinem Verlauf nur schwach zu, und die Glieder sind nur schwach unterschieden ; auch habe ich an keinem einzigen eine SeitenoflFnung bemerkt. Diese letztere findet man aber gewohnlich nur bei grossen Exemplaren, und will ich also darin geme Blochs Beobachtungen glauben." Rudolphi (1810:111) gave a diagnosis, synonymy and description of this species which, because it admirably sums up all the previous work on the form and because of its inaccessibility, is here quoted verbatim : "Taenia torulosa Batsch. — Taenia: capite truncato, osculis orbicularibus mar- ginatis, collo mediocri, articulis crassiusculis (subquadratis) subrotundis. Bloch Abb. p. II. Tab. 2. fig. 1-4. Taenia articulis rottmdis. 123] PROTEOCEPHALIDAE—LA RUE 123 Batsch Bandw. p. i8i n. 27. fig. 105-108. Taenia torubsa. Schrank Verz. p. 49. 11,150. T. orbicularis. Gmel. Syst. n. p. 3081. n. 85. T. torulosa. Frolich im Naturf. 25. p. 58-61. T. 3. fig. 4-6 T. simplex. Zeder Nachtrag p. 220. Rhytelminthus Cyprini. Rudolphi in Wied. Arch. iii. i. p. no. Taenia torulosa. Zeder Naturg. p. 352. n. 39. Halysis torulosa. "Hab. in ventriculo vel intestinis Cyprinorum. In Cyprino lese Bloch et ego Aprili, in Orfa Frolichius eodem, in Leticisco Zederus Majo mense, reperimus. "Descr. Vermes Zederiani septem ad novem lineas longi, dimidiam lati ; Frolichiani duos ad quinque pollices longi, postice lineam lati ; mei pedem non superantes vix lineam dimidiam lati ; Blochiani duos pedes longi, lineam et quod excurrit lati. "Caput truncatum, depressum, sub motu polymorphum, inflatum et osculorum directionem sum mopere mutans ; haec circularia, concava, marginata, margine simplici \el duplici, interdum occultato ; mox omnia quatuor, mox duo tantum in conspectum veniunt, ceterum oculis nudis usurpanda. Collum depressum, medio- cre, a capite crassiore discretum. Corpus crassiusculum, subaequale, margine cre- natum, articulis confluentibus, margine postico vix incumbentibus. "Obs. I. Blochius specimina sex maxima vidit, eorumque articulos quam in meis magis discretos, ovis farctos, et foramina marginalia (haec tamen non ulte- rius exposita, neque delineata) observavit. Frolichiani vermes a meis vix ulla nota differunt, nisi quod collum longum dicat, quod ipse mediocre, Blochius breve vocaverit, hoc autem vermis totius ratione habita facile explicatur ; in vermlbus enim bipedulibus collum vix pollicare Blochio breve visum, quod Frolichio in bivel quinquepollicaribus longum, mihi in pedalibus mediocre fuerit. "Obs. 2. Zederiani vermes valde pusilli fuere, ideoque a nostria megis dis- tant; ab osculis quatuor suctoriis totidem canales oriebantur, in corpore progressi, tandem in unicum vas abeuntes, quod in cauda obtuso-acuta terminabatur. Haec vasa mihi non visa, sed vermes illi tenelli plani, ideoque pellucidi fuere, nostri muto crassiores, fere teretiusculi. Zederus etiam postea ipse Rhytelminthum cy- prini olim sibi dictum ad T. torulosum pertinere suspicatus est, quod olim in diario Wiedemanniano aeque indicaveram. Conf. etiam Taeniam Cyprini Idi n. 114. dictam." Rudolphi (1819:150) stated that this species had been found by Bloch, Frolich, Zeder and himself in certain species of the Cyprinidae. Dujardin (1845:584) made no record of finding this species. He col- lected his data from descriptions by Zeder, Frolich, and Bloch, His description reads: '* — Long de 16 a 20 mm, et large de 1,12 mm. (Zeder), ou large de 50 a 135 mm, et large de 225 mm (Froelich), ou long de 330 mm, large de 1.2 mm, (Rud.), ou enfin long de 660 mm, large de 225 a (?) (Bloch) ; — tete tronquee, de forme tres- variable, ainsi que ses ventouses dont le bord est saillant; — trompe nuUe; — cou de longueur mediocre ; — articles assez epais, presque ronds. ' ' 124 ILLINOIS BIOLOGICAL MONOGRAPHS [124 Diesing (1850:514) found this species in Leuciscus idus and in Alhurnus bipunctatus and further stated that Creplin found it in As- pius rapax and in Alburnus sp. Diesing 's diagnosis added a little to the previous knowledge of the form. His diagnosis reads: ^^ Caput latum depressum truncatum, acetabulis lateralibus limbo prominulo. Collum longum. Articuli teretiusculi subaequales longi confluentes. Aperturae genitalium. . . Longit. 7-10"; latit. i/^-l'"." Van Bene- den (1861:162-163) reported finding this form in several species of Cyprinidae ("plusieurs especes de cyprins"). Altho he gave almost no descriptive data a comparison of his figures with those of Batsch leaves little doubt that his Taenia porulosa is identical and synonymous with T. torulosa Batsch. Porulosa probably is a misspelling of torulosa. Some authors have denied the synonymy of these names but their con- tention has no support of facts. Van Beneden failed to state the locality of his catch. Von Linstow (1878 and 1889) catalogued the hosts from which this species had been collected. He added nothing to the descrip- tion of the species. Zschokke (1884:20) stated that he found Taenia torulosa in Core- gonus fera, Lota vulgaris and Alhurnus lucidus from Lake Geneva. Since Zschokke reported Taenia longicollis and T. ocellata from Core- gonus fera in addition to Taenia torulosa it is highly probable that all of his specimens from Coregonus belonged to one of the last named ces- tode species rather than to T. torulosa. Zschokke further states that his specimens were too young to permit him to recognize any trace of the internal organs. These statements as to a probable misdetermina- tion of species apply equally well to his parasite report on Lota vulgaris in which case he found Taenia ocellata in addition to Taenia torulosa. His four young specimens from Alhurnus lucidus may have been Taenia torulosa if only the question of host be considered. Of these four speci- mens he wrote: '*La tete etait large, tronquee, les ventouses tres fortes et saillantes. Le cou etait de longeur, mediocre, la segmentation en articles peu accusee." Lonnberg (1889:15) reported the finding of Taenia torulosa by Professor Tullberg. He gave no description and did not state the locality of the collection. Von Linstow (1891:565) found Taenia torulosa in Alhurnus lucidus. He gave no data. Kramer (1892:55) found Taenia torulosa in Alhurnus lucidus, Lake Lucerne. He examined more than 150 specimens of Coregonus fera without finding a single specimen of Taenia torulosa, and among numerous specimens of Alhurnus lucidus but a single host was infected with Taenia torulosa. He made the first careful morphological and histological study of this species. Lonnberg (1894:801-803) included Taenia torulosa in a list of species of his new genus Ichthyotaenia. 125] PROTEOCEPHALIDAE—LA RUE 125 Zschokke (1896:775) found Ichthyotaenia torulosa (Batsch) in the in- testine of Leuciscus leuciscus L. He found it in no other hosts. Von Ratz (1897:159) reported finding Ichthyotaenia torulosa in Abramis hrama L. and in Pelecus cultratus L. in Lake Balaton, Hungary, but he gave no description. Fric and Vavra (1901:111-112) reported what they considered to be Ichthyotaenia torrulosa (Batsch) (misspelling for torulosa) from Leuciscus leuciscus and Perca fluviatUis, Podiebrad, Bohemia. The description of their specimens agrees very well with that of Proteocephalus percae and a part or all of their specimens may belong to that species. The Hasling (Leuciscus leuciscus) would be a new host for P. percae and it may be that their specimens from that host are as they identified them, i. e., P. torulosus. Moreover, it is not impossible that Fric and Vavra failed to distinguish between the two species of cestode, P. percae and P. torulosus. It is impossible to make a complete determination from their data. Schneider (1902:24) found Ichthyotaenia torulosa in Leuciscus idus in Finland. Three years later he (1905:24-25) briefly but concisely described this species from Leu- ciscus idus. His description agrees very well with that of Kramer (1892). Nufer (1905:75) reported Proteocephalus torulosus (Batsch) from Perca fluviatilis, Alburnus lucidus, Squalius leuciscus, Blicca hjoerkna, Oohio fluviatilis, Coregonus exiguus aVhellus, C. schinzii helveticus, Salmo salvelinus. Some of Nufer 's report is open to doubt. In 59 specimens of Perca fluviatilis he not only failed to find the species which Zschokke found in that host but he found P. longicollis and P. torulo- sus, a species which only once before (Fric and Vavra, 1901) had been reported from that host. In that instance attention has been called to the fact that the specimens in question were probably P. percae and not P. torulosus. Nufer 's P. torulosus and his P. longicollis may have been P. percae. Nufer 's next four hosts after Perca fluviatilis are all Cy- prinidae, from which group this species has heretofore been reported. It is extremely doubtful if the Salmonidae harbor this species. Zschok- ke, who in 1884 reported young specimens of Taenia torulosa from Coregonus fera, in 1896 found this parasite only in Alhurnus lucidus. Zschokke 's paper (1896) contained the results of his investigations on more than 1600 fish from Lake Geneva and the Rhine hence his data were fairly comprehensive. Moreover, from the three species of Salmon- idae in which he claimed to have found P. torulosus Nufer reported two other species of Proteocephalus, namely, P. longicollis and P. ocel- latus. Here again Nufer probably made a misdetermination. The writer has shown that Nufer 's work (see discussion of P. macrocepha- lus) is untrustworthy and in the determination of this species there 126 ILLINOIS BIOLOGICAL MONOGRAPHS [126 seems to be no exception. That Nufer made a misdetermination of his P. longicollis is not at all improbable since specimens labelled ^'Taenia longicollis aus Forelle" which have been received by Professor Ward from Professor Zschokke have proved to belong to a different species. Nufer 's tabulated description of P. longicollis (Nufer 1905:147) does not agree in some important points with von Linstow's description yet it is very manifest that he drew on von Linstow's description for a large part of his data. Likewise parts of Nufer 's description of P. torulosus (Nufer 1905:147) fail to agree with the descriptions of that species by Schneider and Kraemer. Liihe (1909:32) gave a short spe- cific description of this form under the name of Ichthyotaenia torulosa (Batsch). La Rue (1911:475) listed this form among other species of Proteocephalus. The following study is based upon some of Schneider's specimens which Prof. H. B. Ward secured from Professor Levander at Helsing- fors. This material is labelled ^^Ichthyotaenia torulosa Batsch. Leucis- cus idus. Porkala. Juni 1901. det. G. Schneider." It now bears the number 10.121 in Professor Ward's collection. From this material frontal and transverse sections have been made and some heads have been studied in glycerine. A careful comparison of Schneider's (1905) and Kraemer 's (1892) descriptions shows very good agreement. Zschok- ke 's (1884) description in parts agrees pretty well with these two. Liihe (1909) seems to have based his specific description largely on the work of Zschokke, Kramer, and Schneider. Data from these sources are used in this description. This is one of the larger species of Proteocephalus infesting fish. In length it varies from 65 to 600 mm. Specimens of the latter length are rare and have been reported only by some of the earlier investigators. The longest complete strobila examined by the writer was 110 mm. long. The breadth of the strobila varies from 1.2-2.25 mm. The head (Fig. 7) is large and very prominent, somewhat swollen in appearance, flattened dorso-ventrally, and somewhat flattened at the apex. Schneider found it 0.500 mm. broad. The heads in the writer's material measured 0.450- 0.600 mm. broad by about 0.320 mm. thick. The suckers are very prom- inent, nearly circular in outline, with deep cavities and strong muscu- lature. They are directed anteriad and a little outward. The suckers are 0.200 mm. in diameter according to Schneider and about 0.180-0.200 mm. in the heads examined by me. A fifth sucker is not present. In sections of the head the writer was unable to find even a trace of a vestigial fifth sucker. Nufer (1905:147) stated that the head of a 37 mm. specimen measured 0.255 mm. broad and the suckers of the same were 0.10 mm. in diameter. Nufer 's measurements of the head do not 127] PROTEOCEPHALIDAE—LA RUE 127 agree at all with the measurements made by Schneider or the writer. Neither Kramer nor Zsehokke give measurements of the head and suck- ers but they state that the head is large, the suckers large and round. Nufer's specimens which infested Perca fluviatilis most certainly could not have been P. torulosus (Batsch) but were either P. percae, P. fallax La Rue, or an undescribed species. Batsch drew the head of P. torulosus as a broad structure with large and prominent suckers. His figures which have been reproduced (Figs. 145, 146) should be compared with the drawing of a head (Fig. 7) derived from material sent to Professor Ward by Professor' Levander. There is remarkable agreement in form of head and of suckers. The thick neck is about 2-3 mm. long by about 0.20-0.30 mm. broad. It is much wrinkled thus making difficult the determination of the length. It passes over gradually into the first proglottids which are much broader than long. Mature and ripe proglottids are almost always broader than long. The maximum length observed was 1.0 mm. and the maximum breadth 2.5 mm. Many nearly ripe proglottids measure about 0.29 mm. long by 1.30 mm. broad. The proglottids are thick and fleshy with well defined limits. Indentations between the proglottids are deep and the corners of the latter are quite pronounced. The end proglottid is rounded posteriorly. At its posterior end it has a deep indentation into which the excretory ducts discharge. According to Kramer the excretory ducts in the head and neck region are very prominent with many anastomosing coils. In the neck region he found many branches of the excretory vessels leading to the exterior. Sections made by the writer failed to show these relations. The genital openings are irregularly alternating, and are situated near the middle of the margin of the segment. The vagina opens not strictly anterior to the cirrus-pouch but somewhat dorsal thereto. Kra- mer incorrectly states that the vagina and cirrus-pouch open near each other but not into a common atrium. The testes are large, spheroidal or by pressure they may be sometimes rendered polyhedral. They measure according to Schneider about 0.160 mm. in sagittal by 0.080 mm. in frontal diameter. My measurements are about the same as these. The testes lie in two layers, the dorsal layer (Fig. 78) covering the entire area bounded by the vitellaria and the anterior and pos- terior margins of the proglottid. Thus the ovary is completely covered by the dorsal layer of testes about 70 in number. In the more ventral layer there are about 30-40 testes. Hence the total number of testes is about 100-110. Kramer's drawing (Fig. 184) shows a small number of testes but since it shows the ventral view of the worm it cannot show a large number. The coils of the vas deferens form a thick mass ex- 128 ILLINOIS BIOLOGICAL MONOGRAPHS [128 tending from the cirrus-pouch to the mid-field of the segment. Kramer (Fig. 184) figures the coils of vas deferens lying in the middle of the segment. The cirrus-pouch is short and relatively thick. Its length is about 0.255 mm. and its breadth 0.085 mm. The ratio of its length to the proglottid breadth is about 1 A according to G. Schneider, 1 :3 in Kraemer's drawing, and 1:4-1:6 in my preparations. The cirrus is short and not very thick. Kraemer's description of the cirrus is faulty in that he said that the cirrus was armed with recurved hooks which extend back into the tissue of the cirrus itself. There are no hooks. The protruded cirrus has not been seen by the writer. The ductus ejaculatorius forms but a very few coils or instead of coils it may lie in sinuous curves within the cirrus-pouch. The vagina which opens mostly dorsal to the cirrus-pouch has a very weak sphincter muscle situated near the opening into the atrium. This sphincter vaginae is made up of a few strands of circular muscle fibers which may be easily overlooked. In its course to the interovarial space the vagina does not cross the cirrus-pouch but passes dorsal and anterior to the pouch. A small receptaculum seminis is present just anterior to the ovary. The vitellaria are lateral, voluminous, and fol- licular. The follicles are large and closely packed together. The bi- lobed ovary is large, weU developed, thick and irregular in outline, but the lobes are not as slender as they are shown in Kraemer's figure (compare Figs. 79 and 184). In proglottids 1.3 mm. broad the ovary may have a span of 0.80 mm. and the lobes may be 0.130-0.140 mm. thick. A muscular oocapt and an ootype are present. The uterus in ripe proglottids has 3-4 lateral out-pocketings on either side. The ute- rine pores have not been observed. The eggs were not described by Kramer and Schneider. The outer membrane is thin and hyaline, 0.055 mm. in diameter. The granular second membrane has a diameter of about 0.032 mm. and the embryo about 0.021 mm. A delicate mem- brane closely invests the embryo. P. torulosus differs from many other species of the genus by its large size, and from a large number of the species through its lack of a fifth sucker. In maximum length and breadth of its strobila it is the largest species of Proteocephalus yet described. In the width of the head and diameter of the suckers it is exceeded only by P. amhloplitis and P. perplfixus. In observed length P. torulosus greatly exceeds these species — and it may be differentiated from them by its lesser number of uterine pouches, its weaker sphincter vaginae, its shorter cirrus- pouch, its double layer of testes, and by the arrangement of the dorsal layer of the same. It is greatly different from the other North Ameri- can forms thus far described. Among the European forms P. torulosus 129] PROTEOCEPHALIDAE—LA RUE 129 is approached in size only by P. longicollis. The latter, however, has a well developed fifth sucker and, according to von Linstow, a much smaller number of testes. P. torulosus may be differentiated from P. percae and P. cernuae by its larger head, larger suckers, lack of a fifth sucker, more numerous testes and the different arrangement of the same, and by its smaller number of uterine pouches. P. torulosus is much larger than P. macroccphalus. It hds a larger head, larger suckers, fewer uterine pouches and a different arrangement of the dorsal layer of testes than the latter species. P. torulosus is so different from the other described species of Proteocephalus that a danger of its being confused with them is scarcely possible. 'i PROTEOCEPHALUS MACROCEPHALUS (Creplin) [Figs. 1, 47-49, 171] 1825: Taenia macrocephala Creplin 1825 1845: Taenia macrocephala Dujardin 1845:585 1850: Taenia macrocephala Diesing 1850 :513-514 1859: Taenia macrocephala Molin 1859 :13 1875: Taenia macrocephala von Linstow 1875 1889: Taenia dilatata Linton 1889 :488-489 1893: Taenia macrocephala Olsson 1893 1896: Ichthyotaenia macrocephala Riggenbach 1896 :267 1897: Taenia dilatata Linton 1897:425 1897: Taenia macrocephala Stossich 1897 :7 1898: Taenia macrocephala Stossich 1898a :113-114 1898: Taenia macrocephala Miihling 1898 :37, 69 1901: Taenia dilatata Linton 1901 :435 1903: Ichthyotaenia hemisphaerica Schneider 1903 :29 1905: Ichthyotaenia macrocephala Schneidei 1905 :10, 17-19 1905: Proteocephalus macroccphalus Nufer 1905 :134-152 1909: Ichthyotaenia macrocephala Liihe 1909:33-34 1911: Proteocephalus macroccphalus La Rue 1911 .475 Specific Diagnosis: The characters of the genus. Adult cestodes possessing strobila as much as 40 cm. long by 1-1.8 mm. broad or per- haps more. Segmentation quite distinct. Proglottids very numerous; first much broader than long; mature, broader than long or nearly quadrate ; ripe, longer than broad. Neck 5.0-7.0 mm. long, 0.1-0.25 mm. broad. Head globose, flattened dorsoventrally, 0.28-0.30-0.32 mm. broad, 0.15-0.16 mm. thick. Suckers 0.095-0.106 mm. in diameter. Fifth 130 ILLINOIS BIOLOGICAL MONOGRAPHS [130 sucker vestigial and deeply set in the tissue of the head, 0.025 mm. in diameter. Sexual organs as in genus. Genital aperture marginal, near middle of proglottid. Vagina anterior and vaginal opening dorsal to cirrus-pouch. Testes 100-120, irregularly scattered between vitellaria, lying in one or two layers, usually one. Cirrus-pouch short, about 0.16 mm. long. Ratio of length of cirrus-pouch to proglottid breadth 1:6- 1:8. Uterine pouches 7-11-12-14 on either side. Embryos 0.017-0.019- 0.021 mm. in diameter. Habitat: In intestine of Anguilla vulgaris (type host), and A. chrysypa Raf. Host Locality Collector Anguilla vulgaris Greifswald (type locality) Creplin u « Rennes Dujardin « <( Padua Molin « « von Linstow « <( << « Narenta Stossich « « Trieste Stossich « « Memel, E. Prussia Miihling « « Finland Schneider, G. « « Lake Lucerne Nufer " chrysypa Raf. Wood's Hole, Mass. Linton « « (( « , « Linton « « Sebago Lake, Me, H. B. Ward Authority Creplin (1825:69-71) Dujardin (1845:585) Molin (1859:13) von Linstow (1875) Olsson (1893) Stossich (1897:7) Stossich (18983:113-114) Muhling (1898:37-69) Schneider, G. (1903:29) Nufer (1905:134-152) Linton (1889:488-489) Linton (1897:425-426) LaRue (the present paper) Creplin (1825) found this species in the intestine of Anguilla vul- garis at Greifswald. His diagnosis and description are here given: "Taenia macrocephala: T. capite elongato, antice crassiore, osculis globosis anticis, rostello brevissimo obtuso, collo brevi, articulis anterioribus brevibus ob- tusis, sequentibus subquadratis, horum lemniscis marginalibus vage alternis. Hab. In intest. Maraenae Anguillae Martio, April, Majo et Junio banc Taeniam reperi aut singulum aut minima tamen copia. Descr. Vermes aliquot lineas usque ad octo poUices longi, majores medio corpore lineam cum quarta vel dimidia ejus parte lati, subdiaphani, albissimi. Caput oblongum, antice latius, rostello brevissimo, obtuso instructum, inerme, et quatuor osculis (quorum orificia non vidi) globosis, prominentibus, anticis, instructum. Collum breve, rugosum, cum capite continuum. Articuli antici bre- vissimi, inaequales, obtusi, passim medio constricti, sequentes sensim latitudine et longitudine crescunt, maximam partem quidem latiores, quam longi manent, de- 131] PROTEOCEPHALIDAE—LA RUE 131 mum vero quadrat! et ultimi adeo paulo longiores, quam lati evadunt. Omnes per articulos decurrit ad margines laterales utrinque linea alba opaca. Foramina articulorum posticorum marginalia vage alterna, ex quibus cirrhus propendet bre- vis, subtilissimus. Obs. I. Reperi primo hujus vermis specimen unicum valde parvum d. 2y Mart. 1822, postea d. 23. Apr. ej. anni iterum parva specimina una cum Bothrio- cephalis clavaecipitibus itidem parvis demum vero specimen octopoUicare d. 23. Maji 1822, et secundum specimen magnum d. 5. Junii 1823, simul cum illi adjacente Bothr. clavaecipite mediocre. Vi\X)s examinae microscopii ope non mihi licuit, ut majorem descriptionis partem de verme in spiritu servato dare debuerim. Obs. 2. Specimen Junio inventum vivacissimum, aquae frigidae immissum, valdopere se movebat et contorquebat, bisque motibus maximam ovorum copiam demittebat subglobosorum, ut tota aqua inde turbida fieret. Obs. 3. Hujus vermis caput sine dubio O. F. Miiller (Vid. Schriften Berl. Naturf. I. p. 208. cit. in Rudolph. Entozoologiae T. II. P. 2. p. 39.) vidit, cum Bothriocephalo clavaecipiti (Taeniae Anguillae sibi dicto, a nostra taenia omnibus notis diversissimo) caput osculis quattuor instructum adscriberet." Dujardin (1845:585) reported and described specimens of this spe- cies in these words: "Tenia de I'anguille. Taenia macrocephala. — Long de 8 a 220 mm, large de (?) a -Ti-Zy mm; — tete allongee, plus epaisse en avant, avec une trompe tres-courte, obtuse ; — ventouses globuleuses, dirigees en avant ; — cou court ; — premiers articles courts, obtus, les suivant presque carres, avec les orifices genitaux irreguliere- ment alternes, et les penis courts, tres-minces, pendants. "M. Creplin la trouve plusieurs fois, a Greifswald, dans I'intestin de I'an- guille. — J'ai trouve aussi a Rennes, dans une anguille, trois jeunes tenias longs de 6 mm et 10 mm et 13.5 mm, larges de 0.25 mm a 0.3 mm; ayant la tete large de 0.33 mm a 048 mm, sans trompe, et les ventouses larges de 0.106, dirigees en avant," Diesing (1850:513-514) added nothing to the earlier descriptions. Molin (1859) reported a specimen of this species taken from AnguUla vulgaris at Padua in March, 1859. He did not describe it. Von Lin- stow (1875) very insufficiently described P. macrocephalus from A71- guilla vulgaris in the following words (The quotation is taken from Nufer 1905 :135) : "Der Skolex ist gegen den folgenden Korper nicht abgesetzt; die vier grossen Saugnapfe haben einen Durchmesser von 0.166 mm.; dazwischen steht ein viel kleinerer, funfter, scheitelstandiger, von 0.026 mm. Durchmesser, der oft schwer aufzufinden ist. Die Cirren sind 0.2 mm. lang und 0.06 mm. breit ; am ausseren Drittel zeigen sie eine Einschniirung, sodass ungefahr die Gestalt der Kegel ent- steht, wie sie beim Kegelschieben iiblich sind ; sie ragen nur wenig mit der Spitze iiber den Rand des Gliedes hinaus und stehen unregelmassig abwechselnd. 132 ILLINOIS BIOLOGICAL MONOGRAPHS [132 Die aussere EihuUe ist hyalin und umgibt das Ei weitlaufig, denn sie hat einen Durchmesser von 0.089 mm., wahrend der der innern Eihiille nur 0.029 mm- und der der Eizelle selber 0.023 mm. betragt. Die Embryonalhakchen sind sehr fein; sie haben eine Lange von 0.006 mm." Von Linstow's measurements of the suckers much exceed those given by Schneider and the writer for this species. He also reported a small fifth sucker that was very difficult to see. The writer is inclined to the belief that this was the small vestigial fifth sucker which in some Pro- teocephalids may be seen in favorable toto preparations. Linton (1889:488-489) described some cestodes from Anguilla chrysypa Raf., caught on our eastern coast as a new species, Taenia dilatata in these words: "Head small, truncate, or, in living specimens, slightly prominent in front Acetabula nearly circular, directed a little forward. Neck rugose, very long, very contractile and dilatable, narrow in front, tapering toward the head ; a short distance back of the head expanding into a number of irregular, transparent, dilated folds, which border both sides of an opaque central portion, in which two longitudinal canals are faintly outlined. First segments about three times as broad as long; median segments square, or broader than long; ultimate segments nearly square, sometimes broader than long, sometimes longer than broad. Geni- tal apertures marginal, opening a very little in front of the middle. "A single specimen of this species of Taenia was obtained from the intestine of the Common Eel {Anguilla vulgaris) August 26, 1885. The length of the specimen, when stretched out by fastening one end with a needle to the bottom of the dissecting dish and removing all kinks and curves with a fine brush, was 170 mm. The length of the same specimen, after having been preserved in alco- hol, is less than 90 mm. The specimen when first obtained and placed in sea-water was quite active. The body was constantly throwing itself into sinuous curves, while the head and neck were jerked from side to side with a moderately rapid motion. In addition to these movements the neck and anterior portions of the body constantly changed their shape by the inflation or dilatation of the investing membranes into wide transparent folds, constricted at irregular int-ervals by nar- row transverse bands. The neck, meanwhile, was alternately stretched out and contracted like the body of a Nemertean. The anterior end of the head pro- truded into a proboscis like papilla. The breadth of the head itself varied from 0.17 to 0.35 mm. "In the alcoholic specimen the dilatable folds of the neck are much con- tracted and broken. They lie in rough, ragged frills along each side of the dark central part of the strobile. The head is truncate or blunt in front. The neck immediately behind the sucking-disks is almost as wide as the head, flat, thin, and little, if at all, tapeving. "The following measurements were made on the living specimen. The 133] PROTEOCEPHALIDAE—LA RUE 133 head and neck changed their position and shape so rapidly that it was with the greatest difficulty that trustworthy measurements could be made: Millimeters. "Breadth of head 0.28 Diameter of acetabula 0.12 Diameter of neck, narrowest part 0.20 Distance of first segments from head 17.00 Length of fourth segment from end of strobile 1.30 Breadth of same, posterior end 1.50 Breadth of same, anterior end 1.60 Length of posterior segment 0.90 Breadth of same, posterior end 0.60 Breadth of same, anterior end 1.25 "Habitat. — Common Eel (Anguilla vulgaris) ; intestine ; Wood's Hole, Mass., August 26, 1885; one specimen." "Von Linstow (Compend. der Helminth., 1878) records but two Taenia from the Common Eel, T. macrocephala Creplin and T. hemispherica Molin. T. dilatata is very different from the former. Diesing (Revis. der Ceph., Ab. Cycl., p. 378) mentions the latter, but gives no enumeration of characters. I do not have access to Molin's paper, and cannot, therefore say whether T. dilatata is identical with his species or not. The peculiar inflated character of the neck suggests T. ambigua Dujardin, but the difference in size between the adult specimens is alone sufficient to render the union in the same species impossible." Again Linton (1897:425) reported this species from A. chrysypa thus: "Taenia dilatata Linton. — No. 4812 U. S. N. M. From common eel (An- guilla chrysypa). Several strobiles but in bad state of preservation, no scolices; anterior ends have been exceedingly long and slender. The characteristic dilata- tions of this species can not be proved from these specimens. The general ap- pearance of the strobiles, as well as the character of the segments, however, agrees with this species. "It may be added that the segments of these specimens agree with Molin's description of his T. hemispherica. With the evidence at hand, however, the writer does not feel justified in uniting the two species of T. dilatata and T. hemispherica." Professor H. B. Ward secured this material, No. 4812, U. S. N. M. for my examination but its state of preservation was too poor to permit any positive determination being made, Linton (1901:435) recording the parasites of Anguilla chrysypa reported this species again. '^Taenia dilatata Linton. Specimens of this genus also taken in 1899, three on August 2. Dimensions in milli- 134 ILLINOIS BIOLOGICAL MONOGRAPHS [134 meters: Length, 8, diameter of head, 0.28. Diameter of sucker, 0.08. Segments not mature. One specimen August 28 ; length 14 mm. ' ' It is the writer's opinion that the folds of the neck are of no real diagnostic value. Such folds may be seen on many other specimens of cestodes in certain states of expansion and contraction. Unfortunately Linton failed to figure or describe any of those internal structures which are of real service to the modern systematist. His drawing of the ma- ture proglottid is such that it cannot be interpreted but his drawings of the head and of the last proglottids are of value for comparative pur- poses. Linton himself believed that the segments of his species agreed with Molin's description of T. hemisphaerica. Riggenbach (1896) con- sidered Linton's T. dilatata to be identical specifically with T. hemis- phaerica Molin. Nufer (1905) sought to show that these two species were identical with Proteocephalus macrocephalus (Creplin). This may prove to be the case but since the writer has not been able to study any material of the T. hemisphaerica he has preferred to consider the latter as a separate species. He is, however, ready to state that Linton's Tae- nia dilatata is specifically identical with Proteocephalus macrocephalus (Creplin). T. dilatata is therefore a synonym of the last named species and it should be dropped from the list of valid names for Proteocepha- lus species. Professor H. B. Ward very kindly secured for study Lin- ton's slides and some alcoholic material of his Taenia dilatata. These specimens, judging from the statements in his letter to Professor Ward, must be from the lots described by Linton in 1889 and in 1901. Meas- urements of the heads, suckers, proglottids and the cirrus-pouch, to- gether with the general appearance of the worms, give ample reason for considering this form to be identical with specimens taken from An- guilla chrysypa, Lake Sebago, Maine, and which the writer is describing as P. macrocephalus. These specimens agree in minute details of struc- ture with the cestodes which Schneider (1905) described as P. macro- cephalus. A more extended discussion of this comparison will be made in the proper connection (Vide infra). Olsson (1893) reported specimens of cestodes from Anguilla vulga- ris in Scandinavia. Riggenbach (1896) considered the form to be a species of Ichthyotaenia. Stossich (1897:7) reported this species from Anguilla vulgaris at Narenta, and again in a later paper (1898a :113-114) he gave a short diagnosis of specimens taken from the same host species at Trieste. In this diagnosis nothing of the inner anatomy of the worm is given. His diagnosis reads : "Lunghezza 220 mm. ; larghezza 3.5 mm. Scolice in continuazione del collo, allungato, ingressato al'innanzi, con grandi ventose globose, situate anteriormente ; rostello cortissimo, ottuso, provveduto di una piccola ventosa apicale. Collo corto. 135] PROTEOCEPHALIDAE—LA RUE 135 Proglottidi prime corte e ottuse, le seguenti subquadrate. Aperture genitali irrego- larmente alterne ; pene corto, sottilissimo, pendente, con una strozzatura verso I'apice. Uova con due invogli, lunghe 0.089 vam. Rara nell' intestino dell' An- guilla vulgaris (Trieste)." Stossich was evidently describing P. macrocephalus and not the P. hemisphaericus (Molin). Miihling (1898:37, 69) noted this parasite in A. vulgaris in East Prussia but gave no description. Schneider (1903: 29) reported from an eel a single specimen of what he then identified as Ichthyotaenia hemisphaerica. Later in a footnote (1905:10) he says of these specimens "Ichthyotaenia hemisphaerica kommt, wie es scheint, in den Aalen des Finnischen Meerbusens garnicht vor. Das Exemplar welches ich friiher einmal irrtiimlich als /. hemisphaerica bestimmt habe (Beitrage zur Kenntnis der Helminthenfauna des Finnischen Meerbu- sens. Acta Soc. pro Fauna et Flora Fennica 26, No. 3. 1903. S. 29), erwies sich bei genauerer Unterschung auch als Ichthyotaenia macro- cephala. ' ' From this statement the writer infers that Schneider at that time considered P. hemisphaericus to be a distinct species. In the text of the same article Schneider (1905:17-19) described P. macrocephalus, re- cording for the first time in the history of the species a careful study of its inner anatomy. For this reason a condensed resume of his de- scription is here given. Proteocephalus macrocephalus: This species is a close relative of P. percae and is differentiated therefrom by the very short cirrus-pouch and the short cirrus. The scolex has a diameter of about 0.30 mm. The diameter of the large deep suckers is 0.100 mm. The fifth sucker as in P. percae is a rudimentary structure made up of long cells and having a diameter of 0.025 mm. (The writer has shown that this organ in P. percae is a true sucker.) The neck is quite broad and is strongly compressed dorsoventrally. The body attains a length 40 cm. and more. A specimen 11 cm. long and 1.8 mm. broad had about 200 segments. The youngest proglottids are about five times as broad as long. The middle mature proglottids are broader than long while ripe proglottids are longer than broad. The ovaries appear from the surface as two small stripes, as they do in P. percae. In old ripe proglottids they are of irregular shape, bent and somewhat overlapped. The cirrus and vagina open irregu- larly, alternating right and left, in the middle or a little anterior to the middle of the proglottid margin. The cirrus-sheath scarcely equals Yq the proglottid breadth, often much less. The ductus ejaeulatorius (cirrus-canal) forms some convolutions in the proximal end of the cirrus-sheath and here widens out into a vesicula seminalis, 0.030 mm. 136 ILLINOIS BIOLOGICAL MONOGRAPHS [136 in diameter. The convolutions of the vas deferens outside of the cirrus- sheath are excentric on the porose side. In other species with a long cirrus-sheath this convoluted mass lies in the middle of the proglottid. The vagina is provided with a small sphincter muscle close to the vaginal opening. "Without broadening out into a reeeptaculum seminis the vagina passes into the ovarial region. The oocapt is very muscular. The uterine passage measures 0.02 mm. in diameter and the vitelline reservoir, 0.30 mm. The vitellaria are voluminous and follicular. The opening of the uterine passage and the well preformed uterine opening on the ventral side are found almost in the same transverse section posterior to the middle of the proglottid. The uterus has about eight branches on either side. Testes, numbering about 100 in each proglottid, lie irregularly in one or two layers. They measure about 0.150 by 0.075 mm. Ventral excretory vessels measure about 0.009 mm. in diameter, the dorsal vessels about 0.0025 mm. This species occurs only in An- guUla vulgaris and only in small numbers. In this connection the writer thinks it of interest to note that Creplin's specimens were taken at Greifswald in Prussia while Schnei- der's were taken in Finland. Geographically these habitats are not distant nor do any barriers exist to prevent the movement of the eels from one locality to the other. For this reason and because of anatomi- cal similarities it is extremely probable that Schneider's specimens were of the same species as Creplin's. It is to be noted that Dujardin's observations on the size of specimens taken from Anguilla vulgaris at Rennes, France, agree very well with those which Schneider describes. Nufer (1905) described and figured what he considered to be P. macro- cephala (Creplin). He found two specimens in the intestinal tract of a single Anguilla vulgaris from Lake Lucerne. Nufer shows such strik- ing inconsistencies in his statements and these agree so poorly with the findings of Schneider and the writer that it seems best to analyse parts of his paper. Compare his description of the head (Nufer 1905:137) and his statement aboul the head in his summary (Nufer 1905:145) with the facts presented in tabular form on pp. 146-147 of his paper where he compares P. macrocephalus, P. ocellatus, P. longicollis, and P. torulosus. All of these species he reports from Lake Lucerne. He writes (page 137) : "Der Scolex ist sehr gross, zietnlich breit, rundlich, und besitzt einen Durch- messer von 0.1512 mm. Gegen den Hals ist er scharf und deutlich abgesetzt imd iibertrifft alle ubrigen im Vienvaldsidttersee vorkommenden Proteocephalensco- lices an Grosse urn Bedeutendes (The italics are mine, La Rue.), weshalb Creplin, auch auf den Gedanken gekommen sein mag, diesen Proteocephalen mit "inacro- cephaluy' zu bezeichnen. Vorne ist der Skolex mit vier grossen, runden Saug- 137] PROTEOCEPHALIDAE—LA RUE 137 napfen versehen, die ihm die wuchtige Gestalt verliehen, wie ich sie sonst bei keinem Proteocephalen mehr angetrofFen habe. Je nach der Kontraktion der Saugnapfe erscheint ihr Rand kreisrund oder unregelmassig gelappt. Der aussere Durchmesser derselben betragt 0.069 mrn, der innere Durchmesser 0.0414 mm. Da der Skolex bei meinem Praparate etwas geschrumpft ist, war es mir unmoglich, einen fiinften, scheitelstandigen Saugnapf nachzuweisen, wie ihn von Linstow beobachtet haben will; jedoch ist sicher, dass eine Scheitelvertiefung vorhanden ist." Also in his conclusions note this (p. 145) : "Der Skolex iibertrifft die iibrigen Proteocephalenskolices an Grosse; dementsprechend ist aucb der Durchmesser der Saugnapfe grosser." In the tabulated data (pp. 146-147) Nufer gives the dimensions of the scolices and of the suckers of the four species thus: breadth of scolex of P. macrocephalus 0.151 mm., P. ocellatus 0.114 mm., P. lon- gicolUs 0.43 mm., P. torulosus 0,255 mm.; diameter of suckers of P. macrocephalus 0.069 mm., P. ocellatus 0.05 mm., P. longicollis 0.12-0.19 mm., P. torulosus 0.1 mm. According to these figures the diameter of the suckers and the breadth of the head of P. macrocephalus exceed the same dimensions as given for P. ocellatus only. It is smaller than either of the other two with which he compares it. Again note in the last sentence of the first paragraph quoted Nufer states that he could not find a fifth sucker, yet in his tabulated data (p. 146) he gives the diameter of the fifth sucker as 0.026 mm. In this he must be quoting from von Linstow 's description. Von Linstow was the first to mention a fifth sucker for this species. Evidently Nufer 's statements must lack accuracy. Nufer 's drawings are of little help in giving a clear idea of the systematic position of his specimens. Consider now his description of the male reproductive organs (pp. 140-142) and carefully compare his description with the writer's figure (Fig. 57). "Der Cirrusbeutel ist keulenformig; vorne an der Mundung schmal, erweitert er sich nach hinten ziemlich rasch und erhalt einen grossten Durchmesser von 0.094s mm. Am Hinterende ist er abgeru^^det und geht bis uber die Mitte des Gliedes hinaus. Wie von Linstow (1875) am Cirrus, so beobachtete ich am aussern Drittel des Cirrusbeutels eine Einschnurung, durch die er ungefahr die von V. Linstow angegebene Gestalt eines Kegels erhalt wie sie beim Kegelspiel ublich ist. Er dringt nicht vollkommen gerade in das Innere des Gliedes ein, sondern richtet sich etwas schrag gegen das Hinterende der Proglottids. Die Wandung des Cirrusbeutels wird von einer kraftig ausgebildeten Muskulatur umgeben. Aehnlich wie bei P'roteocephalus ocellatus heften sich an die Basis des Cirrusbeutels kraftig entwickelte Retraktoren, welche die biischelige VVurzelfasern an einem Bulbus sitzen. Der Raum zwischen der Wandung des Cirrusbeutels und Cirrus ist von zarten Bindegewebszellen und zahlreichen, unregelmassig 138 .ILLINOIS BIOLOGICAL MONOGRAPHS [138 \^rteilten Parenchymkemen erfullt; vielleicht sind auch einzelne kleine Kalk- korperchen eingestreut, wie sie von Kraemer (1892) bei Proteocephalus ocellatus gefunden worden sind. "Der Cirrus bildet die direkte Fortsetzung des Vas deferens; er durchbricht den Cirrusbeutel am Hinterende und durchzieht ihn in geradlinigem Verlaufe. Nachdem er den hintem Drittel des Beutels passiert hat, nimmt dessen Durch- messer ziemlich rasch ab und reduziert sich auf die Halfte. Nach den Beobach- tungen Kraemer's (1892) ist der Cirrus bei Proteocephalus ocellatus und P. torulosus in seinem hinteren Teile in mehrere Schlingen gelegt, wahrend er bei P. macrocephatus als vollstandig gestrecktes Organ auftritt. Gleichbedeutend wie diese Schlingen betrachte ich einige ringformige wulstige Verdickungen am hintem Drittel des Cirrus. Der Schmarotzer besitzt in ihnen jedenfalk eine Einrichtung, welche, ahnlich wie der in Schlingen gelegte Cirrus, dazu dient, bei der Begattung den Cirrus zu verlangern. Bei dem Geschlechtakte wiirden dann die ringformigen Wiilste sich glatten und successive verschwinden in dem Masse, als der Cirrus vorgestossen wird. Er ist von einer strukturlosen, glatten Wandung umgeben, der nicht wie bei P. ocellatus und P. torulosus nach hinten gekriimmte Chitinhakchen aufsitzen. Sein Lumen betragt im hintem Drittel 0.009 mm., nimmt aber nach vorn bedeutend ab. "Das Vas deferens liegt hinter und vor dem Cirrusbeutel etwas gegen den Seitenrand des Gliedes verlagert und bildet ein dichten Knauel, der sich besonders in der Lange der Proglottis ausdehnt ; die Schlingen, die mit Samenfaden erftillt sind, greifen kreuz und quer durcheinander. Die Wandung des Vas deferens ist viel zarter als diejenige des Cirrus und lasst keine besondere Muskulatur erkennen, "Die Hoden liegen als grosse, rundliche Gebilde im Mittelfeld des Gliedes zwischen den Dotterstocken, dem Keimstocke und dem vordern Gliedrande. Genauere Angaben iiber deren Zahl zu geben, ist wegen vorgeriickter Reife der Glieder unmoglich ; dagegen durften sie ihres grossen Durchmessers (0.054 rnm.) wegen kaum in grosserer Zahl auftreten. Bei Proteocephalus ocellatus, dessen Hodenblaschen beinahe gleichen Durchmesser (0.057 nim.) besitzen, fand Kraemer (1892) 27-30 in jeder Proglottis." It will be noted that in nearly every particular his description agrees with the writer's drawing (Fig. 57) and with his description of the male organs of P. fallax La Rue, parasitic in Coregonus fera. The work of the writer on P. fallax was done on material from Zschokke-s collection, and it seems that there can be no doubt that these specimens belong to the species described by Zschokke and Kramer as Taenia ocellata and by Nufer called P. ocellatus in his table. In the length and shape of the cirrus-pouch, in the position of the constriction of the pouch and in the inner bulbous end of the same Nufer 's description and the writer's draAving (Fig. 57) agree well. The circular swollen thick- ening which he notes in the posterior third of the cirrus can be best interpreted to be a coil in the ductus ejaculatorius. When such a coil is seen under certain conditions the appearance described by Nufer is 139] PROTEOCEPHALIDAE—LA RUE 139 simulated almost exactly. Likewise in the position of the mass of coils of the vas deferens, in the number, size and arrangement of the testes Nufer's description and his tabulated data (p. 146) agree very well with the writer's drawing and description of the same organs in P. fal- lax La Rue. His description of the male organs of the species in ques- tion cannot be said to agree with the writer's drawing (Fig. 49) wliich is a delineation of the proglottid of P. macrocephalus. Nor does his description agree with Schneider's or my own description of the pro- glottid of that species. Unfortunately the writer has not had the opportunity of examining Nufer's material of this species nor any other specimens of cestodes taken from the eels of Lake Lucerne. He cannot therefore make a positive determination of Nufer's form. The evidence at hand permits several interpretations. These are: 1, that Nufer permitted his cestode material from Anguilla to become confused with specimens of P. fallax from Coregonus fera; 2, that the Anguilla of Lake Lucerne harbor P. fallax; 3, that the ripe proglottids described by Nufer had been taken into the intestine of the eel with its food, perhaps Coregonus fera, liv- ing or dead. Supposition 1 is always a possibility when one is working with such material. Supposition 2 does not give complete satisfaction because if the eels of Lake Lucerne harbor P. fallax Nufer ought to have been able to find a fifth sucker, which he failed to do. The third supposition permits one to consider that Nufer's whole speci- mens were really P. macrocephalus but that the ripe proglottids (in reality from P. fallax) upon which he based his description of the pro- glottids became confused with the specimens of P. macrocephalus by natural means. The embryo of Nufer's form is about the size of the embryo of P. macrocephalus as determined by the writer. His meas- urement of the embryo was 0.0184 mm. while the embryos of the writer's specimens of P. macrocephalus measured 0.017-0.019 mm. and rarely as much as 0.021 mm. in an elongated embryo. The embryo of P. fallax is much larger, according to the writer's measurements being 0.0312- 0.0336 mm. in diameter. Thus far attention has not been called to Nufer's description of the female generative organs. He claims that the histological structure of the vaginae of P. macrocephalus and of P. ocellatus differs in some respects. The writer's own investigation of the two species, especially when the investigations of Kramer are taken into consideration, lead him to believe that the vaginae of the two species are much alike in histological detail. Nufer describes the ovary as being single, not bi- lobed. In this he has been led astray by a condition sometimes found in ripe end-proglottids. In such cases the lobes of the ovary may be 140 ILLINOIS BIOLOGICAL MONOGRAPHS [140 pressed backward until the ends of the lobes touch in the median line. In the investigations of the writer covering a large number of Proteoce- phalidae he has been unable to find a fusion of the ovarian lobes. He must conclude that Nufer's drawing of this condition is hardly trust- worthy. Nufer also claims that the waUs of the uterine pouches event- ually degenerate so that the eggs come to lie in the parenchjTna. There is reason to doubt the accuracy of this statement. Many sections of a large number of old ripe proglottids of P. macrocephalus and other species of this genus have been examined by the writer who has failed to find any such degeneration of the uterine walls. Nufer's material must have been in extremely poor condition, or else he wofully misin- terpreted the appearance of the sections. The foregoing discussion of Nufer's article leads to the conclusion that the complete specimens taken by Nufer from AnguUla vulgaris were probably P. macrocephalus, as he identified them. One must fur- ther conclude that a part of his description was based on the two loose end-proglottids which really belonged to P. faUax and that these were ingested with the food of the eel or that they were accidentally put with the cestodes of AnguUla during Nufer's manipulation of the sp>eci- mens. It also seems that the eggs which Nufer measured came from P. macrocephalus. Liihe (1909) gave a very short diagnosis of this form but included no figures of it. La Rue (1911:475) included this form in a list of Proteocephalus species and stated that Taenia dUatata was a synonym of P. macrocephalus. Some specimens which have been identified by the writer as P. macrocephalus were collected by Professor H. B. Ward in the course of a biological investigation of -Sebago Lake, Maine during the summer of 1907. This investigation was conducted under the auspices of the United States Fish Commission. Professor Ward examined 11 speci- mens of AnguUla chrysypa Baf. Of this number five had no cestode infection whatever; two yielded two Proteocephalids each; one yielded one Proteocephalid, and two others together yielded eighteen cestodes and some pieces. Of these eighteen cestodes eight were Proteocephalids. Some of the pieces also belonged to this group. Altogether then there were thirteen Proteocephalids plus some pieces but there was no com- plete strobUa among them. The specimens described are from bottles No. 47, 54, 56, 71 and 72 of the Sebago Lake collection. The worms are long and slender. No complete strobila was found but a fragment from the middle region of a worm measured 120 mm. long. The maximum breadth observed was 1.8 mm. Young proglottids are much broader than long, measuring 0.33 mm. broad by 0.022 mm. long. Mature proglottids are broader than long, measuring 1.0-1.20 141] . PROTEOCEPHALIDAE—LA RUE 141 mm. broad by 0.40-0.63 mm. long. The length of the ripe proglottids may exceed the breadth. They measure 0.90-2.08 mm. long by 0.491- 1.20 mm. broad. The head (Fig. 1) is very short. It has a slightly rounded apex which is not marked by grooves or furrows. The head is somewhat flattened dorsoventrally, being 0.320 mm. broad at the base of the suckers and about 0.150-0.160 mm. thick. At or slightly above its broadest zone the head bears the four almost spherical suckers which have a maximum diameter of 0.095-0.106 mm. The opening of the sucker measures 0.050-0.060 mm. Tho not measured the sucker cavity is fairly deep. The musculature of the suckers is moderately well developed. A fifth sucker is not present in this material, nor did Schneider or Nufer find one. It is replaced by a structure such as was described by the writer for P. filaroides and which was there called an endorgan. This structure is in reality a vestigial sucker. It has no elongated cells, tho Schneider says that he saw such cells, and there is no trace of muscles. In my specimens it is composed of a very few cells of irregu- lar shape surrounded by a membrane that is homologous with a basal membrane in other suckers. This vestigial fifth sucker is situated a few micra below the cuticula and it has no connection with the exterior. It measures 0.020-0.025 mm. This structure does not resemble the fifth sucker of P. percae for it has been shown (Figs. 8, 9, 120) that in P. percae this is a muscular organ which doubtless functions as a sucker. The neck is long and broad and thin. Frequently it measures 0.225-0.300 mm. or more in breadth while its length varies from 5.0 to 7.0 mm. The strobilation is quite evident. The notches between the segments are deep and the angles of the proglottids are somewhat rounded. Many shallow longitudinal folds give the surface of the worm a roughened appearance. The genital aperture is marginal, situated about the middle of the proglottid, and is irregularly alternating. There is no genital papilla. The excretory and nervous systems have not been carefully investigated. The musculature of the strobila is much as Benedict (1900) found it for P. amhloplitis tho the muscles are not as heavily developed. The testes (Fig. 49) lie in a single layer in the dorsal region of the medullary parenchyma between the vitellaria and anterior to the ovary. They are closely packed together until many of them are more or less polygonal in shape. They measure 0.063-0.074 mm. long by 0.042-0.063 mm. broad and they number from 100 to 120. The vas deferens forms a thick mass of coils extending from the middle of the proglottid to the very short cirrus-pouch. Schneider very well says that the mass of coils of the vas deferens is excentric lying on the side in which the 142 ILLINOIS BIOLOGICAL MONOGRAPHS [142 cirrus-pouch is situated. The cirrus-pouch (Figs. 47, 48, 49) is very- short, reaching just a little way through the vitellaria. Its length is about 0.160 mm. making the ratio of its length to the proglottid breadth about 1 :6 to 1 :8. The cirrus-pouch is bent up toward the inner dorsal wall of the dermo-muscular sac. Within the cirrus-pouch the ductus ejaculatorius forms but one or two coils before passing over into the short, but thick-walled cirrus. The cirrus is straight, ft was not pro- truded in any specimens examined by the writer. The vagina lies anterior to the cirrus-pouch, but the opening of the vagina into the genital atrium is situated almost dorsal to that of the cirrus (Fig. 48). Very near the opening of the vagina there is a weak sphincter vaginae. The lumen of the vagina in its initial region is quite lai^. This however soon constricts and the remainder of the vagina is of small diameter. The drawings (Figs. 47, 48) show how the vagina which opens anterior and dorsal to the cirrus-pouch passes over the latter in its course to the ventral surface and then backward to the ovary. Several species of Proteocephalus, e. g., P. percae, P. pinguis, and P. exiguus show this twisting of the vagina part way round the cirrus-pouch. This point has not been investigated in many species but it seems probable that it is quite a constant character of the genus. The broadened region of the vagina bears a ciliated lining on its inner surface but the presence of the cilia could not be demonstrated throughout the length of the vagina. A small receptaculum seminis was found a little way anterior to the mid-piece of the ovary. The ovary (Fig. 49) is a heavj' bilobed structure of much the same shape as in P. percae or P. cernuae tho shorter in those species. The viteUaria are long follicular ma^es iii the lateral fields- of the proglottids. The follicles are closely compacted. An oocapt possessing a heavy muscula- ture is present, also an oot}i)e with its surrounding shellgland. The uterus (Fig. 47) in ripe proglottids is made up of a median tube with 7-11-12-14 lateral outpocketings on either side. The septa between the uterine pouches are sometimes very thin and in other cases quite thick. The uterine passage is a small tube which after a sinuous course empties into the uterus about the middle of the proglottid. The uterine openings are 1-2 in number. Schneider in his specimens found only a single uterine pore. In reality this difference between the find- ings of Schneider and the writer is slight and too inadequate to serve as a basis for a specific distinction- A second uterine pore is very read- ily overlooked. Especially is this true in some species in which the second pore when present is smaller than the first and is situated some distance from it. The eggs were taken from the uterus of alcoholic specimens. The thin outer hyaline shell, characteristic of the e^s of 1431 PROTEOCEPHALIDAE—LA RUE 143 many species, could not be demonstrated. The outer shell, in this case corresponding to the second shell of most Proteocephalus species, was thick and quite granular. It measured 0.026-0.036 mm. in diameter, 0.026-0.029 mm. being the more common dimensions. The embryo, itself, varies from spherical to ovoidal. The diameter varies from 0.017 to 0.019 mm. and rarely 0.021 mm. for a long oval embryo. The identity of this species with Linton's T. dUatata has already been discussed. Whether it is the same as P. hemisphaericus cannot now be determined. A discussion of its relationship to that form is given under the description of P. hemisphaericus. Proteocephalus mac- rocephalus shows no marked resemblances to any other of the North American species of Proteocephalus. In some respects it shows some marked resemblances to P. cernuae La Rue but it differs from that species in lacking a fifth sucker, in the possession of many more and larger testes, in having a cirrus-pouch that is much shorter actually and relatively, in having a much more voluminous mass of vas deferens and in having smaller embryos. The proportions of the proglottids are also different. While in some respects this species resembles P. percae its lack of a fifth sucker readily differentiates these two species. Moreover its very short cirrus-pouch is in marked contrast with the very long cirrus-pouch of P. percae. This species is very different from P. torulo- siis in size, in the arrangement of the testes, in the size of the cirrus- pouch and in the number of uterine pouches. PROTEOCEPHALUS AMBLOPLITIS (Leidy) [Figs. 18, 19, 116, 117, 134a & b, 183] 1887 : Taenia amhlopUtis 1887: Taenia micropteri 1896 : Ichthyotaenia amhlopUtis 1897: Taenia ocellata 1900 : Proteocephalus amhlopUtis 1905 : Proteocephalus amhlopitis 1909 : Proteocephalus sp. 1911 : Proteocephalus amhlopUtis Specific Diagnosis: Characters of the genus. Cestodes large, 280- 410 mm. long, 2.-2.5 mm. in maximum breadth. Surface of body rough, with transverse and longitudinal furrows. Scolex prominent, 0.57-0.88 mm. broad, divided into quadrants by deep grooves. Tip of scolex usually marked by a minute depression with a slight elevation in the Leidy 1887 :22-23 Leidy 1887 :23 Riggenbach 1896 :267-268 Linton 1897 :425-426 Benedict 1900:339:355 Marshall and Gilbert 1905 :513-522 La Rue 1909:21,25, 27, 28, 31, 36 La Rue 1911:475 144 ILLINOIS BIOLOGICAL MONOGRAPHS [144 center. Suckers large, round or oval in outline, deep, directed outward and anteriad. Length of suckers 0.300-0.400 mm. Fifth sucker vesti- gial, deeply embedded in tissue of head. Proglottids closely joined to- gether, corners rounded. Young proglottids 12-15 times broader than long. Mature and ripe proglottids broader than long, about quadrate, or rarely longer than broad. Genital sinus irregularly alternating, marginal, situated about end of first fourth of the proglottid. Vagina opening anterior to cirrus- pouch. Vaginal sphincter long and very thick. Receptaculum seminis present. Uterus with 15-20 lateral outpocketings on either side. Cirrus- pouch pyriform, muscular, 0.400-0.500-0.650 mm. long, reaching ^/y-Vs across the proglottid breadth. Cirrus, when protruded, long and slen- der. Ductus ejaculatorius much coiled. Vas deferens forming a great mass of coils extending to, or past, the middle of the proglottid. Testes 70-100 in number, situate between vitellaria. Eggs provided with three membranes. Outermost membrane hyaline, ellipsoidal, 0.036-0.043 mm. in diameter; second membrane thick, granular, 0.022-0.024 mm. in diameter; third closely investing the embryo; embryo 0.0168-0.018 mm. in diameter. Habitat : Intestine of host. Host Locality Collector Authority Ambloplites rupestris Lake George, N. Y. Jos. Leidy Leidy (type host) (type locality) 1887 :22-23 Micropterus Salmoides = Lake George, N. Y. Jos. Leidy Leidy nigricans (type locality) 1887 -^s Ambloplites rupestris J. W. Milner Linton 1897 ■■425-426 Micropterus dolomieu Lake St. Clair, Mich. H. B. Ward Benedict 1900 :339-355 Micropterus dolomieu Lake Mendota, Wis. Marshall & Marshall & Gilbert Gilbert 1905 ■.513-522 Micropterus salmoides Walnut Lake, Mich. T. L. Hankinson La Rue (The present paper) Micropterus salmoides Pelican Lake, Minn. E. G. Davis La Rue (The present paper) Amia calva Lake Erie H. B. Ward La Rue (The present paper) Atnia calva Lake St. Clair, Mich. H. B. Ward La Rue (The present paper) 145] PROTEOCEPHALIDAE—LA RUE 145 This species was first described by Leidy (1887:22-28). His speci- mens were secured from the stomach of Amhloplites rupestris, Lake George, New York. His diagnosis reads: "Taenia AmblopHtis. — Head quadrate, spheroidal, consisting almost entirely of the four large spherical bothria, with the summit slightly prominent and conical or depressed and unarmed ; neck very short or none ; body compressed cylindrical, gradually widening from the head to near the posterior part, where it slightly narrows to the end ; segments linear, becoming gradually longer and wider, and the more quadrate, all deeply and pretty regularly wrinkled into two or three annuli. Genital apertures obscure. Length 8 to 12 inches; in alcohol contracted to 2% to 5 inches ; greatest width 2 mm. "Head 0.5 to 0.625 mm. long and 0.75 to 0.875 broad. Bothria 0.375 mm. diameter. Commencement of body 0.625 wide. Anterior segments 0.125 long, 0.625 wide; subsequently 0.375 long and 1.5 to 1.875 wide; posterior segments 0.75 long by I mm. wide. "A number of specimens from the stomach of the Rock Bass Ambloplites rupestris. Lake George, New York. "This species resembles the Taenia ocellata Rudolphi of the European Perch, Perca fluviaiilis, and perhaps is the same." Leidy 's drawings of the head and proglottids are reproduced (Figs. 134a and b). Immediately following his report on Taenia amhloplitis Leidy (1887:23) reported Taenia micropteri from the intestine of Mi- cropterus salmoides (nigricans) Lake George, N. Y. m the following words : "Taenia Micropteri. — Head large, compressed spheroidal, with four subter- minal spherical bothria and a papilliform unarmed summit ; neck none ; body ob- scurely segmented, and with no obvious internal organs, posteriorly variably nar- rowed and obtusely rounded at the end. Length from half an inch to an inch, and about i mm. wide. Apparently a larval form ; found in the body cavity of the Black Bass, Micropterus nigricans. Six worms, soft, white, and active. The longer ones of an inch would elongate to double the length, becoming proportion- ately narrower. The head, about i mm. or more in diameter, varied in length and breadth, according to contraction, sometimes one and sometimes the other being the larger. Lake George, N. Y." This form is probably the larval form of P. amhloplitis. In dimen- sions and in general character the two forms are very much alike, even to the papilliform unarmed summit of the head. The obscure segmen- tation was probably due to wrinkling, not to a true segmentation. P. anibloplitis is the only adult Proteocephalid reported from Micropterus dolomieu and M. salmoides and it is known to occur in a closely related host species in the same lake in which Leidy found Taenia micropteri. This is additional evidence in support of the view that Leidy 's species 146 ILLINOIS BIOLOGICAL MONOGRAPHS [146 are identical. In the light of the evidence the name Taenia micropteri is to be considered a synonym of Taenia amhloplitis and it should be stricken from the list of valid species because of the priority of the latter named species. Eiggenbach (1896:267-268) put this species in his list of Ichthyo- taenia yet he considered it a doubtful form. Under the name Taenia ocellata Rud. Linton (1897) described this species from Ambloplites rupestris. His data agree very well with the data of Leidy, Benedict, and the writer. A difference in the length of the neck caused Linton to doubt the identity of his form with Leidy 's T. amhloplitis. This difference is easily explained in forms so contractile and so wrinkled as these. Linton himself says, "My specimens agree with Doctor Leidy 's pretty well except in the character of the neck. In T. amhloplitis the neck is described as 'short or none'. In my specimens the neck is long." Again in concluding Linton writes, ''This reference of these Taenia of Amhloplites to the species T. ocellata is provisional only. I think, how- ever, that there can be little doubt but that my specimens are identical with T. amhloplitis Leidy. The apparent absence of neck in Leidy 's species may be ascribed to the presence of strong transverse wrinkles, due probably to the action of the preserving fluid." Benedict (1900: 339-355) working in Dr. H. B. Ward's laboratory redescribed this spe- cies using Leidy 's specimens for comparison with material which Pro- fessor Ward had collected from Micropterns dolomieu while engaged in a biological investigation of Lake St. Clair in August, 1893. Benedict by means of the section method demonstrated that, despite some dis- crepancies in size, his specimens and Leidy 's agreed in anatomical and histological details. Marshall & Gilbert (1905: 513-522) found this spe- cies in Micropterns dolomieu but not in other hosts from Lake Mendota, Wis. La Rue (1909:21 et seq.) referred to a cestode found in Microp- teris salmoides as P. sp. and in a footnote on the same page (p. 21) says, "This form may prove to be Proteocephalus amhloplitis Leidy, which it very much resembles". That species is now known to be P. amhloplitis Leidy. These specimens are referred to in the present arti- cle as No. TLH947 and No. TLH1036, collected by Hankinson. La Rue (1911:475) included this species in a list of species of Proteocephalus. The following description of this species is based partly on Bene- dict's (1900) description and largely upon the writer's own work on material which Professor T. L. Hankinson had sent to Professor Ward for determination. This material was collected from the intestine of Micropterns salmoides in the course of a biological investigation of Walnut Lake, Michigan, summer of 1906. Other specimens have been 1471 PROTEOCEPHALIDAE—LA RUE 147 examined and identified as belonging to this species as follows: in un- numbered bottle, collection of La Rue, labelled "Black Bass, Large mouth. Pyloric Region, Pelican Lake Minn., 1909," collected by E. 6. Davis; in bottle No. 10.151 labelled "Ex dogfish, Sandusky 0. Jy. 7, 1905"; in bottle No. 2d labelled "7/10/01. P. in B. Host. Amia calva- Intestine" ; in bottle No. 85 "7/12/01. P. in B. Amia calva. Intestine" ; in bottle No. 295, "8/4/01. P. in B. Amia, Stomach." The abbreviation *P. in B.' stands for Put-in-Bay, Ohio, the locality of collection. The bottles numbering 10.152, 2d, 85, 295 are in Professor Ward's collection. These together with the material collected by Hankinson were turned over to the writer for study through the kindness of Professor Ward. This is one of the largest of the species of Proteocephalus and it is the largest species of that genus known at present from the fishes of North America. It may attain a length of 41 cm. and maximum breadth of 2.0-2.5 mm. The body is thick, fleshy and heavily muscled. In pre- served specimens the outlines of the worm are somewhat rough, due to the furrows on the margins of the strobila. The surface of the worm is also rough. Longitudinal and transverse furrows are frequent. Espe- cially noticeable is a deep median ventral furrow. On account of these furrows the strobilation is more or less indistinct. Likewise the poste- rior limit of the neck is frequently obscured by numerous transverse folds which give an appearance of segmentation. The head is large and prominent. Its breadth is 0.75-0.875 mm. according to Leidy, 0.82-0.88 according to Benedict. The heads exam- ined by me measured 0.57-0.60 mm! Benedict describes the shape of the head thus: "From the anterior face it presents a nearly square outline, with a deep notch in the middle of each side, dividing the surface into quarters. Each quarter contains a large sucker which is directed outward and upward. The apex of the head is a smooth, rounded prominence with a small depression in the top. No hooks are present. A fairly good idea of the shape of the scolex can be obtained by placing two truncated pyramids base to base. One of the smaller bases will represent the beginning of the neck, the other the prominence, while on the slope just beneath this would lie the suckers. The notches seen in the anterior view of the scolex form furrows down the four sides of the head, which gradually de- crease in depth and vanish on the first few proglottids." Frequently the head is more globose than Benedict describes it. Such heads are figured (Figs. 18, 19). The small apical papilla may not always be seen but the furrows have been present in all heads examined by me. Leidy 's figure of the head, reproduced (Fig. 134a), is somewhat similar to mine. It, however, does not show the furrows. Two of Bene- dict's figures of the head have been reproduced (Figs. 116, 117) for purposes of comparison. 148 ILLINOIS BIOLOGICAL MONOGRAPHS [148 The suckers which are deep and well muscled measure 0.30 mm. in length with a sucker opening of 0.150 mm. in my specimens. Leidy's measurement of the suckers was 0.375 mm. long and Benedict's was 0.32 mm. broad by 0.40 mm. long. In suckers of this size differences in contraction states will explain the variation in size. There is no func- tional fifth sucker but deep in the tissue of the head a peculiar structure (Fig. 116) may be found which is a vestigial fifth sucker. Benedict saw the structure but was unable to point out its significance. The neck is short and 0.25-0.45 mm. wide. The first proglottids are much broader than long measuring 0.344 mm. broad by 0.022-0.028 mm. long. Mature and ripe proglottids are broader than long as a rule, but at times may be quadrate, or even longer than broad. The last condition is rare. The maximum breadth of mature and ripe proglottids is 1.5-2.0-2.5 mm. while the maximum length of the same is 0.5-1.0-2.0 mm. The cuticula, the musculature, and the nervous system were care- fully investigated by Benedict (1900) who found nothing especially re- markable about these structures. The excretory system differs from that of P. fossatus (Rigg.) and Corollabothrium lohosum Rigg. in hav- ing no definitely placed foramina secundaria. At irregular interv^als along either dorsal or ventral excretory vessel arise numerous branches which take a fairly direct course to the exterior. These branches are of various sizes and the lumen of each undergoes considerable variation in size in its course. The duct through the cuticula is very small and not beset with small bristles as Kraemer (1892) described for the species which he determined to be P. filicollis. No special musculature can be found in the course of these ducts to the exterior. The main longi- tudinal excretory vessels are four in number. They are situated just within the dermo-muscular sac. The ventral vessel has the larger lumen and it is further differentiated from the dorsal vessel by its verj' thin membranous lining. The dorsal vessel has a lining apparently made up of columnar epithelial cells. Rarely, however, the dorsal vessel is di- lated to a size equalling that of the ventral vessel and in these cases the structure of the walls of the two vessels appears to be identical. No transverse vessel connecting the ventral or dorsal vessels in the poste- rior part of the proglottid has been found. In the scolex there is an intricate plexus of excretory vessels. Many ducts opening to the exte- rior by small pores place the coils of this plexus in communication with the exterior. The common marginal genital sinus opens about one fourth of the length of the proglottid from the anterior end. It is irregularly alternate in position. A genital papilla is not present. The vagina opens into the sinus anterior to the cirrus-pouch. The testes are spheroidal bodies, 149] PROTEOCEPHALIDAE—LA RUE 149 0.050-0.065 mm. in diameter, which are sometimes rendered polyhedral by pressure of adjacent testes. They number from 75 to 100 and are crowded into one or two irregular layers in the space between the vitellaria and anterior to the ovaries. The vas deferens (Fig. 183) forms a large mass of coils beginning in the mid-field of the proglottid and reaching to the cirrus-pouch. A large part of this mass of vas deferens is posterior to the cirrus-pouch. The cirrus-pouch (Fig. 183) is a large pyriform structure, heavily muscled with both longitudinal and circular muscles. Its larger and inner end is attached by heavy muscle strands to the dermo-museular sac. It measures 0.40-0.50-0.65 mm. long by 0,150-0.230 mm. in maximum breadth. The ratio of its length to the proglottid breadth varies from 2:7 to 2:5. When it is protruded the cirrus is long and slender, a little larger at the base than at the tip but when within the cirrus-pouch the basal part of the cirrus has a broad lumen. This sharply defines the cirrus from the slender ductus ejaculatorius which forms an intricate mass of coils. The vagina (Fig. 183) always lies anterior to the cirrus-pouch. Very near its opening the vagina dilates markedly and in this region it is provided with a thick and powerful sphincter vaginae measuring about 0.030 mm. thick by 0.300 mm. long. This prominent sphincter surrounding the greatly dilated vagina renders the latter a striking feature of the proglottid and makes a valuable diagnostic character for the species. At the inner limits of the sphincter the vagina contracts sharply and beyond the constriction it again dilates. Here its inner surface is weakly ciliated. Anterior to the ovary the vagina may describe a few coils before it passes into that portion of its length which is differentiated into a small receptaculum seminis. Entering the inter- ovarial space the vagina describes a few coils and then discharges into the oviduct. The ovary (Fig. 184) is situated in the posterior part of the proglottid. It is bilobed, each lobe being thick, broad and somewhat club-shaped. The lobes extend laterad to the vitellaria. From the mid- piece of the ovary arises a muscular organ, the oocapt or gulping organ. From the oocapt arises the oviduct which after making one or more coils is joined by the vagina. From this point the oviduct extends to the ootype. Just as it enters the ootype the oviduct receives the common vitelline duct which has been formed by the union of the paired vitelline ducts arising in the posterior part of the vitellaria. The ootype is surrounded by the so-called shell-glands, the indi- vidual cells of which are long and clubshaped. The ootype discharges into a somewhat muscular duct known as the uterine passage which extends anteriad passing the ovary on the dorsal side. It discharges into the uterus from the dorsal side of the latter at a point about 0.080-0.110 ISO ILLINOIS BIOLOGICAL MONOGRAPHS [150 mm. anterior to the ovary. Benedict (1900) stated that there was no uterine passage in this species. An examination, however, of his slides and reconstruction drawings convinced the w^riter that a uterine passage was present in Benedict's specimens as it was in his own. The vitellaria are lateral and follicular. In this species they do not extend posterior to the lobes of the ovary nor do they parallel the posterior margin of the proglottid. The uterus in young proglottids is a median ventral tube from which later 15-20 lateral outpocketings develop on either side. Benedict's drawing reproduced (Fig. 183) shows but a part of the pouches. There are 1-2-3 preformed uterine pores. The uterine eggs are covered with three membranes, an outer, thin hyaline, a middle thick and granular membrane and an inner thin membrane closelj investing the embryo. The outer membrane which is not spher- oidal but ellipsoidal measures about 0.036-0.043 mm. in length. The middle shell is spherical 0.022-0.024 mm. in diameter. The embryo measures 0,0168-0.017 mm. in diameter. The American forms which most resemble this species are P. per- plexus LaRue and P. nematosoma (Leidy). The latter may be the same as P. amhloplitis. P. perplexus, however, is distinguished from P. ambloplitis by its smaller head, smaller suckers, thin- ner and smaller strobila, by the smaller size and the different loca- tion of its sphincter vaginae, by the posterior prolongation of its vitellaria, by its much smaller cirrus-pouch, by its fewer coils of ductus ejaculatorius, by its larger number of testes, and by the smaller size of the eggs. P. ambloplitis greatly resembles P. nematosoma. It differs from that species chiefly in the somewhat larger size of the head and suckers. P. amhloplitis is larger than most of the old world species of Proteocephalus and it differs from a large number of these in not pos- sessing a fifth sucker. It resembles P. torulosus in the lack of a function- al fifth sucker and in size. It may be easily differentiated from P. toru- losus by reason of its larger head and suckers, by its sphincter vaginae which for size and length is unique in the genus, by its more numerous uterine pouches, and by the different arrangement of testes. P. amhloplitis may be distinguished from all other known species of Proteocephalus by means of its extremely large sphincter vaginae which because of its length and its extraordinary development is re- markable. This species is also readily distinguished from all other species of the genus by reason of the large number of coils of the ductus ejaculatorius. 151] PROTEOCEPHALIDAE—LA RUE 151 PROTEOCEPHALUS PERPLEXUS La Rue [Figs. 17, 64, 65] ? 1886 : Taenia fiUcollis Leidy, 1886 :62-63. 1911 : Proteocephahis perplexus La Rue, 1911 :478-479. Specific Diagnosis: The characters of the genus. Observed length as much as 15.5 cm. Maximum breadth 1.7 mm. Strobilation evident. Angles of proglottids sharp and distinct. First proglottids much broader than long. Mature proglottids broader than long, 1.70 mm. broad by 0.595 mm. long. Ripe proglottids quadrate or longer than broad, 1.02 mm. broad by 1.10 mm. long to 1.75 mm. long by 0.510 mm. broad. Head somewhat spheroidal, flattened dorsoventrally, divided into four quadrants by grooves extending nearly to the apex. At apex frequently a small papilla situated in a small depression. Head 0.663-0.714 mm. broad, 0.425-0.510 mm. long. Suckers four, 0.340-0.459 mm. long by 0.255-0.272 mm. broad. Cavity of sucker deep. No fifth sucker, no rostellum. Neck broad and thick, about 0.5 mm. long. Genital pore marginal, situated at end of first fourth or half of proglottid, irregularly alternating. No genital papilla. Cirrus-pouch elongated oval in shape, 0.30-0.344 mm. long, extending %-i/4-% across the proglottid. Ductus ejaculatorius with 1-3 coils. Cirrus when pro- truded spindle-shaped, slender, thicker at base, 0.60 mm. long. Testes 135-155 in number, in one layer occupying dorsal field between vitellaria anterior to ovary. Testes 0.069 by 0.037 mm. in diameter. Vagina anterior to cirrus-pouch, never crossing same, beginning region dilated. Inner surface of vagina heavily ciliated. Vitellaria follicular, volumi- nous, follicles of same large, compacted. Portion of vitellaria parallel- ling posterior margin of proglottid. Ovarian lobes thick, heavy, irreg- ular. Uterus, when developed, possessing 20-25 lateral pouches. Ute- rine pores 2-4. Uterine eggs provided with three membranes. Inner and outer membranes thin, second thick, granular, sometimes partially or wholly split into two layers. Embryos 0.013-0.014 mm. by 0.014- 0.0156 mm., second membrane 0.019-0.030 mm., outer membrane 0.024- 0.036 mm. in diameter. Habitat : In intestine of host. 152 ILLINOIS BIOLOGICAL MONOGRAPHS [152 Host Locality Collector Authority Amia calva L. Illinois river, H. B. Ward La Rue (Present paper) (type host) Havana, III. (type locality) ? Amia calva L. North Carolina Jos. Leidy La Rue (Present paper) Lepisosteus Illinois river H. B. Ward La Rue (Present paper) platostomus Type: Alcoholics No. Ha89a and slides from the same lot. Co- types :— Ha 10 a ; Ha 10 e ; Ha 29 a ; Ha 30 h ; Ha 77 a, b, e ; Ha 94 e, h, and slides of Ha 94 h, in Dr. H. B. Ward's Collection. Leidy (1886:62-63) found some specimens of a cestode in Amia calva from North Carolina. These specimens, he thought, might be Taenia filicollis Kud. His specimens, judging from his data probably belong to the species P. perplexus but since Leidy published no draw- ings of his specimens no positive determination can be made. That part of his report containing his data is here quoted : "The worms accorded with the description of the Taenia filicollis, infesting Sticklebacks, Gasterosteus, and is probably the same species. They range from iH to 3 inches long, gradually widening from the delicate thread-like neck to the posterior rounded extremity, where they measure from i to 1.5 mm. wide. The head is spheroidal, variably broader or longer, and about 0.625 mm., with the summit slightly prominent and unarmed and with four hemispherical, lateral both- ria 0.25 mm. in diameter. Neck variable, when extended long and narrow and usually about half the width of the head. Anterior segments, transversely linear, about an eighth the length of the breadth, gradually becoming inverted saucer- shaped or scutellate, and about one-fourth the length of the breadth. Posterior segments more quadrate, slightly widening behind, about 0.75 mm. long and from 1 to 1.5 mm. broad; last segment longest and rounded. Genital apertures mar- ginal." La Eue (1911:478-479) briefly described this species and gave it the name Proteocephalus perplexus. The specimens upon which this species is based were collected at Havana, 111., June and July 1910, by Dr. H. B. "Ward. The hosts Amia calva and Lepisosteus platostomus were caught in the Illinois river at that place. Four Amia were exam- ined, three were infested with 30,10 and 15-20 specimens of P. perplexus respectively. One was uninfested. Eight gars were examined; three were infested with 6, 3 and 5 specimens of P. perplexus respectively. Five of the gars were not infested with this species. In all the Amia 153] PROTEOCEPHALIDAE—LA RUE 153 and in one of the infested gars the P. perplexus was not accompanied by any other species of Proteocephalus. In two of the gars P. singu- laris occurred together with P. perplexus. Nothing is known regarding the seasonal distribution of the parasite and almost nothing regarding its geographical distribution. It has not been found in the Amia of the Great Lakes which Professor Ward examined a number of years ago. In those specimens were found P. amhlopUtis. Judging from external appearances alone these specimens of P. perplexus are very much like specimens of P. amhlopUtis. Even after staining and mounting some pieces in toto they appear to belong to that species tho certain points of difference may be indistinctly made out. Examination of sections revealed certain characters by which the two species may be differentiated. The writer (1911:478) proposed the name Proteocephalus perplexus for this species by reason of the diffi- culties attending its differentiation from its nearest congener. In size P. perplexus is somewhat smaller than P. amhlopUtis. Its strobila is shorter, narrower and thinner. Its head is a little smaller than that of P. amhlopUtis but is very similar in shape and it has four grooves as does that species. Sometimes the minute papilla at the apex of the head thought to be characteristic of P. amhlopUtis may be seen. The suckers are large and in a position similar to that which they occupy in P. amhlopUtis. The head (Fig. 17) is somewhat spheroidal. It is flattened dorso- ventrally and is evenly rounded anteriorly. Four grooves extend from the base of the head nearly to the apex where frequently there is a small papilla in a shallow depression. The head is not as truncate as the head of P. amhlopUtis described by Benedict (1900). It resembles very closely heads which the writer has examined and drawn (Figs. 18, 19) of the latter species. Four heads of P. perplexus measured in breadth and length 0.663 by 0.510 mm., 0.697 by 0.425 mm., 0.697 by 0.510 mm., 0.714 by 0.459 mm. The suckers measured 0.340-0.459 mm. long by 0.255-0.272 mm. broad. There is no fifth sucker and no rostel- lum. Sections through the apex of the head failed to reveal even a vestige of a fiifth sucker. In P. amhlopUtis the rudimentary fifth sucker is large. The suckers are deep and well muscled, usually longer than broad. The sucker-opening is directed outward and slightly forward. The neck is 0.5-0.6 mm. long. It is broad and thick but narrower than the head. No complete strobila was found yet most of the longer pieces contained ripe proglottids. Six pieces with heads measured 65, 91, 106, 105, 125, and 155 mm. long respectively. The maximum breadth ob- served was 1.7 mm. 154 ILLINOIS BIOLOGICAL MONOGRAPHS [154 The worm shows a very evident strobilation, the angles of the pro- glottids being sharp and well marked. The posterior border of one proglottid overlaps the anterior end of the one following. Segmenta- tion begins about 0.5-0.6 mm. from the head. Here the segments are much broader than long. Gradually the length increases in proportion to the breadth until in nearly mature proglottids the dimensions may be 1.70 mm. broad by 0.595 mm. long. Further down the strobila nearly ripe proglottids may be about quadrate 1.02 mm. broad by 1.10 mm. long. Ripe proglottids are longer than broad, 1.75 mm. long by 0.510 mm. broad. In all but ripe proglottids the genital pore is not promi- nent but in these long proglottids the pore is situated on an eminence. Moreover in this part of the strobila the posterior region of the seg- ment is much broader than the anterior or middle region. The neck is 0.5-0.6 mm. long. It is broad and thick, not as broad, however, as the head. The genital pore is situated on the lateral margin at the end of the first one-fourth to one-half of the proglottid. The pores alternate irreg- ularly. In mature and nearly ripe proglottids there is no genital papilla but in elongated ripe proglottids a genital prominence is noted. Into the common genital sinus both vagina and cirrus open, the vagina always anterior to the cirrus. The male organs (Fig. 65) much resem- ble the male organs of P. anibloplitis but here again certain differences exist. The cirrus-pouch in P. perplexus is not as voluminous nor as long as in P. amhloplitis. It measures 0.300-0.344 mm. long. Its length goes into the proglottid breadth 3-4-5 times depending somewhat upon the state of contraction of the proglottid. "Within the cirrus-pouch are 1-3 coils of ductus ejaculatorius, a much smaller number than in P. amhloplitis. The coils of the vas deferens outside the cirrus-pouch are very numerous. They form in mature proglottids a thick compact mass extending from the cirrus-pouch to the middle of the segment. The cirrus itself is well muscled. When protruded it is a long spindle- shaped organ slightly thicker near the base than elsewhere. It is nearly 0.60 mm. long. The testes are very numerous, 135-155 in number. They are arranged in one layer, occupying the entire dorsal field anterior to the ovaries and as far laterad as the vitellaria, with the exception of the small region taken up by a portion of the cirrus-pouch and the vas deferens. The testes measure as much as 0.069 mm. long by 0.037 mm. broad, their short axis Ijang parallel to the long axis of the worm. The vagina (Fig. 64) in its first part is considerably dilated. Throughout the full length of this dilated region there is a weak cir- cular musculature. At the end of the dilatation is a strong sphincter vaginae 0,053 mm. long and 0.015 mm. thick. P. amhloplitis has a long 155] PROTEOCEPHALIDAE—LA RUE 155 and extremely heavy sphincter vaginae while in P. singularis the sphincter vaginae resembles that of P. perplexus. Throughout its length as far as the receptaculum seminis the inner surface of the vagina is heavily ciliated. The vagina does not cross the cirrus-pouch, but after reaching the mid-field of the segment it takes a sinuous course posteriad to the interovarial space. A small receptaculum seminis lies just anterior or posterior to the mid-piece of the ovary. The vagina forms no coils anterior to the ovary. The vitellaria (Fig. 64) are voluminous, the follicles are of good size and closely packed together. They extend not only to the extreme posterior margin of the proglottid but are bent around and lie parallel to the posterior margin nearly to the mid-field. This is particularly noticeable in ripe proglottids. The paired vitelline ducts pass through this posterior continuation of the vitellaria. The ovary is bilobed. The lobes are thick and heavy, with a some- what irregular outline due to protuberances. In sections it is noted that the ovary is not a solid organ but is made up of smaller parts more or less fused together. An oocapt, ootype, shell gland and other organs usually found in the inter-ovarial space in Proteocephalids are found here and in the relations characteristic of the genus. The uterus (Fig. 64), a median tube in mature proglottids, is made up in ripening pro- glottids of a median tube and 20-25 narrow lateral pouches. These pouches occupy the entire ventral field between the vitellaria and the anterior and posterior proglottid limits. There are 2-4 ventral uterine pores. The uterine eggs have three membranes, an inner one closely investing the embryo, a middle membrane, quite thick and granular and frequently partially or completely split into two layers, and an outer membrane thin and hyaline. The embryo measures 0.013-0.014 mm. by 0.014-0.156 mm., being usually somewhat elongated but at times spheroidal. The second membrane measures 0.019-0.030 mm. and the outer one 0.024-0.036 mm. in diameter. The excretory system is made up of four main lateral canals which traverse the length of the strobila. The two ventral vessels are larger than the two dorsal. At intervals small branches arise from the main vessels and lead to the exterior. No transverse excretory commissure was observed. In the head and neck the anastomoses of the excretory system are very complex. The main trunks are nearly straight. This species is closely allied to P. amhloplitis yet it differs from that species in size, in the lack of a vestigial fifth sucker, in the size and location of the vaginal sphincter, in the posterior prolongation of the vitellaria, in the smaller cirrus-pouch, in the fewer coils of ductus ejac- ulatorius within the cirrus-pouch, in the greater number of testes and 156 ILLINOIS BIOLOGICAL MONOGRAPHS [156 in the size of the eggs. In size P. perplexus somewhat resembles P. singularis. It also resembles P. singularis in the shape and proportions of its proglottids and in the character of the vagina and vaginal sphinc- ter. These two species differ in the size and shape of the head, suckers, and neck. Tho nearly of the same size the strobila of P. perplexus is the larger. P. perplexus has more numerous testes, a larger cirrus- pouch and more numerous coils of ductus ejaculatorius. The main excretory vessels of P. perplexus are straight, but they are very sinuous in P. singularis. P. perplexus differs from all the European species in the position of the sphincter vaginae and in the extension of the vitel- laria along the posterior border of the proglottid. PROTEOCEPHALUS SINGULARIS La Rue [Figs. 24, 25, 39-41, 83-87] 1911 : Proteocephalus singularis La Rue, 1911 :479 Specific Diagnosis: Characters of the genus. Strobila long and slender. Observed length up to 170 mm., length probably as much as 250 mm. in complete individuals. Maximum breadth up to 0.90-1.0 mm. Head small, 0.250-0.30 mm. broad by 0.20-0.22 mm. long. Head bear- ing at broadest part four large suckers. Apical region of head fre- quently prolonged into an unarmed rostellum-like organ. Deep grooves between suckers. Suckers of variable shape, always with pointed apex, with shallow cavity and thin muscular wall. Length of suckers 0.130- 0.170 mm., breadth of same Q.170-0.190 mm. No fifth sucker, no vestige of same. Neck slender, 2.0-3.0 mm. long by 0.1-0.2 mm. broad. First proglottids broader than long, 0.255 mm. broad by 0.017-0.020 mm. long. Mature proglottids as much as 0.85 mm. broad by 0.34-0.37 mm. long. Ripe proglottids longer than broad or quadrate 0.680 mm. broad by 0.90-1.00 mm. long. Old spent proglottids up to 2.0 mm. long by 0.4 mm. broad. Segmentation evident. Posterior angles of proglottids slightly projecting. No genital papilla. Genital pore marginal, irregularly alternating, situated at end of first i/4-% of proglottid. Testes numerous, 75-80 or 90, in a single layer occupying entire field between vitellaria anterior to ovary. Breadth of testes 0.4-0.6 mm., length of same 0.07-0.10 mm. Vas deferens a large mass of coils in the mid-field. Ductus ejaculato- rius with few or no coils. Cirrus slender, straight, muscular. Cirrus- pouch slender, nearly straight, muscular, 0.185-0.20-0.265 mm. long. Length of cirrus-pouch 21^-3 times into proglottid width. 157] PROTEOCEPHALIDAE—LA RUE 157 Vagina always anterior to cirrus-pouch, never crossing the latter. Beginning region of vagina narrow. This region about 0.1 mm. long, terminated by weak sphincter vaginae. Adjacent to narrow region a dilated portion. Vagina not ciliated in any part of length. Vesicula seminalis present. Vitellaria with large follicles, not paralleling pos- terior margin of proglottid. Uterus when fully developed with 20-25 lateral outpocketings on either side. ^ Uterine pores ventral, 2-3-4 in number. Eggs with three membranes. Embryos 0.014-0.0156-0.0168 mm., second membrane 0.026-0.031 mm., outer membrane 0.027-0.033 mm. in diameter. Excretory system has four main lateral trunks. Ventral vessels large, dorsal vessels much smaller. All main vessels sinuous or spiral. Many secondary openings to exterior. Habitat: In intestine of Lepisosteus platostomus (type host), Illi- nois river, Havana, Illinois (type locality). Type: Alcoholics No. Ha 30 i and slides from same. Cotypes, Ha 12 d, e ; Ha 29 f ; Ha 87 a ; Ha 88 a ; Ha 101b ; Ha 110c. Mate- rial in Dr. H. B. "Ward's collection. La Rue (1911:479) in a preliminary way described this species. In a collection of endoparasites secured by Dr. H. B. Ward from fish caught in the Illinois river at Havana, Illinois, were some speci- mens of Proteocephalus somewhat resembling the species which the writer (1911) has designated as P. perplexus. On account of the pecu- liar form of the head and suckers of this species the name Proteoceph- alus singularis La Rue has been proposed for it. In all, eight gars were examined. Of this number only one was uninfested with this parasite. This gar was infested only with P. perplexus. The numbers of P. sin- gularis present in each of the seven infected hosts were : 2, 7, 26, 2, 5, 4, 8. Two gars had a mixed infection of P. singularis and P. perplexus. Slides have been prepared from some of this material. Its study showed that the longest piece measured 170 mm. Com- plete strobilas perhaps measure up to 250 mm. or more. Its maximum breadth is about 0.90-1.00 mm. The strobila is slightly smaller than that of P. perplexus yet it greatly resembles the latter species in out- ward appearance. The more slender neck and the smaller head are its more readily noted points of difference. The head (Figs. 24, 25) is small, measuring from 0.250 to nearly 0.300 mm. in breadth by 0.20- 0.22 in length. At its broadest part it bears four large suckers which when well expanded cover up nearly the whole surface of the head except the apical region. The apical region in most species is flattened or conical, but in this species it is drawn out into a long slender pro- tuberance which has no hooks. This is not a rostellum. At times this 158 ILLINOIS BIOLOGICAL MONOGRAPHS [158 protuberance is greatly contracted. Between the suckers are deep grooves which in many cases cause the head to appear almost lobate. The suckers themselves are more or less variable in shape but they always show the pointed apex. The cavity is shallow, the muscular wall thin. The suckers measure 0.130-0.170 mm. long by 0.170-0.190 nmi. broad. A fifth sucker is not present. A careful search through three series of sections has failed to reveal any trace of an endorgan. The neck is long and slender, 2.0-3.0 mm. to the first traces of segmenta- tion. The breadth is 0.1-0.2 mm., usually much narrower than the head. The neck grades over almost imperceptibly into the first proglottids which are very difficult to discern. The first proglottids are 12-15 times broader than long, being about 0.255 mm. broad by 0.017-0.020 mm. long. As the proglottids near maturity they increase greatly in size measuring up to 0.85 mm. broad by 0.34-0.37 mm. long. Proglottids in which the uterus contains some eggs measure 0.51 mm. long by 0.867 mm. broad or are even quadrate, each dimension being about 0.85 mm. The ripest proglottids become longer than broad, measuring 0.680 mm. broad by 0.90-1.00 mm. long and in rare cases of old spent proglottids the length may be about 2.0 mm. and the breadth about 0.4 mm. Segmentation is evident. No lon- gitudinal furrows are present. Transverse furrows occur only at the division lines between the segments. The posterior angles of the pro- glottids project slightly beyond the anterior margin of the proglottid following. This species has not been thoroly investigated as to its histological structure. However, certain points have been worked out with some care. The cuticula, the.subcuticula, the parenchyma, the muscles of the strobila, and the nervous system were not seen to differ essentially from similar structures in P. amhloplitis. The muscles of the head were worked out in series of transverse and frontal sections. The muscles of the apical protuberance of the head could not be worked out with care but that region could be seen to be well supplied with muscles especially in the subcuticular layer. The peripheral parts of the apical region of the head contain many heavy muscles going up toward the tip. In the middle and lower region of the suckers about 0.135 mm. from the tip of the head heavj- muscles cross from one sucker wall to the wall of the sucker opposite forming a heavy muscle cross (Fig. 40). Weaker muscles cross the head dorso- ventrally and laterally. These muscles extend to the subcuticular re- gion and serve by their contraction to cause in part the deep grooves between the suckers. Near the upper limits of the suckers at a depth of about 0.10 mm. from the tip of the head heavy muscles (Fig. 39) 159] PROTEOCEPHALIDAE—LA RUE 159 connect the sucker wall with the lateral or dorso-ventral surfaces of the head. These probably serve a double function of causing by their con- traction the deep grooves between the suckers and of pulling the adja- cent margins of the suckers together, thus broadly flaring the sucker. In this region the muscle-cross is weakly developed. In the lower part of the head (Fig. 41) just as the suckers disappear from transverse sections the fibers of the muscle-cross flare out to secure a broad attach- ment on the sucker wall. In fact a great many fibers dip down below and attach themselves near the lower outer margin of the sucker. At the sides of each sucker large groups of very heavy muscles may be found the attachments and courses of which are best made out in lon- gitudinal sections. Transverse fibers, i. e. lateral and dorsoventral, pass through the muscle-cross and assist in the formation of a muscle-star (Fig. 41). Below this point the muscles rapidly assume the relations of the muscles in the strobila. The longitudinal muscles of the head are fairly well worked out. Certain groups which were of undetermined character in transverse sections can be readily distinguished in frontal sections. The large groups of tangentially cut ends (Fig. 41) at either side of the sucker are in reality longitudinal muscles which come up from the neck region and find their attachment on either side of the sucker (Fig. 87), right and left. Much weaker muscle bands pass up toward the tip of the scolex. In the apical region (,Fig. 86) many heavy muscles attached to the sucker wall pass out by diverging paths to the subcuticular area. These probably control not only a certain part of the movement of the suckers but also the form of the apex. The muscles of the head, both longitudinal and transverse, are much more strongly developed than in the head of P. flaroides, which the writer has worked out with great care (La Rue 1910). Their arrangement in the two forms is very similar, tho certain groups of muscles present in P. singularis are lack- ing in P. filaroides. In the head the excretory vessel may be followed as coiling and anastomosing trunks and vessels which are much less developed than in P. amhloplitis or P. perplexus. In the neck region the anastomoses of the excretory system are much like those in the head. Here four main lat- eral vessels are to be found with branches which have a very few openings to the exterior. A little further posteriad the excretory ves- sels increase in size. This is particularly true of the ventral vessel. Both ventral and dorsal vessels Jiave a very sinuous or spiral course even in the most elongated proglottids. In frontal sections (Fig. 83) the sinuous ventral vessels appear as series of oval or circular spaces in the parenchyma. In either frontal or transverse sections the ventral 160 ILLINOIS BIOLOGICAL MONOGRAPHS [160 vessel is very prominent on aeeoimt of its very large lumen. At fre- quent intervals branches may be seen to be given off from the ventral vessel and a lesser number from the dorsal. Many of the ventral branches communicate to the exterior by means of small ducts through the cuticula. These branches are more numerous and more prominent than in any other Proteocephalid examined by the writer. One branch opens quite regularly at the posterior angle of the proglottid. Other branches (by far the largest number) open on the ventral surface. A few branches of the ventral vessel open on the dorsal surface. No duct connecting the ventral excretory ducts in the posterior part of the pro- glottids has been observed, nor have the relations of the excretory vessels been observed in the end-proglottid. There is no genital papilla. The genital pore is marginal, irregu- larly alternating, and situated at the end of the first third or two-fifths of the proglottid. Vagina and cirrus open into the common genital sinus, the vagina always anterior to the cirrus. In all the general features of the sexual organs these are typical of the genus. The testes are ovoidal or spheroidal in shape, 0.04-0.06 mm. broad by 0.07-0.10 mm. long. They are arranged (Fig. 85) in a single layer which fills the dorsal region between the vitellaria anterior to the ovaries. The region in which the coils of the vas deferens lie is free from them. They are 75 to 85-90 in number. The vasa efferentia can very readily be made out just below the layer of longitudinal muscles of the dorsal side. These empty into the vas deferens which makes a large mass of coils in the middle of the proglottid and reaching over to the cirrus-pouch. This knot is relatively thick for it extends from dorsal to ventral wall of the dermo-muscular sac* Entering the cirrus-pouch (Fig. 84) the vas deferens which now becomes the ductus ejaculatorius passes over almost immediately into the straight cirrus. The ductus ejaculatorius is usually straight but sometimes it is thrown into from one to three small coils. The cirrus itself has not been seen protruded. It is always slender, straight, and muscular. The cirrus-pouch (Fig. 84) is slender, nearly straight, and quite muscular. It measures 0.185-0.200-0.265 mm. long. Its length goes 21/^-3 times into the proglottid width. The vagina (Fig. 84) in its first part has a narrow lumen. This region extends about 0.100-0.110 mm. from the vaginal opening. It is characterized by its rich covering of gland cells and its weak longitudi- nal and circular muscles. The vaginal sphincter which is poorly devel- oped is situated just at the end of this first region. The sphincter is about 0.025 mm. long. Immediately following this region with the narrow lumen is a dilated portion which may extend clear to the vesic- ula seminalis. There is no ciliated region of the vagina. The vagina 161] PROTEOCEPHALIDAE—LA RUE 161 does not cross the cirrus-pouch but lies anterior thereto until it comes to the knot of the vas deferens which it passes ventrally. It forms no coils anterior to the ovary but may be somewhat sinuous. The vitellaria (Fig. 85) are lateral. The follicles are large, and closely packed to- gether. In the posterior part of the segment the vitellaria never extend posterior to the ovary as in P. perplexus. The vitelline ducts are as in P. amhloplitis. The lobes of the ovary are smaller than in P. perplexus or P. amhloplitis. They are more branched than in either of those spe- cies but this branched condition cannot be determined except in sections. The relations of the oocapt, ootype, oviduct, lower vagina, vitelline ducts, and uterine passage are typical of the genus and need no expla- nation here. The uterus is a median tube in mature proglottids. In ripe proglottids (Fig. 83) the median tube has 20-25 lateral outpocket- ings on either side which take up the entire ventral field of the segment bounded by the anterior and posterior margins and by the ventral excretory ducts. Two, three or four ventral uterine pores have been observed, tho in most of the very old proglottids the ventral body wall is split from end to end. The formation of the ventral uterine openings is as La Eue (1909) described the process in 0. filaroides. The eggs very much resemble those of P. perplexus in size but differ in having a thinner and more hyaline middle membrane which is never split into two layers. The embryos measure 0,014-0.0156-0.0168 mm. The second membrane measures 0.026-0.031 mm. and the other hyaline membrane 0.027-0.033 mm. This species in the structure of the head stands quite by itself. Its proglottids somewhat resemble those of P. perplexus but are smaller. In toto preparations the ventral excretory ducts of P. singularis being much larger make a fairly easy means of separation. In the number of uterine pouches the two species are much alike, but these pouches in P. perplexus extend farther laterad than in P. singularis. In the posi- tion of the vaginal sphincter the two species are much alike but the beginning region of one is dilated, in the other contracted. One has a ciliated vagina, the other not. The cirrus-pouch of P. singularis is more slender, the cirrus and ductus ejaculatorius are straighter and more slender than in P. perplexus. 152 ILLINOIS BIOLOGICAL MONOGRAPHS [162 PROTEOCEPHALUS SULCATUS (Klaptocz) [Figs. 130, 131, 175, 176] 1906: Ichthyotaenia sulcata Klaptocz 1906:123-130 1911: Proteocephalus sulcatus La Rue 1911:475 Specific Diagnosis: The characters of the genus. Cestodes of small size, up to 68 mm. long. Maximum breadth 1.5-2.0 mm. Scolex very variable in form, unarmed, without apical depression or fifth sucker, divided by distinct furrows into four quadrants. Median fur- rows arise near first proglottids. Cross-section of one type of scolex nearly round, of the other elliptical. Breadth of scolex 0.46-1.75 mm., thickness of same 0.67-1.28 mm. depending on contraction states. Suck- ers, deep rounded, one in each quadrant. Diameter of sucker 0.250 mm. Neck none. First proglottids broader than long. Mature and ripe pro- glottids quadrate or longer than broad. Last proglottid rounded pos- teriorly. Maximum breadth of proglottid 1.5 mm., maximum length of same 2.0 mm. Grenital pore at end of first third of segment. Cirrus-pouch about 0.20-0.25 mm. long, extending about i/4 across the proglottid. Several coils of ductus ejaculatorius in cirrus-pouch. Cirrus when protruded long and slender. Testes about 200, irregularly arranged between vitel- laria. Opening of vagina posterior to the cirrus-pouch. Lumen of vagina large. Ovary posterior, bUobed. Vitellaria follicular, lateral. Uterus with 10-12 lateral out-pocketings in ripe proglottids. Eggs pear-shaped, circular in cross-section. Diameter of same 0.016 mm, length up to 0.019 mm. Habitat: Polypterus endlicheri Heckel (type host), taken at Duem (tj^pe locality) on the White Nile, and Clarotes laticeps Riippell, from the White Nile in the region of Khartoum. The material was collected by Dr. F. Werner in the spring of 1905, was described by Klaptocz (1906), and was listed by La Rue (1911) among other species of Proteocephalus. In the summary and also in the following description the data are taken from Klaptocz 's paper and from his drawings. A specimen from Clarotes measured 68 mm., one from Polypterus 60 mm. The scolex (Figs. 130, 131) is of very variable form, is un- armed, has no apical depression, and it always shows four very distinct furrows of which the two on the median line are the heavier. These divide the anterior face of the scolex into four large similar quadrants whose acute angles come together at the tip of the scolex. The free 163] PROTEOCEPHALIDAE—LA RUE 163 margins of the quadrants often are indented especially on the flattened sides. The furrows, especially the heavier median ones, arise in the region of the first proglottids. In each quadrant a deep rounded sucker is sunken which lies nearer the margin of the scolex than to its tip. Two types of scolex are recognized with intermediate forms. The one is more or less flattened on the anterior face. It has a more or less round cross section. Its furrows are shallow, and its suckers are di- rected anteriad while the other type has an elliptical transverse section. Its thickness is less than the breadth of the scolex. The scolex itself is much flattened. The furrows are deep and very plain, reaching nearly to the tip of the scolex. The suckers are more elongated and the sucker openings are directed outward. These types of head are to be consid- ered contraction states of the same species since intermediate stages are present. The second type is found in Polypterus, and the first type in Clarotes. The diameter of the scolex in specimens from Clarotes lati- ceps ranges up to 1.72 mm, the diameter of a sucker of the same 0.250 mm. The diameter of the smallest scolex of this host is 0.75 mm. The thickness of scolices from Polypterus endlicheri ranges from 0.67 to 1.28 mm., the breadth from 0.46 to 0.675 mm. No neck is present. The young- est proglottids are thinner than the head and only slightly narrower. Their breadth exceeds their length. Proglottids increase in both breadth and length with age until they are quadrate in form or longer than broad. The last proglottid is rounded posteriorly. The maximum breadth of a proglottid from Clarotes is 1.5 mm, maximum length 2.0 mm. The maximum breadth of a segment from Polypterus is 1.5 mm. and the maximum length of the same 1.9 mm. Sexual ripeness appears very early. The anlagen of genital organs in stained specimens may be seen in very young proglottids within two scolex lengths of the head. Many proglottids are sexually ripe before becoming quadrate in form. The marginal genital pore alternates irreg- ularly. Sometimes in as many as ten to twelve or more proglottids the genital sinus may be on the same side tho this condition is rarely true in more than five segments. The sinus (Fig. 176) is situated at about the end of the first third of the segment. The vagina opens posterior to the cirrus-pouch. The cirrus-sheath (Fig, 176) containing the coiled cirrus (or cirrus plus the ductus ejaculatorius) has a pear-shaped form and lies perpendicular to the margin of the proglottid. It may extend 14 across the breadth of the proglottid. The cirrus-pouch is about 0.20- 0,25 mm, long (measured from Klaptocz's figures which are drawn to scale). The cirrus (Fig, 176) when protruded is very long and slender. It is thicker at the base than at the point and is devoid of hooks or bristles. The testes are elliptical, in number about 200. The testicular 164 ILLINOIS BIOLOGICAL MONOGRAPHS [164 field is limited by the -vitellaria, the anterior margin of the segment and the ovaries. There is no median zone free from them except where they are pushed aside by the developing uterus. As the uterus con- tinues to develop the testes are pushed well into the lateral fields. The vagina (Fig. 176) which has a large lumen runs to the middle of the proglottid in a more or less sinuous course, then bends and passes directly back to the posterior end of the segment. In proglottids with developed uterus the vagina is pushed somewhat from the median line and, it seems, always toward the side on which it opens. The ovary is posterior, is bilobed, and the lobes are limited laterally by the vitellaria. In the end-proglottid the lobes of the ovary are bent together. The vitellaria are follicular and lateral. On the porose side the vitellaria is divided into two parts connected by small follicles which lie dorsal and ventral to the genital passages. The uterus (Figs. 175, 176) is a median tube reaching to the anterior end of the proglottid from which arise many (10-12 in drawing) lateral outpocketings. These are separated when fully developed by thin tissue-layers. The eggs are pear-shaped, circular in cross-section, 0.016 mm. in diameter and 0.029 mm. long. Despite the fact that Klaptocz found an apparently intergrading series between the types of head mentioned by him it seems to the writer that there is a possibility of his having confused two forms of very similar appearance. The writer in the present work on Proteo- cephalus perplexus and P. amhloplitis found considerable difficulty in distinguishing the heads. And in certain respects the structure of the internal organs of the proglottids was remarkably similar. So too it was found to be difficult to distinguish the proglottids of P. perplexus and P. singularis. This was made especially difficult when both species occurred in a specimen of Lepisosieus platostomus. The fact that this species seems to occur in two such widely separated families of fish is a further intimation that two species of parasite are here included under the one name. Material from the two hosts should be carefully reworked. 165] PROTEOCEPHALIDAE—LA RUE 165 PROTEOCEPHALUS PENTASTOMA (Klaptocz) [Figs. 126-129] 1906: Ichthyotaenia pentastoma Klaptocz 1906:130-133 1911 : Proteocephalus pentastomus La Rue 1911 :475 Specific Diagnosis: Characters of the genus. Cestodes of small size. Strobila up to 28 mm. long; maximum breadth of same 1.19 mm. Neck none. First proglottids many times broader than long. Mid- proglottids 1.19 mm. broad, 0.21 mm. long. Sixth from last pro- glottid 0.59 mm. broad, 0.21 mm. long. Head large, oval in cross- section, 0.975 mm. broad by 0.83 mm. thick. No rostellum, no hooks. Four large suckers, oval or round in outline, 0.50 mm. in diameter, situated in four quadrants. Suckers separated from each other by longitudinal furrows. A true fifth sucker 0.085-0.100 mm. in diameter situated at apex of head. Genital aperture about middle of proglottid. Vagina posterior to the cirrus-pouch. Testes 70-100, arranged irregu- larly between vitellaria with tendency toward formation of two lateral fields. No data on cirrus-pouch and vas deferens. Vitellaria lateral, not voluminous. Ovary bilobed, posterior. Uterus immature. Habitat : Polypterus hichir Geoffr., White Nile near Khor Attar. Klaptocz (1906) described this species and it has not since been described from the specimens. La Rue (1911:475) gave it a place in a list of species of Proteocephalus. A single specimen was taken by Dr. F. "Werner, Feb. 16, 1905, while making a journey up the Nile river into the Sudan. All data are taken from Klaptocz 's (1906) paper since it was impossible to secure any material for the writer's examination. Measurements of the worm are as follows : Total length 28.0 mm. ; lateral diameter of scolex 0.975 mm., dorso-ventral diameter 0.83 mm. ; maximum diameter of suckers 0.5 mm.; diameter of fifth sucker 0.085- 0.10 mm. ; thickness of proglottids near scolex 0.46 mm., breadth 0.87 mm., length 0.04 mm.; maximum breadth of proglottid near middle of the strobila 1.19 mm., length 0.21 mm.; breadth of sixth proglottid from end 0.59 mm., length 0.21 mm. ; breadth of next to last proglottid 0.41 mm., length 0.31 mm. ; breadth of last proglottid 0.33 mm., length 0.51 mm. The scolex (Figs. 126, 127) is somewhat oval in transection, surpassing the breadth of the first proglottids. It possesses no rostellum, no armature of hooks, but has an apical sucker 0.085-0.100 mm. in diameter. The four equal sized suckers of somewhat oval or round shape vary in size in different individuals. They are about 0.50 mm. in 166 ILLINOIS BIOLOGICAL MONOGRAPHS [166 diameter and are situated on the four quadrants of the head. The four quadrants are somewhat swollen and are separated from each other by longitudinal furrows. The apical depression is a true sucker, as is shown in the stained specimen. There is no neck, the first segments appearing under the microscope 0.060 mm. behind the margin of the suckers. The size relations of the proglottids have already been given. From the drawing, reproduced (Figs. 128, 129), the strobilation is evident, the posterior angles of the proglottids being quite prominent. The anlagen of the sexual organs may be seen 7 mm. back of the tip of the scolex while the well developed testes may be seen 3 mm. farther posteriad. These are elliptical in shape, their long axis lying in the long axis of the worm. They number 70-100, and lie irregularly scat- tered between the vitellaria and anterior to the ovaries. They are most numerous in the lateral fields but they may also occur in the median part especially in the anterior region. No data are given concerning the cirrus-pouch and the vas deferens. The genital pore is irregularly alternating. It is situated near the middle of the margin of the seg- ment, but in the last proglottids a trifle anterior thereto. The vagina opens posterior to the cirrus-pouch. Just before its opening it possesses a considerable broadening, the diameter of which is about equal to the broadest diameter of the cirrus-pouch. On either side of this broadened part the vagina is narrow. The vitellaria are lateral longitudinal glands which develop late. They are not volum- inous. The bi-lobed ovary lies in the posterior part of the proglottid as in Proteocephalids. Since the uterus was inunature in this species the eggs could not be observed. This species easily separates itself from the most of the forms, parasitic in fish, by reason of the large size of its head and suckers. The position of the vagina posterior to the cirrus-pouch is a further diagnostic character of value, while the lack of an unsegmented neck and the proportions of the proglottids are characters which serve for its identification. Unfortunately Klaptocz failed to describe and to figure the cirrus-pouch, cirrus, and vas deferens which are of great value in making a positive determination. The uterus being immature could not be described. For these reasons this species which probably is a species of Proteocephalus cannot be accurately placed in its relation to the other members of the genus. 167] PROTEOCEPHALIDAE—LA RUE 167 PROTEOCEPHALUS FOSSATUS (Riggenbach) [Figs. 133, 180] 1896: Ichthyotaenia fossata Riggenbach 1896:166-193 1911 : Proteocephalus fossatus La Rue 1911 :475 Specific Diagnosis: The characters of the genus. Cestodes of short length, 3.5-4 cm. long. Scolex large, visible to nailed eye, maximum breadtli of same 0.714 mm. Anterior end of scolex conical, bearing at apex a slight concavity, not a fifth suclier. Sucliers, round, 0.34 mm. in diameter, borne at broadest part of head. Neck broad, 0.85 mm. long. First proglottids broader than long, 0.612 mm. broad by 0.135 mm. long. Mature and ripe proglottids, quadrate to longer than broad, End- proglottids not observed. Lateral margins of proglottids quite straight^ about the genital sinus a slight elevation or genital papilla. Genital aperture marginal, irregularly alternating, situated a little anterior to the middle of the proglottid. Testes, numerous, 120-150, in medullary parenchyma between vitellaria. Vas deferens, a loose mass of coils between cirrus-pouch and middle of proglottid. Ductus ejacu- latorius with few coils. Cirrus short and thicl^. Cirrus-pouch pear- shaped, 0.30 mm. long, extending about y^ across the proglottid breadth. Vagina, opening anterior to cirrus-pouch. Vaginal sphincter small, near opening. Lumen of first part of vagina broad, nearly as large as cirrus-pouch. No coils in vagina anterior to ovary. Arrangement of organs in interovarial space typical of genus. Ovary bilobed, posterior. Vitelline glands follicular, lateral, extending full length of segment. Uterus in ripe proglottid with many lateral outpocketings on either side. Eggs, round, thin shelled structures, size not given. Habitat : Intestine of Pimelodus pati Valenc, Rio Paraguay, South America. This species was described by Riggenbach (1896) who made it a member of the genus Ichthyotaenia. La Rue (1911) listed this species in a list of species of Proteocephalus. The material was collected by Dr. Ternetz in January and February 1894. The following description is based on Riggenbach 's (1896) paper. The worms as collected were of small size, 3.5-4.0 cms. long. There was no undamaged strobila. The neck is 0.85 mm. long and is quite broad. It passes imperceptibly into the youngest proglottids. The scolex (Fig. 133) is relatively large, and is perceptible to the naked eye. It bears four large suckers at its broadest zone. Here the scolex is 0.714 mm. broad. From this point the scolex becomes smaller toward the 168 ILLINOIS BIOLOGICAL MONOGRAPHS [168 end and also toward the neck. Its anterior region is conical. At the apex of the head is a slight depression which structurally is not a fifth sucker. There is no rostellum. The suckers are round in outline and they measure 0.34 mm. in diameter. The youngest proglottids in the proliferation zone are narrow trans- verse bands 0.135 mm. long by 0.612 mm. broad. With increasing age the proglottids elongate until mature and ripe proglottids may be quad- rate and the oldest proglottids even longer than broad. An end-proglot- tid was not seen. The margins of the segments are nearly straight. At the place of the opening of the genital passages the surface is slightly raised to form a small genital papilla. In the head the excretory vessels run close together. Near the suckers a circular anastomosis unites the vessels. In the space between the suckers is a complicated plexus. The two pairs of main lateral excretory vessels run through the length of the worm in nearly a straight course. In the posterior margin of each proglottid is a transverse anas- tomosis connecting the main vessels. In this region also and in the neck short ducts arise from the main ventral vessels only and pass to the exterior, opening on the surface near the posterior angle of the proglottid. The lumen of such ducts becomes smaller near the periph- ery of the work. The passage through the cuticula is quite small. The genital aperture is marginal, irregularly alternating, situated a little anterior to the middle of the proglottid. A very small genital papilla is present, due largely to a thickening of the margin of the sinus. The anlagen of the genital organs appear in about the twentieth segment. The testes (Fig. 180) number 120-150 and are relatively small, 0.5 mm. in diameter, round or polygonal in outline. They fill the whole field between the two vitelline glands and the anterior and posterior margins of the proglottid. The vas deferens forms a loose mass of coils between the cirrus-pouch and the middle of the proglottid. The mass lies posteriad to the cirrus-pouch and is excentric to it, lying on the porose side of the proglottid. In the cirrus-pouch the ductus ejaculatorius forms a few coils and then it passes over into the cirrus. The cirrus is enlarged into a thick vesicle which fills up nearly the outer half of the cirrus-pouch. The cirrus-pouch, which is about 0.30 mm. long, reaches about J^ across the proglottid breadth. It is an elongated oval in shape. The vagina which always opens anterior to the cirrus-pouch has a small sphincter near its opening. Further within, the lumen of the vagina enlarges into an ovoidal vesicle which may be almost as volumi- nous and as long as the cirrus-pouch. The vagina forms no coils ante- rior to the ovary. Riggenbach found no receptaculum seminis but he 169] PROTEOCEPHALIDAE—LA RUE 169 found a widening of the vagina anterior to the ovary. The two dilata- tions of the vagina take the place of the receptaculum seminis. The arrangement of the organs in the interovarial space is typical of the genus. The ovary is a bilobed structure, situated in the posterior part of the proglottid. The ovary does not seem to be made up of blind- pouches, as is true in the ovaries of most of the Taenias. Its outline is somewhat irregular, due to the sack-like processes which may be seen on the plump mass of the lobe. These extend posteriad nearly to the proglottid margin and laterally to the excretory vessels. The vitellaria as in all Proteocephalids are made up of a large number of single folli- cles arranged in long bands extending the full length of each lateral field of proglottid. The vitelline ducts arise in the posterior region of the segment and their course to the interovarial space is like that of other Proteocephalids. The shell-gland is poorly developed. The ute- rus lies in the middle of the proglottid and "As a canal with numerous lateral branches it extends itself through the whole proglottid." "The uterine eggs are round thin shelled structures." Their size was not given. This species is readily separated from a large number of species of Proteocephalus on account of its lack of a fifth sucker. Among those species which do not possess fifth suckers this species is most like P. sulcatus which likewise occurs in one of the Siluridae. The latter spe- cies however is much larger as to head and as to observed length. It also has a much larger number of testes. The form of the head is also different. PROTEOCEPHALUS SKORIKOWI (Von Linstow) [Figs. 152, 177] 1904: Ichthyotaenia skorikowi von Linstow 1904:18-19 1911: Proteocephalus skorikowi La Rue 1911:475 This species was described by von Linstow (1904). La Rue (1911) listed it among other species of Proteocephalus. The following descrip- tion is an abstract from von Linstow 's account. The length measures as much as 200 mm., the breadth anteriorly 1.14 mm. First proglottids beginning directly behind the scolex are very short. Breadth in middle is 3.75 mm; the length of proglottids here 0.95 mm. Breadth at posterior end equals 3.16 ram; length of proglottids here 1.97 mm. The last proglottid is rounded posteriorly. The scolex is short, 0.67 mm. broad. Von Linstow 's drawing of the head is reproduced (Fig. 152). Suckers measure 0.250 mm. in diameter 170 ILLINOIS BIOLOGICAL MONOGRAPHS [170 while a fifth apical sucker is 0,130 mm. in diameter. Muscles of sub- cuticular layer are as usual. The heavy layer of longitudinal muscles below the subcuticula in the anterior part of the worm is very strongly developed, filling up almost the entire space in unripe proglottids. Dorsoventral muscles are very heavily developed. In anterior segments the main longitudinal nerves lie about ^Vioo> and in ripe segments about '/ioo> of the segment width from the lateral margins. Mesad of the nerve trunks lie the excretory ducts two on either side. Chalkbodies are lacking entirely. Sexual openings are marginal, irregularly alternating, posterior to the middle in each proglottid. The vagina lies anterior to the cirrus. The cirrus is cone-shaped, blunt at the tip, 0.141 mm. long. The point is 0.042 mm. broad. The cirrus-sheath extends Vq-Yq across the breadth of the proglottid. The vas deferens makes many coils before entering the cirrus-sheath. Testes are very numerous, 0.053-0.083 mm. in diam- eter. From von Linstow's figure one may conclude that there are about 70-100 testes. The vagina runs in a curve to the middle of the posterior region of the segment where it forms many coils anterior to the ovaries. These coils function as a receptaculum seminis. The ovary is made up of two groups of club-shaped bags which run parallel to the posterior margin of the proglottid. Anterior to its middle lies an oocapt. Vitel- laria are follicular, reaching on left and right the full length of the proglottid inside the longitudinal muscles. The uterus in the posterior part fills the whole space within the longitudinal muscle fibers and extends anteriad in round diverticula. In von Linstow's drawing which is reproduced (Fig. 177) there are 6-8 diverticula on either side. Eggs are globular, 0.027 mm. They have two membranes, the outer one very delicate and hyaline. The six-hooked embryo measures 0.021-0.023 mm. in diameter. Habitat: Intestine of Acipenser steUatus (t3T)e host); River Giirgen, Caspian Sea (type locality). Von Linstow failed to state who collected the specimens of this species and the abundance of their occurrence. This species is one of the more robust Proteocephalids and is thus distinguished from a large number of species of the genus. The fact that the vagina forms many coils anterior to the ovary and that the ovary consists of slender club-shaped bags separates it effectively from all other known species. The position of the genital pore posterior to the middle of the proglottid is a further distinguishing feature. In many respects this species most closely resembles P. fossatus (Riggen- bach). 171] PROTEOCEPHALIDAE—LA RUE 171 PROTEOCEPHALUS SAGITTUS (Grimm) (?)1819: Bothriocephalus barbatulae Rudolphi 1819 :144 (?)1850: Bothriocephalus harhatulae Diesing 1850 :608 1872: Taenia sagitta Grimm 1872 :240-243 1878: Taenia sagittata von Linstow 1878 :260 1891: Taenia sagittata Monticelli 1891 :169 1896: Ichthyotaenia sagittata Riggenbach 1896 :267 1909: Ichthyotaenia sagitta Liihe 1909 :33 1911: Proteocephalus sagittus La Rue 1911 :475 Specific Diagnosis: Strobila small, as much as 45 mm. long by 1 mm. broad. Head thick, ending in an unarmed point. Suckers four, in pairs on the basal part of the head. Suckers transversely elongated and heavily muscled. Neck as much as 12 mm. long by 0.5 mm. broad. (Probably many young proglottids were overlooked in this exception- ally long neck.) Proglottids few. Youngest proglottids about quad- rate, older ones longer. Last eight proglottids 1.4-1.5 mm. long by 1 mm. broad by 0.3 mm. thick. Last proglottid always rounded poste- riorly. Cirrus-pouch large and clubshaped. Cirrus quite thick. Uterus with uterine pouches, number unknown. Genital pore situated near middle of lateral margin of proglottid. Habitat: In intestine of Cdbitis harbatula (type host), Peters- burg (type locality) and Province of Novgorod. Grimm (1872:240-243) described some cestodes which he had col- lected from the intestines of Cohitis harhatula at Petersburg and in the province of Novgorod. These he named Taenia sagitta. He called at- tention to the fact that Rudolphi (1819:144) had proposed the name Bothriocephalus harhatulae for some cestodes from Cohitis harhatula. Rudolphi gave no diagnosis nor description hence it is not possible to determine the genus to which his specimens belonged. Grimm also called attention to Diesing's (1850:608) reference to Bothriocephalus harhatulae and that Diesing gave no description of the form. Von Linstow (1878:260) listed Taenia sagittata Grimm (for sagitta) as a parasite of Cohitis harhatula. Monticelli (1891:169) included Taenia sagittata (for sagitta) in a list of cestode species parasitic in fish. Rig- genbach (1896:267) included Ichthyotaenia sagittata (Grimm) in a list of Ichthyotaenia. Liihe (1909:33) gave a very short diagnosis of Ich- thyotaenia sagitta (Grimm) which he apparently derived from Grimm's (1872) paper. La Rue (1911:475) included this species in a list of Proteocephalus species. 172 ILLINOIS BIOLOGICAL MONOGRAPHS [172 Because of its inaccessibility to many scientific workers Grimm's entire description of this species is here quoted, and since the tables at the end of this section give the essential data no digest of his paper is given at the end of his description : \J "TAENIA SAGITTA. — Der beriihmte Helmintholog Rudolphi erwahnt in seinem Werk Entozoorum Synopsis S. 144 eines Bandwurmes, den er im Darme von Cobitis barbatula aufgefunden hat. Da er aber nur ein Fragment, nicht aber ein voiles Exemplar des Wurmes besass, so gab er auch keine eingehendere Be- schreibung dieser als neu von ihm erkannten Art, sondern stellte sie grade zu den Grubenkopfen und belegte sie mit dem Namen Bothriocephalus barbatulae. Dies- ing stellte diese Art in seinem Systema helminthum zu den Species dubiae und setzte zu den von Rudolphi gesagten nur noch hinzu, dass "Fragmenta acephala servantur im M. C. V." (Syst. helm. I. p. 608). Etwas umstandlicher spricht sich S. Leuckart aus iiber das Aussehen dieses Helminthen, indem er sagt, "an dem sehr kleinen kopflosen Stiicke, das ich sah, war nichts Ausgezeichnetes. Die Glieder langer als breit, oder vollkommen quadratisch. Keine deutlichen Ovarien" (Sig. Leuckart, Zoologische Bruchstiicke. I. p. 57). Das ist Alles, was wir von diesem Bandwurme kennen und deshalb wird wohl nicht uberflussig sein, wenn ich im fol- genden die Resultate meiner anatomischen Untersuchung kurz zusammen fassen werde, die ich an diesem Wurm unlangst angestellt habe. "Ich fand namlich hier, in Petersburg, und im Nowgorod'schen Gouverne- ment 3 erwachsene Exemplare des Wurms in Cobitis barbatula, nachdem ich einige Hunderte dieses so haufig in unseren kleineren Flussen vorkommenden Fischchens durchmustert hatte. Aus dem Gesagten geht schon hervor, dass dies ein sehr seltner Wurm sein muss. Hier muss ich noch bemerken, dass, dem Kopfe nach, dieser Wurm der Taenia filicollis Rud. nicht unahnlich ist, sich aber von ihr durch die langeren Glieder, wie wir es unten sehen werden, unterscheidet. "Die Lange des grossten Exemplares betrug 45 Mm. bei einer Breite von i Mm. Der Kopf ist verdickt und endigt mit einer Spitze die keine Hacken tragt; die 4 Saugnapfe liegen paarweise auf der Grundhalfte des Kopfes; sie sind etwas in die Quere verlangert und stark muskulos, weshalb der Wurm auch so fest an die Wande des Darms sich ansaugt, dass man beim Einsammeln sehr vorsichtig sein muss, wenn man nicht "Fragmenta acephala" erhalten will. Das zu seiner Basis verengte Kopfchen geht in den ziemlich diinnen Hals tiber, welcher ungefahr 12 Mm. lang und 0,5 Mm. breit ist. Hinter dem Halse fangt die Kette an, in der ich 23 einzelne Glieder gezahlt habe. Die ersten resp. jungsten Glieder sind fast vollkommen quadratisch ; weiterhin werden sie etwas langer, so dass die letzten acht Glieder 14 bis 1,5 Mm. lang sind; dabei betragt ihre Breite i Mm., bei einer Dicke von nur 1,3 Mm., so dass der Wurm vollkommen plattgedriickt erscheint. Das letzte Glied ist immer von hinten abgerundet Dies ist alles was wir an einem unladirten Exemplare zu sehen bekamen. "Wenn wir nun aber einzelne zuvor mit Carmin und Glycerin bearbeitete Glieder und diinne Querschnitte unter dem Mikroskop untersuchen, so iiberzeugen wir uns, dass der Bau der Korpermasse dieses Bandwurmes sich iiberhaupt durch 173] PROTEOCEPHALIDAE—LA RUE 173 nichts von dem Bau anderer Bandwiirmer unterscheidet. Wir finden hier wie auch bei Cyathocephalus truncatus, dass der Korper aus folgenden Elementen besteht : — aus der kornchenreichen Grundsubstanz, die von sich schlangelnden dorso-ventralen Muskelbundeln durchsetzt wird; einer Schicht Langen-muskeln und einer Schicht Quer — oder Ringmuskeln, einer Schicht feinkorniger Rinden- substanz, in der die Enden der dorso-ventralen Muskeln liegen, und endlich der sehr feiner ausseren Haut, die gar keine Muskeln besitzt. In der Langsaxe eines jeden reifen Gliedes liegt das centrale Rohr des Eierstocks, welcher aber manch- mal naher zur einen oder andern flachen Seite zu liegen kommt, wie man es auf den Querschnitten bemerkt. Von diesem Centralrohr verlaufen nach beiden Seiten zu unregelmassig gebogene und theils sich auch verzweigende Auslaufer, die in ihrer Lange mittelst der dorso-ventralen Muskeln erhalten werden. In der Mitte des Hauptrohres geht von ihm die Scheide ab, die, nachdem sie eine schwache Biegung gemacht hat, sich in der Mitte der seitlichen Oberfliiche des Gliedes nach aussen offnet; die Scheide ist ziemlich breit, so dass die Eier sie leicht passiren konnen. In dem von mir untersuchten Exemplare waren die Eier in der Mehrzahl der Glieder vollkommen reif ; — sie enthielten eine grob und — feinkornige Masse und waren mit einer ziemlich dicken Haut umgeben. Aber wie in diesen reifen Gliedern, so auch in den jiingern bin ich nicht im Stande gewesen die sog. Dotterstocke auf zufinden ; ob sie hier so f riih verschwinden, oder zu fein sind, weiss ich nicht; auf den Querschnitten sind sie aber nicht aufzufinden. "Gleich iiber der Scheide liegt und offnet sich nach aussen das mannliche Zeugungsorgan ; dasselbe besteht aus einem ziemlich grossen und kolbenf ormigen Cirrusbeutel, in dem der eingezogene Cirrus liegt; der Cirrus ist ziemlich dick und am Grunde dunner als am Ende; dessen Kanal ist durch den Cirrusbeutel zu sehen. In den Wanden des Cirrusbeutels trafen wir, wie immer, Langs — und Quermuskeln. Die Samendriisen waren nicht zu sehen. "Dies ist alles was ich von dem Bau des Bandwurmes erfahren konnte. Die Unvollkommenheit meiner Untersuchung wurde aber durch den Mangel an Mate- rial bedingt. Dennoch aber fiihle ich mich berechtigt zu sagen, dass auch dies Wenige geniigt, um dem beschriebenen Bandwurm seine natiirliche Stellung in der Reihe seines Gleichen anzuweisen und somit die Zahl der zweifelhaften Arten zu beschranken. "Noch muss ich hinzusetzen, dass aus dem Gesagten doch klar ist, dass ich wohl mich nicht irre, indem ich den von mir augefundenen Wurm als dem Both- riocephalus barbatulae Rud. identisch halte." While the foregoing description is sufficient to warrant the inclu- sion of this species in the genus Proteocephalus it is not sufficient to enab.e one to determine the relations of the species to the other mem- bers of the genus. In size the form resembles P. filicollis and P. agonis. For the present the species must be put in the list of incompletely described species. 174 ILLINOIS BIOLOGICAL MONOGRAPHS [174 PROTEOCEPHALUS SALVELINI (Linton) [Figs. 143, 144] 1897: Taenia salvelini Linton 1897:424 1911: Proteocephalus salvelini La Rue 1911:475 Linton (1897:424) described this species. La Rue (1911:475) in- cluded this form in a list of species of Proteocephalus. Linton's description reads: "TAENIA SALVELINI. Type.—l E 6 El E^o ~E .T3 . E Eg 03 •Si *0 1/5 1 is NO 2. 11 £e E o -H CM 3 m *? J3 — •* 'T'^ 6\o A CMO O. g i« o (^ g V w >, V ■o o u •^ •*" o X — o n M X » ««-l C o m E 2.^ « t E E-o n4 o-o 2dx ►Jc Eg &> 4) OQ :5eE E COOro >-!od rt ^0^0 S" .'2 §Eo2 J Ei« u " rtt: • ■5 ^ E o > c rt °"? E ^M wiid ^ S 5 d<'0 •o 60 ca c • J3 E e §5- -E •3E CO [192 E5 E . E ^E do OU IT) S -^ >n 00 V b S u °<= ^JH .5e 00 -M V l< C3 u T3-5 :2:Se ^^ E •a V T3 E u 'S . U V g C0 "3 J3 u x^ w Ben ^^4 ^ 0^ 60 J) 2 E« C 2 s E « E efl •^"S E H a; de •0 V -H ja CM j> u H E& E? s ^ rt 1 3. 60 0. E 00— e u 3 ** u E E •CQtf S «?3 *^ ^05 ■• « Vi U «> E .^ * E^o E §2 Ei: n c oE 2e dE £ E E^E E2.2 h'O •^ E Hi c S a. e« o HO ^d •0 U E b « «o >«• W — z <6o C M ^ ^ 0«*! 8 -a -« vC j: S"& 3 o-S a 1= 3 3 £« hi 11 a u 193] PROTEOCEPHALIDAE—LA RUE 193 •V 3 •B 'J S " O 3 •G a. E E »■ f- n i o.i: > u 'C u o o .2 o ■4' CQ 01 « at o 6 c »> o E to o E " u o J3 ti o 3 — o ->o d o -, u 4^ 4) b V fel V >> (« E H-l ■i^ E C 60 s <.s E E 60 O >• o z s E u^ E oq^ « 3 c c« HO o^ 00 o a> Ji E ^i c S IgE ^:wE ^5 is to ft o 2 n a O ? CD pqS E'Si •0 o •a ii oo d><6 •« V > u O §;& u O go ;^ E •r- 3 •i a f u n n 3 S o Q H H 2 M •- 3 ts 60 o H > 3 E °E- m CO go n So u d»i u e> ^ •= C.2 H CO EE •J D V E Eo i- 60 --a ^ '"rt O tn JSio- .- u _ .E-2 3« ° '"Co a. 2 (8 *c O M i"0 ...S V. C -" ■O to a 2 15 60 B -a 60 g caS E Wo. t; 0 B V E E 1c.S >9d :ssE ■"5 »i d u t^ «"« 1 ctf -5 q d w CM V o K u «-Se B O CD [194 pS NO t^ c>jq 9. J £i :? O 0. u B u B * ca B C J E y « a E c U ^ S * i^ '«^ ii o2 -2 E >>s S B ■« ««S9 ♦^ B S** E2-^ EaS-o 3-5 g O t- o B U <-> M B UXi vE >E ■13 E « 5; >iE^ «>: E s E E S» ^. E'" ^E' tuts E 5 is EE eg o liE oE E»< -a o ~ •B — : V B B ca c««n E2-: dEg" E^ . o B MOd <» S « E «^2E i2 I- . § E J>«E <5 c9"5 s-s i;Eg S°E cu E 2'E^ O E M J" o> — ■s . S « E? 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I SE 2 c« -eg Be 2® mm m u 'HO d"^ "".^- 00 2" o-O ^ ctf j^ E E -oES ii §° B-a*i o « • u rtE .y c« v E KE EE°« E E "Ol t E o o. .10 « _• T32; E vo . c 0.0 u E ■f u|q 0.(5 Bo 3 "a .2 E 5E u u u ^ AS 5 * «sj O ES?^- E d V ^ a a oE^ ss E-^ 2:s ::^E "S S o o 195] "^ ^ 3 - u c o (v PROTEOCEPHALIDAE Q6 5w- A < '•i M <4 8-S SS o V O O o *(« a ^ _c it j; '« 60 u u.i: 3 E c« « 3 W V) ex 5 c I s E a 1^! u vo mjsv (A o « o C 3 O 3 a o iS >> to In •B M 3 c« c> _»; Efc* c« "3) u o lO u V V E Anterior, end of c ally runs of pouch C CO o s c "9 /D AE—LA /?C7£ •o g Sa B E o o CO E^ ll u Ec E S§ C4 iv (5 H=3 v> ^ s 3 o S OB o E o c> 2«? 1 5 195 OE "E PE Bo HS •a g-o SEb s5e So u Eu J3ii 3 H-oO •*'*• .2 2 E c 2 S w ^ J3 E3 OE as a ^ ™ o> 53 J3 ^ Z 00 C (I.CL, '^* 00 voo 1^ o 2 2 ^ o. -S U 4 £ 4 K CJ3 (j u to a3 O o o d Q. 7 5 3 ce u ^ V. > V u o 8 b u'S «E •S " E 5 .E §a 5 S 5 *5 *** 196 M CM t: «0 J U CM ^ d -H cS e 'S O (1 n ><*o X ^ M» 60 3 S o a ^ o V rs a o w "2 E ^ ^ o E^ J3 \o . c (C E •o «> ^ V _ 3 3 ^C 5s K ?« Ctt c •*".- c o s -5 _o U 5^ E en E _*» J^; "9 g o. o u CO ro^ ILLINOIS BIOLOGICAL MONOGRAPHS . e [196 B"2 BS o c« . 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V 5 s ^ •l t * 3 00 .« 00 1 •0 V *» fc 3^ Q ^ a ■* 1/5 C/3 N^ o «J fv- -2 V (A »i;« < as Co £ 1:3 61 •o a. "1*5 E-w ^ ^ •5 fa U r; o H 2 o E 6E u » o U ^E .:^E QE e<=> C.2 rtoo-o H o Co J30 E6 u ** iJ E o V eg u o § 2g •2 o SO 3 u<«< ' at « O ES tcS- **^ U CB O ^ rt — >>g m S c « " 5 ot: a 3 u n .5e?§S 3 £ I i ^ CI EE J3 m ■i V V Si 0) « SUV Q H H 5 198 ILLINOIS BIOLOGICAL MONOGRAPHS [198 c o u .S K 9. a. pL. ^ w .5 J3 u iJ a. (/) 13 "^ E • o V 5 o C > E rt • E B B •» _ * 00 u I'd ^°" So. K S ^^ c ? O u E" to E ci E »« 01 E2 E-^ ,xE >o E E 2 Ei 2E 5a "t3 O "O CO "" « P e o '- 5 m-S to ■*-* So n -> g o g rt ^ d5^ s E^ E2 s « E o o E oE .13 E '^ il a X J3 tXl u E i- rt C E^ 4 E oE Sk'Se c E teoN ^EJo J- m" . Ooo -O «oE S aioE C X^o -• rt tx E 5^-E «-— 2 — c c'Oo o S rt — • E o ■^ h X «i EC •CO "O 3 go E o ai^Ei w en . 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B rt ox e.s — 00 O it .2o m2 en •— « E:2 •°12 <" O B 3 ^ U t.EE u 199] PROTEOCEPHALIDAE—LA RUE 199 » c o U (/3 S ^ i o © „ .9 o S, 'C A B «3oo E;2 ^ —< 0\ m E « Vi B 2 S O 3 SO 8"" J2 E .^ ^^ ro f*5 • vovo eg®® S .a ^ E a « m 3 V u Q H H S <« (5 u •^ OO —lO i! o o "? <;t3 o, «^ aE g Is > S V 1)13 g • Eg E9c>t; i>6 o « tH OT3.5 C fO g Se o S-o-S u ^0 r.- E u ^m / E 8ES rtvod o •50 tf) -^j- ^''^fi c •°"=>2 S® Eoo . 3 "So V. o .2 ^ >> X ^0 u Oj 'u E„| 3 E SJo.2 a V SB 3_ 8E->b§ 5 rtOC.2 ,. 2 4J >*< .<^ C rt c^ c > *i rt o rt 3^*" B £■5=5 „ g M55-?a^ 2? > >>t3 a. C -S •2 v," ft J3 n 3 ^ 3 «.t: ^•5 o u Mm 200 ILLINOIS BIOLOGICAL MONOGRAPHS [200 8 C > C o U E t^ u o ^ C ? o I E£^5^ U O On C ^ « B >^ d E eg tn E 10 ^ .-c "^ e 2 VC- 5 ° *«• ^ • a, v^ E E ii S B - U.2 o 1/3 w o 5- ON 4> •50. 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TS e: s "o 3 en 60-= V 60 cd .i: C o 4-* !►, 1 u M U2 c ^ 0) 4; *j ^ g g 1, 60 C S.O O U 3 £ 8 g .2 3 ^ i-j= ♦^ O V H E « a 3 « V P c „ Ot3 N *" S ^'m 'S g a^ •■ U . kl o o S" SJ3 ^ .}> •S-s E i-S > D W W «S "3 "** 202 ILLINOIS BIOLOGICAL MONOGRAPHS [202 o U •S a; S-2 -S "? tZ Sit S.S E «•? e:h Bci aS «5 ^M i K^ 5 -^ 5 E** C h u 3 5 "? I- CM u E o m S aEjj |x" "60E oojE •-] s >« -4^ K ^ U 11 s "O tC •?-S u to 3 "o JU ^ii^ E "w ^ E t/2 5 cE eg 3g 4) g o « « •o " ? o S '^ o c tfrt «E.Si: ^ ^-^ 60 rt «) c H l ^ o & i^ es CO u CO «»; -«£ CM^ a E o U • u c.a Men I 2: 4> U 2^ 60S « J3 > « O Oh o Ph C V 5 u V a U V a 3 o 5 c E K 2 ^ ,^ "w * C/3 2 « t4-l a |j a> > 3 ^^ u ^ a S o U Et) M V E u .« 3 V Q H 5 u .2 3 ■" o * a, ■50 OT3 N li H H 3-S t3 0) IS VM 204 ILLINOIS BIOLOGICAL MONOGRAPHS [204 OPHIOTAENIA PERSPICUA La Rue [Figs. 10, 102] 1911 : Ophiotaenia perspicua La Rue 1911 :480 Specific Diagnosis: Characters of the genus. Length up to 36.0 cm. Maximum breadth about 2.0 mm. Head conical, flattened, divided by grooves into four quadrants. Breadth of head 0.355-0.408 ,nm., thickness of head as much as 0.306 mm., length about 0.270 mm. Suck- ers four, circular, oval or at times somewhat triangular, 0.105-0,170 mm. in maximum dimension. Cavity of sucker 0.053-0.106 mm. in diameter. Neck long, 5-7 mm. in length by 0.170-0.425 mm. broad. First proglot- tids short. Mature proglottids quadrate, 2.0 mm. in length and breadth, or somewhat longer than broad. Ripe proglottids measure as much as 3.8 mm. long by 1.2 mm. broad. Segmentation indistinct. Proglottids attached by full width. Surface smooth. In life and when preserved in formol specimens somewhat translucent. Genital pore marginal, irregularly alternating, situated near middle or at end of first third of proglottid. Vagina anterior or posterior to cirrus-pouch. Testes 150-215, oval or polygonal, measuring up to 0.053- 0.106 mm., situated in two fields, Vas deferens in ripe proglottids a heavy mass of coils reaching from end of cirrus-pouch to the mid-field. Cirrus-pouch 0.255-0.320 mm. long by 0.080-0.090 mm, broad. Ratio of length of cirrus-pouch to proglottid breadth 1 :4 to 1 :3. Cirrus slender, about 0.20 mm. long when protruded. Vagina dUated in first part, not crossing cirrus-pouch. Sphincter vaginae and receptaculum seminis present. Lobes of ovary long, flattened, irregular in outline, made up of anastomosing tubules. Oocapt and ootype present, Vitellaria loose. Uterus when ripe with 20-30 lateral pouches on either side. Uterine pores not seen. Eggs provided with three membranes, outer one 0.045- 0.100 mm. in diameter. Embryos 0.018-0,021 mm. Habitat: Natrix (Nerodia) rhomhifer Hallowell, (type host); Havana, Illinois, (type locality). Type : Unaccessioned bottles in coll. La Rue, also bottle in Dr. H. B. "Ward's collection. Slides of same. The host, a very large female, was caught on the banks of the Illi- nois river at Havana, Illinois, and was examined for parasites July 9, 1910. From the intestine 57 cestodes and pieces were taken. Of these 42 pieces had heads attached. No strobilas were found with an end- proglottid. There were, however, a number of specimens with ripe pro- glottids. Because of their translucent appearance in life and when pre- 205] PROTEOCEPHALIDAE—LA RUE 205 served in formol the writer (1911) has proposed the specific name Ophiotaenia perspicua. Other specimens of this species were furnished the writer by Mr. Herman Douthitt from Natrix (Nerodia) rhombifer taken in Oklahoma, June, 1910. La Rue (1911 :480) described this species in a preliminary way and made it the type of his new genus Ophiotaenia. Two heads of the lot from Oklahoma measured respectively 0.374 mm. and 0.340 mm. broad by 0.27 mm. thick. The suckers measured 0.119 mm. long by 0.102 mm. broad. The neck was 0.272 mm. broad and several millimeters long. The longest worm was 135 mm. long by a maximum breadth of 1.19 mm. Specimens were mounted in toto and from them a positive determination was made. The longest specimen of the preserved type material measured 36.0 cm. in length by a maxi- mum breadth of 2.0 mm. The neck is long, slightly broader than the head and not easily distinguished from the segmented portion following. The first proglottids are very short. About 16.0 cm. from the head the proglottids are quadrate, length and breadth being about 2.0 mm. These proglottids are mature. At 26.0 cm. from the head the proglottids begin to increase in length and to decrease in breadth. The second from the last proglottid measures 3.8 mm. long by 1.2 mm. broad. These proglottids are ripe. An examination of other specimens of the lot shows a considerable variation in dimensions. Proglottids are attached by their full width. The margins of the strobila are smooth, almost without indentations at the junction of the proglottids. As a conse- quence the segmentation is indistinct so that without staining and clear- ing the proglottid limits are made out with difficulty even with a microscope. The proglottids are rectangular in shape, rarely oval. The surface of the worm is sometimes thrown into shallow longitudinal fur- rows. No transverse furrows are noted. In life and when preserved in formol the specimens are translucent from which character is derived the specific name. The head is somewhat conical in shape, slightly flattened dorso- ventrally and marked off into four quadrants by grooves which extend from the basal region to, or nearly to, the apex. Each quadrant bears at its thickest and broadest region a sucker which opens outward and slightly forward. The apex does not exhibit a circular depression or a fifth sucker. The head varies in breadth from 0.255 mm. to 0.408 mm. This dimension slightly exceeds the thickness and length. A head 0.357 broad measured 0.306 mm. in thickness, while a head 0.408 mm. broad was about 0.270 mm. long. The suckers show also considerable variation in size and shape. In general they are nearly round or oval in outline with shallow cavities. 206 ILLINOIS BIOLOGICAL MONOGRAPHS [206 However some of them appear nearly triangular. They measure 0.105- 0.170 mm. in diameter. In the smaller ones the effect of contraction is very plainly shown by the deeper cavity and by the thickened muscu- lar wall. The diameter of the sucker opening varies from 0.053 to 0.105 mm. A vestigial fifth sucker resembling that of 0. filaroides is found imbedded in the tissues of the head. The neck is always long, 5 to 7 mm., and its breadth is subject to considerable variation, from 0.170 to 0.425 mm. Since this study is based upon toto preparations almost exclusively, the excretory, nervous and muscular systems were not studied carefully. The excretory system is made up of coiling trunks and anastomosing branches in the head and extreme anterior neck region. In the pro- glottids two pairs of main lateral excretory vessels can be made out. The sexual organs (Fig. 102) in their character and relations are typical of the snake Proteocephalids. The genital sinus is marginal, irregularly alternating and situated near the middle, or it may be as far anterior as the end of the first % of the proglottid. It is marked by a slight elevation which becomes more pronounced in the more elon- gated proglottids. The vagina and cirrus open into the common shallow genital sinus. The vagina lies either anterior or posterior to the cirrus- pouch but more frequently anterior. Rarely the vagina is dorsal to the cirrus-sheath. The testes are very numerous, 150-215. They are arranged in two fields, leaving a free median zone. In elongated mature and ripe pro- glottids the testes are oval or even polygonal. They measure as much as 0.053 by 0.106 mm. It is to be noted that the testes tend to occur in groups of 2, 3 or 4. In these cases the limiting membranes of the testes touch each other. The vasa efferentia may be clearly seen in some toto preparations. They much resemble the vasa efferentia in other species. The vas deferens in young proglottids is nearly straight. It arises in the middle of the proglottid and extends to the cirrus-pouch which it enters. As the proglottid becomes older the vas deferens becomes longer and more and more coiled until in mature and ripe proglottids it forms a heavy mass of colls lying between the cirrus-pouch and the middle of the segment. When filled with deeply stained spermatozoa this mass becomes very prominent. Upon entering the cirrus-pouch the vas deferens becomes the ductus ejaculatorius, which is coiled several times before passing over into the heavier-walled cirrus. The cirrus is some- what swollen but is much smaller than in Crepidohothrium gerrardii, 0. calmettei, or 0. grandis. When protruded it is slender and of even diameter from tip to base. Its length protruded is about 0.200 mm. This measurement is taken from a specimen from Oklahoma. The 207] PROTEOCEPHALIDAE—LA RUE 207 cirrus-pouch is more slender than in several other species of Ophiotae- nia. In mature and ripe proglottids it measures from 0.255-0,320 mm. long by 0.08-0.09 mm. broad. In maturing proglottids it measures about 0.25 mm. long and is considerably narrower than in ripe ones. Its length goes into the proglottid breadth 3-4 times. In mature and ripe proglottids the vagina very near its opening to the exterior has a wide but short inflated region. A sphincter vaginae has been found. In this region the vagina is richly set with gland cells. In its course to the interovarial space the vagina bends somewhat anteriad and then inward and posteriad, crossing the numerous coils of the vas deferens but not crossing the cirrus-pouch. Just before the ovary is reached the vagina is somewhat twisted or even thrown into small coils. A small receptaculum seminis can be seen in some preparations. The ovarian lobes are long flattened bodies of irregular outline. They are not solid but are made up of short heavy anastomosing tubes of irregular shape. Just back of the mid-piece of the ovary the muscular oocapt can be noted even in toto mounts. The coils and connections of the oviduct, vitelline duct, uterine passage and lower vagina cannot be made out distinctly. An ootype and shell-gland have been seen in some prepara- tions. The vitellaria are loosely follicular and lateral. The paired vitel- line ducts cross the ovarian lobes. The uterus in maturing proglottids is a median tube from which as the proglottid becomes older lateral pouches arise by the method that has been described for 0. filaroides by La Rue (1909). There are 20-30 large pouches on either side and a number of smaller ones. No uterine pores have been seen. In one toto preparation the uterine passage may be traced to a point 0.29 mm. anterior to the mid-piece of the ovary where it discharges into the uterus. The eggs are furnished with three membranes, an outer one which is smooth, thin and hyaline, a middle membrane thick and granular, and an inner thin membrane surrounding the embryo. The outer spheroidal membrane measures 0.045-0.06-0,100 mm. and the embryos are 0.018-0.021 mm. in diameter. Plerocercoids were found encysted in the intestine and liver of the host caught at Havana, Illinois. This species is much smaller than Crepidohothrium gerrardii (Baird), 0. marenzelleri (Barrois), 0. calmettei (Barrois) and 0. tri- meresuri (Parona) in most respects tho it may exceed some of these in length. It most closely resembles 0. nattereri (Parona), likewise from one of the Colubrinae. It has a larger head and larger proglottids and a greater number of testes than 0, nattereri. 0. perspicua is much larger than 0. filaroides La Rue from Amhlystoma tigrinum Green, Its 208 ILLINOIS BIOLOGICAL MONOGRAPHS [208 head is smaller, its testes are more numerous and the position of its genital pore is very different from that of 0. filaroides. 0. perspicua differs from 0. lonnhergii (Fuhrmann) from Necturus maculosus Raf. in having a smaller head and smaller suckers and more numerous testes. OPHIOTAENIA LACTEA (Leidy) Sp. Inq. 1855: Taenia lactea Leidy 1855:443 1911 : Ophiotaenia lactea La Rue 1911 :481 On account of the inaccessibility of Leidy 's description, it is here quoted in full: "Taenia lactea Leidy. — Head small, continuous with the neck, without ros- tellum ; acetabula anterior, hemispherical, situated at the four angles. Neck mod- erately long. Segments anteriorly transversely oblong, posteriorly longer than the breadth, square with rounded angles. Generative apertures marginal (indistinct in the specimen.) "HAB. — One specimen i6 inches long and 5^ of a line wide was found in the intestine of Tropidonotus sipedon. In alcohol the specimen contracted one- half the original length and widened to i line." La Rue (1911:481) made this a species inquirenda in his newly established genus Ophiotaenia. This is probably a species of Ophiotae- nia and may be the same as the species reported by the writer from Natrix rhomhifer. Unfortunately the writer has had as yet no oppor- tunity to make a study of any Ophiotaenia from Natrix sipedon and hence is unable to form an opinion of the likelihood that the two species of host harbor the same parasites. Leidy 's description is too inadequate to permit a careful determination of the position of his form and since his specimens could not be had by the writer for study his species is considered to be a species inquirenda. Further research may indicate its proper position. 209] PROTEOCEPHAUDAE—LA RUE 209 OPHIOTAENIA FILAROIDES La Rue [Figs. 26-28, 43-46, 103-105] 1909: Proteocephalus filaroides La Eue 1909:17-49 1911 : Ophiotaenia filaroides La Rue 1911 :481 Specific Diagnosis: Characters of genus. Worms attenuate, small, thin, flat. Length 80-110 mm., maximum breadth about 0.80-0.90 mm. Color white, in life somewhat translucent. Strobilation not evident. Intersegmental furrows shallow. Surface smooth. Scolex globose, flattened dorsoventrally, with conical apex, without apical depression or fifth sucker. No rostellum. No spines. Head not marked by fur- rows. Breadth of head 0.366-0.46 mm. Suckers deep, muscular, oval in outline, maximum dimension 0.165-0.184 mm. Neck narrow, 3-4 mm. long. First proglottids 0.30-0.36 mm. broad by 0.10-0.17 mm. long. Mature proglottids quadrate or longer than broad. Ripe proglottids from 1.6 mm. long by 0.8 mm. broad to 4.0 mm. long by 0.75 mm. broad. End-proglottid present. Musculature weak. Parenchyma coarse, filled with large fat globules. Genital organs typical of genus. No genital papilla. Genital pore marginal, irregularly alternating, situated at end of first fifth of pro- glottid. Testes 0.05-0.06 mm. in diameter, 70-114 in number, arranged in two lateral fields. Ductus ejaculatorius with a few coils in cirrus- pouch. Cirrus weakly muscled, slender, cylindrical, 0.2-0.3 mm. long when protruded. Cirrus-pouch about 0.22 mm. long by 0.11 mm. broad. Vagina always anterior to cirrus-pouch, not crossing latter. Weak sphincter vaginae and small receptaculum seminis present. Ovarian lobes thin, alate, composed of anastomosing tubules. Organs of inter- ovarial space typical of genus. Vitellaria with large follicles. Uterus, when developed, with 25-35 lateral pouches on either side. Uterine pores 8-12. Eggs with three membranes. Outer one 0,035-0,100 mm,, second, 0.030 mm., embryo 0.021 mm. in diameter. Habitat: Intestine and rectum of Amhly stoma tigrinum (Green) [type host], Nebraska (type locality) and Kansas. Type: Unnumbered alcoholics in collection of La Rue and slides of same. Autotype in collection of Dr. H. B, Ward. This species was first described by La Rue (1909:17-49) as Proteo- cephalus filaroides. So far as the writer has been able to find out no one else has worked on the species. La Rue (1911:481) included this species in a list of species of Ophiotaenia. 210 ILLINOIS BIOLOGICAL MONOGRAPHS [210 This material was obtained from Amblystoma tigrinum (Green) caught in ponds in Nebraska, both at Crete and in Cherry County, also in a pond at Belleville, Kansas. The specimens were taken during the summers of 1907 and 1908, The data presented here are for the most part extracted from the former article (La Eue, 1909) but the data regarding the character of the fifth sucker are new. These cestodes are attenuate, thin and flat. In life they are white, at times somewhat translucent. The chain presents no evident strobi- lation, for the proglottids are closely joined by their full breadth and the intersegmental furrows are shallow. There are no longitudinal or transverse furrows in preserved specimens. The strobila measures 80- 110 mm. in length by a maximum breadth of 0.80-0.90 mm. The scolex (Fig. 26) is globose, flattened somewhat dorsoventrally, and possessing a smooth conical apex in which there is no depression nor fifth sucker. There is no rostellum and no spines. The surface of the head is usually smooth and but rarely marked by furrows. The head measures 0.366- 0.40 mm. broad. Four oval suckers are borne at the broadest part of the head. They measure 0.165-0.184 mm. in the maximum dimension. The suckers have deep cavities and their musculature is well developed. As in many other species of this group which possess no functional fifth sucker there is in the tissue below the surface of the apex of the head a structure which the writer formerly called an endorgan. This structure appears as a small mass of tissue surrounded by a definite membrane. The mass of tissue contains a few nuclei and a few scat- tered fibers which may be muscle fibers. In the adult this structure is about 0.063 mm. long by 0.034 mm. broad. It has no opening to the exterior. Two histological drawings of the adult organ are to be found in a previous paper (La Rue 1909, Figs. 13 and 17). In the plerocercus this structure is much larger than in the adult. This fact was pointed out in the author's paper of 1909 and figures were given to show the difference in size. These figures have been reproduced (Figs. 27, 28). If sections through the head of plerocereoids of this species be examined one notes that the endorgan has many points in common with the func- tional fifth sucker. There is a sucker cavity communicating with the exterior, a basement membrane, muscle fibers (sub-cuticular and radial). The musculature about the organ is also like that about other suckers. These histological features are shown in drawings which are reproduced (Figs. 43-46). This structure is, however, undergoing a marked modi- fication. The sucker cavity is completely or partially filled with a gran- ular mass of apparently the same texture as that which makes up the greater bulk of the sucker itself. The radial muscles are no longer arranged in such beautiful order as in other suckers but they seem to 211] PROTEOCEPHALIDAE—LA RUE 211 be twisted and pressed out of the regular position and spread far apart by the granular mass. Radial muscle fibers showing the most typical arrangement are to be seen in figure 45. Nuclei are plainly seen and these are figured as the larger oval black spots. The drawing of the endorgan (Fig. 43) is made from a head cut in a frontal or sagittal plane. It shows the opening to the exterior, the basement membrane and the cuticular lining of a part of this opening. It also shows the cut ends of the muscle fibers next to the basement membrane. Some of these same features may be well seen in other drawings (Figs. 45 and 46) which are drawn from transverse sections of other heads. It is evident from the structures here described and the drawings which illustrate them that this organ is in reality a sucker. It is a sucker which evidently comes to a certain state of development in which as pointed out by the writer in his former paper on this species (La Rue 1909:25), it is larger than the other suckers. The relative sizes of this organ are shown in drawings reproduced (Figs. 27, 28) from the former paper. This enlargement is due to a hypertrophy charac- terized by the presence of granules. Altho the stages succeeding this hypertrophy have not been followed out it is plain that the hypertrophy is succeeded by an atrophy of the tissues. Since the granules are not present in the adult organ they must disappear either as a result of streaming out of the sucker opening before that is closed or they may be absorbed by the organism. The sucker opening and the sucker cavity and all traces of the cutieula, outer basement membrane, and muscles about the sucker cavity are obliterated by the time this organ is found in the adult cestode head. Thus the sucker loses all connection with the exterior. It retains its limiting basement membrane, some of its nuclei and perhaps a few scattered muscle fibers. The conclusion is then that this endorgan, or muscle-plug as Johnston (1909 et seq.) has called it, is a vestigial fifth sucker. That the writer was dealing with the plerocercoids of this species is attested by the facts brought out by his feeding experiments (La Rue 1909) in which he fed plerocercoids taken from the flesh of Amblystoma to other uninfected Amblystoma and the latter became heavily infected with the cestode Ophiotaenia filaroides. The narrow neck is 3-4 mm. long. This is followed by a region of short proglottids which gradually become longer and broader. The increase in length is more rapid than the increase in breadth hence the proglottids change progressively from broader than long to quadrate and then to longer than broad. The youngest proglottids measure 0.30- 0.36 mm. broad by 0.10-0.17 mm. long. Ripe proglottids measure 1.6 mm. long by 0.8 mm. broad and in some cases as much as 4.0 mm. long 212 ILLINOIS BIOLOGICAL MONOGRAPHS [212 by 0.75 mm. broad. An end-proglottid with a rounded posterior end may be present, but it is lost with the first ripe proglottids. The musculature of the body is weakly developed. This is particu- larly true of the longitudinal muscles which lie between the cortical and medullary layers of the body. In the head the excretory system is made up of coils of small anastomosing vessels which are connected with the two pairs of main lateral vessels extending through the length of the strobila. In the strobila both pairs of lateral vessels lie within the dermo-muscular sheath. The genital canals, cirrus-pouch and vagina, always pass between the dorsal and ventral excretory vessels. The latter are connected with the exterior by numerous branches which discharge on the dorsal or ventral surface more frequently than on the margin of the segment. Regularly situated foramina secundaria do not exist. A transverse excretory commissure uniting the ventral vessels in the posterior part of the proglottid has been observed. The meshes of the parenchyma are coarse, forming numerous large spaces. In mate- rial prepared by ordinary methods this tissue appears to be nothing more than abnormally loose parenchyma. When fresh material is stained with ''Sudan III" or is treated with osmic acid these spaces are found to be filled with large fat globules. These tests have likewise been applied by the writer to pieces of 0. lonnhergii with similar results. Fat globules have been found in the tissues of species of Proteocephalus but in this case the fat globules are small. Tests have also been made on Taenia saginata (?), Taenia serrata, and Dipylidium caninum and in each case fats have been found. Tests for fat have not been made on the cestodes of snakes but all the species examined show the loose parenchyma with large spaces, which the fat globules once occupied. The genital organs (Figs. 103, 104, 105) are typical of the genus. A genital papilla is not present. The genital pore is marginal, irregu- larly alternating, and situated near the end of the anterior fifth of the proglottid. Through the genital pore the small genital atrium is con- nected with the exterior. Into the genital atrium both cirrus and vagina open. The vagina always lies anterior to the cirrus-pouch. The testes (Fig. 105) measure about 0.05-0.06 mm. in diameter. They number about 70-114 and they are situated in two broad fields on either side of a free median zone. They occupy a position dorsal to the uterus. A much coiled vas deferens forms a mass which extends from the cirrus- pouch to the midfield of the proglottid. This mass of coils functions as a vesicula seminalis. Upon entering the cirrus-pouch the vas deferens becomes the ductus ejaculatorius which makes 1-3 coils before passing over into the straight and weakly muscled cirrus. When protruded the cirrus measures 0.2-0.3 mm. in length. It is slender and of almost 213] PROTEOCEPHALIDAE—LA RUE 213 uniform diameter from base to tip. The cirrus-pouch is weakly muscled. Its length is about 0.22 mm. and its breadth about 0.11 mm., being broadest at its inner end. The vagina (Fig. 105) always lies anterior to the cirrus-pouch and does not cross the latter. There are no coils of vagina anterior to the interovarial space. A weak sphincter vaginae and a small receptacu- lum seminis are present. The lobes of the ovary are thin and somewhat alate in shape. They are made up of anastomosing tubules. The organs (Fig. 104) of the interovarial space are typical of the genus. Vitelline follicles are large and are arranged in the lateral fields as in the other members of the group. The uterus in mature proglottids is a median tube. From this tube there arise both lateral and ventral diverticula after the manner described by La Rue (1909:33-37). The lateral diverticula in fully ripe proglottids extend to the vitellaria which by this time have degenerated to a large extent. They number from 25 to 35 on either side. The ventral diverticula number about 8-12. These are short and usually pointed. In time they pierce the ventral body wall forming the uterine pores. The ventral body wall now gives way along this line of perforations thus causing a rift which extends from one end of the proglottid to the other. Through this rift the eggs are dis- charged. The eggs are covered with three membranes of the character usual to the group. The outer thin and hyaline membrane varies in diameter from 0.035 to 0.10 mm. This variation is due in part to the fact that when it comes in contact with the water the outer membrane swells up greatly. The second membrane is thick and granular, about 0.030 mm. in diameter. The inner membrane which closely invests the embryo is thin. The six-hooked embryo measures about 0.021 mm. in diameter. The larval form of this cestode is frequently found encysted in the abdominal viscera and body muscles of the host, Amhlystoma tigrinum. They have also been found free in the body cavity of the same host. As yet they have not been found in an invertebrate host. Altho this species shows marked similarities with some of the spe- cies oF cestodes infesting snakes it most nearly resembles Ophiotaenia lonnhergii (Fuhrmann) which infests the amphibian, Necturus maculo- sus Raf. It differs from this species in size relations, in the character of the excretory vessels, and in the relations of the cirrus-pouch to the vagina. There are some minor points in which the two species from the amphibia differ from the species infesting snakes but as yet charac- ters have not been found by which they can be separated from the genus Ophiotaenia. These two species certainly do not belong with the genus Proteocephalus. 214 ILLINOIS BIOLOGICAL MONOGRAPHS [214 OPHIOTAENIA LONNBERGII (Fuhrraann) [Figs. 119, 189] 1895: Ichthyotaenia lonnhergii Fuhrmann 1895:218-226 1909: Proteocephalus lonnhergii La Rue 1909:43 1911 : Ophiotaenia lonnhergii La Rue 1911 :481 Specific Diagnosis: Characters of the genus. Length as much as 17-19 cm. Breadth as much as 1.35 mm. Strobilation usually indis- tinct. Intersegmental furrows shallow. Proglottids attached by full width. Scolex globose, flattened dorsoventrally, 0.50-0.60 mm. in breadth. No rostellum, no spines, no functional fifth sucker. Suckers prominent, muscular, oval or round, deep, measuring 0.24-0.26 mm. long by 0.14-0.22 mm. broad. Opening in oval suckers 0,20 by 0.10 mm. Neck 0.375-0.54 mm. in minimum breadth, length about 2.0 mm. First proglottids about 0.5 mm. long by 0.50 mm. broad. Mature pro- glottids quadrate, 0.85-1.0 mm. square or longer than broad, measuring as much as 2.5 mm. long by 0.45-0.5 mm. broad. Ripe proglottids not observed. Two pairs of main lateral excretory vessels situated at some distance from lateral margins of strobila. Vessels spiral in form. Transverse commissure present in posterior end of each proglottid. Many branches extending from dorsal and ventral vessels to exterior. In head many branches of anastomosing vessels. Genital pore marginal, irregularly alternating, situated at end of first one-third or two-fifths of proglottid. Testes 90-160 in number, round or oval, 0.05-0.08-0.12 mm. in maximum dimension, situated in two lateral fields extending laterad of excretory vessels. Midzone of proglottid not entirely free of testes. Vas deferens forming a large mass of coils posterior to cirrus-pouch. Cirrus-pouch 0.185-0.280 mm. long by 0.05-0.085-0.10 mm. broad. Ductus ejaculatorius in several coils, frequently forming a small vesicula. Cirrus not muscular, when protruded cylindrical and 0.13-0.15 mm. long by 0.045-0.05 mm. thick. Vagina anterior or posterior to cirrus-pouch. Vaginal opening some- times dorsal to latter, but vagina never crossing cirrus-pouch. A large dilatation in vagina of some proglottids. Sphincter vaginae and recep- taculum seminis present. Ovary thin, flat, lobes wedge-shaped or alate. Organs of interovarial space typical of genus. Vitellaria sparse. Uterus in past mature proglottids possessing 25-40 lateral pouches. Eggs im- mature in specimens observed. Yolk-mass 0.010-0.012 mm. in diameter. Egg membranes not seen. Embryos not yet developed. Habitat: In intestine of Necturus maculosus Rar. Fuhrmann does not state the locality of the host from which his type specimens 215] PROTEOCEPHALIDAE—LA RUE 215 came. The writer has frequently found the species in Necturus from Ohio and Indiana which had been brought to the laboratory for dissec- tion, Fuhrmann's specimen was obtained from Prof. F. Zschokke who received it from Prof. R. Burckhardt. Type: Prepared slides in collection of Fuhrmann. Fuhrmann (1895:218-226) described and delineated this species, calling it Ichthyotaenia Idnnhergii. Without attempting a description of the species it was referred to by La Rue ( 1909 :43 ) as Proteocephalus lonnbergii. In a more recent paper La Rue (1911:481) pointed out that this was to be considered as a species of a new genus, Ophiotaenia. This study is based on slides and alcoholics in the collection of La Rue. The material has been carefully compared with Fuhrmann's preparations of the type which Professor Ward very kindly secured for the writer's use. The material was thus found to be identical with Fuhrmann's. Reference will be made from time to time to the work of Fuhrmann (1895) from which certain data were secured. This form is more robust than 0. filaroides. It may reach a length of 17.0 cm. or more. Fuhrmann's specimen, an immature worm, meas- ured 19.0 cm. The worm is thin and flat. Its breadth varies consider- ably. The maximum breadth in the writer's specimens was 1.275 mm. Fuhrmann's material had a slightly greater breadth. The strobilation is rarely distinct. The margins of the strobila are quite smooth. In- frequently the posterior part of the worm may show a distinct strobila- tion. The proglottids are attached by their full width. Transverse folds are rare but shallow longitudinal furrows are not uncommon. The scolex (Fig. 119) is somewhat globose and is flattened dorsoven- trally. On it are four prominent suckers situated on its broadest part. In breadth the scolex varies from 0.50 to 0.60 mm. There is no rostel- lum, no spines and no functional fifth sucker. The suckers are round or oval in outline with deep cavities and a strong musculature. In length the suckers vary from 0.24 to 0.25 mm. and the breadth from 0.14 to 0.22 mm. The opening of the more oval suckers measures about 0.20 by 0.10 mm. Immediately behind the head the neck has a breadth of 0.375-0.54 mm. The first traces of segmentation occur about 2 mm. posterior to the head. Young proglottids, according to Fuhrmann, measure 0.27 mm, in length. The first discernible proglottids in the writer's material are about 0.050 mm. long by 0.50 mm. broad. The length and breadth of the proglottids increase rapidly for a distance then the length increases while the breadth decreases. In this material the maximum breadth of 1.275 mm. was reached long before the proglottids were mature. Pro- 216 ILLINOIS BIOLOGICAL MONOGRAPHS [216 glottids in this region are 1,275 mm. broad by 0.30-0.40 mm. long. Mature proglottids are about 0.85-1.0 mm. square, or they may be longer than broad. Some of the elongated proglottids measure 2.5 mm. long by 0.45-0.5 mm. broad. In Fuhrmann's specimens the last proglottids were 0.7 mm. long by 1.35 mm. broad. Neither Fuhrmann nor the writer has seen the ripe proglottids. All the hosts examined by the latter had been in captivity for some time and were examined in the spring months. It may be that the parasites attain the sexually ripe condition later in the season. The excretory system (Fig. 189) is made up of two pairs of main lateral vessels, dorsal and ventral. These are situated much farther mesad than is usually the case with this group. They take a spiral path through the tissues. From them at frequent intervals smaU branches pass to the dorsal and ventral surfaces. A transverse excre- tory commissure is present in the posterior part of each segment. In the head the main excretory vessels are connected by means of many anastomosing branches. The parenchyma resembles that of 0. fla- roides. Chalkbodies of large size are abundant, especially in the head and neck. The musculature is weakly developed. The genital pore alternates irregularly, is marginal, and is situated at the end of the first third or two-fifths of the proglottid. Cirrus- pouch and vagina pass to the exterior between the ventral and the dorsal excretory vessels. The male organs mature first. Testes number from 90 to 160, the number varying greatly in the proglottids of the same strobila. Elongated testes measure 0.05-0.08 and even as much as 0.120 mm. in maximum dimension. The testes (Fig. 189) lie in two broad fields which extend laterad and mesad of the excretory vessels. In many proglottids an occasional testis lies in the midfield. The testes are dorsal to the uterus. In mature proglottids the vas deferens forms a large mass of coils which function as a vesicula seminalis. This mass of coils is usually situated posterior to the cirrus-pouch. It lies almost in the mid-field of the segment. The cirrus-pouch is short and broad. Its length varies from 0.185 to 0.290 mm. and its breadth from 0.050 in the case of the long slender pouches to 0.085-0.100 mm. in the shorter and thicker pouches. The cirrus-sheath is broadest at the inner end. The ductus ejaculatorius forms several coils and then it passes over into the slender cirrus. In some proglottids the ductus is dilated to form a small vesicle. The cirrus is not muscular. When protruded it is cylin- drical and about 0.13-0.15 mm. long by 0.045-0.050 mm. thick. There are no coils of ductus ejaculatorius in the base of the protruded cirrus. The vagina lies anterior or posterior to the cirrus-pouch but its opening is usually dorsal to the latter. When the vagina occupies the 217] PROTEOCEPHALIDAE—LA RUE 217 position anterior to the cirrus-pouch it never crosses the latter but passes beyond it and then dips down below the coils of the vas deferens. In many mature proglottids the initial part of the vagina is greatly dilated and this dilatation extends for some distance down the length of the vagina. There are no coils of the vagina anterior to the ovary but it may lie in sinuous curves. A weak sphincter vaginae close to the external opening and a small receptaculum seminis near the mid-piece of the ovary are present. The ovary varies in shape with the state of contraction of the proglottid. It is always thin and flat and is made up of anastomosing tubules as in 0. filaroides. In very broad but short proglottids the lobes of the ovary are long slender wedge-shaped struc- tures the apices of which lie in the mid-field of the proglottid. In attenuated proglottids the lobes are much shortened and broader than in long proglottids, in which case the ovary may be distinctly alate in form. The organs of the interovarial space are arranged about as delineated for 0. filaroides (Fig. 104). The vitellaria are lateral, com- posed of medium-sized sparse follicles. Since no ripe proglottids have been seen a well developed uterus cannot be described. In one proglot- tid in which a few eggs had been passed into the uterus there were from 25 to 40 lateral pouches on either side. No uterine pores have been observed. No eggs with developed embryos could be found. A few eggs which could be but poorly seen within the uterus of a toto prepara- tion showed yolk-masses measuring 0.010-0.012 mm. in diameter. The egg membranes could not be measured. Fuhrmann saw no eggs. This species tho most closely related to 0. filariodes can be readily distinguished from the latter by its larger strobila, larger head, larger suckers and larger testes. The excretory vessels are spiral structures in 0. lonnbergii but straight in 0. filaroides. The ovarian lobes are also different in size and shape. 0. lonnbergii differs from the Ophio- taenia parasitic in snakes by the position of its genital pore and by the less muscular character of its cirrus. Its ovary is also of a different shape. The position of the excretory ducts is much farther mesad in 0. lonnbergii than in any species of Ophiotaenia at present known from snakes. While further investigation may prove that the species of Proteo- eephalids infesting Amphibia are generically different from the species infesting snakes there is at present no justification in erecting a new genus for them. Their nearest allies are among the Ophiotaenia, hence the writer places them in that genus. 218 ILLINOIS BIOLOGICAL MONOGRAPHS [218 OPHIOTAENIA NATTERERI (Parona) [Figs. 139, 194, 195] 1901 1908 1911 Ichthyotaenia nattereri Parona 1901 :4-6 Ichthyotaenia nattereri Schwarz 1908:17-19 Ophiotaenia nattereri La Rue 1911 :481 Specific Diagnosis: Characters of genus. Length 75-250 mm,, maximum breadth not over 1 mm. Scblex unarmed, rounded but not spheroidal, not easily distinguished from the neck. Diameter of scolex 0.240-0.250 mm. Suckers four in number, circular, cavity deep, margin thick, diameter of suckers 0.120-0.150 mm. No rostellum and no fifth sucker. Neck long, 7-8 times the length of the head. First segments broader than long, more or less indistinct. Mature proglottids nearly quadrate. Ripe proglottids longer than broad, length of same up to 2.0 mm., breadth 0.33-0.50 mm. Last proglottids readily detached. Seg- mentation distinct. Genital aperture irregularly alternating, situated somewhat ante- rior to middle of proglottid margin. Testes 80-100, 0.042 mm. in diame- ter, situated in two lateral fields. Vas deferens a thick mass of coils extending even past the middle of the proglottid. Ductus ejaculatorius much coiled. Protruded cirrus slender, heavy at base, about 0.20 mm. long. Cirrus-pouch about 0.265-0.280 mm. long, extending from Vs-'/t across proglottid breadth. Vagina anterior or posterior to cirrus-pouch. Sphincter vaginae present. Uterus, when fully developed, possessing 15-20 lateral pouches on either side. Eggs provided with three mem- branes. Outer membrane covered with fine booklets. Eggs 0.024 mm. in diameter. Habitat: In intestine of Coluber sp. from Liguria, a district of Italy. The material was collected by Parona in December, 1897. This species was first described by Parona (1901:4-6) but the de- scription was not accompanied by drawings. Schwarz (1908:17-19) delineated and redescribed the species, using Parona 's specimens. La Rue (1911:481) included this form in a list of species of Ophiotaenia. The data upon which this description is based were secured from the descriptions of Parona (1901) and Schwarz (1908), and from observa- tions made upon slides prepared from type material which Professor H. B. Ward secured from Professor Parona. 219] PROTEOCEPHALIDAE—LA RUE 219 This cestode is thin and slender. Its observed length varies from 75-250 mm. and its maximum breadth is not over 1 mm. The segmenta- tion is distinct in the posterior region. The single proglottids are thin, and somewhat translucent. The first proglottids are broader than long and their boundaries between segments are not distinct. More mature proglottids are nearly quadrate while ripe proglottids are longer than broad. The length of ripe proglottids may be as much as 2.0 mm. and the breadth 0.33-0.50 mm. The last proglottids are easily detached from the chain. The head is small and not clearly set oif from the neck. It is unarmed, rounded somewhat but not spherical ; its diameter is 0.24-0.25 mm. It bears four circular suckers which have a deep cavity and a thick muscular wall. The diameter of the suckers varies from 0.120 to 0.150 mm. There is no rostellum and no fifth sucker. The neck is seven or eight times as long as the head. Cuticula, musculature, nervous system and excretory system are very similar in arrangement and character to the same systems in other species of the genus. The early developing sex organs may be seen in quadrate proglot- tids. The genital aperture lies somewhat anterior to the middle of the margin of the segment and it irregularly alternates from right to left. Schwarz's figure of the ripe proglottid showing the main features of the reproductive systems is reproduced (Fig. 195). The testes lie in two fields between the vitellaria, thus leaving the median zone of the proglottid free of them. They number 80-100 and measure 0.042 mm. The vas deferens forms a thick heavy coil extending from the cirrus- pouch even past the middle of the proglottid. Within the cirrus-pouch there is a very complicated mass of coils of ductus ejaculatorius. This is much more highly developed than in any other known species of Ophiotaenia. The cirrus when protruded is heavy at the base, more slender at the tip and about 0.200-0.210 mm. long. In preparations where it was incompletely protruded it measured 0.108 mm. long. The cirrus-pouch is 0.265-0.280 mm. long. In quadrate and oblong proglot- tids its length goes into the proglottid breadth from 3 to 3.5 times. The vagina opens into the common genital pore. It may lie either anterior or posterior to the cirrus-pouch. In 12 out of 18 proglottids examined by the writer the vagina had a posterior position. At the opening of the vagina a sphincter of good size is present. The course of the vagina is nearly direct to the middle of the segment, frequently crossing the inner end of the cirrus-pouch or even lying above the cirrus- pouch for its full length. From the middle of the segment its course is directly posteriad with sometimes a single loose coil just above or ante- rior to the ovaries. In the interovarial space are the usual coils of the vagina, oviduct, uterine passage, and unpaired vitelline duct; here also 220 ILLINOIS BIOLOGICAL MONOGRAPHS [220 are the oocapt, ootype, and shell-gland. The uterus appears in mature proglottids as a median tube from which later 15-20 lateral pouches arise on either side. The ovarian lobes are fairly dense compact masses. In many proglottids the ovary has a more elongated and pointed form than Schwarz delineates it. The vitellaria are lateral, follicular masses, reaching from the anterior end nearly to the posterior end of the seg- ment. According to Schwarz the eggs have three membranes. The diameter of the ^gg is 0.024 mm. The outer membrane of ripe eggs is covered with fine booklets or processes which terminate in small knobs. The writer was unable to observe these processes in his toto mounts. Schwarz 's figure of the Qgg is reproduced (Fig. 194). This species is easily differentiated from Crepidobothrium gerrardii, 0. marenzelleri, 0. calmettei, 0. racemosa, 0. trimeresuri and 0. grandis by its much smaller size, and from 0. perspicua by its slightly smaller head and suckers, by its lesser number of smaller testes, its more volumi- nous cirrus-pouch and its lesser number of uterine pouches. In many respects 0. nattereri and 0. perspicua are quite similar. 0. nattereri has a smaller head and smaller suckers than 0. pigmentata. Further comparisons with 0. pigmentata can not be made because of the incom- pleteness of the data on the latter. OPHIOTAENIA RACEMOSA (Rudolphi; [Figs. 140, 191] 1819: Taenia racemosa (?)1819: Taenia cpluhfi 1845: Taenia racemosa 1850: Taenia racemosa 1898: Ichthyotaenia racemosa 1898 : Ichthyotaenia racemosa 1908: Ichthyotaenia racemosa 1911 : Ophiotaenia racemosa Specific Diagnosis: Characters of genus. Length of strobila as much as 160 mm., breadth about 1 mm. Length of ripe proglottids about 2 mm., breadth 1 mm. Scolex easily distinguishable from strobila, breadth about 0.54 mm. Suckers four, nearly circular, 0.27-0.30 mm. in diameter. Genital organs as in genus. Testes about 100-120 in number, 0.072-0.078 mm. in diameter, located in two broad fields which tend to fuse at middle. Ductus ejaculatorius sinuous. Cirrus-pouch long, reaching nearly to middle of proglottid. Vagina anterior or pos- Rudolphi 1819 :692 Rudolphi 1819 :709 Dujardin 1845 :610 Diesing 1850:511, in part Barrois 1898:3 Liihe 1898 :652 Schwarz 1908 :28-29 La Rue 1911 :481 221] PROTEOCEPHALIDAE—LA RUE 221 terior to cirrus-pouch. Ovary voluminous, lobes somewhat winglike. Uterus possessing about twenty long outpocketings on either side. Eggs provided with three membranes. Diameter of egg 0.024 mm. Habitat: In intestine of South American snakes of the family Colubridae, subfamily Colubrinae. Host Locality Collector Authority Coluber sp. Ophiomorphus miliaris Ophiomorphus miliaris Ophis merremii Ophis merremii Brazil Brazil* Brazil* Brazil* Brazil* Natterer Natterer Natterer Natterer Natterer Rudolphi, 1819:692 Diesing, 1850:511 Schwarz, 1908:28 Diesing, 1850:511 Schwarz, 1908:28 This species was first described by Rudolphi (1819 :692). Since this description is not readily accessible to many workers it is quoted in full : "Taenia racemosa R. n, sp. Pone Synops. n. 52. "T. Capite obconico, collo brevi, angustissimo, articulis planis, elongatis, fora- minibus marginalibus alternis prominulis. Hab. In intestinis Colubri n. 20. speci- men sexpollicare et fragmenta hujus Taenia Natterer in Brasilia reperit, "Caput antrorsum dilatatum, sive obconicum, osculis orbicularibus, aut hemis- phaericis, nam satis profunda videntur, anticis, Collum breve, angustissimum. Articuli, quos vidi, plani, tenues, elongati, lineam ad sesquilineam longi, tertia lineae parte latiores, foraminibus marginalibus alternis, prominentibus. "Ovaria singulorum articulorum lineam mediam fere totam sibi vindicant, ad cujus latera utrinque maculae exiguae opacae ita digestae sunt, ut ovaria racemosa appareant. "Obs. Caput Taeniae omphalodis Synops. n. 9. articuli vero T. tuberculatae n. 25. ut fragmenta, quae vidi, Taeniam illis intermediam reddant." Rudolphi (1819:709) established the name Taenia colubri to desig- nate a few proglottids found in Coluber sp., Brazil by Natterer. His exact words are here quoted : "Taenia Colubri. Pone Synops. n. 140. Fragmenta in intestinis Colubri n. 12. a Natterero in Brasilia reperta Museo Viennensi debeo lineam circiter longa, duodecim ad octodecim articulis constantia, latioribus quam longis, subcuneatis, angulis plus minus exstantibus, capite destituta. "Utrum vere colubrina, an ex ave quadam deglutita forsan residua?" Dujardin (1845:610) added nothing to Rudolphi 's description. Diesing (1850:511) gave a short diagnosis of a form from the museum at Vienna which he identified as Taenia racemosa Rud. His description ♦Material found in Vienna Museum. £22 ILLINOIS BIOLOGICAL MONOGRAPHS [222 varies so widely from that of Rudolphi and his list of hosts covers such a range of families that his words are quoted in full: "Taenia racemosa Rudolphi. Caput magnum tetragonum, acetabulis angu- laribus subterminalibus v. terminalibus, subovatis v. cordatis. Collutn nullum. ArticuH supremi brevissimi, subsequentes longiores et latiores, angulis rotundatis, ultimi longi parallelopipedi angustiores. Penes filiformes basi incrassati, margi- nales vage alterni. Longit. 2" — ij^'; latit. med. i — 3"'; ultim. 1"'. "Taenia racemosa Rudolphi: Synops. App. 692 — Dujardin: Hist. nat. des Helminth. 610. "Habitaculum. Ophiomorphus miliaris, Martio. — Eunectes Scytale, Octobri, Februario et Junio. — Bothrops Mararacca, Martio et Aprili. — Ophis Merremii, Januario, in Brasilia {N alter er) : in intestinis. M. C. V." Von Linstow (1878:183) did no more than refer to Rudolphi (1819) and Diesing (1850). Barrois (1898:3) was convinced that Taenia race- mosa Rud. belonged to the genus Ichthyotaenia for he had examined a head and some ripe proglottids ''provenant du type primitif de Rudol- phi." He did not describe the species. Liihe (1898:652) stated that Taenia racemosa belonged to the genus Ichthyotaenia. Marotel (1899: 34) quoted Diesing 's (1850) description of this species which he stated was too incomplete to permit a precise determination. Parona (1901: 3) reported some specimens collected by Dr. Adolf Lutz from Bothrops (Lachnis) lanceolata, Sao Paulo, Brazil under the name of Ichthyotac' nia racemosa Rud. These specimens which have been examined by the writer prove to belong to the species Ophiotaenia calmettei Barrois. Shipley (1905:101) reported some cestodes from Eunectes murinus Wagler as Taenia racemosa- Rud. Professor H. B. "Ward secured some specimens labelled with this name from Mr. Shipley. Upon examina- tion they proved to be specimens of Crepidobothrium gerrardii (Baird). Schwarz (1908:28-29) secured some material from Barrois which the latter had obtained from Dr. E. von Marenzeller of Vienna. He also secured additional material from Dr. E. von Marenzeller. Upon this material he based his description of Taenia racemosa Rud. He did not definitely state the name of the host from which his material was col- lected but evidently quoted Diesing 's (1850) list of hosts. La Rue (1911:481) included this form in a list of species of the genus Ophio- taenia. It is possible that T. coluhri Rud. collected by Natterer in Brazil from Coluber sp. is a sjTionym of T. racemosa Rud. also collected by Natterer in Brazil from a species of Coluber. Rudolphi 's description of T. coluhri is insufficient to place the species, nor is there any data as to exact host and locality that would fix it. Diesing (1850:558) states 223] PROTEOCEPHALIDAE—LA RUE 22Z that T. colubri was collected by Natterer in Brazil from Ophiomorphus poecilogyrus. He gave no descriptive data and nothing that would be of assistance in placing Rudolphi's species. Diesing's (1850) diagnosis of Taenia racemosa Rud, does not agree with Rudolphi's description of that species. His statements in regard to the tetragonal head, the ter- minal or subterminal angular suckers which are subovate or cordate fits the diagnosis of Crepidobothrium gerrardii but not that of Ophio- taenia racemosa. The latter species has orbicular suckers. Likewise Diesing's statements that there is no neck, that the first proglottids are very short, following ones larger and broader, with rounded angles, the last proglottids long parallelopipeds and somewhat narrow agree much better with the descriptions of C. gerrardii than with that of 0. race- mosa. Diesing's form was considerably larger than Rudolphi's. No completely protruded cirrus was noted in the writer's material of C. gerrardii hence the cirri of the two forms cannot be compared. More- over, Diesing lists Eunectes scytale as a host of Taenia racemosa. Eunec- tes scytale is a synonym of Eunectes murinus, a species in which C. gerrardii, but no other Proteocephalid, has been found. It seems prob- able therefore that Diesing's diagnosis of Taenia racemosa was based on the material from Eunectes murinus (scytale). A further analysis of Diesing's list of hosts of Taenia racemosa shows that besides the Boidae, represented by Eunectes murinus, the Colubridae are represented by two species and the Viperidae by one species. From this evidence it seems probable that Diesing's Taenia racemosa must have included several species, for among the species of Ophiotaenia from snakes which have been adequately described in recent years no species has been found in hosts belonging to different families. A list of these species, their hosts, and their distribution is found else- where. Another fact to be remarked about these Proteocephalid species from snakes is that the individuals which infest the Boidae are larger than the individuals of the species which infest the Viperidae and these in turn are larger than those that infest the Colubridae. By the term size the writer means size of head, size of suckers, breadth of neck, breadth and length of proglottids and length of strobila. In certain of these characters the writer's general statement fails but, considered in a broad way, it is true. This is an additional reason for supposing that Diesing included several species under the one name Taenia racemosa. Concerning hosts of Taenia racemosa Schwarz (1908:28) says: "Als Wirte werden angegeben: Ophiomorphus miliaris, Ophis Merre- mii, Bothrops jararacca (for mararacca) und Eunectes scytale, Schlan- gen, die in Brazilien vorkommen". This seems to be but a restatement 224 ILLINOIS BIOLOGICAL MONOGRAPHS [224 of Diesing's list of hosts. Nowhere does Sehwarz state definitely the exact host from which his specimens were taken. A study of his de- scription in comparison with other species from snakes shows that his specimens are most closely related to the species from Colubrinae yet they are distinct from any of those species. It seems then quite prob- able that his specimens came from one of the Colubrinae, Coluber sp. and possibly Ophiomorphus miliaris or Ophis merremii. They surely did not come from Eunectes, and it is highly improbable that they came from Bothrops, one of the Viperidae. The emended list of hosts of Taenia racemosa then contains these names, Coluber sp., Ophiomorphus miliaris and Ophis merremii. Further questions regarding Sehwarz 's Taenia racemosa arise. Is his species identical with Eudolphi's Taenia racemosa f Could Sehwarz have had any of Rudolphi's type material? At the writer's request Professor Ward wrote to Professor E. von Mar- enzeller at Vienna for information concerning the specimens of Taenia racemosa which he had sent to Barrois and to Sehwarz. Professor von Marenzeller replied that all of Rudolphi's types were in the Museum at Berlin. It is therefore impossible that Sehwarz or "Barrois had Rudol- phi's type specimens for examination and the question of the identity of Sehwarz 's Taenia racemosa and Rudolphi's species of that name re- mains open and must so remain until Rudolphi's types are re-examined, if they still exist. Meanwhile the writer assumes that the Taenia race- mosa of Sehwarz and Rudolphi are identical. Sehwarz 's material all came originally from the Museum at Vienna, some directly through von Marenzeller, and some through von Maren- zeller to Barrois, then from Barrois to Sehwarz. As hosts he mentioned four species of South American snakes two of which have been ruled out in the above discussion, leaving either or both Ophis merremii and Ophiomorphus miliaris as probable hosts. If the specimens were from Ophis merremii they were probably collected by Natterer in Brazil. The following description is based on the work of Sehwarz (1908). The observed length of specimens was 160 mm., length of ripe proglottids 2 mm. and the breadth of the same 1 mm. The scolex (Fig. 140) is readily distinguished from the strobila. It bears four nearly circular suckers which measure 0.270-0.300 mm. in diameter. The scolex has a diameter of 0.540 mm. The sexual organs (Fig. 191) agree in arrangement with the genital organs of other Ophiotaenia. The testes are of exceptional size, 0.072- 0.078 mm. in diameter, appearing as large spheres. They are not limited to the side fields but are scattered irregularly through the whole area of the segment. The testicular field is not interrupted at the anterior or posterior margin of the segment. Testes number about 100-120. The 225] PROTEOCEPHALIDAE—LA RUE 225 ductus ejaculatorius takes a sinuous course through the cirrus-pouch but it forms no coils. The cirrus-pouch lies perpendicular to the longi- tudinal axis of the proglottid and reaches almost to the median line of the same. Female organs are as in other members of the genus. The vagina opens either anterior or posterior to the cirrus-sheath. The ov.ary is voluminous, bilobed, joined at the middle by a mid-piece. The ovarian lobes are somewhat plumper in form than are those of 0. marenzelleri. The uterus forms about 20 long diverticula on either side. In Schwarz's drawing (reproduced Fig. 191) the genital pore is marginal and at the end of the first third of the proglottid. The eggs are round and have three membranes. No booklets are to be found on the outer membrane. Schwarz does not state whether the diameter of 0.024 mm. is the diame- ter of the entire egg or of the embryo. Ophiotaenia racemosa is a much smaller species than Crepidohoth- rium gerrardii. Its head and suckers are smaller, the proglottids shorter and narrower. The form of the suckers is greatly different in the two species. 0. racemosa differs from 0. calmettei in its smaller head, smaller suckers, in the distribution of testes and in the number of uterine pouches. 0. racemosa is likewise much smaller than 0. marenzelleri and O. grandis in length, breadth, size of head, and size of suckers. It also has fewer testes. 0. racemosa differs from 0. timer esuri in being somewhat smaller. Its chief differences lie in the position of the testes and in the character of the cirrus and vagina. 0. racemosa differs from 0. pigmentata in having larger suckers. 0. pigmentata is too poorly described to furnish more diagnostic differences. 0. racemosa differs from 0. nattereri and 0. perspicua in having a larger head, larger suck- ers, a different arrangement of testes, and smaller proglottids. 226 ILLINOIS BIOLOGICAL MONOGRAPHS [226 OPHIOTAENIA PIGMENTATA (von Linstow) [Fig. 160] 1908: Ichthyotdenia pigmentata von Linstow 1908:85 1911: Ophiotaenia pigmentata La Rue 1911:481 Von Linstow (1908) described this species from a specimen which Edward Jacobson had collected in Java (Semarang). La Rue (1911: 481) put this form in the genus Ophiotaenia. Unfortunately the speci- men was immature so von Linstow 's description is necessarily incom- plete. His description reads: "Ichthyotaenia pigmentata, n. sp. — Aus der Schlange Psammodynastes pulver- ulentus Fisch. — Darm. Lange 32mm., Breite vom 0.51mm., hinten 1.78mm.; ein •sehr lange Strecke ist ungegliedert, nur der letzte 2.smm. lange Theil zeigt deutliche Proglottiden- bildung; es ist nur ein noch voUig entwickeltes Exemplar vorhanden. Der Scolex ist abgerundet und nicht breiter als die folgende Strecke; die Lange des Scolex betragt 0.57 mm. ; die kreisrunden Saugnapfe messen o.i8mm. ; ein Rostellum und Haken fehlen. Die Glieder am Hinterende sind 0.13mm. lang; ihre Breite betragt 1. 1 mm., die Dicke 0.25mm. Die Cuticula ist 0.0052mm. dick und tragt an ihrer Aussenseite einen 0.0065mm. dicken Stabchenbesatz. Die Muskulatur ist stark entwickelt und man unterscheidet 6 verschiedene Muskelarten, i, Ring-und 2, Langs- muskeln in diinnerer Lage unter der Cuticula ; an Parenchymmuskeln 3, aussere, 4. innere" Langsmuskeln, letztere bestehen aus Muskelbiindeln, 5. Dorsoventral ; und 6. Transversalmuskeln. In jedem Querschnitt erkannt man etwa 20 Langsgef asse ; die Hauptlangensnerv-enstamme verlaufen 1/5 des Querdurchmessers der Proglot- tide vom Rande entfemt; massenhaft finden sich dunkel pigmentirte, meistens eiformige, durchschnittlich 0.026mm. lange und 0.021mm. breite Kalkkorperchen. Nur in den letzten Proglottiden findet man eine Anlage der Geschlechtsorgane, besonders deutlich ist jederseits nach innen vom Nerv der rundliche Dotter stock; trotz der geringen Entwicklung der Geschlechtsorgane ist es zweifellos dass die Art zu Ichthyotaenia gehort". This is probably a species of Ophiotaenia. The presence of lateral vitellaria removes it from the genus Oochoristica. It must, however, be placed in the list of incompletely described species. . ^ 227] PROTEOCEPHALIDAE—LA RUE 227 1898 1898 1908 1911 OPHIOTAENIA TRIMERESURI (Parona) [Figs. 106-108, 141, 142, 192, 193] Taenia trimeresuri Parona 1898:7-11 Ichthyotaenia trimeresuri Liihie 1898:652 Ichthyotaenia trimeresuri Schwarz 1908:33-35 Ophiotaenia trimeresuri La Rue 1911:481 Specific Diagnosis: Cliaracters of genus. Length up to 105 mm. Iklaximum breadth 0.75-1.5 mm. Scolex unarmed, without rostellum, broader than necli, breadth 0.75 mm. Suckers prominent, hemispherical, muscular, 0.16-0.25 mm. in diameter, situated anteriorly. No fifth suclier. Necli short, three times length of head, breadth 0.25-0.5 mm. First proglottids broader than long. IVIature proglottids quadrate or longer than broad. Angles of proglottids not prominent. Strobilation indistinct. Genital pore situated near middle of proglottid margin, irregularly alternating in position. No genital papilla. Genital sinus if present very shallow. Testes 100-108 in number, measuring 0.063 by 0.027 to 0.080 by 0.027 mm., situated in two fields not near vitellaria. All testes anterior to ovary. Mass of coils of vas deferens not large. Ductus ejaculatorius much coiled. Cirrus muscular. Many coils of ductus ejaculatorius in base of protruded cirrus. Cirrus-pouch about 0.270- 0.330 mm. long by 0.136 mm. broad. Ratio of length of cirrus-pouch to proglottid breadth 1 :4 or 2 :5. Vagina anterior or posterior to cirrus- pouch, not crossing same. Lumen of vagina variable in size. Sphincter vaginae present. Lobes of ovary flattened, elongated, narrow. Vitel- line follicles small. Uterus when fully developed with 20-30 (?) lateral pouches. No ripe eggs observed. Habitat : In the intestine of Trimeresurus formosus (type host) ; Island of Mentawei, East Indies (type locality). Type: Specimens in Professor C. Parona 's collection labelled " Arynchotaenia trimeresuri Par., Trimeresurus formosus, (Mentawei)." Also twb toto preparations of the same material in the collection of Professor H. B, Ward. Parona ( 1898 :7-ll ) first described and figured this species without discovering its relation to the Proteocephalidae. Liihe (1898:652) 228 ILLINOIS BIOLOGICAL MONOGRAPHS [228 stated that this species belonged to the Ichthyotaenia. In a footnote he says, "Herr Prof. Parona hat mir die Original-exemplare der Art in uneigenniitzigster Weise zur VerfUgung gestellt, so dass ieh die Zuge- horigkeit derselben zu der Gattung Ichthyotaenia feststellen konnte." Sehwarz (1908:33-35) had no specimens of this species for examination. He rewrote Parona 's description but was able to add nothing new. He believed this form to be a species of Proteocephalus and called attention to the fact that the lower part of the uterus in Parona 's drawing was probably the ovary and that the testes would be found in the anterior region of the proglottid where they were frequently difficult to see. La Rue (1911:474) stated that this species belonged with the genus Ophiotaenia and gave a few of its characters. Thanks to Professor H. B. Ward who secured this material from Professor Parona for the purpose of this study the writer has been able to give this species a more careful description than has hitherto been attempted. The material consists of about a half dozen pieces among which no head could be found. This material is labelled " Arynchotae- nia trimeresuri Par., Trimeresurus formosus (Mentawei) ". From it two toto preparations were made. These together with the alcoholics and Parona 's original description form the basis of the following description. In the material at the writer's disposal the head, neck and first proglottids were missing. The pieces measured 10, 20, 60 and 70 mm. long by a maximum breadth of about 1.0 mm. Parona in a table gave data concerning the length and breadth of five specimens with heads and five without. The length of those with heads ranged from 12 to 50 mm. and the maximum breadth from 0.75 to 0.1 mm. while the headless specimens measured 33-105 mm. in length by a maximum breadth of 0.75-1.5 mm. The scolex is spheroidal, has neither hooks nor rostellum, and is broader than the neck. Its diameter is about 0.75 mm. The suckers are prominent and are situated in the anterior part of the head. They are hemispherical, strongly muscular, and have a diameter of 0.16- 0.25 mm. The aperture of the sucker is 0.11-0.16 mm. Parona 's draw- ings of the scolex are reproduced (Figs. 141, 142). The neck is about three times as long as the scolex. Its breadth varies from 0.25 to 0.5 mm. The first proglottids tho broader than long are not very short. These become successively longer, the last being long- est. The increase in length, however, is not constant because short pro- glottids are to be found between long ones. Nor is the breadth of the strobila constant. Some proglottids are about quadrate while others are 2-3-4 times longer than broad. Proglottid limits are poorly defined ren- dering the strobilation indistinct. The angles of the proglottids are not 229] PROTEOCEPHALIDAE—LA RUE 229 prominent hence the worm has the appearance of a continuous ribbon. The description thus far is based on the original description as given by Parona (1898:8-9). In the toto preparations which the writer has studied there were a few mature proglottids one of which is delineated (Fig. 108). The uterus of this proglottid contained a few eggs but these have been omitted in the drawing. This segment measured 1.7 mm. long by 0.9 mm. broad. It was thin and flat but considerably thicker than proglottids of an equal state of development from 0. per- spicua or 0. natterer. A genital pore is situated near the middle of the margin of each proglottid. It alternates irregularly from left to right. There is no genital papilla nor is the pore marked by a deep depression as is some- times the case in 0. grandis. The vagina and cirrus-pouch open very near each other but in this toto preparation it was impossible to tell whether there was a common genital sinus. If present at all it was very shallow. The other drawings (Figs. 106, 107) do not show such a structure. Testes (Fig. 108) are 100-108 in number. Their dimensions are 0.063 by 0.027 mm. to 0.080 by 0.027 mm., the long axis being perpen- dicular to the long axis of the worm. They are arranged in narrow bands situated well away from the vitellaria. In this respect the species resembles 0. calmettei. None of the testes are posterior to the ovaries though Parona 's drawing which has been reproduced (Fig. 193) for purposes of comparison shows them there. The vas deferens (Fig. 108) forms a small mass of coils in the mid-region of the proglottid. Within the cirrus-pouch is the much coiled ductus ejaculatorius (Fig. 107). The ductus passes over into the thicker- walled and more muscular cirrus. When under certain conditions the cirrus is protruded the greater part of the ductus ejaculatorius is crowded out into the dilated basal part of the cirrus (Figs. 106, 107). In this condition the cirrus is very similar to that described and figured by Schwarz (1908) for 0. maren- zelleri. He, however, claimed that the whole cirrus-pouch was evagi- nated. In this he misinterpreted the facts for only the cirrus and a part of the ductus are pushed out. Schwarz 's drawing (reproduced Fig. 199) shows the cirrus-pouch in its normal position. In 0. marenzelleri the distal half of the evaginated cirrus is filiform. This condition has not been seen in the present species yet it seems highly probable that a part of the coils of the ductus can be pushed through the basal part of the cirrus and thus form a filiform cirrus. Unless this be the case it is difficult to understand how copulation can be possible. The large number of coils of ductus ejaculatorius in this species furnishes a dif- ferentiating character between this species and 0. marenzelleri. The 230 ILLINOIS BIOLOGICAL MONOGRAPHS [230 cirms-poueh (Fig. 107) is large and very muscular. Its length varies from 0.27 to 0.34 mm. Its breadth is about 0.136 mm. and its length, according to Parona, is 0.33 mm. The ratio of the length of the cirrus- pouch to the breadth of proglottid is 1 :4 or 2 :5. The vagina lies either anterior or posterior to the cirrus-pouch, but it does not cross the latter. Its course after reaching the median field is frequently quite sinuous. Near its opening (Figs. 106, 107) it has a very heavy sphincter muscle. In some parts of the vagina its lumen is narrow while in other regions it may be widely dilated. The lobes of the ovary are flattened. They are more elongate and narrower than in 0. marenzelleri. The paired vitelline ducts cross the ovary on the ventral side. The uterus in mature proglottids is a median tube ex- tending the length of the proglottid. No ripe proglottids could be examined so the number of lateral uterine out-pocketings could not be accurately determined. The drawing, however, (Fig. 108) indicates that probably about 20-30 lateral pouches would be developed on either side. No ripe eggs were present in the material examined. The description and drawing of the mature proglottid shows this to be a species which falls readily into the group of Proteocephalids infesting snakes. The writer's description and drawings do not agree very well with Parona 's except as to size, position of genital pore and length and shape of cirrus-pouch. From his drawings which have been reproduced (Figs. 192, 193) it appears that he has confused certain organs. The lower portion of the uterus in his drawing is undoubtedly the bilobed ovary. The position of the testes posterior to the ovary in his figure cannot be explained except on the supposition that he mistook parts of the organs af the interovarial space for testes. The sinuous duct which he shows as the vas deferens extending back from the cirrus- pouch to the ovary is not the vas deferens but the vagina which in fact passes below the coils of vas deferens before reaching the middle of the proglottid. The mass of coils of the vas deferens is poorly shown at the inner end of the cirrus-pouch. The opening of the vagina, the vaginal sphincter and the first part of vagina along the length of the cirrus-pouch he has omitted altogether or he has confused these with a part of the cirrus-pouch. The cirrus-pouch as he drew it seems to be made up of lamellae. In a poor preparation the cirrus-pouch might have had this appearance. The cirrus within the cirrus-pouch is not properly delineated. The uterus in an early stage may possibly have had the single anterior lateral pouch on either side as he has shown it. The writer has not seen a proglottid as nearly ripe as this one was and so is not able to judge as to the actual structure of the uterus. The testes and vitellaria he (Parona) has omitted from his drawings. It 231] PROTEOCEPHALIDAE—LA RUE 231 seems highly probable that Parona's drawings are intended to represent the same species as do the writer's. The apparent difference probably came about through Parona's using poor preparations for study. 0. trimeresuri (Parona) in size is much smaller than 0. grandis, 0. marenzelleri and Crepidohothrium gerrardii. Moreover in number and arrangement of testes, size and proportions of cirrus-pouch and cirrus these three species differ greatly from 0. trimeresuri. In size this species is more nearly related to 0. calmettei but in the latter species the relations of the cirrus, cirrus-pouch and vagina are different. The testes in 0. trimeresuri are arranged much as they are in 0. cal- mettei but the size of the head and the suckers differ greatly. 0. nat- tereri and 0. perspicua are smaller, more delicate and have very differ- ent relations of cirrus, cirrus-pouch, vagina, and testes. This form differs from any other species thus far described from snakes yet it has its closest affinities with 0. calmettei, likewise parasitic in one of the Crotalinae. 1898 1898 1898 1899 1901 1908 1911 OPHIOTAENIA CALMETTEI (Barrois) [Figs. 11, 109, 110, 155, 156, 197, 198] Ichthyotaenia calmettei Ichthyotaenia raillieti Ichthyotaenia calmettei Ichthyotaenia calmettei Ichthyotaenia racemosa Ichthyotaenia calmettei Ophiotaenia calmettei Barrois 1898:1-3 Marotel 1898 :99-101 Liihe 1898 :652 Marotel 1899 :34-42 Parona 1901 :3 Schwarz 1908 :24-26 La Rue 1911 :481 Specific Diagnosis: Characters of genus. Observed length 27-40, and even up to 80 cm. Maximum breadth 0.97-1.2-2.0 mm. Proglottids numerous, first broader than long, subsequent ones quadrate or even much longer than broad. Mature proglottids about 0.85 ram. square. Ripe proglottids 2-3-4 mm. long by 1.0-1.2 mm. broad. Strobilation not clear. Scolex spheroidal or tetragonal, without rostellum, without hooks, without fifth sucker. Anterior face of same flattened, with small eleva- tion at center. Head 1.0-1.3 mm. broad, 0.60 mm. long, 0.935 mm. thick. Suckers four, somewhat globular, with deep cavity. Diameter of sucker opening 0.12-0.17-0.185 mm. Diameter of sucker 0.27-0.300-0.408 mm. Neck 0.580-0.980 mm. broad by 4-5-8 mm. long. Genital organs typical of genus. Genital aperture irregularly alter- nating. Situated at or near middle of proglottid margin. Genital sinus ut ILLINOIS BIOLOGICAL MONOGRAPHS [232 shallow. Vagina anterior or posterior to cirrus-pouch. Vaginal opening frequently dorsal to cirrus-pouch. Testes 130-160 in number, arranged in two lateral fields. Size of testes 0.026-0.04-0.06 by 0.053-0.07 mm. Vas deferens a mass of coils extending from cirrus-pouch to mid-field. Cirrus-pouch 0.25-0.29-0.33 mm. long by 0.100-0.136 mm. broad. Ratio of length of cirrus to proglottid breadth 1 :6-l :5 in mature and 1 :4 in ripe proglottids. Ductus ejaculatorius with numerous coils. Cirrus broad, muscular, not seen protruded. Vagina broad at distal end, never crossing cirrus-pouch in course to mid-field. Course of vagina to interovarial space sinuous. Sphincter yaginae present. Receptaculum seminis not seen. Ovarian lobes slender in young proglottids, broad in old. Vitellaria with small follicles. Uterus when fully developed possessing 24-35 lateral pouches on either side. Uterine pores ventral, 2-4-5 in number. Eggs provided with three membranes. Outer membrane variable in size, second one thicker, 0.022-0.024 mm. in diameter, inner one granular, irregular, 0.014 mm., embryo 0.012 mm. Habitat: In intestine of Lachesis (Bothrops) lanceolatus L. Host Lachesis (Bothrops) lanceolatus L. Lachesis {Bothrops) lanceolatus L. Lachesis (Bothrops) lanceolatus L. Locality Collector Authority Martinique Calmette Barrois Martinique Guerin Marotel Sao Paulo, Adolf Lutz La Rue (the Brazil present paper) Barrois' (1898) description of this species while meager and un- accompanied by drawings agrees fairly well with the descriptions of later investigators. His specimens came from Lachesis (Bothrops) lan- ceolatus L. from Martinique from which host they were secured by Professor Calmette. Later in the same year Marotel (1898) briefly described this species under the name /. raillieti. His specimens came from Lachesis (Bothrops) lanceolatus L. from Martinique. Liihe (1898) called attention to the fact that I. raillieti was a synonym of /. calmet- tei, and he included the form in his list of species of Ichthyotaenia. Marotel (1899:34-42) in a more extended paper described this species. His paper is accompanied by several drawings. Parona (1901) listed this species in a record of parasites from South America under the name of Ichthyotaenia racemosa. His speci- mens are from B. lanceolatus L. from Sao Paulo, Brazil. Schwarz (1908:24-26) added but little to the work of Barrois and Marotel. He 233] PROTEOCEPHALIDAE—LA RUE 233 determined that there was no rostellum. La Rue (1911:481) included this form in a list of species of Ophiotaenia. This study is based on material which Professor H. B. Ward secured for the writer's study from Professor Parona. Professor Parona's material bore the label, "T. (Oochoristica) racemosa S. Paulo, race. A. Lutz." This is evidently the material on which Parona (1901) based his report. There he stated that it came from Bothrops lanceo- latus L. The material consisted of seven or eight pieces to one of which a head was attached. The head was cleared in glycerine and studied in that condition while some of the smaller pieces were stained and mounted as toto preparations. The identification of the material was made from these preparations. The report is also based upon data secured from the papers of Barrois (1898), Marotel (1899), and Schwarz (1908). The longest piece which the writer observed measured 270 mm. long by 2.0 mm. broad. Barrois (1898) states that he observed a length of 35-80 cm. by a breadth of 0.97 mm. for this species. Marotel's (1899) specimens measured up to 35-40 cm. long by a maximum breadth of 1.2 mm. Schwarz (1908) reported a breadth of 1.5 mm. The strobila is made up of many proglottids, according to Barrois as many as 289. The proglottids are closely joined to one another. As a rule no inter- segmental furrows can be seen with the unaided eye. In a single piece the strobila was strongly contracted and here the strobilation was evi- dent. The surface of many of the proglottids is thrown into numerous longitudinal folds. The scolex is club-shaped according to Barrois and Marotel, sphe- roidal according to Schwarz. The figures of the head as delineated by Marotel and Schwarz are reproduced (Figs. 155, 156). Barrois and Schwarz reported that there was no fifth sucker and no rostellum while Marotel thought that the slight elevation at the middle of the head (Fig. 156) was a rudimentary rostellum. He saw no fifth sucker. Marotel states that the globular suckers are directed anteriad. The head (Fig. 11) which the writer observed was cleared in glycerine. It presents a somewhat tetragonal face with a small elevation at its center which is not a rostellum and upon which there is no fifth sucker. The suckers are placed in the corners of the anterior face and they are directed anteriad. Slight grooves or wrinkles which do not extend to the apex partially divide the head into quadrants. The suckers are nearly round in outline and they lack any trace of the inturned lower margin which is a characteristic of the suckers of Crepidohothrium gerrardii. Suckers measure 0.39-0.408 mm. in diameter while the open- ings of the suckers measure 0.17-0.185 mm. in diameter. The sucker 234 ILLINOIS BIOLOGICAL MONOGRAPHS [234 2avity is deep. This head is 1.19 mm. broad, 0.60 mm. long, 0.935 mm. thick. The comparative table which follows presents the data on the head as secured by Barrois, Marotel, Schwarz, and the writer. Head Suckers Diameter of sucker opening Authority Shape Size Shape Diameter Club-shaped breadth 1-1.3 mm. breadth 1.05 mm. breadth i.omm. breadth 1.19 mm. length 0.60 mm. thickness 0.935 r"in- lo/iZ-ci.TA mm Barrois (1898:2) Club-shaped Spheroidal Somewhat tet- ragonal globular 0.27-0.30 mm. 0.30-0.34 mm. 0.39-0.408 mm. 0.120 mm. 0.120 mm. 0.1 7-0. 185 mm. Marotel (1899:36) Schwarz (1908:24) round in outline La Rue (the present paper) The neck of the specimen observed by the writer measured about 5-8 mm. long by 0.980 mm. broad. Its limits could not readily be de- termined in a glycerine preparation. Marotel states that the neck is 4 or 5 mm. long and 0.580 mm. broad at its narrowest place. Barrois and Schwarz do not state its dimensions. The first proglottids are much broader than -long. These increase in length more rapidly than in breadth. Marotel (1899) states that at 20 mm. from the head the pro- glottids measure 0.255 mm. long by 0.63 mm. broad ; at 25 mm. 0,65 by 0.65 mm. i. e., they are quadrate ; at 30 mm., 0.71 mm. long, 0.67 mm. broad ; at 40 mm., 1.45 by 0.75 mm., and the last proglottids are 3 to 4 mm. long by 1.0 mm. broad. In material examined by the writer nearly mature proglottids measure as much as 0.9 mm. broad by 0.55 mm. long and mature proglottids about 0.85 mm. square or some of them may be a little longer than broad. Ripe proglottids measure 2-3 mm. long by 1.0-1.2 mm. in breadth. In some contracted regions of the strobila the breadth may measure as much as 2.0 mm. The sexual aperture is irregularly alternating, situated in mature proglottids at or slightly anterior to the middle of the margin. In ripe proglottids it may be either anterior or posterior to the middle. Both cirrus and vagina open into a common genital sinus which is very shallow. The vagina lies anterior or posterior to the cirrus-pouch with almost equal frequency. In ripe proglottids frequently and in mature proglottids more rarely, the vagina may open dorsal to the cirrus- pouch. The testes (Figs. 109, 110) number from 130 to 160 in the writer's preparation and these numbers are also about the limits observed by the other investigators. They measure from 0.026 to 0.037 mm. by 0.053 to 0.063 mm. in the writer's preparations. Others report them as measur- 235] PROTEOCEPHALIDAE—LA RUE 235 ing 0.06 by 0.04 mm., 0.062-0.072 mm., and 0.07 by 0.04 mm. They are arranged in two fields which in elongated proglottids are near the ventral excretory vessels while in contracted proglottids (Figs. 109, 110) they are some distance from the ventral vessels. In the former ease the testes of each field are arranged in two irregular rows while in the latter case the testes of each field are irregularly arranged in a broad zone. The testes are dorsal to the uterus. The vas deferens forms a mass of coils which extend from the cirrus-sheath nearly to the middle of the proglottid. The writer's drawings (Figs. 109, 110) show it more heavily developed than do the figures of Marotel (1899) which are reproduced (Figs. 197, 198). The cirrus-pouch is relatively short and broad, 0.25-0.29 mm. long by 0.100-0.136 mm. broad. In the broad mature and ripe proglottids it extends but a short distance within the vitellaria. The ratio of its length to the breadth in mature proglottids is about 1:6, in ripe pro- glottids about 1 :5 or 1 :5.5, in the ripest proglottid observed about 1 :4. Schwarz states that the cirrus-pouch is about 0.33 mm. long. The ductus ejaculatorius (Fig. 109) has numerous coils. The unprotruded cirrus is broad and muscular. The writer has not seen it protruded and no other investigator reports having seen it thus. An examination of Marotel's figures which have been reproduced (Figs. 197, 198) shows fewer coils of ductus ejaculatorius and of vas deferens than do the drawings of the writer (Figs. 109, 110). This can be explained by the assumption that Marotel could not follow these structures out com- pletely in his preparation which he states was made from material in a poor state of preservation. The material upon which the writer worked was in a fair state of preservation and in preparations made from it these ducts could be traced with ease. The vagina at its distal end is broad, measuring 0.09-0.12 mm., a breadth due in part to the breadth of its lumen and in part to the thickness of its sphincter vaginae. In this region the vagina is nearly as broad as is the cirrus in its basal portion. In its course to the middle of the proglottid the vagina never crosses the cirrus-pouch. Arrived at the middle of the segment it bends sharply and takes a sinuous course posteriad to the interovarial space which it enters after passing over the dorsal side of the ovary, not the ventral as Marotel figures it. There are no coils of the vagina anterior to the ovary. A receptaculum seminis has not been observed tho from its occurrence in other species in the genus its presence in this species may be inferred. The lobes of the ovary in nearly mature proglottids are more slender and more pointed at the extremities than in mature and ripe proglottids. In well 236 ILLINOIS BIOLOGICAL MONOGRAPHS [236 elongated segments the lobes of the ovary assume the form figured by Marotel (Figs. 197, 198). The vitellaria are lateral, and made up of small follicles. The vitelline ducts cross the ventral surface of the ovary instead of lying some distance anterior to it as Marotel figured them. In mature pro- glottids the uterus is a median tube. The early development of the lateral pouches (Figs. 110, 198) may be traced as small somewhat excentric bulbous enlargements of the median tube. This is not essen- tially different from 0. filaroides and 0. perspicua. These enlarge- ments may attain some size before any uterine eggs appear. In early stages there is considerable resemblance to the condition shown in Mar- otel 's figure (reproduced Fig. 198) of the ovigerous segment of 0. calmettei. Later, how^ever, many of these pouches (Fig. 109) extend toward the sides and the uterus resembles that of other species of the genus. The walls of these pouches are not very easily observed so Marotel may have overlooked them in his specimens. The pouches number 24-35 on either side. Two to four or five ventral uterine pores were observed in some of the riper proglottids. The uterine eggs in the alcoholic material are surrounded by three membranes. The outer- most very thin hyaline membrane measures from 0.024 to 0.026 mm. The second, a thick and homogeneous membrane, measures 0.022 mm. The inner membrane is thick, granular and more or less irregular in outline. It measures 0.014 mm. while the six-hooked embryo measures 0.012 mm. in diameter. Marotel (1899) states that the eggs are globular, with two membranes, the outermost one being thin and membranous, 0.065 mm. in diameter, and the ,other, a homogeneous and somewhat thick membrane, 0.024 mm. in diameter. This membrane corresponds in size and description to the one which the writer calls the middle membrane- He further states that the embryo is granular but does not give its dimensions. This species varies from the 0. racemosa described by Schwarz (1908) in the much larger size of the head, the larger size of the suck- ers, and the relative prominence of the same. The number and arrange- ment of the testes are radically different. In the length of the cirrus- pouch, in the number of coils of ductus ejaculatorius they differ greatly. In the size of the distal end of the vagina there is considerable differ- ence. The character of the diverticula of the uterus is not the same. In this species the uterus extends back to the ovary while in 0. race- mosa as described by Schwarz it does not. The vitellaria are much alike in character. This species is much smaller than 0. grandis. The heads are of about the same size but not alike in shape. The relations of cirrus, cirrus-pouch and vagina are different. There is a wide differ- 237] PROTEOCEPHALIDAE—LA RUE 237 ence in the number of testes and in the number of uterine outpocketings. The hosts and geographical distribution are also widely different. It varies from 0. marenzelleri in having a much smaller head, smaller suckers and in the lesser prominence of the same, in its smaller proglottids and in its smaller number of testes. The relations of the cirrus and cirrus-sheath are quite different. The fact that the vagina lies usually posterior to the cirrus-pouch in 0. marenzelleri constitutes a marked difference. The shape of the ovaries is somewhat different. In 0. marenzelleri the marked bending of the vagina in its course to the middle of the proglottid is very unlike the condition in this species, 0. calmettei is larger than 0. trimeresuri. It has a larger head, larger suckers and more than twice as many testes. The relations of the unprotruded cirrus and the cirrus-pouch are much alike in the two species. 0. calmettei is so much larger than 0. perspicua, 0. nattereri or 0. pigmentata that any possibility of confusion with them is pre- cluded. It is likewise much larger than 0. filaroides and 0. lonnhergiii which occur in amphibians. 0. calmettei most nearly resembles 0. grandis, 0. ma,renzelleri and 0. trimeresuri which likewise occur in the Crotalinae. OPHIOTAENIA PUNIC A (Cholodkovski) [Figs. 153, 187, 188] Taenia punica Cholodkovski 1908:418-20 1908 1910 1911 Proteocephalus punicus Hall 1910:148 Ophiotaenia punica La Rue 1911 :481 Specific Diagnosis: Characters of genus. Length as much as 10 cm. Breadth up to 2.75 mm. Head large, 1.5 mm. broad, unarmed, somewhat tetragonal in shape. Suckers four, large, round, 0.7 mm. in maximum diameter. Sucker musculature heavier on inner half. Necft short. Segmentation not evident. Proglottids attached by full width. First proglottids broader than long, older ones quadrate and finally longer than broad. The genital opening alternates irregularly, is situate near middle of proglottid margin. Testes very numerous, about 200, situated in two well defined lateral fields. Cirrus-pouch slender, ex- tending 1/4 to Ys across the breadth of the proglottid. Lobes of ovary long, slender, rough in outline, connected by a long slender mid-piece. Vitellaria lateral, composed of small follicles. Uterus median. Eggs not observed. Cholodkovski (1908:418-420) reported this species from a dog in Tunis (Island of Dscherba). Since this is a peculiar host in which to 238 ILLINOIS BIOLOGICAL MONOGRAPHS [238 find a species normally occurring in a lower vertebrate his description is here quoted omitting only the first and last paragraphs: "Nicht ohne tlberraschung habe ich also in einer mir von Dr. M. Weinberg zugesandten Tanie aus dem Darme eines Hundes eine neue Species erkannt, die ich hier in aller Kurze beschreiben will. Das Material (in Formol aufbewahrt) stammte aus Turtis (Insel Dscherba) und bestand aus drei unvollstandigen Stro- biiae, deren grosste eine Lange von etwa lo cm erreichte. Der Scolex ist sehr gross (1.5 mm breit), unbewaflFnet, mit vier starken rundlichen Saugnapfen und einer kleinen Erhohung auf dem Scheitel versehen. Die Saugnapfe sind etwas asymmetrisch gebaut, indem ihre innere Halfte merklich dicker als die aussere ist; der grosste (aussere) Durchmesser derselben betragt 0.7 mm. Gleich hinter einem sehr kurzen Halse wird die Strobila etwa 2 mm., dann bis 2.75 mm. breit, nach hinten aber allmahlich etwas enger. Eine aussere Gliederung ist auf ganzen Stucken unbemerkbar und lasst sich erst auf gefarbten Balsam— oder Glyzerin- praparaten in der Gestalt von sehr schwach ausgesprochenen Querrinnen kon- statieren. Die ersten Proglottiden sind breiter als lang, (vide Fig. 188 which is reproduced from Cholodkovski's figure 3) dann werden sie allmahlich langer, qu^jdratisch und endlich langer als breit; in keinem der mir vorgelegenen Exem- plare waren aber ganz reife; d. h. fertige Eier enthaltende Proglottiden vorhanden. Die Geschlechtsoffnungen alternieren unregelmassig. Die stark in der Querricht- ung verlangerten Ovarien liegen dicht an der hinteren Grenze der Proglottis, der Dotterstock ist sehr klein, der Uterus bildet einen geraden, in der Mittellinie der Proglottis nach vorn verlaufenden Stamm. In voUig reifen Proglottiden treibt er vielleicht auch laterale Zweige, in meinen Exemplaren war er aber immer einfach (vide Fig. 187 reproduced from Cholodkovski's figure 4). Die zahlreichen Hoden liegen in zwei lateralen Langsfeldern nach innen von den grossen Excre- tionsgefassen. An der Stelle letzteren befindet sich in totalen, mit Boraxkarmin tingierten Praparaten der reifsten mir vorgelegnen Proglottiden eine kornige Masse, deren Bedeutung mir unklar geblieben ist, da ich aus Mangel an Material keine darauf bezuglichen Schnittserien verfertigen konnte. "Da die hier beschriebene Tanie allem Anschein nach eine neue Species darstellt, so schlage ich vor, sie nach ihrem Fundorte Taenia punica zu nennen." This species was overlooked by the writer until his attention was called to it by Hall's article (Hall 1910) in which it is stated that the species belongs to the genus Proteocephalus, The paragraphs (Hall 1910:146 and 148) in which he gives his reasons for this belief are here quoted: "In compiling a key to the dog tapeworms, an examination of Kholodkovski's (1908) description and figures of Taenia punica from the dog showed that the cestode in question probably belongs in the genus Proteocephalus Weinland. The head, the uterine stem, the position of the ovaries at right angles to the uterine stem, and the position of the testes and the genital canals all indicate this. The granular strand of uncertain nature which Kholodkovski noted in the position of 239] PROTEOCEPHALIDAE—LA RUE 239 the excretory canals can hardly be anything other than the vitellaria, in the loca- tion usual for the species of the genus Proteocephalus. Kholodkovski states that the vitellarium is very small, but it seems likely that he has mistaken something else for the vitellarium. A comparison of the figures with mounted specimens of the worms of the genus Proteocephalus leaves no reasonable doubt on this point, and it is the opinion of the writer and Dr. B. H. Ransom, with whom the point was discussed, that it is more likely that the dog from which the tapeworms were obtained had just eaten the true host, some fish, reptile, or batrachian, than that the dog was the true host by virtue of a normal, even though unusual, infection with larval form. Fuhrmann appears to have overlooked the unusual features of this worm in his review of Kholodkovski (1909), and states that the anatomy is that of species of Taenia." "Taenia punica Kholodkovski, 1908, should therefore be known as Proteoceph- alus punicus (Kholodkovski, 1908) Hall, 1910, a combination proposed here for the first time " La Rue (1911:481) included this species in the genus Ophiotaenia. After making a careful study of Cholodkovski 's description and drawings, and after comparing them with many specimens of Proteo- cephalidae the writer agrees with Hall that the normal host of this species is not the dog. In the writer's opinion the true host is a snake. This cestode having its testes in two fields does not resemble any of the species of Proteocephalus thus far described from fish. The Proteoceph- alids that infest the lizards belong to the genus Acanthotaenia and these are distinguished from other Proteocephalids by the presence of spines on the head and neck. The Proteocephalids thus far described from Amphibia are small with rather small heads. Their genital organs, however, resemble those of Taenia punica. It is also true that in this respect they agree with the Proteocephalids of snakes. The species from snakes vary in size from small to large. Some of the species have large heads with large and prominent suckers. Their genital organs much resemble those of Taenia punica. As in the latter species the vitellaria of the Proteocephalids of snakes are sometimes composed of small follicles which refuse to take the stain well. In such cases it is easy to overlook the vitellaria. As an instance of this might be men- tioned the Taenia eunectes A. J. Smith in which the coils of the ducts in the interovarial space were thought to be the vitellaria. For these reasons and also on account of the size of the head and strobila the writer suggests that the true host of Taenia punica is a snake, and that Taenia punica belongs to the genus Ophiotaenia and should therefore be known under the name Ophiotaenia punica (Cholodkovski, 1908) La Rue. 240 ILLINOIS BIOLOGICAL MONOGRAPHS [240 1898 1908 1911 OPHIOTAENIA MARENZELLERI (Barrois) [Figs. 37, 199] Ichthyotaenia marenzelleri Barrois 1898 :2-3 Ichthyotaenia marenzelleri Schwarz 1908:26-27 Ophiotaenia marenzelleri La Rue 1911:481 Specific Diagnosis: Characters of genus. Observed length of stro- bila as much as 40 cm. Maximum breadth 1.5-2.0 mm. Scolex large, round, muscular, 1.2-2.0 mm. broad, well set off from neck. No rostel- lum. No hooks. No functional fifth sucker. Suckers four, 0.60-0.70 mm. in diameter. Neck not observed. Strobilation distinct. Proglot- tids closely attached. Length of proglottids as much as 5.5 mm., maxi- •mum breadth of same 1.5-2.0 mm. Excretory system composed of two pairs of lateral vessels. Genital organs as in genus. Genital aperture marginal, irregularly alternating, situated near middle of lateral mar- gin of proglottid. Testes numbering 150-200-240, measuring 0.06-0.07 mm. in diameter, situated in two lateral fields. Cirrus-pouch large^ extending about one-third across the proglottid breadth. Cirrus, when protruded, swollen at base and filiform at tip, 1 mm. long. Vagina usually posterior to cirrus-pouch. Uterus when completely developed possessing 20-25 lateral outpocketings on either side. Eggs provided with two membranes. Diameter not known. Habitat: In intestine of Ancistrodon piscivorous Holbr., southern United States. Barrois (1898) in a very brief description, unaccompanied by drawings, proposed this species. Schwarz (1908:26-27) redescribed this species using Barrois 's material. His description was accompanied by three drawings. La Rue (1911:481) included this species in the new genus Ophiotaenia. The material which Barrois and Schwarz had for study was col- lected by Doctor Calmette, Dec. 22, 1897, from Ancistrodon piscivorous Holbr., a snake indigenous to the southern United States. Unfortu- nately specimens of this species could not be had by the writer for study hence the data used in the following description are derived only from the articles of Barrois (1898) and Schwarz (1908). A study of 241] PROTEOCEPHALIDAE—LA RUE 241 new material is desirable in order that a more complete knowledge of this form may be had. This is one of the largest of the species of Ophiotaenia. The ob- served length is about 40 cm. Schwarz (1908:26) thought that perhaps the length might exceed that of 0. calmettei (35-80 cm.). The maxi- mum breadth observed was 1.2-2.0 mm. The scolex is large, round and muscular. It has a breadth of 1.5-2.0 mm. Barrois described an un- armed rostellum. Schwarz found no rostellura, nor does his delineation of the head, which is reproduced (Fig. 37), show such a structure. The scolex is clearly set off from the neck. The four suckers are muscular, prominent and nearly circular. They measure 0.60-0.70 mm. No func- tional fifth sucker is present. The neck was not described by Barrois or by Schwarz. The strobilation is distinct, altho the strobila has no indentations. Proglottids are strongly attached. The length of the largest proglottids is about 5.5 mm. and the maximum breadth about 1.5-2.0 mm. The excretory system is made up of two pairs of lateral vessels, a dorsal and a ventral. The genital aperture is marginal and it alternates irregularly. It is situated about the middle of the proglottid. The testes (Fig. 199) lie in two well marked lateral fields between the vitellaria and the uterus. Barrois gives 230-240 as their number, Schwarz 150-200. They measure 0.060-0.070 mm. Of the cirrus-sheath and vas deferens Schwarz says "the relation of the cirrus-sheath and vas deferens is especially characteristic for this form. In ripe segments the greater part of the cirrus-sheath is completely evaginated. There seems to exist a special muscular apparatus which withdraws the cirrus-sheath, when completely sexually mature, from the proglottid, so that it pro- jects free from the margin. In young segments it lies in its normal position within the segment". Schwarz has evidently misinterpreted the appearance in this case. His own drawings show no evagination of the cirrus-pouch but a com- plete evagination of the cirrus which is thick at the base, and filiform at the tip. From this heavy base the ductus ejaculatorius runs straight through the now greatly shrunken cirrus-pouch. There are some coils of the ductus ejaculatorius within the basal part of the cirrus itself. The writer has observed this condition in 0. trimeresuri. Schwarz states that the cirrus is about 1 mm. long in 0. marenzelleri. In his drawing the cirrus-pouch extends about % across the proglottid breadth. The vas deferens forms a mass of coils before entering the cirrus-pouch. The vagina opens usually posterior to the cirrus-sheath. Its course to the middle of the proglottid forms an arc. At the middle of the proglottid it bends sharply posteriad and then its course is direct to 242 ILLINOIS BIOLOGICAL MONOGRAPHS [242 the interovarial space. The uterus is a median tube from which arise on either side many lateral pouches; 20-25 are figured in Schwarz's drawing. The ovary is relatively large and its lobes are somewhat wing-like in shape. The eggs are provided with two membranes. No processes arise from the outer one. No measurements of the eggs were given by Barrois or Schwarz. The species is clearly differentiated from the other large species of the genus by the size and shape of the head and suckers. The relations of the cirrus and cirrus-pouch vary greatly from the plan common to the other large species of the genus. 0. trimeresuri which has the same relations of cirrus and cirrus-pouch is considerably smaller. 0. grandis resembles it in having the same host species and in being of large size. 0. grandis has, however, a very much smaller head which is not readily distinguished from the strobila. It has much smaller suckers and greatly different relations of cirrus and cirrus-pouch. Its cirrus is short and thick. It also has very many more uterine outpocketings. 0. marenzelleri is not to be mistaken for 0. racemosa, 0. imttereri, 0. pigmentata, or 0. perspicua on account of its much larger size. 0. fla- roides and 0. lonnhergii being from Amphibia and also being much smaller cannot be confused with 0. marenzelleri. OPHIOTAENIA GRANDIS La Rue [Figs. 38, 97-101] 1911 : Ophioiaenia grandis La Rue 1911 :481 Specific Diagnosis: Characters of genus. Body very long (frag- ments 200 mm.) by 2.75-4.25 mm. broad in region of ripe proglottids. Neck 5-8 mm. long. First proglottids much broader than long; pro- glottids with developing sexual organs quadrate or nearly so; ripe proglottids quadrate or much longer than broad. Head large, 1.0-1.2 mm. broad at base of suckers. No fifth sucker or rostellum, no hooks. Suckers nearly circular, deep and muscular, measuring about 0.34 by 0.36 mm. Genital aperture marginal, irregularly alternating, situated near middle of proglottid. No genital papilla but sometimes a deep depression about genital pore. Testes large, numerous, 200-250 in num- ber, arranged in two broad lateral fields. Cirrus-pouch 0,24-0.26 mm. broad, 0.64-0.75 mm. long, length equal to V^-Vs of proglottid width. Cirrus short and heavy. Few or no coils of ductus ejaculatorius in cirrus-pouch. Vagina anterior or posterior to cirrus-pouch. Sphincter vaginae heavy. Uterus with 40-60 lateral outpocketings on either side. 243] PROTEOCEPHALIDAE—LA RUE 243 Ventral uterine openings 2-8 in number. Outer egg membrane ellip- soidal, 0.026 by 0.037 mm. or sometimes spherical 0.032 mm. in diame- ter; second egg membrane 0.021-0.023 mm. Embryos 0.015-0.016 mm. Outer membrane smooth. Type: Specimens in collections of United States Bureau of Ani- mal Industry, No. 14854. Habitat: In intestine of Ancistrodon piscivorous Holbr. (type host). National Zoological Park. The locality from which this host came is not known. The species is found only in North America. La Rue (1911:481) described this species in a preliminary way. Six or eight heads together with numerous pieces in a bottle bearing the U. S. Bureau of Animal Industry number 14854 were labelled "Ichthy- otaenia: host Ancistrodon piscivorous; location, intestine; locality Nat. Zoo. Park, collected S. S. Shawhan. Nov. 18, 1907." These were secured for the writer's study by Professor "Ward. No complete worm was found. The largest piece was 200 mm. long and 3.5 mm. broad at the anterior end and 4.25 mm. broad at the posterior end. This piece was made up of proglottids that were well advanced in development, being nearly mature at the anterior end and nearly ripe at the posterior end. The younger proglottids were not distinctly separated by furrows but the more mature ones showed very evident segmentation. Judging from the size of the segments and their state of development it seems likely that the whole worm would attain a length of 300-400 mm. or perhaps even more. Like other species of Ophiotaenia the body is quite flattened. However, the body is thicker than has been observed by the writer in 0. calmettei, 0. nattereri, 0. trimeresuri, 0. perspicua, and Crepidohothrium gerrardii. The head (Fig. 38) is large tho not so large as in 0. marenzelleri (Barrois) or Crepidohothrium gerrardii (Baird). It measures 1.0-1.2 mm. in diame- ter at the base of the suckers. The scolex, measured from its tip to the base of the suckers has a length of 0.50-0.60 mm. There is no rostellum, no hooks, no fifth sucker, and from toto mounts no vestigial fifth sucker may be observed. As yet no sections of the head have been made. The four deep suckers are borne on the broadest part of the head and these are directed outward. They are not prominent, are strongly muscular, nearly circular in outline and they lack the upward pointing projection that is always found in the suckers of C. gerrardii. The suckers measure 0.34-0.35 mm. in transverse axis by 0.35-0.36 mm. in longitudinal axis. The cavity of the sucker is deep. Its open- ing measures 0.15-0.17 mm. in longitudinal diameter by 0.20-0.22 mm. in transverse diameter. Immediately back of the head there is some- 244 ILLINOIS BIOLOGICAL MONOGRAPHS [244 times a large inflation (Fig. 38). Since this is not always present it must be due to the contraction of the heavy longitudinal muscles of the upper part of the neck. The neck itself is broad, thin and long, being 0.85-1.0 mm. broad by 4-8 mm. long. The first proglottids are short, their breadth equalling several times the length. As the proglottids become older the shape changes from the rectangular to nearly quadrate or quadrate. Proglottids ranging in age from nearly mature to ripe are usually longer than broad. Those proglottids which show the beginnings of the cirrus-pouch and vagina measure 0.5 mm. long by 1.0 mm. broad while those in which the anlagen of the testes are appearing measure 0.680 mm. long by 0.850 mm. broad. Both length and breadth increase greatly as the segments near maturity. A few nearly ripe proglottids are broader than long, measuring 3.25 mm. long by 4.25 mm. broad. The longest proglottid found measured 8 mm. long by 2.75 mm. broad while many proglottids measure 3-5 mm. long by 2-3 mm. broad. The surface of the body is somewhat wrinkled, due perhaps to having lain twisted for a long time in the alcohol. There seem normally to be no furrows either longitudinal or transverse. Pro- glottid limits are not well defined in young proglottids but are well defined in the older ones. The genital aperture is marginal, irregularly alternating. Fre- quently the aperture occurs on the same side in several successive pro- glottids but always in greater numbers on the left side. The greatest number of genital apertures found occurring successively on the left side was ten. No papilla marks the genital aperture. Indeed in many proglottids the muscles are so contracted about the genital aperture as to cause a deep depression (Fig. 100). In such cases it is noteworthy that the cirrus and vagina open to the exterior separately. In many cases it is doubtful if a true genital sinus exists. If present it is ex- tremely shallow. The arrangement of the sexual organs agrees in general with that of other Proteocephalids. The cirrus-pouch (Figs. 97, 98) is short and broad, and is broadest at the distal end. It is either straight or curved, depending upon the state of contraction of the proglottid and of the muscles in the region of the genital aperture. When the region of the genital aperture is depressed the cirrus-pouch is usually somewhat bent (Fig. 100). Its length is 0.64-0.75 mm. and its breadth 0.24-0.26 mm. The ratio of its length to the breadth of the proglottid is 1 :3 or 1 :5. The cirrus (Figs. 97, 98) when protruded is thick, short, straight and heavily muscled. It is continuous with the ductus ejaculatorius which forms no, or at least few, coils within the cirrus-pouch. The drawings (Figs. 97, 98) show only a slight twist or turn in this part of the ductus. This descrip- 245] PROTEOCEPHALIDAE—LA RUE 245 tion and an examination of the figures makes it evident that the cirrus and cirrus-pouch of the present species are very different from the same organs in 0. marenzelleri with which this species is closely allied. In that species there are many coils of the ductus ejaculatorius within the cirrus-pouch, and the cirrus when protruded is thick at the base but drawn out to a slender tip. Schwarz (1908) errs in saying that the cirrus-pouch is evaginated in 0, marenzelleri. His own figures show the cirrus-pouch in situ. In the present species the vas deferens is thrown into numerous coils which serve as a vesicula seminalis. There are about 200-250 testes which are arranged in two lateral fields. The testes measure 0.04-0.05 mm. broad by 0.075-0.100-0.125 mm. long. The vagina opens to the exterior either anterior or posterior to the cirrus-pouch, with almost equal frequency. Out of 45 proglottids examined on this point the vagina in 21 cases opened anterior and in 24 cases posterior to the cirrus-pouch. A heavy sphincter vaginae 0.095 mm. long by 0.150 to 0.160 mm. broad, including vagina, surrounds the vagina near its opening to the exterior. The thickness of the sphincter alone is 0.040-0.070 mm. The vitellaria are follicular in structure, and lateral in position. Each follicle measures about 0.015 by 0.030-0.035 mm. A diagram (Fig. 99) made from a toto preparation shows that the arrange- ment of the organs of the interovarial space is similar to that figured for other Proteocephalids. The ovaries are thin dorsoventrally. The mid-piece connecting the ovarian lobes is slender and long. The uterus (Fig. 101) in maturing proglottids is a median ventral tube. From this are developed 40-60 lateral pouches on either side. These are formed by the method already described by La Rue (1909) for 0. filaroides. No eggs are passed into the uterus until the outpocketings have attained a considerable size. Two or more preformed ventral uterine pores are developed before many eggs are present in the uterus. The largest number of the uterine pores in the material studied was eight. The eggs taken from the uterus of alcoholic specimens are usually ellip- soidal, measuring about 0.026 by 0.037 mm. over the outer membrane. Spherical eggs measure about 0.032 mm. The second membrane is spherical, 0.021-0.023 mm. in diameter. The third membrane closely invests the embryo which is 0.015-0.016 mm. in diameter. Mature eggs have smooth contours. There are no booklets or holding organs on the egg membrane as Schwarz (1908) figures for the eggs of 0. natter'eri (Parona). The present species differs from 0. marenzelleri (Barrois) in hav- ing a smaller head, smaller suckers, larger proglottids, greater breadth, more numerous testes and more numerous uterine pouches. The char- acter of the evaginated cirri of the two species is very different. It also 246 ILLINOIS BIOLOGICAL MONOGRAPHS [246 differs from Crepidobothrium gerrardii (Baird) in the size of the head and suckers, and in the character of the latter. 0. grandis has a long unsegmented neck while C. gerrardii has almost no neck. 0. grandis somewhat resembles 0. calmettei in the size of the head and suckers. It differs from that species in the size of strobila and of proglottids, and in length of neck. 0. grandis has a larger number of testes and a cirrus which differs greatly from that of 0. calmettei. 0. grandis is so much larger than 0. perspicua, 0. nattereri (Parona), 0. irimeresuri (Parona), and 0. racemosa (Rudolphi) that a possibility of confusing it with any of those species is precluded. CREPIDOBOTHRIUM GERRARDII (Baird) [Figs. 12, 13, 33, 34, 42, 111-115, 123, 124, 190, 196] 1850: Taenia racemosa Diesing 1850:511, in part 1860: Tetralothrium gerrardii Baird 1860:446-448 1861: Tetralothrium gerrardii Baird 1861:228-230 1864: Tetrahothrium gerrardii Diesing 1864:82 1898: Ichthyotaenia gerrardii Liihe 1898:652 1899: Crepidobothrium gerrardii Monticelli 1899:9-25 1899: Ichthyotaenia gerrardii Liihe 1899:525 1905: Taenia racemosa Shipley 1905:101 1908: Taenia eunectes Smith 1908:39-41 1911 : Crepidobothrium gerrardii La Rue 1911 :479-480 Specific Diagnosis: Characters of genus. Length of strobila as much as 45.6 cm. Maximum breadth 0,85-2.00 and even 6.0 mm. Stro- bila flat, thin and wrinkled. Proglottids closely attached. Segmentation indistinct. Head large, tetragonal, pyramidal, maximum breadth of same 0.935-1.3 or even as much as 1.75 mm., thickness a little less than breadth, length about 0.68-0.90 mm. Fifth sucker vestigial but with cavity open to exterior. Four suckers prominent, muscular, cordate, with lower margin interrupted and re-entrant into sucker cavity. Breadth of suckers 0.40-0.70 mm. Neck broad, not over 0.5-0.8 mm. long. First proglottids short, rapidly increasing in length. Mature proglottids quadrate. Ripe proglottids longer than broad. Length of same 1.7-2.3 mm. by 0.65-1.09 mm. broad. Genital pore marginal, irregularly alternating, situated near mid- dle of proglottid. Vagina anterior or posterior to cirrus-pouch. Open- ing of vagina dorsal to cirrus-pouch. Testes 200-400 in number, small, 0.035-0.050-0.080 mm. in diameter, situated in two lateral fields. Cirrus- 247] PROTEOCEPHALIDAE—LA RUE 247 pouch 0.23-0.5 mm. long by 0.10-0.15 mm. broad. Length of same 4-5-6 times into the proglottid breadth. Several coils of ductus ejaculatorius in cirrus-sheath. Lumen of vagina large near opening. Sphincter vaginae heavy. Receptaculum seminis present. Ovary posterior, bi- lobed, lobes thick, short, irregular. Organs of interovarial space as in Ophiotaenia. Vitellaria small, loosely follicular, lateral. Fully devel- oped uterus provided with 20-30 lateral pouches. Eggs possessing twb (?) or three membranes. Outer membrane measuring 0.085-0.100 mm., second, 0.028-0.030 mm., embryo 0.016-0.018 mm. in diameter. Habitat : snakes. In intestine of Boidae, a family of South American Host ( ?)Ophiomorphus miliaris Eunectes murinus (scytale) (?)Bothrops jararacca i?)Ophis merremii Boa constrictor Eunectes murinus Wagl. Eunectes murinus Locality South America South America South America Brazil South America Collector Natterer Edward Gerrard A. J. Smith Authority Diesing, 1850:511 Diesing, 1850 :5ri Diesing, 1850:511 Diesing, 1850:511 Baird, 1860:446-448 Shipley, 1905:101 (La Rue) Smith, 1908:39-41 (La Rue) In the discussion of the hosts of Ophiotaenia racemosa it was stated that Ophiomorphus miliaris and Ophis merremii were to be considered as probable hosts of that species. It is doubtful if they serve as the hosts of Crepidohothrium gerrardii. Bothrops jararacca is one of the Crotalinae and would not be likely to harbor C. gerrardii, but in aH probability it would be the host of a species resembling 0. marenzelleri, 0. grandis, 0. trimeresuri, and 0. calmettei. These form a group quite distinct from the other Ophiotaenia. It is very likely that Diesing being unable to make a careful examination of the cestodes of these snakes grouped them all under the name Taenia racemosa. It is desira- ble to re-examine the specimens to which Diesing 's description and notes refer, if they still exist. The hosts of C. gerrardii of which there is no doubt are Eunectes murinus "Wagl. and Boa constrictor L. This species was first reported by Diesing (1850:511) who called it Taenia racemosa Rud. His diagnosis agrees excellently with that of Crepidohothrium gerrardii. He includes as a host one of those species, 248 ILLINOIS BIOLOGICAL MONOGRAPHS [248 Eunectes murinus (scytale), from which this species has been reported several times. His description and habitat data are quoted in full: "Taenia raccmosa RUDOLPHI. Caput magnum tetragonum, acetabulis an- gularibus subterminalibus v. terminalibus, subovatis v. cordatis. Colluni nullum. Articuli supremi brevissimi, subsequentes longiores et latiores, angulis rotundatis, ultimi longi parallelopipedi angustiores. Penes fili formes basi incrassati, margi- nales vage alterni. Longit. 2" il4' ; latit. med. 1-3"'; ultim. i"'. "Taenia racemosa Rudolphi: Synops. App. 692. — Dujardin: Hist. nat. des Helminth. 610. "Habitaculum. Ophiomorphus miliaris, Martio. — Eunectes Scytale, Octobri, Februario et Junio. — Bothrops Mararacca (misspelling for jararacca), Martio et Aprili. — Ophis Merremii, Januario, in Brasilia (Naiterer) : in intestinis. M. C. V." Baird (1860:446-448) described this species which was found by Mr. Edward Grerrard in the intestine of a Boa constrictor from South America. Since the name Taenia racemosa Rud. had already been ap- plied to a different species of cestode the name suggested by Baird stands by reason of its priority. Baird 's second description (1861:228- 230) is a copy of the earlier description (1860:446-448). Because of the inaccessibility of either of these descriptions for many investigators the later diagnosis which alone was accessible is quoted : " The species now to be described, however, was found by Mr. Edward Gerrard of the British Museum ... in the intestine of a Boa constrictor from South America. "The head is large, tetragonal; the four bothria disposed crosswise, joined by the margins ; each of them large, round, and having on one side a strong ridge. Body depressed, narrow, articulated. No distinct neck. Anterior extremity of body very narrow, and the articulations there are extremely small, becoming larger as they descend, the inferior being quadrangular and rather large. The margins of the articulations somewhat annulated, but having no appearance of genital apertures. The head is about three-fourths of a line broad ; but I could not discover any mouth. Apparently only fragments of these worms were ob- tained; but some of these detached pieces were about 18 inches in length. "Hab. Intestines of Boa constrictor." Diesing (1864:82) placed this species in the genus Tetrahothrium but with some reservation. His diagnosis is quoted in full in order that a comparison of it can be made with his diagnosis of Taenia racemosa, Diesing (1850:511) : "Tetrahothrium Gerrardii Baird. Caput magnum tetragonum, bothriis quatuor cruciatim oppositis subcircularibus magnis, marginalibus contiguis, singulo costa 249] PROTEOCEPHALIDAE—LA RUE 249 1.) Os. . . . Collum nullum. Corpus depressum augustutn, articulis su- premis angustissimis, posterioribus quadrangularibus. Aperturae genitalium .... Longit. fragment! i8", latit. capit. Ya". "Habitaculum. Boa Constrictor: ex America meridionali, in intestinis (Ger- rard)." A comparison of the diagnosis just quoted and the earlier one by Diesing (1850:511) leaves no doubt that the two diagnoses concerned the same species, namely, Crepidobothrium gerrardii. Liihe (1898:652) included this species in a list of Ichthyotaenia from snakes. He gave no reason for considering it a member of this genus. Fuhrmann (1899 : 864) in a footnote made this statement concerning this species: "Liihe, M., Oochoristica nov. gen. Taeniadarum. (Zoolog. Anz. 1898. No. 576) giebt an, dass T. Gerrardii (Baird) in das Genus Ichthyotaenia gehore; dies ist aber wie mir Prof. Monticelli mitteilte und wie ich mich selbst an den von ihm nach den originalen angefertigen Zeichnungen uber- zeugen konnte, keineswegs der Fall. Es gehort diese Form in ein beson- deres Genus, das Prof. Monticelli demnachst unter dem Namen Crepi- bothrium publizieren wird." During the same year Monticelli (1899: 9-25) made a report, accompanied by drawings, upon the type material of this species which was in the British Museum. He also studied some material which had been sent to him by Prof. Fr. Bell. As a result of this study he erected the genus Crepidobothrium for Baird 's species alone. Liihe (1899:525) in a footnote discussed the position of this species which he still maintained belonged to the genus Ichthyotaenia. His ground for this belief was that the head and suckers which are different from those of other Ichthyotaenia constitute only a specific difference. He stated that the name Crepibothrium (Fuhrmann 1899) was a nomen nudum. He had not seen Monticelli 's article and so was in no position to judge Monticelli 's work. Shipley (1905:101) made the following report of this species: ''Taenia racemosa Rud. Diesing, Syst. Helm. I. p. 511. Many speci- mens from Eunectes murinus Wagl., it has also been described from the intestine of Bothrops jararacca "Wagl." Thanks to Professor H. B. Ward who secured them for study, the writer has been able to examine some of Shipley's specimens from the host Eunectes murinus. They were probably from the same lot which Shipley recorded in the above quotation. They proved to belong to the species Crepidobothrium ger- rardii (Baird). Smith (1908) found some cestodes in an anaconda, Eunectes murinus. He described them under the name Taenia eunectes. "1) "Each of them large, round and having on one side a strong ridge" Baird 1. c." (Baird :i86o or i86i). 250 ILLINOIS BIOLOGICAL MONOGRAPHS [250 Upon request Doctor Smith sent some of this material to Professor Ward who has very kindly permitted the writer to study it. Study of this material has shown that it belongs to the species Crepidohothrium gerrardii. La Rue (1911:479-480) gave the synonymy of this species briefly and stated some of his findings. A comparison of the diagnoses of Diesing (1850:511 and 1864:82) with the description by Baird (1861) and with the description by Monticelli (1899:9-25) leaves no ground for doubt that these investi- gators were reporting the same species. In certain respects the descrip- tion by Smith (1908:39-41) differs radically from that of Monticelli. However an examination of Smith's material has shown that Smith made numerous misinterpretations which are the cause of the apparent discrepancies between his work and Monticelli 's. In his study of this form the writer has found Monticelli correct in the main. It has al- ready been stated that Shipley's material belonged to C. gerrardii. The question concerning the correct name for this species must be settled. From a structural point of view this species cannot be retained in the genus Taenia nor in the genus Tetrabothrium. Anatomically this species is one of the Proteocephalidae. This has been recognized by Liihe (1898), Fuhrmann (1899), and Monticelli (1899). The name which Fuhrmann (1899:864) gave for it can be dismissed as a nomen nudum. Liihe (1898 and 1899) considered that the species belonged to Ichthyotaenia. It has already been shown in the discussion of the genus Proteocephalus that the name Ichthyotaenia Lonnberg (1894) is a syn- onym of the name Proteocephalus Weinland (1858) and hence cannot be retained. The latter name also antedates the name Crepidobothriura Monticelli (1899) and on that account should be used in place of Crepi- dobothrium if structurally Baird 's species shows sufficient agreement with Taenia filicollis (amhigua) Rud. the type of Proteocephalus. An examination of Monticelli 's (1899) description and figures and of the writer's description with its accompanying figures, shows conclusively that this species does not agree anatomically with the type of Proteo- cephalus and that this species really belongs to a different genus. The only available name is Crepidohothrium Monticelli (1899) which is not invalidated by the name Crepibothrium as used by Fuhrmann and which was unaccompanied by a diagnosis, since the word Crepibothrium is not a homonym of Crepidohothrium. Liihe 's objection therefore is not valid. One bottle of 9 specimens with heads, labelled ^^Ichthyotaenia Gerrardii (Baird) ? aus Eunectes murinus intestinum Berlin Aquarium" was received from Dr. Anton Collin, Berlin, in answer to a request from Professor Ward. This is now No. 10.179 in Professor Ward 's collection. 251] PROTEOCEPHALIDAE—LA RUE 251 One bottle of 5 specimens with heads and some pieces, labelled ' ' Taema racemosa Rud from Eunectes murinus." was received from A. E. Ship- ley, Cambridge. The material is now No. 08.472 in Professor Ward's collection. One bottle of 3 specimens with heads, labelled ^'Taenia Eunectes from Anaconda, sm. Intestine, Phila. Zoo. G. 939. U. P. Path- Hist. 1694," was received from A. J. Smith, Philadelphia. This is now No. 10.190 in Professor Ward's collection. Seven slides, one of them con- taining a head, labelled "No. 1858, From Boa Constrictor Box 53-20, 1893," were received for examination from the Bureau of Animal In- dustry, Washington. A careful study of the specimens thus brought together showed that they belonged to the same species. Since in each lot one or more heads were present a careful study of this organ could be made. For this purpose balsam mounts were made from some heads while others were cleared and examined in glycerine. On account of the small amount of material the section method was not used except in a single instance The results of this study are best shown in the accompanying table. The heads used for measurement were chosen quite at random, for an examination of the material showed that a tabulation of measurements of all heads was unnecessary. The dimensions are in millimeters. Lot number Source Preparation 1858 B.A.I, balsam 08.472 from Shipley balsam unflattened 08.472 from Shipley glycerine 10.179 from Anton Collin glycerine 10.179 from Anton Collin glycerine 10.190 from A. J. Smith glycerine T. eunectes Data from Smith (1908) Head Suckers breadth length breadth of two breadth length 1.360" o.68o± 0.646 0.646 1. 000 o.50o± 0.935' o.68o± 0.400 0.459 0.76s 0.680 1.090 o.68o± 0.646 1. 190 o.68o± 0.544 O.S44 0.402 0.850 1.090 o.68o± 0.510 1. 190 0.850 0.510 0.544 1. 190 0.500 1.300 0.900* 0.700 Neck 0.850 0.500 0.390 0.500 0.300 1.200' a) Head showed some eflfect of flattening in mounting. This may have some effect on measurements of suckers also. b) Head was evidently very strongly contracted as were also the suckers. c) Measurements were taken from Smith's drawing which was accompanied by a scale of magnification. A study of the above table shows that in the main the measure- ments agree very well. Where apparent discrepancies occur they are easily accounted for by states of contraction and compression. In every case the shape of the suckers is the same, due allowances being made 252 ILLINOIS BIOLOGICAL MONOGRAPHS [252 for contraction and relaxation. Every head of the four lots was exam- ined in this respect and in each sucker the lower margin was turned in thus ** forming an angular intrusion into the cavity of the sucker" as Smith (1908) described it. In the more contracted or in greatly ex- panded suckers this condition was somewhat difficult to make out but when properly cleared as in glycerine or balsam it was apparent. A study of toto preparations of the proglottids from the various lots fails to disclose any good characters for separating them. The writer therefore bases the following description upon this material so collected together, referring at times to special lots. He also uses the descriptions by Smith (1908) and by Monticelli (1899) as sources of comparative data. It was desired to study the slides upon which Monticelli based his description but unfortunately Professor Ward was unable to secure them. This is one of the largest of the Proteocephalid species inhabiting snakes. 0. calmettei (Barrois), 0. marenzelleri (Parona), 0. grandis are of about the same size. The latter even exceeds C. gerrardii in some measurements. Next smaller than the members of this group comes 0. racemosa (Rud.). A comparison of the table at the end of this report shows the size relationships of these species. The strobila varies considerably in length. According to Baird (1860) it measures 45.6 cm. (18 inches). Smith (1908) reports specimens 95-100 mm. long. Diesing (1850:511) gives its length as 2 inches to 11/^ feet. Monticelli gives no data on this point. The reported breadth varies from 0.85 mm. in some short specimens examined by the writer to 1.8 mm. in the B. A. I. slide 1858, to 2.0 mm. according to Smith, and 2.0-6.0 mm. (1-3 lines) in the middle to 2 mm. (1 line) at the posterior end, accord- ing to Diesing (1850). The strobila is flat and relatively thin. The surface is more or less thrown into folds. The proglottids are attached by their full width. The segmentation is indistinct in the anterior region and more distinct in the region of mature and ripe proglottids. In certain strobilas the segmentation is more distinct than in others. It is never as clearly marked as in some species of Proteocephalids. The head is large, readily distinguishable to the naked eye. Baird describes it in these words: "The head is large, tetragonal; the four bothria disposed crosswise, joined by the margins." Smith (1908) says of it, "The head, viewed from the front presents a crucial appearance from the prominence of the suckers, measuring transversely across the two opposed suckers 1.5 mm. and laterally across two adjacent suckers 1.3 mm The suckers, thus prominent, form the rounded arms of the crucial frontal picture, each sucker being globose in shape and having a lateral diameter of about 0.7 mm." Smith's figures of the 253] PROTEOCEPHALIDAE—LA RUE 253 hea4 are reproduced (Figs. 33, 34). Monticelli's (1899) description of the head reads: "Come si vede, il capo (Monticelli's figures of the head are reproduced in figures 123, 124) e abbastanza grande e ben distinto dal coUo che anteriormente si slarga di poco come pei sostenerlo : esso ha I'aspetto grossolano di un porno da bastone e, come si rileva dalla figura, e rigonfio e massiccio, tetragonale, a forma di piramide tronca. Anteriormente ristretto, cupuliforme, terminato nel mezzo da- un indistinto cocuzzoletto apicale conoide ; posteriormente slargato e v troncato sporge oltre il coUo per i suoi spessi margini rigonfi e presenta, nel mezzo di ciascuno dei quattro lati, una insenatura molto accentuata. ' ' The head is always tetragonal and somewhat pyramidal. This shape may be varied to some extent by the states of contraction. A head which is relaxed and whose suckers are expanded may have a lobate appearance (Fig. 13). Here deep grooves may be seen between the suckers. In greatly contracted heads (Fig. 12) the suckers are drawn closely together, the furrows between the suckers are almost obliterated and the suckers themselves are reduced in size. In such heads the suckers are seen to be directed forward while in the relaxed head the suckers are directed outward. These figures should be compared- with the drawings of heads by Smith (1908) and Monticelli (1899), which have been reproduced here (Figs. 33, 34 and Figs. 123, 124). These figures illustrate the various states of contraction which one meets in a study of considerable material. The dimensions of the head are: breadth 0.935-1.30 mm. in the writer's material, 1.75 mm. (Baird), thickness nearly equals breadth, length about 0.68-0.90 mm. The apex of the head is slightly elevated, rarely flat. There is no rostellum and no spines. From toto preparations no trace of a fifth sucker could be found but in a series of transverse sections of the head a small sunken fifth sucker was found which had degenerated until it had lost its radial musculature (Fig. 42). The sucker still possessed its opening to the exterior which measured 0.037 by 0.026 mm. and this opening led into a cavity but a little more than 0.03 mm. deep. The sucker measured about 0.048 by 0.067 mm. on its transverse axes. From the tip it ex- tended about 0.06 mm. into the head. This tissue was in bad condition. It took the stain poorly. Its nuclei were not visible either in the sucker or in the other parts of the head. Cell outlines were indistinct or lack- ing. The musculature of the sucker was irregular or perhaps no longer visible. There were however certain fibers which seemed to be muscles. A basement membrane was clearly visible and surrounding this on the outside were circular muscle fibers which could be readily distinguished by focussing on successive layers of tissue. The sucker cavity was filled 254 ILLINOIS BIOLOGICAL MONOGRAPHS [254 with a granular mass of unknown origin. The writer noted a similar granular material in the sucker cavities of degenerating suckers of Ophiotaenia filaroides. This sucker stands about midway between the vestigial sucker of 0. filaroides, O. lonnhergii and P. amhloplitis on the one hand and the functional fifth sucker of P. fallax, P. pinguis and P. percae on the other. Approximately the same stage of degeneration is shown in the drawing (Fig. 44) of a degenerating fifth sucker of the plerocercus of O. filaroides as is shown by the fifth sucker in C. gerrardii. Of the suckers Monticelli (1899) writes: "Non vi sono botridii, ma quattro ventose, grandi ovoidali, disposte in croce, secondo il loro asse tnaggiore, ai quattro angoli del capo ed obliguamente e con- vergenti verso il cocuzzoletto apicale. Esse sono approfondate nello spessore del capo e ne occupano quasi tuta la lunghezza; fra le ventose il capo si in fossa in piccoli solchi longitudinal che si terminano nelle insenature marginali innanzi ricordato. Le ventose hanno forma di ferro di cavalloe, diro meglio, ricordano la figura di un piede di cavallo ferrato visto di sotto. Esse hanno un aspetto carater- istico proprio, che puo facilmente ricavarsi dalla fig. 2 e, meglio ancora, dalla fig. 3, che mostra il capo visto di sopra ed alquanto schiacciato. Che il margine posteriore delle ventose non e integro, ma scavato da una insenatura formata dal ripiegarsi verso il mezzo del cavo di esse delle pareti posteriori della ventosa — che non formano un tutto continuo, ma sono posteriormente interrotte — che rav- vicinate fra loro, constituiscono una doppia cresta, breve, la quale si perde, divari- cando in due rametti a V, nel fondo della ventosa. Ma, meglio che dalla descrizione. puo intendersi la peculiare struttura di queste ventose, gia adombrata dal Baird, come si rileva dalle parole innanzi citate, dall' esame delle figure 2 e 3, che danno una fedele immagine della forma del capo del cestode in esame, come I'ho ricavata dallo studio del tipo originale del Baird." Monticelli 's figures above mentioned are reproduced (Figs. 123- 124). In these figures the point of the in turned margin is split and each arm of the "V" is turned out. Material examined by the writer shows no such spreading of the point of the "V". A series of tran- sections show that the point of the '*V" is closed. When the sucker is much relaxed the point is difficult to see, but it may be found if the head be cleared and examined in glycerine. Likewise in very strongly contracted suckers the intumed point may escape detection except when cleared and examined under favorable conditions. Prom an ex- amination of three heads from Smith's material the writer is led to believe that the narrow slit-like opening in the suckers as shown in his figures (reproduced Figs. 33, 34) is due to foreshortening. Usually the opening is much more nearly round than here shown. The suckers are very prominent, most prominent in a relaxed head (Fig. 13). They measure 0.40-0.70 mm. in breadth. The average is about 0.55 mm. 255] PROTEOCEPHALIDAE—LA RUE 255 A poorly defined neck region separates the head from the body. Baird (1860) says: "No distinct neck. Anterior extremity of the body very narrow." Monticelli (1899) says: "II collo e relativamente lunghotto e le prime proglottidi sono come delle rughe e molto indis- tinte." A. J. Smith (1908) gives a width of 0.300 mm. for the neck and his drawing shows a length of 1.20 mm. Measurements of Smith's material however gives a width up to 1.190 mm. Measurements of six strobilas give 0.5-0.85 mm. for the length of the neck, and in these cases it is probable that the measurements given are too great. The region of proglottid formation begins very close to the head and here the proglot- tids are very short and their boundaries poorly defined. The neck is thin and flat. The first proglottids are much broader than long. As they become older they increase rapidly in length. Mature segments are nearly quadrate while ripe proglottids are longer than broad. The moniliform proglottids, mentioned by Smith (1908), are not character- istic of the species but are due to contraction states. Among the three specimens which he sent to Professor "Ward was a short one which had these peculiarly contracted proglottids. The longest and most perfect specimens had no segments of this character nor were such proglottids observed among the specimens of the other lots. Ripe proglottids meas- ure 1.70-2.30 mm. in length by 0.65-1.09 mm. in breadth. The genital anlagen appear very early in the chain. In fact they are to be seen in all but the youngest proglottids. The genital aperture is irregularly alternating. It is situated near the middle of the margin of the segment. The vagina and the cirrus open into the common geni- tal sinus, the vagina being either anterior or posterior to the cirrus- pouch. A genital sinus can scarcely be said to exist. Under favorable circumstances the sinus may be seen to be 0.020-0.030 mm. deep. This shallow sinus is easily overlooked. The opening of the vagina is some- times dorsal to the cirrus-pouch but the writer is not prepared to say that it always occupies that position. Monticelli (1899) thinks that the vagina normally lies above the cirrus-pouch and that when it is found anterior or posterior to the same it has been displaced by pressure. From work on this species and also on several other species in which the vagina may lie in either the anterior or posterior position the writer is convinced that pressure has nothing to do with this variation. The preparations studied have all been made without compression, yet the vaginae alternate irregularly in position. Sections in a frontal plane through developing proglottids of 0. lonnbergii show the vaginae some- times anterior and sometimes posterior to the cirrus-pouch. They de- velop in those positions which they hold in mature and ripe proglottids. A careful examination of toto preparations of C. gerrardii and of sev- 256 ILLINOIS BIOLOGICAL MONOGRAPHS [256 eral species of Ophiotaenia shows that if the vagina is in an anterior position it extends farther anteriad before bending toward the genital pore than it does when it occupies the posterior position. If these vaginae are displaced by pressure then they ought to show evidence of such displacement by their form or structure. This they do not do, as an examination of the drawings (Figs. 111-115) will show. It will be noted that when the vagina is anterior to the cirrus-pouch it usually crosses the coils of vas deferens. In C. gerrardii the vagina, when anterior, never crosses the cirrus-pouch. The testes lie in two broad fields which tend to coalesce in the anterior region of the proglottid. Testes number about 240 in the specimens from the Bureau of Animal Industry. Montieelli (1899) found about 200 or more in each proglottid. Smith (1908) figures but 87 testes. There must be an enormous variation in the number of testes or else Smith overlooked some of them, for in a preparation of an immature proglottid from one of his specimens the writer counted nearly 400 testes. In this proglottid, delineated (Fig. 113), the testes are very small. In maturity many of them might be crowded down to a lower plane and so might be overlooked. However, in his prepara- tions the writer has not found evidence for this crowding. There is no evidence that any of the testicular anlagen fuse together or degenerate. As a rule the testes in this species measure 0.030-0.050 mm. in diameter but in a specimen from lot 10.179 the testes measured as much as 0.080 mm. Montieelli (1899) says that they are about twice the size of the vitelline follicles. The vas deferens (Fig. 112) in ripe proglottids is thrown into numerous, heavy, spermatozoa-laden coils which extend in a mass nearly to the middle of the proglottid. Within the cirrus-pouch the ductus ejaculatorius makes a few coils before passing over into the cirrus. The latter when protruded (Fig. 114), is short, thick and very muscular. Montieelli 's description agrees with this statement. The cirrus-pouch is short, broad and heavily muscled. Its length is about 0.23-0.25 mm. and its breadth about 0.10-0.15 mm. In maturing pro- glottids the ratio of its length to the segment breadth is 1 :5 or 1 :6 while in ripe proglottids it is about 1 :4. These organs (Figs. 112-115) are arranged as in the Ophio- taenia. The lumen of the vagina (Figs. 114, 190) near its opening to the exterior is large. The vagina is here surrounded by a strong sphinc- ter vaginae. There are no coils of vagina anterior to the ovary. A receptaculum seminis has not been seen. Montieelli (1899) states that it is present. The ovary is bilobed and it is situated in the posterior part of the proglottid. The lobes are thick, broad and short. Their outlines are more or less irregular. An oocapt, ootype, shell-gland, ovi- 257] PROTEOCEPHALIDAE—LA RUE 257 duct, unpaired vitelline duct, lower vagina, and a uterine passage are present and these organs are arranged in the manner common to the Proteocephalidae. Monticelli (1899) gives a long and detailed descrip- tion of the arrangement of these organs upon which no comments are necessary. Smith (1908) mistook these organs of the interovarial space for vitellaria. The vitellaria are lateral loosely follicular masses which extend throughout the length of the proglottid. The follicles are small, and in some preparations they took the stain poorly. It is probable that Smith had the same difficulty in staining the vitellaria and for that reason he entirely overlooked them. Monticelli states that the vitellaria lie outside of the inner longitudinal muscle layer. The writer has examined nothing but toto preparations which perhaps are not trust- worthy for the determination of this point. Nevertheless it seems that Monticelli 's statement is the result of a misinterpretation of the facts. The uterus (Figs. Ill, 113, 114, 115) is a median tube which in ripe proglottids (Fig. 112) has from 20 to 30 lateral outpocketings on either side. As these pouches fill with eggs they become rounded and the septa become indistinct. The uterus is not connected with the lobes of the ovary as Smith (1908) figures it. His figure is incorrect. The pouches are more numerous and more closely applied to each other and less slender than he shows them. Uterine pores were not visible in material examined by the writer. As to the method of discharging the eggs Monticelli (1899) writes: "Nelle ultime proglottidi I'utero, pregno a rimpinzato d'uova, sporge alquanto, facendo ernia contro le pareti, sulla faccia ventrale delle proglottidi. Non ho osservato orifizio esterno permante dell'utero, come quelle che Kramer ha visto in alcuni Tetraco- tylus (p. e. T. filicoUis) [Monticelli here cites PL 28 fig. 42 in Kramer's paper of 1892] e neppure ho constat© determinarsi uno sbocca prowi- sorio per dar uscita alle uova: penso, forse, I'uscita delle uova all 'esterno avvenga, come in altri casi, per deiscenza." According to Smith (1908) the six-hooked embryo measures 0.016- 0.018 mm. in diameter, the two membranes 0.028-0.030 mm. and 0.085- 0.100 mm. respectively. The writer was unable to measure or to study any eggs of this species hence he is not able to comment on Smith's data nor upon Monticelli 's description of the eggs which is here quoted : "Le uova uterine, relativemente piccole, hanno un guscio spesso e molto evidente : contengono gia I'oncosfera involta in una veste, od invoglio, che come una teca a netto contorno e non molte spessa, per quanto ben distinta, circonda, come in altri teniadi, I'embrione. Ciascun uovo, con il relativo guscio, e racchiuso in una capsula grande, sferoidale e di diametro assai pivi del doppio del guscio, 258 ILLINOIS BIOLOGICAL MONOGRAPHS [258 omologa analoga a quella che si osserva in altri cestodi (capsule uterine, od ovariche Auct.). La quale, come altrove ho dimostrato [Monticelli, Fr. Sav. — Sulla cosidetta subcuticola dei Cestodi, in : Rend R. Ace. So. Napoli, Fasc. 7-12, Luglio-Decembre 1892 (sul princpio dove parlo dell'uovo dei Cestodi e ne riassumo lo sviluppo).] nulla ha da vedere col guscio delle uova essendo essa una forma- zione molto diverso, secondaria e posteriore : circa I'origine di questa, oltre quanto ho espresso nel citato mio lavoro, veggasi pure il Diamare [Diamare, V. — II genere Dipylidium, in: Atti R. Accad. Sc. Nap. (2) Vol. VI. N. 7, 31 pp, 3 Tavole]. Capsula queste che ritengo possa e debba venir interpretata come una sorte di cocon e corrispondente a formazioni del genere che si osservano nelle uova di altri animali e ne circondona il guscio." Since Smith's specimens of Taenia eunectes Smith came from a host which is not uncommon in American zoological gardens and since his paper will probably be widely referred to by American investigators more specific attention is called to certain misinterpretations in the description and delineation of this species by Smith (1908) . His figure 4, PI. Ill which has not been reproduced shows very clearly that he con- sidered this form to be a species of Taenia. His attempt to make the organs of this species agree with those of Taenia has resulted in consid- erable confusion. The organ which he has labelled the vagina is the cirrus-pouch and vice-versa. The receptaculum seminis of his labelling is the mass of coils of the vas deferens. The lateral vitellaria he has omitted entirely. He labels vitellaria that mass of coils comprising the organs of the interovarial space. The ovary in this species is never connected with the uterus as he figures it, but always through the single oviduct, ootype, and uterine passage as has been figured (Figs. 99, 104). The writer has never seen* the lateral pouches of the uterus in this species or in any species of Ophiotaenia as Smith figures them. The uterus which he figures is characteristic of Taenia, not of a Proteoceph- alid. Unfortunately the writer has not been able to examine a proglot- tid from the material received from Smith that was in the same state of development as that shown in his figure. The writer has, however, examined younger proglottids and these in every case and in every essential particular agreed with the specimens received from other sources. There can be no doubt that Smith's specimens belong to the species Crepiddhothrium gerrardii Monticelli, hence the name Taenia eunectes is a synonym of C. gerrardii and should be suppressed. This is the only known species in the genus Crepidobothriura, It finds its nearest congeners among the larger species of Ophiotaenia. While in the structure of the proglottids and in the arrangement of the genital organs this species agrees almost perfectly with the Ophiotaenia 259] PROTEOCEPHALIDAE—LA RUE 259 there remain two characters which are deemed of sufficient value to warrant a separation of the snake Proteoeephalids into two genera. These characters are the structure of the suckers and the length of the neck. The first character has already been discussed. All the known species of Ophiotaenia have relatively long necks, i. e., 2-8 mm. long while C gerrardii has a short neck. Monticelli was amply justified in separating this species from his genus Tetracotylus, sensu latu. How- ever since it has been shown that his type species of Tetracotylus should be separated from the genus Proteocephalus and even from the family Proteocephalidae, his arguments in justification of his action are not repeated. Monticelli 's (1899) diagnosis of the genus Crepidobothrium reads: "Capo inerme, grande, rigonfio, piramidato : ventose ellittiche, posteriormente a margine interrotto e rientrante nel cavo della ventosa. Aperture genitali margi- nali, irregolarmente alternanti. Orifizio dell'antro genitale subventrale, largo : sbocco della vagina dorsalmente e disotto alia tasca del pene : ovario piccolo : testicoli piccolissimi, numerosi, coUocati nel mezzo della proglottide, internamente alia musculatura longitudinale interna, in unica serie. Utero allungato, tubolare, sacciforme. Vitellogeni piccoli, numerosi, periferici. Uova ravvolte in una capsula gelatinosa." His diagnosis does not require much amplification but may be re- stated thus. Crepidohothrium Monticelli: Head large, swollen, pyra- midal, tetragonal, unarmed. Fifth sucker vestigial. Suckers inversely cordate, posterior margin interrupted and re-entrant into sucker cavity. Genital aperture marginal, irregularly alternating. Vaginal opening dorsal to cirrus-pouch. Vagina anterior or posterior to cirrus-pouch. Testes in two lateral fields anterior to the ovary. Ovary bilobed, lobes irregular, relatively small. Uterus tubular, median, possessing in ripe proglottids numerous lateral outpocketings. All genital organs within inner longitudinal musculature except portion of cirrus-pouch and vagina. Eggs small, provided with three (?) membranes, outer one gelatinous. Type of genus: — Crepidohothrium gerrardii (Baird) from Boa con- strictor L. (type host) ; So. America (Bra2dl) (type locality). In the following table (pages 260-267) the principal data relating to the species of Ophiotaenia and Crepidobothrium are brought together : 260 ILLINOIS BIOLOGICAL MONOGRAPHS [260 ^^S. o > O 01 U (/2 ■5 S R E — • 3 MS s p E K U !; « E 111 ii 3« c u o n g > o o , , o H w S-5 E 3 E E2 o . J3 g E . c 00 o ^ o o c ^lg c ? Si X » <=> E ooo a 8-° 8e C4 E J" u " . o niS C u □• c E « „ to u *• o d E 0) X _ J3 o 'e ii 1 E _h. 3 £ C E « 00 . oE^ xBg beo o E-^ si: 3 o T-i ° Hi ©"rt "O o S o g •o t; c li . e« E "5 "3 E * c.S ^ P o 3„ "^'SS U So E U Ed ?! J.?9 cd -.2 X nl 5) " ^ C M ° " C . E o CQ . rt ** E £ .S gja ft^-oo E tco •a rt E . EE d=! E .A9 - tn 00 ?. > .2-- 4) O CM n o »- ?i « O" O 3 52 •5, - "3 Xoo oSd E e2 E- IS "O s M •< a e rt is B o U t« «.> ^ o _N VVM «>'.£ js' JS'S '?. M u u rt R'- 3 3 V o-rt O O I- -E- a Q.-0 ggE 01 S S2g t:.SE O U u 261] PROTEOCEPHALIDAE—LA RUE 261 o o 3 u u o V .2 ^•S *U 0) CO « p — ' — o C O « .2 o DO •; J; O .2 s'o I- c - S «• §"*'•£ a ^ o a J? «> E a-B V .2 a "O "5 O.B g e "« « c 5£ E 3 .•^ E u B9 u 60 S s o o 00 u U u u o o V H o E UM J o «J 0.0 ^ u tn •<- •*-» 4) 3 « IS o .^ Ji -5. ^o E 2" E V>w O . rt iJ _ . u -^ rt * O V CQ*^ *^ °E cg'S o ■< c a ( a p ja u |2 «» S E > D U (d 262 ILUNOIS BIOLOGICAL MONOGRAPHS [262 o. s t/3 ,c M-4 o c o tfl u u s,^ V 2 JS •« U o 1 o ^ •S. «> "oJ w c/) O U3 B o U ^ o E _c Em E d"! E 00 •°«^ d Mm : .d ■O ^ tl w V K S«j "O — n'O "3 Ji §§ o E .5 « K^ CJ^ E _c E fr s2 122 -TUB .5:1 cC^ t " S S "^ 2 °° i; S-S kg •s, .2 « ^"o N IS? cn o c a 3 8 „ E « 9" 9^ 2^5 go g O E V- ^ - U 263] PROTEOCEPHALIDAE—LA RUE 263 O V) in J £ u 5)nJ .t:^ ^ rt •-: ^> SB H'S. IS ^ « o en's *i3 .o-S C I. o •0 43 35 O^ 4) p 1-ss *3 ii B t"! 1- 00 d-2 * g — ~ 5 "C ."2 J2 n i= o. S o U I I i 3 V c E5 iJ"53 is « N 264 ILLINOIS BIOLOGICAL MONOGRAPHS [264 c •2 B2 • E 2e rt -co o « S u 3 O .^ '^ > E o « X c .c°E .M z a-^ ^ dtj^ E s u E E Globular, mm. in diam deep, 0.12-0. in diameter E so. 1^2 E <\ E cniiid T ■3 E •SE C V "3 o 1 ao4 e2 :^E 2 *• E j; E S «E E£ 2e Se "E E9 03 O O 2 5 >>H. O ^ Evo cJS E £ E.S ^ bo MS! a E o O S 2 i 3 E s -E« e9 c S « 3 V O u 2 o c t.SE 265] PROTEOCEPHALIDAE—LA RUE 265 o Ni5 a 5 C/J c «4-l o c o u U V ^-^ u CS ^ u s 5 3 ^ 2 o U So E E E r ^ o t? rt eo O « o ■n s »■ o as o o .2 f •^ P 3 JS u B I-, t; o 2.S tS o o c 4) a— ' <-5.S fO ^ •rt t • c.SE o a « g mE.S u -o*^ E E9 C Ol— c »-oo voo V _e 1> t- flj H o c « fc-2 <3 " >'5 ^3 s: c X bo 5 c "5 •as *> rt c ^>-5 J5 C '-^ «« 5; OS ^ p^ (9 " 00 J3 . "■-is «C5 5 <« » v- >'3 2 Co-*-* « n o •a tn C.Si o o («-0 ^o\ "» s (J S re .s 'i« 5 C u OU3 2| •d« -a X •a M •gSE 00 E g E E^ % ^ E . nt^-O g boot ji 00 o S. ^ s. •" wS! t, « o H e C E E c« o o j= ^ o « 60 • be ■5 , «? E^S •«■■ -Xl >• .5*38 E fc "O o Sfcog (i;-S.s.si 2.0 c (0 ao u (A O 2 o.^ bO*2 Jii »> « bo -o ESc '5i E E » E «* .§ "K'iE oIe a n c S Di P I; ^c'^E eS ^T* E Eo-tf=? l±^ (A n SO UOo ^1 8p E| .E 00 VO CM do « /-s O E o u •«• E a o OB V > E^c E-o «e2 SE-* bo id'/'E a §E 01^ Jj^E CXE «d •5 J .a £ li -E I. 8 o E t, o e S 2 ib. 2 o C t.S E 267] PROTEOCEPHALIDAE—LA RUE 267 8^ £ ■« J: to -I o o H c u j3 c« .Si ^ c/3 5 4) ~~^ U — (J o. B o T .•= o »■ CO C d ^ B * e -3 S .o o. o a 5 E »i 3 g e h" •- < 0"0 6 *=!£ CM O U fe'gE 3 O TO SE" 2Ee 15^ ooo ®d "dob d u H o 5 E odg I. « «° . 2 x.2„ <-3 O V dv ^CM o.Sd So:- H o So *> a Q H ^5 p2 c-a •a 2 u 2 « J3 . 3 „ c " u c a 5 a •«b -^ 3 « « •S-, "2 5 (t C o o .2 - S « ii- c 2 S «• o'o 2" . § >- C C« S<»4 tej S n •^ .5 ta.:.M c 111 a W ^s^ u a ««o> VC^ 0\ 2 §2 "3 ^ ,^*^ •oo 00 UIO.« o •sooa ct u mCg -s. t) ^ •B I •H 1 V ^^ Ooo II I V ^ 1-J3 V S-1 .2 B^ 5£ •e &i S> w w 268 ILLINOIS BIOLOGICAL MONOGRAPHS [268 OOCHORISTICA CRYPTOBOTHRIUM (von Linstow) La Rue 1906 : Ichthyotaenia crypt oh othrium von Linstow 1906 :185 1911 : Odchoristica crypt oh othria La Rue 1911 :481 ^ Under the name of Ichthyotaenia cryptohothrium von Linstow (1906) described a cestode from the intestine of a tree-snake, Chrysope- lea ornata Russell, Kurunegala. La Rue (1911) stated, but without assigning reasons therefor, that this species did not belong in the genus Ichthyotaenia or Proteocephalus but in the genus Ooehoristica Liihe. A careful examination of von Linstow 's description and figures shows that this species cannot belong to the Proteocephalidae. The position of the vitellaria in the Proteocephalidae as, indeed, in the whole order of the Tetraphyllidea is lateral, the vitellaria extending nearly the full length of the proglottid. In this species the vitellaria are globular masses lying just posterior to the ovary. This relation occurs in the Cyclophyllidea. Species of Odchoristica Liihe show this relation and since this genus includes other species of cestodes parasitic in snakes it seems probable that von Linstow 's species belongs here. La Rue (1911) therefore proposed for it the specific name Odchoristica crypto- hothria (von Linstow) La Rue. The specific name should end in "ium" not "ia" as he made it. Unless the invaginated or infolded condition of the head is a con- stant feature it can have neither generic nor specific importance. Ap- parently not enough is known concerning the heads of this species to establish the value of this condition as a diagnostic character. MONTICELLIA CORYPHICEPHALA (Monticelli) La Rue [Figs. 94-96, 132, 181, 186] 1891 1894 1896 1900 1911 Tetracotylus coryphicephala Monticelli 1891 :151-174 Ichthyotaenia coryphicephala Lonnberg 1894:803 Ichthyotaenia coryphicephala Riggenbach 1896:267 Ichthyotaenia coryphicephala Braun 1894-1900:1680-1681 Monticellia coryphicephala La Rue 1911:474 Specific Diagnosis: Characters of genus. Head dilated, somewhat triangular or globose, when seen from the front swollen, sub-quadrate, 269] PROTEOCEPHALIDAE—LA RUE 269 anteriorly elongated to form a conical elevation, unarmed and not very prominent, distinct from neck. Breadth of head perhaps 0.35 mm. Suckers four, fairly prominent, oval in shape, about 0.15 mm. long, situated at four angles of head. No fifth sucker. Neck very long, nar- row. First proglottids short, middle ones almost rectangular, posterior and last ones decidedly rectangular, swollen in the middle. Ripe pro- glottids about 1.80-2.0 mm. broad by 0.68-1.0 mm. long by about 0.34 mm. thick. Proglottids attached by full width. Intersegmental furrows shallow. Corners of proglottids not marked. Segmentation indistinct. Genital organs as in genus. Genital pore marginal, irregularly alternating in first one-fourth or one-fifth of proglottid length. No geni- tal papilla. Testes spheroidal, 0.05-0.085 mm. in maximum dimension, numerous, 100 or more, situated in single dorsal field outside of inner longitudinal muscle sheath. Vas deferens a mass of coils inside the inner muscle sheath. Cirrus-pouch 0.286-0.315 mm. long by 0.094-0.105 mm. broad. Length of cirrus-pouch 5 to 6 to 6^/^ times into proglottid breadth. Ductus ejaculatorius describing numerous coils. Cirrus slen- der, unarmed. Vagina and vaginal opening always anterior to cirrus- pouch. Vagina never crossing latter. Sphincter vaginae and receptacu- lum seminis present. Vagina within inner muscle sheath. Vitellaria lateral, . extensive, ventral, follicles forming a single layer in cortical parenchyma. Ovary posterior, bilobed, augmented by large protuber- ances, projecting dorsally, partially outside of inner muscle sheath. Organs of interovarial space as in Proteocephalidae. Uterus with many long slender lateral outpocketings, ventral, and outside of inner muscle- sheath. Egg-membranes not observed. Embryos 0.015-0.017 mm. in diameter. Habitat : Intestine of Silurus sp., locality not stated. Type : Slides in collection of Monticelli, from specimen No. 571 in the Zoological Museum at Vienna. This species was first described from Silurus sp. by Monticelli (1891:151-174). For this and nineteen other species of cestodes from fish he proposed the genus Tetracotylus, without, however, naming a type species. That genus was based on Taenia coryphicephala, the spe- cies which he described most completely. Lonnberg (1894:803) listed this as one of the species of Ichthyotaenia without entering into a dis- cussion of its anatomy. Riggenbach (1896:267) listed this among the species of Ichthyotaenia. Braun (1894-1900:1680-1681) states that Mon- ticelli 's genus Tetracotylus is based on the species Taenia coryphicephala but that the generic name suggested by Monticelli is a homonym of the name Tetracotyle suggested by Filippi (1854). He said moreover that 270 ILLINOIS BIOLOGICAL MONOGRAPHS [270 Tetracotylus had been used in place of Tetracotyle. For these reasons the name Ichthyotaenia should be used in place of it. La Rue (1911:474) established for this and certain other species the genus Monticellia and the family Monticellidae. This study is based upon data secured from Monticelli's (1891) paper and also upon Monticelli's type slides which Professor H. B. "\yard very kindly secured for study. This material originally came from the zoological museum at Vienna. The host of the species is Silu- rus sp. Monticelli (1891) is quoted on the external characters for the writer has examined only prepared slides of this species : "Capo slargato subtriangolare, visto di fronte, rigonfiato, subquadrato, ante- riormente allunganto a formare un cocuzzolo conico, inertne, non molto proeminente, ben distinto dal collo. Le quattro ventose mediocri non molto proeminenti, disposte ai quattro angoli del capo. Collo lunghissimo, ristretto. Prime proglottidi brevi, mediane subrettangolari, posteriori ed ultime decisamente rettangolari, rigonfie nel mezzo. Aperture genitali marginal! irregolarmente alternanti." Monticelli (1891) gives no dimensions of the head, neck and strobila. One of Monticelli's slides showed the head of Tetracotylus coryphi- cephala in toto. This head which had been badly compressed and somewhat broken by that treatment measured 0.459 mm. broad. This dimension, however, is too great and it seems that the normal head would not measure over 0.35 or perhaps 0.375 mm. The head should be described as somewhat globose rather than sub-triangular. The suckers could not be measured except in length which was about 0.150 mm. Monticelli's drawing of the' head (Fig. 132) shows that the suckers are irregularly oval in shape, the longitudinal axis of the suckers being the greater. The neck in this slide was too badly crushed to permit accurate measurement. It was cut off 3 or 4 mm. from the head and showed no traces of segmentation. No young proglottids were to be found in the slides examined by the writer. Four representative ripe proglottids were measured. Their dimensions were 1.95 mm. broad by 0.68 mm. long, 1.85 by 0.75 mm., 2.0 by 0.75 mm., 1.80 by 1.0 mm. Transections of ripe proglottids are about 0.34 mm, thick. The proglottids are at- tached by their full width. The angles of the segments can scarcely be seen and the intersegmental furrows are very shallow. These observa- tions were made on a limited amount of material so it is possible that some of the statements just made would require modification if consid- erable good material could be examined. The genital pore (Figs. 95, 186) is marginal, irregularly alternat- ing and situated at the end of the first one-fifth to one-fourth of the 271] PROTEOCEPHALIDAE—LA RUE 271 proglottid. There is no genital papilla. The genital pore (Fig. 181) leads into a small genital atrium into which both cirrus-pouch and vagina open. The vagina always lies anterior to the cirrus-pouch and its opening is also clearly anterior to the opening of the male ducts. Monticelli notes a sort of sphincter muscle about the genital atrium (Fig. 181). He states that this sphincter draws the opening of the vagina and cirrus-pouch very closely together. The testes are spheroidal. They measure from 0.05 by 0.05 to 0.05 by 0.06 to 0.07 by 0.085 mm., number about 100 or even more, and are situated (Fig. 95) dorsally in a field which covers the entire proglottid except that region occupied by the ovary and by a narrow strip on either lateral margin of the segment. There is no free median zone as Monti- celli states and as he shows in his figure, reproduced (Fig. 186). His statement that they are not numerous is incorrect. The testes (Fig, 94) are outside of the inner longitudinal muscle layer, a condition which does not occur in any species of the Proteocephalidae nor, so far as can be ascertained by the writer, in any family of Tetraphyllidea. A careful study of Braun's (1894-1900) great monograph on the cestodes gives no reason for believing that this condition has been observed heretofore in any order of cestodes. In the Pseudophyllidea he states definitely that the testes occur in the medullary layer. He makes the same statement for the Tetraphyllidea and the Cyclophyllidea. And as for the genital organs in the Diphyllidea and the Trypanorhyncha he states that they are as in the Tetraphyllidea. The location of the testes in this species then is unique. The vasa efferentia have not been observed. The vas deferens forms an elongated mass of coils which extends from the cirrus-pouch toward, but not reaching, the mid-field. This mass of coils lies just a little poste- rior to the cirrus-pouch and within the layer of inner longitudinal mus- cles. The duct of the vas deferens is not of uniform diameter through- out but is narrow in its beginning region then dilated and again con- stricted just before entering the cirrus-pouch. With its swollen coils the vas deferens functions as a vesicula seminalis. The cirrus-pouch (Fig. 181) is somewhat muscular, its muscles best developed near the outer end. Its length varies from 0.286 to 0.315 and even to 0.340 mm. and its breadth from 0.094 mm. in the longer pouches to 0.105 mm. in the shorter ones. The pouch tapers frequently to a blunt point at the inner end and is usually broadest near its opening. Its length goes 5 to 6 or 6^ times into the proglottid breadth. The ductus ejaculatorius (Fig. 181) is slender and has thin walls. It makes numerous intricate coils before passing over into the cirrus. The protruded cirrus has not 272 ILLIXOIS BIOLOGICAL MONOGRAPHS [272 been observed. As the cirrus appears in the cirrus-pouch it is weakly- muscular, not large, and is not armed. Probably when evaginated it would be long, slender, and without a thick base. As seen in a toto preparation the female organs appear to be ar- ranged in general as in the Proteocephalidae but a careful com- parison of this species wuth any Proteocephalid reveals striking differ- ences. The vagina (Fig. 95) always lies anterior to the cirrus-pouch and it never crosses the latter nor does it cross the mass of coils of vas deferens except in rare cases and then it crosses on the ventral side of only the most anterior coils, Monticelli states that it crosses the coils of vas deferens dorsally. The opening of the vagina is always clearly anterior to the opening of the cirrus-pouch. In a number of species of Proteocephalus and also of Ophiotaenia the opening is dorsal to the cirrus-pouch, and the writer is inclined to believe that if the remaining species of these genera were carefully investigated with that point in view many of these too would show the opening of the vagina dorsal to the cirrus-pouch. Near the vaginal opening is a weak sphincter vaginae. Beyond the sphincter the lumen of the vagina dilates slightly for a dis- tance, perhaps 0.3 mm., then it is constricted. After arriving in the mid-field of the proglottid the vagina again dilates considerably. This dilatation persists through several curves and coils until the vagina is just about to enter the interovarial space when the vagina is greatly constricted. The dilated region is the receptaculum seminis which is much more marked than in any species of Proteocephalus observed by the writer. As shown in transections (Fig. 94) the vagina, except its be- ginning portion, lies within the internal layer of longitudinal muscles. In this respect Monticellia coryphicephala agrees with the Proteocepha- lidae. The ovary (Fig. 95) is posterior and bilobed. A narrow, thin raid- piece connects the lobes which are long and broad. From the dorsal surface of the distal region of each lobe rounded prominences arise and extend toward the dorsal surface of the proglottid. Many of these prominences when observed in toto preparations seem to have no con- nection with the ovary and are readily mistaken for testes but when studied in transections they are seen to be a part of it. ]\Ionticelli 's drawing which is reproduced (Fig. 186) does not truly represent this appearance. These dorsal prominences and the greater part of the ovarian lobes (Fig. 96) from which they arise lie in the cortical paren- chyma outside of the internal layer of longitudinal muscles. The mid- piece and part of the lobes of the ovary lie within the muscular sheath. Monticelli (1891) failed to point out this condition. Here is a relation. 273] PROTEOCEPHALIDAE—LA RUE 273 the like of which the writer has been unable to find elsewhere in all the cestodes. So far as he is able to determine the ovary of other cestodes always lies in the medullary parenchyma. At the posterior margin of the ovarian mid-piece is situated the oocapt. This organ was called the "sfintere ovarico" by Monticelli. The oocapt leads into the oviduct which after making several coils re- ceives the vagina. Then as a fertilization passage the oviduct continues until it reaches the ootype which is surrounded by the shell glands. Just before entering the ootype the oviduct receives the unpaired vitel- line duct. The ootype discharges into the uterine passage which passes ventral to the ovary and then discharges into the uterus. It will be seen from a comparison of the above description with drawings and descrip- tions of similar organs in the Proteocephalidae that there is marked agreement between Monticellia and the Proteocephalidae in these rela- tions. However this is no more than can be reasonably expected when it is remembered that practically the same plan for these organs is fol- lowed throughout the whole order of Tetraphyllidea to which Monticel- lia and Proteocephalus belong. Monticelli (1891) takes occasion to point out what seems to be misinterpretations on the part of von Lin- stow (1891) in describing these organs in Taenia longicollis. The writer agrees with Monticelli in considering that von Linstow has mistaken the oocapt for the ootype. A farther discussion of this point will be found in the description of Proteocephalus longicollis. The vitellaria, which in the Proteocephalidae are lateral, follicular masses, the individual follicles of which are closely grouped about a central conducting tubule, are in Monticellia coryphicephala (Fig. 95) widely scattered lateral follicular masses which lie in a single ventral layer. In Proteocephalids the vitellaria are within the inner longitudi- nal muscle layer while in M. coryphicephala they lie outside of those muscles. The vitellaria are not only ventral but at the margin of the proglottid they turn up toward the dorsal surface, hence when viewed in a toto preparation the vitellaria at the margins seem greatly com- pacted. Transections (Fig. 94) of the proglottids show the method of arrangement of the vitellaria. The lateral longitudinal vitelline ducts have not been seen on account of the poor histological condition of the material. The paired vitelline ducts however, may be seen to arise in the lateral fields and to pass toward the middle of the proglottid outside of the longitudinal muscle layer. After running for some distance in this relation the ducts turn dorsally and enter within the muscle layer and then they pass on to the middle of the proglottid where the paired vitelline ducts unite to form the unpaired vitelline duct which discharges into the ootype. In all the known species of Proteocephalidae the vitel- 274 ILLINOIS BIOLOGICAL MONOGRAPHS [274 line ducts are always within the longitudinal muscle layer. Monticelli failed to note the position of the vitelline ducts in M. coryphicephala. The uterus (Fig. 95) in ripe proglottids is made up of about 18-30 slender out-pocketings, which extend well toward the margins of the proglottids but not as far laterad as in certain species of Proteocephalus such as P. fallax, P. duhius, and P. ambloplitis. Monticelli (1891) states that the uterus when filled with eggs causes the ventral surface of the proglottid to belly out. Unfortunately his drawing showing that con- dition has not been reproduced. The uterus (Fig. 94) is ventral and it too lies outside of the internal layer of longitudinal muscles. Uterine pores have not been observed. Monticelli says that they do not exist but that when the uterus is full the ventral body wall ruptures, thus discharging the eggs. A careful study of good material would probably show the presence of one or more uterine pores such as was found by Kramer (1892), Schneider (1905) and by the writer in a large number of Proteocephalids. Monticelli gives no measurements of the uterine eggs. He states that the membranes are quite delicate and that the uterine eggs are very small. In one of Monticelli 's slides a broken pro- glottid rendered some of the eggs visible. The spheroidal embryos measured about 0.015 to 0.017 mm. in diameter. The membranes had become so transparent that they could not be measured. In the above description and in the drawings mentioned it has been shown that Monticellia coryphicephala differs from the Proteocephalidae and especially from the typical species of Proteocephalus in a number of characters which concern the position of the genital organs and their relation to the inner longitudinal muscle layer. In all the Proteocepha- lids which have been sufficiently investigated to determine these points the entire genital apparatus with the exception of a portion of the cirrus-pouch and vagina lies within the inner longitudinal muscle layer. Moreover, the follicles of the vitellaria are closely packed about a central duct. In Monticellia the vitellaria are in two broad lateral fields the follicles of which are scattered in a broad single layer. The paired vitelline ducts for a considerable distance lie outside the inner muscle layer. The testes and uterus are entirely outside this muscle layer and the ovary is partly outside of it. As in the Proteocephalidae the vagina, vas deferens and part of the cirrus-pouch are within the inner muscle layer. On account of these marked differences between the Proteo- cephalidae and the form which Monticelli named Tetracotylus coryphi- cephala the writer (1911:474) has seen fit to establish a new genus Monticellia in honor of Professor Monticelli. The status of Monticelli 's generic name Tetracotylus has already been reviewed in the introductory section where the new genus has been 275] PROTEOCEPHALIDAE—LA RUE 275 defined as has also the new family Montieellidae. In this genus and family probably belong Tetracotylus diesingii Monticelli, T. macrocoty- lea Monticelli and Taenia malopteruri Fritsch. These three species are all parasitic in the Siluridae. Perhaps Taenia osculata Goeze belongs here also. It seems preferable, however, for the present to consider this last as a species inquirenda in the genus Proteocephalus in which it has long been considered to belong. More careful study into the morphology of Taenia osculata is desirable in order that its systematic position may be determined. MONTICELLIA MACROCOTYLEA (Monticelli) [Fig. 125] Tetracotylus macrocotylea Monticelli 1891 1891 1896 1911 Ichthyotaenia macrocotylea Riggenbach 1896:267 Monticellia macrocotylea La Rue 1911 :474 This species was described by Monticelli (1891). Lack of sufficient good material prevented a careful study of it. Riggenbach (1896:267) listed this form in the genus Ichthyotaenia. La Rue (1911:474) in- cluded this species in the genus Monticellia. Monticelli 's original de- scription is here quoted: ''TAENIA MACROCOTYLEA.— Questa Taenia, che indico cosi dalle sue proeminenti ventose, ha raolte rassomigli- anze con le due seguenti, ma da entrambe si distingue per la caratteris- tica forma del capo che e nettamente distinto dal collo e per il eoUo piu breve. Le aperture genitali sono marginali irregolarmente alternanti. Lo stato deir individuo che posseggo non mi ha permesso uno studio piu minuzioso di questa Taenia. • • • * * Habitat: intestino del SUurus megacephalus." Professor H. B. Ward very kindly secured Monticelli 's type slides of this species for examination. As a result of this examination the writer is able to add the following data to the original description. The head of this specimen is slightly crushed. In this condition it measures 1.10 mm. broad, a figure which is probably too large by 0.10- 0.20 mm. Its length is about 0.90 mm. The suckers are prominent and heavily muscled. They measure 0.45 to 0.50 mm. in diameter. The sucker cavity could not be measured. The neck is about 0.50 mm. broad just back of the head. Its length could not be ascertained for it was broken off. Mature proglottids measure about 0.75 mm. square. No young or ripe proglottids could be seen. The segmentation is distinct. The genital pore is marginal, irregularly alternating, and situated in the first one-fourth of the proglottid. It is rendered prominent by a 276 ILLINOIS BIOLOGICAL MONOGRAPHS [276 small genital papilla. The length of the cirrus-pouch and the relations of the latter with the vagina could not be ascertained. The testes num- ber about 100 or more, and they are situated in a single field between the vitellaria. The vitellaria are lateral follicular organs, the follicles of which are scattered much as they are in Monticellia coryphicephala. The ovary is bilobed, and it occupies a posterior position on the pro- glottid. The material, however, is too poor to permit of a careful study of this organ. The uterus could not be seen. This species belongs in the genus Monticellia La Rue. It is differ- entiated from the other species of the genus by reason of its larger head and suckers, its prominent genital pore and its evident segmentation. Unfortunately the material is so poor that a careful study is not per- mitted and as a consequence its exact relation to the other species of the genus cannot be determined. MONTICELLIA DIESINGII (Monticelli) [Fig. 157] 1891 1896 1911 Tetracotylus diesingii Monticelli 1891 Ichthyotaenia diesingii Riggenbach 1896:267 Monticellia diesingii La Rue 1911:474 This species was very inadequately described by Monticelli (1891) whose material was too limited and too poor to permit a careful stul!y. Riggenbach (1896:267) listed it as one of the species of Ichthyotaenia but gave no description of it. La Rue (1911:474) included this form among the species of Monticellia. Monticelli 's original description is here quoted: "TAENIA DIESINGII.— Capo subgloboso anterior- mente rotendato appena distinto dal coUo. Le quattro ventose grandi, proeminente e molto muscolari. CoUo assai lungo: prime proglottidi brevissime appiattite, proglottidi mediane alquanto rigonfie all' aspetto cerciniformi, posteriori rettangolari, ultime subquadrate. Aperture gen- itali irregolarmente alternanti. L'apparato genitale, da quanto mi e riuscito vedere, si assomiglia a quello della T. coryphicephala. Habitat: intestino del SUurus dargado." Thanks to Professor H. B. Ward the writer has been able to exam- ine Monticelli 's type slides of this species and can add the following data to the original description. The head is about 0.30 mm. in breadth. Suckers measure about 0.17 mm. in their maximum dimension while the opening of the same is about 0.08 mm. long. The musculature of the sucker is thick. Altho 277] PROTEOCEPHALIDAE—LA RUE 277 the neck of this specimen is broken into several pieces, its pieces total about 3-5 mm. in length. The young proglottids are about 0.05 mm. long by 0.34 mm. broad. Fully mature proglottids are about 0.80 mm. broad by 0.45-0.50 mm. long. Since the proglottids are attached by their full width the segmentation is not distinct. The genital pore is marginal, situated within the first one-third or one-fourth of the proglottid. Its position alternates irregularly. The cirrus-pouch is about 0.265 mm. long by 0.105 mm. broad. The ductus ejaculatorius forms numerous coils within the cirrus-pouch. The cirrus is slender and not strongly muscular. It was not seen protruded. Testes numbering about 100 are situated in the whole dorsal field between the vitellaria. The coils of vas deferens could not be seen. The vitellaria are lateral and the follicles seem to be scattered much as in Monticellia coryphicephala. It was not difficult to determine that the bilobed ovary is situated in the posterior part of the proglottid but it was impossible to determine its true character. The vagina lies anterior or posterior (?) to the cirrus-pouch. Uterus and eggs could not be observed in this material. It is unfortunate that it is impossible to give a more complete description than is here given. The specimens were stained with car- mine which at its best, does not yield good outlines of organs in the cestodes. In this case the differentiation was poor making a careful study out of the question. Altho much to be desired it did not seem advisable on account of the extremely fragile condition of the specimens to attempt a restaining of the material, even had Professor Monticelli been willing that the attempt be made. The study of this material has convinced the writer that this species belongs to the genus Monticellia La Rue. It is closely related to M. cory- phicephala but seems to be quite distinct from that species. Without an examination of more material many points must remain in doubt. MONTICELLIA MALOPTERURI (Fritsch) La Rue [Figs. 154, 166] 1886: Taenia malopteruri Fritsch 1886:103-108 1891 : Taenia malopteruri Monticelli 1891 1896: Ichthyotaenia malopteruri Riggenbach 1896:267 1911 : Monticellia malopteruri La Rue 1911 :474 Specific Diagnosis: Characters of genus. Length unknown. Breadth as much as 1.5 mm. Scolex fairly large, 0.45 mm. in breadth, quadrangular, bearing four prominent suckers. Rostellum ( ?) hemi- 27S ILLINOIS BIOLOGICAL MONOGRAPHS [278 spherical, armed with many small hooks. Suckers large, heavily muscled, protuberant, 0.25 mm. in diameter. Neck short, nearly broad as head. Mature proglottids nearly quadrate. Ripe proglottids broader than long, 1.46 mm. broad by 1.1 mm. long. Genital organs as in genus. Genital pore marginal, irregularly alternating, near middle of pro- glottid. Pore large, marked by a thickening of margin. Cirrus, when protruded, short and filiform. Cirrus-pouch short and relatively small, extending about one-fifth across proglottid breadth. No coils of ductus ejaculatorius in pouch. Vas deferens, a mass of coils extending to mid- dle of proglottid. Testes filling up field between vitellaria, about 120 in number. Vagina posterior to cirrus-pouch. No coils of vagina anterior to ovary. Ovary a bilobed, winglike structure. Vitellaria follicular, situated in lateral fields. Uterus, a median tube with 18-20 lateral pouches. Eggs, not described. Habitat: In the intestine of Malopterurus electricus ( ?), Egypt. Fritsch described and figured this form in 1886 as Taenia malop- teruri. Monticelli (1891) included this species in his group of fish cestodes. He did not describe it. Riggenbach (1896) considered this a species of Ichthyotaenia. La Rue (1911:474) considered this to be a species of Monticellia. Fritsch 's diagnosis reads: ^'Taenia malopteruri, Caput quadrangu- lare, acetabulis quattuor, angulariter positis robustis. Rostellum hemis- phaericum, spinis obtusis vel tuberculis minimus ornatum. Collum mediocre. Aperturae genitalium marginales leviter circumvallatae. Corpus sulco profundo per medium impressum. Articuli adulti dimido fere longiores quam lati, proglottides breves, contracti. Habitat in intestino Malopteruri." The description given by Fritsch is very in- complete. However, he figures the head and a nearly ripe proglottid, stating the magnification of the same. Since this is true one can secure some size relations by measuring the organs portrayed in the drawings. In doing this care must be used because in some respects the drawings are not altogether clear, nor can one always determine the character of certain organs. Nevertheless the writer has used these measurements in the full realization that they were inaccurate but believing that they probably are correct within the limits of variation of the species. Besides the study of these drawings the description is based upon Fritsch 's (1886) description. The length is not stated. In breadth the worm may measure as much as 1.5 mm. The scolex (Fig. 154) is of fair size, 0.45 mm. in diameter. It is quadrangular and bears four prominent suckers and an hemispherical rostellum (?), armed with many small hooks. Suckers 279] PROTEOCEPHALIDAE—LA RUE 279 are large, 0.25 mm. in diameter, heavily muscled, and protuberant from the angles of the head. The neck is short but nearly as broad as the head. Fritsch failed to state the proportions of the young proglottids, nor are the latter figured. Mature proglottids are nearly quadrate while ripe ones are somewhat broader than long. Ripe proglottids measure about 1.46 mm. broad by 1.1 mm. long. The genital organs are arranged according to the type of the genus. The marginal genital pore alter- nates from side to side. It is situated near the middle of the proglottid, is of large size and is marked by a considerable thickening of the mar- gin. The cirrus is sometimes protruded and is then short and slender. The cirrus-pouch is relatively small and short. Its length goes into the proglottid breadth about five times. The ductus ejaculatorius forms no coils within the cirrus-pouch. The coils of the vas deferens form a knot extending from the cirrus-pouch to the middle of the proglottid. Testes are irregularly scattered between the vitellaria and the ovary. Fritsch figures about 120 of them. His drawing which is reproduced here (Fig. 166) does not show them in the mid-field. This may be explained in three ways: first, that the testes occupy only the lateral fields of the proglottid, second, that the preparation was of such a nature that the testes if present could not be seen on account of the eggs in the uterus, or third, that they were poorly stained. Without having seen the specimens on which Fritsch 's description is based or specimens known to belong to the same lot or from the same host species one is unable to judge on this point. It is well, perhaps, to call attention to the fact that testes in ripe proglottids do not take the stain well nor are they easily seen through the mass of eggs in the uterus. The vagina opens posterior to the cirrus-pouch. "Whether it ever opens anterior to the pouch is not stated. There are no coils of the vagina anterior to the ovary. The ovary is bilobed, each lobe being somewhat winglike. It is in the posterior part of the proglottid. The lobes are apparently follicular at the outer ends, tho this feature could not be determined with any accuracy unless an examination of Fritsch 's specimens were made. The vitellaria are long follicular masses in either lateral field. From the drawing the follicles of the vitellaria seem to be compacted rather than widely scattered as in the type of the genus. The uterus is a median tube from which, apparently, many lateral pouches arise. In the drawing by Fritsch these pouches are rather indistinct, but about 18-20 on either side can be seen with some degree of certainty. In the drawing, reproduced (Fig. 166) these structures are made more distinct than in the original. The eggs were not de- scribed by Fritsch. % 280 ILLINOIS BIOLOGICAL MONOGRAPHS [280 The systematic position of this species is not readily determined from the data at hand. Fritsch's description leaves much to be desired and his figures are not sufficiently definite to render possible a positive determination. Nevertheless, certain features of the anatomy of the worm are so well delineated that some definite conclusions can be reached. The rounded summit of the head covered wath numerous spines and the very prominent suckers which seem to be set on the surface of the head are not typical of Proteocephalus. Species of that genus lack spines on the head and their suckers are never as prominent as in the species under consideration. The head agrees very well with that of Moniicellia coryphicephala Monticelli in regard to the suckers. The latter species has no spines. In the genital organs there seems, in the main, to be a good agreement with the members of the genus Pro- teocephalus. Nevertheless, a careful examination and comparison of Fritsch's figure of the proglottid (Fig. 166) with the writer's figure of Monticellia coryphicephala (Fig, 95) shows a certain resemblance that cannot be overlooked. In both species there is the more or less indefi- nitely outlined ovary made up of follicles at the outer regions. These follicles seem to be smaller in this species than in M. coryphicephala. The vitellaria, apparently, are not as extensive in the former as in the latter, yet they are different from those in Proteocephalus. The lips of the genital sinus are much more prominent in this species than in Proteocephalus. This character was not mentioned by Monticelli as being present in Tetracotylus nor has the writer noted it in his specimens. In view of the facts above presented the writer must conclude that the species does not belong to the genus Proteocephalus Weinland. With some reservation this species is assigned to the genus Monticellia La Rue. The species is then to be knoAvn as Monticellia malopteruri (Fritsch) La Rue. The species of cestodes infesting the Siluridae merit much more careful study by modern methods. As yet their structure and relationships are almost unknown. The literature contains but few references to cestodes of this group. The writer has noted the descrip- tions of the species Tetracampos ciliotheca Wedl and Marsypocephalus rectangulus Wedl reported by Wedl (1861) from Heterobranchus an- guUlaris. The former because of its ventral genital pore, ciliated embryo and two bothria evidently belongs to the order Pseudophyllidea. The latter species may belong somewhere in the Proteocephalidae or Monti- cellidae but not sufficient data are given to warrant a positive determi- nation. Wedl (1861) also reported Scolex syndontis from Syndontis schal and from Heterobranchus anguUlaris. These specimens, likewise, cannot be definitely placed. 281] PROTEOCEPHALIDAE—LA RUE 281 DISTRIBUTION OF PROTEOCEPHALIDAE The data upon which this section is based are meager yet it has seemed desirable to work over the available records to find out if there be any principles governing the distribution of the group, to find out the relation of the parasite to the primary hosts and perhaps to the secondary hosts. This section falls naturally into two parts: A, con- cerning the Proteocephalids infesting the amphibians and reptiles, and B, concerning those species which infest fish. The data under the first heading are grouped into certain tables and a discussion of the contents of the tables. The data bearing on the second heading, i. e., on the fish Proteocephalids are grouped under the following rubrics: List of ces- tode species with hosts and locality of finding; Distribution according to continents; Host species harboring two or more Proteocephalid spe- cies, with the distribution of the latter; Proteocephalids found in more than one host species, a discussion of each case including notes on the distribution and food habits of the hosts; Families of fish from which Proeocephalids are known and the species of the latter. Distribution op Proteocephalids of Amphibia and Reptilia Amphibian Proteocephalids are known from but two continents, North America and Australia. These species are Ophiotaenia filaroides and 0. lonnhergii for North America and 0. hylae for Australia. The North American species are from the Caudata while the Australian species is from one of the Salientia. Reptilian Proteocephalids are known from all the continents. In North America are found Ophiotae- nia marenzelleri, 0. grandis, 0. perspicua, and 0. lactea sp. inq. In South America are found 0. calmettei, 0. racemosa, and Crepidoboth- rium gerrardii. In Europe a single species is known, namely 0. nat- tereri. Africa, likewise, has yielded but a single species, 0. punica. Asia including the tropical islands usually included in the Oriental region has three species, Acanthotaenia shipleyi, Ophiotaenia pigmen- tata, and 0. trimeresuri. In Australia, i. e., in the Australian region which includes new Guinea, there are no species of Ophiotaenia from reptiles but there are four species of Acanthotaenia from reptiles, viz. A biroi, A. saccifera, A. tidswelU, and A. gallardi. To sum up this data there are species of Ophiotaenia from each continent, species of Acanthotaenia from two continents, Asia and Aus- tralia, and one species of Crepidobothrium from South America. As 282 ILLINOIS BIOLOGICAL MONOGRAPHS [282 yet none of these species are known to occur in more than one conti- nent. The distribution of each species seems narrow. There are, how- ever, but few records and the data are incomplete. When more records are available it may be found that some of these species may have a far wider distribution. In all the cases known the hosts are aquatic or semiaquatic animals and they feed in part at least upon animals which like themselves are aquatic or semiaquatic in their habits. It has not been possible to work over the rather scant literature on the food habits of these animals hence no data on that topic are here presented. It is to be hoped that someone may make a study of the food of these hosts and thus enable to be made a determination of the relationships of these parasites to each other and to their hosts. An accompanying table gives the names of the parasites, their hosts and the locality of the collection. In another table the parasites have been grouped according to the order and family of the host. The latter table shows that there are Proteocephalid species from Caudate and Salientian Amphibians, from the Varanidae, a family of Lacertilian Reptiles, and from three families of Serpentes (Ophidia). These fami- lies are Boidae, Colubridae, and Viperidae. A single subfamily in each of the Boidae and Viperidae furnish hosts for Proteocephalids while in the family Colubridae one subfamily belonging to each of the three se- ries furnishes host species. At the bottom of the table is placed a species which tho reported to have been taken from a dog is certainly not a dog cestode. Its nearest relatives, anatomically, are the Proteocephalids of snakes and particularly the Proteocephalids of the Crotalinae. It has been suggested elsewhere that the real host was probably one of the Crotalinae. Because of the small amount of data it has not seemed justifiable to draw many general conclusions in regard to these para- sites. 283] PROTEOCEPHALIDAE—LA RUE 283 Hosts and Localities Reported for Proteocephalids of Amphibia and Reptilia Cestode species Hosts Locality Acanthotaenia biroi (von Varanus sp. New Guinea Ratz) A. gallardi Johnston Pseudechis porphyriacus Shaw New South Wales P. australis Gray New South Wales Notechis scutatus Peters New South Wales Denisonia superba Gunther New South Wales A. saccifera (von Ratz) Varanus sp. New Guinea A. shipleyi von Linstow Varanus (Hydrosaurus) salvator Ceylon A. tidswelli Johnston Varanus varius Shaw New South Wales V. gouldii Gray Burnett River, Australia V. bellii (a variety of V. Burnett River, Australia varius) Crepidobothrium gerrardii Eunectes murinus Wagl. South America (Baird) Boa constrictor L. South America Ophiotaenia calmetti (Bar- Lachesis (Bothrops) lan- Martinique, West Indies rois) ce olatus L. Sao Paulo, Brazil 0. filaroides La Rue Amblystoma tigrinum (Green) Nebraska and Kansas 0. grandis La Rue Ancistrodon piscivorus Holbr. Southern United States 0. hylae Johnston Hyla aurea New South Wales 0. lactea (Leidy) sp. inq. Matrix sipedon (?) Eastern United States 0. lonnbergii (Fuhrmann) Necturus maculosus Ohio and Indiana 0. marenselleri (Barrois) Ancistrodon piscivorus Holbr. ( ?) Southern United States O. nattereri (Parona) Coluber sp. Liguria, an Italian province O. perspictia La Rue Natrix rhombifer Hallo- well Illinois and Oklahoma 0. piginentata (von Lin- P sa mm dynast es pulver- Java (Semarang) stow) ulentus Boie 0. punica (Cholodkovski) Dog (?), probably a snake Island of Dscherba, Tunis C. racemosa (Rudolphi) Coluber sp., Ophiomorphus Brazil miliaris, Ophis merremii Brazil 0. trimeresurus (Parona) Trimeresurus formosus Island of Mentawei, East Indies 284 ILLINOIS BIOLOGICAL MONOGRAPHS [284 Families of Amphibia and Reptilia Harboring Proteocephalid Parasites Order Family Proteidae Necturtis maculosus Raf. Family Amblystomidae Amhlystoma tigrinum (Green) Order Family Hylidae Hyla aurea Order Suborder Family Varanidae Varanus (Hydrosaurus) salvator Varanus varius Shaw Varanus gouldii Gray Varanus bellii Varanus sp. Varanus sp. AMPHIBIA Caudata (Urodela) Ophiotaenia lonnbergii (Fuhrmann) Ophioiaenia filar oides La Rue Salientia (Anura) Ophiotaenia hylae Johnston REPTILIA Squamata (Sauria) Sauria (Lacertilia) Acanthotaenia shipleyi v. Linstow Acanthotaenia tidswelli Johnston Acanthotaenia tidswelli Johnston Acanthotaenia tidswelli Johnston Acanthotaenia biroi (von Ratz) Acanthotaenia saccifera (von Ratz) Suborder Serpentes (Ophidia) Family Boidae Subfamily Boinae Eunectes murinus Wagl. Boa constrictor Family Colubridae Series A. Aglj'pha Subfamily Colubrinae Natrix rhombifer Hallowell Natrix sipedon Coluber sp. Coluber sp. Ophiomorphus miliaris Ophis merremii Series B. Opisthoglypha Subfamily Homalapsinae Psammodynastes pulverulentus Boie Series C. Proteroglypha Subfamily Elapinae Pseudechis porphyriacus Shaw Pseudechis australis Gray Notechis scutatus Peters Denisonia superba Gtmther Crepidobothrium gerrardii (Baird) Crepidobothrium gerrardii (Baird) Ophiotaenia perspicua La Rue Ophiotaenia lactea (Leidy) sp. inq. Ophiotaenia nattereri (Parona) \/^ Ophiotaenia racemosa (Rudolphi) Ophiotaenia racemosa (Rudolphi) Ophiotaenia racemosa (Rudolphi) Ophiotaenia pigmentata (von Linstow) Acanthotaenia gallardi Johnston Acanthotaenia gallardi Johnston Acanthotaenia gallardi Johnston Acanthotaenia gallardi Johnston 285] PROTEOCEPHALIDAE—LA RUE 285 REPTILIA Suborder Serpentes (Ophidia) Family Viperidae Subfamily Crotalinae Triineresurus forinosus Ophiotaenia trimeresuri (Parona) Lachesis (Bothrops) lanceolatush. Ophiotaenia calmettei (Barrois) Ancistrodon piscivorus Holbr. Ophiotaenia marenselleri (Barrois) Ancistrodon piscivorus Holbr. Ophiotaenia grandis La Rue Host uijknown, reported to have come from a dog but probably from a snake Ophiotaenia punica (Cholodkovski) PROTEOCEPHALIDS OF FISH Hosts and Localities of Collection of Proteocephalid Species infesting Fish and the Species of Pish infested Cestode Species Hosts Locality Proteocephalus a- Alosa finta var. lucustris Lake Como, Italy gonis P. ambloplitis Ambloplites rupestris Lake George, New York Micro pterus salmoides Lake George, New York; Walnut Lake, Mich. ; Pelican Lake, Minn. Micropterus dolomieu Lake St. Clair, Mich.; Lake Men- dota, Wis. Aiiiia calva Lake St. Clair, Mich. ; Lake Erie P. cernuae Acerina cernua Konigsberg, Prussia; Lake Bala- ton, Hungary (?)A'cerina schraetser Lake Balaton, Hungary P. Cyclops sp. inq. Coregonus maraena Schallsee, Germany P. dubius Perca fluviatilis Lake Geneva, Switzerland P. esocis Esox lucius Reval, Esthonia (a Baltic prov- ince) P. exiguus Coregonus nigripinnis, C. Lake Michigan, near Charlevoix, prognathus, C. artedi Mich. P. fallax Coregonus maraena=(fera) Lake Lucerne, Switzerland P. filicollis Gasterosteus aculeatus Greifswald ; Berlin ; Paris ; Ire- land G. pungitius Rennes ; Halle ; Greifswald ; Re- val, Esthonia; Porkhala, Fin- land; Upsala, Sweden. P. fossatus Pimelodus pati Rio Paraguay, S. A. P. hemisphericus Anguilla vulgaris Padua, Italy sp. inq. P. longicollis Coregonus wartmanni / ? C. wartmanni nobilis Lake Lucerne 286 ILLINOIS BIOLOGICAL MONOGRAPHS [286 Cestode Species Hosts Locality P. longicollis C. maraena=(C. lavaretus Greifswald; Rositten, E. Prussia; and C. fera) Lake Geneva C. maraenula Berlin C. albula Nikolaiken, E. Prussia C. schinzii helveticus Lake Lucerne C. exiguus albellus Lake Lucerne • Osmervs eperlanus Berlin; locality not recorded sev- eral times Trutta trutta Germany ( ?) T. fario ? Saint thymallus ? S. salveHnus=S. alpinus and Lake Lucerne ; Lake Geneva ; lo- S. umbla cality not stated Very doubtful hosts!!!! (?) Esox Indus Lake Lucerne; Lake Balaton, Hungary {?)Perca fluviatilis Lake Lucerne (?) Albumus lucidus Lake Lucerne _. (?) Squalius cephalus Lake Lucerne (?)Leuciscus leuciscus Lake Lucerne P. macrocephalus Anguilla vulgaris Greifswald ; Memel, East Prussia ; Rennes ; Padua ; Narenta ; Trieste; Lake Lucerne; Finland Anguilla chrysypa Wood's Hole, Mass. ; Sebago Lake, Maine P. macrophallus Cichla monoculus Spix Brazil sp. inq. P. neglectus "Forelle", Trutta fario Lake Lucerne and Lake Geneva, probably P. nematosoma sp. Esox reticulatus Locality not known, probably inq. eastern United States P. osculatus sp. Silurus giants Magdeburg and Greifswald inq. P. pentastoma Polypterus bichir Khor Attar on White Nile P. percae Perca norvegica ? Perca fluviatilis Greifswald; Rositten, East Prus- sia ; Finland ; Upsala Coregonus viaraena={C. Finland lavaretus) {})Acerina cernua ? ( ?)Cottus quadricomis Finland (?)Gasterosteus aculeatus Rositten, East Prussia P. perplexus Aitiia calva and Lepisosteus platostomus Illinois River, Havana, Illinois 287] PROTEOCEPHAUDAE—LA RUE 287 Cestode Species Hosts Locality P. pinguis Esox reticulatus Sebago Lake, Maine Esox lucius Walnut Lake, Michigan Lake Geneva, Wisconsin P. pusillus Saint sebago Sebago Lake, Maine Cristivomer namaycush Lake Temagami, Ontario Proteocephalus sa- Cobitis barbatula Petersburg and Province of Nov- gittus sp. inq. gorod, Russia P. salmonis-umblae Salmo salveUnus=^{S. um- Lake Geneva, Switzerland, Ger- sp. inq. bla) many P. salvelini sp. inq. Cristivomer namaycush Outer Island, Lake Superior P. singularis Lepisosteus platostomus Illinois River, Havana, 111. P. skorikowi Acipenser stellatus River Gurgen, Caspian Sea P. sulcatus Polypterus endlicheri Duem on the White Nile Clarotes laticeps Khartoum on the White Nile P. torulosus Idus melanotus={Cyprinus jeses and Leuciscus idus) Berlin; Greifswald; Finland Leuciscus leuciscus= Germany ( ?) ; Podiebrad, Bo- (Squalius leuciscus) hemia ; Lake Lucerne L. grislagine Locality (?) Alburnus bipnnctatus ? (Material in M. C. V.) A. sp. Germany (?) (from context of report) A. lucidus Lakes Geneva and Lucerne Germany (?) (from context of report) Aspius rapax Germany (?) (from context of report) Abramis brama Lake Balaton, Hungary Pelecus cultratus Lake Balaton, Hungary Gobio fluviatilis Lake Lucerne Blicca bjoerkna Lake Lucerne Very doubtful hosts ! ! ! ! ! {DCoregonus maraena Lake Lucerne (fera) (?)C exiguus albellus Lake Lucerne (?)C. schinsii helveticus Lake Lucerne (?) Salmo salvelinus Lake Lucerne (?)Perca fluviatilis Lake Lucerne and Podiebrad, Bo- hemia (?)Lota vulgaris Lake Geneva Corallobothriuvt Malopterurus electricus Egypt solidum C. lobosum Silurus sp. Rio Paraguay, South America Choanoscolex ab- Silurus sp. Rio Paraguay, South America scisa 288 ILLINOIS BIOLOGICAL MONOGRAPHS [288 Distribution of the Proteocephalids of Fish According to Continents The accompanying table lists the Proteocephalid species which are found on each continent. An examination of the table shows that in Europe there are 12 well known and 5 doubtful species. All are pecu- liar to Europe with the exception of P. macrocephalus which occurs also in North America along the Atlantic coast. In North America 9 species are known. Of these 2 are doubtful. All are peculiar except P. macrocephalus. From South America 4 species are recorded. All are peculiar. Likewise from Africa 3 species are recorded and all are peculiar. No species of this group have yet been reported from Asia or Australia, probably because but little parasitological work has been done on the fish of those continents. Nor are there any records as yet from the West or East Indies, Greenland, or Iceland. There has been but a singe collection record from Great Britain, where the parasites of fresh- water fishes seem to have had little attention. The records are as yet too meager to justify any broad conclusions as to the distribution of these cestodes over the larger land areas. One may expect to find the same Proteocephalid species in the hosts which are common to Europe and North America. One such case is known, namely, that of P. macrocephalus in Anguilla. Esox lucius which is common to both of these continents harbors one species in Europe and another one in North America. Other fish species occurring in both continents have apparently yielded no records in the literature. Distribution of Fish Proteocephalids according to Continents Continent Europe North America South America Africa Asia Australia Species of Proteocephalid found Proteocephalus agonis, P. cernuae, P. cyclops sp. inq., P. dubitis, P. esocis, P. fallax, P. filicollis, P. hemisphericus sp. inq., P. longicoUis, P. macrocephalus, P. neglectus, P. osculatus sp. inq., P. percae, P. sagittus sp. inq., P. salmonis-umblae sp. inq., P. skorikowi, P. torulosus. P. ambloplitis, P. exiguus, P. macrocephalus, P. nematosoina sp. inq., P. perplexus, P. pinguis, P. pusillus, P. salvelini sp inq., P. singularis. P. fossatus, P. macrophallus sp. inq., Corallobothrium lobosum, Choanoscolex abscisa. P. pentastoma, P. sulcatus, Corallobothrium solidum. No species reported. No species reported. 289] PROTEOCEPHALIDAE—LA RUE 289 Fish Haeboring Two or More Proteocephalid Species An examination of the complete list of fish Proteocephalids shows that there are fourteen host species which are reported to harbor more than one species of Proteocephalus. The data relating to these cases are presented in the accompanying table which names the hosts, their parasites and the distribution of the latter. A brief study of the table shows that of the fourteen host species ten are accredited with two species of Proteocephalus each, three with three, and one host with four. If from these numbers are deducted the instances of doubtfully identi- fied species and the species inquirenda there follow these results: Five host species each harbor two well described Proteocephalus species while one host harbors three. There are then but six undoubted cases of two or more species of Proteocephalus occurring in the same host species. An analysis of these six cases shows that in Lepisosteus platostomus the two parasitic species occur in the same locality, while in the cases of Amia calva, Esox lucius, and Perca fluviatilis the two parasitic species each occur in different localities. Likewise the three species of Proteo- cephalus found in Coregonus maraena occur each in different localities. The distribution of the parasites of Trutta fario is not known. One may conclude that two or more species of Proteocephalus may inhabit the same host species in the same locality or in different localities. The factors which determine this are not here shown. Species of Fish which harbor More than One species of Proteocephalus Host Proteocephalus species harbored Distribution of latter Amia calva Proteocephalus perplcxus Illinois River P. ambloplitis Lake St. Clair ; Lake Erie Lepisosteus plato- P. singularis Illinois River stomus P. perplexus Illinois River Salmo salvelinus P. longicollis Lakes Geneva and Lucerne, and locality not known P. salmonis-ufitblae sp. inq. Lake Geneva ; Germany P. torulosus (?) Lake Lucerne Trutta fario P. longicollis Locality not known P. neglectus Lake Geneva and Lake Lucerne Cristivomer namay- P. pusillus Lake Temagami, Ontario cush P. salvelini sp. inq. Lake Superior 290 ILLINOIS BIOLOGICAL MONOGRAPHS [290 Species of Fish which harbor More than One species of Proteocephalus (Continued) Host Proteocephalus species harbored Distribution of latter Coregonus maraena P. longicollis Greifswald; Rositten, East Prus- (C. lavaretus and sia; Lake Geneva C. fera) P. fallax Lake Lucerne P. percae Finland P. torulosus (?) Lake Lucerne Alburnus lucidus P. torulosus Germany ( ?) ; Lake Lucerne and Lake Geneva P. longicollis ( ?) Lake Lucerne Leuciscus leuciscus P. torulosus Germany (?); Bohemia; Lake Lucerne P. longicollis (?) Lake Lucerne Anguilla vulgaris P. macrocephalus Finland ; Germany ; France ; Switzerland ; Hungary ; Italy (Padua) P. hemisphericus sp. inq. Padua, Italy Esox lucius P. esocis Finland P. pinguis Maine; Michigan; Wisconsin P. longicollis (?) Lake Lucerne; Lake Balaton, Hungary Esox reticulatus P. pinguis Sebago Lake, Maine P. nematosoma sp. inq. Eastern (?) United States Gasterosteus aculeatus P. filicollis Greifswald and Berlin, Germany; Paris; Ireland P. percae (?) East Prussia Perca fluviatUis P. percae Germany; Finland; Sweden P. dubius Lake Geneva P. longicollis (?) Lake Lucerne Acerina cernua P. cernuae Prussia ; Lake Balaton, Hungary P percae (?) Locality unknown Proteocephalids Occurring in Two or More Species op Fish Twelve Proteocephalid species have been found to occur in more than one host of more or less close relationship. These species are as follows : Proteocephalus amhloplitis, P. cernuae, P. exiguus, P. filicollis, P. longicollis, P. macrocephalus, P. percae, P. perplexus, P. pinguis, P. pusillus, P. sulcatus, P. torulosus. In the following pages each of these species is discussed separately. The hosts have been investigated as to distribution and as to food habits in the hope that some clue might be found to the relations existing between host and parasite, a relation 291] PROTEOCEPHALIDAE—LA RUE 291 which in some cases is far different from that expected if the idea of the specificity of hosts be strictly adhered to. The data on distribution and food habits of the hosts have been abstracted and combined from several sources, chief of which are Nitsche (1909), Leunis (1883), Bridge (1904) and Boulenger (1904) in Cambridge Natural History, volume VII, Jordan and Evermann (1896-1900), and Forbes and Rich- ardson (1909). Proteocephalus amhlopUtis This species is known at present only from waters which drain into the St. Lawrence and the Red River of the North. Altho Professor Ward examined the proper host species from the Illinois River at Havana, 111., during the summer of 1909 his collections show that this parasite was not present there. The reported hosts are AmhlopUtis rupestris, Micropterus salmoides, M. dolomieu, and Amia calva. The first three hosts have much the same distribution over eastern and cen- tral North America to the Gulf of Mexico, while Amia calva occurs over a somewhat more restricted area. It is abundant, however, over a large part of the area in which the other hosts are found. In many localities two, three, or even four of the hosts live in the same waters. All four hosts are carnivorous, eating other fish and crawfish. Some of them eat other food in addition. These four hosts live in the same general region, frequently in the same waters, and have certain food habits in common. Such are the conditions to be expected if the hosts are to harbor a common parasitic species. One question remaining to be solved is this: why is this species not found in the Illinois River where these hosts live in large numbers? Since the Illinois River was connected with the Great Lakes in the recent geological period the failure to find this species in this river seems the more remarkable. Proteocephalus cernuae P. cernuae is known at present only from Prussia and from Lake Balaton, Hungary. The waters of Prussia drain to the Baltic Sea while those of Lake Balaton drain into the Danube and so to the Black Sea. The hosts of this species are Acerina cernua and A. schraetzer. The former has a wide distribution in north and central Europe and is also found in the Danube. A. schraetzer is confined to the Danube and its tributaries. Thus in the Danube the ranges of the two species overlap. Both species are carnivorous and both take bottom fauna. Under these conditions of distribution and food habits one would expect to find both species harboring the same cestode species. With further study of the collections this parasite will probably be found to have a much wider and a continuous distribution. 292 ILLINOIS BIOLOGICAL MONOGRAPHS [292 Proteocephalus exiguus P. exiguus has been found only in the Great Lakes. Its hosts, Coregonus (Argyrosomus) artedi, C. nigripinnis, and C. prognathus are all found in certain of the Great Lakes. C. artedi is in all the Great Lakes and neighboring waters, and north to the Arctic regions, exclu- sive of Alaska. C. nigripinnis is found in the small lakes of Wisconsin and Minnesota and in Lake Michigan. C. prognathus occurs probably in all the Great Lakes in deep water. Thus in Lake Michigan, at least, these species are all found. As to food habits but few data may be found for C. prognathus and C. 7iigripinnis. C. artedi feeds on Ento- \/' mostraca, small molluscs and crustaceans, with larvae of insects and other animal forms including bottom fauna and spawn of the common white fish. It seems probable that the other species take many of these same food elements. Under these conditions the finding of this species in three closely related hosts is not remarkable but is to be expected. Proteocephalus filicollis This species is known only from the lower reaches of the streams flowing into the Baltic Sea, into the North Sea and the waters adjacent thereto. It apparently does not occur in the Alpine lakes. Its hosts are Gasterosteus aculeatus and G. pungitius. The latter is found all over north Europe (not in south Germany) and in North America as far southward as the Great Lakes region. G. aculeatus has a more restricted distribution being confined to the fresh and brackish or saline waters of Europe with the exception of the Danube drainage system. Thus the two species occupy* north Europe in common. In food habits the species are much alike. Both are voracious plankton feeders; both take also fish-eggs and fry, and bottom fauna. These are the conditions which one would expect to find if the two species harbor the same para- site species. Specimens of G. pungitius from North America should be examined in order to learn whether they harbor the same species of parasite as the European specimens. Proteocephalus longicollis This species has a wide distribution in Germany and is known also from Switzerland. It is unknown in southern Europe, Russia or in France. It has been reported from Hungary, probably as the result of \y a misdetermination. Its reported hosts are mainly salmonids tho the V list includes one esocid, one percid, and three cyprinidg. The accom- panying table names the hosts and shows the distribution and food of each. An examination of the table shows that in a general way these 293] PROTEOCEPHALIDAE—LA RUE 293 host species overlap greatly in their distribution. Several of the species occur in the same waters. Some live only in the depths of deep lakes while others live only on the surface ; others live in brooks and streams, still others as Perca fiuviatilis are ubiquitous. One host, Trutta trutta, lives in salt water and enters fresh water to spawn. Thus tho a species may have a wide distribution its habitat may be narrowly restricted. In the restricted habitat the food of the species is likely to be more or less restricted. Surface fish do not get the same kinds of food as do those that live on the bottom. A survey of the table shows that all the hosts of P. longicollis de- pend on animal food tho some of them may take plant food on occasion. Certain species are much restricted as to food, so much restricted, in- deed, that it may be s^id with some degree of certainty that some of the plankton forms must be carriers of this infection. Coregonus wart- manni and C. wartmanni nohilis are referred to as hosts which eat plankton exclusively. It is also apparent that if the records be true some other invertebrates must be carriers of the infection for several species are found which do not feed on plankton. Some molluscs may play a part as carriers. Still other fish of the list eat fish almost ex- clusively hence it must be that fish can serve as intermediate hosts for this parasite. It has already been shown in numerous instances that the primary host may also serve as the intermediate host for Proteocephalid species. If one considers now the different habitats and the various kinds of food taken in them it must be admitted that the evidence points toward a confusion of several species under the one name. In the opinion of the writer the validity of many of the records is doubtful. A comparative study of Proteocephalids taken from all these hosts of different localities would perhaps settle these questions as to hosts of P. longicollis. Granting that all the salmonids of the list are hosts of this parasite then on the basis of food, distribution, and habitats it seems that the non-salmonids might likewise be its hosts. However, it has seemed that these records relating to the non-salmonids rest on too slender a foundation. Without an exception these records are those of Nufer (1905) whose work has been discussed in the section dealing with the description of P. longicollis. Parasites of these non-salmonids, espe- cially from Lake Lucerne where Nufer was at work, ought to be sub- jected to a careful comparative study. This would doubtless establish or overthrow the validity of the records. 294 ILLINOIS BIOLOGICAL MONOGRAPHS [294 n o n o s H H tOW) o 5 5 3 s ^f 8^=3 S s S" l-i a"o ^ 3. e o a 8 a s n o s: • -^ a o. X o to CO Co i a — 2. 8 2 8-r 8 S. to -• i" s 8 C 5* Co a as 8 a '-a to o >• O :^ :^ n r~ a 2 ^ ^ 3"»-0 S3 UJ f6 W3 ? p 3- -^ p O to p V; 0_ <0 p' "-l <^ ►.. to p t: 3 to ^ tr p n ^K« "3 o o o- og. O ve; P ^ 3 5. — w 3 _S" Ul ^ S O ... O w p i-fr» "> i_i (K? ^3 P rD O 3^o rl- CO CO p p O CO "8 p rt O - CO >-f. 3 SLo- O fD 1 — 3 S- o "" E. *< cr 3 • C o 3 5'p "» o p 3 3 « " o « n Ul O 3 3 O 2 w «= -.5* 3 3 p rt 3 P p en v: 3 m n p p o-o S o 3. 3 S. CO 3 ' HT <-<• ft -i CO p cr ?r to rt rt • c 2 t« 2. 5' 5*' c o' 3 01 p g O p O 3 ^ o M 3.^q n 3 n o tn C/)0 " 3 C3 5 3 - 5L o*p 3 3 no r. -r c CO n 5" H.E^ X X X X Fish X Spawn and * fry O O o X X X X X Plankton X X X Bottom fauna X X X X Molluscs X X Crustacea X X Worms X Insect larvae rro > > rt o "l' -n' o> rt 1 . 3- to ir o o *§ -1 3 2 Other food P i^ rti ?» rt •-»> 1 rt 3 3 n CO tfl /~^0. n 2 -»» >•. o o ^-'S O) M 5- 295] PROTEOCEPHALIDAE—LA RUE 295 c c o O 13 O O o o to •" It; E •0 pooj jamo 13 "o 3 ceo si to to c to «2 V ^o ^o Jf B b-^ C I^ o to Ot t— 1 to c Cfl (O 3HAJBI X JDdSUI SUldO/^ X p o o fa B33B;snJ3 X SDsniioj^ X X X BUnBJ uio;;oa UOJ31UBIJ n.. X pUB UMEdg X X HSiJ X X X ^ sS c u "Sis' •0 C OJ v .s V o CD ll u JC u > .< ll o c 3 W to "rt •o c a to to O o •o2 o c c e-o rt g u -r; C 3 a o c o c o. o "o 4. Ml ^^ n 30Q to _ 3 'u to >> 2 o c to o c to c« J3 « w to u 1o 'rt C 3 O 10--; »-• Q. ? u g . to c cfl • s o « 5 c 2 o o to "to o . rt to C u y u XI C c-^ dj u ^'U ^ ^ — o t( u tfl t; ll c u s u 8 •o < ."5) '' — .5 .5 n ►J w 0.1 3 s O to O 4> S 13 c5 to .2 0. lO to o Sin 15 0) r* H 3 •"2 1* ^•2 3 <^ *5 ll to ^ H^ 9 .5^ 2 o>* wo*" S*^ ^■^ c o a 1^? t/) U L) L> U4 a. ^ to •-1 296 ILLINOIS BIOLOGICAL MONOGRAPHS [296 Proteocephalus macrocephalus This species has the widest distribution of any known Proteocepha- lid. It has been taken in many localities of northern, central and south- ern Europe and from two localities in eastern North America. Its hosts are Anguilla vulgaris and A. chrysypa. The former has a wide range over most of Europe, north Africa and temperate Asia. It is lacking in the Black and Caspian Seas. By some authorities this species is thought to be found also in North America. Others, including Jordan and Evermann (1896-1900) make the American form a separate species, calling it A. chrysypa. This species occurs over the most of North America east of the Rocky Mountains, including Mexico and the West Indies. The food habits of the two species are alike. They are vora- cious, and act as scavengers, preferring dead fish or other animal refuse. In view of their close relations and their similar habits it is not surpris- ing that these species harbor the same species of parasite. Proteocephalus percae The geographical distribution of this species is imperfectly known. Up to the present time it has been taken only in East Prussia, Finland 'and Sweden. It has not yet been reported from the Swiss lakes tho two of its host species are abundant in that region. These hosts are Perca fluviatUis and Coregonus maraena (fera). The appended table gives the data as to hosts, their distribution and food habits. An exam- ination of the table shows certain points of interest. Perca marina which Miiller gave as a host of this parasite is little known, nor is Perca norvegica which Rudolphi said was the host of Miiller 's parasite. The remaining host species overlap in their distribution. Likewise their food habits overlap to a certain extent. All eat bottom fauna tho Perca ftuviatUis preys more on other fishes than do the other hosts. The food habits of P. fluviatUis and Coregonus maraena show close resemblance. These two species are known to harbor the species which Schneider (1905) describes as Ichthyotaenia percae (Miiller). Acerina cernua and Qasterosteus aculeatus may harbor this parasite but it seems doubt- ful. These two species are known to harbor Proteocephalus cernuae and P. filicollis respectively. It seems that there may have been a mis- determination. The parasites of these two hosts and of Coitus quadri- carnis should be subjected to a re-examination. 297] PROTEOCEPHALIDAE—LA RUE 2ff7 Hosts of Proteocephalus percae, their Food and Distribution Host species Distribution Food habits Perca norvegica=Perca ma- No data Xo data nna Perca fluviatilis Lakes and rivers of all Eur- Carnivorous, eats fish ope and northern Asia (largely species of Al- bumus), amphibia, snails, insects and worms Coregonus maraena=(.C. In deep water of large lakes Small "fish, bottom fauna. lavaretus and C. fera) of Alps, Bavaria, and near Plankton, small Crustacea Baltic coast; Baltic Sea and molluscs Acerina cemua In brackish and fresh wa- Fish eggs and fry, bottom ters of north and central fauna, rooting in the bot- Europe to Siberia; in tom for last ENanube. Prefers deep water with sandy bottom Gasterosteus aculeatus In fresh and brackish or A plankton feeder; eats salt water of all Europe fish-eggs and fry, also except Danube bottom faima Coitus quadricomis Arctic regions south to Bal- No data on food. A close tic Sea, westward to relative, C. gohio, eats Greenland molluscs and spawn. Proteocephalus perplexus This species is known at present only from the Illinois River at Havana, 111. Leidy's notice (1886) of Taenia fiZicoUis found in Amia calva from North Carolina may refer to this species. The hosts are Amia calva and Lepisosteus platostomus. The former is common in rivers and lakes of central and southern North America, including lakes Huron and Erie. The latter host, Lepisosteus platostomus, occurs throughout the Mississippi valley but is said to avoid the smaller streams. Thus in the Mississippi valley the two hosts have a common range. Amia feeds on fish, crawfish and molluscs while the other host takes fish almost exclusively. If Lepisosteus includes Amia in its diet it may secure its infection from Amia which may perhaps serve as both primary and secondary host. On account of its armor it is not at all likely that the gar serves as food for Amia. It has seemed rather re- markable that this parasite was not found in Amia calva of the Great Lakes. A most careful examination of the material collected by Pro- fessor Ward in the course of his work on the Great Lakes has shown that it does not exist there. Likewise it seems remarkable that the other carnivorous fish of the Illinois River, such as the bass, do not have this infection. Some of these fish eat very much the same food as Amia. 298 ILLINOIS BIOLOGICAL MONOGRAPHS [298 Proteocephalus pinguis P. pinguis is a North American species found in widely separated localities. It has been found in small lakes of Maine, Michigan and Wisconsin, It has not yet been found in the Great Lakes. Further collections may show a much wider distribution for this species. The hosts, Esox lucius and E. reticulatus, have a wide distribution. Esox lucius is a cosmopolitan species of the northern hemisphere, occurring in the fresh waters of Europe, Asia and North America. In North America its range is from Alaska south to the upper Mississippi valley, east of the Rockies to the Potomac. Esox reticulatus is common east and south of the Alleghanies to Louisiana, and Arkansas. The ranges of these hosts are common east of the Alleghanies to the Potomac river. Both hosts are voracious carnivores, eating fish, frogs, crawfish, mice, reptiles, water birds, and larger insects. That these two host spe- cies harbor the same species of Proteocephalus is then not remarkable. Since, however, Esox lucius is common to Europe and North America one might expect to find it harboring the same species of Protecephalus in both continents. Such does not seem to be the case. This fact sug- gests that these two species, P. pinguis from North America and P. esocis found in the European Esox, have arisen as varieties of the same species or that the host upon going into the new region, either Europe or North America, has acquired a new species of parasite. Proteocephalus pusUlus This species occurs in Sebago Lake, Maine, and Lake Temagami Ontario. Its hosts are Salmo sehago and Cristivomer namaycush. These two salmonids live ou^y in fresh water and their habitats overlap to a certain extent. Salmo sehago, according to Jordan and Evermann (1896), occurs in Sebago Lake and northward, in lakes, rarely entering streams. Cristivomer namaycush lives in the lakes of New York, New Hampshire and Maine and westward to the headwaters of the Columbia and north to the Arctic circle (Forbes and Richardson, 1909). Both fish are predaceous, living largely on fish. Professor "Ward's records show that in Sebago Lake Salmo sehago was feeding on Osmerus mor- dax. Records are too meager to allow the making of any general conclusions. Proteocephalus sulcatus This species is known only from the Nile River, from two widely separated hosts, namely Polypterus endlicheri and Clarotes laticeps. The former is one of the Polypteridae, a Crossopterygian, while the latter named host is a Silurid, of the order Teleostei. Both hosts occur in the Nile. The food habits of Polypterus endlicheri are not well known. One species of Polypterus feeds on small teleosts while others 299] PROTEOCEPHALIDAE—LA RUE 299 take batrachians and crustaceans in addition to the fish. This species is no doubt carnivorous in habits. The writer is unable to find anything about the food of Clarotes laticeps. It seems probable, however, that it is a carnivorous species as are many others of the Siluridae. That this parasite is able to find the proper conditions of life in two species as widely separated as are these seems remarkable altho not more remarkable than that Amia calva may serve as the host of a species characteristic of the Centrarchidae. It has, however, been pointed out in the descriptive part of the work on this species that there seems to be some reason for believing that two species have been confused under the one name. Proteocephalus torulosus This species is known only from northern and central Europe, chiefly from the Baltic drainage. Its hosts are chiefly cyprinids. All U^ the earlier reports record it only from cyprinids. During the last few years it has been reported from Salmonids, four species, and from Perca '"" fluviatilis and Lota vulgaris. A table is appended showing the names of the hosts as reported, their distribution, and their food. As to food the data are very fragmentary and not specific yet they are of interest. An examination of the table shows that the hosts are common in the waters of the lakes and streams of central and northern Europe. Some hosts are of wide distribution, others more or less restricted. Many of these hosts occupy the same waters, some as surface dwellers, others as bottom dwellers, some in the deep lakes, others in the small streams, while still others occur in the brackish bays and inlets of the Baltic coast. Thus the habitats are quite varied. The food taken by the host varies to a large degree with the habitat which the host prefers. Thus from the table it is found that the food habits of the hosts listed are very different. Some are exclusively plankton feeders, others feed largely on bottom fauna or bottom fauna with plankton. Still other hosts are largely eaters of fish. If the food of the two groups of hosts, cyprinids and non-cyprinids, be considered it is noted that each of the latter group takes several kinds of food. This statement applies only to those non-cyprinids the food of which is known. Each of the cyprinids, however, takes but few kinds of food. The table speaks for itself. The cyprinids of the table are chiefly feed- ers on bottom fauna. Plankton forms a large part of the food of three, and fish of two of these hosts. Certain elements in the food such as air- borne insects, birds, plants and probably also amphibians (semi-terres- trial forms especially) do not function as intermediate hosts for Pro- teocephalus species. For this reason they need not enter into this discussion. JOO ILLINOIS BIOLOGICAL MONOGRAPHS [300 O o c pooj aaqJO 3BA4BI pssuj SUMO^ B3DBJSnJ3 sDsniioj^ ^Bunej uioj;oa UOJ3JUBIJ pUB UMBdg qsij « g C.5 Is ""Q O <" o '«-' bo c -^ o 3 rt u *' I- fc, o o e o < en X X X X X X X X X X o s 3 o 3 J3 o V o 1^- •^.2.^3 ^ O' V Xi CO o 'a ' c ® W .S fc « c Js 2 o o B 5 < ^^ .3 ^ C > g g-O o c c j: s "" 5^ 2 2 1 c *J rt "3 — oc c; r -y) c < ^ O rt — U o c c ^'« Cli<-> o c i; 3 =» o . 2 ? tn o « C> V? O U ^ *" — ^ £~Z o cs f* o = = 2 o F. boS ■J-. CQ (y I- ^-2 Z.'' « cB •^ •^, bO u u *-• a MX y OJ — ^ O w c > CO u _ :2 » •2 -2 ^ =J n U « to "J rt 4. t» . V o c ? i .2 y ^ ^ 301] PROTEOCEPHALIDAE—LA RUE 301 «.J. "O •o 3 C o o O rt 54 c o o MH 'S'^'c c o n o CTt •pooj jamo c o 2 CO •a O, (ll o o s :z ;^ "Z, - »v 52 g* bo > i> C rt T3 ^ pq o n o c tn S w "cO o in u « CO o ^J2 t« oxiPQ bO C o |_ C "'sill 2 ""^^ M-1 ^15 r- O („.3 3 ct3 4> C •V c "> . «>.2 1 u <; ,_1 J Q J ta CO 8 S 8 i a i in O i-r-i «-5 O. 8 1 a 3 .a 1 ii ■I <*> c s o c> •S «0 5 8 5 a » o •l,^ o , , o ^ O e> CQ U L) L) to 14. ►-J 302 ILLINOIS BIOLOGICAL MONOGRAPHS [302 How can the infection of so many species of fish with this parasite be explained? For the sake of the argument it is granted that all these species are suitable hosts for this parasite. If all these species are to be infected it is necessary that some of the invertebrates included among plankton forms, bottom fauna, and molluscs must be able to serve as intermediate hosts of this parasite. The fish which become infected from eating these invertebrate hosts may likewise become self-infected and so serve as intermediate hosts. If such fish are then eaten by the predaceous fish of the list then the latter may become infected. Thus it is possible to offer explanations that will cover the whole question of the source of infection for these hosts which have such different food habits. The analysis, however, is not very convincing. The more plau- sible explanation is that several species of parasite are being dealt with under this one name. It seems not improbable that the parasites of the cyprinids may belong to at least two or probably three species while the jion-cyprinids may or may not harbor any of these. Further inves- tigations on the parasites of the hosts of this list should be undertaken with the view of settling some of these questions. CONCLUSIONS A careful analysis of the extensive data presented in this section shows that species of Proteocephalus may occur in multiple hosts in the following combinations: 1) A species of Proteocephalus may occur in different host species of the same genus. Five species are limited exclusively to various species within the same host genus. ,2) A species may occur in the different genera of the same family. One case. 3) A species may occur in the members of closely allied genera, i. e. of the same order. Four cases are known. 4) A species may occur in families of very wide relationships, i. e. of different orders. There are two cases of which one is doubtful. It is further shown in this section that when a species of Proteo- cephalus occurs in multiple hosts under any of the combinations above suggested the host species have a continuous distribution. The only apparent exception to this rule is in the case of AnguUla vulgaris of Europe and A. chrysypa of North America, both harboring P. macro- cephalus. In this case, however, the exception is apparent and not real for these two forms are perhaps no more than varieties of a cosmopoli- tan species. Analysis of the data presented in this section also shows that in many cases of multiple hosts the food of the different host spe- 303] PROTEOCEPHALIDAE—LA RUE 303 cies is alike in some or all of its elements tho the proportions of these elements may differ widely. Since the infection of the host is only accomplished through the food eaten a general statement may be made thus: The 'parasitic infestation of the host is determined hy the food eaten. The character of the food is determined by the environment and largely by the habitat preferred by the host. The apparent excep- tions to the above conclusion are found in those cases where a group of species acting as hosts to a single species of parasite feed on very different elements of food. In each of these cases the probability has been pointed out that there has been a confusion of species under one name. If such a confusion does not exist then there is evidence of the remarkable adaptability of the larval stages of the parasite to the life conditions of a large series of invertebrates and fish. Both of these possibilities should be investigated. The evidence as presented in this section is not in favor of a strict adherence to the idea of the specificity of parasites. This idea cer- tainly does not hold for any of the better known species of Proteoceph- alus for which quite a number of collection records are available, but it seems to hold for a number of species for which there are but one or two collection records and for species which are imperfectly known. To apply the idea to these cases is not justified. To break away en- tirely, however, from the idea of specificity of parasites would be a rash step, indeed, for certain cases have been well established which show conclusively that for certain hosts, other than those considered in this paper, certain species of parasites are specific. Such cases can only be determined by many records of collection and then are to be relied upon only after careful infection experiments have been worked out. To apply the idea of specificity of parasites without having taken these precautions is not justifiable. In working through the data on distribution of Proteocephalus species which have multiple hosts one notes that in many cases the range of the parasite may be greater than the range of some of its hosts. This is well illustrated by the range of P. longicollis which has a far wider distribution than some of the spe- cies of Coregonus in which it occurs. Some of these species occur in just a few lakes while P. longicollis is known from many localities of northern and central Europe. So also the range of P. macrocephalus is greater than that of either of its hosts. An explanation for this wide distribution of the parasite may be stated thus: The parasite may have a better means of dispersal than the host. The distribution of fish Proteocephalids may be widened in the following ways: They are carried by the primary host which voiding feces as it wanders about scatters the eggs of the parasite that 304 ILLINOIS BIOLOGICAL MONOGRAPHS [304 may infect suitable intermediate hosts. The latter, vertebrates or in- vertebrates, may migrate or be carried by currents to farther limits. New hosts may be infected and these on their migrations may carry the infection beyond the original limits of distribution of the parasite. The introduction by man of fish into new regions is a method of widening the range of a parasite. It is suggested as a further possibility that fish-eating birds at the time of migration may carry the eggs of the parasites ingested with the fish for some distance and these eggs being discharged with the feces into the water may infect suitable intermedi- ate hosts. This method of dispersal could be possible only if the eggs of the parasite thus eaten are capable of withstanding the vigorous digestive action of the bird. Experiments would be required to deter- mine the value of this method. Families op Fish from Which Proteocephalids are Known The data on this subject are collected in the accompanying table. It is there shown that Proteocephalids are known from fifteen families of fish of the group Teleostomi and representing the orders Crossop- terygii, Chondrostei, Holostei, and Teleostei. The writer follows the classification of Bridge (1904) and Boulenger (1904), Vol. VII, Cam- bridge Natural History. Of the fifteen families ten belong to the order Teleostei. The latter contains by far the larger number of fresh water fishes. Proteocephalid species are as yet unknown from the Dipnoi. A comparison of the collection records and of the accompanying table shows that certain species of parasite seem to be characteristic of cer- tain families of fish. Those ,cases in which the parasite has been recorded but once or twice probably should not be considered as characteristic of their host families. Among such cases are to be mentioned the occur- rence of P. pentastoma in the Polypteridae, P. skorikowi in the Acipen- seridae, P. singularis in Lepisosteidae, etc. There are certain species which have been recorded several times and the majority of these times from a certain family of fish. Such species are to be considered as being characteristic for the family. The species which fall in this group are: P. longicollis and P. exiguus, characteristic of Salmonidae; P. torulosus of the Cyprinidae ; P. macrocephalus of Anguillidae ; P. pinguis of the Esocidae; P. fUicollis of Gasterosteidae ; P. ambloplitis of Centrarchidae ; P. percae and P. cernuae of the Percidae. The re- maining species are too little knoA\Ti to justify an attempt to determine this relationship. 305] PROTEOCEPHALIDAE—LA RUE 305 Families of Fish from which Proteocephalids are Known, the Species of the Latter and the Frequency of their Occurrence Frequence Order Family Species of parasite of occurrence Crossopterygii Polypteridae Proteocephalus sulcatus I P. pentastoma 2 Chondrostei Acipenseridae P. skorikowi I Holostei Amiidae P. per plexus I P. ambloplitis 2 Teleostei Lepisosteidae P. singularis I P. perplexus I Clupeidae P. agonis I Salmon idae P. longicolHs 20 or more P. fallax I P. neglectus 2(?) P. pusillus 2 P. exiguus 3 P. percae I P. salmonis-umblae (sp. inq.) 2 P. Cyclops (Immature and poorly known) I P.. salvelini (Immature and poorly known) I P. torulosus (Doubtful deter- mination) 4 Cyprinidae P. torulosus 18 or more P. sagittus (sp. inq.) I P. longicollis. (Doubtful de- termination 3 Siluridae P. sulcatus I P. fossatus I P. osculatus (sp. inq.) 2 Corallobothrium solidum I C. lobosum I Choanoscolex abscisa I Anguillidae Proteocephalus macrocephalus 10 P. hemisphaericus (sp. inq.) I Esocidae P. esocis I P. pinguis 3 P. nematosoma (sp. inq.) 2 P. longicollis (Doubtful de- termination) I Gastrosteidae Proteocephalus filicollis 10 306 ILLINOIS BIOLOGICAL MONOGRAPHS [306 Frequence Order Family Species of parasite of occurrence Gadidae P. torulosus (Doubtful de- termination) I Centrarchidae P. ambloplitis 4 Percidae P. percae P. cernuae P. dubius P. longicollis (Doubtful de- termination) 5 3 I I Cottidae P. percae (needs confirmation) I Cichlidae P. macrophallus I Frequency of occurrence in the above table has been determined by taking the sum of the number of localities from which the species has been reported (including times from same locality) or in case it occurs in more than one host in one locality the number of host species is added. Numbers are approximate. LIFE HISTORY OF THE PROTEOCEPHALIDAE Since the appearance of a previous paper by the writer (La Rue 1909) in which he reviewed the literature on thus subject and in which he outlined certain feeding experiments which had for their object the solution of the problem of the life history of the cestode infesting Amblystoma tigrinum but little additional data have appeared on the life history of Proteocephalids. Barbieri (1909) found that Bythro- trephes and Leptodora act as intermediate hosts for Proteocephalus agonis. So far as can be ascertained there are no other data in the recent literature of this subject. Fuhrmann (1903) outlined the life history of Proteocephalids, Several of the older investigators have mentioned the finding of plerocercoids in the livers of fish which har- bored species of Proteocephalus ia the intestine. The writer (La Rue 1909) recorded the finding of many plerocercoids in the tissues of the salamander, Amblystoma tigrinum, and the positive results obtained from feeding these plerocercoids to uninfected hosts. The probability was there suggested that salamanders might become infected through the eating of infected salamanders. There is at present no reason for changing this view. While making an examination of a specimen of Natrix rhomhifer the wTiter found numerous encysted plerocercoids in the tissues of the alimentary tract and of the liver. Since many snakes 307] PROTEOCEPHALIDAE—LA RUE 307 are accidental or intentional cannibals it is possible that the eating of one snake by another may be one method of infection. Since also this species of snake lives largely upon fish and frogs one should look to these food animals for the intermediate host of its cestodes. No avail- able records deal with this method of infection. From the data presented by various workers it seems probable that the life history of the Proteocephalids is essentially as follows : The eggs and some of the ripe proglottids bearing eggs are voided by the host into the water where they are eaten by an invertebrate, perhaps a worm, an insect larva, or a crustacean, or possibly the eater is a verte- brate, fish, snake or an amphibian of the same species as the host or different. If the invertebrate or vertebrate furnishes a suitable habitat for the development of the parasite the six-hooked embryo establishes itself and from it develops a plerocercoid about which the host produces a cyst. If the intermediate host be eaten by a vertebrate which furnishes a proper habitat for the adult parasite the plerocercoid when it is released by the action of the digestive juices from its intermediate host and from its cyst passes to the intestine and develops into the adult tapeworm. If the final host engulfs material containing eggs of the cestode harbored by itself or its congeners or perhaps by members of other species the host becomes infected with the plerocercoids and so it may function as a secondary as well as a primary host for its parasitic species. Cannibalism may be a means in the spread of the parasites harbored. The problems connected with the life-history of these para- sites must ultimately be settled by experimental methods. ORIGIN OF THE PROTEOCEPHALIDAE This work has thrown some light on the relations of the genera and species of Proteocephalidae to one another. It is of interest to attempt to point out the probable relations of the family to other cestodes. Like many other cestodes the members of this family were once included in the great genus Taenia. That, however, was before the internal structures of these cestodes were well known and it seems that the basis for this classification was the apparent similarity of the suckers. It is now evident that the Proteocephalids are most closely related struc- turally to the cestodes of the order Tetraphyllidea. A marked agree- ment in the general arrangement of all the internal organs of Tetraphyl- lidean cestodes is to be noted. In these respects the Proteocephalids do not agree with the Cyclophyllidea. In external features alone the Proteocephalids resemble the Cyclophyllidea more than the Tetraphyl- lidea. This is due to the marked simplicity of the heads and suckers of the Proteocephalids and the usual hemispherical form of the suckers. N^ 308 ILLINOIS BIOLOGICAL MONOGRAPHS [308 The resemblance of the heads and suckers of Proteocephalids to those of Cyclophyllideans is, however, more apparent than real. The heads of the latter group are not readily mobile. Except in those eases where a protrusible rostellum is present the heads do not change shape much. The suckers, moreover, are strongly cupped at all times and are not much moved by the muscles of the head. The heads of the Proteocephadids are, as the name implies, ever changing. They undergo a multitude of changes of form and appearance. The suckers may be strongly cupped when contracted or the cavity may be entirely obliter- ated by the stretching of the sucker. The suckers are very mobile, being capable of being pushed out, forward or backward or laterally, and retracted. This movement of the suckers adds greatly to the protean character of the head. The whole anterior part of the head may in some species be retracted within the swollen bulbous basal part of the head. In respect to the movement of the head and the action of the suckers the Proteocephalids resemble the other Tetraphyllideans. Another point of resemblance between the Proteocephalids and the other Tetraphyllideans is the presence of a degenerate fifth sucker in many species of the two groups. In the Cyclophyllidea a somewhat similar appearing structure is to be found in certain species. Here it is probably a degenerate rostellum and not a degenerate fifth sucker. Structurally the Proteocephalidae are to be considered as being closely allied to the Tetraphyllidea while their relationship to the Cyclophyl- lidea is distant. The relation of the Proteocephalidae to the other groups of cestodes is remote. The members of the order Tetraphyllidea other than the Proteocephalidae and Monticellidae are characteristic i/ parasites of marine fishes, 'mostly selachians. The freshwater fishes have arisen from the marine fishes and their parasites have doubtless arisen from the parasites of the marine fishes, the Proteocephalids coming from a Tetraphyllidean ancestry. Just which fish species was responsible for the bringing of this Proteocephalid stock into fresh water is a matter of conjecture. Since this group of parasites is found to be parasitic in members of so many families of freshwater fish it may be inferred that some of the older and more primitive Teleostomi, a Ganoid, brought into the freshwater environment a Tetraphyllidean with a simple type of head and suckers, altho this simplicity may have been a later evolution. Another hypothe- sis is that these parasites were introduced into fresh water by representa- tives of several families of fish such as the Salmonidae, the Gadidae, or the Anguillidae. Among the Salmonidae certain species have acquired the permanent habit of remaining in fresh water while others enter fresh water only to breed. The species of AnguiUa go back to salt water 309] PROTEOCEPHALIDAE—LA RUE 309 to breed and hence each individual spends part of its life in a marine environment. The Gadidae are characteristic salt water fish altho the members of one genus, Lota, have permanently established themselves in the freshwater environment. At the present time there is no evi- dence to show that species of Salmonidae or of Anguilla at the time of their migrations introduce into freshwater parasitic species which are capable of establishing and maintaining themselves in the new environ- ment. Ward (1910) has pointed out that Salmo sehago, landlocked in lakes of eastern North America, has a parasitic fauna that is charac- teristic of its freshwater environment. It is evident then that what- ever parasites this species brought with it from its former marine environment were unable to establisli themselves. This failure may have been due to a lack of proper intermediate hosts. These considerations lead to a possible explanation which depends on the possibility that the intermediate host species (a fish or perhaps an invertebrate) of a Tetraphyllidean acquired the habit of living in brackish and finally in fresh water. The fish species which normally made this intermediate host its food may also have made this change of environment or perhaps other fish began to prey on the intermediate host. Under these conditions the parasite might have become established in the new environment. It also seems probable that new intermediate hosts might have been acquired. The acquiring of a new host depends not on the anatomical structures of the host but upon its physiological properties and upon its habits of feeding and its environment. The fact that the head and the suckers of Proteocephalus singularis strongly resemble these structures in certain species of other families of Tet- raphyllidea is suggestive. The host, Lepisosteus platostomus, is more- over a primitive fish of strong carnivorous habits. The Lepisosteidae have long been established in fresh water. It is here suggested that some member of this family may have been responsible for the intro- duction of Proteocephalids into the fresh water environment. The Pro- teocephalids of amphibians and aquatic reptiles may have been acquired in the course of development from some fish-like ancestor or it is more probable that they have acquired their Proteocephalid fauna from eating intermediate hosts (invertebrates or fish) infected with larval Proteo- cephalids. In this connection it is of interest to note that the head of Crepidobothrium, found in the Boidae, is the most primitive of all the heads of Proteocephalids of amphibians and reptiles. That is to say, it is more like the heads of other Tetraphyllideans than are the heads of its congeners. The Boidae are considered to be somewhat primitive snakes. 310 ILLINOIS BIOLOGICAL MONOGRAPHS [310 BIBLIOGRAPHY ACHARIUS, E. 1780. Anmarkningar vid Herr Martins Ron, rorande en besynnerlig mask hos norsen. K. svenska vetensk. akad., n. Handl., i :49-5S, 2 pi. 9 fig. Baird, W. i860. Description of some new species of intestinal worms (entozoa) in the collection of the British Museum. Proc. Zool. Soc. Lond., 1860:446- 448. 1861. Idem. Ann. & Mag. Nat. Hist., (3) 7 :228-23o. Barbieri, C. 1909. Ueber eine neue Species der Gattung Ichthyotaenia und ihre Verbreit- ungsweise. Centrbl. Bakt. u. Parasit. (i) Originale, 49:334-341, 8 fig. Barrois, T. 1898. Sur quelque ichthotenias parasites des serpents. Bull. soc. sci. agric. et arts, Lille, 2:4. Batsch, a. J. G. C. 1786. Naturgeschichte der Bandwurmgattung uberhaupt und ihrer Arten insbesondere, nach den neuern Beobachtungen in einem systematischen • Auszuge. 298 pp. ,5 pi. 169 fig. Halle. Belungham, O'B. 1844. Catalogue of Irish entozoa, with observations. Ann. & Mag. Nat. Hist, 14:317-323- Benedek, p. J. Van. 1861. Memoire sur les'vers intestinaux. Compt. rend. Acad, sci., Paris. (Supplement), 2, 376 pp., 27 pi, Benedict, H. M. 1900. On the structure of two fish tapeworms from the genus Proteoceph- alus Weinland, 1858. J. Morph., 16:337-368, pi. 16, 35 fig. De Blainville, M. H. D. 1828. Vers. Diet. sci. nat., 52:365-625, pi. 27-28. Bloch, M. E. 1782. Abhandlung von der Erzeugung der Eingeweidewurmer und den Mitteln wider dieselben. 54 pp. 10 pi., Berlin. BOULENGER, G. A. 1904, Systematic account of Teleostei. Cambr. Nat. Hist., 7:541-727. Braun, M. 1894-1900. Vermes: Cestodes. Bronn's Klassen und Ordnungen des Thier- reichs, 4, Abt. i, b. Bridge, T. W. 1904. Fishes. Cambr. Nat. Hist., 7:141-537. 31i] PROTEOCEPHALIDAE — LA RUE 311 Carus, J. V. 1857. Icones zootorpicae. Erste Halfte : Die wirbellosen Thiere. 32 pp. 37 fig. 23 pi. Leipzig. Cholodkovski, N. a. 1908. Ueber eine neue Tiinie des Hundes. Zool. Anz., 33 :4i8-42o, 4 fig. COBBOLD, T. S. 1858. Observations on entozoa, with notices of several new species, includ- ing an account of two experiments in regard to the breeding of Taenia serrata and T. cucumerina. Trans. Linn. Soc. London, 22:155-172, pi. 31- 33, 85 fig. Creplin, F. C. H. 1825. Observationes de entozois. 86 pp. i pi. 17 fig. Gryphiswaldiae. DiESING, K. M. 1850. Systema helminthum. i, 679 pp. Vindobonae. 1851. Idem. 2, 588 pp. Vindobonae. 1856. Zwanzig Arten von Cephalocotyleen. Denkschr. k. Akad. Wissensch., math.-naturw. CI., Wien, (i), 12:23-38, pi. 1-4. 1864. Revision der Cephalocotyleen. Abtheilung Cyclocotyleen. Sitzungs- ber. k. Akad. Wissensch., math.-naturw. CI. Wien, (i), 49:357-430. DUJARDIN, F. 1845. Histoire naturelle des helminthes ou vers intestinaux. 654-I-15 pp., 12 pi. Paris. Forces, S. A. and Richardson, R. E. 1909. The fishes of Illinois, cxxxi -f- 357 pp. Fric, a., and Vavra, V. 1901. Ueber Lebensweise, Nahrung und Parasiten der Fische der Elbe. Untersuchungen iiber die Fauna der Gewiisser Bohmens. V. Untersuchung des Elbeflusses imd seiner Altwiisser durchgefiihrt auf der iibertragbaren zoologischen Station. Arch, naturw. Landesdurchforsch. von Bohmen, 11:111-118. Fritsch, G. - , » 1886. Die Parasiten des Zitterwelses. Sitzunsber. k. preuss. Akad. Wis- sensch., Berlin, 6:99-108, pi. t, 8 fig. FrOLICH, J. A. VON 1789. Beschreibungen einiger neuen Eingeweidewiirmer. Der Naturforscher, Halle, 24:101-162, pi. 4, 31 fig. 1 791. Beytrage zur Naturgeschichte der Eingeweidewiirmer. Der Natur- for«cher, Halle, 25:52-113, pi. 3, figi. 1-17. Fuhrmann, O. 1895. Die Tanien der Amphibien. Zool. Jahrb., Abt. Anat., 9:207-226, pi. 16, 19 fig. 1899. Das Genus Prosthecocotylc. Vorlaufige Mitteilung. Centrbl. Bakt. u. Parasit, (i) 25:863-867, 3 fig. 1903. L'evolution des Tcnias et en particulier de la larve de Ichthyotenias. Arch. sci. phys. nat. Geneve, (4), 16:335-337. 1903a. Idem. Bull. .soc. sci. nat, Neuchatel. 31 :386-388. 312 ILLINOIS BIOLOGICAL MONOGRAPHS C312 Gmeux, J. F. 1790. Caroli a Linne Systema naturae per regna tria naturae, se- cundum classes ordines, genera, species cum characteribus, differentiis, synonymis, locis. 1:3021-3910, (vermes). Lipsiae. GoEZE, J. A. E. 1782. Versuch einer Naturgeschichte der Eingeweidewtirmer thierischer Korper. 471 pp., 44 pH^ Blankenburg. 1800. Einige Beobachtungen iiber die Erzeugung der Eingeweidewiirumer. (/« Zeder, J. G. H. Erster Nachtrag zur Naturgeschichte der Eingeweide- wiirmer. Leipzig, pp. 317-320.) Grimm, O. A. 1872. Zur Kenntnis einiger wenig bekannten Binnenwurmer. Nachr. v. k. Gesellsch. Wissensch. u. Georg-Aug. Univ., Gottingen. 12:240-250. Grubek, a. 1878. Ein neuer Cestoden-Wirth. Zool. Anz., i :74-7S, Hall, M. C. 1910. A new species of cestode parasite (Taenia balaniceps) of the dog and of the lynx, with a note on Proteocephalus punicus. Proc. U. S. Nat. Museum, 39:i39-i5i, 9 fig- Johnston, T. H. < 1909. On a new reptilian cestode. Jour, and Proc. Roy. Soc. N. S. Wales, 43:103-116, pi. 6, fig. 1-6. 191 1. Proteocephalus Gallardi. A new cestode from the black snake. An- nals of the Queensland Museum. 10:175-182, pi. 7, fig. 1-3. 1912. A census of Australian reptilian entozoa. Proc. Roy. Soc. Queens- land, 23:233-249. 1912a. Notes on some entozoa. Proc. Roy. Soc. Queensland, 24:63-91, pi. 2-5, fig. 1-45- Jordan, D. S. and Evermann, I<. W. 1896-1900. The fishes of North and Middle America. Bull. U. S. Nat. Museum, 47, 4 pts. Kessux, K. T. 1868. [Beitrage zur zoologischen Kenntniss des Onegasee's und dessen Umgebung.] [Russian text.] (Beilage z. d. Arb. d. i. russ. naturf. Ver- samml. St. Petersburg. 183 pp., 8 pi.) Klaptocz, B. 1906. Cestoden aus Fischen, aus Varanus und Hyrax, Sitzungsber. d. k. Akad. d. Wiss., math.-naturwiss. CI. Wien, 115:121-144, i pi., 21 fig. Kraemer, a. 1892. Beitrage zur Anatomie und Histologie der Cestoden der Susswasser- fische. Zeit. wiss. Zool., 53:647-722, pi. 27-28, 42 fig. 1892a. Idem. Reprinted as dissertation, pp. 5-80, pi. 27-28, 42 fig. Leipzig. Lang, A. 1881. Untersuchungen zur vergleichenden Anatomie und Histologie des Nerven-systems der Plathelminthen. HL Mitth. zool. Stat, zu Neapel, 2:372-400, pi. 15-16, 8 fig. I© 313] PROTEOCEPHALIDAE—LA RUE 313 La Rue, G. R. 1909. On the morphology and development of a new cestode of the genus La Rue, G. R. Proteocephalus Weinland. Trans. Amer, Micros. Soc, 28:17-49, pi. 1-4, 40 fig. 1911. A revision of the cestode family Proteocephalidae. Zool. Anz., 38: 473-482. Leidv, J. 1855. Notices of some tapeworms. Proc. Acad. Nat. Sci. Phila., 7 : 443-444. 1886. On Amia and its probable Taenia. Proc. Acad. Nat. Sci. Phila., 38 .-62-63. 1887. Notice of some parasitic worms. Proc. Acad. Nat. Sci. Phila., 39 :2C- C;^ _2^ 8 fig. 1888. Parasites of the pickerel. Proc. Acad. Nat. Sci. Phila., 40:169. 1891. Notices of entozoa. Proc. Acad. Nat. Sci. Phila., 42:410-418. Leuckart, R. 1886. Die Parasiten des Menschen und die von ihnen herriirenden Krank- heiten. Ein Hand- und Lehrbuch fur Naturforscher und Aerzte. 2 Aufi., 827 pp., Leipzig & Heidelberg. Leunis, J. 1883. Synopsis der Thierkunde. 3. Auflage, i, xv + 1083 pp. Hannover. LiNSTOW, O. VON. 1875. Beobachtungen an neuen und bekannten Helminthen. Arch. f. Naturg., 41 J., 1:183-207, pi. 2-4, 32 fig. 1877. Helminthologica. Arch. f. Naturg., Berlin, 43 J., i :i-i8, pi. i, 26 fig. 1878. Compendium der Helminthologie. Ein Verzeichniss der bekannten Helminthen, (etc.). 382 pp. Hannover. 1889. Compendium der Helminthologie. Nachtrag. Die Litteratur der Jahre 1878-1889. 151 pp. Hannover. 1891. Ueber den Bau und die Entwickelung von Taenia longicollis Rud. Ein Beitrag zur Kenntniss der Fischtanien. Jena. Ztschr. f. Naturw., 25:565-576, pi. 25/ IS fig. 1903. Drei neue Tanien aus Ceylon. Centrbl. Bakt. u. Parasit. (i) Originale, 33 :532-535, '7 %• 1904. Ueber zwei neue Entozoa aus Acipenseriden. Ann. Mus. zool., Acad, imp. sci. St. Petersb., 9:17-19, 6 fig. 1904a. Neue Beobachtungen an Helminthen. (Same as above). Arch. Mikr. Anat., 69:494-496. 1906. Helminthes from the collection of the Colombo museum. Spolia Zeylanica, 3:185, 2 fig. 1908. Helminthen von Herrn Edward Jacobson in Java (Semarang) gesam- melt. Notes from the Leyden Museum, 29, note 10. Linton, E. 1889. Notes on entozoa of marine fishes of New England, with descriptions of several new species. Rep. Comr., U. S. Corn. Fish & Fisheries, (1886), _ / 14:453-51 1, 6 pi. J14 ILLINOIS BIOLOGICAL MONOGRAPHS t314 Linton, E. 1897. Notes on cestode parasites of fishes. Proc. U. S. Nat. Mus., 20:423- 456, pi. 27-34. 1901. Parasites of fishes of the Woods Hole region. Bull. U. S. Fish Com., (1899), 19:405-492, pi. 1-34, fig. 1-379. LONNBERG, £. 1889. Bidrag till Kannedomen om i Sverige forekommande Cestoder. Bi- hang K. Svenska Vetensk. Akad. Handl., 14,1-69 pp., 2 pi., 22 fig. 1894. Ueber eine neue Tetrabothriuvi Species und die Verwandtschaftsver- haltnisse der IchthyotJinien. Centrbl. Bakt. u. Parasit., 15:801-803. LUHE, M. 1898. Oochoristica nov. gen. Taeniadarum. (Vorlaufige Mitteilung). Zool. Anz., 21 :650-652. 1899. Zur Kenntnis einiger Distomen. Zool. Anz., 22:524-539. 1909. Parasitischer Plattwiirmer. II. Cestodes. Brauer's Die Susswasser- fauna Deutschlands, Heft 18. Marotel, G. 1898. Sur une teniade du Bothrops lanceolatus. (Note preliminaire.) Compt. rend. soc. biol., 50:99-101. 1899. fitude ^ologique de 1' Ichthyotaenia Calmettei Barrois. Arch. Para- sit., 2:34-42, '4 fig. Marshall, W. S. and Gilbert, N. C. 1905. Notes on the food and parasites of some fresh-water fishes from the lakes at Madison, Wis. Rep. U. S. Bur. of Fisheries, 1904:513-522. MOLIN, R. 1859. Cephalocotylea e nematoidea. Sitzungsber. k. Akad. Wissensch., math.-naturw. CI., Wien, 38:7-38, i pi., 7 fig. 1861. Prodromus faunae helminthologicae venetae adjectis disquisitionibus anatomicis et criticis. Denkschr. k. Akad. Wissensch., Wien, math.- naturw. CI., (2) 19:189-338, pi. 1-15. MONTICELLI, Fr. SaV. 1888. Contribuzione alio studio dell fauna elmintologfica del golfo Napoli. I. Richerche sullo Scolex polymorphus Rud. Mitth. zool. Stat, zu Neapel, 8:85-153. Pl. 6-7, 48 fig. 1891. Notizie su di alcune specie di Taenia. Boll. Soc. di Natural, in Napoli, (i) 5:151-174, pl. 8, 31 fig. i899. Sul Tetrabothrium Gerrardii Baird. Atti. Soc. nat. e mat. di Modena, (4) 32, 1 :9-26, pl. I, fig. 1-12. MUHLING, P. 1898. Die Helminthen-Fauna der Wirbeltiere Ostpreussens. Arch. f. Na- turg., 64 J., I :i-ii8, pl. 1-4. 28 fig. MULLER, O. F. 1780. Von Bandwurmern. Naturforscher, Halle, 14:129-203. 1782. Vom Bandwurme des Stichlings und vom milchigten Plattwurme. Naturforscher, Halle, 18:21-37, pl- 3. n fig- 1788. Zoologia Danica seu animalium Daniae et Norweg^ae rariorum ac minus notorum descriptiones et historia. 2, 56 pp., pl. 41-80. Havniae. 315] PROTEOCEPHALIDAE—LA RUE 315 NiTSCHE, H. 1909. Die Susswasserfische Deutschlands, ihre Kennzeichen, Fortpflanzung, Verbreitung und wirtschaftliche Bedeutung. Im Auftrage des Deutschen Fischereivereins gemeinfasslich kurz zusammengestellt. 4 . . . . neubearb. u. verm. Aufl. V. Berlin (D. Fischereiverein) 83 pp. NUFER, W. 1905. Die Fische des Vierwaldstattersees und ihre Parasiten. 223 pp. 4 pi., 29 fig. Luzern. OlssoNj p. 1893. Bidrag till skandinaviens helminthfauna. 2. K. Svenska Vetensk.- Akad. Hand!., 25, Art. 12, :i-4i, pi. 5, 81 fig. Pallas, P. S. 1766^ Elenchus zoophytorum sistens generum adumbrationes generaliores et specierum cognitarum succinctas descriptiones cum selectis auctorum syn- onymis. xvi + 17-28 + 451 pp. Hagae Comitum. 1781. Bemerkungen . iiber die Bandwiirmer in Menschen und Thieren. N. nord. Beytr. z. phys. u. geogr. Erd-u. Volkerbeschr. (etc.), 1:39-112, pi. 2-3, 38 fig. 181 1 -12. Fauna Asiatico-Rossica. 2 v. Petropolis. Parona, C. 1898. Elminti raccolti dal Dott. Elio Modigliani alle isole Mentawei, Engano e Sumatra. Ann. Mus. Civ. di Storia Nat. di Geneva (2), 19:102-124, pi. I, 19 fig. 1901. Di alcuni cestodi brasiliani, raccolti dal Dott. Adolfo Lutz. Boll. mus. di zool. (etc.), Genova, no. 102, pp. i-io. 1901a. Idem. Atti Soc. Ligust. sci. nat. e geogr., Genova, 11:269-276. Prenant, a. 1885. Recherches sur les vers parasites des poissons. Bull. Soc. sci. Nancy, (2) 7:206-230, pi. 1-2. Railliet, a. 1899. Sur la classification des teniades. Centrbl. Bakt. u. Parasit. (i) 26 :32-34- RAtz, S. von 1897. Beitrage zur Parasitenfauna der Balatonfische. Centrbl. Bakt. u. Parasit. (i) 22:443-453, i fig. 1900. Drei neue Cestoden aus Neu-Guinea. Vorlaufige Mitteilung. Centrbl. Bakt. u. Parasit. (i) 28:657-660. 1900a. Trois nouveaux cestodes de reptiles. Compt. rend. soc. biol., 52:980-981. Ricgenbach, E. 1895. Beitrage zur Kenntnis der Tanien der Susswasserfische. Vorlaufige Mitteilung. Centrbl. Bakt. u. Parasit., (i) 18:609-613, pi. 7, fig. 1-3. 1896. Das Genus Ichthyotaenia. Rev. Suisse de zool., 4:165-275, pi. 7-9, 44 fig. 316 ILLINOIS BIOLOGICAL MONOGRAPHS t3l6 RUDOLPHI, C. A. 1801. Beobachtungen iiber die Eingeweidewiirmer. Arch. f. Zool. u. Zoot., 2, :i-65. 1802. Fortsetzung der Beobachtungen iiber die Eingeweidewiirmer. (Con- tinuation of 1801.) Ibidem 2, .1-67, pi. i. 1802a. Idem (continued). Ibidem, 3:61-125, pi. 2. 1803. Neue Beobachtungen iiber die Eingeweidewiirmer. Arch. f. Zool. and Zoot. 3:1-32. 1808. Entozoorum sive vermium intestinalium historia naturalis. v. i, pp. xxvi 4- 527 + xxvi pp., 6 pi. Amstelaedami. 1809. Idem. V. 2 (i), 457 pp., pi. 7-12. Amstelaedami. 1810. Idem. V. 2 (2), xii -|- 386 pp. Amstelaedami. 1819. Entozoorum Synopsis cui accedunt mantissa duplex et indices locu- pletissimi. x -|- 811 pp., 3 pi. Berolini. Schneider, G. 1902. Ueber die in Fischen des finnischen Meerbusens vorkommenden Endo- parasiten. Ichthyologische Beitrage. 3. Acta Soc. pro Fauna et F'lora Fenn., 22, Art. 2, 87 pp., 2 fig. 1903. Beitrage zur Kenntnis der Helminthenfauna des finnischen Meerbu- sens. 34 pp., I pi., 10 fig. Helsingfors. 1904. Idem. Acta Soc. pro Fauna et Flora Fenn., 26, Art. 3, 34 pp., i pi., 10 fig. 1905. Die Ichthyotaenian des finnischen Meerbusens. Festschrift fur Pal- men, Helsingfors, i, Art. 8, 31 pp., i pi., 10 fig. SCHRANK, F. V. P. 1788. Verzeichniss der bisher hinlanglich bekannten Eingeweidewiirmer, nebst einer Abhandlung uber ihre Anverwandtschaften. 116 pp. Miinchen. 1803. Fauna Boica-. Durchgedachte Geschichte der in Baiem einheimschen und zahmen Thiere. 3, i Abt., 272 pp. Landshut. SCHWARZ, R. 1908. Die Ichthyotaenien der Reptilien und Beitrage zur Kenntnis der Both- riocephalen. Diss. 50 pp., 7 pi., 24 fig. Basel. Shipley, A. E. 1905. Notes on a collection of parasites belonging to the Museum of Uni- \-^rsity College, Dundee. Proc. Cambr. (Eng.) Phil. Soc, 13 :9S-i02, 2 fig. SlEBOLD, C. T. E. VON. 1835. Helminthologische Beitrage. Arch. f. Naturg., i J., i :45-84, pi. i. 1854. Ueber die Band-und Blasenwiirmer, nebst einer Einleitung iiber die Entstehung der Eingeweidewiirmer. 115. pp., 36 fig. Leipzig. Smith, A. J. 1908. Contributions to systematic helmintholog}'. Univ, Penn. Med. Bull., 20:283-294, pi. 2-10. 1908a. Idem. Reprint, pp. 37-68, pi. 2-10. 3\7] PROTEOCEPHALIDAE—LA RUE 317 Sramek, a. 1901. Helminthen der an der zoologischen Station in Podiebrad (Bohmen) untersuchten Fische. Arch. d. naturw. Landesdurchforsch. v. Bohmen, 11:94-118, fig. 50-71. Stiles, C. W. 1893. Ueber die topographische Anatomic des Gefasssystems in der Familie Taeniadae. (Bemerkungen iiber Parasiten. 17), Centrbl. Bakt. u. Parasit. 13:457-465, fig. 1-12. Stiles, C. W. and Hassall, A. 1894. A preliminary catalogue of the parasites contained in the collections of the United States Bureau of Animal Industry, United States Army Medical Museum, Biological Department of the University of Pennsylva- nia (Coll. Leidy) and in Coll. Stiles and Coll. Hassall. Vet. Mag., Phila. I :245-253, 331-354- Stossich, M. 1897. Note Parassitologiche. 10 pp., 2 pi., 17 figs. Trieste. 1898. Idem. Boll. Soc. adriat. sci. nat. in Trieste, 18:1-10, pi. 1-2, fig. 1-17. 1898a. Saggio di una fauna elmintologica di Trieste e provincie contermini. Programma della Civica Scuola R. Superiore, Trieste, 162 pp. ViBORG, E, N. 1795. Sammlung von Abhandlungen fiir Thierarzte un Oekonomen. Aus dem Danischen. i. Bandchen. 324 -j- 2 pp. Copenhagen. VoiGT, M. 1903. Beitrage zur Kenntnis des Vorkommens von Fischparasiten in den Ploner Gewassern. Forschungsber. biol. Stat, zu Plon, 10 :94-99. Wagener, G. R. 1854. Die Entwicklung der Cestoden. Nova acta Acad. nat. curios, 24, Suppl. :2i-9i, pi. 1-12. Ward, H. B. 1894. A preliminary report on the worms (mostly parasitic) collected in Lake St. Clair, in the summer of 1893. Mich. Fish Comm., Bull. 4:49-54. 1910. Internal parasites of the Sebago salmon. Bull. U. S. Bur. Fisheries, (1908) 28:1151-1194, pi. 121, 10 fig. Wedl, K. 1861. Zur Helminthenfauna Aegyptens. (2. Abt.) Sitzungsber. k. Akad. Wissensch., math. -naturw. CI., Wien, 44:463-482, 3 pi., 42 fig. Weinland, D. F. 1858. Human cestoides. x-|-e3 pp., 12 fig. Cambridge, Mass. Wright, R. R. 1879. Contributions to American Helminthology. No. i. Proc. Canad. Institute, Toronto, n. s., i :54-75, 2 pi., 23 fig. (Reprint repaged 3-23.) Zeder, J. G. H. 1800. Erster Nachtrag zur Naturgeschichte der Eingeweidewiirmer, mit Zufassen und Anmerkungen herausgegeben. xx + 320 pp., 6 pi. Leipzig. 1803. Anleitung zur Naturgeschichte der Eingeweidewiirmer. xvi + 432 pp., 4 pi. Bamberg. 318 ILLINOIS BIOLOGICAL MONOGRAPHS [318 ZSCHOKKE, F. 1884. Recherches sur I'organisation et la distribution zoologique des vers parasites des poissons d'eau douce. Arch. Biol., 5:153-241, pi. 9-10, 16 fig. (reprint repaged 1-89.) 1888. ' Recherches sur la structure anatomique et histologique des cestodes. 396 pp. 9 pi. Geneve. 1891. Die Parasitenfauna von Trutta salar. Centrbl. Bakt. u. Parasit., 10 :694-699, i pi. ; 738-745 ; 792-801 ; 829-838. 1896. Zur Faunistik der parasitischen Wiirmer von Siisswasserfischen. Centrbl. Bakt. u. Parasit., (i) 19:772-784; 815-825. 1903. Marine Schmarotzer in Siissw^asserfischen. Verhandl. naturf. Ge- sellsch. in Basel, 16:118-157, pi. i, 5 fig. 319] PROTEOCEPHALIDAE—LA RUE 319 EXPLANATION OF PLATES All original drawings, unless otherwise stated, were drawn with the aid of the camera lucida or the Edinger drawing apparatus and details have been filled in at the same magnification. Drawings are uniformly arranged with the anterior end or the dorsal surface toward the upper end of the plate unless there is a statement to the contrary. ABBREVIATIONS USED bm Basement membrane ci Cirrus cip Cirrus-pouch dj Ductus ejaculatorius def Vas deferens ef Vasa efferentia ep Epithelium exa Excretory anastomosis exd Excretory vessel, dorsal exv Excretory vessel, ventral exp Excretory pore glc Gland cells mc Circular muscles mf Muscle fibers ml Longitudinal muscles mr Muscle rhomboid ms Muscle star mtr Transverse muscles mx Muscle cross nl Lateral nerve nr Nerve ring od Oviduct oot Ootype ov Ovary ooc Oocapt rs Receptaculum seminis sh Shell gland tt Testes su Suckers sue Sucker cavity suf Sucker, fifth lit Uterus utl Lateral uterine pouches utv Ventral uterine outpocketings titp Uterine passage utvp Ventral uterine pores va Vagina vas Sphincter vaginae vi Vitellaria vid Vitelline ducts vide Vitelline duct, common 320 ILLINOIS BIOLOGICAL MONOGRAPHS [320 EXPLANATION OF PLATE Fig. ij—Proteocephalus macrocephalus (CrepHn), head, toto. Lot 71, Sebago Lake. Ward Collection. Fig. 2. — Proteocephalus pusillus Ward, head, toto, showing fifth sucker. From •Cristivomer namaycush, Lake Temagami. Fig. 3. — Proteocephalus pusillus Ward, head, toto, showing fifth sucker. From Salmo sebago, Sebago Lake. Fig. 4. — Proteocephalus pusillus Ward, head, toto, showing fifth sucker. From 'Cristivomer namaycush, Lake Temagami. Fig. 5. — Proteocephalus cernuae (Gmelin), head, toto. From lot 09.26 Ward Collection. Fig. 6. — Proteocephalus cernuae (Gmelin), head, toto. From lot 09.26 Ward Collection. Fig. 7. — Proteocephalus torulosus (Batsch), head, toto, a characteristic shape. Fig. 8. — Proteocephalus percae (Miiller), head, toto. From lot 10.122 Ward Collection. Fig. 9. — Proteocephalus percae (Muller), head, toto. From lot 10.123 Ward Collection. Fig. ID. — Ophiotaenia perspicua La Rue, head, toto. Fig. II. — Ophiotaenia calmettei (Barrois), head, toto. Fig. 12. — Crepidobothrium gerrardii (Baird), head, toto. From lot 08.472 Ward Collection. Fig. 13. — Crepidobothrium gerrardii (Baird), head, toto. From lot 10.190 Ward Collection. PLATE I 321] PROTEOCEPHALIDAE—LA RUE 321 PLATE II 322 ILLINOIS BIOLOGICAL MONOGRAPHS U22 EXPLANATION OF PLATE Fig. 14. — Proteocephalus exiguus La Rue, head, toto. Fig. 15. — Proteocephalus filicollis (Rud).=: ambiguus (Dujardin), head drawn from Schneider's in toto preparation. Fig. 16. — Proteocephalus esocis (Schneider), head, drawn from a specimen cleared in glycerine. Fig. 17. — Proteocephalus perplexus La Rue, head, toto. Fig. 18. — Proteocephalus amhloplitis (Leidy), head, toto. From material col- lected at Walnut Lake, Mich. Fig. 19. — Proteocephalus ambloplitis (Leidy), head, toto. From material col- lected at Walnut Lake, Mich. Figs. 20, 21 and 22. — Proteocephalus dubius La Rue, heads, toto, showing fifth sucker and contraction states of the suckers. Fig. 23. — Proteocephalus fallax La Rue, head, toto, showing fifth sucker. Fig. 24. — Proteocephalus singularis La Rue, head, toto. Apical prominence contracted. Fig. 25. — Proteocephalus singularis La Rue, head, toto. Apical prominence extended. Fig. 26. — Ophiotaenia filaroides La Rue, head of adult, toto. After La Rue 1909. Fig. 27. — Ophiotaenia filaroides La Rue, head of plerocercus, toto, showing vestigial fifth sucker after atrophy is well under way. After La Rue 1909, Fig. 28. — Ophiotaenia filaroides La Rue, head of plerocercus, toto, showing outline of hypertrophied fifth sucker. After La Rue 1909. Fig. 29. — Proteocephalus pmguis La Rue, head, toto, dorsal or ventral view. Fig. 30. — Proteocephalus pinguis La Rue, head, toto, dorsal or ventral view. Fig. 31. — Proteocephalus pinguis La Rue, head, toto, lateral view. Figs. 29, 30, and 31 are from lot 8, Sebago Lake. Ward Collection. Fig. 32. — Proteocephalus pinguis La Rue, head and regions of strobila, toto. From material collected at Walnut Lake, Mich. Fig. 33. — Crepidobothrium gerrardii (Baird), head, toto. After Smith 1908. Fig. 34. — Crepidobothrium gerrardii (Baird), head, toto. After Smith 1908. Figs. 35 and 36. — Proteocephalus pinguis La Rue, heads, toto, showing varia- tion in contraction states. From material collected at Walnut Lake, Mich. Fig. 37- — Ophiotaenia marenzelleri (Barrois), head, toto, after Schwarz. Fig. 38. — Ophiotaenia grandis La Rue, head, toto, showing swollen region back of head. PLATE II 323] PROTEOCEPHALIDAE — LA RUE 323 PLATE III 324 ILLINOIS BIOLOGICAL MONOGRAPHS t324 V EXPLANATION OF PLATE Fig. 39. — Proteocephalus singttlaris La Rue, head, cross-section about o.io mm. from the tip of the head, near the upper end of suckers. This section shows the beginning of the muscle cross, mx, and the heavy muscles connecting the sucker wall with the siu-face of the head. Figs. 39 and 40 are drawn to the same scale as Fig. 41. Fig. 40. — Proteocephalus singularis La Rue, head, cross-section about 0.135 mm. below tip of head and about middle of suckers. Shows heavy muscle across, mx, with some fibers reaching out to the surface of the head between the suckers. Fig. 41. — Proteocephalus singularis La Rue, head, cross-section near lower edge of suckers, showing muscle star, tus, with broadly flared ends. Nuclei are shown as the larger black spots. The closely packed groups of short heavy lines are tangentially cut ends of muscle fibers which attach to the suckers. Fig. 42. — Crepidobothrium gerrardii (Baird), vestigial fifth sucker, cross-sec- tion. Note sucker cavity and musculature. Nuclei could not be seen in this tissue. Fig. 43. — Ophiotaenia filar oides La Rue, vestigial fifth sucker, from a frontal section of a plerocercus. Note the sucker cavity filled with granules, basement membrane, nuclei and muscle fibers in and around sucker. Compare structure of vestigial sucker with that of the normal sucker beside it Fig, 44. — Ophiotaenia filaroides La Rue, vestigial fifth sucker, frontal section of head of plerocercus. Compare structures with those of Fig. 43. Scale should read 0.05 mm. Fig. 45. — Ophiotaenia filaroides La Rue, vestigial fifth sucker from a cross- section of head of a plerocercus. Note the sucker cavity filled with granules, the basement membrane, the muscles, and nuclei. Fig. 46. — Ophiotaenia filaroides La Rue, vestigial fifth sucker, cross-section of head of plerocercus. Note points mentioned for Fig. 45. Sucker cavity only partly filled with granules. Scale should read 0.05 mm. PLATE III 325] PROTEOCEPHALIDAE—LA RUE 325 PLATE IV 326 ILLINOIS BIOLOGICAL MONOGRAPHS [326 EXPLANATION OF PLATE Fig. 47. — Proteocephalus macrocephalus (Creplin), ripe proglottid showing fe- male reproductive organs. From Sebago Lake material. Fig. 48. — Proteocephalus macrocephalus (Creplin), ripe proglottid, cross-sec- tion in region of cirrus-pouch. Partial reconstruction. From Sebago Lake material. Fig. 49. — Proteocephalus macrocephalus (Creplin), ripe proglottid showing male organs. From Sebago Lake material. Fig. 50. — Proteocephalus exiguus La Rue, mature proglottid, toto. Fig. 51. — Proteocephalus exiguus La Rue, end-proglottid, ventral view of toto preparation. Note the excretory pore and the shape of the ovary. Fig. 52. — Proteocephalus exiguus La Rue, ripe proglottid, toto, as seen from dorsal side, testes omitted. Fig. 53. — Proteocephalus pusillus Ward, ripe proglottid, toto, showing uterine pouches and a rare abnormality in the position of the vagina which is here poste- rior to the cirrus-pouch. From Salmo sebago. Fig. 54. — Proteocephalus pusillus Ward, mature proglottid, toto. From Salmo sebago. Fig- 55- — Proteocephalus pusillus Ward, mature proglottid, toto, showing male reproductive organs and the usual relation of vagina and cirrus-pouch. From Cristivomer namaycush. Fig. 56. — Proteocephalus fallax La Rue, ripe proglottid, toto. Shows two ven- tral uterine pores. This figure is inverted. Fig. 57- — Proteocephalus fallax La Rue, mature proglottid, toto, ventral view. Note musculature of cirrus-pouch. PLATE IV 327] PROTEOCEPHALIDAE—LA RUE 327 PLATE V 328 ILLINOIS BIOLOGICAL MONOGRAPHS [328 EXPLANATION OF PLATE Fig. 58. — Proteocephalus filicoUis (Rud.) =ambiguus (Dujardin), whole worm. This figure and Figs. 59 and 60 were drawn from Schneider's toto preparation. Fig. 59- — Proteocephalus filicoUis (Rud.) ^ambiguus (Dujardin), mature pro- glottid, toto. Fig. 60. — Proteocephalus filicoUis (Rnd.) =ambiguus (Dujardin), ripe pro- glottid, toto. Fig. 61. — Proteocephalus esocis (Schneider), young proglottid, toto. Vagina and cirrus-pouch could not be traced to margin of proglottid. Fig. 62. — Proteocephalus esocis (Schneider), mature proglottid, toto. Fig. 63. — Proteocephalus esocis (Schneider), outline of anterior end, posterior end and middle of strobila. Fig. 64- — Proteocephalus perplexus La Rue, ripe proglottid, reconstruction showing female reproductive organs, especially lateral pouches of uterus. Fig. 65. — Proteocephalus perplexus La Rue, ripe proglottids, reconstruction showing male reproductive organs and the ovary. Note also the position of the sphincter vaginae. Figs. 64 and 65 are drawn from the same series of sections. Scale should read 0.5 mm. Fig. 66. — Proteocephalus cernuae (Gmelin), ripe proglottid, toto, showing es- pecially the uterine pouches and the slender ovarian lobes. Fig. 67. — Proteocephalus cernuae (Gmelin), mature proglottid, toto. Fig. 68. — Proteocephalus cernuae (Gmelin), old proglottid, toto. PLATE V 329] PROTEOCEPHALIDAE — LA RUE 329 PLATE VI 330 ILLINOIS BIOLOGICAL MONOGRAPHS [330 EXPLANATION OF PLATE Fig. 69. — Proteocephalus percae (Miiller), ripe proglottid, toto, ventral view. From one of Schneider's slides. Fig. 70. — Proteocephalus percae (Aliiller), ripe proglottid, toto, dorsal view. Testes omitted to show uterine pouches. From one of Schneider's slides. Fig. 71. — Proteocephalus percae (Miiller), ripe proglottid, partial reconstruc- tion from ventral sid^ showing relation of reproductive organs. From lot 10.123 Ward Collection. Fig. 72. — Proteocephalus percae (Miiller), ripe proglottid, toto. Uterine pouches omitted. From lot 10.123 Ward Collection. Fig. 73. — Proteocephalus percae (Miiller), fifth sucker, section showing struc- ture. From lot 10.122 Ward Collection. Fig. 74. — Proteocephalus percae (Miiller), ripe proglottid, partial reconstruc- tion of cross-sections to show relationship of organs in region of cirrus-pouch as seen from anterior end. From lot 10.122 Ward Collection. The letters va at the extreme right of the figure should read vas. Fig. 75. — Proteocephalus dubius La Rue, ripe proglottid, toto showing uterine pouches and shape of decadent ovary. Scale is in error, each unit equals o.i mm. Fig. 77. — Proteocephalus dubius La Rue, mature proglottid, toto. PLATE \^I^ >. 331] PROTEOCEPHALIDAE — LA RUE 331 PLATE VII 332 ILLINOIS BIOLOGICAL MONOGRAPHS [332 EXPLANATION OF PLATE Fig. 78. — Proteocephalus torulosus (Batsch), ripe proglottid, frontal section showing small part of uterus and ovary, testes covering almost the entire area between vitellaria. Fig. 79- — Proteocephalus torulosus (Batsch), ripe proglottid, frontal section showing relatively large size of ovary and the small number of uterine pouches. Fig. 80. — Proteocephalus torulosus (Batsch), ripe proglottid, cross-section in region of cirrus-pouch. Fig. 81. — Proteocephalus neglectus La Rue, ripe proglottids, toto, showing re- producti\'e organs. The cirrus-pouch is much shortened, some ducts omitted. Ventral view. Fig. 82. — Proteocephalus neglectus La Rue, cirrus-pouch and vagina, normal position and shape. Funnel-like atrium possibly a little exaggerated. Note the muscle fibers at end of cirrus-pouch. Fig. 83. — Proteocephalus singularis La Rue, ripe proglottid, frontal section showing uterine pouches and the cut parts of the much coiled excretory ducts. Fig. 84. — Proteocephalus singularis La Rue, cirrus-pouch and vagina, recon- struction. Note position of vaginal sphincter and of the dilated portion of the vagina. Fig. 85. — Proteocephalus singularis La Rue, ripe proglottid, frontal section showing arrangement of testes, vitellaria and ovary. Vagina and cirrus-pouch not shown. Fig. 86. — Proteocephalus singularis La Rue, head, frontal section showing ap- pearance and position of transverse and longitudinal muscles. Fig. 87. — Proteocephalus singularis La Rue, head, frontal section showing attachments of longitudinal muscles to the suckers. Scale should read 0.2 mm. Fig. 88. — Proteocephalus pinguis La Rue, proglottid, portion of cross-section showing relation of vagina, cirrus-pouch and excretory ducts. Fig. 89. — Proteocephalus pinguis La Rue, ventral uterine pores leading to exterior. Shown in frontal section of proglottid just below cuticula. PLATE VII ^] PROTEOCEPHALIDAE — LA RUE ' 333 PLATE VIII 334 ILLINOIS BIOLOGICAL MONOGRAPHS t334 EXPLANATION OF PLATE Fig. 90. — Proteocephalus pinguis La Rue, cirrus, vagina, \as deferens and portion of vasa efferentia. From a reconstruction. Scale should read o.i mm. Fig. 91. — Proteocephalus pinguis La Rue, complex of excretory ducts leading to the dorsal and ventral surfaces of the proglottid. Fig. 92. — Proteocephalus pinguis La Rue, ripe proglottid, toto, ventral view. From lot 8, Sebago Lake material. Fig. 93. — Proteocephalus pinguis La Rue, head, longitudinal section showing structure of suckers, etc. Fig. 94. — Monticellia coryphicephala (Monticelli), ripe proglottid, cross-section showing relations of organs to the muscle-sheath. From one of Monticelli's prep- arations. Fig. 95. — Monticellia coryphicephala (Monticelli), ripe proglottid, toto, show- ing peculiar appearance of ovary, distribution of testes over entire field between vitellaria, and the scattered vitelline follicles. From one of Monticelli's prepara- tions. Cf. Fig. 186. Fig. 96. — Monticellia coryphicephala (Monticelli), ripe proglottid, cross-section through region of ovary showing peculiar relation of organs to muscle-sheath. Note that the ovary is partly outside and partly inside this sheath. From one of Monticelli's preparations. PLATE VIII 33S] PROTEOCEPHAUDAE—LA RUE PLATE IX 336 ILLINOIS BIOLOGICAL MONOGRAPHS [336 EXPLANATION OF PLATE Fig. 97. — Ophiotaenia grandis La Rue, cirrus-pouch and vagina, cirrus partly- protruded. Fig. 98. — Ophiotaenia grandis La Rue, cirrus-pouch and vagina, cirrus partly protruded. Fig. 99. — Ophiotaenia grandis La Rue, organs of interovarial space as seen in an in toto preparation. Fig. 100. — Ophiotaenia grandis La Rue, two proglottids showing indentation at the genital pore. No genital atrium visible. Fig. loi. — Ophiotaenia grandis La Rue, mature proglottid, toto, ventral view showing reproductive organs and ventral uterine pores. Fig. 102. — Ophiotaenia perspicua La Rue, ripe proglottid, toto showing uterine pouches. Fig. 103. — Ophiotaenia filaroides La Rue, ripe proglottid, showing uterine pouches and protruded cirrus. Fig. 104. — Ophiotaenia .filaroides La Rue, organs of interovarial space from a reconstruction. After La Rue 1909. Through an error in lettering the lower part of the vagina is marked 'od' whereas the fertilization passage beneath the vagina should be marked 'od'. 'Ys* should read 'rs'. Fig. 105. — Ophiotaenia filaroides La Rue, mature proglottid, toto, unflat- tened, showing relationships of organs. After La Rue 1909. PLATE IX 337] PROTEOCEPHALIDAE — LA RUE 337 PLATE X 338 ILLINOIS BIOLOGICAL MONOGRAPHS [338 EXPLANATION OF PLATE Fig. io6. — Ophiotaenia trimeresuri (Parona), evaginated cirrus, cirrus-pouch and vagina. Note coils of ductus ejaculatorius in the swollen cirrus. Scale should read 0.3 mm. Fig. 107. — Ophiotaenia trimeresuri (Parona), cirrus-pouch and vagina, cirrus unprotruded. Note coils of ductus ejaculatorius in the cirrus-pouch. Scale should read 0.3 mm. Fig. 108. — Ophiotaenia trimeresuri (Parona), mature proglottid, toto. Uterine pouches just beginning to form. Fig. 109. — Ophiotaenia calmettei (Barrois), mature proglottid, toto. Uterine pouches more advanced than in Fig. no. Fig. no. — Ophiotaenia calmettei (Barrois), mature proglottid, toto. Begin- nings of uterine pouches may be seen. Fig. III. — Crepidobothrium gerrardii (Baird), mature proglottid, toto. From lot 10.179 Ward Collection. Fig. 112. — Crepidobothrium gerrardii (Baird), ripe proglottid, toto. From lot 08472 Ward Collection. Fig. 113. — Crepidobothrium gerrardii (Baird), nearly mature proglottid, toto. Note the great number of testes. From lot 10.190 W^ard Collection. Fig. 114. — Crepidobothrium gerrardii (Baird), mature proglottid, toto. Cirrus protruded. Drawn from slide No. 1858, Bureau of Animal Industrj\ Washington. Fig. 115. — Crepidobothrium gerrardii (Baird), mature proglottid, toto. PLATE X 339] PROTEOCBPHALIDAE — LA RUB 339 PLATE XI 340 ILLINOIS BIOLOGICAL MONOGRAPHS t340 EXPLANATION OF PLATE Fig. ii6. — Proteocephalus atnbloplitis (Leidy), head, frontal section showing vestigial fifth sucker. After Benedict. Fig. 117. — Proteocephalus atnbloplitis (Leidy), head, toto. After Benedict. Fig. 118. — Proteocephalus exiguus La Rue, ripe proglottid showing arrange- ment of organs. After Benedict. Fig. 119. — Ophiotaenia lonnbergii (Fuhrmann), head, toto. After Fuhrmann. Fig. 120. — Proteocephalus percae (Miiller), head, frontal section showing fifth sucker. After Schneider. Fig. 121. — Proteocephalus percae (Miiller), head, toto. Reproduction of Miil- ler's figure 2. Fig. 122. — Proteocephalus percae (Miiller), head, toto. Reproduction of Miil- ler's figure 3. Fig. 123. — Crepidobothrium gerrardii (Baird), head, toto. After Monticelli. Fig. 124. — Crepidobothrium gerrardii (Baird), head, toto. After Monticelli. Fig. 125. — Monticellia macrocotylea (Monticelli), head. After Monticelli. Fig. 126. — Proteocephalus pentastoma (Klaptocz), anterior face of head. After Klaptocz. Fig. 127. — Proteocephaluf pentastoma (Klaptocz), head and neck. After Klap- tocz. Fig. 128. — Proteocephalus pentastoma (Klaptocz), portion of middle of worm. After Klaptocz. Fig. 129. — Proteocephalus pentastoma (Klaptocz), posterior part of worm. After Klaptocz. Fig. 130. — Proteocephalus sulcatus (Klaptocz), head, anterior face. After Klaptocz. Fig. 131 — Proteocephalus sulcatus (Klaptocz), head. After Kloptocz. Fig. 132. — Monticellia coryphicephala (Monticelli), head, toto. Note the prom- inence of the suckers. After Monticelli. PLATE XI 341] PROTEOCEPHALIDAE—LA RUE 341 PLATE XII 342 ILLINOIS BIOLOGICAL MONOGRAPHS [342 EXPLANATION OF PLATE Fig. 133. — Proteocephalus fossatus (Riggenbach), head, toto. After Riggen- bach. Fig. 134a & b. — Proteocephalus ambloplitis (Leidy), head (a) and part of stro- bila (b). After Leidy. Fig. 135. — Proteocephalus exiguus La Rue, entire worm. After Benedict. Fig. 136. — Proteocephalus exiguus La Rue, entire worm. After Benedict. These two figures show the variation in length of neck. Fig. 137. — Proteocephalus exiguus La Rue, head, frontal section. After Bene- dict. Shows structure of the functional fifth sucker. Fig. 138. — Proteocephalus exiguus La Rue, head, toto showing fifth sucker. After Benedict. Fig. 139. — Ophiotaenia natter eri (Parona), head, toto. After Schwarz. Fig. 140. — Ophiotaenia racemosa (Rud.), head, toto. After Schwarz. Fig. 141. — Ophiotaenia trimeresuri (Parona), head, toto. After Parona. Fig. 142. — Ophiotaenia trimeresuri (Parona), head, toto. After Parona. Fig. 143. — Proteocephalus salvelini (Linton), head, toto. j\fter Linton. Fig. 144. — Proteocephalus salvelini (Linton), head. After Linton. Figs. 145, 146. — Proteocephalus torulosus (Batsch), heads, toto. After Batsch. Figs. 147, 148. — Proteocephalus dubius La Rue, heads, toto. After Zschokke. Fig. 149. — Proteocephalus dubius La Rue, proglottid. After Zschokke. Fig. iso.-^-Proteocephalus fallax La Rue, head, toto showing fifth sucker. After Kramer. Fig. 151. — Choanoscolex abscisus (Riggenbach), head, toto. After Riggenbach. Fig. 152. — Proteocephalus skorikowi (von Linstow), head, toto. After von Linstow. 137 140 3uf. 152 139 136 135 144 ^#% 1 ■■"•.'■ ;*=*?» 1^ 143 PLATE XII 343] PROTEOCEPHAUDAE — LA RUE 343 PLATE XIII 344 ILLINOIS BIOLOGICAL MONOGRAPHS [344 EXPLANATION OF PLATE Fig. 153. — Ophiotaenia punka (Cholodkovski), head, toto. After Cholod- kovski. Fig. 154. — Monticellia malopteruri (Fritsch), head, toto. After Fritsch. Fig. 155. — Ophiotaenia cahnettei (Barrois), head, toto. After Schwarz. Fig. 156. — Ophiotaenia caliiiettei (Barrois), head, toto. After Marotel. Fig. 157. — Monticellia diesingii (Monticelli), head, toto. After Monticelli. Fig. 158. — Proteocephalus agonis (Barbieri), head, toto. After Barbieri. Fig. 159. — Proteocephalus cyclops (v. Linstow), head, toto. After vx)n Linstow. Fig. 160. — Ophiotaenia pigmentata (von Linstow), head, toto. After von Linstow. Fig. 161. — Proteocephalus osculatus (Goeze), head, toto. From Cams after Wagener. This appears to be a reproduction of Goeze's figure. Fig. 162. — Proteocephalus osculatus (Goeze), young individual, toto. From Carus after Wagener. Fig. 163. — Proteocephalus osculatus (Goeze) =Taenia alternatiin transverse lineata, posterior proglottids, toto. After Goeze. Fig. 164. — Proteocephalus osculatus (Goeze) =7"a^»ia alternatini transverse lineata, head and regions of strobila. After Goeze. Fig. 165. — Proteocephalus osculatus ( Goeze) ^=Taenia alternatini transverse lineata, head, toto. After Goeze, PLATE XIII 345] PROTEOCEPHALIDAE — LA RUE 345 PLATE XIV 34^ ILLINOIS BIOLOGICAL MONOGRAPHS [346 EXPLANATION OF PLATE Fig. i66. — Proteocephalus tnalopteruri (Fritsch), ripe proglottid. Modified from Fritsch's figure. Fig. 167. — Proteocephalus longicollis (Zeder), ripe proglottid. Modified from drawing by von Linstow. Fig. 168. — Proteocephalus longicollis (Zeder), ripe proglottid, cross-section. After von Linstow. Note that the testes lie in more than one layer. Fig. 169. — Proteocephalus longicollis (Zeder), cirrus-pouch. After von Lin- stow. Fig. 170. — Proteocephalus fallax La Rue, outline of proglottids from anterior and posterior parts of strobila. After Kramer. Fig. 171. — Proteocephalus iiiacrocephalus (Creplin)=:7"a