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WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY 
 
 W. O. HOTCHKISS. Director 
 
 BULLETIN NO. 57 SCIENTIFIC SERIES NO. 12 
 
 Phytoplankton of the Inland 
 Lakes of Wisconsin 
 
 Part I 
 
 Myxophyceae, Phaeophyceae, Heterokonteae, and 
 Chlorophyceae exclusive of the Desmidiaceae. 
 
 BY 
 
 GILBERT MORGAN SMITH 
 
 MADISON, WIS. 
 
 Published by the State 
 1920 
 
Wisconsin Geological and Natural History Survey 
 
 BOARD OF COMMISSIONERS. 
 
 EMANUEL L. PHILIPP, 
 
 Governor of the State. 
 
 EDWARD A. BIRGE, President. 
 
 President of the University of Wisconsin. 
 
 President of the Wisconsin Academy of Sciences, Arts, and Letters. 
 
 CHARLES P. CARY, Vice-President. 
 
 State Superintendent of Public Instruction. 
 
 STAFF OF THE SURVEY, 1919. 
 
 /^ADMINISTRATION: 
 
 William 0. Hotchkiss, State Geologist, Director and Superintendent. 
 
 In immediate charge of Geology Division. 
 
 Ernest P. Bean, Assistant State Geologist. 
 
 Lillian M. Veerhusen, Chief Clerk. 
 
 Frances Walker, Clerk and Stenographer. 
 
 Angeline Doll, Clerk. 
 
 GEOLOGY DIVISION: 
 
 William 0. Hotchkiss, In charge. 
 
 Ernest P. Bean, Geologist, Mineral Land Classification. 
 
 T. C. Chamberlin, Consulting Geologist, Pleistocene Geology. 
 
 E. O. Ulrich, Consulting Geologist, Stratigraphy, by cooperation of the 
 U. S. G. S. 
 
 H. R. Aldrich, Geologist. 
 
 Clare Gillis, Geologist. 
 
 R. H. Whitbeck, Geographer. 
 
 T. J. Dunnewald, Field Assistant and Analyst. 
 
 P. T. Thwaites, Geologist, Well Records, Educational Rock Collection. 
 
 NATURAL HISTORY DIVISION: 
 
 Edward A. Birge, In charge. 
 
 Chancey Juday, Lake Survey. 
 
 DIVISION OF SOILS: 
 
 A. R. Whitson, In charge. 
 
 W. .1. Geib, Inspector and Editor. 
 
 M. .1. Dunnewald, Field Assistant and Analyst. 
 
 H. W. Stewart, Pheld Assistant and Physicist. 
 
557 
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 TABLE OF CONTENTS 
 
 Preface 
 
 Introduction 
 
 List of lakes investigated . . , 
 Analytical key to the genera 
 
 Myxophyceae 
 
 Phaeophyceae 
 
 Heterokonteae 
 
 Chlorophyceae 
 
 Page 
 
 1 
 
 5 
 
 J.3 
 
 21 
 
 26 
 
 65 
 
 79 
 
 88 
 
 1 300 I 6 
 
 
 
 
PREFACE 
 
 The general name plankton is given to the organisms which live iree- 
 floating in the deeper parts of lakes and ponds; the plant individuals 
 being designated the phytoplankton and the animal the zooplankton. 
 Investigations have shown that there is a very special algal flora liv- 
 ing exclusively in the plankton, in addition to the chance wanderers 
 from the littoral, or marginal, region which do not multiply when in 
 the plankton. These will be designated as the euplanktonts and tycho- 
 planktonts respectively in this work. There is still another group of 
 organisms found in lakes, namely those which thrive equally under 
 littoral or pelagic conditions. This group will be referred to as the 
 facultative planktonts. Attempts have been made to differentiate be- 
 tween organisms of these three groups by the Wests, Telling, and 
 others, although a different terminology has been used. Since the 
 question of a proper habitual classification for any particular species 
 will always be a matter of individual opinion, I have indicated at the 
 end of the description my conception of the natural habitat of the 
 organisms found in the lakes of this state. 
 
 It is only within the past twenty -five years that the phytoplankton has 
 been studied, and our knowledge of the various members constituting 
 this specialized flora has come almost exclusively from European phyco- 
 logists. William West, G. S. West and Pritsch in England; Chodat 
 and Bachmann in Switzerland ; Lemmermann, Schmidle, Schroder and 
 Volk in Germany; von Keissler, Pascher and Woloszynska in Austria- 
 Hungary; and Wesenberg-Lund in Denmark have been the chief stu- 
 dents of European phytoplankton. The central African lakes have 
 been investigated by G. S. West, Schmidle, and Woloszynska. G. S. 
 West and Playfair have studied the phytoplankton of Australia. With 
 the exception of Miss Snow’s work on Lake Erie nothing was known 
 concerning the taxonomy of North American phytoplankton at the 
 time the present work was undertaken, the pioneer work on the micros- 
 copy of the Massachussetts and Brooklyn water supplies being of little 
 value to the systematist since determinations were not carried beyond 
 the genus. 
 
 These studies of Wisconsin lakes, carried out under the auspices of 
 the Wisconsin Geological and Natural History Survey, were commenced 
 in the fall of 1913. Field work was continued during the summers of 
 
2 
 
 PREFACE 
 
 1914-15-16-17 and all lake areas of the state have been visited during 
 the progress of the investigation. Collections have been made from 
 the lakes around Madison and Oconomowoc during the entire season 
 that they are open. The June, August and early September flora of 
 the northeastern lakes is represented, while the northwestern lakes were 
 visited for two successive seasons during August. Only single collec- 
 tions were made from the northern lakes so that the data for any par- 
 ticular one of them are undoubtedly very fragmentary. 
 
 The limits of the survey are determined by the political boundaries 
 of the state and not by ecological or regional unity. There is a con- 
 tinuation of the southeastern lake group in northeastern Illinois; of 
 the northeastern lake group in the northern peninsula of Michigan ; and 
 of the northwestern lake area in Minnesota. However, variation in 
 depth and surface area together with variation in chemical content of 
 Wisconsin lakes gives a sufficient range of habitat to cover conditions 
 found in almost all other parts of the world if temperature and altitude 
 are excluded. The cosmopolitan nature of phytoplankton, therefore, 
 makes this work of value to the student of these microorganisms in 
 other sections of the United States or even other continents, and he will 
 probably find a majority of the species in any region represented in 
 the Wisconsin flora. There is a temptation to include species that have 
 not been observed in order to round out the work for the student in 
 other parts of the world. This practice has been followed in certain 
 algal floras and while it may be helpful to the general student, it causes 
 endless confusion to the phytogeographer. Only those species are in- 
 cluded in this flora which have been collected from the state. 
 
 Descriptions of plankton algae are scattered through a large number 
 of periodical publications and transactions of learned societies, many 
 with only a limited circulation, so that considerable effort has been 
 spent in giving full and correct citations for the original descriptions. 
 When subsequent descriptions have been better or have given more 
 characteristic figures references are also made to theiti. A great deal 
 of time has also been spent making camera lucida drawings since an 
 accurate figure is frequently more valuable than a description. Draw- 
 ings of the various species of a genus are generally on the same scale, 
 but there has been no attempt to draw the different genera on the same 
 scale. The finer details of cytological structure, such as the nature of 
 the chloroplast or structure of the pyrenoid, are frequently lost in pre- 
 served material ; so all of the Chlorophyceae, with the exception of the 
 Desmidiaceae, the Phaeophyceae, Heterokonteae and the Myxophyceae, 
 have been drawn from living material. 
 
 The original plan for the study of Wisconsin lake algae included those 
 attached to rocky shores or lying among the macroscopic vegetation in 
 the quieter portions of lakes in order to get the relation between the 
 
PREFACE 
 
 3 
 
 benthos and the plankton, but it soon became apparent that limitations 
 of both time and space precluded an adequate presentation of the lit- 
 toral flora; attention, therefore, has been confined to phytoplankton 
 since the second season ^s work. The great amount of material on the 
 phytoplankton has necessitated dividing the work into two portions; 
 the material included in the present volume, and the Desmidiaceae and 
 Bacillareae which are reserved for a later one. A considerable amount 
 of work has been done already on these two groups and it is hoped that 
 the complete report can be published shortly. 
 
 Phycologists are generally agreed on the broader principles of algal 
 classification but naturally differ on minor details. The classification 
 here adopted for the Myxophyceae is used almost universally. The 
 group of flagellates with brown chromatophores is frequently consid- 
 ered more animal than plant. One section, the Chrysomonadineae, 
 where there are golden brown chromatophores, seems to be sufficiently 
 related to the Phaeophyceae to warrant placing them in a description 
 of plankton algae and in the arrangement of the group I have followed 
 Pascher’s classification. Since Luther’s establishment of the Hetero- 
 konteae, the question of whether to recognize this group as a separate 
 class or a division of the Chlorophyceae has arisen. The evidence 
 seems fairly clear, however, that the origin of the group is from a 
 primitive flagellate of the Chloramoeha type and since this phylogenetic 
 starting point is so markedly different from the phylogenetic starting 
 point of the Chlorophyceae (the Polyblepharidaceae) I feel that the 
 two should be considered distinct classes. The classification used is 
 that of G. S. West, although it should be noted that he considers the 
 Heterokonteae a division of the Chlorophyceae. I have also, with a 
 few exceptions, followed West’s arrangement of the Chlorophyceae. 
 It is hoped that the keys found in this work will prove usable. They 
 are based solely upon characters of the species described herein; so 
 will be of no value for those not mentioned. 
 
 During the seasons of 1916 and 1917 the field work was assisted by a 
 grant of money from the United States Bureau of Fisheries; and the 
 extension of these studies to the lakes of northwestern Wisconsin has 
 thus been made possible. 
 
 The University of Wisconsin, 
 
 Department of Botany, 
 
 February, 1919. 
 
INTEODUCTION 
 
 Geography and geology of Wisconsin. The state of Wisconsin lies 
 between Lake Superior, Lake Michigan and the Mississippi river and 
 has an area of 56,066 square miles, cr an area somewhat larger than 
 England. Its greatest breadth is about 295 miles and greatest length 
 320 miles. Within its borders are numerous lakes, the total number 
 probably reaching well into the thousands, with an estimated surface 
 area of about 1500 square miles. They vary in size from small lakelets 
 and ponds that cover but a few acres, to Lake Winnebago with an 
 area of 215 square miles. The great majority of the lakes, however, 
 have less than a square mile of surface area. There is likewise great 
 variation in depth, but for the most part they are shallow since the 
 deepest (Green Lake) has a maximum depth of 237 feet and only a 
 few have a depth of over a hundred feet. Certain phycologists have 
 tried to differentiate between the plankton floras of ponds (heleoplank- 
 ton) and lakes (limnoplankton). The lakes of this state grade so im- 
 perceptibly from the ‘‘pond’’ to the “lake” type that it has been im- 
 possible to distinguish between the two. To set arbitrarily a surface 
 area of a square mile and depth of 25 feet as the maximal limits for a 
 pond would involve many difficulties ; since the state presents such ex- 
 amples as Beasley Lake with a surface area of 0.019 square miles and 
 a depth of 51 feet or Lake Winnebago with a surface area of 215 square 
 miles and a maximum depth of 21 feet. I have, therefore, listed all 
 bodies of water as lakes but have given, in Table 2, all available data 
 on area and depth for those desiring to recapitulate into heleoplank- 
 ton and limnoplankton. 
 
 There are, roughly speaking, three lake areas in the state ; the south- 
 eastern, northwestern and northeastern, all of which owe their origin 
 to glaciation. These lake areas are not uniformly distributed over the 
 state since the glacier invading this region was divided into lobes and 
 lakes are found in greatest abundance along the terminal and kettle 
 moraines of these various lobes. The southwestern portion of the state 
 possesses no lakes since it lies in a non-glaciated region. The south- 
 eastern lake area includes several scattered moderately sized lakes and 
 groups of smaller lakes some of which are among the deepest in the 
 state. The majority of them lie in a region of kames and pitted plains, 
 where the pits and lake basins owe their origin to the burial and sub- 
 
6 
 
 INTRODUCTION 
 
 sequent melting of large irregular blocks of ice. The Oconomowoc, 
 Lauderdale and Waupaca lake groups are of this type. A few of 
 the larger and deeper lakes, as Green and Mendota, are situated in 
 valleys eroded by preglacial streams that were possibly modified by 
 glacial action and then closed by the building of a morainal dam which 
 impounded the waters of the present lake. 
 
 The northeastern lake group lies chiefly in Vilas, Oneida and Iron 
 counties. There are hundreds of lakes in this area and their closeness 
 of position may readily be inferred from the fact that while the largest 
 of them, Trout Lake, covers only 6.5 square miles the 346 lakes and 
 ponds in Vilas county occupy 140 square miles or over 15 percent of 
 the area of a county nearly as large as Rhode Island. In few parts of 
 the world are there more lakes to the square mile. Parts of the State 
 of Minnesota, the Province of Ontario, and Finland furnish the 
 only parallel. These lakes are small, irregularly shaped, and connected 
 by streams with most irregular courses. They are all glacial in origin 
 and formed either by shallow depressions of the ground moraine, hol- 
 lows in outwash plains, or damming of recessional moraines. > The en- 
 tire region is so deeply buried by the glacial drift that no lake is due 
 to a damming of a preglacial valley. This entire region also contains 
 numerous swamps (muskegs) characteristics of a poorly drained area. 
 
 The northwestern lake area lies in Barron, Polk, Burnett, Washburn, 
 and Sawyer counties. In general it is similar to the northeastern lake 
 area in structure and origin but the lakes do not occupy so great a 
 portion of the land’s surface. It has been suggested that some of the 
 lakes in this region were formed before the last glacial invasion or Late 
 V/isconsin glacial epoch. Here we find a few lakes formed by a dam- 
 ming of preglacial valleys; Bone, Beaverdam, and Wapagossett lakes 
 for example. 
 
 The mean average temperature of Wisconsin varies from 6.6° C. in 
 the southern portion to 3.3° C. in the northern. The state has a mean 
 summer temperature similar to that of Prance, Germany, or south- 
 eastern England (14.5° to 18°) ; the average winter temperature is com- 
 parable to that of northern Sweden or central Russia (-5.4° to -8.8°). 
 All lakes in the state are frozen over during the winter, ice forming 
 during November and December and lasting until March or April in 
 the southern ones, while on some of the northern lakes ice appears in 
 October and remains until the latter part of May. The midsummer 
 surface temperature of the northern lakes is 18°-24° C. and 20°-26^ 
 in the southern lakes. 
 
 The altitude of the lakes in the northeastern part of the state varies 
 from 1550-1700 feet above sea level; in the northwestern area 1050- 
 1350 feet, and from 750 to 900 feet in the southeastern. These differ- 
 ences in elevation ai*e too slight to be of any biological significance. 
 
INTRODUCTION 
 
 7 
 
 Likewise differences in the amount of mean annual precipitation, which 
 j’ange from 28-44 inches in various parts of the state, need no discus- 
 sion since rainfall in all regions is sufficient to maintain lakes at their 
 normal level. 
 
 The underlying geological formations are, however, of prime import- 
 ance and have a marked influence on the distribution of plankton or- 
 ganisms, especially the plankton desmids. Within the state are found 
 areas of igneous, metamorphic, and sedimentary rocks each of which 
 have a different direct influence on the chemical environment of the 
 plankton organisms. The underlying rock formations of the south- 
 eastern lake area are the Niagara limestone of the Silurian; the Cin- 
 cinnati shale. Galena limestone. Lower Magnesian limestone and St. 
 Peter sandstone of the Ordovician. In the northwestern lake region 
 is found the Cambrian Potsdam sandstone, the Ordovician Lower Mag- 
 nesian limestone, together with areas of Keeweenawan trap rock and 
 Precambrian granites. The northeastern area is entirely Precambrian 
 granites. 
 
 Overlying all of these regions is a mantle of glacial drift some of 
 which is local in origin while other constituents have been transported 
 from distant regions. This ground moraine in southeastern Wisconsin 
 varies in thickness from a few feet on hill tops to over 400 feet in the 
 bottom of preglacial valleys. Mechanical analyses show that 13% con- 
 sists of crystalline rocks transported from Canada while the remaining 
 87% is local sand- and limestone. In the northeastern lake area the 
 glacial mantle varies from 75-100 feet in thickness with a maximum 
 depth of 350 feet at the southern boundary of the area. This glacial 
 accumulation is not the result of one ice invasion but of several; the 
 last, and the one which left the most material, came from the north- 
 east and transported the conspicuous sand deposits of Vilas and north- 
 ern Oneida counties from the sandstone region of northern Michigan. 
 Previous ice invasions came from the northwest and their deposits, in 
 some instances, have not been disturbed by succeeding invasions. None 
 of the drift in this region is calcareous so that all soils are acid in 
 character. The mantle of drift in the northwestern area varies from 
 500 to a few feet in thickness and is composed of material from granitic 
 and sandstone regions. There is, however, a certain amount of lime 
 in the drift at the southern limit of the lake area. 
 
 Chemical composition of the lake waters. Birge and Juday* have 
 made investigations on the chemical composition of the waters of Wis- 
 consin lakes in connection with their biochemical studies. They divide 
 the waters into three general classes; soft, medium, and hard. These 
 
 * Birge, E. A. and Juday, C. The inland lakes of Wisconsin. The dissolved 
 gases of the water and their biological significance. Bull. 22 Wis. Geol. and 
 Nat. Hist. Survey. (Sci. Ser. 7.) pp. 1-259. 1911. 
 
8 
 
 INTRODUCTION 
 
 varying degrees of hardness are due to the combination of the carbon 
 dioxide with calcium and magnesium to form carbonates, the fixed 
 (CaCOg and MgCOg) and the half-bound (CaCOg.HgCOg and 
 MgCOg.HaCOg). In neutral and acid lakes the two types of carbon 
 dioxide are present in equal amounts but in alkaline lakes there is an 
 excess of fixed carbon dioxide. This is due to the ability of the chloro- 
 phyll bearing organisms to draw upon the half-bound carbon dioxide 
 as a source of supply after the disappearance of the free carbon diox- 
 ide. The amounts of magnesium and calcium vary from lake to lake 
 and there is an almost continuous series from those having the softest 
 waters to those having the hardest. They consider those lakes whose 
 average fixed carbon dioxide does not exceed 5 cc. per liter as soft 
 water lakes, while medium waters have 6-22 cc. of carbon dioxide per 
 liter and the hard waters from 23-50 cc. per liter. The carbon dioxide 
 content varies with the depth at which the sample is taken and also 
 with the season of the year; some of the medium class lakes, for ex- 
 ample, have a sufficiently low content at times to qualify as soft water 
 lakes. All of the soft and medium waters, with the exception of Devils 
 lake in Sauk county, are located in the northeastern and northwestern 
 lake areas and many of them have sufficient free carbon dioxide to 
 give an acid reaction with phenolphthalein. The hardwater lakes are 
 all in the southeastern area and the upper stratum in them is alkaline 
 to phenolphthalein for the greater part of the year. 
 
 Aside from the question of the hardness of the water complete min- 
 eral analyses of a few lakes are also available. These results are em- 
 bodied in Table 1 and represent average conditions. They are taken 
 from the data given by Birge and Juday and their data show that 
 there is a seasonal variation and a vertical variation in the amounts of 
 certain elements present. These variations in vertical distribution are 
 well shown in their Fig. 7, p. 106 (1. c.) The lakes of southeastern 
 Wisconsin contain a rich flora of Chlorophyceae, Myxophyceae and 
 Phaeophyceae, both in quantity and quality. In the northern lake 
 areas the total volume of the plankton is, generally speaking, consider- 
 ably smaller and quite different in character. These lakes have a con- 
 siderable desmid flora in many instances, while with the exception of 
 one or two species desmids are not found in the hard waters of the 
 southeastern region. The volume of phytoplankton that can be pro- 
 duced in a lake is primarily dependent upon the available supply of 
 carbon dioxide for photosynthesis. In the northern lakes this supply 
 is chiefly the carbon dioxide dissolved in the water but in the southern 
 lakes there is in addition considerable quantities of half -bound carbon 
 dioxide which may be drawn upon after the free carbon dioxide is ex- 
 hausted. It is not surprising, therefore, that the southern lakes with 
 greater supplies of potential food materials have a greater production 
 
INTRODUCTION 
 
 9 
 
 of algae. There are certain factors modifying the growth of algae in 
 hard water lakes ; in those deep ones which become thermally stratified 
 in the summer most of the algae are restricted to the epilimnion. The 
 thickness of the epilimnion is in part dependent upon the size and shape 
 of the lake, since the wind is more effective in keeping water in circula- 
 tion on large surfaces. Algae are continually sinking to the bottom and 
 giving rise to carbon dioxide and nitrogenous products. In the deep 
 
 Table 1. — Results of mineral analyses stated in parts per million. These shoic 
 aderage content of m/nous depths and at different dates. 
 
 lakes these products of decay are chiefiy in the hypolimnion and are 
 not immediately available for reutiiization by other algae. In shal- 
 low lakes without thermal stratification these products are immediately 
 available for the vegetative activities of algae. Shallow lakes, there- 
 fore, support proportionally larger algal floras. The restriction of 
 the desmids to the soft water lakes was first pointed out by the Wests 
 and their observations have been confirmed in Wisconsin (Birge and 
 Juday, 1. c. p. 138). An examination of the chemical analyses of such 
 soft water lakes as Devils, Trout and Kawaguesaga (Table 1) shows 
 that in these lakes which contain numerous desmids the calcium and 
 magnesium content is relatively small. The influence of calcium and 
 magnesium on the distribution of desmids may be that of a direct in- 
 hibition of growth or the absence of these elements may permit an 
 acid condition which is favorable for the growth of desmids. Data on 
 organic matter and distribution of nitrogen in lakes of the state are 
 lacking. The scarcity or abundance of available nitrogen is doubtless 
 an important factor in the volume of algae produced in a lake, and it 
 is a well known fact that as regions become more thickly settled and 
 drainage entering the lake becomes richer in nitrogenous material the 
 growth of plankton algae becomes more luxuriant. 
 
10 
 
 INTRODUCTION 
 
 Methods of collection and study. All plankton collections have been 
 made with nets. In general both the bolting silk net and the cotton 
 disc net were used. The bolting silk net of No. 20 bolting cloth (new 
 No. 25) is that described by Juday*. The cotton disc net is made by 
 attaching a filter designed for purifying drinking water (Jones Mod- 
 ern Filter made by the Jones Mfg. Co., Boston, Mass.) to the bottom 
 of an eighteen inch cone of canvas whose mouth is held open by a light 
 metal ring ten inches in diameter. In using this filter a special cot- 
 ton disc supplied by the manufacturer is placed in the filter and the 
 whole apparatus drawn through the water. The algae collect on the 
 disc and when there is a sufficient accumulation the disc is taken from 
 the filter and shaken in a bottle with a small amount of water which 
 removes the algae. This net catches many of the smaller organisms 
 that pass through the bolting silk (the nannoplankton) and it is also 
 very useful in obtaining samples by dipping when no boat is available. 
 Whenever possible samples have been gathered by towing the nets at 
 the surface and all collections have been made in the deep parts of all 
 lakes to avoid, as far as possible, the littoral flora. No attempt has 
 been made to study the vertical distribution of the algae in any lake. 
 
 In studying the flora of any region a field laboratory was established 
 and with that as a center excursions were made to the surrounding 
 lakes. By traveling from lake to lake in an automobile collections 
 could be made in the morning and the material studied the same after- 
 noon and the following day. In the northeastern lake area where 
 there are no roads in many cases, but where lakes are close together, 
 they can be visited by portaging a canoe from lake to lake. Collections 
 have been made from row boats, where they were obtainable, but in a 
 few instances collections had to be made by repeatedly dipping the 
 net after wading to where the water was 3-4 feet deep or from rafts. 
 Upon returning to the temporary laboratory equipped with compound 
 microscope, camera lueida, and drawing materials, the living specimens 
 were studied and numerous pencil camera lueida drawings made of all 
 doubtful, interesting, or rare organisms, together with notes on occur- 
 rence and ocular micrometer measurements of known forms. No ob- 
 servations were made on desmids or diatoms at this time. The study 
 of the Chlorophyceae, Myxophyceae and Phaeophyceae in the living 
 condition is particularly important since many of them do not preserve 
 well and certain features such as cilia, chloroplasts, and contractile 
 vacuoles are lost when material is preserved. All drawings of one 
 species are mounted on the same sheet and corresponding notes on an- 
 other. The.se ai-e then filed in species and genus covers in the usual 
 
 * Juday, C. Limnological apparatus. Trans. Wis. Acad. Sci. Arts & Lett. 
 18 ^: 566 - 592 . 1916 . 
 
INTRODUCTION 
 
 11 
 
 manner for herbarium specimens so that all data on any particular spe- 
 cies are immediately accessible. The figures for the plates of this work 
 have been redrawn from camera lucida sketches made in field labora- 
 tories. The confined space of a vial is not favorable for algae and the 
 more delicate forms, as Uglenopsis, frequently go to pieces after stand- 
 ing a few hours. It is impossible to have the vials uncorked while 
 transporting them from station to station but they should be opened 
 immediately on return to field headquarters. I have also found it 
 helpful to keep them as cool as possible and have stored them in hotel 
 refrigerators until ready to make observations. Formalin has proven 
 a satisfactory means of preserving the desmids and diatoms until their 
 study can be taken up during the winter months. 
 
 The following list of simple reagents is helpful in studying the vari- 
 ous structures of living algae. Cilia of motile forms are more easily 
 seen when the cells have been rendered immobile by mounting in a 1% 
 cocaine solution. Mounting in a dilute aqueous acid fuchsin also helps. 
 Pyrenoids can be recognized by the grouping of the starch grains when 
 the latter have been stained with iodine. It is difficult to strain pyre- 
 Roids of living cells. Gelatinous envelopes are best demonstrated by 
 Errera's method of mounting in dilute India ink which gives the col- 
 orless envelope the appearance of a halo around the cells in contrast 
 to the dark background of water containing the ink. Nuclei can be 
 demonstrated by Strasburger ’s solution of methyl green in 1% acetic 
 acid. Simple microchemical tests are Sudan III for fats, iodine for 
 starch, zinc chloriodide for cellulose, and Euthineum Red for pectin. 
 
 Lakes studied. The following table gives a list of lakes in the state 
 from which plankton samples have been taken. All known hydro- 
 graphic maps, morphometric data, general descriptions of many lakes 
 and general maps of the various lake areas have been given by Birge 
 and Juday^' so that any one wishing further data concerning a particu- 
 lar lake is referred to their work. They have not, however, mapped or 
 discussed many of the smaller lakes of the northern regions. Since 
 most of the lakes in the state were named by the settlers of the region 
 considerable poverty of vocabulary is noticed and Round, Mud, Devils, 
 Long, and Sand are repeated many times. In other instances Indian 
 (Chippewa) names have been retained as the white man settled the 
 region. In these also there is a certain amount of duplication and 
 Sishebogema (lake with many bays) or Pokegama (side or branch lake) 
 may be cited as examples. It is too bad that these names have not been 
 retained to a greater extent, but certain of the English names like 
 Razorback, Crawling Stone, Lost Canoe, Tenderfoot or Fishtrap are not 
 
 * Birge, E. A. and Juday, C. The inland lakes of Wisconsin. Bull. 27: Wis. 
 Geol. & Nat. Hist. Survey. (Sci. Ser. 9). pp. 1-137. 1914. 
 
12 
 
 INTRODUCTION ^ 
 
 without interest. This is not the place, however, for the legends on 
 the origin of these peculiar names nor for a discussion of the occurrence 
 of several French names in the list. In order to avoid misunder- 
 standing the town and range in which the lake occurs is given. When 
 more than one lake with the same name has been visited, a serial num- 
 ber has been added and both the lake name and serial number are used 
 in giving stations for the various algae. 
 
INTRODUCTION 
 
 13 
 
 Table 2. — 'Table giving available data on location and size of lakes visited during the 
 course of this investigation. 'The first column refers to the page on which a mop 
 of the lake may be found in Birge and Juday, The inland lakes of Wisconsin, the 
 hydrography and morphometry. Bull. 27. Wis. Geol. and Nat. Hist. Survey. 
 
 Papre 
 
 map- 
 
 ped 
 
 Lake 
 
 County 
 
 Town 
 
 Ranffe 
 
 Lenffth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 
 Adelaide 
 
 Vilas 
 
 43N 
 
 5E 
 
 1 .47 
 
 .32 
 
 68.9 
 
 45 . 0 
 
 
 
 Rusk 
 
 34 N 
 
 1 
 
 8W i 
 
 1.06 
 
 .30 
 
 
 
 1?0 
 
 
 Polk 
 
 34N 
 
 1 
 
 17W 
 
 3.00 
 
 l.OO 
 
 18.0 
 
 1,785.6 
 
 
 Bass 0) 
 
 Vilas 
 
 40N 
 
 HE 
 
 .50 
 
 .24 
 
 
 Bass (2) 
 
 Vilas 
 
 42N 
 
 GE 
 
 .93 
 
 irr. 
 
 
 
 
 
 
 40N 
 
 14W 
 
 
 
 
 
 
 Bear (1) 
 
 
 34N 
 
 14W 
 
 .45 
 
 .40 
 
 
 
 
 Bear (2) 
 
 Polk 
 
 33N 
 
 17W 
 
 .88 
 
 .59 
 
 
 
 120 
 
 Bear (3) ■. 
 
 
 36N 
 
 12W 
 
 4.50 
 
 1.00 
 
 
 
 
 
 Washburn. 
 
 
 
 
 
 
 
 
 Bear Trap 
 
 Polk 
 
 .33N 
 
 17W 
 
 1.05 
 
 .48 
 
 
 
 104 
 
 Beasley 
 
 Waupaca .... 
 
 21N 
 
 HE 
 
 .25 
 
 .10 
 
 51.2 
 
 13.5 
 
 
 Beavei* (1) 
 
 Vilas 
 
 44N 
 
 5E 
 
 ,44 
 
 • 25 
 
 40 
 
 Beaver (2) 
 
 Waukesha ... 
 
 8N 
 
 18E 
 
 MO 
 
 .44 
 
 49.0 
 
 305.4 
 
 120 
 
 Beaverdam 
 
 Barron 
 
 33N 
 
 14W 
 
 3.80 
 
 .75 
 
 91.9 
 
 1,267.2 
 
 
 
 
 36N 
 
 13W 
 
 
 
 
 
 Bettine 
 
 Vilas 
 
 43N 
 
 7E 
 
 .75 
 
 .56 
 
 
 
 120 
 
 Biff 
 
 Polk 
 
 32N 
 
 18W 
 
 .80 
 
 .65 
 
 
 
 
 
 
 33N 
 
 
 
 
 
 120 
 
 Biff Butternut 
 
 Polk 
 
 36N 
 
 17W 
 
 1.20 
 
 .60 
 
 21.3 
 
 384.0 
 
 120 
 
 Biff McKenzie 
 
 • Burnett 
 
 40N 
 
 14W 
 
 2.25 
 
 1.05 
 
 116 
 
 Biff St, Germain 
 
 Vilas 
 
 40N 
 
 8E 
 
 2.62 
 
 1.25 
 
 
 
 118 
 
 Birch (1) 
 
 Vilas 
 
 43N 
 
 5E 
 
 1.50 
 
 .74 
 
 
 
 120 
 
 Birch (2) 
 
 Washburn .. . 
 
 37N 
 
 low 
 
 .90 
 
 .70 
 
 57.4 
 
 243.2 
 
 120 
 
 Birch Island 
 
 Burnett 
 
 40N 
 
 14W 
 
 2.10 
 
 irr. 
 
 
 
 
 Blake 
 
 Polk 
 
 35N 
 
 16W 
 
 1.90 
 
 irr. 
 
 
 
 
 Bloom 
 
 Burnett 
 
 37N 
 
 18W 
 
 
 
 
 
 
 Blue Gill 
 
 Vilas 
 
 43N 
 
 7E 
 
 .12 
 
 .09 
 
 
 
 120 
 
 Bone 
 
 Polk 
 
 35N 
 
 16W 
 
 4.80 
 
 1.00 
 
 49.2 
 
 2,054.4 
 
 
 
 
 36N 
 
 
 118 
 
 Boulder 
 
 Vilas 
 
 42N 
 
 7E 
 
 2.25 
 
 1.20 
 
 19.7 
 
 614.4 
 
 74 
 
 Browns 
 
 Racine 
 
 2N 
 
 19E 
 
 1.25 
 
 .75 
 
 23.0 
 
 390.4 
 
 
 
 
 3N 
 
 
 
 Bullhead 
 
 Vilas 
 
 4CN 
 
 6E 
 
 .31 
 
 .26 
 
 
 
 IZ 
 
 Camp 
 
 Kenosha 
 
 IN 
 
 20E 
 
 1.50 
 
 1.00 
 
 19.7 
 
 256.0 
 
 
 Canteen 
 
 Vilas 
 
 43N 
 
 7E 
 
 .31 
 
 .17 
 
 116 
 
 Carroll 
 
 Vilas 
 
 SON 
 
 7E 
 
 1.30 
 
 .47 
 
 23.0 
 
 288.0 
 
 
 
 
 40N 
 
 
 
 
 Carson (see Flora) 
 
 
 
 
 
 
 
 
14 
 
 INTRODUCTION 
 
 Table 2. — (Continued) 
 
 Pa^e 
 
 map- 
 
 p<'.d 
 
 Lake 
 
 County 
 
 Town 
 
 Range 
 
 Length 
 V Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 116 
 
 
 Vilas 
 
 SON 
 
 lOE 
 
 2.87 
 
 irr. 
 
 19.7 
 
 902.4 
 
 
 
 40N 
 
 HE 
 
 
 
 
 
 116 
 
 
 Vilas 
 
 38N 
 
 6E 
 
 2.25 
 
 Avv. 
 
 27.9 
 
 008. 0 
 
 75 
 
 
 
 IN 
 
 20E 
 
 .72 
 
 .3") 
 
 
 
 
 Polk 
 
 35N 
 
 13W 
 
 
 
 
 
 
 
 
 37N 
 
 
 
 
 
 
 120 
 
 
 
 38N 
 
 9W 
 
 6.40 
 
 1.10 
 
 
 
 120 
 
 
 
 33N 
 
 low 
 
 3.25 
 
 irr. 
 
 
 
 120 
 
 
 
 38N 
 
 low 
 
 3.84 
 
 1.92 
 
 
 
 
 
 39N 
 
 
 
 
 
 
 
 
 Polk 
 
 35N 
 
 IGW 
 
 . ^5 
 
 .3G 
 
 
 
 116 
 
 
 Oneida 
 
 SON 
 
 7E 
 
 2.10 
 
 irr. 
 
 82.0 
 
 921.6 
 
 116 
 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.40 
 
 1.12 
 
 32.8 
 
 672.0 
 
 
 
 43N 
 
 8E 
 
 .69 
 
 .36 
 
 
 
 116 
 
 Crab 
 
 Vilas 
 
 43N 
 
 6E 
 
 2.12 
 
 1.35 
 
 44.3 
 
 1,318.4 
 
 116 
 
 Cranberry 
 
 Vilas 
 
 40N 
 
 HE 
 
 1.25 
 
 .70 
 
 11.5 
 
 332.8 
 
 116 
 
 Crawl in» Stone 
 
 Vilas 
 
 40N 
 
 5E 
 
 2.40 
 
 1.65 
 
 93.0 
 
 1,600.0 
 
 
 Rnrnet.t 
 
 38N 
 
 16W 
 
 1.44 
 
 .44 
 
 
 
 II 
 
 P.n rlis 
 
 Oneida 
 
 SON 
 
 6E 
 
 .76 
 
 .25 
 
 
 
 120 
 
 DpAr 
 
 Polk 
 
 S4N 
 
 17W 
 
 2.80 
 
 .70 
 
 39.4 
 
 806.4 
 
 
 
 
 18W 
 
 
 
 
 
 70 
 
 Delavan 
 
 Walworth 
 
 2N 
 
 16E 
 
 3.75 
 
 1.10 
 
 56.7 
 
 1,813.2 
 
 
 J')p< Mninp.s 
 
 Itnrnett 
 
 41N 
 
 14 W 
 
 1.00 
 
 .30 
 
 
 
 30, 32 
 
 Devils (1) 
 
 Pauk 
 
 IIN 
 
 6E 
 
 1.25 
 
 .61 
 
 43.2 
 
 360.8 
 
 120 
 
 J vj 1 
 
 Ua iTon 
 
 36N 
 
 HW 
 
 1.60 
 
 .40 
 
 
 
 J i ] s 
 
 Vilas 
 
 4SN 
 
 8E 
 
 .44 
 
 .26 
 
 
 
 
 nininrmd 
 
 Polk 
 
 37N 
 
 17W 
 
 .60 
 
 .60 
 
 
 
 120 
 
 ' I'inpk . 
 
 Ba.rvnn 
 
 SON 
 
 13W 
 
 .50 
 
 .30 
 
 
 
 
 
 Rn.rT'on 
 
 86N 
 
 13W 
 
 .60 
 
 .25 
 
 
 
 
 J>nTihflnn 
 
 Bn I'tiplt 
 
 38N 
 
 17W 
 
 
 
 
 
 
 ma nn 
 
 Rn iTief t 
 
 38N 
 
 17W 
 
 
 
 
 
 74 
 
 Eaffle 
 
 Kacine 
 
 SN 
 
 20E 
 
 1.31 
 
 1.00 
 
 13.1 
 
 486.4 
 
 120 
 
 ‘Fla.'it. 
 
 Polk 
 
 33N 
 
 18W 
 
 .74 
 
 .52 
 
 
 
 75 
 
 Elizabeth 
 
 Kenosha 
 
 IN 
 
 19E 
 
 2.62 
 
 .87 
 
 26.2 
 
 800.0 
 
 116 
 
 Eenp.e 
 
 Vilas 
 
 40N 
 
 5E 
 
 3.25 
 
 2.10 
 
 93.0 
 
 3,492.0 
 
 120 
 
 Fish 
 
 Burnett 
 
 40N 
 
 14W 
 
 1.30 
 
 .55 
 
 
 
 116 
 
 Fishtrap 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.50 
 
 .62 
 
 29.5 
 
 326.4 
 
 116 
 
 Flora 
 
 Vilas 
 
 43N 
 
 7E 
 
 1.31 
 
 irr. 
 
 
 
 Listed as Clear Lake by Birtre and Juday. 
 
INTRODVCTIOIi 
 
 15 
 
 Table 2 (Continued) 
 
 Page 
 
 map- 
 
 ped 
 
 Lake 
 
 County 
 
 Town 
 
 Range 
 
 Length 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 116 
 
 Found 
 
 Vilas 
 
 inxT 
 
 8E 
 
 1.06 
 
 .69 
 
 
 
 52 
 
 Fowler 
 
 Waukesha ... 
 
 8N 
 
 17E 
 
 .94 
 
 .44 
 
 50.0 
 
 W 83.5 
 
 66 
 
 Geneva 
 
 Walworth 
 
 IN 
 
 16E 
 
 7.50 
 
 2.00 
 
 142.0 
 
 5,451.3 
 
 
 
 
 2N 
 
 17E 
 
 
 
 
 
 
 George 
 
 Vilas 
 
 44N 
 
 5E 
 
 .56 
 
 .33 
 
 
 
 120 
 
 Granite 
 
 Barron 
 
 36N 
 
 13W 
 
 1.60 
 
 .30 
 
 
 
 
 Grassy 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.31 
 
 .64 
 
 
 
 92 
 
 Green (1) 
 
 Green Lake. . 
 
 15N 
 
 12E 
 
 7.40 
 
 2.00 
 
 237.0 
 
 7,342.4 
 
 
 
 
 16N 
 
 1.SE 
 
 
 
 
 
 76 
 
 Green (2) 
 
 Walworth 
 
 4N 
 
 16E 
 
 1.09 
 
 .66 
 
 56.8 
 
 277.9 
 
 120 
 
 Grindstone 
 
 Sawyer 
 
 40N 
 
 8W 
 
 3.40 
 
 2.10 
 
 47.6 
 
 3,462.4 
 
 120 
 
 Half Moon 
 
 Polk 
 
 35N 
 
 9W 
 
 17W 
 
 1.77 
 
 .50 
 
 116 
 
 Harris 
 
 Vilas 
 
 44N 
 
 5E 
 
 1.51 
 
 irr. 
 
 
 
 
 Helen (1) 
 
 Vilas 
 
 40N 
 
 HE 
 
 .58 
 
 .14 
 
 
 
 
 Helen (2) 
 
 Vilas 
 
 44N 
 
 5E 
 
 .47 
 
 .20 
 
 
 
 116 
 
 High 
 
 Vilas 
 
 42N 
 
 7E 
 
 2.00 
 
 1.00 
 
 31.2 
 
 761.6 
 
 
 
 
 43N 
 
 8E 
 
 
 
 
 Hill 
 
 Oneida 
 
 39N 
 
 6E 
 
 .18 
 
 .14 
 
 
 
 
 Hillman 
 
 Barron 
 
 34N 
 
 14W 
 
 .60 
 
 .25 
 
 
 
 75 
 
 Hooker 
 
 Kcnosiha. 
 
 IN 
 
 20E 
 
 .75 
 
 .37 
 
 23.0 
 
 64.0 
 
 120 
 
 Horse 
 
 Polk 
 
 33N 
 
 18W 
 
 1.22 
 
 .40 
 
 120 
 
 Horseshoe® (1 ) 
 
 Polk 
 
 34N 
 
 15W 
 
 2. .50 
 
 1.00 
 
 59.0 
 
 800.0 
 
 120 
 
 Horseshoe (2) 
 
 Polk 
 
 33N 
 
 17W 
 
 .80 
 
 .62 
 
 
 Howey 
 
 Polk 
 
 34N 
 
 17W 
 
 .25 
 
 .20 
 
 
 
 120 
 
 Island 
 
 Busk 
 
 33N 
 
 8W 
 
 1.75 
 
 .65 
 
 47.6 
 
 435.2 
 
 118 
 
 Jag 
 
 Vilas 
 
 42N 
 
 6E 
 
 1.00 
 
 irr. 
 
 
 
 Jennie 
 
 Vilas 
 
 43N 
 
 6E 
 
 .44 
 
 .34 
 
 
 
 
 Jones 
 
 Vilas 
 
 43N 
 
 8E 
 
 .58 
 
 .21 
 
 
 
 116 
 
 Kawaguesaga 
 
 Oneida 
 
 39N 
 
 6E 
 
 4.25 
 
 irr. 
 
 55.8 
 
 2067 . 2 
 
 26 
 
 Kegonsa 
 
 T)a,ne 
 
 6N 
 
 7E 
 
 lOE 
 
 3.00 
 
 2.25 
 
 31.4 
 
 3,145.2 
 
 
 
 
 
 HE 
 
 
 
 
 Kimball 
 
 Washburn . . . 
 
 42N 
 
 13W 
 
 1.68 
 
 .80 
 
 
 
 
 Kitten 
 
 Vilas 
 
 43N 
 
 7E 
 
 .34 
 
 .19 
 
 
 
 120 
 
 Lac Court Oreilles.. . 
 
 Sawyer 
 
 39N 
 
 8W 
 
 5.65 
 
 1.90 
 
 67.2 
 
 5 248.0 
 
 
 
 
 40N 
 
 9W 
 
 
 
 
 
 116 
 
 Lac du Flambeau 
 
 Vilas 
 
 40N 
 
 4E 
 
 2.00 
 
 irr. 
 
 49.2 
 
 1,280,0 
 
 
 
 
 
 5E 
 
 
 
 
 
 52 
 
 Lac la Belle 
 
 Waukesha ... 
 
 8N 
 
 17E 
 
 2.70 
 
 1.12 
 
 46.4 
 
 1,137.5 
 
 116 
 
 Laura 
 
 Vilas 
 
 41N 
 
 8E 
 
 1.50 
 
 .90 
 
 39.4 
 
 640.0 
 
 
 Lake of the Woods. . 
 
 Burnett 
 
 38N 
 
 17W 
 
 
 
 
 
 ’ Listed as Big: Horseshoe by Birge and Juday. 
 
16 
 
 INTRODUCTION 
 
 Table 2 — (Continued) 
 
 Page 
 
 map- 
 
 ped 
 
 Lake 
 
 County 
 
 Townj 
 
 Range 
 
 Length 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 
 Lily 
 
 
 41N 
 
 14W 
 
 
 
 
 
 
 Lindy 
 
 Burnett 
 
 40N 
 
 14W 
 
 
 
 
 
 
 Little Bass (1) 
 
 Vilas 
 
 42N 
 
 6E 
 
 .28 
 
 .19 
 
 
 
 
 
 Polk 
 
 34N 
 
 17 W' 
 
 
 
 
 
 
 Little Bear 
 
 Vilas 
 
 43N 
 
 6E 
 
 .69 
 
 .44 
 
 
 
 
 
 Polk 
 
 36N 
 
 17W 
 
 .60 
 
 .35 
 
 
 
 
 Little Crooked 
 
 Vilas 
 
 42N 
 
 6E 
 
 1.06 
 
 irr. 
 
 
 
 
 
 
 38N 
 
 17W 
 
 ,45 
 
 .30 
 
 
 
 
 T.ittle Rice (1) 
 
 
 33N 
 
 8W 
 
 .70 
 
 .40 
 
 
 
 118 
 
 Little Rice (2i 
 
 Vilas 
 
 42N 
 
 7E 
 
 .76 
 
 .38 
 
 
 
 120 
 
 
 
 38N 
 
 18W 
 
 .82 
 
 .48 
 
 
 
 T.rmg n 1 
 
 Burnett 
 
 41N 
 
 14W 
 
 1.85 
 
 .35 
 
 
 
 120 
 
 Long (2)., 
 
 Polk 
 
 34N 
 
 17W 
 
 1.70 
 
 .55 
 
 24.6 
 
 384.0 
 
 
 liOng CSl 
 
 Vilas 
 
 40N 
 
 1 5E 
 
 1.40 
 
 .60 
 
 55.8 
 
 448.0 
 
 104 
 
 Long (4) 
 
 Waupaca . . . . 
 
 21N 
 
 HE 
 
 .94 
 
 .36 
 
 77.7 
 
 108.4 
 
 
 TiOmi 
 
 Barron 
 
 34N 
 
 1 14W 
 
 1.00 
 
 .45 
 
 
 
 116 
 
 T .osjt', 
 
 Vilas 
 
 40N 
 
 8E 
 
 1.69 
 
 .86 
 
 
 
 118 
 
 T.nst Canoe 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.25 
 
 .38 
 
 41.0 
 
 204.8 
 
 120 
 
 T,r>veless 
 
 Polk 
 
 34N 
 
 17W 
 
 1.09 
 
 .32 
 
 21.3 
 
 153.6 
 
 T.ynv 
 
 Vilas 
 
 43N 
 
 i 7E 
 
 .75 
 
 .66 
 
 
 
 
 1 
 
 1 
 
 ! Vilas 
 
 44N 
 
 I r>E 
 
 .37 
 
 .19 
 
 
 
 104 
 
 Marion j 
 
 Marl ! 
 
 Waupaca 
 
 21N 
 
 HE 
 
 .51 
 
 .19 
 
 60.6 
 
 21.3 
 
 75 
 
 Mary 
 
 Kenosha 
 
 IN 
 
 19E 
 
 1.20 
 
 .70 
 
 26.2 
 
 275.2 
 
 12 
 
 Mendota 1 
 
 1 Dane. 
 
 7N 
 
 9E 
 
 5.90 
 
 4.60 
 
 84.0 
 
 9,729.8 
 
 
 
 8N 
 
 
 
 
 
 
 
 Mercer 
 
 Oneida 
 
 39N 
 
 5E 
 
 1.30 
 
 .69 
 
 
 
 
 Mernnt . . 
 
 j Rnrnet.t 
 
 40N 
 
 14W 
 
 
 
 
 
 
 i M etfl 
 
 Vilas 
 
 40N 
 
 HE 
 
 .64 
 
 .26 
 
 
 
 76 
 
 Middle 
 
 Walworth. . . . 
 
 4N 
 
 16E 
 
 1.60 
 
 .45 
 
 50.0 
 
 284.0 
 
 120 
 
 Middle McKenzie ® . . 
 
 Rn rnet.t. 
 
 40N 
 
 14W 
 
 1.10 
 
 .90 
 
 
 
 78 
 
 Mill 
 
 Walworth — 
 
 • 4N 
 
 16E 
 
 .75 
 
 .49 
 
 50.0 
 
 296.4 
 
 20 
 
 Monona 
 
 Dane 
 
 7N 
 
 9E 
 
 4.16 
 
 2.40 
 
 74.0 
 
 3,482.7 
 
 
 
 
 lOE 
 
 
 
 
 
 
 Mild (11 . . . 
 
 Polk 
 
 34N 
 
 17W 
 
 .66 
 
 .28 
 
 
 
 
 Mnd (21 
 
 Vilas 
 
 40N 
 
 5E 
 
 .81 
 
 .56 
 
 
 
 114 
 
 Mud (8) 
 
 Vilas 
 
 .89N 
 
 7E 
 
 .87 
 
 .36 
 
 
 
 * Listed as McKenzie lakes. 
 
INTRODUCTION 
 
 17 
 
 Table 2 — (Continued) 
 
 
 1 
 
 1 
 
 1 Lake 
 
 County 
 
 1 
 
 ! Town 
 
 1 
 
 Rang’e 
 
 Length 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 104 
 
 Mud (4) 
 
 Waupaca 
 
 21N 
 
 HE 
 
 .13 
 
 .06 
 
 32.0 
 
 i 
 
 i 9.7 
 
 
 
 
 38N 
 
 17 W 
 
 1.68 
 
 1.10 
 
 
 i 
 
 116 
 
 
 Vilas 
 
 41N 
 
 7E 
 
 i 1.93 
 
 irr . 
 
 
 1 
 
 1 
 
 ^20 
 
 
 
 42N 
 
 13W 
 
 1 2.00 
 
 1.25 
 
 
 
 54 
 
 Naerawicka 
 
 Waukesha .. . 
 
 7N 
 
 18E 
 
 I 2.75 
 
 1.12 
 
 94.4 
 
 917.6 
 
 54 
 
 Nashotah (Upper).. . 
 
 Waukesha .. . 
 
 7N 
 
 17E 
 
 .81 
 
 .40 
 
 57.2 
 
 1.36.7 
 
 54 
 
 Nashotah (Lower) . . 
 
 Waukesha .. . 
 
 7N 
 
 17E 
 
 .79 
 
 .25 
 
 46.2 
 
 100.3 
 
 
 Nell 
 
 Vilas 
 
 44N 
 
 5E 
 
 1 .46 
 
 .15 
 
 
 
 54 
 
 Nemahbin (Upper).. 
 
 Waukesha .. . 
 
 7N 
 
 17E 
 
 1.05 
 
 .56 
 
 62.0 
 
 271.1 
 
 54 
 
 Nemahbin (Lower). . 
 
 Waukesha .. . 
 
 7N 
 
 17E 
 
 .93 
 
 .60 
 
 35.2 
 
 265.5 
 
 
 
 
 41N 
 
 14W 
 
 
 
 
 
 116 
 
 
 Vilas 
 
 44N 
 
 5E 
 
 1.00 
 
 .69 
 
 
 
 
 North Twin 
 
 Polk 
 
 33N 
 
 16W 
 
 .92 
 
 .30 
 
 
 
 
 Number One 
 
 Sawyer 
 
 37N 
 
 9W' 
 
 .25 
 
 .18 
 
 
 
 
 Oak 
 
 Burnett 
 
 40N 
 
 14W 
 
 .70 
 
 • 45 
 
 
 
 46 
 
 Oconomowoc 
 
 Waukesha. . . 
 
 7N 
 
 17E 
 
 1.75 
 
 .83 
 
 62.6 
 
 631.3 
 
 46 
 
 Okauchee 
 
 Waukesha. . . 
 
 8N 
 
 17E 
 
 2.37 
 
 1.80 
 
 94.0 
 
 1,0.57.0 
 
 
 
 
 
 18E 
 
 
 
 
 
 
 Old Taylors 
 
 Waupaca .... 
 
 22N 
 
 HE 
 
 
 
 
 
 104 
 
 Otter 
 
 Waupaca 
 
 22N 
 
 HE 
 
 .40 
 
 .08 
 
 40.0 
 
 14.5 
 
 120 
 
 Owen 
 
 Bavfield .... 
 
 44N 
 
 7W 
 
 6.25 
 
 irr. 
 
 88.6 
 
 2.032.0 
 
 
 
 
 43N 
 
 75 
 
 Paddock 
 
 Keno.sha, 
 
 IN 
 
 20E 
 
 .62 
 
 .37 
 
 31.0 
 
 9.5 
 
 116 
 
 Palmer 
 
 Vilas 
 
 43N 
 
 8E 
 
 1.75 
 
 1.25 
 
 14.8 
 
 614.4 
 
 116 
 
 Pardee 
 
 Vilas 
 
 44N 
 
 4E 
 
 .94 1 
 
 .87 
 
 63 
 
 Pewaukee 
 
 Waukesha .. . 
 
 7N 
 
 18E 
 
 4.50 
 
 1.20 
 
 45.0 
 
 2,298.0 
 
 
 
 
 
 19E 
 
 
 
 
 
 
 Pike 
 
 Polk 
 
 33N 
 
 16W 
 
 1.18 
 
 .30 
 
 
 
 40 
 
 Pine (1) 
 
 Waukesha... . 
 
 8N 
 
 18E 
 
 2.30 
 
 1.05 
 
 90.0 
 
 755.7 
 
 
 Pine (2) 
 
 Polk 
 
 33N 
 
 17W^ 
 
 .66 
 
 .28 
 
 
 
 
 Pine Tree 
 
 Polk 
 
 32N 
 
 16W 
 
 .92 
 
 irr. 
 
 
 
 116 
 
 Plum 
 
 Vilas 
 
 41N 
 
 7E 
 
 4.20 
 
 1.25 
 
 50.8 
 
 1,088.0 
 
 
 
 
 8E 
 
 120 
 
 Pokegrama (1) 
 
 Washburn 
 
 42N 
 
 12W 
 
 2.40 
 
 .60 
 
 23.0 
 
 505.6 
 
 116 
 
 Pokegrama (2) 
 
 Vilas 
 
 40N 
 
 5E 
 
 3.25 
 
 1.90 
 
 42.6 
 
 1,216.0 
 
 
 
 
 41N 
 
 
 
 
 
 
 120 
 
 Poke^ama (3) 
 
 Barron 
 
 33N 
 
 low 
 
 3.50 
 
 .70 
 
 
 
 
 Poor Farm 
 
 Polk 
 
 33N 
 
 ICW' 
 
 
 
 
 104 
 
 Pope 
 
 Wa.npac.Ji .... 
 
 21N 
 
 HE 
 
 .22 
 
 .11 
 
 40.6 
 
 16.2 
 
 120 
 
 Poplar 
 
 Polk 
 
 33N 
 
 18W 
 
 .72 
 
 .38 
 
 9 
 
18 
 
 INTRODUCTION 
 
 Tablb 2. — (Continued) 
 
 Page 
 
 map- 
 
 ped 
 
 Lake 
 
 County 
 
 Town 
 
 Range 
 
 Length 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 8 
 
 Poygan 
 
 Waushara ... 
 
 19N 
 
 13E 
 
 7.70 
 
 3.50 
 
 10.8 
 
 10,992.2 
 
 120 
 
 Prairie 
 
 
 33N 
 
 IIW 
 
 6.50 
 
 .70 
 
 
 
 
 
 
 34N 
 
 
 
 
 
 
 104 
 
 Rainbow (1) 
 
 
 22N 
 
 HE 
 
 .62 
 
 .55 
 
 95.1 
 
 137.5 
 
 116 
 
 Rainbow (2) 
 
 Vilas 
 
 44N 
 
 5E 
 
 .63 
 
 .44 
 
 
 
 116 
 
 Razorback 
 
 Vilas 
 
 41N 
 
 8E 
 
 1.10 
 
 .90 
 
 31.1 
 
 352.0 
 
 
 Red Bass 
 
 Vilas 
 
 43N 
 
 7E 
 
 .40 
 
 .13 
 
 
 
 
 Reserve 
 
 
 39N 
 
 8W 
 
 1.00 
 
 .55 
 
 
 
 
 Rice (1) 
 
 
 35N 
 
 IIW 
 
 2.75 
 
 .60 
 
 
 
 
 Rice (2) 
 
 Vilas 
 
 42N 
 
 6E 
 
 .45 
 
 .30 
 
 
 
 
 Rock 
 
 Vilas 
 
 44N 
 
 5E 
 
 1.12 
 
 .37 
 
 
 
 
 Roonev 
 
 
 40N 
 
 14 W 
 
 
 
 
 
 
 Rose 
 
 Vilas 
 
 40N 
 
 7E 
 
 1.14 
 
 .25 
 
 
 
 
 Round O) 
 
 Vilas 
 
 43N 
 
 6E 
 
 .62 
 
 .40 
 
 
 
 
 Round (2) 
 
 Polk 
 
 33N 
 
 18W 
 
 .58 
 
 .41 
 
 
 
 
 Round (3) 
 
 Polk 
 
 32N 
 
 17W 
 
 .26 
 
 .20 
 
 
 
 104 
 
 Round (4) 
 
 Waupaca 
 
 22N 
 
 HE 
 
 .55 
 
 .35 
 
 66.6 
 
 106.2 
 
 
 Rozen 
 
 Vilas 
 
 40N 
 
 7E 
 
 .68 
 
 .50 
 
 
 
 116 
 
 Rudolnh 
 
 Vilas 
 
 43N 
 
 7E 
 
 .52 
 
 .22 
 
 
 
 120 
 
 St. Croix 
 
 Douglas 
 
 45N 
 
 IIW 
 
 4.00 
 
 .55 
 
 19.7 
 
 1,030.4 
 
 
 
 
 
 12W 
 
 
 
 
 
 Sand (1) 
 
 Burnett, 
 
 38N 
 
 16W 
 
 
 
 
 
 120 
 
 Sand (2) 
 
 Burnett 
 
 40N 
 
 15W 
 
 1.70 
 
 1.45 
 
 
 
 120 
 
 Sand (3) 
 
 Polk 
 
 33N 
 
 18W 
 
 1.22 
 
 .45 
 
 
 
 116 
 
 Sand< (4) 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.65 
 
 .87 
 
 67.2 
 
 793.6 
 
 
 Sanford 
 
 Vilas 
 
 43N 
 
 6E 
 
 .77 
 
 .40 
 
 
 
 120 
 
 Shell 
 
 Washburn. . . 
 
 37N 
 
 12W 
 
 3.25 
 
 2.50 
 
 49.2 
 
 3,200.0 
 
 
 
 
 38N 
 
 13W 
 
 
 
 
 
 120 
 
 Silver HI 
 
 Ba.rron 
 
 36N 
 
 13W 
 
 
 
 
 
 75 
 
 Silver (2) 
 
 Kenosha 
 
 IN 
 
 20E 
 
 1.25 
 
 .87 
 
 42.6 
 
 582.0 
 
 58 
 
 Silver (3) 
 
 Waukesha... . 
 
 7N 
 
 17E 
 
 .97 
 
 .56 
 
 44.0 
 
 231.9 
 
 
 Sishebocema 
 
 Vilas 
 
 39N 
 
 5E 
 
 2.50 
 
 irr. 
 
 
 
 
 
 
 40N 
 
 
 
 
 
 
 58 
 
 Soft 
 
 Waukesha... . 
 
 7N 
 
 17E 
 
 .32 
 
 .20 
 
 
 
 Speese 
 
 Oneida 
 
 39N 
 
 5E 
 
 .32 
 
 .31 
 
 
 
 116 
 
 SQuirrel 
 
 Oneida. 
 
 39N 
 
 5E 
 
 3.75 
 
 1.00 
 
 33.8 
 
 1,568.0 
 
 
 Sonl.h Crab 
 
 Vilas 
 
 43N 
 
 6E 
 
 .68 
 
 .20 
 
 
 
 120 
 
 Spirit 
 
 Burnett 
 
 37N 
 
 18W 
 
 1.70 
 
 1.00 
 
 24.6 
 
 640.0 
 
 116 
 
 Star 
 
 Vilas 
 
 41N 
 
 8E 
 
 2.12 
 
 1.60 
 
 26.2 
 
 1,152.0 
 
 * Listed as White Sand Lake by Birg-e and Juday. 
 
INTRODUCTION 
 
 19 
 
 Table 2 --(Continued) 
 
 Page 
 
 map- 
 
 ped 
 
 Lake 
 
 County 
 
 Town 
 
 Range 
 
 Length 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 breadth 
 
 (Miles) 
 
 Maxi- 
 
 mum 
 
 depth 
 
 (Feet) 
 
 Area 
 
 (Acres) 
 
 
 
 Vilas 
 
 42N 
 
 6E 
 
 .44 
 
 .28 
 
 
 
 
 
 
 39N 
 
 5E 
 
 . 75 
 
 .37 
 
 
 
 
 
 Vilas 
 
 4SN 
 
 5E 
 
 .56 
 
 .40 
 
 
 
 
 Tank 
 
 
 ON 
 
 6E 
 
 .24 
 
 .08 
 
 
 
 104 
 
 
 
 22N 
 
 HE 
 
 .45 
 
 .31 
 
 55.7 
 
 51.2 
 
 116 
 
 
 
 43N 
 
 8E 
 
 1.60 
 
 1.50 
 
 27.9 
 
 646.4 
 
 
 Tied Canoe ® 
 
 
 
 
 
 Travis 
 
 Polk 
 
 33N 
 
 17W 
 
 
 
 
 
 116 
 
 Trout 
 
 Vilas 
 
 41N 
 
 6E 
 
 4.50 
 
 2.40 
 
 115.0 
 
 4,160.0 
 
 
 
 
 42N 
 
 7E 
 
 
 
 116 
 
 Turtle (North) 
 
 Vilas 
 
 43N 
 
 5E 
 
 1.25 
 
 .80 
 
 47.6 
 
 640.0 
 
 116 
 
 Turtle (South) 
 
 Vilas 
 
 43N 
 
 5E 
 
 2.25 
 
 .63 
 
 43.0 
 
 793.6 
 
 120 
 
 Turtle (Lower) 
 
 Barron 
 
 34N 
 
 14W 
 
 1.50 
 
 .45 
 
 
 
 120 
 
 Turtle (Upper) 
 
 Barron 
 
 34N 
 
 14W 
 
 2.30 
 
 .40 
 
 23.0 
 
 480.0 
 
 120 
 
 Vermilion 
 
 Barron 
 
 3f)N 
 
 13W 
 
 1.70 
 
 1.20 
 
 
 120 
 
 WapagossetU 
 
 Polk 
 
 33N 
 
 ICW 
 
 3.50 
 
 1.20 
 
 27.9 
 
 1,452.8 
 
 
 
 
 
 17W 
 
 
 
 
 
 24 
 
 Waubesa 
 
 Dane 
 
 6N 
 
 lOE 
 
 4.20 
 
 1.40 
 
 36.6 
 
 2,034.4 
 
 
 
 
 7N 
 
 
 
 
 White Ash 
 
 Polk 
 
 34N 
 
 low 
 
 1.77 
 
 .40 
 
 
 
 120 
 
 Whitefish 
 
 Sa.wypr 
 
 39N 
 
 9W 
 
 2.60 
 
 . 65 
 
 73.8 
 
 896.0 
 
 116 
 
 White Sand 
 
 Vilas 
 
 41N 
 
 5E 
 
 2.75 
 
 1.00 
 
 
 
 Whitney 
 
 Vila.s 
 
 42N 
 
 6E 
 
 .56 
 
 .45 
 
 
 
 116 
 
 Wildcat 
 
 Vilas 
 
 43N 
 
 7E 
 
 .87 
 
 .60 
 
 
 
 120 
 
 Wild Goose 
 
 Polk 
 
 34N 
 
 17W 
 
 .95 
 
 .64 
 
 14.8 
 
 256.0 
 
 92 
 
 Winnebago 
 
 
 15N 
 
 17E 
 
 28.00 
 
 10.40 
 
 21.0 
 
 137,708.0 
 
 
 
 
 20N 
 
 
 
 
 116 
 
 Wolf 
 
 Vilas 
 
 42N 
 
 7E 
 
 1.21 
 
 .84 
 
 
 
 104 
 
 Youngs 
 
 Waupaca 
 
 21N 
 
 HE 
 
 .09 
 
 .07 
 
 11.6 
 
 3.0 
 
 ®See Lost Canoe. 
 
 •Listed as Sucker Lake by Birge and Juday. 
 
KEY TO THE GENEEA BASED UPON THE 
 VEGETATIVE CHAKACTERS. 
 
 1. (35) Celoring matter not restricted to definite plastids 
 
 Class Myxophyceae 
 
 2. (22) Cells solitary or in colonies, never in filaments 
 
 Order Coccogoneales 
 
 3. (12) Cells solitary or in colonies that never contain more than 
 
 a few cells 
 
 4. ( 7) Cells spherical or hemispherical 
 
 5. ( 6) Cells without a definite arrangement Chroococcus p. 
 
 6. ( 5) Cells in a flat plate Merismopedia p. 
 
 7. ( 4) Cells longer than they are broad 
 
 8. (11) Individual cells not enclosed by a special gelatinous vesicle 
 
 9. (10) Ends of cells rounded Rhabdoderma p. 
 
 10. ( 9) Ends of cells pointed Dactylococcopsis p. 
 
 11. ( 8) Individual cells or groups of cells enclosed by a gelatinous 
 
 vesicle Gloeothece p. 
 
 12. ( 3) Cells in colonies that contain many cells when mature 
 
 13. ( 18) Cellular arrangement within colony definite 
 
 14. ( 15) Cells forming a flat plate Merismopedia p. 
 
 15. ( 14) Cells forming a hollow sphere one cell in thickness 
 
 16. ( 17) Center of colony with radiating gelatinous strands 
 
 Gomphosphaeria p. 
 
 17. ( 16) Center of colony without radiating gelatinous strands 
 
 Coelosphaerium p. 
 
 18. ( 21) Cells spherical 
 
 1’9. ( 20) Cells densely aggregated Microcystis p. 
 
 20. ( 19) Cells some distance from one another Aphanocapsa p. 
 
 21. ( 18) Cells longer than they are broad Aphanothece p. 
 
 22. ( 2) Cells in simple or branched filaments. .Order Hormogoneales 
 
 23. ( 30) Trichomes without heterocysts Family Oscillatoriaceae 
 
 24. ( 29) Trichomes solitary or in flocculent readily dissociating 
 
 masses 
 
 25. ( 26) Trichomes containing but one spirally twisted cell 
 
 Spirulina p. 
 
 26. ( 25) Trichomes containing more than one cell 
 
 27. ( 28) Sheaths of filament firm, generally projecting beyond the 
 
 trichome Lyngbya p. 
 
 28. ( 27) Sheath delicate or lacking, not projecting beyond the tri- 
 
 chome Osclllatorla p. 
 
 29. ( 24) Trichomes laterally united to form free-floating bundles 
 
 which do not dissociate readily Trichodesmium p. 
 
 30. ( 23) Trichomes with heterocysts 
 
 2 
 
 3 
 
 4 
 
 5 
 
 27 
 
 31 
 
 8 
 
 9 
 
 46 
 
 47 
 
 15 
 
 13 
 
 14 
 
 31 
 
 16 
 
 36 
 
 33 
 
 19 
 
 38 
 
 41 
 
 43 
 
 23 
 
 24 
 
 25 
 
 ,49 
 
 27 
 
 . 52 
 
 .50 
 
 ,54 
 
 31 
 
22 
 
 WISCONSIN PHYTOPLANKTON 
 
 31. ( 34) Trichomes not attenuated Family Nostocaceae 32 
 
 32. ( 33) Filaments solitary or interwoven to form flocculent masses 
 
 of small size Anabaena 
 
 33. ( 32) Filaments laterally joined to form small plate-like colonies 
 
 of macroscopic size Aphanizomenon 
 
 Trichomes attenuated to a hair-like point Gloeotrichia 
 
 Coloring matter in definite chromatophores 
 
 Chromoplasts golden brown in color 
 
 Wall heavily impregnated with silica and definitely marked 
 
 with grooves or rows of dots Bacillarieae (see part 2). 
 
 Wall not heavily impregnated with silica 
 
 Class Phaeophyceae 
 
 Cells generally motile, rarely forming palmella or rhizopo- 
 
 dial stages Division Euchrysomonadinae 
 
 Cells with one flagellum Order Chromulinales 
 
 Cells naked Chrysamoeba 
 
 Cells with a differentiated periplast 
 
 Family Mallomonadaceae 
 
 Cells solitary Mallomonas 
 
 Cells in colonies Chrysosphaerella 
 
 Cells with two flagella 
 
 Flagella of equal length Synura 
 
 Flagella of unequal length Order Ochromonadales 
 
 Cells in a definite receptacle Family Dinobryaceae 
 
 Receptacles homogeneous, without growth rings. .Dinobryon 
 
 Receptacles with successive growth rings Hyalobryon 
 
 Cells never in a definite receptacle Uroglenopsis 
 
 ( 39) Cells usually immobile, rarely motile 
 
 ( 54) Cells spherical to ovoid, embedded in a gelatinous mass 
 
 Phaeococcus 
 
 54. ( 53) Cells with pseudopodial processes 
 
 Division Rhlzochrysidinae 
 
 Cells solitary or in irregular colonies Rhizochrysis 
 
 Cells in a linear series Chrysidastrum 
 
 Chromoplast grass-green or yellowish-green in color 
 
 Chromoplast yellowish-green, with oil not starch the assimi- 
 lation product Class Heterokonteae 
 
 Vegetative cells motile Chlorochromonas 
 
 Vegetative cells immobile 
 
 Cells solitary or in colonies, never in filaments 
 
 Order Heterococcales 
 
 Cells epiphytic Peroniella 
 
 Cells free-floating 
 
 Length of cells several times the diameter Ophiocytium 
 
 Length of cells less than twice the diameter 
 
 Cells irregularly distributed throughout an ovoid, gelatinous 
 envelope Chlorobotrys 
 
 67. ( C6) Cells arranged about a common center and enclosed by an 
 
 irregular, gelatinous envelope Botryococcus 
 
 68. ( 61) Cells united to form simple filaments Tribonema 
 
 69. ( 58) Chloroplast grass-green, generally with pyrenoids and starch 
 
 Class Chlorophyceae 70 
 
 34. 
 
 35. 
 
 36. 
 
 37. 
 
 38. 
 
 39. 
 
 40. 
 
 41. 
 
 42. 
 
 43. 
 
 44. 
 
 45. 
 
 46. 
 
 47. 
 
 48. 
 
 49. 
 
 50. 
 
 51. 
 
 52. 
 
 53. 
 
 55. 
 
 56. 
 
 57. 
 
 58. 
 
 59. 
 
 60. 
 61. 
 
 62. 
 
 63. 
 
 64. 
 
 65. 
 
 66 . 
 
 ( 31) 
 ( 1 ) 
 ( 57) 
 ( 38) 
 
 ( 37) 
 
 ( 52) 
 
 ( 45) 
 ( 42) 
 ( 41) 
 
 ( 44) 
 ( 43) 
 ( 40) 
 ( 47) 
 
 ( 46) 
 ( 51) 
 ( 50) 
 
 ( 49) 
 ( 48) 
 9) 
 
 ( 56) 
 ( 55) 
 ( 36) 
 ( 69) 
 
 ( 60) 
 ( 59) 
 { 68 ) 
 
 ( 63) 
 ( 62) 
 ( 65) 
 ( 64) 
 ( 67) 
 
 p. 55 
 
 p. 61 
 
 p. 63 
 
 36 
 
 37 
 
 39 
 
 40 
 
 41 
 p. 67 
 
 43 
 p. 67 
 p. 69 
 46 
 p. 70 
 
 48 
 
 49 
 p. 72 
 p. 75 
 p. 71 
 
 53 
 
 p. 76 
 
 55 
 p. 77 
 p. 78 
 
 58 
 
 59 
 
 p. 80 
 61 
 
 62 
 p. 81 
 
 64 
 
 p. 85 
 66 
 
 p. 82 
 
 p. 33 
 p. 87 
 
70. 
 
 ( 71) 
 
 71. 
 
 ( 70) 
 
 72. 
 
 ( 85) 
 
 73. 
 
 ( 84) 
 
 74. 
 
 ( 75) 
 
 75. 
 
 ( 74) 
 
 76. 
 
 ( 77) 
 
 77. 
 
 ( 76) 
 
 78. 
 
 ( 79) 
 
 79. 
 
 ( 78) 
 
 80. 
 
 ( 83) 
 
 81. 
 
 ( 82) 
 
 82. 
 
 ( 81) 
 
 83. 
 
 ( 80) 
 
 84. 
 
 ( 73) 
 
 85. 
 
 ( 72) 
 
 86. 
 
 (183) 
 
 87. 
 
 (122) 
 
 88. 
 
 (121) 
 
 89. 
 
 ( 92) 
 
 90. 
 
 ( 91) 
 
 81. 
 
 ( 90) 
 
 92. 
 
 ( 89) 
 
 93. 
 
 (116) 
 
 94. 
 
 (109:) 
 
 95. 
 
 (102) 
 
 96. 
 
 ( 99) 
 
 ■97. 
 
 ( 98) 
 
 98. 
 
 ( 97) 
 
 99. 
 
 ( 96) 
 
 100. 
 
 (101) 
 
 101. 
 
 (100) 
 
 102. 
 
 ( 95) 
 
 103. 
 
 (108) 
 
 104. 
 
 (107) 
 
 105. 
 
 (106) 
 
 106. 
 
 (105) 
 
 107. 
 
 (104) 
 
 108. 
 
 (103) 
 
 109. 
 
 ( 94) 
 
 110. 
 
 (111) 
 
 111. 
 
 (110) 
 
 112. 
 
 (113) 
 
 113. 
 
 (112) 
 
 WISCONSIN PHYTOPLANKTON 
 
 23 
 
 Cells solitary or in families, divided into two symmetrical 
 halves with a chloroplast in each half. Median region 
 generally constricted . . Family Desmidiaceae (See Part 2 ) 
 Cells not divided into two symmetrical halves and without 
 
 median constrictions 
 
 Cilia normally present in vegetative cells. .Order Volvocales 
 
 Anterior end of cells with two cilia 
 
 Cells solitary Chlamydomonas 
 
 Cells in colonies Family Volvocaceae 
 
 Colony a flat plate Gonium 
 
 Colony a hollow sphere 
 
 Cells mutually compressed Pandorina 
 
 Cells some distance from one another 
 
 Colony with not more than 256 cells 
 
 Asexual reproduction by division of all cells to form daugh- 
 ter colonies Eudorina 
 
 Asexual reproduction by division of certain cells to form 
 
 daughter colonies Pleodorina 
 
 Colony generally containing many cells Volvox 
 
 Anterior end of cells with four cilia Carteria 
 
 Cilia not present in vegetative cells 
 
 Cells solitary or in colonies, never in simple or branched 
 
 filaments Order Protococcales 
 
 Cells solitary 
 
 Cells free-floating 
 
 Cell shape angular 
 
 Angles simple or with spines, never with long setae 
 
 Tetraedron 
 
 Angles with tufts of long setae Polyedriopsis 
 
 Cells spherical, ovoid, or elongate 
 
 Length of cells not more than three times the diameter. . . . 
 
 Cells spherical 
 
 Cell w^all smooth 
 
 Cells embedded in a gelatinous sheath 
 
 Gelatinous sheath lamellated Gloeocystis 
 
 Gelatinous sheath not lamellated Planktosphaeria 
 
 Cells not embedded in a gelatinous sheath 
 
 Wall lamellated Gloeotaenium 
 
 Wall not lamellated Chlorella 
 
 Wall sculptured, denticulate, or with long spines or setae.. 
 
 Setae or long spines covering the wall 
 
 Wall with setae 
 
 Setae the same thickness throughout, or gradually' taper- 
 ing Golenkinia 
 
 Setae visibly thickened in the lower third. . Acanthosphaeria 
 
 Walls with long spines Echinosphaerella 
 
 Denticulations or ridges covering the walls Trochiscia 
 
 Cells ovoid to reniform 
 
 Cells reniform Nephrocytium 
 
 Cells ovoid 
 
 Walls without setae or spines Oocystis 
 
 Walls with spines or setae 
 
 72 
 
 73 
 
 74 
 p. 90 
 
 76 
 p. 94 
 78 
 p. 95 
 80 
 81 
 
 p. 95 
 
 p. 96 
 p. 97 
 p. 92 
 86 
 
 87 
 
 88 
 
 89 
 
 90 
 
 p. 115 
 p. 124 
 
 93 
 
 94 
 
 95 
 
 96 
 
 97 
 
 p. 100 
 
 p. 103 
 100 
 p. 115 
 
 p. 108 
 
 103 
 
 104 
 
 105 
 
 p. 127 
 
 p. 128 
 p. 128 
 108 
 110 
 p. 114 
 112 
 p. 110 
 
 114 
 
24 WISCONSIN PHYTOPLANKTON 
 
 114. (116) Setae somewhat tapering Lagerheimia p. 
 
 115. (114) Setae not tapering Franceia p. 
 
 116. ( 93) LfCngth of cells several times the diameter 
 
 117. (118) Ends of cells produced into setae Schroederia p. 
 
 118. (117) Ends of cells not produced into setae 
 
 119. (120) Chloroplast with an axial row of pyrenoids Closteriopsis p. 
 
 120. (119) Chloroplast without or with one pyrenoid. . Ankistrodesmus p. 
 
 121. ( 88) Cells epiphytic or epizootic Characium p. 
 
 122. ( 87) Cells in colonies 
 
 123. (142) Colonies enclosed by a conspicuous gelatinous sheath 
 
 124. (125) Cells connected by branching remains of old cell walls 
 
 Dictyosphaerium p. 
 
 125. (124) Cells not connected by branching remains of old cell walls. . 
 
 126. (137) Cells spherical to ovoid or reniform 
 
 127. (136) Chloroplast cup to disc-shaped and parietal 
 
 128. (129) Cells with pseudocilia Tetraspora p. 
 
 129. (128) Cells without pseudocilia - 
 
 130. (131) Colonies never containing more than eight cells. .Gloeocystis p. 
 
 131. (130) Colonies always with at least eight cells 
 
 132. (133) Cells ovoid to reniform Gloeocystopsis p. 
 
 j 33. (132) Cells spherical 
 
 134. (136) Chloroplasts of old cells cup-shaped.. Sphaerocystis p. 
 
 io5. (134) Chloroplasts of old cells disciform Planktosphaeria p. 
 
 136. (127) Chloroplasts star-shaped and central Asterococcus p. 
 
 1S7. (126) Cells elongate 
 
 138. (141) Cells straight 
 
 139. (140) Colonies with cells in groups of two Elaktothrix p. 
 
 140. (139) Colonies with cells in groups of 2-4-8 Quadrigula p. 
 
 141. (138) Cells curved Kirchneriella p. 
 
 112. (123) Cells not enclosed by a gelatinous sheath 
 
 148. (156) Colonies always forming a flat plate 
 
 144. (155) Number of cells, except in rare cases, greater than two 
 
 145. (152) Cells quadrately arranged 
 
 146. (147) Quadrate arrangement apparent in end view of colony 
 
 Tetradesmus p. 
 
 147. (146) Quadrate arrangement apparent in front view of colony 
 
 148. (149) Cells without setae or spines Crucigenia p. 
 
 149. (148) Cells with spines or setae 
 
 150. (151) Long setae or spines on outer face of cells. . . .Micractinium p. 
 
 151. (150) Short spines on outer face of cells Tetrastrum p. 
 
 152. (145) Cells not quadrately arranged 
 
 153. (154) Colony a fiat circular or oval disc Pediastrum p. 
 
 154. (153) Colony a single or double row of cells Scenedesmus p. 
 
 155. (144) Number of cells in colony always two Euastropsis p. 
 
 156. (143) Colony not forming a flat plate 
 
 157. (166) Colony enclosed by old cell wall 
 
 158. (165) Wall enclosing colony greatly expanded and homogeneous.. 
 
 159. (162) Wall with spines or setae 
 
 160. (161) Setae somewhat tapering Lagerheimia p. 
 
 161. (160) Setae not tapering Franceia p. 
 
 162. (159) Wall without spines or setae 
 
 163. (164) Cells ovoid Obcystis p. 
 
 129 
 
 ,131 
 
 117 
 
 136 
 
 119 
 
 ,136 
 
 ,134 
 
 175 
 
 123 
 
 124 
 
 , 104 
 
 126 
 
 127 
 
 128 
 
 102 
 
 130 
 
 100 
 
 132 
 
 102 
 
 134 
 
 101 
 
 103 
 
 103 
 
 138 
 
 139 
 
 139 
 
 137 
 
 140 
 
 143 
 
 144 
 
 145 
 
 146 
 
 150 
 
 148 
 
 144 
 
 150 
 
 125 
 
 149 
 
 153 
 
 166 
 
 150 
 
 174 
 
 157 
 
 168 
 
 159 
 
 160 
 
 129 
 
 131 
 
 163 
 
 110 
 
WISCONSIN PHYTOPLANKTON 
 
 25 
 
 184. (163) Cells ovoid to reniform Nephrocytium p. 114 
 
 165. (158) Wall lamellated but not expanded Gloeotaenium p. 115 
 
 166. (157) Colony not enclosed by old cell wall 167 
 
 167. (176) Length of cell not more than twice the breadth 168 
 
 168. (171) Remains of old cell walls at center of and holding colony 
 
 together 169 
 
 169. (170) Cells spherical Westella p. 106 
 
 170. (169) Cells ovoid to reniform Dimorphococcus p. 106 
 
 171. (168) Colonies without remains of old cell wall at center 172 
 
 172. (173) Outer face of cells with long setae Micractinium p. 125 
 
 173. (172) Outer face of cells with short spines or without ornamenta- 
 
 tion 174 
 
 174. (175) Cells without spines on outer face Coelastrum p. 160 
 
 175. (174) Cells with short spines on outer face Sorastrum p. 162 
 
 176. (167) Length of cells several times the breadth 177 
 
 177. (178) Colony forming a closed hollow sac Hydrodictyon p. 165 
 
 178. (177) Colony not forming a closed hollow sac 179 
 
 179. (180) Cells radiating from a common center Actinastrum p. 164 
 
 380. (179) Cells not radiating from a common center 181 
 
 381. (182) Cells straight or arcuate Ankistrodesmus p. 134 
 
 182. (181) Cells markedly curved Selenastrum p. 132 
 
 183. ( 86) Cells in simple or branched filaments 184 
 
 184. (195) Cells with one to eight chloroplasts, chloroplasts never re- 
 
 ticulate 185 
 
 185. (192) Chloroplasts parietal 186 
 
 186. (191) Chloroplasts laminate to disciform 187 
 
 187. (188) Cells in simple filaments Ulothrix p. 179 
 
 188. (187) Cells in branching filaments 189 
 
 18'9. (190) Setae confined to terminal cells or lacking. .. Stigeoclonium p. 180 
 
 190. (189) Setae occurring on any cell of filament Aphanochaete p. 181 
 
 191. (186) Chloroplast a spiral band Spirogyra p. 185 
 
 192. (185) Chloroplast central 193 
 
 193. (194) Chloroplast an axial plate Mougeotia p. 184 
 
 194. (193) Chloroplasts stellate Zygnema p. 184 
 
 395. (184) Chloroplasts numerous or united to form a single reticulate 
 
 mass Cladophora p. 182 
 
26 
 
 WISCONSIN PHYTOPLANKTON 
 
 Class MYXOPHYCEAE. 
 
 Cells solitary, in colonies of definite or indefinite shape, or in fila- 
 ments but always surrounded by a gelatinous to tough envelope which 
 is generally hyaline but may be colored. Plants living a free-fioating, 
 sessile, epiphytic or endophytic existence. Cell shape various; spheri- 
 cal, hemispherical, ovoid, bacilliform, disciform or angular. Cells with 
 the coloring matter localized at the periphery but not in definite, visible 
 ehromatophores. Color of cells typically blue-green but at times grey, 
 yellowish, reddish, brownish or nearly grass-green. The color variation 
 being due to different amounts of the three component pigments, caro- 
 tin, chlorophyll, and phycocyan; the latter being found only in this 
 class of plants. Cells containing a single nucleus of a primitive type 
 (the central body) that contains linin and chromatin but is without a 
 membrane or nucleole. 
 
 Reproduction always asexual, either by vegetative division of cells; 
 fragmentation of the filaments into smaller portions (hormogones) 
 which may move a short distance by spontaneous movement and then 
 come to rest; or by special non-motile reproductive bodies (gonidia and 
 resting spores) . 
 
 KEY TO THE ORDERS. 
 
 Cells solitary or in colonies, never in filaments Coccogoneau» 
 
 Cells in simple or branched filaments Hobmoqoneaubs 
 
 Order COCCOGONEALES. 
 
 Cells rarely solitary, generally in colonies of regular or irregular 
 shape, and with the cells definitely or indefinitely arranged within a 
 copious gelatinous envelope. Colonies living a free-fioating, sessile, 
 epiphytic or endophytic existence. Cells differentiated into a basal 
 and distal portion or without such differentiation. Cell shape various; 
 spherical, ovoid, cylindrical, acicular, or angular. 
 
 Asexual reproduction by vegetative division of the cells or, in rare 
 cases, by a division of the cell contents into non-motile gonidia. Rest- 
 ing cells and sexual reproduction unknown. 
 
 There are two families in the order only one of which, the Chroococ- 
 caceae, is found in the plankton. 
 
WISCONSIN PHYTOPLANKTON 
 
 27 
 
 Family CHROOCOCCACEAE. 
 
 Cells not differentiated into an apical and basal portion ; rarely soli- 
 tary, generally in colonies of definite or indefinite shape and always 
 enclosed by a gelatinous sheath. Cell shape various, and cellular ar- 
 rangement within the colonial envelope definite or indefinite. 
 
 Asexual reproduction by vegetative cell division and the fragmenta- 
 tion of the colonies. Gonidia formation occasionally taking place in 
 certain genera. 
 
 KEY TO THE GENERA. 
 
 Cells solitary or in colonies that never contain more than a few cells. 
 
 Cells spherical or hemispherical ' Chboocxk'CUS 
 
 Cells longer than they are broad. 
 
 Individual cells or groups of cells enclosed by a gelatinous 
 
 vesicle Gloeothece 
 
 Individual cells or groups of cells without vesicles. 
 
 Ends of cells rounded Rhabdodebma 
 
 Binds of cells pointed Dactylococcopsis 
 
 Cells always. in colonies that contain many cells when mature. 
 
 Cellular arrangement within colony definite. 
 
 Cells forming a flat plate Merismopedia 
 
 Cells forming a hollow sphere one cell in thickness. 
 
 Center of colony with radiating gelatinous strands . Gomphosphaeria 
 
 Center of colony without radiating strands Coelosphaeriem: 
 
 Cellular arrangement within colony indefinite. 
 
 Cells spherical. 
 
 Cells densely aggregated Microcystis 
 
 Cells some distance from one another Aphanocapsa 
 
 Cells longer than they are broad Aphanothbck 
 
 CHROOCOCCUS Nageli 1849. 
 
 Cells spherical, usually hemispherical for some time after division; 
 solitary or 2-4r-8-16 or more united in colonies enclosed by a hyaline 
 or colored, homogeneous or lamellated sheath; free-floating, sessile, or 
 epiphytic. Individual cells of colony at times surrounded by a homo- 
 geneous or lamellated sheath. Cell contents grey, grey-green, blue- 
 green, olive-green, yellowish, orange, reddish or violet in color; homo- 
 geneous or granular. 
 
 Reproduction by vegetative division of cells in three directions. 
 
 KEY TO THE SPECIES. 
 
 Sheaths enclosing cells homogeneous. 
 
 Cells solitary, in twos, and in fours C. Minutes 
 
 Cells in colonies of 4-8-16 or more. 
 
 Individual cells or groups of cells some distance from one 
 
 another C. Disperses 
 
 Individual cells or groups of cells fairly close together . . C. Limneticus 
 
28 
 
 WISCONSIN PHYTOPLANKTON 
 
 Sheaths enclosing cells distinctly lamellated. 
 
 Diameter of cell and sheath not exceeding 40 /x C. Turgidus 
 
 Diameter of cell and sheath over 60 /x C. Giganteus 
 
 Chroococcus Minutus (Kiitzing) Nageli. PL 1, Fig. 1. 
 
 Gatt. einz. Algen 46. 1849. 
 
 Protococcus minutus Kiitzing, Tabulae Phycol. 1: pi. 5. 
 
 Cells spherical or hemispherical, solitary or in colonies of 2-4 en- 
 closed by a wide, spherical, homogeneous, gelatinous sheath. Cell con- 
 tents pale blue-green to grey, homogeneous or granulose. (Tychoplank- 
 tont) . 
 
 Diam. cells (without sheath) 5-7 ix, (with sheath) 6-12 /x; length 
 (without sheath) 5-10 /x, (with sheath) 5-13 /x. 
 
 Wolf (rrr).^ 
 
 Chroococcus dispersus (v. Keissler) Lemmermann. PI. 1, Fig. 2 . 
 
 Arkiv. f. Botanik 2, No. 2: 102. 1904. 
 
 Chroococcus minor var. dispersus v. Keissler, Verh. d. zool.-bot. Ges. Wien 
 52: 311, fig. 6. 1902. 
 
 Cells spherical, 4-16 or more united to form spherical, ovoid, or ir- 
 regular colonies. Individual cells some distance from one another, 
 or in compact groups that lie some distance from one another within 
 the colony. Individual cell sheaths frequently confluent with the col- 
 onial sheath. Cell contents homogeneous, pale to bright blue-green. 
 (Euplanktont). 
 
 Diam. cells (without sheath) 3-4 /x; (with sheath) 6 /x. Distance be- 
 tween cells or groups of cells 15-20 /x. 
 
 Browns (rr), Pokegama (1) (rr). 
 
 A species that is closely related to C. limneticus but one where the 
 number of cells in the colony is usually greater, and where the indi- 
 vidual cells or groups of cells are some distance from one another. 
 
 var. minor var. nov. PI. 1, Fig. 3. 
 
 Cells smaller than the typical form and with pale grey contents. 
 (Euplanktont). 
 
 Diam. cells 1. 75-2. 5 /x. 
 
 Long (3) (rrr), Middle McKenzie (rr). Palmer (rr). 
 
 ♦ The relative abundance of the individual species is shown by the following 
 symbols; (aaa) very abundant, (aa) abundant, (a) fairly abundant, (ccc) very 
 common, (cc) common, (c) fairly common, (s) fairly scarce, (ss) scarce, 
 (sss) very scarce, (r) fairly rare, (rr) rare, (rrr) very rare. 
 
WISCONSIN PHYTOPLANKTON 
 
 29 
 
 Chroococcus Limneticus Lemmermann. PI. 1, Fig. 4. 
 
 Bot. Cent. 76: 153. 1898; Forschungsbr. a. d. Biol. Stat. zu Pl5n 7: 132, pi. 1, 
 
 figs. 22-23. 1899. 
 
 Mature cells spherical to subspherical, 4-32 in a free-floating spheri- 
 cal to ovoid colony. Cells fairly close together and equidistant from 
 one another within the colony, sometimes in groups of 2-4 but with 
 the groups lying close together. Cell division in all three planes but 
 a majority of the cells dividing in the same plane and giving the colony 
 a somewhat tabular appearance. Many hemispherical cells present be- 
 cause of the slow maturation after division. Individual cell sheaths 
 homogeneous and frequently confluent with colonial envelope. Cell 
 contents homogeneous; grey, pale to bright blue-green, or olive-green. 
 (Euplanktont). 
 
 Diam. cells (without sheath) 6-12 fx, (with sheath) 8-14 /t. 
 
 Balsam (r), Bear (1) (rr), Bear (2) (rrr), Bear Trap (sss), Beasley (rr), 
 Beaver (1) (r), Beaver (2) (ss), Big Butternut (r), Birch (1) (rr), Birch (2) 
 (ss), Birch Island (s), Blake (sss). Bloom (s), Boulder (rrr), Browns (s), 
 Camp (rr). Catfish (rr), Chetac (r), Chetek (rrr). Cranberry (sss), Dunham 
 (rr), Dutchmans (r). Eagle (rr). East (rr). Fish (rr). Found (rr), Fowler 
 (rr), Grassy (rr). Grindstone (rr). Half Moon (rr), Horseshoe (1) (r). 
 Island (rr), Kawaguesaga (rr), Kimball (rr), Lac Court Oreilles (rr). Lac la 
 Belle (r). Little Bass (2) (ss). Little Butternut (rr). Little Rice (2) (rr). 
 Little Wood (sss), Loveless (r), Mary (rr). Middle McKenzie (r). Mill (rr), 
 Mud (1) (rr). Mud (2) (rr), Mudhen (r), Nicaboyne (r). North Twin (rr), 
 Oconomowoc (rr). Old Taylors (rr), Pewaukee (rr). Pike (rr). Pine Tree (rr), 
 Pokegama (1) (r), Pokegama (2) (rrr), Pokegama (3) (rr). Poor Farm (rr). 
 Poplar (ss). Reserve (sss). Rice (1) (r), Round (3) (rr). Sand (1) (s). 
 Sand (3) (sss). Sand (4) (rr). Shell (sss), Silver (2) (r). Spirit (r). Squir- 
 rel (r). Tenderfoot (rrr), Travis (rrr). Upper Nashotah (rr). Upper Nemah- 
 bln (rr). White Ash (ss), Whitefish (s). Wildcat (rr), Winnebago (r). Wolf 
 (rr). 
 
 This is preeminently a plankton species. It is widely distributed 
 throughout the state and may be the dominant member of the Myxo- 
 phyceae in lakes with very soft water, but it never occurs in sufficient 
 abundance to cause the familiar phenomenon of blooming. The cells 
 are quite variable in both color and size. 
 
 var. SUBSAI..SUS Lemmermann. PI. 1, Fig. 5. 
 
 Forschungsbr. a. d. Biol. Stat. zu P16n 8: 84. 1901; Arkiv f. Botanik 2: No. 2: 
 
 101, pi. 1, fg. 9. 1904. 
 
 Cells spherical to subspherical, 8-16-32 in a somewhat spherical or 
 broadly ellipsoidal colony with a wide gelatinous envelope. Cell con- 
 tents homogeneous; pale to bright blue-green. (Euplanktont). 
 
30 
 
 WISCONSIN PHYTOPLANKTON 
 
 Diam. cells (without sheath) 3. 5-4.5 /x; (with sheath) 4.5-5.5 fi. 
 
 Big Bass (sss), Blake (rr), Lac Court Oreilles (ss), Owen (ss), Paddock (r). 
 
 The chief distinction of this and the following varieties is in the size 
 of the cells. 
 
 var. CARNEUS (Chodat) Lemmermann. PI. 1, Fig. 6. 
 
 Arkiv for Botanik 2, No. 2: 101. 1904. 
 
 Cells spherical to hemispherical, 4-8-16 irregularly distributed 
 throughout a spherical to ovoid gelatinous matrix. Individual sheaths 
 of ceUs confluent with the colonial envelope. Cell contents homogene- 
 ous; color variable, ochraceous, grey, blue-green or olive green. (Eu- 
 planktont) . 
 
 Diam. cells (without sheath) 7-9 fi. 
 
 Big Bass (ss), Harris (r), Mendota (rr), Nancy (r), Oconomowoc (rr). 
 
 var. DiSTANS G. M. Smith. PI. 1, Pig. 7. 
 
 Bull. Torr. Bot. Cl. 43: 481, pi. 26, fig. 26. 1916. 
 
 Cells spherical to hemispherical, 8-32 in a colony and lying some 
 distance from one another within a spherical to ovoid, hyaline, homo- 
 geneous, gelatinous, colonial envelope. Individual cell sheaths con- 
 fluent with the colonial envelope. Cell contents homogeneous, grey to 
 pale blue-green in color. (Euplanktont). 
 
 Diam. cells (without sheath) 6.5-7 /x. 
 
 Bear Trap (s), Birch Island (rr), Browns (sss), Cochrane (r). Cranberry 
 (sss), Lindy (rr), Muskallonge (rr). 
 
 var. ELEGANS G. M. Smith. PI. 1, Pig. 8. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 619. 1918. 
 
 Cells circular to semicircular in front view, somewhat flattened in 
 side view. Colonies enclosed by a spherical, homogeneous, hyaline, gel- 
 atinous envelope. Individual sheaths of cells conspicuous. Cell con- 
 tents homogeneous; generally bright blue-green in color. (Euplank- 
 tont). 
 
 Diam. cells (without sheath) 18-22 fx; (with sheath) 20-26 /x. 
 
 Delavan (rr). 
 
 Chroococcus giganteus W. West. PI. 2, Pig. 1. 
 
 Jour. Roy. Micr. Soc. 1892: 741, pi. 10, figs. 59-60. 1892. 
 
 Cells ordinarily hemispherical, rarely becoming spherical or ovoid 
 after division. Solitary or in colonies of two (rarely 3-4) enclosed by 
 
WISCONSIN PHYTOPLANKTON 
 
 31 
 
 a thick, hyaline, markedly lamellate, gelatinous envelope. Envelope of 
 individual cells conspicuous, lamellated. Cell contents distinctly gran- 
 ulose, bright blue-green. (Tychoplanktont). 
 
 Diam. cells (without sheath) 54—58 ix\ (with sheath) 67-70 /x. 
 
 Mary (rrr). 
 
 Chroococcus turgidus (Kiitzing) Nageli. PI. 1, Fig. 9. 
 
 Gatt. einz. Algen 46. 1849; G. S. West, Brit. Fresh w. Algae 352, fig. 166g. 1904. 
 
 Cells hemispherical, spherical, ovoid, or somewhat flattened by mutual 
 compression. Cells solitary or in colonies of 2-4 (rarely 8) enclosed 
 by a thick, hyaline, generally lamellated, gelatinous sheath. Individual 
 cells also with hyaline, lamellated sheaths. Cell contents homogeneous 
 or finely granulose; pale to bright blue-green or rarely brownish in 
 color. ( Tychoplanktont ) . 
 
 Diam. cells (without sheath) 8-32 /x; (with sheath) 13-40 /x. 
 
 Beasley (rrr), Beaver (2X (rr). Browns (rr), Hillman (rr), Horse (rrr), 
 Oconomowoc (rr), Otter (rr), Rudolph (rr). Sand (2) (rr), Upper Turtle (rr), 
 Waubesa (rrr). 
 
 MERISMOPEDIA Meyen 1839. 
 
 Colonies always forming flat, curved, or irregularly twisted plates 
 one cell in thickness with the constituent cells in rectilinear series and 
 usually in groups of four.' Cells spherical to subspherical with rounded 
 ends, hemispherical for some time after division. Individual sheaths 
 of cells rarely distinct, generally confluent with the copious, hyaline, 
 homogeneous, colonial envelope. Number of cells in colony 4 — 4(K)0, 
 cell number a multiple of two in young colonies, not a multiple of two 
 in old colonies. Cell contents generally homogeneous, rarely with 
 pseudovacuoles. Color varying from grey through light to bright blue- 
 green, rarely rose pink to violet. 
 
 KEY TO THE SPECIES. 
 
 Cells bright blue-green M. Elegans 
 
 Cells pale blue-green. 
 
 Cells some distance from one another M. Punctata 
 
 Cells close together (not mutually compressed). 
 
 Diameter of cells 1. 5-2 /x M. Tenuissima 
 
 Diameter of cells 3-6 /x M. Glauca 
 
32 
 
 WISCONSIN PHYTOPLANKTON 
 
 Merismopedia elegans a. Braun. PL 2, Fig. 6. 
 
 in Kiitzing, Species algarum 472. 1849; G. S. West, Brit. Fresh w. Algae 348: 
 fig. 162^. 1904. 
 
 Colonies small or large, of 16-4000 cells regularly arranged in recti- 
 linear series and groups of four; with the cell number a multiple of 
 two in young colonies but becoming irregular in arrangement and num- 
 ber in old colonies. Colonies flat except when containing many cells. 
 Cells spherical to broadly ovoid, with homogeneous, bright blue-green 
 contents. (Facultative Planktont). 
 
 Cells 5-7 /A broad, 5-9 fi long. 
 
 Carson (rr), Center (rr), Green (1) (rr), Kegonsa (rr), Little Bear (rrr), 
 Mendota (r), Monona (r), Mud (1) (rr), Nancy (r), Upper Nashotah (rrr), 
 Waubesa (rr). 
 
 This alga is a good example of a typical benthitic organism that is 
 able to thrive under limnetic conditions. It never becomes a conspicu- 
 ous member of the plankton but the colonies attain a much larger size 
 and I have observed specimens 60-70 cells broad and 60-90 cells long. 
 There is a certain amount of irregularity in such colonies so exact de- 
 terminations of cell numbers are impossible. 
 
 var. major var. nov. PL 2, Fig. 6. 
 
 Colonies usually containing many cells. Cell shape the same as in 
 the typical form'. Cell contents homogeneous, bright blue-green. (Bu- 
 planktont). 
 
 Cells 10-11 fi broad, 12-14 /jl long. 
 
 Beaverdam (r), Lindy (rr). 
 
 Merismopedia glauca (Ehrenberg) Nageli. PL 2, Fig. 4. 
 
 Gatt. einz. Algen 56, pi. 1, fig. IP. 1849. 
 
 Colonies generally containing less than 64 cells, compactly and regu- 
 larly arranged. Cells spherical to broadly ellipsoid, hemispherical for 
 some time after division. Cell contents homogeneous, generally pale 
 blue-green. (Facultative Planktont). 
 
 Diam. cells 3-5 jm. 
 
 George (rr), Jones (rrr). Lac Court Oreilles (rrr). Loon (rrr), Meta (rr), 
 Mill (rr), Waubesa (rr). 
 
 This species resembles M. punctata in the size of the cells but differs 
 in the distance between the cells. 
 
WISCONSIN PHYTOPLANKTON 
 
 33 
 
 Merismopedia punctata Meyen. PI. 2, Fig. 3. 
 
 Arch. f. Naturgesch. 5*: 67. 1839; Kiitzing, Tabulae Phycol. 5: 18, pi. 38, /Ip. 3. 
 1855. 
 
 Colonies small, with the cells some distance from one another but 
 regularly arranged in rectilinear series. Cells spherical to broadly 
 ovoid or hemispherical. Cell contents homogeneous, grey to pale blue- 
 green. (Tychoplanktont). 
 
 Diam. cells 2.5-3.5 /x. 
 
 Big Bass (rrr). 
 
 Merismopedia tenuissima Lemmermann. PI. 2, Fig. 2. 
 
 Bot. Cent. 76: 154. 1898; Forschungsbr. a. d. Biol. Stat. zu P15n 7: 132, pi. 1, 
 Hg. 21. 1899. 
 
 Colonies rectangular, free-floating, generally with 16-100 cells lying 
 close together. Rectilinear arrangement of cells soon breaking down 
 and not evident when there are more than 32 cells in a colony. Col- 
 onies distorted when of any size. Cells spherical to ovoid, hemispheri- 
 cal for some time after division. Individual sheath of cells distinct 
 or confluent with colonial envelope. Cell contents homogeneous; grey 
 to pale blue-green. (Facultative Planktont). 
 
 Diam. cells (without sheath) 1.5-2 /x. 
 
 Camp (rr), Little Doctor (rr), Long (3) (r), Mary (rr). 
 
 The irregular cellular arrangement is very common in older colonies 
 and is not due to the size of the colony, since the species is one of the 
 smallest of the genus, but to irregularities in cell division. 
 
 COELOSPHAERIUM Nageli 1849. 
 
 Colonies microscopic, free-floating; spherical, ellipsoid, reniform, or 
 irregular ; enclosed by a delicate, hyaline, homogeneous or radially fibril- 
 lar, gelatinous envelope. Cells spherical, ovoid, ellipsoid, sub-pyriform 
 and arranged in a single layer to form a hollow sac just beneath the 
 periphery of the colonial envelope. Cell contents homogeneous and 
 grey to bright blue-green ; or reddish and containing numerous pseudo- 
 vacuoles.* 
 
 Reproduction by vegetative cell division in three directions. 
 
 ♦These structures, which are also called gas vacuoles, are found in certain 
 plankton species of the Myxophyceae. They are minute bodies, which are 
 reddish through their refractive power, that occur in large numbers in all 
 cells of the colony. Various functions have been ascribed to them, the most 
 probable being a means of protection against too intense light, or a giving of 
 greater buoyancy to the colony. 
 
 3 
 
34 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Cells spherical. 
 
 Diameter of cells not exceeding 4 C. Kuetzingiaum 
 
 Diameter of cells over 5 C. Dtjbium 
 
 Cells ovoid to ellipsoid C. Naegblianum 
 
 CoELOSPHAERiUM KuETZiNGiANUM Nageli. PI. 3, Figs. 4-5. 
 
 Gatt. einz. Algen 54, pi. 1, fig. C. 1849. 
 
 Colonies spherical to subsplierical, enclosed by a very hyaline, homo- 
 geneous, gelatinous envelope. Cells spherical to subspherical, forming 
 a single layer, with the individual cells or pairs of cells some distance 
 from one another or close together. Cell contents homogeneous, with- 
 out pseudovacuoles ; usually grey to pale blue-green, rarely bright blue- 
 green. (Facultative planktont). 
 
 Diam. cells 2.25-4 /x ; diam. colonies 20-90 /x. 
 
 Balsam (rr), Bass (2) (rr). Bear (3) (r), Bear Trap (rrr), Beaverdam (ss), 
 Big (ss). Big Butternut (sss), Birch Island (rrr), Blake (ss), Bone (rr). 
 Browns (rr), Carson (r). Catfish (r). Clam (ss), Cochrane (sss), Crab (rr). 
 Cranberry (ss). Crawling Stone (sss), Deer (rr). Diamond (rrr), Elizabeth 
 (s). Eagle (ss). Fence (sss). Fish (rr), Grindstone (rr). Green (2) (rr). Half 
 Moon (r). High (sss), Hillman (ss). Horseshoe (1) (rrr), Kegonsa (s). Kit- 
 ten (rr). Island (ss). Lac la Belle (rr), Lindy (rr). Little Bear (rrr). Little 
 Butternut (r). Little Crooked (rr). Little Rice (1) (ss). Little Wood (s), 
 Long (2) (rr). Long (3) (rr). Loveless (sss), Mary (s), Mendota (s), Mer- 
 cer (rrr). Mill (rrr). Mud (1) (cc). Mud (2) (r), Mudhen (s), Nancy (rrr), 
 Nicaboyne (rr), North Turtle (ss), Oconomowoc (r), Owen (rrr). Paddock 
 (ss). Palmer (ss), Pardee (cc), Pewaukee (rr). Pine (2) (rr). Fine Tree (rr), 
 Pokegama (1) (sss), Pokegama (2) (r), Pokegama (3) (rrr). Poplar (ss), 
 Reserve (ss). Rice (1) (rr). Rock (sss). Round (3) (sss). Sand (1) (rr), 
 Sand (3) (rr). Sand (4) (r). Silver (1) (ccc). Silver (2) (ss), South Turtle 
 (ss), Spirit (ss), iSunday (r). Tamarack (rr). Tenderfoot (sss). Tied Canoe 
 (rrr). Upper Nemahbin (rrr). Upper Turtle (sss). White Ash (sss). White- 
 fish (s), W’hite Sand (sss). Wildcat (rr). Wild Goose (rr), Winnebago (rr). 
 Wolf (r). 
 
 The gelatinous sheath is generally so delicate that it is necessary to 
 use Errera’s method of mounting colonies in dilute India ink to demon- 
 strate its presence. The specific limits of this species as established 
 by different authors frequently includes C. Naegelianum as a synonym. 
 C. Kuetzingianum and C. Naegelianum are two well defined species that 
 differ in colony shape^ cell shape, occurrence of pseudovacuoles, struc- 
 ture of colonial envelope, and relative abundance. C. Kuetzingianum 
 is a species that is widely distributed throughout the state but one which 
 rarely becomes a dominant member of the plankton and never occurs 
 in sufficient abundance to cause blooming. 
 
V/I8C0NSIN PHYTOPLANKTON 
 
 35 
 
 CoELOSPHAERiuM DUBiUM Grunow. PI. 3, Fig. 7. 
 
 in Rabenhorst, Flora Eur. Algarum 2: 55. 1865; Scbmula, Beibl. z. Hedwigla 
 S7: (47), figs. 1-2. 1898. 
 
 Colonies spherical to irregular, with three or four smaller colonies 
 frequently enclosed by a common gelatinous envelope. Colonial en- 
 velope firm, hyaline, and homogeneous. Cells in a single layer and 
 very close together at the periphery of the colonial envelope. Cell con- 
 tents homogeneous or with p seudo vacuoles ; blue-green in color. (Fac- 
 ultative Planktont). 
 
 Cells 5-7 fx in diameter. Single colonies up to 150 /x in diam ; com- 
 pound colonies up to 300 fx. 
 
 Mud (3) (rr). 
 
 CoELOSPHAERiUM Naegelianum Unger. PI. 3, Fig. 6; PI. 4, Fig. 1. 
 
 Denkschr. d. kais. Ak. d. Wiss. Wien 7: 196. 1854; Leitgeb, Mitt. d. naturw. 
 
 Ver. Steiermark 2, Heft 1: 72, pi. 2, figs. 1-6. 1869; Borge, Bot. Not. 1900: 
 
 10, pi. 1, figs. 5a-5b. 1900. 
 
 Gomphosphaeria Naegeliana (Unger) Lemmermann. Kryptogamenfl. d. 
 Mark Brandenburg 3, Algen 1: 80, 44, fig. 19. 1907; Bachmann, Arch. f. Hy- 
 
 drobiol. u. Planktonkde. 3: 60, figs. IIP-IIP. 1908. 
 
 Colonies spherical, ovoid, renif orm or irregular ; with a wide, hyaline, 
 gelatinous envelope that is at times radially fibrillar in structure. Cells 
 ovoid to ellipsoid, radially arranged in a single layer some distance be- 
 neath the periphery of the colonial envelope, usually close together but 
 not mutually compressed. Cell contents rarely homogeneous and pale 
 to bright blue-green or grass-green ; usually with numerous pseudovacu- 
 oles and reddish to brownish in color. (Euplanktont). 
 
 Cells 2-3 IX broad ; 3.5-6 /a long. 
 
 Adelaide (ss), Amicoy (ss). Balsam (ss). Bear (1) (s). Bear (2) (rr), 
 Bear (3) (s), Bear Trap (sss), Beaverdam (cc). Big (ccc). Big Butternut 
 (r). Big McKenzie (ss). Big St. Germaine (rr), Birch (1) (ccc), Birch (2) 
 (aa), Birch Island (rrr), Blake (rr). Bloom (ss), Bone (ss), Boulder (rr). 
 Browns (rr), Camp (c). Catfish (aa), Center (aa), Chetac (aa). Clam (c), 
 Clare (rr). Crab (sss). Cranberry (aa). Devils (1) (rr). Devils (2) (ss). 
 Deer (rr). Duck (c). Dummy (rrr), Elizabeth (cc), Fish (sss). Found (ss), 
 Fowler (ss), Granite (ss). Grindstone (rr). Half Moon (s), Hillman (s). 
 Hooker (rr). Horseshoe (1) (ss). Horseshoe (2) (rrr). Island (cc), Jennie 
 (rr), Kawaguesaga (sss). Kitten (rrr), Kegonsa (aa). Lac du Flambeau (rr), 
 Lac la Belle (r), Laura (aa), Lindy (rr). Little Bass (2) (rr). Little Butter- 
 nut (rr). Little Rice (1) (cc). Long (1) (rr). Long (2) (a). Loon (rr). Lost 
 (aa), Lower Nemahbin (r). Marl (rr), Mendota (cc), Mercer (ss), Middle 
 McKenzie (cc), Mill (rr), Minocqua (rr), Monona (aa). Mud (1) (cc). Mud 
 (3) (aa), Mudhen (rr), Nancy (c), Nicaboyne (r). No Mans (aa). North 
 Twin (cc). North Turtle (aa). Number One (ss), Oconomowoc (rr), Okauchee 
 
WISCONSIN PHYTOPLANKTON 
 
 rfb 
 
 (r), Otter (rr). Paddock (c), Palmer (ss), Pardee (rr), Pewaukee (ss), 
 Plum (ss), Pokegama (1) (c), Pokegama (2) (sss), Pokegama (3) (a), Pop- 
 lar (r), Prairie (s), Reserve (ss), Rainbow (r), Rice (1) (cc), Rock (a), 
 Rooney (aa). Round (1) (rrr). Round (2) (ss), Round (3) (ss), St. Croix 
 (cc), Sanford (r), Sand (1) (ss). Sand (2) (rr), Sand (3) (rr), Sand (4) 
 (rr). Silver (2) (c), tSishebogema (aa). South Turtle (sss). Upper Nashotah 
 (rr). Upper Nemahbin (rr). Upper Turtle (s), Wapagossett (cc), Waubesa 
 (cc). White Ash (rr), Whitefish (cc). White Sand (rrr). Wildcat (rrr), Win- 
 nebago (cc),WoK (rrr). 
 
 The radial fibrillar structure at the periphery of the gelatinous en- 
 velope is also found at times in the center of the colony. These radia- 
 tions have been compared by some to the gelatinous strands found in 
 GomphospJiaeria and the species transferred to that genus. I have 
 preferred to keep the alga in the genus where it was first described. 
 This alga is one of the important members of the Myxophyceae in the 
 formation of blooms but it is rarely found as the sole constituent of 
 any bloom. Bachmann’s figures of the alga are quite characteristic. 
 
 GOMPHOSPHAERIA Kiitzing 1836. 
 
 Colonies microscopic, spherical to ellipsoid, embedded in a copious, 
 hyaline, solid, homogeneous, gelatinous envelope. Cells spherical 
 to pyriform, solitary or in pairs, generally lying some distance from 
 one another and forming a layer one cell in thickness towards the pe- 
 riphery of the colonial envelope. Central portion of colonial envelope 
 containing a denser core from which projections radiate to the base of 
 the cells. Individual sheaths of cells distinct or confluent with the 
 colonial envelope. Cell contents homogeneous, rarely granulose; grey 
 to light or bright blue-green. 
 
 Reproduction by alternate vegetative division of cells in three planes. 
 
 KEY TO THE SPECIES. 
 
 Cells spherical G. Lacustris 
 
 Cells pyriform to cardioid G. Afonina 
 
 Gomphosphaeria lacustris Chodat. PI. 4, Fig. 5. 
 
 Bull. Herb. Boiss. 6: 180, figs. 1898; W. & G. S. West, Trans. Roy. Irish 
 
 Acad. 33, Sec. B: 112, pi. 11, figs. 24-27. 1906. 
 
 Colonies small, generally spherical or subspherical, rarely reniform; 
 with a hyaline, homogeneous, gelatinous envelope. Cells spherical to 
 broadly ellipsoid, irregularly spaced to form a single layer one cell in 
 thickness beneath the periphery of the colonial envelope. Individual 
 cell sheaths confluent with colonial envelope. Central portion of col- 
 ony containing a core of denser radiating gelatinous strands that run 
 
WISCONSIN PHYTOPLANKTON 
 
 37 
 
 to the base of the cells. Cell contents homogeneous; grey to pale or 
 bright blue-green, rose colored in rare instances. (Euplanktont). 
 Cells 1. 5-2.5 IX broad, 1.5-4 /x long. Colonies rarely over 40 fx in diam. 
 
 Bear (1) (rr), Beaverdam (c), Big McKenzie (ss), Blake (sss)^ Cochrane 
 (r), Deer (rr), Diamond (r), Dunham (c), Fish (c), Half Moon (rr). Island 
 (rr), Kawaguesaga (r). Lac Court Oreilles (ss), Llndy (sss). Little Bass (2) 
 (rr), Long (1) (rr). Loon (rr), Mendota (s), Mercer (ss). Middle McKenzie 
 (ss), Mudhen (ss), Nicaboyne (r). North Twin (r), Pardee (rr). Plum (rr), 
 Pokegama (3) (rr). Sand (1) (r). Sand (2) (rr). Sand (4) (rr), Spirit (r), 
 Squirrel (sss). Star (sss), Wolf (r). 
 
 The colonies of this species resemble those of Coelosphaerium Kuetz- 
 ingianum in cell shape and arrangement but differ in the radiating 
 strands of gelatinous material running from the center of the colony 
 to the base of the cells. The gelatinous envelope is very delicate and 
 cells frequently break away leaving the central mass of gelatinous radi- 
 ations floating by itself. 
 
 Gomphosphaeria aponina Kiitzing. PI. 4, Figs. 2-3. 
 
 Decades 16: No. 151. 1836; G. S. West, Brit. Freshw. Algae 349, fig. 163g. 
 1904. 
 
 Colonies small, spherical to subspherical, with a fairly thick, hya- 
 line, homogeneous, gelatinous envelope. Cells pyriform to cuneate, 
 cardioid just before division; sparsely scattered and in a single layer 
 some distance beneath the periphery of the colonial envelope. Indi- 
 vidual sheaths of cells generally distinct, attached at the base to the 
 dense gelatinous strands radiating from the center of the colony. Cell 
 contents homogeneous or finely granulose; without pseudovacuoles; 
 generally a bright blue-green. (Tychoplanktont). 
 
 Cells 4-5 fx wide at the greatest breadth, 8-15 /x long. Diam. colonies 
 50-90 fx. 
 
 Beaverdam (sss). Big McKenzie (rrr). Browns (rr). Center (rr), Eagle 
 (rr), Elizabeth (rr), Hillman (rr), Kegonsa (rrr). Lower Nemahbin (rr), 
 Mendota (rr), Mary (rr), Monona (rrr), Mudhen (rr). North Turtle (rrr). 
 Otter (rrr), Pewaukee (rr). Pine (1) (rrr). Plum (rrr). Silver (2) (rr), Sil- 
 ver (3) (rr). South Turtle (rr), Waubesa (r). 
 
 var. coRDiFORMis Wolle. PI. 4 , Fig. 4 . 
 
 Bull. Torr. Bot. Cl. 9: 25, pi. 13, fig. 11. 1882. 
 
 Cells considerably larger than in the typical form and markedly 
 heart shaped instead of pyriform. Individual sheaths of cells conspicu- 
 ous. Cell contents bright blue-green. (Tychoplanktont). 
 
 Greatest breadth of cells 6-13 fx ; length 9-20 /x. 
 
 Bloom (rrr). 
 
38 
 
 WISCONSIN PHYTOPLANKTON 
 
 The cells of the Wisconsin individuals are somewhat longer than 
 Wolle found them, his measurements for the length of the cell varying 
 from 9-16 fi. 
 
 MICROCYSTIS Kiitzing 1833. 
 
 Colonies free-floating; spherical, elongate, irregular, or perforate to 
 form reticulate or clathrate masses of microscopic or macroscopic size. 
 Frequently occurring in sufficient quantities to give the water a verdi- 
 gris-green color. Envelope of colonies generally copious, delicate to 
 firm. Cells small, spherical, distributed in a solid mass throughout the 
 colony and densely aggregated. Individual cell sheath confluent with 
 colonial envelope. Cell contents homogeneous or with numerous pseudo- 
 vacuoles ; light to dark blue-green, olive-green, or rose colored. 
 
 Reproduction by vegetative division of cells in three directions. 
 
 Certain species of the genus occur in prodigious quantities and cause 
 the familiar blooming of lakes. These species contain pseudovacuoles, 
 while species without pseudovacuoles rarely occur in quantity. 
 
 KEY TO THE SPECIES. 
 
 Cells with numerous pseudovacuoles. 
 
 Several colonies enclosed by the same envelope M. Ichthyoblabe 
 
 Colonies not differentiated into several within the same envelope. 
 
 Colony entire, not perforate M. Flos-Aquae 
 
 Colony saccate and perforate M. Aeruginosa 
 
 Cells without pseudovacuoles. 
 
 Diameter of cells less than 1.5 /x M. Inceeta 
 
 Diameter of cells 2-3 jx M. Pulvera 
 
 Microcystis ichthyoblabe Kiitzing. 
 
 Phycol. generalis 170. 1843. 
 
 Polycystis ichthyoblabe Kiitzing, Tabulae Phycol. 1: 7, pi. 8. 1845. 
 
 Colonies spherical or irregular, fragmented into several distinct sub- 
 colonies, each with its own gelatinous envelope, and with the sub-col- 
 onies enclosed by a common gelatinous envelope. Cells spherical, close 
 together. Individual cell sheaths confluent with colonial envelope. Cell 
 contents pale to bright blue-green. Generally containing numerous 
 pseudovacuolcs. (Facultative Planktont). 
 
 Diam. cells 2^ /x. 
 
 Catfish (rr), Clear (rr), Kawaguesaga (ss), Minocqua (r). 
 
WISCONSIN PHYTOPLANKTON 
 
 39 
 
 Microcystis FLOS-AQUAE (Wittrock) Kirckner. PL 5, Fig. 1. 
 in Engler & Prantl, D. nat. Pflanzenfam. 1 (Abt. 1&) : 56, fig. 49j^. 1900. 
 
 Colonies spherical to ovoid, rarely elongate ; frequently reaching a 
 macroscopic size. Cells compactly and evenly distributed within a very 
 delicate, hyaline, homogeneous, gelatinous envelope. Margins of colony 
 not sharply defined. Cell contents rarely homogeneous and grey to 
 pale blue-green; usually with pseudovacuoles and reddish in color. 
 Plant mass yellowish to verdigris-green. (Euplanktont). 
 
 Diam. cells 3. 5-6.5 ju,. 
 
 Bear (2) (rr), Big St. Germain (rr), Birch (1) (c), Birch Island (sss), 
 Browns (cc), Catfish (ss), Center (ss), Cochrane (sss), Duck (ss), Dunham 
 (rr), Pishtrap (rr). Found (sss), Fowler (rr), High (rr). Horseshoe (1) (rr), 
 Kegonsa (cc). Loveless (r). Lower Nashotah (rr). Lower Nemahbin (r), 
 Mendota (aa), Mercer (rrr), Monona (aa). Mud (3) (cc), Nagawicka (rr). 
 No Mans (r). North Turtle (ss), Oconomowoc (ss). Paddock (ss). Palmer (ss), 
 Pardee (ss). Plum (ss), Pokegama (1) (ss), Rainbow (r). Rock (s). Rose 
 (ss). Sand (3) (r). Shell (rr), Sishebogema (ss). South Turtle (ss). Squirrel 
 (rr), Star (ss). Tamarack (ss). Tenderfoot (rr). Upper Nashotah (rrr), Wapa- 
 gossett (ss), Waubesa (ss), Whitefish (ss), Winnebago (cc). 
 
 Microcystis aeruginosa Kiitzing. PI. 5, Figs. 2-3. 
 
 Tabulae Phycol. 1: 6, pi. 8. 1845. 
 
 Clathrocystis aeruginosa (Kiitzing) Henfrey, Trans. Micr. Soc. London N. S. 
 4: 53, pi, 4, figs. 28-36. 1856 (in Quart. Jour. Micr. Sci. 4: 1856): Bachmann, 
 Arch. f. Hydrobiol. u. Planktonkde. 3: 61, figs. IW-IV®. 1908. 
 
 Colonies spherical to subspherical when young, later becoming saccate 
 and ultimately reticulate and clathrate. Gelatinous envelope of colony 
 homogeneous, hyaline, and indistinct. Colonies frequently occurring 
 in sufficient quantity to color water a bright green. Cells spherical to 
 subspherical, evenly distributed throughout the colony and close to- 
 gether. Cell contents rarely homogeneous and grey to pale or bright 
 blue-green; usually with numerous pseudovacuoles and reddish. (Eu- 
 planktont). 
 
 Diam. cells 3-4 p. 
 
 Balsam (ss). Bear (3) (rr). Big Butternut (ss). Bloom (ccc). Bone (ss). 
 Browns (cc). Center (rr). Clam (r). Crooked (rrr), Delavan (sss), Desmoines 
 (ss). Devils (2) (rr). Duck (rr), Dutchmans (rrr). Eagle (ccc), Elizabeth 
 (cc). Pish (ss), Fowler (rr). Grassy (ss). Grindstone (rr). Half Moon (ss). 
 Hooker (ss). Horseshoe (1) (rr), Kawaguesaga (rr), Kegonsa (a), Kimball 
 (ss). Lac du Flambeau (rr), Lac la Belle (rr). Lake of the Woods (r). Little 
 Bass (2) (sss). Little Butternut (cc), Little Crooked (ss). Little Wood (ss), 
 Loveless (ss), Mendota (a), Meronk (ss). Mill (sss), Monona (cc). Mud (2) 
 (r), Mudhen (ss), Nancy (ss), Nicaboyne (ss). North Turtle (ss), North 
 Twin (cc), Oconomowoc (rrr). Old Taylors (r), Otter (rr), Owen (rrr), Par- 
 dee (ss), Pewaukee (ss), Pokegama (2) (rr), Pokegama (3) (ss), Prairie 
 
40 
 
 WISCONSIN PHYTOPLANKTON 
 
 (S8S), Rice (1) (rr), Rooney (r). Sand (1) (ss), Sand (4) (rr), Shell (rr), 
 Silver (2) (ss), Travis (rr), Upper Turtle (ss), Waubesa (cc). White Ash 
 (sf). Wildcat (ss). Wolf (rr). 
 
 var. MAJOR (Wittrock) G. M. Smith. PL 4 , Fig. 6 . 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18 *: 535. 1916. 
 
 Mature colonies elongate; irregular, saccate, or clathrate. Colonial 
 envelope much firmer than in typical form and with larger cells. (Eu- 
 planktont) . 
 
 Diam. cells 5.5-G.5 fi. 
 
 Center (rr), Mendota (ss), Nancy (sss), St. Croix (rr). Vermilion (cc). 
 
 Microcystis incerta Lemmermann. PI. 5, Fig. 4 . 
 
 Abh. Naturw. Ver. Bremen 17: 342. 1903; Kryptogamenfl. d. Mark Branden- 
 
 burg 3; Algen 1 : 76, 44, fig. 12. 1907. 
 
 Colonies spherical or somewhat elongate, enclosed by a hyaline, homo- 
 geneous, and very delicate gelatinous envelope. Cells small, very close 
 together but equidistant from one another. Cell contents homogeneous, 
 without pseudovacuoles; grey to pale blue-green in color. (Faculta- 
 tive Planktont) . 
 
 Diam. cells 1-2 fi. 
 
 Camp (rr), Chetek (r). Hooker (s). Prairie (r), Whitefish (rr), Winne- 
 bago (c). 
 
 The cells of this species are very similar in appearance to those found 
 in Aphanocapsa elachista and A. delicatissima but their compact ar- 
 rangement shows that the alga is a 3Iicrocystis and not an Aphanocapsa. 
 
 Microcystis pulvera (Wood) Migula. 
 
 in Thomd, Flora v. Deutschl., Deutsch.-Osterr. u. d. Schw. 6, Kryptogamen 2, 
 Algen 1:36. 1907. 
 
 Anacystis pulverus Wood. Wolle, Preshw. Algae of U. S. 329, pi. 210, fig. 25. 
 1887. 
 
 Colonies spherical or elongate, with a very delicate, hyaline, gela- 
 tinous envelope. Cells spherical, very closely crowded together and 
 forming a solid mass. Cell contents homogeneous, without pseudovacu- 
 oles ; grey, pale olive-green, or blue-green in color. (Facultative Plank- 
 tont) . 
 
 Diam. cells 2-3 p. 
 
 Browns (rr), Mill (rrr), Pardee (ss), Sunday (r), Winnebago (sss). 
 
 Since the specific difference between this and the foregoing species 
 is mainly one of cell size it might be better to consider M. incerta a 
 variety of M. pvlvera. 
 
WISCONSIN PHYTOPLANKTON 
 
 41 
 
 APHANOCAPSA Nageli 1849. 
 
 Cells united to form spherical, ovoid, or amorphous colonies of micro- 
 scopic or macroscopic size. Colonies, hyaline, yellow, brown, or blue- 
 green in color. Cells spherical, equally distributed throughout the 
 colony but always some distance from one another; generally solitary, 
 rarely in clusters. Individual sheaths of cells confluent with the homo- 
 geneous, hyaline or colored, colonial envelope. Cell contents homogene- 
 ous ; usually pale to bright blue-green or grey in color. 
 
 Reproduction by vegetative division of cells in three directions. 
 
 KEY TO THE SPECIES. 
 
 Cells growing within gelatinous envelope of other algae A. Endophytica 
 
 Cells forming free-floating or sessile colonies. 
 
 Cell contents grey to pale blue-green. 
 
 Diameter of cells 3. 5-4. 5 fi A. Pulchra 
 
 Diameter of cells less than 3 At. 
 
 Cell diameter not exceeding 1 fx A. Delicatissima 
 
 Cell diameter 1.5-2.5 fx A. Elachista 
 
 Cell contents brightly colored, generally blue-green. 
 
 Diameter of cells 3.5-5 fx A. Grevillei 
 
 Diameter of cells 5-6 a* A. Rivularis 
 
 Aphanocapsa delicatissima W. & Gr. S. West. PI. 2, Fig. 7. 
 
 Jour. Linn. Soc. Bot. 40 : 431, yl. 19, -figs. 2-3. 1912. 
 
 Colonies small, spherical, ovoid or irregular, free-floating. Colonial 
 envelope gelatinous, homogeneous, hyaline or ochraceous. Cells spheri- 
 cal, very small, more or less remote from one another. Cell contents 
 homogeneous, grey to pale blue-green. (Euplanktont). 
 
 Cells .5-.75 fx in diam. ; colonies 15-30 fx broad, 15-50 lonar. 
 
 Big Butternut (r). Chain (r), Little Butternut (ss). Loveless (ss), Mendota 
 (s), Poor Farm (r). 
 
 The cells of this species are smaller than many bacteria and during 
 the first two year ^s study of the plankton flora these small colonies were 
 considered bacteria and not recorded so that the record for distribution 
 is far from complete. When the colonies are of any considerable size 
 the mass of cells has a decided blue-green color so that the organism 
 must be called a blue-green bacterium or a blue-green alga of bacterial 
 size. The latter view seems to be the more logical. It is very probable 
 that the bacteria have been derived from the blue-green algae and the 
 Wests’ discovery of blue-green algae of bacterial size is very suggestive. 
 
42 
 
 WISCONSIN PHYTOPLANKTON 
 
 Aphanocapsa elachista var. conferta W. & G. S. West. PL 2, Fig. 8. 
 Jour. Linn. Soc. Bot. 40: 432, pi. 19, fig. 1. 1912, 
 
 Colonies small, spherical, ovoid, or irregular ; with the cells enclosed 
 by a gelatinous, homogeneous, hyaline or ochraceous envelope. Indi- 
 vidual sheaths of cells confluent with colonial envelope. Cells spheri- 
 cal, fairly close together. Cell contents homogeneous, grey to pale 
 blue-green. (Euplanktont) . 
 
 Diam. cells 1. 6-2.0 [x. Colonies up to 75 /a broad and 100 fi long. 
 
 Birch Island (rr), Crawling Stone (rrr), Deer (ss), Lindy (r), Nancy (r), 
 Pine Tree (ss), Silver (2) (rr). 
 
 var. planctonica var. nov. PI. 3, Pig. 3. 
 
 Cells spherical, some distance from one another. Sheath enclosing 
 colony always hyaline. Contents of cells pale grey. (Euplanktont). 
 
 Diam. cells 2-3 fx. 
 
 Bear (1) (s). Bear Trap (rr), Poplar (ss). Round (3) (rr). Sand (1) (r). 
 
 Differing from the typical form in the larger cell size and grey color 
 of the cell contents. 
 
 Aphanocapsa endophytica sp. nov. PI. 2, Pig. 10. 
 
 Colonies endophytic within the gelatinous sheath of Microcystis col- 
 onies and with their envelopes confluent with the envelope of the host 
 colony. Cells spherical, equidistant from one another or in small 
 clumps. Cell contents homogeneous, grey to bright blue-green. (Eu- 
 planktont). 
 
 Diam. cells 2 jx. 
 
 Poor Farm (ss). 
 
 The occurrence of bacteria in the gelatinous envelope of colonial 
 Myxophyceae is a familiar phenomenon to the limnologist. The blue- 
 green color of the cells endophytic within the envelopes of Microcystis 
 colonies in Poor Farm Lake precludes their recognition as bacteria. 
 (See G. S. West’s remarks concerning a similar endophytic Aphano- 
 thece in Jour. Linn. Soc. Bot. 40: 432. 1912). 
 
 Aphanocapsa pulchra (Kiitzing) Rabenhorst. PI. 2, Pig. 9. 
 
 Flora Eur. Algarum 2: 49. 1865. 
 
 Colonics macroscopic or microscopic, free-floating or sessile, generally 
 spherical to ovoid when found in the plankton. Sheath of colony gela- 
 tinous, firm, hyaline, homogeneous; with the cells some distance from 
 
WISCONSIN PHYTOPLANKTON 
 
 43 
 
 one another. Individual cell sheaths confluent with the colonial en- 
 velope. Cell contents homogeneous, grey to pale blue-green. (Tycho- 
 planktont) . 
 
 Diam. cells 3. 5-4.5 jx. 
 
 Beaver (r), Beaverdam (sss), Harris (rrr), Lac Court Oreilles (ss), Win- 
 nebago (rr). 
 
 Aphanocapsa grevillei (Hassall) Kabenhorst. PI. 3, Fig. 1. 
 
 Flora Eur. Algarum 2: 50. 1865; G. S. West, Brit. Freshw. Algae, 351, -fig- 
 
 165^. 1904. 
 
 Colonies free-floating or sessile ; spherical to ellipsoid when free-float- 
 ing, dirty green in color. Cells spherical, solitary or in pairs and some- 
 what crowded. Cell contents homogeneous or finely granulose, bright 
 blue-green in color. (Facultative Planktont). 
 
 Diam. cells 3.5-5 ix, 
 
 Beaverdam (rr), Birch (ss), Camp (ss), Chetac (sss), Muskallonge (rr). 
 Rice (1) (rr). Silver (1) (rrr), Whitefish (ss). 
 
 Aphanocapsa rivularis ( Carm. ) Rabenhorst. PI. 3, Fig. 2. 
 
 Flora Eur. Algarum 2: 49. 1865; Cooke, Brit. Freshw. Algae 210, pi. 86, fig. 2. 
 1884. 
 
 Colonies free-floating or sessile; spherical, tubular, or irregular in 
 shape. Cells spherical, solitary or in pairs and some distance from one 
 another within the colony. Individual sheaths of cells confluent with 
 the hyaline, homogeneous, colonial envelope. Cell contents homogene- 
 ous or finely granulose; bright blue-green in color. (Tychoplanktont). 
 
 Diam. cells 5-6 ju. 
 
 star (rrr). 
 
 APHANOTHECE Nageli 1849. 
 
 Colonies free-floating, sessile, or endophytic; spherical or expanded 
 into amorphous masses and enclosed by a firm, copious, homogeneous, 
 hyaline or colored envelope. Cells oblong to cylindrical, with rounded 
 ends. Cells forming a solid mass distributed throughout the colonial 
 envelope but lying some distance from one another. Individual cell 
 sheaths indistinct, confluent with the colonial envelope. Cell contents 
 homogeneous or finely granulose, never with pseudovacuoles ; grey, light 
 to bright blue-green, or olive-green in color. 
 
 Reproduction by vegetative division of cells in three planes, but with 
 cell divisions always taking place at right angles to the long axes of 
 cells. 
 
44 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Colonies endophytic in gelatinous envelope of other algae. . 
 
 A. Nidulans V. Endophytica 
 
 Colonies not endophytic. 
 
 Cell contents grey to pale blue-green, never bright blue-green. 
 
 Colonies ovoid to spherical, never perforate A. Nidulans 
 
 Colonies reticulate to clathrate A. Clathrata 
 
 Cell contents bright blue-green. 
 
 Cells less than 5 fx broad A. Staqnina 
 
 Cells more than 5 /u broad A. Pbasina 
 
 Aphanothece clathrata W. & G. S. West. PI. 6, Fig. 3. 
 
 Trans. Roy. Irish Acad. 32, Sec. B: 111, pi. 10, /iffs. 9-11. 1906. 
 
 Colonies microscopic; free-floating; elongate and irregular in shape, 
 usually perforate and reticulate. Gelatinous colonial envelope hyaline 
 and homogeneous. Cells very small, bacilliform, straight or curved, 
 embedded in a solid mass in the colonial envelope. Cell contents homo- 
 geneous, grey to light blue-green. (Euplanktont). 
 
 Cells 0.6-1.0 fx broad, S.5-4.5 fx long. 
 
 Lindy (r). Little Crooked (sss), Nancy (ss), Pokegama (1) (r), Poor 
 Farm (rr). Sand (1) (ss), Wolf (ss). 
 
 Aphanothece nidulans P. Richter. PI. 6, Fig. 1. 
 
 Bot. Not. 1884: 128. 1884. 
 
 Colonies spherical, ovoid, or ‘‘nest-shaped^^; enclosed by a homogene- 
 ous, hyaline, gelatinous envelope. Cells broadly cylindrical, straight 
 or curved, of small size and fairly close together. Individual sheaths 
 of cells confluent with the colonial envelope. Cell contents homogene- 
 ous, grey to light blue-green. (Facultative Planktont). 
 
 Cells 1. 0-1.5 fx broad, up to 3.5 [x long. 
 
 Beaver (2) (ss). Deer (ss). Lower McKenzie (sss), Pokegama (sss). Ten- 
 derfoot (r). 
 
 Certain species of this genus resemble bacterial colonies in much the 
 same manner as the minute-celled species of Aphanooapsa. Here again 
 the color of the cell contents is good evidence of the algal nature of the 
 organism. 
 
 var. endophytica W. & G. S. West. PI. 5, Fig. 6. 
 
 Jour. Linn. Soc. Bot. 40: 432, pi. 19, fig. 14. 1912. 
 
 Cells embedded in gelatinous envelope of other colonial Myxophy- 
 ceae. Gelatinous envelope of colony confluent with envelope of host 
 
WISCONSIN PHYTOPLANKTON 
 
 45 
 
 colony. Cells narrow, at least twice as long as they are broad. Cell 
 contents homogeneous; generally light blue-green, rarely grey. (Eu- 
 planktont). 
 
 Cells 0.8-1.5 fi broad, 2.5-4.5 fi long. 
 
 Endophytic in sheaths of Coelosphaerium Kuetzingianum and Micro- 
 Cystis aeruginosa, 
 
 Birch Island (r), Chetac (ss), Hound (3) (rr). 
 
 Aphanothece prasina a. Braun. PI. 5, Fig. 5. 
 
 In Rabenhorst, Flora Eur. Algarum 2: 65. 1865; Cooke, Brit. Fresh w. Algae, 
 218, vl. 88, Ms. 3a-3b. 1884. 
 
 Colonies spherical to cylindrical, reaching a diameter of 3-4 cm. un- 
 der favorable conditions; bright green in color. Cells evenly dis- 
 tributed throughout the colony, broadly cylindrical and with rounded 
 ends. Individual cell sheaths confluent with the colonial envelope. 
 Cell contents homogeneous, bright blue-green. (Tychoplanktont). 
 
 Cells 5-6.5 broad, 7.7-11 /a long. 
 
 Beaverdam (r), Nancy (rr), Pokegama (1) (rrr). 
 
 The determination of this and the following species is open to ques- 
 tion since specific differences in these species are based in part upon 
 the macroscopic appearance of the colony when growing attached to 
 the substratum. The determination of plankton species is from imma- 
 ture colonies and must rest upon cell shape, size, and color. 
 
 Aphanothece stagnina (Sprengel) A. Braun. PI. 6, Fig. 2. 
 
 in Rabenhorst, Algen No. 1572; Cooke, Brit. Fresh w. Algae 219, pZ. 88, 
 fig. 4. 1884. 
 
 Colony spherical, ellipsoidal, or cylindrical; generally macroscopic, 
 0.5-20 mm in diameter, pale verdigris-green. Cells broadly cylindrical, 
 their length never more than II /2 times their breadth. Individual 
 sheaths of cells confluent with the hyaline, homogeneous, gelatinous, 
 colonial envelope. Cell contents homogeneous; pale to bright blue- 
 green. ( Tychoplanktont) . 
 
 Cells 3-5 p, broad ; 5-8 fx long. 
 
 Lake of the Woods (rr), Whitefish (rr). 
 
 GLOEOTHECE Nageli 1849. 
 
 Colonies free-floating or sessile, of comparatively few cells enclosed 
 by a hyaline or variously colored, homogeneous, gelatinous envelope. 
 Individual sheaths of cells prominent, homogeneous or slightly lamel- 
 
46 
 
 WISCONSIN PHYTOPLANKTON 
 
 lated, sometimes 2-8 cells enclosed by a single sheath. Cells elongate 
 to broadly cylindrical, with rounded ends and irregularly distributed 
 throughout the colonial envelope or with their longer axes pointing in 
 the same general direction. Cell contents homogeneous or finely granu- 
 lose ; grey, pale to bright blue-green, or olive green in color. 
 
 Keproduction by vegetative division of cells at right angles to their 
 long axes. 
 
 Gloeothece linearis Nageli. PI. 6, Fig. 5. 
 
 Gatt. einz. Algen 58, pi. 1, fig. G*. 1849. 
 
 Colonies small; dull yellow to flesh color or dirty olive-green; en- 
 closed by a broad, hyaline, homogeneous, gelatinous envelope. Cells 
 elongate-cylindrical, straight or arcuate, with rounded ends. Sheaths 
 containing one cell only, broad, hyaline, having the same general out- 
 line as the cell. Cell contents homogeneous ; pale to bright blue-green. 
 (Tychoplanktont) . 
 
 Cells (without sheath) 1.3-2. 5 /a broad, 10.5-18 (x long; (with sheath) 
 4r-6 fi broad, 13-22 jx long. 
 
 Harris (r), Muskallonge (rr). 
 
 var. composita var. nov. PI. 6, Fig. 6. 
 
 Cells shorter and 2-8 enclosed by a single, broad, firm, homogeneous 
 sheath. Individual sheaths of single cells or groups of cells not con- 
 fluent with the colonial envelope. (Tychoplanktont). 
 
 Cells (without sheath) 3.0-3.5 fx broad, 4-8 fx long; sheaths 10-12 
 fx broad, 20-35 fx long. 
 
 Deer (rrr). 
 
 RHABDODERMA Schmidle and Lauterborn. 1900. 
 
 Colonies free-floating, small, of comparatively few cells enclosed by a 
 hyaline, homogeneous, gelatinous envelope. Cells cylindrical, with 
 rounded apices, straight or arcuate; with their long axes pointing in 
 the same general direction. Individual sheaths of cells confluent with 
 colonial envelope. Cell contents homogeneous; grey to bright blue- 
 green in color. 
 
 Reproduction by vegetative division of cells, the divisions taking 
 place at right angles to the long axes of the cells. 
 
WISCONSIN PHYTOPLANKTON 
 
 47 
 
 Ehabdoderma lineare Schmidle and Lauterborn. PI. 6, Fig. 4. 
 Ber. d. D. Bot. Ges. 18: 148, pi. 6, figs. 8-11. 1900. 
 
 Specific characters as those of the genns. (Euplanktont). 
 
 Cells 2-3 IX broad, 6-12 [x long. 
 
 Sand (2) (rrr), Whitefish (rr). 
 
 This genus is closely related to Gloeothece, the chief difference being 
 a lack of individual sheaths around the cells. 
 
 DACTYLOCOCCOPSIS Hansgirg 1888. 
 
 Colonies microscopic, free-floating or lying among other algae; em- 
 bedded in a copious, hyaline, homogeneous, acicular to fusiform, gela- 
 tinous envelope. Cells elongate, acicular and with pointed ends; 
 straight arcuate, sigmoid, or spirally twisted around one another. In- 
 dividual cell sheaths confluent with colonial envelope. Cell contents 
 homogeneous or with the color bearing area localized in a definite part 
 of the cell ; grey to bright blue-green in color. 
 
 Reproduction by vegetative division of cells at right angles to their 
 long axes. 
 
 KEY TO THE SPECIES. 
 
 Length of cells never more than sixteen times the breadth, 
 
 cells frequently bent D. Raphidioides 
 
 Length of cells at least twenty times the breadth, cells al- 
 ways straight D. Acicularis 
 
 Dactylococcopsis rhaphidioides Hansgirg. PI. 6, Pig. 7. 
 
 Prodr. d. Algenfl. v. Bohmen 139, fig. 49a. 1892; Lemmermann, Kryptogamenfl. 
 
 d. Mark Brandenburg 3, Algen 1: 50. 1907. 
 
 Colonies containing 2-8 or more cells. Cells fusiform ; straight, arcu- 
 ate or sigmoid ; frequently in pairs with one end rounded and the other 
 pointed. Colonies enclosed by a copious, hyaline, homogeneous en- 
 velope. Cell contents homogeneous, pale blue-green. (Facultative 
 Planktont) . 
 
 Cells 1-3 IX broad, 5-25 ix long. 
 
 Deer (sss). Long (2) (rrr), Mercer (rr), Reserve (rr). Rice (1) (rr). 
 
 Hansgirg gives eight as the maximal number of cells found in the 
 colony but I have observed colonies in which there are as many as a 
 
48 
 
 WISCONSIN PHYTOPLANKTON 
 
 hundred cells. These cells are also proportionally longer than he statei 
 and may be, in extreme cases, sixteen times as long as they are broad. 
 In this respect they follow the cell dimensions delimited ,by Lemmer- 
 mann. 
 
 Dactylococcopsis acicularis Lemmermann. PI. 6 , Figs. 8 - 10 . 
 
 Ber. d. D. Bot. Ges. 18: 309. 1900; Kryptogamenfl. d. Mark Brandenburg 3, 
 Algen 1: 51, 44, iig. 5. 1907. 
 
 Cells solitary or in colonies enclosed by a wide, hyaline, homogeneous, 
 gelatinous sheath. Cells elongate, acicular, with poles attenuated to 
 fine points; straight or slightly arcuate. Cell contents homogeneous 
 and pale blue-green ; or with color bearing region restricted to one side 
 of cell. (Euplanktont). 
 
 Cells 2-2.5 fi broad, 55-80 /x long. 
 
 Browns (cc). 
 
 The localization of the color bearing portion at one side of the cell is 
 quite abnormal for a member of the Myxophyceae, but, as I have stated 
 elsewhere (Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 620. 1918) not- 
 withstanding this fact the alga belongs to the Myxophyceae. 
 
 Order HORMOGONEALES. 
 
 Cells always in filaments that generally contain a number of cells. 
 Filaments simple or branched ; solitary or united to form definitely or 
 indefinitely shaped aggregates. Free-floating, sessile, epiphytic, or en- 
 dophytic. Cells serially arranged to form trichomes, which when en- 
 closed by a sheath are known as filaments. Trichomes either the same 
 thickness throughout, attenuated towards both extremities, or attenu- 
 ated from base to apex ; straight, arcuate, spirally or irregularly twisted. 
 Sheaths of filaments tough and leathery; or gelatinous, homogeneous 
 to lamellated, hyaline to variously colored, and distinct or confluent 
 with the colonial envelope. Cell shape various. Cell contents homo- 
 geneous, or with numerous pseudovacuoles; grey, light to dark blue- 
 green, olive-green, reddish-green, ochraceo.us, orange, violet, or black 
 in color. 
 
 Reproduction, aside from vegetative cell division, by hormogones and 
 resting spores. 
 
WISCONSIN PHYTOPLANKTON 
 
 49 
 
 KEY TO THE FAMILIES. 
 
 Trichomes without heterocysts* Osciuatobiaceae 
 
 Trichomes with heterocysts. 
 
 Trichomes not attenuated Nostocaceae 
 
 Trichomes attenuated to a hair-like point Kivulariaceae 
 
 Family OSCILLATORIACEAE. 
 
 Trichomes free-floating, sessile, epiphytic, or endophytic; of one or 
 mere cells forming simple or branched filaments with one or more tri- 
 chomes within a single sheath. Sheaths of various forms; copious, 
 gelatinous, hyaline or colored, homogeneous to lamellated; firm, nar- 
 row and homogeneous or lamellated; or entirely lacking. Filaments 
 straight or spirally twisted. Cells disciform, cylindrical, or barrel- 
 shaped. Apical cell of trichomes frequently conical and capitate. 
 Heterocysts never present in the trichomes. Cell contents homogene- 
 ous, granulose, or with pseudovacuoles ; variously colored. 
 
 Reproduction by vegetative division of cells and the formation of 
 liormogones. 
 
 KEY TO THE GENERA. 
 
 Trichomes solitary or in flocculent, readily dissociating masses. 
 
 Trichomes containing but one cell Spiruuna 
 
 Trichomes containing more than one cell. 
 
 Sheaths of filaments firm, generally projecting beyond 
 
 the trichome Lyngbya 
 
 Sheaths delicate or lacking, not projecting beyond 
 
 trichome Oscillatoria 
 
 Trichomes laterally united to form free-floating bundles which 
 
 do not dissociate readily Trichodesmiiim 
 
 SPIRULINA Turpin 1827. 
 
 Trichome consisting of a single, elongate, cylindrical cell that is not 
 attenuated but with rounded ends. Filaments without sheaths and 
 twisted to form loose or compact regular spirals. Cell contents homo- 
 geneous or granulose ; light to dark blue-green in color. 
 
 Reproduction by vegetative division of cells at right angles to the 
 long axis. No hormogone formation possible. 
 
 *Cells commonly larger than the vegetative cells and with heavy walls that 
 have a conspicuous nodule at each pole. Cell contents a homogeneous, pellucid, 
 non-cytoplasmic substance. 
 
 4 
 
50 
 
 WI8C02^SIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Turns of spirals not over 5 fji in diameter S. Majob 
 
 Turns of spirals over 10 fx in diameter S. Pbinceps 
 
 Spirulina major Kiitzing. PI. 7, Fig. 1. 
 
 Phycol. generalis 183. 1843; Gomont, Ann. Sci. Nat. 7 Ser., Bot. 16: 251, pi. 7, 
 fig. 29. 1892. 
 
 Filaments free-floating and solitary, or forming a greenish scum. 
 Trichomes in a more or less loose spiral that is straight or bent. Cell 
 contents homogeneous ; bright blue-green. Sheath of filament lacking. 
 ( Tychoplanktont) . 
 
 Trichomes 1.2-1. 7 fx in diameter. Spirals 2.5-4 p. broad, 2.7-5 
 fx betv/een turns. 
 
 White Ash (rrr). 
 
 Spirulina princeps (W. & G. S. West) G. S. West emend. PI. 7, Pig. 2. 
 
 Jour. Linn. Soc. Bot. 38: 179, pi. 9, fig. 5. 1907; W. & G. S. West, Trans. Linn. 
 Soc. Bot. 2 iSer., Bot. 6: 205. 1902. 
 
 Trichomes solitary, in loose spirals that may be straight or curved. 
 Ends of trichomes blunt or rounded. Cell contents homogeneous or 
 with a few scattered granules; bright blue-green. (Tychoplanktont). 
 
 Trichomes 3-5 fx broad. Spirals 8.8-16 [x broad, 9.5-12 fx between 
 turns. 
 
 Poor Farm (rrr). 
 
 OSCILLATORIA Vaucher 1803. 
 
 Trichomes possessing a peculiar power of spontaneous movement of 
 an oscillating, rolling, or gliding type; free-floating; solitary or in 
 flocculcnt masses ; sometimes forming strata in moist places. Trichomes 
 unbranched, cylindrical, entirely without or Avith barely perceptible 
 sheaths. Ends of trichomes straight, slightly attenuated, but never at- 
 tenuated to a point. Terminal cells rounded or ealyptrate. Cell shape 
 cylindrical to disciform. Cell contents usually homogeneous or granu- 
 lose, rarely with pseudovacuoles. Color of cells variable. 
 
 Reproduction by hormogones. 
 
WISCONSIN PHYTOPLANKTON 
 
 51 
 
 KEY TO THE SPECIES. 
 
 Apex of trichome gradually tapering 
 Apex of trichome not tapering 
 
 OsciLLATORiA PROLiFiCA (Greviile) Gomont. PI. 7, Figs. 3-5. 
 
 Ann. Sci. Nat. 7 Ser. Bot. 16: 205, pi. 6, fig. 8. 1892; Olive, Trans. Wis. Acad. 
 Sei., Arts, & Lett. 15": 124-134. 1905; Hyams and Richards, Technology Quart. 
 
 14: 302-310, figs. 1-8. 1901. 
 
 Filaments rarely solitary, generally irregularly matted to form free- 
 tioating flocculent masses. Plant masses blood-red to dirty purple, be- 
 coming lilac when dried. Trichomes straight, elongate, not constricted 
 at cross walls of cells, and slightly tapered at apex with the terminal 
 cell of mature trichomes obtuse-capitate. Cells cylindrical, slightly 
 longer than they are broad. Cell contents with numerous reddish 
 pseudovacuoles, sometimes with rows of granules at the cross walls. 
 (Euplanktont). 
 
 Cells 2.2-5 fx broad, 4-6 [x long. 
 
 Geneva (aa). Pine (1) (aa). 
 
 This species is closely related to 0. ruhescens D. C., but if GomonCs 
 monograph of the Oscillatoriaceae must be taken as the starting point 
 for nomenclature of the group the two are distinct. Both species are 
 peculiar in that they produce blooms in lakes at a time when the water 
 is very cold or covered with ice. The masses of filaments do not have 
 the usual yellowish-green color but are blood red to dirty purple and 
 the phenomenon is spoken of in Europe as ‘‘bloody’^ or ‘‘Burgundy” 
 bloom. 
 
 Olive has described the occurrence of such a bloom in Pine lake of 
 this state and discussed the literature of the subject. The alga also 
 appeared in profusion in Lake Geneva this (1918) spring at the time 
 w'hen the ice was beginning to disappear. It was not frozen in the ice 
 but grew luxuriantly in the water below the ice and gave a deep red- 
 dish color that was especially noticeable in the cracks between the ice. 
 The alga had not been noted in the lake before this time and its sporadic 
 appearance is quite like the sporadic appearance of 0. ruhescens in the 
 Swiss lakes. The excessive growth of 0. prolifica is not wholly corre- 
 lated with cold water since it has remained present throughout the 
 summer, but not in such quantities as early in the spring. This abund- 
 ant growth of the alga in the summer has also been noted in a Massa- 
 chusetts lake by Hyams and Richards and furnishes a physiological as 
 well as a morphological distinction between 0. prolifica and 0. ruhes- 
 cens. 
 
 O. Prolifica 
 . . .0. Tenuis 
 
52 
 
 WISCONSIN PHYTOPLANKTON 
 
 OsciLLATORiA TENUIS C. A. Agardh. PI. 7, Fig. 6. 
 
 Algarum decades 2: 25. 1813; Gomont, Ann. Sci. Nat. 7 S§r. Bot. 16: 220, 
 j)J. 7, iigs. 2-3. 1832. 
 
 Filaments solitary or in floceose masses that are pale blue-green in 
 color. Trichomes straight, slightly constricted at the cross walls. Termi- 
 nal cells the same diameter as those in the median portion of the trich- 
 ome, straight or curved; apical cells rounded but not capitate. Cell 
 shape disciform. Cell contents homogeneous except for a row of gran- 
 ules along the cross walls. (Tychoplanktont) . 
 
 Cells 4—10 broad, 2.6-5 long. 
 
 Monona (rr). 
 
 var. TERGESTiNA (Kutzing) Rabenhorst. PI. 7, Figs. 7-8. 
 
 Flora Eur. Algarum 2: 102. 1865. 
 
 Trichomes narrower than the foregoing. (Tychoplanktont). 
 
 Cells 4-6 fx broad. 
 
 Geneva (ss). 
 
 LYNGBYA C. A. Agardh. 1824. 
 
 Filaments solitary or interwoven to form floceose masses; free-float- 
 ing or in an expanded stratum. Sheaths of filaments narrow, firm, 
 hyaline or colored, homogeneous or lamellated, generally projecting 
 for some distance beyond the trichome. Filaments unbranched, cylin- 
 drical ; straight, flexed, or twisted into regular spirals. Triciiomes gen- 
 erally the same thickness throughout, rarely slightly attenuated at the 
 apices ; sometimes constricted at the cross walls. Apical cell with distal 
 end rounded or slightly capitate. Cell contents homogeneous, granu- 
 lose, or with numerous pseudovacuoles ; grey, pale to bright blue-green 
 or variously colored. 
 
 Reproduction by the formation of hormogones. 
 
 KEY TO THE SPECIES. 
 
 Filaments not over 4 /a in thickness, with pale hlue-green to grey cell contents. 
 
 Filaments straight L. Limnetica 
 
 Filaments in regularly coiled spirals L. Contorta 
 
 Filaments over 10 ti in diameter, contents deeply colored L. Bibgei 
 
 Lyngbya limnetica Lemmermann. PI. 7, Figs. 9-11. 
 
 Bot. Cent. 76: 154. 1898; Kryptogamenfl. d. Mark Brandenburg 3, Algen 1 : 
 135, 102, fig. 8. 1907. 
 
 Filaments free-floating, generally solitary ; straight or slightly flexed. 
 Trichomes not constricted at the cross walls. Apical cells the same 
 
WISCONSIN PHYTOPLANKTON 
 
 53 
 
 thickness as the other cells, with distal end rounded but not capitate. 
 Sheaths firm, hyaline, very narrow, extending for some distance beyond 
 the end of the trichome. Cells cylindrical, at least twice as long as 
 broad. Cell contents homogeneous; generally grey, rarely blue-green 
 in color. (Euplanktont). 
 
 Cells 1-1.5 fi broad, 3-8 /a long. 
 
 Bear (1) (c), Geneva (ss), Soft (rr), Upper Nashotah (rrr). 
 
 The length of the individual cells of Wisconsin specimens exceeds 
 that given by Lemmermann but it is very probable that I am dealing 
 with the same species that he names L. limnetica. Several plankton 
 “species’^ have been described which are closely related and it is very 
 probable that future investigations will show that all of these straight, 
 very narrow, colorless ‘‘species” should be included under one collect- 
 ive specific name. 
 
 Lyngbya contorta Lemmermann. PI. 7, Figs. 12-13. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon 6: 202, pi. 5, -figs. 10-13. 1898; G. S. 
 West Jour, of Bot. 47: 246, pi. 498, iigs. 5^-5g. 1909. 
 
 Filaments free-floating, solitary ; occasionally straight, generally 
 twisted to form regular, loose or compact spirals or helices. Sheaths 
 firm, very thin, extending for some distance beyond the trichomes. Trich- 
 omes the same thickness throughout, not constricted at the cross walls, 
 apical cells rounded but not capitate at the distal ends. Cell contents 
 homogeneous, grey to pale blue-green. (Euplanktont). 
 
 Cells 1.5-2 fi broad, 3-6 /a long. Spirals 15-20 /a broad, 6-14 fi be- 
 tween the turns. 
 
 Mendota (rr). Pine Tree (ss). Poor Farm (s). White Ash (cc). 
 
 The specific distinction of this species is based in large part upon the 
 spiral twisting of the filament. Since certain normally straight fila- 
 ments of other algae become spirally twisted under limnetic conditions 
 (vide W. & G. S. West, Proc. Roy. Soc. London Ser. B, 81: 169, fig. 1. 
 1909) the validity of spiral twisting as a specific character arises. 
 L. contorta was found in considerable quantity at different stations and 
 the vast majority of filaments were spirally twisted. On the other 
 hand numerous filaments with cells of the same size that showed no 
 signs of twisting were collected from other stations. I think that Lem- 
 mermann is correct in considering these distinct species and that the 
 spiral twisting of filaments in plankton species of the Myxophyceae is 
 a sufficiently constant character to warrant the establishment of species 
 in both this genus and Anahaena. 
 
54 
 
 WISCONSIN PHYTOPLANKTON 
 
 Lyngbya birgei G. M. Smith. PI. 7, Figs. 14-15. 
 
 Bull. Torr. Bot. Cl. 43: 482, pi. 26, -fig. 28. 1916. 
 
 Filaments free-floating, solitary, never forming floccose masses; 
 straight or slightly flexed. Sheaths firm, at times of considerable thick- 
 ness, hyaline, generally homogeneous, rarely lamellated, extending for 
 some distance beyond the trichome. Trichomes not attenuated at apices 
 and without constrictions at the cross walls. Terminal cells rounded 
 but not capitate at distal ends. Cell shape disciform. Cell contents 
 rarely homogeneous and with grey to olive green contents ; usually with 
 numerous pseudovacuoles. (Euplanktont). 
 
 Cells 18-23 fx. broad, 2-5.5 long. Sheaths .5-4 p. thick. 
 
 Balsam (rr). Bear Trap (cc). Big (cc). Deer (rrr), Elizabetti (ss), Fowler 
 (rrr). Half Moon (c), Kegonsa (aa). Lac la Belle (rr). Little Crooked (r), 
 Little Wood (rr), Loveless (rr). Lower Nashotah (rr), Mary (ss), Mendota 
 (cc), Mercer (rr), Monona (cc), Mudhen (rr), Nagawicka (rr), Oconomowoc 
 (rr). Pope (rrr). Round (3) (sss). Sand (1) (r). Spirit (sss), Squirrel (sss), 
 Upper Nashotah (cc). Upper Turtle (rr), V/apagossett (cc), Waubesa (cc), 
 Wolf (r). 
 
 This is undoubtedly the alga that Trelease (Trans. Wis. Acad. Sci., 
 Arts, & Lett. 7: 124, pi. 10, fig. 6. 1888) reported from Lake Mendota 
 as Lyngbya Wollei Farlow. L. Viollei has been shown to be a Fleet o- 
 nema (P. Wollei Farlow) and Trelease ’s determination is undoubtedly 
 a mistake. 
 
 TRICHODESMIUM Ehrenberg 1830. 
 
 Trichomes laterally joined to form spindle- to scale-shaped, free- 
 floating colonies that are not enclosed by a gelatinous sheath. Trichomes 
 cylindrical, straight or spirally twisted, of the same thickness through- 
 out or with apices slightly attenuated. Apical cell undifferentiated, 
 or rounded and slightly capitate. Sheaths of trichomes very delicate. 
 Cells disciform to barrel-shaped. Cell contents homogeneous, granu- 
 lose, or with numerous pseudovacuoles. Heterocysts and resting spores 
 lacking. 
 
 Reproduction by the formation of hormogones. 
 
 i RicHODESMiUM LACUSTRE Klebahn. PI. 8, Pig. 1. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon 3: 13. 1895; Flora 80 : 271, pi. 4, iigs. 
 31-33. 1895. 
 
 Trichomes laterally joined to form plate-like, free-floating masses 
 that are not enclosed by a gelatinous envelope. Filaments with a very 
 delicate, homogeneous sheath. Trichomes straight, not attenuated at 
 the apices, and with terminal cells rounded but not capitate. Cells 
 
WISCONSIN PHYTOPLANKTON 
 
 55 
 
 disciform, with straight or markedly convex sides. Cell contents occa- 
 sionally homogeneons and pale to bright bine-green in color ; generally 
 with numerous pseudovacuoles. Trichomes without heterocysts or 
 spores. (Euplanktont). 
 
 Cells 5-7 II broad, 5-7 ix. long. Colonies up to 1 mm. in length. 
 
 Amicoy (rrr), Beaverdam (r), Island (rr), Lake of the Woods (rrr), Little 
 Bass (1) (rr),Mud (1) (s), Nicaboyne (rr),Bice (1) (rr),Wild Goose (rrr). 
 
 The general appearance of the colony at once suggests an ApJianizo- 
 menon species with cells shorter and more rounded than the familiar 
 A. flos-aquae. I have examined a sufficient number of colonies to feel 
 confident in confirming Klebahn’s statement that there are no spores 
 or heterocysts in the alga under consideration. This being the case it 
 is impossible to refer the species to AphanizomenoUj but it should be 
 considered a freshwater species of the common Tricliodesmium of tropi- 
 cal seas. 
 
 Family NOSTOCACEAE. 
 
 Filaments free-floating, sessile, epiphytic, or endophytic; solitary or 
 in colonies of microscopic to macroscopic size that are definitely or in- 
 definitely shaped. Trichomes always unbranched ; straight, flexed, spi- 
 rally twisted, or irregularly interwoven. Sheath rarely firm and nar- 
 row; generally copious, gelatinous, hyaline or colored, and distinct or 
 confluent with the colonial envelope. Trichomes generally the same 
 thickness throughout and with spherical to cylindrical cells. Hetero- 
 cysts either terminal or intercalary, solitary or catenate. Resting 
 spores variously shaped, adjacent to or remote from the heterocysts; 
 formed in all genera. Cell contents homogeneous, granulose, or with 
 pseudovacuoles ; grey or variously colored. 
 
 Reproduction by fragmentation of colony, hormogones, and resting 
 spores. 
 
 KEY TO THE GENERA. 
 
 Trichomes solitary or interwoven to form flocculent masses of 
 
 small size Anabaena 
 
 Trichomes laterally joined to form small plate-like colonies Aphanizomenon 
 
 ANABAENA Bory 1822. 
 
 Filaments free-floating or forming a delicate mucous layer; solitary 
 or in floccose colonies. Trichomes the same thickness throughout or 
 slightly attenuated at the apices; straight, spiral, circinate, or aggre- 
 gated without deflnite order. Sheaths delicate or copious, gelatinous, 
 hyaline, homogeneous, rarely confluent with the colonial envelope ; some- 
 
56 
 
 WISCONSIN PHYTOPLANKTON 
 
 times entirely lacking. Cells spherical to barrel-shaped, rarely cylindri- 
 cal, never disciform. Heterocysts approximately spherical, always in- 
 tercalary, generally solitary and with several in a filament. Spores 
 variously shaped, contiguous to or remote from heterocysts, solitary or 
 in short catenate series. Cell contents homogeneous, granulose, or with 
 numerous pseudovacuoles; grey, blue-green, or variously colored. 
 
 Reproduction by hormogones and spores. 
 
 KEY TO THE SPECIES. 
 
 Filaments straight or slightly curved. 
 
 Spores spherical A. Planctoxica 
 
 Spores longer than they are broad. 
 
 Length of spores not over twice their breadth. 
 
 Breadth of spores less than twice that of vegetative cells. 
 
 Spores oval to elliptic in optical cross section. 
 
 Vegetative cells less than 8 ^ broad A. Arrmis 
 
 Vegetative cells over 10 ii broad A. Limwetica 
 
 Spores hexagonal in optical cross section A. Macrospora 
 
 Breadth of spores more than twice the vegetative cells A. Levanderi 
 
 Length of spores at least three times their breadth A. Bori^etiana 
 
 Filaments spirally, circinately, or irregularly twisted. 
 
 Trichomes solitary, not forming floccose masses. 
 
 Curving of trichome a definite spiral A. Spiro ides 
 
 Curving of trichome not a definite spiral. 
 
 Length of spore at least four times breadth . . A. Augstumalis I. C. Marchia 
 
 Length of spore about twice the breadth A. Circinalis 
 
 Trichomes forming a fioccose mass. 
 
 Spores in a mass at center of colony A. Lemmermanni 
 
 Spores not in a mass at the center of the colony. 
 
 Trichomes loosely associated, individual filaments some- 
 times in spiral turns A. Circinalis 
 
 Trichomes greatly and irregularly twisted to form com- 
 pact masses A. Flos-Aquab 
 
 Anabaena planctonica Brunnthaler. PI. 8, Fig. 2. 
 
 Sitzenbr. d. kais. Ak. d. Wiss. Wien 112, Abt. 1; 292. 1903. 
 
 Filaments free-floating, solitary, straight, or slightly bent. Trichomes 
 enclosed by a copious, hyaline, very gelatinous sheath. Vegetative cells 
 spherical, hemispherical, or broadly elliptic. Heterocysts spherical. 
 Spores solitary, remote from or adjacent to heterocysts, spherical or 
 slightly elongate, somewhat broader than the vegetative cells. Cell con- 
 tents rarely homogeneous, usually with numerous pseudovacuoles. (Eu- 
 planktont). 
 
 Vegetative cells 9-15 fi broad; heterocysts 12-14 /a broad; spores 
 12.5-20 /X broad, 12.5-30 fx long. 
 
 Birch (1) (cc), Center (oc), Cranberry (cc). Devils (2) (ss), Rock (cc). 
 
WISCONSIN PHYTOPLANKTON 
 
 57 
 
 Many juvenile spores of other species are spherical but the spores of 
 this species never become appreciably elongated. 
 
 Anabaena affinis Lemmermann. PL 8, Fig. 7. 
 
 Abh. Nat. Ver. Bremen 14: 261, pi. 1, figs. 12-13, 16-17. 1897. 
 
 Filaments solitary, free-floating, straight or slightly flexed; with a 
 wide, homogeneous, hyaline, faintly discernible gelatinous envelope. 
 Mature vegetative cells generally spherical; rarely with homogeneous 
 contents, usually with pseudovacuoles. Heterocysts spherical. Spores 
 generally remote from heterocysts, short or elongate cylindrical, with 
 rounded ends and covered with a thick, smooth wall. (Facultative 
 planktont) . 
 
 Cells 5-6 /t broad ; heterocysts 7.5-10 (x broad ; spores 9.5-12 ix broad, 
 17-26 fx long. 
 
 Llndy (rr). Lost (rr). North Turtle (c), Pardee (sss), Poplar (ss). Sand 
 (1) (s). 
 
 Anabaena limnetica G. M. Smith. PI. 8, Fig. 8. 
 
 Bull. Torr. Bot. Cl. 43: 481, pi. 26, fig. 27. 1916. 
 
 Filaments free-floating, solitary, straight or slightly flexed; with a 
 copious, homogeneous, hyaline sheath. Vegetative cells spherical or 
 with poles flattened. Hdterocysts spherical. Spores smooth-walled, 
 solitary, broadly ovoid, remote from or adjacent to the heterocysts. Cell 
 contents rarely homogeneous, generally with numerous pseudovacuoles. 
 (Euplanktont). 
 
 Cells 12-15 fx broad ; heterocysts 10-14 fx broad; spores 17-20 fx broad, 
 20-30 fx long. 
 
 Bear Trap (ss), Birch (1) (cc). Soft (ss). Tamarack (cc). White Ash (ss). 
 
 Anabaena macrospora var. robust'a Lemmermann. PI. 8, Fig. 6. 
 Bot. Cent. 76: 154. 1898. 
 
 Filaments solitary, free-floating, straight or slightly bent, frequently 
 attaining a considerable length; with a copious, hyaline, homogeneous, 
 gelatinous envelope. Mature vegetative cells spherical or subspherical 
 with flattened ends. Heterocysts spherical. Spores solitary or in pairs, 
 adjacent to or remote from heterocysts, cylindrical with conical ends 
 and hexagonal in optical cross section. Spore wall smooth and thick. 
 Cells containing numerous pseudovacuoles. (Euplanktont). 
 
 Cells 12-16 fx broad, 9-12 ix long; heterocysts 12-16 fx broad; spores 
 17-19 /A broad, 30-34 fx long. 
 
 Camp (cc). Squirrel (ss). 
 
58 
 
 WISCONSIN PHYTOPLANKTON 
 
 Anabaena Levanderi Lenimermann. PI. 8, Figs. 4-5. 
 
 Ber. d. D. Bot. Ges. 24: 536. 1906. 
 
 Filaments solitary, free-floating, straight or slightly flexed, not en- 
 closed by a gelatinous sheath. Trichomes cylindrical, slightly con- 
 stricted at the cross walls of the cells. Vegetative cells twice as long as 
 they are broad, cylindrical, with rounded ends. Heterocysts hyaline, 
 spherical or ellipsoid. Spores solitary, adjacent to or remote from the 
 lieterocysts, twice as broad as the vegetative cells, ellipsoid in shape. 
 Cell contents rarely homogeneous and pale blue-green to grey ; usually 
 with numerous pseudovacuoles. (Euplanktont). 
 
 Cells 4-6 IX, broad, 11-33 [x, long ; heteroeysts 6.5-8 broad, 6. 5-9. 5 /a 
 long ; spores 8-15 /x broad, 19-45 fi long. 
 
 Chain (sss). 
 
 The dimensions of all specimens found in Chain lake have been near 
 the minimal limits set by Lemmermann. 
 
 Anabaena Bornetiana Collins. PI. 8, Fig, 3. 
 
 Erythrea4: 120. 1896. 
 
 Filaments free-floating, straight or slightly curved. Vegetative cells 
 spherical or slightly shorter than they are broad, with homogeneous 
 pale blue-green contents. Sheaths of trichomes very delicate. Hetero- 
 cysts spherical to elongate. Spores elongate cylindrical, with rounded 
 ends, adjacent to and on both sides of, or remote from the heterocysts. 
 
 ( Tychoplanktont) . 
 
 Vegetative cells 12 /x broad; heterocysts 13-14 /x broad, 13-20 (x. long; 
 spores 15-20 /x broad, 50-90 fx, long. 
 
 George (rr). 
 
 Only a few filaments of this species were found in George lake and 
 these contained but few spores which were not always adjacent to the 
 heterocysts. The species may, therefore, not be A. Bornetiana for Col- 
 lins states that the spores are always adjacent to the heterocysts. 
 
 Anabaena augstumalis var. marchica Lemmermann. PI. 8, Figs. 9-10. 
 Forschungsbr. a. d. Biol. Stat zu Plon 12: 147. 1905. 
 
 Filaments solitary, free-floating, more or less bent but not circinate, 
 without a gelatinous envelope. Vegetative cells spherical, broadly ellip- 
 soid or cylindrical ; with numerous pseudovacuoles. Heterocysts spheri- 
 cal or slightly elongate. Spores remote from heteroeysts, elongate cylin- 
 
WISCONSIN PHYTOPLANKTON 
 
 59 
 
 drical, with, rounded ends. Spore wail delicate, smooth, and hyaline. 
 (Facultative planktont). 
 
 Cells 5-7 fx broad, 5-9.5 fx long; heterocysts 8-9.5 /x broad, 8-14 tx 
 long; spores 9.5-12 jx broad, 40-70 /x long. 
 
 Bone (ss). Center (cc). 
 
 Anabaena spiroides var. crassa Lemmermann. PL 9, Figs. 1-3. 
 
 Bot. Cent. 76: 155. 1898; Kryptogamenfl. d. Mark. Brandenburg 3, Algen 1 : 
 
 ]88, 159, figs. 15-16. 1907. 
 
 Filaments solitary, free-floating; forming a regular, evenly spaced 
 spiral enclosed by a very transparent, homogeneous, gelatinous envelope. 
 Cells spherical or with flattened ends. Heterocysts spherical, hyaline 
 or pale yellow. Spores solitary, remote from the heterocysts, generally 
 broadly ovoid. Cell contents rarely homogeneous, usually with numer- 
 ous pseudovacuoles. (Euplanktont). 
 
 Cells 11-15 [X broad ; heterocysts 10-17 fx broad ; spores 20-25 [x broad, 
 27-42 (generally 27-31) /x long. Spirals 50-60 /x broad and 45-55 /x 
 between turns. 
 
 Big Butternut (cc), Big St. Germain (cc), Granite (cc). Hooker (c), Ke- 
 gonsa (a). Long (2) (sss), Little Butternut (cc), Mendota (cc), Monona (aa). 
 North Twin (sss). Round (3) (ss), South Turtle (c). Vermilion (ccc). 
 
 Anabaena circinalis (Kutzing)Eabenhorst. PI. 9, Figs. 4-5. 
 
 Algen No. 209. 1852; Phillips, Grevillea 9: 5, pi. 134, figs. e-g. 1880; Bornet 
 
 et Flahault, Ann. Sci. Nat. 7 Ser. Bot. 7: 230. 1888. 
 
 Anahaena Hassallii (Kiitzing) Wittrock. Bot. Not. 1882: 58. 1882. 
 
 Filaments free-floating, rarely solitary, curved or sigmoid; usually 
 greatly and irregularly twisted to form floccose masses. Filaments 
 v/ith or without a copious, hyaline, gelatinous envelope. Cells spheri- 
 cal or appreciably flattened at the poles, generally with numerous 
 pseudovacuoles. Heteroeysts spherical to subspherical. Spores usu- 
 ally remote from the heterocysts, cylindrical, with rounded ends when 
 mature, frequently curved and with smooth walls. (Euplanktont). 
 
 Cells 8-14 /X broad ; heterocysts 8-10 /x broad ; spores 16-18 /x broad, 
 26-30 /X long when mature. 
 
 Center (ss), Chain (sss). Lac la Belle (rr), Mercer (rr), Nagawicka (it). 
 Pike (r). Upper Nashotah (rr), Wapagossett (sss), Winnebago (ss). 
 
 This species differs from A. flos-aquae in the loose looping of the 
 trichomes, the larger vegetative cells and the broader spores. 
 
60 
 
 WISCONSIN PHYTOPLANKTON 
 
 var. MACROSPORA (Wittrock) de Toni. PI. 9, Fig. 6; PI. 10, Fig. 1. 
 Sylloge algarum 5: 445. 1907. 
 
 Anabaena Hassallii var. macrospora Wittrock, Bot. Not. 1882 : 59, figs. 7-9. 
 1882. 
 
 Vegetative cells somewhat smaller but with much narrower and pro- 
 portionally longer spores. 
 
 Cells 7-8 /X broad ; heterocysts 7.5-10 fx broad ; spores 9-10.5 p. broad, 
 28-42 (i long. 
 
 Camp (sss). 
 
 Anabaena flos-aquae (Lyngbye) de Brebisson. PI. 10, Figs. 2-4. 
 
 Mem. de la soc. Acad, de Falaise 1835: 36. 1836; Kiitzing, Tabulae Phycol. 1: 
 51, pi. 94, fig. 4. 1848; Bornet et Flahault, Ann. Sci. Nat. 7 Ser. Bot. 7; 228. 
 
 1888. 
 
 Filaments free-floating, densely coiled, irregularly twisted and inter- 
 woven to form a floccose colony. Cells spherical or cylindrical with 
 convex sides ; generally containing numerous pseudovacuoles. Hetero- 
 cysts broader and longer than the vegetative cells. Spores cylindrical, 
 with rounded ends, usually curved, solitary or in short catenulate 
 series ; generally adjacent to, rarely remote from the heterocysts. (Eu- 
 planktont) . 
 
 Vegetative cells 4-8 (generally 5.5) /x broad; heterocysts 6-9 /x broad; 
 spores 7-13 /x broad, 20-50 /x long. 
 
 Bear (1) (cc), Birch Island (r). Browns (cc). Camp (ss). Catfish (ss), 
 Catherine (rr), Cochrane (sss). Crab (r), Crawling Stone (rrr). Crooked (sss), 
 Des Moines (rr). Devils (1) (r). Eagle (sss), Fish (rr). Grassy (r). Green 
 (2) (sss). Half Moon (rr). Hooker (r). Horse (rrr), Jag (rr), Jennie (ss), 
 Kegonsa (rr). Lac Court Oreilles (ss). Lac la Belle (r). Little Crooked (rr), 
 Little Wood (r). Long (1) (rr). Long (3) (rr). Lower Nashotah (rr). Lynx 
 (sss), Mary (rr), Mendota (c), Mercer (rr). Mill (rr) Mud (2) (c), Nancy (s), 
 Oconomowoc (r), Okauchee (rr). Palmer (rr). Pine Tree (rr). Poplar (rr). 
 Round (1) (rr). Round (3) (r), Rudolph (rrr), Sanford (c). Shell (rrr), 
 Sishebogema (rr). South Crab (rr), Squirrel (rr). Upper Nashotah (r). Upper 
 Nemahbin (rr), Waubesa (c). Wildcat (sss). Wolf (r). 
 
 var. Treleasii Bornet et Flahault. PI. 10, Figs. 5-7. 
 
 Ann. Sci. Nat. 7 Ser. Bot. 7: 230. 1888. 
 
 Anahaena mendotae Trelease, Trans. Wis. Acad. Sci., Arts, & Lett. 7: 123, 
 pi. 10, fig. 5. 1889. 
 
 Cells smaller and with spores somewhat narrower and proportionally 
 longer. ( Euplanktont ) . 
 
 Vegetative cells 3-5 /x broad, 4.5-12 /x long; heterocysts 4.5-6 /x broad, 
 6-8 /X long ; spores 6-8 /x broad, 20-40 fx long. 
 
 Mendota (aa), Waubesa (s). 
 
WISCONSIN PHYTOPLANKTON 
 
 61 
 
 Anabaena Lemmermanni P. Richter. PI. 10, Fig. 8 ; PI. 11, Fig. 1. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon 10; 153. 1903. 
 
 Anabaena flos-aquae Klebahn non (Lyngbye) de Breb., Flora 80: 267, pi. 4 , 
 figs. 21-22. 1895. 
 
 Filaments free-floating ; irregularly or circinately interwoven to form 
 a spherical or broadly ellipsoid mass, with filaments frequently radiat- 
 ing in loops from a common center. Vegetative cells spherical or 
 slightly elongate, usually containing numerous pseudovacuoles. Heter- 
 ocysts spherical, approximately the same size as the vegetative cells. 
 Spores cylindrical, with rounded ends, with inner side straight and the 
 outer convex; rarely remote from heterocysts, generally forming short 
 catenate series on both sides of heterocysts and lying in a dense mass 
 at the center of the colony. The spore masses and heterocysts fre- 
 quently persisting long after the disappearance of the vegetative cells. 
 (Euplanktont). 
 
 Vegetative cells 5.5-7 /a broad, 5-8 long; heterocysts 6-7.5 /x broad; 
 spores 8-11 /x broad, 19-33 fx long. 
 
 Crawling Stone (rr), Diamond (r), Kawaguesaga (rr), Long (rr), Marl 
 (r), Oconomowoc (r), Paddock (cc), Palmer (r), Pardee (ss), Rainbow (2) 
 (rr), Reserve (r). Rice (1) (s),iSand (2) (rr), Taylor (ss), Trout (s). 
 
 The species differs from A. fios-aquae in the regular looping of the 
 trichomes from a common center and the development of a large mass 
 of spores at the center of the colony. The persistence of the spores 
 after the disappearance of the vegetative cells is very common and 
 certain of the records for the species are based upon observation of the 
 spore masses only. 
 
 APHANIZOMENON Morren 1838. 
 
 Trichomes straight slightly flexed, or curved ; in lateral contact with 
 one another to form small, macroscopic, free-floating, feathery, plate 
 or scale-like opaque colonies. Trichomes destitute of a gelatinous 
 sheath, sometimes constricted at cross walls of cells, and slightly attenu- 
 ated at the apices. Cells cylindrical, with flattened ends. Heterocysts 
 intercalary, cylindrical. Spores elongate, cylindrical and with flattened 
 ends; solitary, adjacent to or remote from the heterocysts. 
 
 Reproduction by the formation of hormogones and resting spores. 
 
 Aphanizomenon flos-aquae (L)Ralfs. PI. 11, Pigs. 2-4. 
 
 Ann. & Mag. of Nat. Hist. 2 Ser. 5: 340, pi. 9, fig. 6. 1850; Klebahn, Flora 80; 
 271, pi. 4, figs. 27-30. 1895. 
 
 Trichomes straight or slightly curved, laterally joined to form a flat 
 flake- or scale-like plate. Cells cylindrical, with flattened ends, about 
 
62 
 
 WISCONSIN PHYTOPLANKTON 
 
 three times as long as they are broad, generally with numerous pseudo- 
 vaeuoles. Heterocysts cylindrical, with straight or slightly convex sides, 
 without a distinct polar nodule. Spores elongate, cylindrical, with 
 rounded or somewhat flattened ends, generally some distance from the 
 heterocysts. ( Euplanktont ) . 
 
 Cells 4-6 IX broad, 5-15 fx long; heterocysts 5-7 ^x broad, 7-20 jx long; 
 spores 6-8 fx broad, 35-80 fx long. 
 
 Amicoy (aa), Balsam (ss), Bear (3) <rr), Beaverdam (rr), Big (r), Big 
 Butternut (rr), Birch (1) (c), Bone (rr), Camp (r), Catfish (sss), Center 
 (rrr), Chetac (aaa), Cranberry (ss). Crawling Stone (rrr), Deer (rrr), Dun- 
 ham (rr). Found (rr), Fowler (rr). Granite (a), Green (2) (ss). Half Moon 
 (sss), Hillman (sss). Hooker (cc). Horse (rrr). Horseshoe (1) (rr). Island 
 (c), Kawaguesaga (ccc), Kegonsa (cc). Lac la Belle (rr). Little Bass (2) (rr), 
 Little Butternut (s). Little Rice (1) (s). Little V/ood (rr). Long (3) (rr). 
 Lost (ss). Loveless (ss). Lower Nashotah (rr), Mendota (s), Mud (3) (rr), 
 Nagawicka (rr). North Twin (rrr), Oconomowoc (rr), Okauchee (rr), Pardee 
 (cc), Pewaukee (rr). Pike (rr). Plum (r), Pokegama (2) (rrr), Pokegama 
 
 (3) (aaa). Poplar (rrr). Prairie (aaa). Reserve (rr). Rice (1) (ss), Round 
 (1) (sss). Round (2) (ss), St. Croix (ccc). Sand (1) (r). Sand (3) (r). Sand 
 
 (4) (r), Sanford (sss), Shell (rrr). South Turtle (sss). Squirrel (a), Streitor 
 (rr), Tied Canoe (sss). Upper Nashotah (rr). Upper Nemahbin (r). Upper 
 Turtle (rr), Vermilion (r), Waubesa (s), White Ash (rr), Whitefish (rr). 
 White Sand (ss), Winnebago (r). 
 
 When the alga occurs in any quantity the lake appears to be fllled 
 with small pieces of macerated grass and it is one of the few plankton 
 genera that can be determined without the aid of a microscope. The 
 colony is so opague that the heterocysts cannot be seen while the colony 
 is intact but after a mount has been standing a few minutes the colonies 
 begin to dissociate into the component filaments and observation of the 
 heterocysts and spores is then an easy matter. The colonies are fre- 
 quently sterile and it is generally only during the colder months of the 
 year that there is a formation of spores. 
 
 Family ElVULARIACEAE. 
 
 Filaments rarely solitary, generally forming sessile or free-floating 
 spherical, hemispherical, or amorphous colonies. Trichomes gradually 
 attenuated from a broad basal cell to a hair-like apical cell. Sheaths 
 copious, homogeneous or lamellated, hyaline or colored, firm or gelat- 
 inous; enclosing one or more trichomes. Cells hemispherical, spheri- 
 cal, or disciform with convex sides at the basal portion of the triehome, 
 elongate cylindrical in the apical region. Cell contents variously col- 
 ored ; homogeneous, granulose, or with numerous pseudovacuoles. Trich- 
 omes simple or with “false branching’’. Heterocysts solitary; usually 
 
WISCONSIN PHYTOPLANKTON 
 
 63 
 
 at base of triehomes, rarely intercalary. Spores, when present, soli- 
 tary and adjacent to heterocysts. 
 
 E-eprodnction by formation of triehomes and spores. 
 
 GLOEOTRICHIA J. G. Agardh 1842. 
 
 Filaments always in colonies; free-floating or sessile; spherical to 
 hemispherical, tough and leathery to gelatinous, hyaline or colored. 
 Triehomes attenuated to fine hair-like processes at the distal end, en- 
 closed by gelatinous sheaths that are distinct at the base and confluent 
 at the apex. Filaments containing one triehome, but at times showing 
 false branching. Heterocysts spherical to hemispherical, solitary; at 
 the base of the triehomes. Spores cylindrical, solitary, always adjacent 
 to the heterocysts. Vegetative cells convexly disciform to short cylin- 
 drical at base of triehomes, elongate cylindrical with straight sides at 
 apex of triehomes. 
 
 Reproduction by hormogones and resting spores. 
 
 Gloeotrichia echinulata ( J. E. Smith) P. Richter. PI. 11, Pigs. 5-6. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon 2: 31, figs. 1-8. 1894. 
 
 Conferva echinulata J. E. Smith, Eng. Bot., pi. 1378. 1804. 
 
 Rivularia echinulata J. E. Smith, Eng. Bot. index; P. Richter, Forschungsbr. 
 a. d. Biol. Stat. zu Plbn 2: 45. 1894; Lemmermann, Kryptogamenfi. d. Mark 
 
 Brandenburg 3, Algen 1: 255, 245, figs. 1, 6. 1907. 
 
 Gloeotrichia pisum Bornet et Flahault (p.p.) non Thuret, Bull. Soc. Bot. 
 France 31: 80. 1884; Ann. Sci. Nat. 7 Ser. Bot. 4: 366. 1886; Trelease, Trans. 
 
 Wis. Acad. Sci., Arts, & Lett. 7 : 124-125 (with fig.) 1889. 
 
 Colonies always free-floating, spherical; up to 2 mm. in diameter. 
 Filaments radially arranged about a common center but becoming ir- 
 regular in arrangement on slight pressure. Sheaths hyaline, homogene- 
 ous, distinct at base, apex frequently confluent with colonial envelope. 
 Triehomes broad at base, attenuated to long, colorless, hair-like pro- 
 cesses. Lowest vegetative cell of triehome hemispherical ; those a short 
 distance from base disciform with markedly convex sides; those in 
 middle of triehome cylindrical ; while the cells in the apical region are 
 elongate cylindrical. Basal cells completely filled with cytoplasm, 
 apical cells with cytoplasm restricted to the median portion. Cell con- 
 tents rarely homogeneous, usually with numerous pseudovacuoles. 
 Heterocysts at base of triehome, spherical. Spores, when present, ad- 
 jacent to heterocysts, elongate cylindrical with rounded ends. 
 
 Cells at base of triehome 8-10 /x broad; at apex 1-2 fx broad; hetero- 
 cysts 7-10 fx broad ; spores 8-10 fx broad, 40-54 fx long. 
 
 Bass (3) (rr). Bear (3) (rr). Bear Trap (rr), Beaverdam (rr), Birch (2) 
 (ss), Birch Island (r), Bone (rr), Carroll (rr), Catherine (sss), Chetac (ss), 
 
64 
 
 WISCONSIN PHYTOPLANKTON 
 
 Clare (ss), Crawling Stone (rrr), Des Moines (cc), Diamond (ss), Duck (rr). 
 Dummy (rr), Dutchmans (ss), Fish (ss), Fowler (sss). Grindstone (rr). 
 Half Moon (ss). Horseshoe (1) (ss). Horseshoe (2) (rr), Howey (rr), Island 
 (ss), Jennie (rr), Kegonsa (aa), Kimball (rr), Lac Court Oreilles (ss). Lake 
 of the Woods (r), Lindy (rr), Long (1) (sss). Loon (r), Mendota (s), Monona 
 (cc), Nancy (ss). North Twin (r), Mercer (rrr). Middle McKenzie (ss), Mud 
 (3) (aa), Oconomowoc (rr), Owen (rrr), Razorback (aa). Reserve (rr), St. 
 Croix (rr). Sand (1) (rr). Sand (3) (rr). Shell (rr). Soft (rr). Trout (cc), 
 Waubesa (cc), Whitefish (sss). Wild Goose (rr), Winnebago (r). 
 
 A bloom of this alga can be recognized at once by the minute seed-like 
 colonies surrounded by an aureole of whitish threads. It was first 
 noted by Davis in England in 1804 and the plant figured and described 
 by Smith in his English Botany. The various references to the alga 
 before the recognition of a definite plankton flora have been compiled 
 by Bornet and Flahault as well as P. Richter. Since the study of the 
 plankton flora by phycologists the alga has been found in the lakes of 
 iQOst European countries. Although there seems to be but a single 
 species of the Rivulariaceae found free-floating in lakes and ponds the 
 nomenclatorial treatment of this species is quite varied. Bornet and 
 Flahault affirm that it is the common Gloeotrichia pisum, which ordi- 
 narily grows attached to submerged plants along the shore, that has 
 broken away and become free-floating. They hold that Rivularia 
 echinulata J. E. Smith (whose dimensions are the same as those of 
 G. pisum) is nothing but a free-floating G. pisum. In my observations 
 on the algae of our lakes there is no correlation between the appearance 
 of G. pisum and G. echinulata in the same lake in Wisconsin. In the 
 region of Madison, G. pisum does not appear until the middle of July 
 and yet at one time there was a heavy bloom of G. echinulata on the 
 28th of June, a time when there was no G. pisum along the shore. I 
 am convinced that the sessile Gloeotrichia is not the one found in the 
 plankton and that Richter is quite right in reviving the old specific 
 name echinulata. Some investigators hold that Gloeotrichia is but a 
 sub-genus of Rivuluria, but I have followed Bornet and Flahault in 
 considering the two distinct. This distinction is based upon the occur- 
 rence of spores in Gloeotrichia and a lack of spores in Rivularia. 
 
WISCONSIN PHYTOPLANKTON 
 
 65 
 
 Class PHAEOPHYCEAE. 
 
 Plants usually of macroscopic size and definitely shaped. Cells vari- 
 ously shaped and containing brown chromatophores in which a brown 
 pigment, phaeophycin, masks the chlorophyll. Cell wall not conspicu- 
 ously impregnated with silica and cells generally immobile in the vege- 
 tative phases. 
 
 Asexual reproduction by vegetative cell division, aplanospores, and 
 zoospores. 
 
 Sexual reproduction by isogamous zoogametes ; or heterogamous with 
 a fusion of zoogametes of unequal size, or a union of a large immobile 
 oosphere and a small motile antherozooid. 
 
 All of the complex non-motile members of this class are marine and 
 only unicellular or simple colonial forms are found in fresh waters. 
 These freshwater forms have the motile phase dominant, as a rule, and 
 form the subclass Chrysomonadineae of the Phaeophyceae. Many 
 place all of the colorless or brown chromatophored motile unicellular 
 organisms in a class by themselves, the Flagellatae, but, as I have stated 
 elsewhere, the group of the Chrysomonadineae seems sufficiently related 
 to the Phaeophyceae to warrant uniting the two. 
 
 Sub-class CHRYSOMONADINEAE. 
 
 Cells with one or more definite, disciform, laminate, or reticulate, 
 golden-brown chromatophores. Cells free-swimming or sessile, solitary 
 or in colonies of definite to indefinite shape. Life cycle generally with 
 the motile phase dominant but sometimes developing into amorphous or 
 rhizopodial palmella stages. Cells either naked or with a gelatinous 
 to definitely constituted periplast. Individual cells with 1-2 anterior 
 or lateral cilia of equal or unequal length; 1-10 contractile vacuoles, 
 generally at the anterior end; with or without an eyespot; and with 
 one or more chromatophores. Symmetry of cells bilateral, not inter- 
 rupted by a lateral or longitudinal grooving. Nutrition holophytic or 
 saprophytic ; assimilation product leucosin or fat, never starch. 
 
 Asexual reproduction by longitudinal or transverse division of cells. 
 Resting stages with heavy walls known in many genera. 
 
 Sexual reproduction as yet unknown in the sub-class. 
 
66 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE DIVISIONS. 
 
 Motile phase dominant, rhizopodial or palmella phase rare.EucHUYsoMONADiNAE 
 Immobile phase dominant, motile phase known or unknown. 
 
 Cells spherical to ovoid, embedded in a gelatinous envelope . . . Hydrurinae 
 Cells with pseudopodial processes Rhizochrysidinae 
 
 Division EUCHRYSOMONADINAE. 
 
 Cell structure and organization as noted in the description of the 
 sub-class. Ciliate phase dominating the life history. Palmella or 
 rhizopodial phases known but not the general rule. 
 
 KEY TO THE ORDERS. 
 
 Motile phase with one flagellum Chromulinales 
 
 Motile phase with two flagella. 
 
 Flagella of the same length Isochrysidaues 
 
 Flagella of unequal length Ochromonadales 
 
 Order CHROMULINALES. 
 
 Cells generally solitary, rarely colonial ; free-floating or sessile. ‘ Mo- 
 tile phase with a single apical flagellum. Chromatophores reticulate, 
 laminate, or disciform ; generally two in each cell. Apical contractile 
 vacuoles present or lacking. Cells either naked or with a deflnite, homo- 
 geneous or sculptured periplast. 
 
 Reproduction by vegetative division of cells. Thick-walled resting 
 stages known in certain genera. 
 
 KEY TO THE FAMILIES. 
 
 Cells naked Euohromtjlinaceae 
 
 Cells with a differentiated periplast Mallomonadaceae 
 
 Family EUCHROMULINACEAE. 
 
 Cells naked, without a differentiation of the periplast. Cells with 
 sharply defined disciform to laminate chromatophores, and without 
 contractile vacuoles. Flagellum single. 
 
 There are several genera with many species in the family but only 
 one of them, Chrysamoeha, has been noted in the plankton of the state. 
 
WISCONSIN PHYTOPLANKTON 
 
 67 
 
 CHRYSAMOEBA Klebs 1893. 
 
 Cells solitary, free-floating, with a mono-flagellate motile phase and 
 an amoeboid non-motile phase. Motile phase broadly ovoid, naked, 
 with two elongate, laminate, golden-brown chromatophores ; a large 
 non-contractile vacuole, 2-3 small contraetile vacuoles; and a single 
 flagellum slightly longer than the cell. Eye-spot lacking. 
 
 Non-motile phase solitary or in small clumps, with several simple or 
 branching pseudopodial processes extending in all directions. Chro- 
 matophores and vacuoles as in the motile phase. 
 
 Chrysamoeba radians Klebs. PI. 12 , Fig. 1 . 
 
 Zeits. f. wiss. Zool. 55: 406, pi. 18, iigs. la-lb, 1893. 
 
 Speciflc characters as described above. (Euplanktont). 
 
 Motile phase 8-10 /x, broad, 12-15 long; amoeboid phase (without 
 processes) 12-17 fx broad, (with processes) 35-40 p. broad. 
 
 Round (4) (rr), Taylor (rr). 
 
 Family MALLOMONADACEAE. 
 
 Cells always free-swimming, solitary or colonial, never metamorphos- 
 ing into a palmella or rhizopodial phase. Periplast of cells or colonial 
 envelope with numerous small plates of silica that have long, siliceous, 
 needle-like processes. Cells ovoid to ellipsoid, with one flagellum, a 
 number of contractile vacuoles and two long laminate chromatophores. 
 
 KEY TO THE GENERA. 
 
 Cells solitary Maixomonas 
 
 Cells in spherical colonies Chbysosphaebklla 
 
 MALLOMONAS Perty 1852. 
 
 Cells always solitary, free-swimming, with a single flagellum at the 
 anterior end. Periplast of cells with small circular or angular siliceous 
 discs covering the entire surface of the cell or restricted to one or both 
 ends. Scales frequently arranged in regular transverse or diagonal 
 rows, produced into a single, long, simple or toothed, needle-like setae. 
 Cells containing one or more contractile vacuoles that may be apical, 
 median, or basal in position. Chromatophores two, parietal, laminate, 
 and golden-brown in color. Assimilation product leucosin. 
 
 Reproduction by vegetative cell division parallel to the long axis. 
 Akinetes known in many species. 
 
68 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Setae restricted to one end of the cell. 
 
 Apical end with setae. 
 
 Cells cylindrical M. Alpina 
 
 Cells ovoid M. Tonsurata 
 
 Basal end with setae M. Producta 
 
 Setae covering whole cell M. Caudata 
 
 Mallomonas alpina Pascher & Kuttner. PI. 12, Fig. 4 . 
 
 in Pascher, D. Siisswasserfl. Deutschl., osterr., u. d. Schw. 2, Flagellatae 2: 36, 
 fig. 58a. 1913. 
 
 Cells ellipsoid to elongate cylindrical, with poles rounded or pointed. 
 Scales rhomboidal, in diagonal rows; with a single, long, straight or 
 curved seta. Setae confined to anterior end of cells. (Euplanktont). 
 Cells 8-12 broad, 25-45 long. 
 
 Camp (r). ‘ 
 
 Mallomonas producta (Zacharias) Iwanofi. PI. 12, Fig. 2. 
 
 Bull, de TAcad. Imp. d. Sc. de St. Petersbourg 5 Ser., 11: 250, pi. A, figs. 4-6. 
 1899. 
 
 Cells cylindrical, with straight or slightly convex sides, ends rounded 
 and tapering. Scales in regular transverse to diagonal rows, diamond- 
 shaped or laterally elongate. Setae straight or bent, confined to basal 
 portion of cell. Chromatophores two, golden-brown, laminate, and 
 parietal. (Euplanktont). 
 
 Cells 9-13 fi broad, 40-70 /x long. 
 
 Catfish (sss). Cranberry (ss), Crawling Stone (sss), Lac la Belle (ss). 
 Long (1) (ss), Otter (r). South Turtle (rrr), Upper Nashotah (rr). 
 
 var. MARCHiCA Lemmermann. PI. 12, Pig. 3. 
 
 Zeits. f. Fischeri 1903: 106. 1903. 
 
 Cells shorter and relatively broader. Setae sometimes at both ends 
 of cells. (Euplanktont). 
 
 Cells 11-12 fx broad, 21-26 jx long. 
 
 Nancy (r), Oconomowoc (ss), Tamarack (ss). 
 
 Mallomonas tonsurata Teiling. PI. 12, Fig. 5. 
 
 Sv. Bot. Tids. 6: 277, fig. 3. 1912. 
 
 Cells ellipsoid, with posterior end rounded and anterior end pointed. 
 Setae confined to anterior third of cell, fairly short and somewhat 
 curved. Scales not regularly arranged. (Euplanktont). 
 
 Cells 7-8 IX broad, about 18 /a long. 
 
 Waupaca (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 69 
 
 Mallomonas caudata Iwanoff. PI. 12, Fig. 6. 
 
 Bull, de I’Acad. Imp. d. Sc. de St. Pdtersbourg 5 Ser., 11: 250, PI. B, iigs. 1-8. 
 1899. 
 
 Cells broadly ovoid, with posterior end narrower than the anterior. 
 Scales oval, arranged in transverse series. Setae long, covering the 
 entire surface of the cell and frequently with minute teeth-like projec- 
 tions at the distal end. Cells with two long, parietal, laminate, chro- 
 inatophores. (Euplanktont). 
 
 Cells 12-30 fi broad, 40-85 long. 
 
 Beasley (rr), Birch (1) (rrr), Browns (rr), Carson (rrr), Catherine (rr), 
 Clare (r), Clear Crooked (rr), Crab (rr). Crawling Stone (rrr). Diamond 
 (rrr). Hill (ss), Jennie (rr). Kitten (sss). Lac la Belle (ss). Long (3) (ss), 
 Long (4) (rr). Lynx (rr). Mud (2) (ss). No Mans (s), North Turtle (r), 
 Okauchee (rr). Otter (sss), Pokegama (1) (rr), Pokegama (2) (r). Red Basa 
 (s), Rock (cc), Round (1) (sss), Rudolph (sss), St. Croix (rrr). Sand (4) 
 (sss), Sanford (sss). South Crab (rr). Wildcat (sss). Wild Goose (rr). Wolf 
 (rr). 
 
 CHRYSOSPHAERELLA Laut^rborn 1896. 
 
 Cells ellipsoid to pyriform, in spherical colonies of microscopic size 
 tliat are partially embedded in a spherical, hyaline, gelatinous envelope 
 containing numerous, tangentially placed, minute plates of silica. An- 
 terior ends of cells with two short, vase-shaped projections, each bear- 
 ing a single, long, straight, siliceous seta of some length. Cells with 
 one anterior flagellum ; two elongate, parietal, golden-brown chromato- 
 phores ; and several vacuoles. 
 
 Reproduction by vegetative cell division. Resting akinetes unknown. 
 
 Chrysosphaerella longispina Lauterborn. PI. 12, Figs. 7-8. 
 
 Zool. Anz. 19: 16. 1896; Zeits. f. wiss. Zool. 65: 381, pi. 18, figs. 12-16. 1899. 
 
 Speciflc characters as described above. (Euplanktont). 
 
 Average breadth of cells 9 /a, average length 15 fi. Colonies 50-250 /u 
 in. diam. 
 
 Bettine (rr), Blue Gill (ss), Boulder (rrr). Canteen (r), Elizabeth (rr). 
 Hill (aa). Lac la Belle (rr). Long (4) (rr), Lynx (r). Marl (rr), Mary (ss). 
 No Mans (rr), Oconomowoc (ss), Okauchee (s). Otter (ss). Rainbow (ss). 
 Round (4) (rr), Rudolph (sss), Silver (2) (ss). South Turtle (cc), Upper 
 Nemahbin (ss). Wild Goose (ccc). 
 
 Order ISO CHRYSID ALES. 
 
 Cells free-floating or sessile, solitary or colonial, naked or with a 
 definite homogeneous or sculptured periplast. Motile phase always 
 present, palmella or rhizopodial phase lacking. Cells variously shaped, 
 
70 
 
 WISCONSIN PHYTOPLANKTON 
 
 always with two apical cilia of equal length ; generally with two lami- 
 nate, parietal, golden-brown chromatophores and without an eyespot. 
 
 The only family represented in the flora of the state is that of the 
 Euhymenomonadaceae. 
 
 Family EV HYMEN OMON AD ACE AE. 
 
 Differing from other families of the order in having a definite sculp- 
 tured periplast and an anterior vacuolar system. Synura the sole 
 representative. 
 
 SYNURA Ehrenberg 1838. 
 
 Cells radially arranged in spherical to oblong-ovoid free-swimming 
 colonies that are not enclosed by a gelatinous sheath. Individual cells 
 broadly pyriform, with the narrower end towards the center of the 
 colony. Outer portion of cells firm, with small spines, reticulations, 
 or combinations of the two. Cells with two long anterior cilia of equal 
 length, several vacuoles, two long laminate parietal chromatophores, 
 and without an eyespot. 
 
 Reproduction by division of cells and liberation of cell contents to 
 form amoeboid cells. Akinete formation also known. 
 
 Synura uvella Ehrenberg. PI. 12, Figs. 9-10. 
 Infusionsthierchen 61, pi. 3, figs. 9^-9®. 1838. 
 
 Exterior of cells covered with fine spines that are generally limited 
 to the anterior portion. (Facultative Planktont). 
 
 Cells 8-17 broad, 20-35 fi broad. Colonies up to 350 /a in diam. 
 
 Camp (ss), Canteen (cc). Crawling Stone (rrr), Fowler (cc), Jenny (rr), 
 Kawaguesaga (rr), Little Bear (rrr). Little Crooked (rr). Long (3) (r), 
 Lower Nemahbin (rr). Lynx (r), Mendota (ss), Mercer (rr). Mill (ccc), Mud 
 (2) (rr), Nagawicka (cc), Nancy (cc), Nicaboyne (rr). No Mans (cc), North 
 Turtle (rr), Oconomowoc (s). Palmer (c), Pardee (sss), Pewaukee (sss), 
 Pope (rrr). Rainbow (1) (rr). Red Bass (ss). Round (1) (sss), Rudolph (sss). 
 Sand (4) (rr), Sanford (ss), South Turtle (rr). 
 
 Order OCHROMONADALES. 
 
 Cells solitary or colonial, free-swimming or sessile, not forming pal- 
 mella or rhizopodial stages. Cells naked, or with a definitely shaped re- 
 ceptacle ; two lateral or apical cilia of unequal length, one or two golden- 
 brown disciform to laminate chromatophores ; contractile vacuoles ; and 
 an eyespot. 
 
WISCONSIN PHYTOPLANKTON 
 
 71 
 
 KEY TO THE FAMILIES. 
 
 Cells naked, at times in a gelatinous envelope but never a 
 
 definite receptacle Ochbomonadageae 
 
 Cells within a definite receptacle Dinobryaceab 
 
 Family OCHROMONADACEAE. 
 
 Cells solitary or in colonies, always free-swimming, not enclosed by 
 a definite receptacle but at times with a hyaline, homogeneous, gelat- 
 inous envelope. Cells with two apical cilia of unequal length, one or 
 two golden-brown chromatophores, an eyespot and contractile vacuoles. 
 
 Uroglenopsis is the only representative in the local flora. 
 
 UROGLENOPSIS Lemmermann 1899. 
 
 Colonies free-swimming, with the cells embedded in a single layer at 
 the periphery of a copious, hyaline, homogeneous, gelatinous matrix of 
 spherical to broadly ellipsoid shape. Arrangement of cells radial or 
 somewhat irregular. Cells spherical to narrowly ellipsoid; with two 
 cilia of unequal length; two vacuoles at the anterior end; one or two 
 laminate to disciform, parietal, golden-brown chromatophores ; and with 
 or without an eyespot. 
 
 Reproduction by vegetative cell division. 
 
 Uroglenopsis Americana (Calkins) Lemmermann. PI. 13, Figs. 1-4. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plbn 7: 107. 1899; Kryptogamenfl. d. Mark 
 Brandenburg 3, Algen 1 : 449, 444, figs. 1-3, 4-6. 1908. 
 
 Vroglena americana Calkins, Ann. Kept. Mass. State. Bd. of Health 23 : 655, 
 Vl. 4, figs. 1-4. 1892; Moore, Bot. Gaz. 23; 105, pi. 10, figs. 1-11. 1897. 
 
 Colonies free-swimming, generally spherical. Cells ellipsoid, with 
 one basal or lateral, parietal, disciform to laminate chromatophore. Eye- 
 spot single. Cilia of unequal length, with the longer 2-3 times the 
 length of the cell, the shorter %-i/2 the length of the ceU. (Euplank- 
 tont). 
 
 Cells 3-7 [ 1 . broad, 5-10 long. Colonies up to 500 fi in diam. 
 
 Beasley (cc), Bettine (ss). Browns (ss), Camp (ss), Carson (rrr). Diamond 
 (rr). Eagle (sss), Fowler (cc), Howey (rr), Lac la Belle (ss). Long (3) (ss). 
 Long (4) (rr). Lower Nemahbin (rr), Lynx (rr), Mendota (ss). Mill (ss). 
 Mud (4) (cc), Nancy (rr), Oconomowoc (ss), Okauchee (rrr), Otter (ss), 
 Paddock (s), Pewaukee (rr). Rainbow (1) (ss). Round (4) (rr), Taylor (ss). 
 Wildcat (ss), Wolf (rr), Youngs (cc). 
 
72 
 
 WISCONSIN PHYTOPLANKTON 
 
 Family DINOBRYONACEAE. 
 
 Cells solitary or in colonies, free-floating or sessile. Always attached 
 to the base of a conical to vase-like, colored or hyaline, smooth or sculp- 
 tured receptacle. Cells with one or two laminate chromatophores, con- 
 tractile vacuoles, an eyespot, and two cilia of unequal length. 
 
 KEY TO THE GENERA. 
 
 Receptacles homogeneous, without growth rings Dinobryon 
 
 Receptacles with successive growth rings Hyalobryon 
 
 DINOBRYON Ehrenberg 1835. 
 
 Cells free-floating, sessile, or epiphytic; solitary or in colonies; at- 
 tached to the bottom of conical, campanulate, or cylindrical receptacles 
 with open apices and pointed bases. Colonial species arbuscular, each 
 receptacle with the pointed ends of 1-4 other receptacles in its mouth. 
 Development of branching indefinite. Protoplast spindle-shaped, coni- 
 cal, or ovoid ; attached by a stalk to the base of the receptacle. Anterior 
 end of protoplast with two cilia of unequal length that project beyond 
 the open end of the receptacle. Cells with one or two laminate, elon- 
 gate, parietal, golden-brown chromatophores; several apical, lateral, or 
 basal contractile vacuoles; and one apical eyespot. Assimilation pro- 
 duct generally leucosin. 
 
 Reproduction by longitudinal division of cell contents to form ovoid 
 daughter cells that migrate to the mouth of the old receptacle or leave 
 it entirely before developing new receptacles. Akinetes known. 
 
 The specific limits of colonial plankton species of this genus are very 
 poorly defined and it is almost impossible to draw a sharp line of de- 
 marcation between the various species. I have indicated as species the 
 centers around which the variations seem to occur. 
 
 KEY TO THE SPECIES. 
 
 Cells solitary. 
 
 Cell shape conical, elongate D. CAijoiFOBMa 
 
 Cells broadly spindle-shaped D. Tabellabiae 
 
 Cells in colonies. 
 
 Branching of cells markedly divergent D. Diveegens 
 
 Branching of cells not sharply divergent. 
 
 Cells elongate conical. 
 
 Sides of receptacles straight D. Stipitatum 
 
 Sides of receptacles undulate D. Bavaricum 
 
 Cells campanulate D. SEn'ULARiA 
 
WISCONSIN PHYTOPLANKTON 
 
 73 
 
 Dinobryon caliciforme Bachmann. PL 13, Figs. 5-6. 
 
 Arch. f. Hydrob. u. Planktonkde. 3: 82, fig. 1908. 
 
 Cells solitary; epiphytic upon the gelatinous envelope of various 
 colonial Myxophyceae. Receptacles elongate conical, with a sharply 
 pointed base. Protoplast the same shape as the lower two-thirds of re- 
 ceptacle. Chromatophores two, laminate, parietal, and golden-brown 
 in color, Eyespot single. Cilia not as long as the cell. (Euplank- 
 tont) . 
 
 Receptacles 5-6 fx broad at apex, 30^0 fx long. 
 
 Embedded in or on gelatinous envelope of Coelosphaerium Naegeli- 
 anum and Microcystis aeruginosa. 
 
 Browns (sss). 
 
 Dinobryon tabellariae (Lemmermann) Pascher. PL 13, Figs. 7-9. 
 
 Siisswasserfl. Deutschl., osterr. u. d. Schw. 2, Flagellatae 2: 66, figs. 105»-105b. 
 1913. 
 
 Dinobryon utriculus var. tabellariae Lemmermann, Arkiv for Botanik 2, 
 No. 2: 119, pi. 1, fig. 19. 1904. 
 
 Cells solitary; epiphytic upon filaments of Tahellana. Receptacle 
 broadly spindle-shaped, with the base produced into a short stipe. Pro- 
 toplast attached to side of lower portion of receptacle, ovoid in shape 
 and with the usual contents of the genus. (Euplanktont). 
 
 Receptacles 7-10 fx broad at center, 4-5 at apex ; 18-22 fx long. 
 
 Crawling .Stone (r). Long (3) (rr). Sand (4) (s). 
 
 Dinobryon bavaricum Imhof. PL 13, Fig. 10. 
 
 Zool. Anz. 13: 484. 1890; Lemmermann, Bot. Not. 1903 : 78, pi. 3, figs. 3-4. 
 1903. 
 
 Cells in free-floating compact colonies. Receptacles of individual 
 cells elongate-conical. Base of receptacle very much produced with 
 sides almost parallel; expanded portion of receptacle with undulate 
 sides. Seasonal variation pronounced, the receptacles being much 
 longer during the summer. (Euplanktont). 
 
 Receptacles 6.5-8. 5 fx broad ; 45-100 long. 
 
 George (ss), Harris (rr), Marl (ss), Oconomowoc (ss), Speese (ss), Tied 
 Canoe (ss). White Sand (s). 
 
74 
 
 WISCONSIN PHYTOPLANKTON 
 
 Dinobryon stipitatum Stein. PI. 13, Fig. 11. 
 
 Der Organismus der Infusionstiere 3: pi. 12, iig. 5. 1878; Pascher, D. Suss- 
 
 wagserfl. Deutschl. osterr. u. d. Schw. 2 , Flagellatae 2 : 73, -fig. 118. 1913. 
 
 Cells always in narrow, fairly dense, free-floating colonies. Recep- 
 tacles of individual cells elongate-conical, with bases produced into stipes 
 with nearly parallel sides. Sides of receptacle not undulate. Indi- 
 vidual receptacles of colony not divergent from one another. Seasonal 
 variation chiefly in elongation of apical cells of colony. (Facultative 
 Planktont) . 
 
 Receptacles 6-8 /a broad ; 56-96 fi long. 
 
 Marl (ss), Oconomowoc (cc). Round (4) (sss), iSouth Turtle (rr). 
 
 Dinobryon sociale Ehrenberg. PI. 13, Fig. 12. 
 
 Abh. d. k. Ak. d. Wiss. Berlin 1833; 279. 1835; Die Infusionsthiercben 125, 
 pi. 8, fig. 9. 1839; Pascher, Siisswasserfl. Deutschl. osterr. u. d. Schw. 2 , 
 
 Flagellatae 2: 73, figs. 116-117. 1913. 
 
 Cells in free-floating colonies. Individual receptacles somewhat di- 
 vergent from one another and producing a fairly loose colony. Recep- 
 tacles conical, sometimes slightly constricted below the open mouth, with 
 bases gradually tapering to a sharp point that is not extended to form 
 a process. (Facultative planktont). 
 
 Receptacles 7-8 /t broad, 30-70 fi long. 
 
 Beasley (ss), Green (1) (ss). Green (2) (cc), Mill (c). North Turtle (rr), 
 Oconomowoc (cc). Silver (2) (s). Trout (rr). 
 
 Dinobryon setularia Ehrenberg. PI. 13, Fig. 13; PI. 14, Fig. 1. 
 
 Abh. d. k. Ak. d. Wiss. Berlin 1833: 280. 1835; Die Infusionsthiercben 124, 
 pi. 8, fig. 8. 1838. 
 
 Cells in free-floating, densely branching colonies. Receptacles cylin- 
 drical-campanulate, with the convex bases tapering abruptly to a sharp 
 point. Cells with shorter and broader receptacles than the other species. 
 Seasonal variation not so pronounced as in other species. (Facultative 
 Planktont) . 
 
 Receptacles 10-14 ja broad, 30^4 fi long. 
 
 Devils (1) (ccc), Kawaguesaga (ss). Long (4) (ss). Lost (ss). Lower 
 Nemahbin (ss). Rock (ss), Round (3) (ss), Winnebago (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 75 
 
 Dinobryon divergens Imhof. PI. 14, Fig. 2. 
 
 Jahresbr. d. Naturf. Ges. Graubiindens N. P. 30: 134. 1887. 
 
 Dinotryon cylindricum var. divergens (Imhof) Lemmermann, Ber. d. D. Bot. 
 Ges. 18: 517, pZ. 19, /Zfirs. 15-20. 1900. 
 
 Cells in free-floating densely or openly branched colonies. Recep- 
 tacles with conical bases and the upper portion cylindrical or with 
 slightly flaring mouths. The axis of the upper portion of receptacle 
 forming an angle of 45—90 degrees with that of the basal portion. Sides 
 of receptacle sometimes undulate. Seasonal variation confined to dense- 
 ness of branching in colony rather than changes in receptacle shape. 
 (Facultative Planktont). 
 
 Receptacles 7-8 {x broad, 35-50 ix long (2(4-27 p, in upper portion and 
 15-20 in basal portion). 
 
 Beasley (s), Boulder (cc). Browns (cc), Center (ss). Devils (1) (ss), 
 Elizabeth (cc), George (r). Green (2) (rr). Hill (cc). Lac la Belle (ss), 
 Long (2) (rr). Marl (ss), Mary (cc), Meta (r). Mill (cc), Mud (1) (ss), 
 Nagawicka (cc). North Turtle (ss), Oconomowoc (cc). Otter (ss). Rock (ss). 
 Round (4) (rrr). Silver (2) (cc), Speese (cc), Tamarack (ss), Taylor (ss), 
 Tied Canoe (ss). 
 
 HYALOBRYON Lauterborn 1896. 
 
 Cells solitary or in branching colonies, free-floating or epiphytic. 
 Receptacle shape and cell contents as in Dinobryon but with the wall 
 of the receptacle containing a number of successive growth rings instead 
 of homogeneous. Wall of receptacle more delicate than Dmohryon. 
 
 Hyalobryon mucicola (Lemmermann) Pascher. PL 14, Figs. 3-4. 
 
 D. iSiisswasserfl. Deutschl., osterr. u. d. Schw. 2, Plagellatae 2: 81, fig. 131. 1913. 
 
 Hyalohryon Lauter'bornei var. mucicola Lemmermann, Ber. d. D. bot. Ges. 
 19: 340. 1901; Bachmann, Arch. f. Hydrob. u. Planktonkde. 8: 81, figs. XP*- 
 XI”. 1908. 
 
 Cells solitary, epiphytic upon gelatinous envelope of colonial Myxo- 
 phyceae, Chlorophyceae and Phaeophyceae. Receptacle delicate, upper 
 portion cylindrical and with a flaring mouth, lower portion conical and 
 with a short stipe. Growth rings of receptacle numerous. Protoplast 
 ovoid, attached to base of receptacle, with two golden-brown chromato- 
 phores, two cilia of unequal length and an eyespot. (Euplanktont). 
 Receptacles 4-6 ix broad, 25-45 fx long ; stipe 4-12 ix long. 
 
 Crawling Stone (r), Lac du Flambeau (sss), Long (3) (c), Mud (2) (rr), 
 Round (1) (rr). 
 
76 
 
 WISCONSIN PHYTOPLANKTON 
 
 Division HYDRURINEAE. 
 
 Cells free-floating or sessile, usually in palmella-like colonies and 
 motile only at the time of reproduction; rarely solitary, generally in 
 gelatinous colonies of microscopic to macroscopic size that have a 
 definite to indefinite shape. Colony capable of growth in all parts or 
 with growing region restricted to apex. Gelatinous sheath of cells hya- 
 line, homogeneous or lamellated. Cells ovoid to spherical, with one or 
 two golden-brown parietal chromatophores and with or without a 
 definite wall. 
 
 Reproduction by pyramidate, spherical, or ovoid zoospores with one 
 or two cilia. 
 
 The members of this division are the connection between the normally 
 motile and the highly differentiated sessile Phaeophyceae. 
 
 Order PHAEO CAPS ALES. 
 
 Cells generally organized into free-floating, spherical, ellipsoid, or 
 elongate colonies. Growth of colony taking place in all parts and not 
 restricted to the apical region. Cells variously shaped and with one or 
 two golden-brown chromatophores. 
 
 Reproduction, aside from vegetative cell division, by the formation 
 of spherical to ovoid zoospores. 
 
 The order contains the single family of the Phaeocapsaceae and only 
 one member of the family, Phaeococcus, is found in the local flora. 
 
 PHAEOCOCCUS Borzi 1892. 
 
 Cells in spherical, ovoid, or irregularly shaped free-floating colonies 
 enclosed by a copious, hyaline, homogeneous or slightly lamellated, 
 gelatinous envelope. Cells ellipsoid to sub-spherical or spherical. Cell 
 number a multiple of two in young colonies, indefinite in older colonies. 
 Cells containing one or more golden-brown chromatophores, sometimes 
 with a red pigment spot. 
 
 Reproduction by vegetative cell division or direct metamorphosis of 
 cell contents into biciliate ovoid to pyriform zoospores. 
 
 Phaeococcus planctonicus W. & G. S. West. PI. 14 , Fig. 6. 
 
 Trans. Roy. Soc. Edinb. 41; 496, pi. 6, figs. 15-16. 1905. 
 
 Cells spherical to sub-spherical, generally distributed in small clumps 
 within a copious, hyaline, homogeneous or radially fibrillar, gelatinous 
 envelope. Number of cells in colony generally 16-64. Cells contain- 
 
WISCONSIN PHYTOPLANKTON 
 
 'll 
 
 ing 1-2 parietal, disciform to bell-shaped, golden-brown chromatophores 
 with smooth or irregular margins. (Euplanktont). 
 
 Cells T.2-9.6 in diam. ; colonies 50-250 ft in diam. 
 
 Carson (ss), Clear Crooked (c), Crawling Stone (rr), Devils (1) (ss), Hill- 
 man (rr), Jennie (r), Mary (s), Mendota (sss), Pokegama (1) (rr), Sand 
 (4) (rr), Shell (ss), Silver (2) (s). White Sand (rr). 
 
 Division RHIZOCHRYSIDINAE. 
 
 Algae that are known in the rhizopodial stage only, although the 
 power to form a motile phase is presumed to be present. Cells solitary 
 or in small colonies, always free-floating. Cells with rhizopodial pro- 
 cesses and with or without a differentiated periplast. Cells with 1-2 
 golden-brown chromatophores, and with or without numerous vacuoles. 
 
 Reproduction by vegetative cell division. 
 
 This is an entirely artificial group where rhizopodial forms are placed 
 pending further elucidation of their life histories. Since the group 
 contains such doubtful forms no attempt has been made to differentiate 
 the orders and families. 
 
 KEY TO THE GENERA. 
 
 Cells solitary or in irregular colonies Rhizochrysis 
 
 Cells joined in a linear series to form colonies Chrysidastrum 
 
 RHIZOCHRYSIS Pascher 1913. 
 
 Cells free-floating, solitary or in colonies that are naked or enclosed 
 by a gelatinous sheath. Cells without a differentiation of the periplast 
 but with few or numerous, delicate, pseudopodial processes. Cells with 
 one or two golden-brown chromatophores and numerous vacuoles, of 
 small size when united in colonies. 
 
 Rhizochrysis limnetica sp. nov. PI. 14, Fig. 6. 
 
 Cells solitary, free-floating, without a differentiation of the periplast 
 but with numerous spicule-like processes extending in all directions. 
 Cells approximately spherical, with one golden-brown chromatophore 
 and numerous vacuoles. (Euplanktont). 
 
 Diam. cells (without processes) 35-45 ft. 
 
 Beasley (sss), Birch Island (rr), Crawling Stone (rr), Deer (rr), Diamond 
 (rrr), Half Moon (rr). Horse (rr), Kitten (sss), Lac du Flambeau (r). Long 
 (3) (sss). Marl (rrr), Nemahbin (ss), Oconomowoc (rr), Okauchee (rrr), 
 
78 
 
 WISCONSIN PHYTOPLANKTON 
 
 Otter (rrr), Pokegama (2) (r), Rainbow (1) (r), Round (3) (rr), Sand (4) 
 (sss), Taylor (r), Upper Nashotah (r), Wildcat (sss). 
 
 This species is quite unlike other members of the genus since the 
 processes are much more delicate and the cells larger. 
 
 CHRYSIDASTRUM Lauterborn 1913. 
 
 Cells joined to one another by pseudopodial processes and arranged 
 to form free-floating linear colonies of 2-16 cells that are not enclosed 
 by a gelatinous envelope. Cells spherical, with the periplast undiffer- 
 entiated but extending into several long, delicate, pseudopodia-like pro- 
 cesses. Chromatophore single, central, and laminate to band-shaped. 
 
 Reproduction unknown. 
 
 Chrysidastrum catenatum Lauterborn. PI. 14 , Figs. 7 - 8 . 
 
 in Pascher, D. Siisswasserfl. Deutschl., dsterr. u. d. Schw. *2, Flagellatae 2: 91, 
 f.cj. 144. 1913. 
 
 Specific characters the same as those of the genus. (Euplanktont). 
 
 Diam. cells (without processes) 12-15 /a; (with processes) 45-60 fi. 
 
 Kitten (rr), Mud (2) (rr), Wildcat (rrr). 
 
 The cell shape is quite like that of Chrysamoeha but the definite or- 
 ganization into a linear colony and the single laminate chromatophore 
 are points of difference. The alga should also be compared with RMzo- 
 chrysis planctonica Pascher. 
 
WISCONSIN PHYTOPLANKTON 
 
 79 
 
 Class HETEROKONTEAE. 
 
 Cells microscopic or macroscopic; free-floating, sessile, or epiphytic. 
 Cell shape spherical, ovoid, pyriform, cylindrical or irregular. Cells 
 solitary, in colonies of regular to irregular shape, or united to form 
 simple filaments. Colonies or individual cells with or without a gelat- 
 inous envelope. Chromatophores one to many, parietal, generally disci- 
 form, rarely laminate, yellowish- green in color and without a pyrenoid. 
 Assimilation product oil, never starch. Cells uninucleate or multinu- 
 eleate. 
 
 Asexual reproduction by vegetative cell division and a formation of 
 zoospores. Zoospores ovoid to pyriform, with two cilia of unequal 
 length and generally more than one yellowish-green chromatophore. 
 
 Sexual reproduction, insofar as known, isogamous, by zoogametes that 
 are similar in structure to the zoospores. 
 
 The various genera of the Heterokontae were formerly scattered 
 throughout the different families of the Chlorophyceae. The distinguish- 
 ing characteristics of this class are the yellowish-green chromatophores 
 without pyrenoids, with oil not starch the assimilation product; and 
 zoospores with two cilia of unequal length. There are three orders in 
 the class and representatives of all three are found in Wisconsin lakes. 
 
 KEY TO THE ORDERS. 
 
 V'egetative cells motile Heteeochloridales 
 
 Vegetative cells immobile. 
 
 Cells solitary or in colonies, never in filaments Heteeococcales 
 
 Cells united to form simple filaments Heteeotrichales 
 
 Order HETEROCHLORIDALES. 
 
 Cells solitary, free-swimming, ovoid to pyriform in shape. Motile 
 phase dominant, rarely metamorphosing over into an amoeboid or pal- 
 mella phase. Cells with two cilia of unequal length, one or more chro- 
 matophores of a yellowish-green color and without an eyespot. Assimi- 
 lation product leucosin or fat, never starch. 
 
 Asexual reproduction by vegetative division of cells. 
 
 Sexual reproduction unknown. 
 
 The order has but one family, the Chloramoebaceae, whose characters 
 are those of the order. 
 
80 
 
 WISCONSIN PHYTOPLANKTON 
 
 CHLOROCHROMONAS Lewis 1913. 
 
 Cells solitary, generally free-swimming, very rarely amoeboid, some- 
 times attached to substratum by a posterior pseudopodia-like structure. 
 Cell shape pyriform to sub-ovoid, with an oblique depression at the 
 anterior end. Cilia two, at the anterior end of the cell and of unequal 
 length. Chromatophores two, yellowish-green in color, oblong with 
 rounded ends in front view, somewhat flattened in side view. Cells 
 with a single anterior vacuole, one nucleus, and without an eyespot. 
 Nutrition holophytic or saprophytic. 
 
 Reproduction by longitudinal fission when in the motile phase. 
 
 Chlorochromonas minuta Lewis. PI. 15, Figs. 1-3. 
 
 Arch. f. Protistenkunde 32: 254, ph 12, figs. 1-24. 1913. 
 
 Characters as described above. (Euplanktont). 
 
 Cells 4.5-9.5 (av. 6.3) p, long, with an average breadth of 4.7 p. 
 Average length of longer cilium 12.5 p, of the shorter 2.9 p. 
 
 Mendota. 
 
 This organism was first found by Lewis in a dish containing sections 
 of basswood {Tilia americana) that had been standing for some time in 
 a dish of tap water, which is drawn directly from Lake Mendota. I 
 have never noted the alga in plankton collections but have no doubt 
 but that a continued search will demonstrate its presence in Lake Men- 
 dota. During the past winter (1917-18) the alga appeared in an in- 
 fusion of fern leaves which had been standing for some time in tap 
 w^ater. This shows that the original source of the alga was the water 
 with which the sections were moistened and not the Tilia. 
 
 Order HETEROCOCCALES. 
 
 Cells spherical, ovoid, saccate, or elongate cylindrical ; solitary or in 
 colonies of definite or indefinite shape; free-floating or sessile. Cells 
 of colonies embedded in a hyaline, gelatinous envelope or a tough elastic 
 membrane. Chromatophores one to many, yellowish-green to nearly 
 grass-green in color and with oil not starch the assimilation product. 
 
 Asexual reproduction by vegetative cell division and a formation of 
 zoospores with cilia of unequal length. 
 
 Sexual reproduction by a fusion of zoogametes that are similar in 
 stT'ucture to the zoospores is known in certain genera. 
 
WISCONSIN PHYTOPLANKTON 81 
 
 KEY TO THE FAMILIES. 
 
 Cells epiphytic Chlobosaccaceab 
 
 Cells free-floating. 
 
 Length of cells several times the diameter Ophiocytiaceae 
 
 Length of cells less than twice the diameter. 
 
 Cells irregularly distributed throughout an ovoid 
 
 gelatinous envelope Chlorobotrydaceae 
 
 Cells arranged about a common center within an 
 
 irregular gelatinous envelope Botryococcaceae 
 
 Family CHLOROSACCACEAE. 
 
 Cells epiphytic, solitary, gregarious, or embedded in an amorphous 
 gelatinous matrix. Chromatophores one to several, parietal, of a yel- 
 lowish-green color, with oil not starch the assimilation product. 
 
 Asexual reproduction by a formation of zoospores that presumably 
 have two cilia of unequal length. 
 
 Sexual reproduction by the fusion of isogamous zoogametes. 
 
 PERONIELLA Gobi 1887. 
 
 Cells epiphytic upon other algae, solitary or gregarious. Shape of 
 mature cells globular to ovoid, of young cells pyriform to ovoid. Cells 
 attached to substratum by a delicate hyaline stipe that is usually some- 
 what longer than the cell. Chromatophores one to two, pale yellowish- 
 green, without pyrenoids or starch and with oil as the assimilation 
 product. 
 
 Asexual reproduction by the division of cell contents into 2-4-8 uni- 
 ciliate ( ?) zoospores that are liberated by a lateral rupture of mother 
 cell wall. Zoospores swarming a short time and then coming to rest 
 upon substratum and developing into vegetative cells. 
 
 Peroniella planctonica G. M. Smith. PI. 15, Fig. 4. 
 
 Bull. Torr. Bot. Cl. 43: 476, pi. 25, M- 15. 1916. 
 
 Cells broadly ovoid to pyriform, with a long, delicate, hyaline stipe 
 that is without a disc or other enlargement at the base. Chromato- 
 phores usually single, rarely two, pale yellowish-green, without pyre- 
 noids or starch. (Euplanktont). 
 
 Cells (without stipe) 6-9.5 /a long; (with stipe) 15-18 /a. Stipe 8-10 /a 
 long, 1.2 /A broad. 
 
 In gelatinous envelope of SpJiaerozosma filaments. 
 
 Devils (1) (rr). 
 6 
 
82 
 
 WISCONSIN PHYTOPLANKTON 
 
 Family CHLOROBOTRYDACEAE. 
 
 Cells solitary or in free-floating colonies enclosed by a copious, homo- 
 geneous, gelatinous envelope. Colony generally with a small number 
 of cells and with cell number a multiple of two. Cells spherical, ovoid, 
 angular, or cylindrical j with a firm cell wall that is sometimes impreg- 
 nated with a slight trace of silica ; and with one to many parietal, disci- 
 form, yellowish-green chromatophores without pyrenoids. 
 
 Asexual reproduction by vegetative cell division or a formation of 
 zoospores with two cilia of unequal length. 
 
 CHLOROBOTRYS Bohlin 1901. 
 
 Cells rarely solitary, generally in colonies of 2-4r-8-16 or more em- 
 bedded in a copious, homogeneous, hyaline, gelatinous envelope. Cells 
 spherical to broadly ovoid, with a heavy wall that sometimes contains 
 a small amount of silica. A conspicuous red pigment spot present in 
 cells at times. 
 
 Reproduction by vegetative division of cells in three directions. 
 
 KEY TO THE SPECIES. 
 
 Cells ovoid, with few chromatophores C. Limneticus 
 
 Cells spherical, with numerous chromatophores C. Reguiabis 
 
 Chlorobotrys regularis (W. West) Bohlin. PI. 15 , Fig. 10 . 
 
 Bih. kgl. Sv. Vet.-Ak. Handl. 27, Afd. 3, No. 4: 34. 1901; W. & G. S. West, 
 Jour, of Bot. 41 : 78, pi. 447, figs. 7-10. 1903. 
 
 Chlorococcum regulare W. West, Jour. Roy. Micr. Soc. 1892: 737, pi. 10, 
 fig. 55. 1892. 
 
 Cells spherical to subspherical ; rarely solitary, generally in colonies 
 of 2-4-8-16 enclosed by a copious, hyaline, homogeneous, gelatinous 
 envelope. Cell wall thick, sometimes containing a trace of silica. 
 Chromatophores yellowish-green, disciform, parietal, 6-30 in each cell. 
 Cells at times containing a single conspicuous red pigment spot. (Ty- 
 choplanktont). 
 
 Diam. cells 10-27 p. Diam. colonies 35-90 p. 
 
 North Turtle (rrr). 
 
 Chlorobotrys limneticus G. M. Smith. PI. 15, Fig. 9. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 653, pi. 14, fig. 10. 1918. 
 
 Cells ovoid, irregularly distributed within a homogeneous, hyaline, 
 gelatinous envelope. 10-30 cells in a colony. Chromatophores 3-4, 
 
WISCONSIN PHYTOPLANKTON 
 
 83 
 
 pale yellowish-green, disciform, parietal, and without pyrenoids. (Eu- 
 planktont) . 
 
 Cells 5-6 broad, 6-8 fx long. Diam. colonies 40-200 /x. 
 
 Camp (rr). 
 
 Family BOTRYOCOCCACEAE. 
 
 Cells always in free-floating colonies of deflnite or indefinite shape. 
 Number of cells in colony generally indefinite, few or many. Colony 
 enclosed by an envelope that may be hyaline or colored, gelatinous or 
 leathery. Cells usually ovoid, rarely spherical; with 1-2 parietal, 
 laminate to disciform, yellowish-green to nearly grass-green chromato- 
 phores without pyrenoids and with oil as the assimilation product. 
 
 Asexual reproduction by vegetative cell division. Zoospore forma- 
 tion or sexual reproduction unknown. 
 
 BOTRYOCOCCUS Kiitzing 1849. 
 
 Cells in free-floating colonies of indefinite shape. Cells closely ap- 
 posed to one another and enclosed by a gelatinous or tough membrane 
 that is sometimes wrinkled and folded. Colonies generally with cells 
 in several aggregates that are connected by broad or delicate strands 
 of the colonial integument. Cell shape spherical, ovoid, or cuneate. 
 Groups of cells arranged in a single layer around a common center, or 
 irregular in arrangement. Chromatophore single, parietal, laminate 
 to disciform, yellowish-green to nearly grass-green in color and without 
 a pyrenoid. 
 
 Reproduction by vegetative division of cells. 
 
 KEY TO THE SPECIES. 
 
 Cells held together by a thin gelatinous envelope B. Sudeticus 
 
 Cells held together by an irregular tough membrane. 
 
 Membrane completely enclosing cells B. BRAmm 
 
 Membrane covering base only of cells B. Peotuberans var. Minor 
 
 Botryococcus sudeticus Lemmermann. PI. 15, Fig. 8. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon. 4: 111, figs. 6-7. 1896. 
 
 Botryococcus Braunii G. S. West non Kiitzing, Brit. Freshw. Algae 237, figs. 
 106A-106B. 1904; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18 ": 545 
 
 1916. 
 
 Colonies free-floating ; spherical or irregular ; with cells held in botry- 
 oidal clusters by a hyaline gelatinous envelope and frequently joined 
 10 one another by broad or narrow strands of the gelatinous envelope. 
 Cells spherical to subspherical, 16-32 or more in each botryoidal group. 
 
84 
 
 WISCONSIN PHYTOPLANKTON 
 
 and arranged around a common center. Chromatophore single, cup- 
 shaped to disciform, without a pyrenoid. (Euplanktont). 
 
 Diam. cells 6-13 fx. 
 
 Clear (rr), Waubesa (rrr). 
 
 This is the B. Braunii Ktz. of the preliminary list, the identification 
 being based upon G. S. West’s description of B. Braunii in his British 
 Freshwater Algae. Dr. West has since informed me that the Ineffigiata 
 neglecta of that work is B, Braunii Ktz. and the B. Braunii described 
 therein is B. sudeticus Lemm. 
 
 Botryococcus Braunii Kiitzing. PL 15, Fig. 5. 
 
 Species algarum 892. 1849; Presenius, Abh. Senckenb. Naturf. Ges. 2: 239, 
 pi. 11, figs. 27-33. 1858. 
 
 Ineffigiata neglecta W. & G. S. West, Jour. Roy. Micr. Soc. 1897 : 503. 1897; 
 Jour, of Bot. 41 : 80, pi. 447, figs. 1-6. 1903. 
 
 Cells joined in small free-floating colonies of irregular shape that are 
 without a conspicuous gelatinous envelope but completely enclosed by 
 a tough, elastic, hyaline to orange colored membrane that is pro- 
 duced into irregular wrinkles, folds, and spines. Colonies frequently 
 united to form compound colonies by long delicate projections of the 
 colonial envelope. Cells ovoid or ellipsoid in shape and forming a 
 single layer around a central cavity. Chromatophore single, cup-shaped 
 to laminate, yellowish-green to nearly grass-green in color, without a 
 pyrenoid. Assimilation product a reddish oil that may color the whole 
 colony a brick red. (Facultative planktont). 
 
 Cells 3.5-5.5 fx broad, 5.7-10.5 fx long. Simple colonies up to 100 g. 
 in diam. ; compound colonies up to 1.5 mm. 
 
 Balsam (rr). Bear (3) (rr). Bear Trap (rrr), Beaver (2) (rr), Beaverdam 
 (ss), Birch Island (rrr), Birch (2) (rr), Boulder (rrr). Browns (sss). Camp 
 (rrr), Carson (r). Center (r). Chain (rrr), Chetac (rr). Clam (rrr), Clare 
 (r), Cochrane (rrr). Crawling Stone (rr). Crooked (sss). Deer (rr), Delavan 
 (rrr), Des Moines (rr). Devils (1) (r). Devils (2) (r). Devils (3) (rrr), 
 East (rr), Elizabeth (rr). Green (1) (rr). Green (2) (rrr). Grindstone (r). 
 High (rr). Horse (rrr). Horseshoe (1) (rr), Island (rr), Jennie (rr), Jones 
 (rrr), Kawaguesaga (rrr), Kegonsa (r), Kimball (rrr). Kitten (rrr). Lac 
 Court Oreilles (sss). Lac du Flambeau (rrr), Little Bass (1) (rrr). Little 
 Butternut (rrr). Little Crooked (rrr). Little Doctor (rr). Little Rice (1) (rr). 
 Long (1) (rrr). Lower Nashotah (r). Lynx (rr), Mary (sss), Mendota (ss), 
 Mercer (rrr). Mill (rrr), Monona (sss). Mud (3) (rrr). Mud Hen (sss), Nancy 
 (r), Nicaboyne (rrr). No Mans (rr). Paddock (r). Palmer (rrr), Pardee (sss). 
 Pike (rrr), Pokegama (1) (rrr), Pokegama (2) (rrr). Poor Farm (rrr). Re- 
 serve (rr). Rice (1) (rr). Round (2) (rrr), St. Croix (rrr). Sand (1) (r). 
 Sand (2) (rr). Sand (3) (rr), Sand (4) (rrr), Shell (rr). Silver (2) (r), 
 Sishebogema (rr). South Turtle (rr). Spirit (rrr). Tied Canoe (rrr), Travis 
 (rrr). Upper Nashotah (sss), Wapagossett (rr), Waubesa (r). White Ash 
 (rrr), Whitefish (rrr), Wildcat (rrr), Winnebago (rrr). Wolf (rrr). 
 
WISCONSIN PHYTOPLANKTON 
 
 85 
 
 Botryococcus protruberans var. minor G. M. Smith. PI. 15, Figs. 6-7. 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19': 652, pi. 14, figs. 6-7. 1918. 
 
 Cells in colonies of 4-8-16 or more held together by a tough gelat- 
 inous membrane. Colonies frequently joined to one another by long 
 hyaline strands of the colonial envelope. Cells ovoid to cuneate-ovoid, 
 with their bases embedded in the colonial envelope and their apices 
 not enclosed by the envelope. Cells arranged in a single layer around 
 a central cavity. Chromatophores single, yellowish-green, laminate, 
 occupying the median portion of the cell. (Euplanktont). 
 
 Cells 8-9.5 /A long, 5-6.5 fi broad at the widest part. 
 
 Diamond (rrr), George (aa), Hillman (rr), Lindy (rr). Oak (ss), Pardee 
 (rr), Sanford (rr), South Crab (s). 
 
 This species is distinguished from the foregoing by the smaller num- 
 ber of cells in the colony and the projection of the apex of the cells 
 through the colonial integument. 
 
 Family OPHIOCYTIACEAE. 
 
 Cells sessile or free-floating, solitary or colonial. Length of cells 
 generally several times the breadth. Cells straight, curved, sigmoid, or 
 spiral; with or without terminal spines. Chromatophores yellowish- 
 green ; annular, parietal and few in number ; or disciform, parietal and 
 numerous ; without pyrenoids and with oil as the assimilation product. 
 
 Asexual reproduction by division of cell contents to form 4-16 aplano- 
 spores or 2-8 biciliate zoospores with cilia of unequal length. 
 
 Sexual reproduction unknown. 
 
 OPHIOCYTIUM Nageli 1849. 
 
 Cells free-floating or epiphytic, solitary or colonial ; straight, arcuate, 
 sigmoid, or spiral elongate cylinders with rounded or capitate ends 
 that may be apiculate or attenuated into a single spine. Chromato- 
 phores pale yellowish-green, H-shaped in optical cross section, without 
 pyrenoids and with oil as the assimilation product. Cells coenocytic. 
 Cell wall consisting of a homogeneous cap at one end and with the re- 
 maining portion of the wall composed of a number of laminate layers. 
 
 Asexual reproduction by division of cell contents to form 4-16 aplano- 
 spores or 2-8 biciliate zoospores with cilia of unequal length. 
 
86 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Poles of cells without spines O. Pabvulum 
 
 Poles of cells with spines O. Capitatum 
 
 Ophiocytium parvulum (Perty) A. Braun. PI. 15, Fig. 11. 
 
 Alg. unicell. 55. 1855; Lemmermann, Hedwigia 38; 33, pT. 4, figs. 30-'33. 1899. 
 
 Cells cylindrical, several times as long as broad; straight, arcuate, or 
 spiral; poles rounded and without spines. Chromatophores several, 
 H-shaped in cross section, pale yellowish-green. Oil droplets rarely 
 present. ( Tychoplanktont) . 
 
 Cells 3-9 fi broad. 
 
 Fishtrap (rrr). 
 
 Ophiocytium capitatum Wolle. PI. 15, Figs. 12-13. 
 
 Freshw. Algae of U. S. 176, pi. 158, figs. 3-7. 1887. 
 
 Cells solitary ; arcuate, sigmoid, or spiral cylinders with poles rounded 
 and the same size as or slightly larger than the median portion of the 
 cell. Length of cell 5-10 times the breadth. Poles of cells with a 
 single short, straight, or slightly curved spine. (Tychoplanktont). 
 
 Cells 5-10 /X broad, up to 85 fx long. Spines 5-7 /x long. 
 
 Tied Canoe (rrr). 
 
 var. LONGiSPiNUM (Mobius) Lemmermann. PI. 15, Figs. 14^16. 
 Hedwigia 38 : 32, pi. 4, figs. 21-25. 1899. 
 
 Cells cylindrical ; straight, arcuate, or spirally twisted, with a single 
 long spine at each pole that is nearly as long as the cell. (Euplank- 
 tont). 
 
 Diam. cells 4.5-6 fx. Length of spines 16-50 fx. 
 
 George (rr), Loon (rr). 
 
 Order HETEEOTRICHALES. 
 
 Cells in simple, unbranched filaments; with or without a gelatinous 
 envelope. Cell wall firm, fairly thick, lamellated in structure and 
 breaking down into H-shaped pieces at the time of reproduction. Chro- 
 inatophores few to several, yellowish-green, disciform, and parietal. 
 Cells usually uninucleate. Assimilation product oil, not starch. 
 
 Asexual reproduction by the formation of aplanospores or by zoo- 
 spores with two cilia of unequal length. 
 
WISCONSIN PHYTOPLANKTON 
 
 87 
 
 Sexual reproduction by the fusion of isogamous zoogametes. 
 
 There is but one family in the order, the Tribonemaceae, whose char- 
 acters are the same as those of the order. 
 
 TRIBONEMA Derbes and Solier 1856. 
 
 Cells in simple unbranched filaments destitute of an enveloping gelat- 
 inous sheath. Cells cylindrical or barrel-shaped, with flattened end 
 walls. Cell wall frequently of considerable thickness and laminate in 
 structure. Chromatophores two to several, yellowish-green, disciform, 
 parietal, without starch and with oil as the assimilation product. 
 
 Asexual reproduction by aplanospores and biciliate zoospores that 
 have cilia of unequal length. The cell wall pulling apart and breaking 
 down into H-shaped pieces at the time of reproduction. 
 
 Sexual reproduction by the fusion of isogamous zoogametes. 
 
 Tribonema minus (Wille) Hazen. PI. 15, Figs. 17-18. 
 
 Mem. Torr. Bot. Cl. 11: 185, pi. 25, figs. 7-8. 1902. 
 
 Filaments generally forming a floccose yellowish to greenish mass. 
 Cells cylindrical or slightly swollen in the median portion, generally 
 2-4, rarely 6, times as long as broad. Chromatophores 2-4, yellowish- 
 green, disciform, parietal, generally in pairs. (Facultative planktont). 
 
 Cells 5-6 /A broad, 10-35 fi long. 
 
 Green (1) (rrr), Mendota (s). 
 
 Members of this genus are frequently found in ditches but seldom in 
 lakes. During the past season T. minus has appeared in considerable 
 quantity in the plankton of Lake Mendota, although previous to this 
 time the alga has not been found in the plankton. A similar sudden 
 appearance of T. homhycina forma depauperata Wille, a form closely 
 related to T. minus, has been noted in the plankton of Danish lakes by 
 Wesenberg-Lund (Studier over de danske soers Plankton p. 100. 
 Kjobenhavn, 1904). 
 
88 
 
 WISCONSIN PHYTOPLANKTON 
 
 Class CHLOROPHYCEAE. 
 
 Cells with the coloring matter restricted to definite bodies that are 
 grass-green in color (chloroplasts). Cells free-floating, sessile, epi- 
 phytic, epizootic, or endophytic ; solitary, in microscopic to macroscopic 
 colonies of definite or indefinite shape that are naked or enclosed by a 
 hyaline to colored, homogeneous or lamellated, firm or gelatinous en- 
 velope. Colonies with all of the cells morphologically alike or differen- 
 tiated. Colonies growing in all directions; forming simple, laminated, 
 or parenchymatous plates; or developing into simple or branched fila- 
 ments. Cells motile throughout the whole life history, for a portion 
 of it, or immobile at all times. Cells variously shaped ; spherical, hemi- 
 spherical, ovoid, ellipsoid, spindle-shaped, acicular, reniform, angular, 
 irregular, cylindrical, conical, simple to branching tubular, or con- 
 stricted to form two symmetrical halves of various shapes. Cells con- 
 taining one or more disciform, laminate, cup-shaped, astral, ribbon-like, 
 or reticulate chloroplasts that are parietal, axial, or central in position 
 and have one or more centers for the synthesizing of starch (pyrenoids) . 
 Assimilation product oil in a few cases. Cells uninucleate or multinu- 
 cleate (coenocytic) ; containing a central vacuole, numerous small vacu- 
 oles, or without vacuoles. Contractile vacuoles chiefly confined to the 
 motile genera. 
 
 Asexual reproduction by vegetative cell division, aplanospores, zoo- 
 spores, or akinetes. 
 
 Sexual reproduction by isogamous or heterogamous zoogametes, isoga- 
 mous aplanogametes, or heterogamous motile antherozoids and immobile 
 oospheres. Zygotes germinating immediately, or after a period of rest ; 
 with a direct or an indirect germination into the plant bod}". 
 
 KEY TO THE DIVISIONS 
 
 Sexual or asexual reproductive bodies with 2-4 cilia of equal length. . I sokontak 
 Sexual or asexual reproduction by non-ciliate reproductive bodies Akontae 
 
 Division ISOKONTAE. 
 
 Cells solitary or in colonies and showing the same great range of 
 variation in shape, organization of the colony, interior structure, and 
 method of reproduction noted in the description of the class. 
 
 Included in this division is the important plankton family of the 
 Autosporaceae where no motile phase of reproduction is known. The 
 
WISCONSIN PHYTOPLANKTON 
 
 89 
 
 close phylogenetic connection between the Autosporaceae and the other 
 members of the Protococcales is, however, perfectly evident. 
 
 KEY TO THE ORDERS. 
 
 Cilia normally present throughout the whole life cycle Volvocalks 
 
 Cilia present at time of reproduction only. 
 
 Cells in simple or branched filaments. 
 
 Cells uninucleate, with a single laminate chloroplast. . . .Ulotrichalxs 
 Cells multinucleate, with one or more chloroplasts. .Siphonooladiales 
 Cells solitary or in simple colonies, generally of microscopic 
 
 size Protococcales 
 
 Order VOLVOCALES. 
 
 Cells normally ciliate and motile during the vegetative phases of the 
 life cycle. Solitary or organized into colonies of definite form that 
 generally contain a definite number of cells. Protoplasts rarely naked, 
 usually with a differentiated outer cellulose covering that may be par- 
 tially gelatinized. Shape of protoplast spherical, ovoid, disciform, 
 pyramidate, or irregularly radiate. Cells with a single cup-shaped to 
 irregular chloroplast, with or without pyrenoids ; with 2-4 cilia at the 
 anterior end; generally with a disciform to bacilliform eyespot, two to 
 several contractile vacuoles, and one nucleus. Palmella stages fre- 
 quently arising in the unicellular members. 
 
 Asexual reproduction by division of cell contents into 2-16 zoospores ; 
 or a development of special, or all cells of the colony into autocolonies. 
 
 Sexual reproduction by isogamous zoogametes; heterogamous zoo- 
 gametes; or small motile antherozoids and large immobile oospheres. 
 
 Many hold with G. S. West (Algae 151, 1916) ^‘that it is very doubt- 
 ful if the Volvocineae have sufficient claims to be removed from the 
 Protococcales and elevated to a group of equal rank (the ‘ Volvocales’) 
 There is a very close relationship between the ‘‘palmella^’ stage of 
 various unicellular Volvocales and the family Palmellaceae of the Pro- 
 tococcales. This represents to me, however, a close phylogenetic rela- 
 tionship between the two and not a justification for uniting in the same 
 order forms with mobile vegetative cells and those which are immobile. 
 
 KEY TO THE FAMILIES. 
 
 2 cilia at the anterior end of cells. 
 
 Cells solitary CnLAMYDOMOif adaceae 
 
 Cells in definite coenobia Volvocaceae 
 
 4 cilia at the anterior end of cells Carteriaceae 
 
90 
 
 WISCONSIN PHYTOPLANKTON 
 
 Family CHLAMYDOMONADACEAE. 
 
 Cells normally solitary and motile during the vegetative phases of 
 the life history. Spherical, ovoid, cylindrical, sub-acicular, compressed, 
 or quadrately projected. Chloroplast cup-shaped to laminate, lateral 
 or posterior in position, with or without pyrenoids. Cells uninucleate, 
 with or without an eyespot, with two cilia of equal length that generally 
 have two contractile vacuoles at their base. Cells at times becoming 
 immobile and developing into amorphous colonies enclosed by a wide 
 gelatinous envelope. 
 
 Asexual reproduction by the division of cell contents to form 2-16 
 biciliate zoogametes. 
 
 Sexual reproduction by the fusion of isogamous zoogametes. 
 
 CHLAMYDOMONAS Ehrenberg 1832. 
 
 Cells normally solitary and motile ; though capable of coming to rest, 
 losing the cilia, developing a gelatinous envelope and dividing vegeta- 
 tively to form colonies containing an indefinite number of cells. Cells 
 spherical, fusiform, ovoid, pyriform, or ellipsoid ; with two cilia of equal 
 length at the anterior end. Chloroplast typically cup-shaped, posterior, 
 and with one pyrenoid. Cells uninucleate, generally with two con- 
 tractile vacuoles at the base of the cilia; with or without an eyespot 
 which, when present, lies in the anterior portion of the cell. 
 
 Asexual reproduction by division of cell contents to form 2-16 bicili- 
 ate zoospores. 
 
 Sexual reproduction isogamous, by the division of cell contents into 
 8-64 zoogametes that fuse in pairs to form smooth-walled or sculptured 
 zygotes. 
 
 KEY TO THE SPECIES. 
 
 Cells spherical. 
 
 Anterior end without a beak C. Globosa 
 
 Anterior end with a pronounced beak C. Epiphytica 
 
 Cells ovoid. 
 
 Chloroplast cup-shaped and basal C. Snowti 
 
 Chloroplast laminate, lateral, or basal C. Dhtobryonj 
 
 Chlamydomonas globosa Snow. PI. 16, Fig. 8. 
 
 Bull. U. S. Fish Comm. 22: 389, pi. 1, figs. IIP-III®. 1903. 
 
 Cells spherical or slightly ellipsoid, without an anterior beak. Chloro- 
 plast cup-shaped, occupying the greater portion of the cell, with one 
 pyrenoid at the posterior end. Eyespot present, small, generally in the 
 middle third of the cell. Cilia slightly longer than the cell and with a 
 
WISCONSIN PHYTOPLANKTON 
 
 91 
 
 single contractile vacuole at their base. Palmella stages frequent and 
 usually containing 4-8 cells. (Euplanktont). 
 
 Cells 5-10 fji broad. 
 
 Crawling Stone (rr). 
 
 Chlamydomonas epiphytica sp. nov. PI. 16, Figs. 11-13. 
 
 Cells spherical to pyriform, with a very pronounced anterior beak. 
 Chloroplast cup-shaped, forming a thin layer next to the cell wall, with 
 a single pyrenoid at the posterior end. Eyespot conspicuous, disciform, 
 at the anterior end of the cell. Cilia more than twice as long as the 
 cell. Cells frequently coming to rest in the gelatinous envelope of 
 Microcystis colonies but not losing the eyespot and usually retaining 
 the cilia. (Euplanktont). 
 
 Cells 7-8 broad, 8-9 fi long ; cilia 20-25 fi long. 
 
 Elizabeth (s), Mary (sss). 
 
 The alga is frequently found in the gelatinous envelope of Microcystis 
 colonies and suggests an epiphytic CJiaracmm but the presence of cilia 
 shows that it is a ChlaniydomoTias. 
 
 Chlamydomonas Snowh Printz. PI. 16, Figs. 9-10. 
 
 Skr. Vidensk.-Selsk. i Kristiana, Mat.-Naturv. Kl. 1913': No. 6: 18. 1914. 
 
 Chlamydomonas communis Snow, Bull. U. S. Fish Comm. 22: 388, pi. 1, 
 figs. ir-IP. 1903. 
 
 Cells motile but frequently forming palmella stages containing a 
 considerable number of cells. Cell shape ovoid to ellipsoid, with a very 
 inconspicuous anterior beak. Chloroplast cup-shaped, massive in the 
 posterior portion, with one pyrenoid at the center of the cell. Cilia 
 slightly longer than the cell; eyespot inconspicuous, variable in posi- 
 tion. (Facultative planktont). 
 
 Cells 6.5-8 fi broad, 10-15 y. long. 
 
 Nancy (rr). 
 
 Chlamydomonas dinobryoni sp. nov. PI. 16, Pigs. 5-7. 
 
 Cells rarely free-swimming, generally in large numbers and filling 
 the empty receptacles of Dinohryon colonies. Cells small, ovoid to pyri- 
 form in shape, without an anterior beak; with two short cilia at the 
 anterior end. Chloroplast disciform to hemispherical, basal or lateral 
 in position, containing a p 3 rrenoid. Eyespot and contractile vacuoles 
 not observed. (Euplanktont). 
 
 Cells 2-3 y broad, 3.5-5 y long; cilia 6-8 y long. 
 
 Lac du Flambeau (ss), Long (3) (s), Pokegama (2) (r). 
 
92 
 
 WISCONSIN PHYTOPLANKTON 
 
 Many of the empty Dinohryon receptacles in these three connecting 
 lakes were filled with a minute green organism. These had cilia, even 
 when in the receptacle, and on the slightest crushing of the receptacle 
 began swimming around outside of it. Since cilia are constantly pres- 
 ent the alga is a CMamydomonas and not one of the Palmellaceae col- 
 lected at the time of reproduction. 
 
 Family CARTERIACEAE. 
 
 Cells normally motile and with four cilia of equal length at the an- 
 terior end. Solitary, or in coenobia containing a definite number of 
 cells. Cell shape spherical, ovoid, ellipsoid, cardioid, pyriform, or 
 lenticular. Cells enclosed by a definite wall, and with or without a 
 cup-shaped to lenticular chloroplast that is with or without pyrenoids. 
 Eyespot generally present, conspicuous, and at the anterior end of the 
 cell. Cells frequently with contractile vacuoles at the base of the 
 cilia. Palmella stages known in the solitary members of the family. 
 
 Asexual reproduction by the division of cell contents into 2-16 tetra- 
 ciliate zoospores or into autocolonies. 
 
 Sexual reproduction isogamous, by a fusion of tetraciliate zoogametes. 
 
 CARTERIA Diesing 1866. 
 
 Cells solitary, generally motile throughout the vegetative phases of 
 the life cycle. Spherical, ovoid, ellipsoid, or cardioid in shape; with 
 four cilia of equal length at the anterior end. Cell contents consisting 
 of a single cup-shaped chloroplast that contains a pyrenoid; one eye- 
 spot; and two contractile vacuoles at the base of the cilia. Palmella 
 stages containing an indefinite number of cells are found at times. 
 
 Asexual reproduction by division of cell contents to form 2-8 tetra- 
 eiliate zoospores. 
 
 Sexual reproduction by the division of cell contents to form 4-64 
 tetraciliate zoogametes that fuse in pairs to form zygotes with smooth 
 or sculptured walls. 
 
 KEY TO THE SPECIES. 
 
 Cells ellipsoid C. Klebsh 
 
 Cells cardioid C. Cobdiformis 
 
 Carteria cordiformis (Carter) Diesing. PI. 16 , Fig. 1 . 
 
 Sitzbr. d. k. Ak. d. Wiss. Wien, Mat.-Naturw. Kl. 52?: 356. 1866; Dill, Jahrb. f. 
 wlss. Bot. 28 : 353, pi. 5, figs. 42-44. 1895. 
 
 Cells cardioid in shape with four cilia at the base of the apical de- 
 pression. Chloroplast cup-shaped, fairly massive, with a single pyre- 
 
WIBC0N8IN PHYTOPLANKTON 
 
 93 
 
 noid in the posterior region. Cells with two contractile vacuoles at 
 the base of the cilia and with a disciform eyespot in the upper third 
 of the cell. (Tychoplanktont). 
 
 Cells 9-16 broad, 12-20 /t long. 
 
 Crawling Stone (rrr). 
 
 Carteria Klebsii (Dangeard) Dill. PI. 16, Figs. 2-4. 
 
 Jahrb. f. wiss. Bot. 28 : 353. 1895; Printz, Skr. Vidensk.-Selsk. Kristiana, Mat.- 
 Naturv. Kl. 1913': No. 6: 13. 1914. 
 
 Pithiscus Klebsii Dangeard, Ann. Sci. Nat. 7 Ser. Bot. 7: 137, pi. 12, figs. 
 1-6. 1888. 
 
 Cells solitary, ellipsoid to ellipsoid-cylindrical, Avith a more or less 
 prominent beak at the anterior end. Chloroplast cup-shaped, massive, 
 with a large pyrenoid at the posterior end. Cells without an eye-spot 
 and with two contractile vacuoles at the base of the cilia. Cilia about 
 twice as long as the cells. Palmella stages containing many cells at 
 times. ( Tychoplanktont ) . 
 
 Cells 5-10 fi broad, 8-16 fi long. 
 
 Pokegama (1) (r). 
 
 Family VOLVOCACEAE. 
 
 Cells always motile and in coenobia of definite shape that contain a 
 definite or an indefinite number of cells. Colonies enclosed in a homo- 
 geneous, hyaline, gelatinous envelope. Cells of colony all alike or dif- 
 ferentiated into vegetative and reproductive cells. Vegetative cells 
 spherical, ellipsoid, pyriform or disciform ; with or without connecting 
 cytoplasmic processes; always biciliate. Chloroplasts generally cup- 
 shaped and containing one pyrenoid. Vegetative cells usually with an 
 eyespot and two contractile vacuoles. 
 
 Asexual reproduction by the division of all or certain of the cells in 
 the colony to form autocolonies. 
 
 Sexual reproduction by a division of all cells in the colony to form 
 isogamous zoogametes or heterogamous zoogametes of slightly different 
 size; or the formation of motile antherozoids from certain cells and 
 large immobile oospheres from others. Zygotes with smooth or sculp- 
 tured walls. 
 
94 : 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE GENERA. 
 
 Colony with cells in a flat plate Gonitjm 
 
 Colony with cells forming a hollow sphere. 
 
 Cells mutually compressed Pandobina 
 
 Cells some distance from one another. 
 
 Asexual reproduction by division of all cells in colony Eudobina 
 
 Asexual reproduction by division of special cells. 
 
 At least half of cells capable of forming autocolonies. . .PLEonoEmA 
 Only a few cells capable of forming autocolonies Volvox 
 
 GONIUM Mueller 1773. 
 
 Colonies of 4^8-16 cells arranged in a flat quadrangular plate and 
 embedded in a common gelatinous matrix or connected by broad gelat- 
 inous strands. Cells ovoid to pyriform, with a single cup-shaped chlor- 
 oplast containing one pyrenoid. Each cell with two cilia of equal 
 length, contractile vacuoles at the base of the cilia, and an eyespot. 
 Four- and eight-celled colonies with the cilia on the same side ; sixteen- 
 celled colonies with the four central cells having their cilia on the same 
 side and the twelve marginal cells with radially arranged cilia. 
 
 Asexual reproduction by simultaneous division of all cells in the 
 colony to form autocolonies, or by a formation of 2-4 zoospores in each 
 cell. 
 
 Sexual reproduction isogamous, by a fusion of biciliate zoogametes. 
 
 Gonium pectorals Mueller. PI. 16 , Figs. 14 - 15 . 
 
 Vermium terrestrium et fluviatilium etc. 1: 60. 1773; Migula, Bot. Cent. 44: 
 
 72, pi. 2, figs. 1-8. 1890; Harper, Trans. -Am. Micr. Soc. 31: 65, pi. 5, figs. 1-19, 
 23. 1912. 
 
 Colonies containing 4-8-16 cells. Usually with 16 cells arranged in 
 two concentric series in a flat plate with truncate corners. Cells con- 
 nected with one another by broad, hyaline, gelatinous processes and 
 with open spaces between the processes; or with processes indistinct 
 and the whole colony embedded in a homogeneous, gelatinous matrix. 
 Outer ring with twelve cells whose long axes lie parallel to the plane 
 of the coenobe. Inner ring of four cells with a large open space at the 
 center and their long axes perpendicular to plane of the coenobe. Cells 
 ovoid to pyriform, with two cilia at the anterior end ; a posterior massive 
 cup-shaped chloroplast ; an anterior eyespot ; and two contractile vacu- 
 oles at the base of the cilia. (Tychoplanktont) . 
 
 Cells 7-11 fjL broad, 10-25 fi long. 
 
 Beaverdam (rrr), Clam (rrr), Duck (rr), Fowler (rrr), Island (r), K»- 
 consa (rrr), Long (1) (rrr), Mendota (rrr), Number One (rr). Pike (rrr), 
 Poplar (rrr). 
 
WISCONSIN PHYTOPLANKTON 
 
 9S 
 
 PANDORINA Bory 1824. 
 
 Colonies always motile, spherical to snbspherical, containing 4-8-16- 
 32 cells mutually compressed to form a hollow sphere with a small 
 open space at the center. Colony enclosed by a fairly copious, firm, 
 hyaline, homogeneous, gelatinous envelope. Cells pyriform to angular 
 by mutual compression, with pointed ends toward the center of the 
 colony; biciliate at the fiattened distal end, the two cilia lying close 
 together while passing through the colonial envelope and then becom- 
 ing markedly divergent. Chloroplast single, massive, cup-shaped, with 
 one pyrenoid at the base. Eyespot single, generally on distal face of 
 the cell. Cells with a definite wall and two contractile vacuoles at the 
 base of the cilia. 
 
 Asexual reproduction by simultaneous division of all cells of the 
 colony to form autocolonies that are liberated by a gelatinization of the 
 colonial envelope. 
 
 Sexual reproduction by a division of each cell of the colony into 
 16-32 zoogametes. Zoogametes showing indications of heterogamy in 
 the slight difference in size and motility of the pairs that fuse to form 
 the smooth walled zygote. 
 
 Pandorina morum Bory. PI. 16, Figs. 16-17. 
 
 Encyc. meth. hist. nat. de Zoophytes 2: 600. 1824; G. S. West, Brit. Freshw. 
 Algae 193, figs. 76a-76h. 1904. 
 
 Colonies generally 16-celled and as described above. (Facultative 
 Planktont) . 
 
 Cells 8-16 fx broad ; colonies 20-^5 ju, broad. 
 
 Bear Trap (rrr), Blake (rrr), Camp (rr), Center (cc), Chetac (rr), Chetek 
 (ss). Deer (rrr)/. Duck (ss). East (rrr), Fowler (rr). Grindstone (s), Hillman 
 (rr). Hooker (s), Kegonsa (sss). Lac Court Oreilles (ss), Lindy (rr). Little 
 Bass (2) (rr). Little Butternut (rr). Little Rice (1) (r). Little Wood (rrr). 
 Long (1) (rrr), Loveless (rr), Lower Nashotah (rr). Lower Nemahbin (rr). 
 Lower Turtle (sss), Mendota (ss), Monona (s). Mud (1) (rrr), Nagawicka 
 (as), Nicaboyne (r), No Mans (rr), Number One (rr), Oconomowoc (rrr), 
 Okauchee (rrr), Pokegama (3) (r). Prairie (r). Rice (1) (r), St. Croix (rr), 
 Sishebogema (rr). South Turtle (sss), Upper Nashotah (rr),, Upper Nemahbin 
 (rr). Upper Turtle (rr), Waubesa (ss), Whitefish (rr), Winnebago (rr). 
 
 EUDORINA Ehrenberg 1832. 
 
 Colonies always motile, spherical or slightly elongate, of 16-32-64 
 cells lying some distance from one another and arranged to form a 
 hollow sphere near the periphery of the homogeneous, hyaline, gelat- 
 inous envelope. Cells spherical, with or without a beak at the point 
 of origin of the two cilia. Cilia parallel while passing through the 
 
96 
 
 WISCONSIN PHYTOPLANKTON 
 
 colonial envelope and then widely divergent. Chloroplast single, cup- 
 shaped, filling practically the whole cell and generally with several pyre- 
 noids. Cells with a firm wall, one or two anterior contractile vacuoles, 
 and a single conspicuous eyespot near the base of the cilia. 
 
 Asexual reproduction by a simultaneous division of all cells to form 
 autocolonies which are liberated by a rupture of the colonial envelope. 
 
 Sexual reproduction heterogamous, dioecious, with all cells of a col- 
 ony developing into large immobile oospheres or plate-like masses of 
 32-64 fusiform antherozoids ; or monoecious with four cells forming 
 antherozoids and the remainder oospheres. Zygote smooth-walled. 
 
 Eudorina elegans Ehrenberg. PI. 19, Pig. 1. 
 
 Abh. d. kgl. Ak. d. Wiss. zu Berlin 1831: 78, pi. 2, 10j^-10d. 1832; G. S. 
 
 West Brit. Freshw. Algae 194, figs. 77a-77f. 1904. 
 
 Colonies generally 32-celled and as described above. (Facultative 
 planktont) . 
 
 Cells 12-24 jx in diam. ; colonies 50-200 fi in diam. 
 
 Balsam (rrr), Bear (3) (ss), Bear Trap (r), Beaverdam (sss). Big Butter- 
 nut (rr), Birch (2) (ss), Birch Islanjd (rr), Boulder (cc), Bryer (rr). Camp 
 (cc), Catherine (ss). Center (sss), Chetac (ss), Chetek (s), Clam (rr), Crawl- 
 ing Stone (rrr), Delavan (sss). Devils (1) (aa). Diamond (sss), Duck (ss), 
 Dunham (ss), Dutchmans (rrr), Elizabeth (rr). Pish (sss), Fowler (rr). 
 Granite (ss). Green (2) (rr), Grindstone (rrr), Hillman (rr). Hill (rrr). 
 Hooker (rr). Horseshoe (1) (rr). Horseshoe (2) (rrr), Howey (rrr). Island 
 (ss), Jennie (r), Kawaguesaga (rr), Kegonsa (ss). Lac Court Oreilles (rr). 
 Lac la Belle (rr). Lake of the Woods (S), Lindy (rr). Little Butternut (rr). 
 Little Wood (rrr). Long (3) (rrr). Loon (rr). Lower Nemahbin (rrr). Lower 
 Turtle (r). Lynx (rr), Meronk (rrr). Middle McKenzie (rr), Nancy (rr), 
 Nicaboyne (ss), No Mans (rr). North Turtle (ss). North Twin (rr). Number 
 One (rr), Okauchee (rr). Paddock (cc). Pine (2) (rrr). Pike (r), Pokegama 
 (2) (rr), Pokegama (3) (ss). Poplar (rr). Prairie (ss). Reserve (rr). Rain- 
 bow (rrr). Rice (1) (ss), Rooney (rr). Round (1) (r). Round (2) (rr). 
 Round (3) (sss). Sand (1) (sss). Sand (4) (rr). Silver (2) (c), Sishebogema 
 (ss). South Crab (rr). South Turtle (sss). Spirit (sss). Squirrel (ss), Tender- 
 foot (rrr), Travis (rrr). Vermilion (rr), Waubesa (sss). White Sand (rrr). 
 
 PLEODORINA Shaw 1894. 
 
 Colonies always motile; spherical to sub-spherical, with 32-128 cells 
 lying some distance from one another just within the periphery of the 
 homogeneous, hyaline, gelatinous, colonial envelope and not connected 
 by cytoplasmic strands. Cells differentiated into those that are purely 
 vegetative in character and those capable of dividing to form daughter 
 colonies. All but four cells of the colony reproductive or about half 
 reproductive and half vegetative. Cells spherical to ovoid in shape. 
 Vegetative cells with a cup-shaped chloroplast containing one pyrenoid; 
 
WISCONSIN PHYTOPLANKTON 
 
 97 
 
 a large anterior eyespot ; two cilia of equal length, with two contractile 
 vacuoles at their base. Reproductive cells at first like the vegetative 
 cells, later with a more massive chloroplast that eventually contains 
 several pyrenoids. The eyespot and cilia of reproductive cells disap- 
 pearing when they are mature. 
 
 Asexual reproduction by a simultaneous division of all reproductive 
 cells to form autocolonies. 
 
 Sexual reproduction (which has been observed in one species only) 
 heterogamous, dioecious, by a division of all reproductive cells to form 
 plates of 64-128 biciliate, fusiform antherozoids ; or a development of 
 reproductive cells into oospheres. Zygotes smooth-walled. 
 
 The validity of this genus has been questioned by many and the view 
 put forward that the alga is but a stage in the life history of Eudorina. 
 Grove (New Phytol. 14; 169-182. 1915) gives a full discussion of the 
 literature of Pleodorina. Although Eudorina elegans is found in a 
 large number of Wisconsin lakes, Pleodorina has been found in but 
 three of them. If Pleodorina is a developmental stage of Eudorina, it 
 is strange that the ‘‘Pleodorina^’ stage has not been observed with 
 greater frequency. The young colonies look very much like those of 
 Eudorina and it is probably on this account that the two have been 
 confused. 
 
 Pleodorina californica Shaw. PI. 17, Figs. 1-3. 
 
 Bot. Gaz. 19 : 279, pi. 27, figs. 1-9. 1894. 
 
 Colonies containing 64-128 cells. Cells usually spherical and about 
 half vegetative and half reproductive. Reproductive cells becoming 
 4-5 times broader than the vegetative cells. (Facultative planktont). 
 
 Vegetative cells 6-14 fi in diam. ; reproductive cells 6-34 p. in diam. 
 Colonies 40-400 p in diam. 
 
 Clam (ss). Mud (1) (cc). Sand (1) (r). 
 
 VOLVOX L. 1758. 
 
 Colonies always motile, spherical to ovoid, containing a large number 
 of cells arranged in a single layer just within the periphery of the 
 homogeneous, hyaline, gelatinous, colonial envelope. Cells differen- 
 tiated into those for vegetative purposes, asexual, and sexual repro- 
 duction. Vegetative cells close together or some distance from one 
 another, with or without cytoplasmic connections of varying thickness. 
 Cell shape spherical, ovoid, or disciform. Individual cells or groups 
 of cells sometimes enclosed by their own gelatinous envelope. Celk 
 with two cilia of equal length, 2-6 contractile vacuoles, one nucleus. 
 
 7 
 
98 
 
 WISCONSIN PHYTOPLANKTON 
 
 one eyespot, and a cup-shaped to disciform chloroplast that contains 
 one pyrenoid. Number of cells in a colony varying from 200-22,000. 
 
 Asexual reproductive cells few in number (rarely more than 20) and 
 forming autocolonies by repeated division, the young colonies migrat- 
 ing to the center of the coenobe at a certain stage in their development. 
 
 Sexual reproduction heterogamous, monoecious or dioecious, with a 
 development of 6-400 cells into spherical oospheres and few or many 
 of the cells into antheridia that contain 16-256 biciliate fusiform anther- 
 ozoids. Zygote with a smooth or stellate wall. 
 
 KEY TO THE SPECIES. 
 
 Cells with cytoplasmic connections. 
 
 Cytoplasmic connections heavy V. Globator 
 
 Cytoplasmic connections delicate V. Aureus 
 
 Cells without cytoplasmic connections V. Mononae 
 
 VOLVOX GLOBATOR L. PI. 18, Figs. 3-5. 
 
 Systema natura, Ed. 10: 820. 1758; Cohn, Beitr. z. Biol. d. Pflanzen 1, Heft 3: 
 93, vl. 2, -figs. 1-6. 1875. 
 
 'Colonies large, with many (1,000-22,000) cells that are flattened and 
 pentagonal to octagonal in surface view. Cells connected to one an- 
 other by stout cytoplasmic strands. Chloroplast of cells single, flat- 
 tened and angular, with one pyrenoid. Cells with 2-6 contractile vacu- 
 oles at the base of the two cilia and with an eyespot. Gelatinous sheaths 
 of individual cells sharply defined and (in surface view) pentagonal 
 to octagonal by mutual compression. Generally with 8 asexual repro- 
 ductive cells giving rise to autocolonies. Colonies commonly monoe- 
 cious, with 12-40 (generally 20-30) oospheres enclosed by large gelat- 
 inous vesicles. Antherids a flat plate of 64-256 fusiform antherozoids 
 with laterally attached cilia. Zygote verrucose, with conical warts. 
 ( Tychoplanktont) . 
 
 Cells 2-7.5 (generally 3-5) /a in diam. Colonies 400-800 ^ in diam. 
 
 Center (s). Hooker (rr), Kegonsa (rr), Monona (r). Soft (rrr), Wauhesa 
 (rrr). 
 
 VoLvox AUREUS Ehrenberg. PI. 18, Fig. 2. 
 
 Die Infusionsthierchen 71, pi. 4, fig. 2. 1838; Klein, Jarhb. f. wiss. Bot. 20: 
 138, pi. 12, figs. 26-33. 1889. 
 
 Colonies spherical, containing a comparatively small (200-4,000) 
 number of cells. Cells circular in surface view, connected with one 
 another by very fine cytoplasmic strands. Individual gelatinous sheaths 
 of cells confluent with the colonial envelope. Cells containing a spheri- 
 
WISCONSIN PHYTOPLANKTON 
 
 99 
 
 eal chloroplast, one eyespot, and a pair of contractile vacuoles at the 
 base of the two cilia. 4-14 asexual reproductive cells giving rise to 
 autocolonies. Colonies generally dioecious, with 3-9 oospheres and 
 about half of the cells developing into antherids that contain 16-32 
 fusiform antherozoids with two terminal cilia. Zygote smooth-walled. 
 (Facultative Planktont). 
 
 Cells 5-9 fi in diam. ; colonies 200-680 in diam. 
 
 Beaverdam (rrr), Camp (sss), Center (ss), Delavan (ss), Eagle (rr), Eliza- 
 beth (rrr), Fowler (rrr), Jennie (rrr), Kawaguesaga (rrr), Lac du Flam- 
 beau (rr). Lac la Belle (rr). Mill (rrr), Oconomowoc (rrr). Paddock (r), 
 Pokegama (1) (rr), St. Croix (rrr). Silver (2) (rr). 
 
 ' Volvox mononae sp. nov. PI. 18, Fig. 1. 
 
 Colonies spherical, containing a comparatively small (400-2500) 
 number of cells. Cells spherical, not connected with one another by 
 cytoplasmic processes. Individual sheaths of cells confluent with colon- 
 ial envelope. Cells containing a single bell-shaped chloroplast with 
 one pyrenoid, an eye spot, and two cilia whose length is 2-3 times the 
 diameter of the cell. 3-10 asexual colonies formed inside the coeno- 
 bium and these daughter colonies in turn frequently containing young 
 colonies. Asexual reproductive cells becoming much larger than vege- 
 tative cells before division commences. Colonies dioecious, with oogonia 
 and antheridia in young daughter colonies only. 20-60 cells of a 
 young colony formng typical Volvox antheridia that generally contain 
 64 antherozoids. Female colonies with 6-10 oospheres. Zygote smooth 
 walled. 
 
 Vegetative cells 5-8 /x in diam. Colonies 50-350 /x in diam. 
 
 Monona (aaa). 
 
 Order PROTOCOCCALES. 
 
 Vegetative cells immobile; free-floating, sessile, or epiphytic; solitary 
 or in colonies. Colonies amorphous and frequently embedded in a 
 gelatinous envelope ; or of deflnite shape and with or without a gelati- 
 envelope. Colonies capable or incapable of increasing the number of 
 their cells after they are formed. Cells variously shaped, generally 
 with one chloroplast and pyrenoid. 
 
 Asexual reproduction by zoospores, fragmentation of the colony, auto- 
 spores, or autocolonies. Resting akinetes known in some species. 
 
 Sexual reproduction by isogamous zoogametes known but not found 
 in a majority of the genera. 
 
100 
 
 WI8C0N8IN PHYTOPLANKTON 
 
 KEY TO THE FAMILIES. 
 
 Asexual reproduction by zoospores. 
 
 Cells epiphytic or endophytic Planospobaceiab 
 
 Cells or colonies free-floating. 
 
 Colonies capable of growth by cell division Palmeuaceae 
 
 Colonies incapable of growth by cell division Hydeodictyaceai: 
 
 Asexual reproduction by autospores or division of cells. 
 
 Cells capable of vegetative division. 
 
 Solitary, in regular masses, or in strata Pbotoooccaceae 
 
 In colonies held together by remains of old cell walls . . Dictyosphaeriaceae 
 Cells incapable of division except to form autospores Autospoeaceak 
 
 Family PALMELLACEAE. 
 
 Cells spherical, ovoid, or reniform; rarely solitary, generally united 
 to form colonies which are at times of macroscopic size. Colonies al- 
 ways embedded in a gelatinous matrix. Colonies capable of an in- 
 crease in size by the vegetative division of the constituent cells. Chloro- 
 plasts generally single, cup-to disc-shaped and parietal ; or star-shaped 
 and central ; with or without pyrenoids. 
 
 Keproduction by the fragmentation of the colony or by zoospores. 
 
 Sexual reproduction known in certain genera. 
 
 KEY TO THE GENERA. 
 
 Chloroplast star-shaped and central Asterococcus 
 
 Chloroplast cup- to disc-shaped and parietal. 
 
 Cells with pseudocilia Teteaspoea 
 
 Cells without pseudocilia. 
 
 Gelatinous envelope of colony lamellated Gloeocystis 
 
 Gelatinous envelope of colony homogeneous. 
 
 Cells spherical. 
 
 Chloroplast of old cells cup-shaped Sphaerocystis 
 
 Chloroplast of old cells disciform Planktosphaeeia 
 
 Cells ovoid to reniform Gloeooystopsis 
 
 GLOEOCYSTIS Nageli 1849. 
 
 Cells spherical; solitary or in small colonies of eight cells or less. 
 Each cell and the whole colony surrounded by a hyaline, lamellated, 
 gelatinous sheath. Chloroplast of young cells cup -shaped, parietal, and 
 with one pyrenoid; generally diffuse and rich in starch in old cells. 
 
 Asexual reproduction by a fragmentation of the colony through the 
 softening of the gelatinous envelope, or by zoospores. Akinetes known. 
 
WISCONSIN PHYTOPLANKTON 
 
 101 
 
 Gloeocystis gigas (Kiitzing) Lagerheim. PL 19, Fig. 2. 
 
 ofvers. kgl. Vet-Ak. Fork. 40: No. 3: 63. 1883; G. S. West, Brit. Freshw. 
 Algae 245; figs. 113f-H3h. 1904. 
 
 Cells spherical; solitary or in families of 2-8; enclosed by a thick, 
 distinctly lamellated, gelatinous envelope. Chloroplast of young cells 
 cup-shaped, of older cells diffuse. (Tyehoplanktont). 
 
 Cells 9-17 /A in diam. ; colonies 45-95 /jl in diam. 
 
 Mendota (rr), Oconomowoc (rr). 
 
 SPHAEROCYSTIS Chodat 1897. 
 
 Colonies spherical with the cells in groups of 4-8-16-32 and disposed 
 towards the periphery of a hyaline, homogeneous, gelatinous envelope 
 and with the envelope surrounding each group of cells distinct or con- 
 fluent with the colonial envelope. Colonies sometimes forming palmella 
 stages where the cells are irregularly disposed. Cells spherical ; chloro- 
 plast cup-shaped or filling the entire cell, with one pyrenoid. 
 
 Reproduction by the liberation of a group of cells through the soften- 
 ing of the colonial envelope. Zoospores of two sizes have been observed, 
 
 Sphaerocystis Schroeteri Chodat. PI. 19, Figs. S-4. 
 
 Bull. Herb. Boiss. 5: 119, ph 9, figs. 1-12. 1897; G. <S. West, Jour. Linn. Soc. 
 Bot. 39: 76, figs. 9a-9f. 1909. 
 
 Characters the same as those of the genus. (Euplanktont). 
 
 Diam. cells 6-22 ^ ; diam. colonies 50-500 fi. 
 
 Balsam (rr), Bear (2) (ss), Bear Trap (sss), Beasley (rr). Big (sss). Big 
 Butternut (rr), Birch (1) (rr), Birch (2) (ss), Birch Island (rr), Boulder 
 (ss), Browns (rr). Camp (rr), Carson (rr). Catfish (rr). Center (rr), Chetac 
 (ss), Chetek (cc). Clam (rrr). Clear Crooked (s). Crab (r). Cranberry (rr). 
 Deer (rr). Devils (1) (sss). Eagle (rr). East (rr), Elizabeth (sss). Found (r) 
 Fowler (rr), Green (1) (rr). Half Moon (rr), Hillman (rr). Hooker (rr), 
 Kimball (rr). Kitten (rr). Lac Court Oreilles (rr). Lac du Flambeau (r). 
 Lac la Belle (ss). Little Bass (1) (ss). Little Butternut (r). Little Doctor 
 (rr). Little Wood (rr). Long (1) (ss). Long (2) (rr), Long (3) (rrr). Love- 
 less (rr). Lower Nashotah (rr). Lower Nemahbin (cc). Lower Turtle (r), 
 Mary (ss), Mendota (r), Meta (ccc). Mill (sss), Monona (r). Mud (1) (rr), 
 Mudhen (sss), Nicaboyne (r). No Mans (rr). North Turtle (rr). North Twin 
 (rr). Number One (cc), Oconomowoc (ss), Okauchee (ss). Old Taylors (rr). 
 Pike (rr). Pine (2) (rr). Pine Tree (rr), Pokegama (1) (ss), Pokegama (3) 
 (sss). Poplar (ss). Prairie (ss). Rainbow (rr), Rice (1) (ss). Rock (r). 
 Round (1) (rrr). Round (2) (rr), Rudolph (rr). Sand (3) (rr). Sand (4) 
 (rrr). Shell (ccc). Silver (2) (r). South Turtle (r). Tamarack (rr). Upper 
 Nemahbin (rr). Upper Turtle (rr), Waubesa (rr), Winnebago (r). 
 
102 
 
 WISCONSIN PHYTOPLANKTON 
 
 Lemmermann follows Wille in placing the alga as a synonym of 
 Braun’s old genus Gloeococcus but I prefer to follow G. S. West’s 
 practice and consider the two genera distinct. The ordinary vegetative 
 condition is easily recognized but the rather rare palmella stage may be 
 mistaken for one of the limnetic Tetraspora species. 
 
 TETRASPOBA Link 1809. 
 
 Colonies macroscopic or microscopic ; attached or free-floating ; gelat- 
 inous ; spherical, cylindrical, expanded, or variously lobed. Cells spher- 
 ical, generally in groups of four towards the periphery of the homo- 
 geneous, hyaline, gelatinous colonial envelope. Sometimes irregularly 
 distributed within the gelatinous colonial envelope. Chloroplast cup- 
 shaped, parietal ; sometimes diffuse ; with one pyrenoid. Each cell with 
 two or four long, hyaline, gelatinous bristles (pseudocilia). 
 
 Asexual reproduction by the direct metamorphosis of vegetative cells 
 into biciliate zoospores. 
 
 Sexual reproduction by a division of vegetative cells to form 4-8 
 bilciliate zoogametes that fuse in pairs. 
 
 Tetraspora lacustris Lemmermann. PI. 19, Figs. 5-6. 
 
 Bot. Cent. 76: 152. 1898; Forschungsbr. a. d. Biol. Stat. zu Plon 7: 118, pi. 1, 
 fig. 13. 189’9. 
 
 Colonies microscopic; spherical, elongate, or irregular in shape; al- 
 ways free-floating. Cells spherical, generally in groups of four and 
 with pseudocilia 6-8 times as long as the diameter of the cell. Chloro- 
 plast single, cup-shaped, and parietal ; with or without pyrenoids. (Eu- 
 planktont). 
 
 Diam. cells 7-10 /x; diam. colonies up to 300 /x. 
 
 Crawling Stone (sss), Fence (rrr), Long (3) (sss), Mud (2) (sss), Pike 
 (rrr). 
 
 Small colonies frequently resemble palmella stages of Sphaerooystis 
 Schroeteri but Tetraspora may be recognized by the pseudocilia. In 
 case of doubt it is always advisable to stain with safranin to bring out 
 the pseudocilia. 
 
 GLOEOCYSTOPSIS G. M. Smith 1916. 
 
 Cells elongate-cylindrical, with rounded ends and more or less curved. 
 Cells aggregated in fours or eights within a homogeneous gelatinous 
 sheath. Colonies spherical to ovoid and composed of an indefinite num- 
 ber of these aggregates. Colony not enclosed by a gelatinous sheath. 
 
WISCONSIN PHYTOPLANKTON 
 
 103 
 
 Chloroplast of young cells single, laminate, parietal, with one pyrenoid ; 
 diffuse in old cells. 
 
 Reproduction, aside from vegetative cell division, unknown. 
 
 Gloeocystopsis limneticus G. M. Smith. PI. 20, Figs. 1-2. 
 
 Bull. Torr. Bot. Cl. 43: 475, pi. 24, fig- 12. 1916. 
 
 Cells 4-6 fji broad, 10-15 fx long. Cell aggregates 25-30 fi in diam. ; 
 colonies up to 125 /a in diam. (Euplanktont). 
 
 Bear Trap (rr), Beaverdam (rrr). Catfish (rr), Harris (rrr). Little Bass 
 (2) (rrr). 
 
 A species that combines the general external morphological character- 
 istics of Gloeocystis and the cell shape of N ephrocytium. 
 
 PLANKTOSPHAERIA G. M. Smith 1918. 
 
 Cells spherical, embedded in a copious, homogeneous, hyaline, gelat- 
 inous envelope. At first solitary, later irregularly distributed within 
 tiie gelatinous envelope. Mature cells with several parietal, polygonal, 
 flattened chloroplasts each of which contains a single pyrenoid. 
 
 Reproduction by liberation of daughter colonies through the breaking 
 down of the gelatinous colonial envelope. 
 
 PLANKTOSPHAERIA GELATINOSA G. M. Smith. PI. 20, FigS. 3-6. 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 627, pi. 10, figs. 8-11. 1918. 
 
 Specific characters as described above. (Euplanktont). 
 
 Diam. cells 4.5-25 fx ; colonies up to 150 fx in diam. 
 
 Browns (rr), Mendota (r). 
 
 The general appearance of the colony suggests SpJiaerocystis 
 Schroeteri but P. gelatinosa differs in the numerous parietal chloroplasts 
 of each cell. 
 
 ASTEROCOCCUS Scherffel 1908. 
 
 Cells spherical or sub-spherical, solitary or in colonies, with a wide, 
 homogeneous or lamellated, gelatinous envelope. Chloroplast single, 
 central, star-shaped, the astral radiations ending in a disc at the cell 
 wall. Pyrenoid single, at the center of the chloroplast. Certain species 
 with two peripheral vacuoles and an eyespot. 
 
 Asexual reproduction by vegetative cell division and biciliate sub- 
 spherical zoospores. 
 
 Sexual reproduction unknown. 
 
104 
 
 WISCONSIN PHYTOPLANKTON 
 
 Asterococcus limneticus G. M. Smith. PI. 20, Figs. 7-10. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 627, vl. 10, figs. 3-6. 1918. 
 
 Colonies spherical, rarely ovoid, of 4-8-16 spherical cells widely 
 separated from one another and lying within a hyaline, homogeneous, 
 gelatinous matrix. Chloroplast single, star-shaped, with 4 or 8 (rarely 
 16) rays coming from a central mass and ending in a disc at the cell 
 wall. Pyrenoid single, at the center of the chloroplast. (Euplanktont). 
 
 Diam. cells 7.5-35 /a; colonies up to 125 /a in diam. 
 
 Chain (r), Clam (sss). Crooked (rrr). Deer (rrr), Des Moines (rr). Dummy 
 (ss). Fish (sss). Half Moon (rr), Hillman (rrr). Horseshoe (1) (ss), Horse- 
 shoe (2) (rr), Howey (rr). Lac Court Oreilles (ss). Lake of the Woods (rr), 
 Long (1) (r), Nancy (r). North Twin (rrr), Owen (cc). Reserve (r), Rooney 
 (rr). Sand (1) (r). Sand (3) (r), Shell (cc), Whitefish (sss). Wild Goose 
 (rrr). 
 
 The shape and cellular arrangement in colonies of this species is 
 quite similar to that of Sphaerocystis, but a sharp distinction exists in 
 its star-shaped chloroplast, a type of chloroplast that is very uncommon. 
 The alga is widely distributed in the lakes of northwestern Wisconsin. 
 
 Family DICTYOSPHAERIACEAE. 
 
 Cells in spherical or ovoid colonies, the number in young colonies a 
 multiple of two, in older colonies indefinite. Colonies with or without 
 a gelatinous envelope. Cells held together in fours or eights by the 
 persistence of the old mother cell wall in repeatedly branching four- 
 armed thongs or irregular threads. Chloroplast single; cup-shaped, 
 or filling the entire cell ; with one pyrenoid. 
 
 Keproduction by the division of cells into autospores which remain 
 attached to mother colony until accidentally broken away. 
 
 KEY TO THE GENERA. 
 
 Colony enclosed in a gelatinous sheath Dictyosphaebium 
 
 Colony not enclosed in a gelatinous sheath. 
 
 Cells spherical Westella 
 
 Cells ovoid to reniform Dimobphococcus 
 
 DICTYOSPHAERIUM Nageli 1849. 
 
 Cells spherical, ovoid, or reniform, connected with one another by 
 cruciately or dichotomously branching threads. Colony enclosed by a 
 hyaline, homogeneous, gelatinous envelope that is spherical or ovoid in 
 shape. Chloroplast single, parietal, cup-shaped, with one pyrenoid. 
 
WISCONSIN PHYTOPLANKTON 
 
 105 
 
 Eeproduction by tbe division of the cell into 2 or 4 daughter cells 
 which remain connected to the colony by the old mother cell wall that 
 divides into 2 or 4 parts to form the branching thread system connect- 
 ing the cells. Zoospores reported but their existence is very doubtful. 
 Resting akinetes known. 
 
 KEY TO THE SPECIES. 
 
 Mature cells ovoid D. Ehrenbergianum 
 
 Mature cells spherical D. Ptjlchellxjm 
 
 Dictyosphaerium Ehrenbergianum Nageli. PI. 20, Figs. 11-12. 
 Gatt. einz. Algen, 73, pJ. 2, figs. Ea-ES 1849. 
 
 Colonies spherical to ovoid, rarely containing more than 30 cells. 
 Cells ovoid to ellipsoid when mature. Chloroplasts 1-2, parietal, lami- 
 nate, generally with a single pyrenoid. (Facultative Planktont). 
 
 Cells 4-7 jw. broad ; 6-10 ja long. 
 
 Clear (rr), Kegonsa (rrr>. Mendota (rr). 
 
 Dictyosphaerium pulchellum Wood. PI. 20, Fig. 13; PI. 21, Fig. 1. 
 Smithsonian cont. to knowl. 19 , No. 241 : 84, pZ. 10, fig. 4. 1872. 
 
 Colonies spherical to broadly ovoid, of 4-8-16-32 or many cells lying 
 near the periphery of the hyaline, homogeneous, gelatinous envelope. 
 Cells spherical when mature, spherical to ovoid when young ; generally 
 in fours at the ends of a repeatedly branching system of threads. Chloro- 
 plast single, parietal, cup-shaped, with one pyrenoid. (Facultative 
 pJanktont). 
 
 Diam. cells 3-10 /t. 
 
 Amicoy (ss). Balsam (rrr). Bear (1) (ss). Bear (2) (r), Bettine (s). Big 
 Butternut (r), Birch (1) (r), Birch (2) (rrr), Blake (ss). Bone (r), Boulder 
 (rrr). Canteen (rr), Carson (sss). Catfish (r), Catherine (rrr). Center (r). 
 Chain (rr), Chetac (ss), Chetek (ss). Crab (s). Cranberry (rr). Crawling 
 Stone (rrr). Deer (rr), Diamond (rr). Duck (cc). Dummy (sss). Eagle (rr), 
 Elizabeth (rrr), Pishtrap (rr). Granite (ss). Grassy (rr). Grindstone (rr). 
 Half Moon (rr). High (rr), Hillman (ss). Horse (rr). Horseshoe (1) (rrr). 
 Horseshoe (2) (ss), Howey (rr), Jag (rr), Kawaguesaga (rr), Kegonsa (r). 
 Kitten (rrr). Lac Court Oreilles (ss). Lac du Flambeau (rr), Lindy (rr). 
 Little Bass (1) (rr), Little Bass (2) (rr). Little Butternut (rr). Little Crooked 
 (rrr). Little Bice (2) (sss). Little Wood (sss). Long (1) (rrr). Long (3) 
 (rrr). Loon (r). Loveless (rr). Lower Turtle (r). Lynx (rrr), Mendota (ss), 
 Mercer (rrr), Middle McKenzie (rrr), Monona (ss). Mud (2) (rr), Mudhen 
 (rr), Nagawicka (rrr), Nancy (r), Nicaboyne (rr). North Turtle (r), Ocono- 
 mowoc (r), Okauchee (rr). Old Taylors (rr), Owen (rrr). Palmer (rr), Pe- 
 waukee (rr). Pine Tree (sss), Pokegama (1) (r), Pokegama (3) (c). Poor 
 
106 
 
 WISCONSIN PHYTOPLANKTON 
 
 Farm (rrr), Prairie (c), Reserve (rr), Rice (ss), Rock (rr), Rooney (rr), 
 Rose (sss), Rozen (rr), St. Croix (rrr), Sand (3) (rrr). Shell (cc), Sishe- 
 bogema (rr), (South Turtle (rr). Spirit (r). Tamarack (sss). Tenderfoot (rr). 
 Tied Canoe (rrr), Travis (rr). Upper Nashotah (sss). Upper Nemahbin (rr). 
 Vermilion (r), Wapagossett (rrr), Waubesa (ss). White Ash (sss), Whitefish 
 (rr). White Sand (rr), Wild Goose (s), Winnebago (sss). 
 
 DIMORPHOCOCCUS A. Braun 1855. 
 
 Ceils in groups of four and held in an irregular free-floating colony 
 by the branching remains of the old mother cell wall. Colony not en- 
 closed by a gelatinous envelope. Each aggregate of four cells lying in 
 one plane with two cells ovoid to cylindrical with rounded ends, and two 
 cells reniform to cardioid. Chloroplast of young cells single, parietal, 
 laminate, with one pyrenoid; chloroplast of old cells occupying the 
 entire cell. 
 
 Reproduction by the division of any cell into four daughter cells 
 which remain attached to the colony by the threadlike remains of old 
 cell wall until accidentally broken away. 
 
 Dimorphococcus lunatus a. Braun. PI. 21, Fig. 5. 
 
 Alg. Unicell. 44. 1855; Rabenhorst, FI. Bur. Algarum 3: 3G, figs, a-c (p. 6). 
 
 1868; G. S. West, Brit. Freshw. Algae 221, figs. 93a-93b. 1904. 
 
 Cells of each group of four alternately arranged (in vertical view) 
 the central cells cylindrical with rounded ends, the terminal cells reni- 
 form to cardioid. (Facultative planktont). 
 
 Cells 4-15 fi broad, 9-25 /x long. Colonies up to 150 /x in diam. 
 
 Bear (2) (rr). Bear (3) (rr), Beaver dam (rrr), Blue Gill (rrr), Catfish 
 (rr), Des Moines (rrr). Devils (2) (rr). Horseshoe (1) (rr), Horseshoe (2) 
 (rrr), Kegonsa (rrr), Lindy (rr), Minocqua (rrr). Mud (1) (rr), Pike (rr), 
 Pine (1) (rr). Pine Tree (rrr), St. Croix (rrr). Shell (rrr). 
 
 WESTELLA de Wildeman 1897. 
 
 Cells small, spherical to sub-spherical, grouped in fours (rarely 
 eights) in irregular, free-floating colonies containing 30-100 cells; the 
 colony being held together by the non-gelatinizing remains of the old 
 mother cell walls. Colonies without a gelatinous envelope. Chloro- 
 plast cup-shaped and parietal, or entirely filling the cell, with or with- 
 out a pyrenoid. 
 
 Reproduction by the division of any cell to form 4^S autospores that 
 remain connected with the mother colony until accidentally broken 
 away. 
 
WISCONSIN PHYTOPLANKTON 
 
 107 
 
 KEY TO THE SPECIES. 
 
 Groups with cells quadrate or pyramidate W. Botryoides 
 
 Groups with cells in a linear series W. Linearis 
 
 Westella botryoides (W. West) de Wildeman. PL 21, Fig. 4. 
 Bull. Herb. Boiss. 5: 532. 1897. 
 
 Tetracoccus 'botryoides W. West, Jour. Roy. Micr. Soc. 1892: 735, pi. 10, 
 ags. 43-48. 1892. 
 
 Colonies irregularly shaped, without a gelatinous envelope, generally 
 containing 40-80 cells. Cells spherical, pyramidately or quadrately 
 arranged in groups of four (rarely eight). Chloroplast single, cup- 
 shaped or entirely filling the cell; with or without a pyrenoid. (Facul- 
 tative Planktont). 
 
 Diam. cells 3-9 /a. 
 
 Blake (rrr), Fishtrap (rr), Hillman (rrr), Horse (rrr), Horseshoe (1) (rr), 
 Jag (r), Little Bass (2) (rr), Little Butternut (rrr). Little Crooked (rr), 
 Mendota (rrr). Mill (rrr), Nancy (rr). Pine Tree (rr). Round (3) (rr), 
 Sishebogema (rr). 
 
 var. MAJOR G. M. Smith. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 628. 1918. 
 
 Cells larger than the typical form, otherwise the same. 
 
 Diam. cells 8-13 /a. 
 
 Whitefish (rr). 
 
 Westella linearis sp. nov. PI. 21, Figs. 2-3. 
 
 Colonies of irregular shape, rarely containing more than 40 cells. 
 Cells spherical, always in groups of four and arranged in a linear 
 series. Kemains of old mother cell walls that hold the colony together 
 very inconspicuous. Colony without a gelatinous envelope. Chloro- 
 plast single, parietal, without a pyrenoid. (Euplanktont ?). 
 
 Diam. cells 3-6 /a. 
 
 Pine Tree (rr). 
 
 In the arrangement of the cells this species is quite unlike the other 
 members of the genus but since the cells are in groups of four that are 
 held together by the remains of old mother cell walls it seems better 
 to place it in this genus than in Crucigenia. 
 
108 
 
 WISCONSIN PHYTOPLANKTON 
 
 Family PROTOCOCCACEAE. 
 
 Cells solitary and spherical; or in colonies containing an indefinite 
 number of cells that are spherical and mutually compressed or in very 
 short irregular filaments. Cell wall delicate to heavy, smooth or vari- 
 ously sculptured. Chloroplast single, parietal and disciform, with or 
 without pyrenoids. Cells capable of vegetative division. 
 
 Reproduction, aside from vegetative division of cells, by zoospores or 
 aplanospores. 
 
 KEY TO THE GENERA. 
 
 Cell wall thin, smooth Chlorella 
 
 Cell wall thick, sculptured Teochiscia 
 
 CHLORELLA Beyerinck 1890. 
 
 Cells small, spherical ; solitary or in small colonies of indefinite shape. 
 Chloroplast disciform to cup-shaped, with or without a pyrenoid. 
 
 Reproduction by the division of cell contents into 2-4-8 daughter 
 cells. Resting akinetes known. 
 
 Chlorella vulgaris Beyerinck. PI. 22, Fig. 1. 
 
 Bot. Ztg. 48: 758, pi. 7, figs. 2a-2b. 18'90. 
 
 Cells spherical, generally solitary. Chloroplast parietal, cup-shaped, 
 with or without a pyrenoid. Cell wall smooth and delicate. (Faculta- 
 tive Planktont). 
 
 Diam. cells 5-10 /a. 
 
 Mendota (rr). 
 
 C. vulgaris is a minute alga and one that is easily overlooked. The 
 record of its occurrence in Lake Mendota is based upon its isolation by 
 pure culture methods from a plankton catch. It is very probable that 
 it is present in other lakes but has been overlooked. 
 
 TROCHISCIA. Kiitznig 1845. 
 
 Cells spherical to sub-spherical, solitary or in small clumps. Cell 
 wall fairly heavy, areolate or ornamented vdth spines, denticulations, 
 ridges, or other projections. Cells generally containing several parietal 
 disciform chloroplasts each with a pyrenoid. 
 
 Reproduction by vegetative cell division or the formation of -4-16 
 aplanospores that are liberated by the dissolution of the old mother 
 cell wall. 
 
WISCONSIN PHYTOPLANKTON 
 
 109 
 
 Trochiscia reticularis (Reinscli) Hansgirg. PI. 22, Fig. 2. 
 Hedwigia 27: 129. 1888. 
 
 Acanthococcyiis reticularis Reinsch, Ber. d. D. bot. Ges, 4: 242, pZ. 12, figs. 
 24a-24b. 1886. 
 
 Cells generally solitary, spherical. Cell wall fairly thick and covered 
 with linear ridges that intersect to form 50-70 polygons on the surface 
 of the cell. (Tychoplanktont). 
 
 Diam. cells 24-32 /x. 
 
 Wildcat (rrr). 
 
 Family AUTOSFOEACEAE. 
 
 Cells solitary or in colonies that are generally of a definite shape and 
 without a gelatinous envelope. Cells variously shaped; with a single 
 chloroplast and pyrenoid as a rule. Cells incapable of vegetative divi- 
 sion to form two similar daughter cells. 
 
 Reproduction by division of cell contents into 2-4r-8-l 6-32-64 cells 
 which assume the shape of the mother cell before their liberation (auto- 
 spores). In the colonial species the autospores from any one cell are 
 organized to form the new colony (autocolony) before their liberation. 
 Motile asexual reproductive bodies or sexual reproduction unknown. 
 
 KEY TO THE SUBFAMILIES. 
 
 Cells solitary. 
 
 Cells angular Tetraedreae 
 
 Cells not angular. 
 
 Ornamented with long spines or setae Micractinieae (p. p.) 
 
 Not ornamented with spines or setae. 
 
 Length of cells several times the diameter Selenastreae (p. p.) 
 
 Length of cells not more than twice the diameter Oocysteae (p. p.) 
 
 Cells in colonies. 
 
 Ornamented with long setae or spines. 
 
 Coenohe capable of growth in three directions Micractinieae (p. p.) 
 
 Coenobe a flat plate Crucigenieae (p. p.) 
 
 Not ornamented with setae or spines. 
 
 Number of cells in coenobe always a multiple of two. 
 
 Coenobe flat Crucigenieae (p. p ) 
 
 Coenobe spherical or cells radiating from a common 
 
 center > Coelastreak 
 
 Number of cells not a multiple of two in every case. 
 
 Cells elongate, straight or curved Selenastreae (p. p.) 
 
 Cells spherical, ovoid, or reniform Oocysteae (p. p.) 
 
110 
 
 WISCONSIN PHYTOPLANKTON 
 
 Subfamily OOCYSTEAE, 
 
 Cells spherical, ovoid, or renif orm ; solitary or in temporary colonies. 
 Daughter cells retained within old mother cell wall for some time after 
 their formation. Walls generally thick and cells with one to many 
 chloroplasts. 
 
 KEY TO THE GENERA. 
 
 Cells within old mother cell wall separated by a dark gelatinous 
 
 mass Gloeotaenium 
 
 Cells within old mother ceil wall not separated by a dark gelat- 
 inous mass. 
 
 Cells ovoid to elliptic, never curved Oocystis 
 
 Cells ovoid to reniform, frequently curved Nepheooytium 
 
 OOCYSTIS Nageli 1845. 
 
 Cells ovoid, ellipsoid, or cylindrical with rounded to somewhat pointed 
 ends, generally symmetrical but never curved. Cell wall smooth, with- 
 out spines, frequently with nodular thickenings at the poles. Chloro- 
 plasts one to many; parietal, disciform, stellate, or reticulate; with or 
 without pyrenoids. Cells solitary or in temporary colonies of 2-4-8-16 
 or more enclosed by the partially gelatinized and greatly swollen old 
 mother cell wall. 
 
 Reproduction by a formation of 2-4^8-16 autospores that remain 
 within the old cell wall for some time. Three to four cell generations 
 sometimes enclosed by the same wall. Tetraedron-YAiQ resting spores 
 with granulate walls have been observed. 
 
 The genus differs from others in the expanded cell wall that encloses 
 the cells in temporary colonies. Printz (Nyt. Mag. f. Naturvidensk. 
 1913, p. 165) has recently monographed the genus and cleared up many 
 points by collecting the published descriptions of species; but there is 
 great need of a series of cultural studies to determine the range of 
 variation within the so-called “species” that are recognized at the 
 present time. 
 
 KEY TO THE SPECIES. 
 
 Cbloroplast stellate O. Natans 
 
 Cbloroplast disciform to laminate. 
 
 Cells with polar nodules. 
 
 Sides of cells concave O. Pandubifobmis 
 
 Sides of cells convex. 
 
 4 or more chloroplasts in each cell. 
 
 Cells with 40-60 chloroplasts O. Ebemosphaebia 
 
WISCONSIN PHYTOPLANKTON 
 
 111 
 
 Cells with 6-25 chloroplasts. 
 
 Polar nodules conspicuous, 12-25 chloroplasts O. Solitaria 
 
 Polar nodules not prominent, 4-10 chloroplasts O. Crassa 
 
 1-2 (rarely 4) chloroplasts in each cell. 
 
 Cells elliptic, length ll^ times breadth O. Lacustris 
 
 Cells oblong-cylindrical, length 2-3 times breadth O. Submaeina 
 
 Cells without polar nodules. 
 
 Poles of cells rounded. 
 
 Length of cells less than 12 /x O. Pusilla 
 
 Length of cells more than 12 /x. 
 
 1-4 chloroplasts in each cell O. Bobgei 
 
 8-10 chloroplasts in each cell O. Elliptica 
 
 Poles of cells pointed. 
 
 Old cell wall enclosing colonies rounded 0. Parva 
 
 Old cell wall enclosing colony sharply pointed.. 0. Gloeocystiformis 
 
 OocYSTis PusiLLA Hansgirg. PL 22, Fig. 3. 
 
 Sitzbr. d. k. bohm. Ges. d. Wiss. in Prag, Jahrgang 1890: 9. 1890; Printz, Nyt. 
 Mag. f. Naturvidensk. 51: 181, pi. 4, figs. 31-32. 1913. 
 
 Cells cylindrical, poles rounded and without nodules. Chloroplasts 
 2-3, parietal, laminate, without pyrenoids. Temporary colonies con- 
 taining 2-^L-8 cells. (Tychoplanktont). 
 
 Diam. cells 4. 5-6. 5 /x ; length 8-12 fx. 
 
 Tied Canoe (rr). 
 
 OocYSTis Borgei Snow. PL 22, Fig. 4. 
 
 Bull. U. S. Fish Comm. 22: 379, pi. 2, figs. VIP-VIP. 1903. 
 
 Cells broadly elliptic, length 1% times the breadth; poles rounded 
 but without nodules. Chloroplasts 1^, parietal, laminate, each con- 
 taining a single pyrenoid. Cells solitary or in families of 2-4-8 within 
 an old mother cell wall. (Euplanktont). 
 
 Cells 9-13 broad, 9-17 fi long. 
 
 Big (rr), Birch (1) (sss). Camp (r), Catfish (r). Devils (1) (rr). Duck 
 (r). Found (rr). Green (2) (rr), Kawaguesaga (rr). Kitten (rrr). Long (2) 
 (rr), Mendota (r). North Turtle (r), Pardee (rr). Rock (r), Winnebago (rr). 
 
 OocYSTis ELLIPTICA W. West. PL 22, Pig. 5. 
 
 Jour. Roy. Micr. Soc. 1892: 736, pi. 10, fig. 56. 1892. 
 
 Cells oblong-elliptic, with poles rounded and without nodules. Chlor- 
 oplasts 10-20, disciform, parietal, without ( ?) pyrenoids. Cells rarely 
 solitary, generally in families of 4-8 within an old mother cell wall. 
 ( Tychoplanktont) . 
 
 Cells 11-12.5 /X broad, 20-25 /x long. 
 
 Amicoy (rr). 
 
112 
 
 WISCONSIN PHYTOPLANKTON 
 
 OocYSTis PARVA W. & G. S. West. PL 22, Fig. 6. 
 
 Jour, of Bot. 36: 335. 1898; G. S. West, ibid. 37: 223, pi. 394, iigs. 14-17. 1899. 
 
 Cells broadly fusiform to elliptic, ends pointed but without polar 
 nodules. Each cell with 1-3 parietal, laminate to disciform chloro^ 
 plasts, with or without pyrenoids. Cells solitary or in families of 2-^r-8. 
 (Facultative Planktont). 
 
 Cells 4-7 ft broad ; 6-12 ft long. 
 
 Beaver (1) (rr), Bettine (rr). Clear Crooked (rr), Cochrane (rrr). Crab 
 (rrr). Deer (rr), George (rr). Half Moon (rr). Hooker (rr). Little Bass (2) 
 (rr). Lynx (rr), Mendota (rr), Muskallonge (rr). Palmer (rr), Pine (1) (rr), 
 Rudolph (rr). Sand (1) (rrr). Stone (rr), Wolf (rr). 
 
 OocYSTis GLOEOCYSTiFORMis Borge. PL 22, Fig. 7. 
 
 Botaniska Studier till. F. R. Kjellman 23, pi. 1, figs, la- lb. 1906. 
 
 Cells narrowly elliptic with ends pointed. Chloroplast single, pari- 
 etal, without a pyrenoid. Cells in families of 2-4 within the old cell 
 wall, several cell generations frequently forming a single colony. Wall 
 enclosing colony with pointed ends but no polar nodules. (Tychoplank- 
 tont). 
 
 Breadth of cell 3-5.5 ft ; length 8-15 ft. 
 
 Lac Court Oreilles (sss). 
 
 The old mother cell wall does not gelatinize as readily in this species 
 as in others so that several cell generations are generally found in the 
 same colony. The species is best recognized, however, by the sharply 
 pointed ends of the colony waU. 
 
 OocYSTis LAcuSTRis Chodat. PL 22, Figs. 8-9. 
 
 Bull. Herb. Boiss. 5: 119, pi. 10, figs. 1-7. 1897. 
 
 Cells elliptic to broadly fusiform, somewhat pointed and with a 
 nodule at the poles. Chloroplasts 1-3, laminate, parietal, with or with- 
 out pyrenoids. Margins of chloroplasts sometimes irregular. Cells 
 rarely solitary, generally in families of 2-4-8 within the old mother 
 cell wall. (Euplanktont). 
 
 Cells 8-22 fi broad, 14-32 ft long. 
 
 Big Butternut (rr), Bone (rr). Center (r). Chain (rr), Chetek (r). Devils 
 (2) (ss). Dummy (rr), Fowler (rr), Hillman (rr), Little Bass (2) (rr). 
 Little Butternut (rrr). Long (2) (rrr), Long (3) (rrr), Mary (r), Mercer 
 (rr), Palmer (rr), Pokegama (3) (rr). Prairie (rr), Reserve (rr). Sand (4) 
 (rr), Sishebogema (rrr), Upper Nashotah (rrr), Upper Turtle (sss). White 
 Sand (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 113 
 
 OocYSTis SUBMARINA Lagerheim. PI. 22, Fig. 10. 
 
 Bot. Not. 1886 : 45, iig. 1. 1886. 
 
 Cells oblong-cylindrical, 2-3 times as long as broad, somewhat pointed 
 and with a nodule at each pole. Chloroplasts 1-2, laminate, parietal, 
 usually with a pyrenoid. Cells rarely solitary, generally in families 
 of 2-d^8-16 within the old mother cell wall. (Tychoplanktont). 
 
 Cells 3-9 IX broad, 7-20 /x long. 
 
 Camp (sss), Upper Nemahbin (rr). 
 
 OocYSTis SOLITARIA Wittrock. PL 22, Fig. 11. 
 
 Bot. Not. 1879: 24, figs. 1-5. 1879. 
 
 Cells ovoid to ellipsoid, solitary or in families of 2-4r-8. Cell wall 
 fairly thick and with conspicuous polar nodules. Chloroplasts numer- 
 ous (generally 12-25), parietal, disciform to polygonal, with or with- 
 out pyrenoids. (Facultative Planktont). 
 
 Cells 7-20 /X broad, 14-35 /x long. 
 
 Hooker (r). Sand (1) (rr). 
 
 OocYSTis CRASSA Wittrock. PL 22, Figs. 12-13. 
 
 Bot. Not. 1880: 117. 1880. 
 
 Cells ovoid, length 1% times the breadth, with a nodule at each pole. 
 Chloroplasts 4-10 in number, fairly large, parietal, disciform to angu- 
 lar, generally with a pyrenoid. Cells solitary or in families of 2-4-8. 
 Old cell wall enclosing the colony greatly distended. (Tychoplanktont) . 
 Cells 10-20 /X broad, 11^26 fx long. 
 
 St. Croix (rr). 
 
 OocYSTis EREMOSPHAERiA G. M. Smith. PL 23, Figs. 1-2. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 630, pi. 14, figs. 8-9. 1918. 
 
 Cells ovoid, 1% to 2 times as long as broad. Solitary or in families 
 of 2-4. Chloroplasts numerous (40-60), parietal, lenticular, each con- 
 taining a single pyrenoid. Cell wall thick, with a conspicuous polar 
 nodule. (Facultative Planktont ?). 
 
 Cells 23-31 fx broad, 35-45 /x long. 
 
 Beaverdam (rr). Shell (sss). 
 
 8 
 
114 
 
 WISCONSIN PHYTOPLANKTON 
 
 OocTSTis PANDURiFORMis YSiT. MINOR G. M. Smith. PI. 23, Fig. 3. 
 Bull. Torr. Bot. Cl. 43: 471, pi. 24, fig. 2. 1916. 
 
 Cells oblong-ovoid, 2 to 2% times as long as broad, sides slightly 
 concave and poles with a conspicuous nodule. Chloroplasts numerous 
 (15-25), parietal, disciform, and each containing a pyrenoid. Cells 
 solitary or in families of 2-4r-8. (Tychoplanktont). 
 
 Greatest diameter of cells 12-15 /t, median diameter 11-14; length 
 30-35 
 
 Star (rr). 
 
 This is the only species of the genus where the sides of the cells are 
 concave. 
 
 Oocystis natans var. major var. nov. PI. 23, Figs. 4-5<i 
 
 Cells ovoid, without a conspicuous polar nodule. Chloroplasts 4^8, 
 parietal, star-shaped or irregular, each chloroplast with a pyrenoid. 
 More than two cell generations rarely found within the same mother 
 cell wall. (Facultative Planktont). 
 
 Cells 16-25 broad, 31-38 /a long. Families up to 90x120 fx. 
 
 Birch (2) (sss), Chetac (s). Rice (1) (rr). 
 
 Lemmermann founded the genus Oocystella upon this stellate nature 
 of the chloroplast (Zeits. f. Fischeri u. d. Hilfsw. 11 : 103. 1903) but 
 the genus has not been recognized and the single species is placed in 
 Oocystis. 
 
 NEPHROCYTIUM Nageli 1849. 
 
 Cells ovoid, reniform, or oblong-elliptic; generally in colonies of 
 2-4—8-16 cells within the partially gelatinized remains of the old mother 
 cell wall. Arrangement of cells in young colonies spiral, in old colonies 
 irregular. Chloroplast single and expanded at first, later fragmenting 
 and becoming diffuse ; pyrenoid single. 
 
 Reproduction by the formation of 2-4-8-16 autospores in each cell. 
 
 Nepiirocytium Agardhianum Nageli. PI. 23, Pigs. 6-7. 
 
 Gatt. elnz. Algen 79, pi. 3, figs. Ca-CP. 1849. 
 
 Cells reniform, generally spirally arranged in young colonies. Chlor- 
 oplast single, parietal, laminate, and with one pyrenoid in young cells ; 
 diffuse in old cells. (Tychoplanktont). 
 
 Cells 2-12 fx broad, 6-28 jx long ; colonies up to 60 fx long. 
 
 Bear (3) (rrr). Bear Trap (rrr). Camp (rr), Hillman (rr). Little Bass 
 (rrr), Mendota (rr). Mill (rrr). 
 
WISCONSIN PHYTOPLANKTON 
 
 115 
 
 GLOEOTAENIUM Hansgirg 1890. 
 
 Cells spherical, ovoid, or variously flattened; solitary or united in 
 colonies of 2-4r-8 cells enclosed by a non-expanded mother cell wall and 
 separated from one another by a dark colored gelatinous mass that lies 
 between the cells. Colonies rectangular, with rounded corners in front 
 view ; oblong with sharp corners in side view. Cell wall thick, distinctly 
 lamellated ; old cell wall enclosing the colony frequently with folds and 
 gelatinous discs opposite the cells. Chloroplast entirely Ailing cells; 
 with or without a pyrenoid. 
 
 Reproduction by autospores and aplanospores. 
 
 Gloeotaenium Loitlesbergerianum Hansgirg. PI. 23, Pigs. 8-9. 
 
 Sitzbr. d, k. bohm. Ges. d. Wiss. in Prag, Jabrgang 1890: 10. 1890; Transeau, 
 
 Bot. Gaz. 55: 66, pi. 3, figs. 1-24. 1913. 
 
 Cells spherical to ovoid, completely filling the space inside of old 
 mother cell wall. (Tychoplanktont). 
 
 Diam. cells 20-30 fi; length 2-celled colonies 40-70 fi breadth 22-40 fi; 
 thickness 20-30 /i. 4-celled colonies 40-70 fi broad, 40-80 ^ long. 
 
 Big Butternut (rrr). 
 
 Sub-family TETRAEDREAE. 
 
 Cells always solitary, without a gelatinous envelope, flattened or 
 isodiametric, triangular, quadrangular, or polyangular; angles simple 
 or produced into spines or long hyaline setae. 
 
 KEY TO THE GENERA. 
 
 Cells simple or with fairly stout spines at angles Tetraedron 
 
 Cells with long hyaline setae at angles Polyedbiopsis 
 
 TETRAEDRON Kiitzing 1845. 
 
 Cells solitary, free-floating, flattened or isodiametric, triangular, 
 quadrangular, or polyangular. Angles simple or produced into simple 
 or furcate spines. Cell wall smooth or verrucose. Chloroplasts one to 
 many, parietal, disciform to angular ; or completely filling the cell ; with 
 or without pyrenoids. 
 
 Reproduction by division of cell contents into 1^8 autospores that 
 are liberated by the rupture of the old mother cell wall. 
 
116 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Angles of cells never produced into processes. 
 
 Corners of cells without spines. 
 
 Cells triangular T. Muticum 
 
 Cells quadrangular T. Minimum 
 
 Corners of cells with spines. 
 
 All cell corners in the same plane. 
 
 Cells triangular T. Trigonum 
 
 Cells with more than three angles. 
 
 Cells with four angles T. Reguu\re v. Incus (p. p.) 
 
 Cells with five angles T. Caudatum 
 
 All cell corners not in the same plane. 
 
 Cells quadrangular. 
 
 Pyramidal cells T. Regulabe 
 
 Halves of cells twisted over one another. 
 
 Wall smooth. 
 
 Angles delicately tapering T. Victorieae var. Major 
 
 Angles strongly convex T. Regulars var. Torsum (p. p.) 
 
 Wall verrucose T. Verrucosum 
 
 Cells five-angled T. Pentaedricum 
 
 Angles at corners produced into processes. 
 
 Processes always unbranched T. Hastatum 
 
 Processes always branched. 
 
 Cells flattened and processes in the same plane. 
 
 General outline of cell H-shaped T. Constricum 
 
 General outline of cell not H-shaped. 
 
 Processes long, conspicuously branched T. Gracilb 
 
 Processes short, not conspicuously branched. .. .T. Lobulatum (p. p.) 
 Cells isodiametric and processes not in the same plane. 
 
 Processes short T. Enorme 
 
 Processes long. 
 
 With 3-5 series of branchings T. Lobulatum var. Polyfuroatum 
 
 Never more than three series of branchings. 
 
 Diameter of cells always greater than the length 
 
 of the processes T. Planotonicum 
 
 Diameter of cell always less than the length of 
 
 the processes T. Limneticum 
 
 Tetraedron muticum var. punctulatum (Reinseh) de Toni. PI. 23, 
 
 Figs. 10-13. 
 
 Sylloge algarum 1 : 600. 1889. 
 
 Polyedrium muticum var. punctulatum Reinseh, Notarisia 3: 498, pi. 4, 
 flg. 6. 1888. 
 
 Cells small, triangular, somewhat flattened. Sides of cells convex in 
 front view. Corners sharp but without spines. Cell wall covered with 
 small granules. (Tychoplanktont). 
 
 Diam. cells 15-20 fx; thickness 8-10 /x. 
 
 Beaverdam (rr). Deer (rrr), Sand (2) (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 117 
 
 Tetraedron trigonum (Nageli) Hansgirg. PI. 23, Figs. 14-16. 
 Hedwigia 27: 130. 1888. 
 
 Polyedrium trigonum Nageli, Gatt. einz. Algen 84, pi. 4, ^gs. Bla-Blb. 1849. 
 
 Cells medium sized, triangular, flattened. Sides of cells generally 
 concave, rarely straight. Corners with a single, stout, straight or curved 
 spine. (Facultative Planktont). 
 
 Diam. cells (without spines) 20-30 ix \ length spines 8-10 /x. 
 
 Crawling stone (rrr). High (r), Pokegama (1) (rr). Rice (1) (rrr). Ten- 
 derfoot (rr). Tied Canoe (rrr). 
 
 var. SETiGERUM (Archer) Lemmermann. PI. 24, Figs. 1-4. 
 
 Arkiv. for Botanik 2, No. 2: 110. 1904. 
 
 Tetrapedia setigera Archer, Quart. Jour. Micr. Sci. N. S. 12: 365, pi. 21, 
 figs. 14-17. 1872; Grevillea 1: 46, pi. 3, figs. 14-17. 1872; G. S. West, Brit. 
 Freshw. Algae 349. 1904; de Toni, Sylloge algarum 5: 113. 1907. 
 
 Polyedrium trigonum var. setigerum (Archer) Schroder, Forschungsbr. a. d. 
 Biol. Stat. zu Plon 6: 23, pi. 1, fig. 6. 1898. 
 
 Cells small, triangular, flattened, with a conspicuous emargination 
 on each side in front view. Comers of cells rounded and produced into 
 a long delicately tapering spine. Chloroplast single. Ailing the entire 
 cell ; with one pyrenoid. (Facultative Planktont). 
 
 Diam. cells (without spine) 7-9 /x; length of spines 12-15 /x. 
 
 White Ash (r). 
 
 G. S. West and de Toni follow Archer in considering this organism 
 a member of the Myxophyceae West stating; setigera Archer is a 
 beautiful little species known from N. W. Scotland and W. Ireland, 
 which has been erroneously referred by some authors to the chlorophy- 
 ceous genus Tetraedron. The cell contents of Tetrapedia setigera are 
 homogeneous and of a pale blue-green color.” The cell contents of the 
 individuals that I have observed are distinctly grass green in color 
 and contain a single pyrenoid. This pyrenoid has not been noted 
 by ell her Archer or Schroder. Since the shape and dimensions of 
 the cel's that I have found are exactly the same as those given by 
 Archer I believe that I am dealing with the same organism that he 
 described and one which is a member of the Chlorophyceae and not 
 the Myxophyceae. 
 
 var. GRAciLE (Reinsch) de Toni. PI. 24, Figs. 5-9. 
 
 Sylloge algarum 1: 598, 1889; Printz, Kgl. Norske Vidensk. Selsk. Skr. 1915, 
 No. 4: 29, pi. 3, figs. 167-169. 1916. 
 
 Polyedrium trigonum var. gracile Reinsch, Die Algenfl. d. mitt. Th. v. 
 hh-anken 75: pi. 3, figs, la-lb. 1867. 
 
 Tetraedron proteiforme G. M. Smith non (Turner) Brunnthaler, Trans. Wis. 
 Acad. Sci., Arts, & Lett, 19': 632, pi. 15, figs. 4-5. 1918. 
 
118 
 
 WISCONSIN PHYTOPLANKTON 
 
 Cells triangular, flattened, concavity of sides very marked. Angles 
 of cells ending in short spines. Several parietal, disciform chloroplasts 
 without pyrenoids. (Facultative Planktont). 
 
 Cells 23-50 fx broad ; 6-10 fi thick. 
 
 Blake (rr), Chain (r), Cochrane (r), Fishtrap (rr), Horse (r), Lac Court 
 Oreilles (rr), Little Bear (rr), Little Crooked (rrr). Loon (rr), Paddock (rrr). 
 Palmer (rrr), Rice (1) (rr), Tenderfoot (r). Tied Canoe (rrr). White Ash 
 (rr), Wolf (rr). 
 
 In the second list of Wisconsin algae this alga was given as T. pro- 
 teiforme but I am now convinced that it is T. trigonum var. gracUe. 
 The cells reach a much larger size than that given by Reinsch and the 
 excavation of the sides may be very much greater ; in fact the cells are 
 at times so delicate that they might be placed as Cerasterias species had 
 not other individuals in the same collection the ordinary cell shape of 
 T. trigonum var. gracUe, 
 
 Tetraedron minimum (A. Braun) Hansgirg. PI. 24, Figs. 10-13. 
 Hedwigia 27: 131. 1888; G. S. West, Brit. Freshw. Algae 231, fig. 101a. 1904. 
 
 Cells small, flattened, front view square or oblong with slightly 
 rounded corners and concave sides. Side view fusiform-elliptic. Wall 
 smooth or finely granulate. Chloroplast single, parietal, with one 
 pyrenoid. (Facultative Planktont). 
 
 Cells 6-20 fi long, 5-8 fx thick. 
 
 Beaver (2) (rrr). Camp (rr), Deer (rrr), Hillman (rrr), Horse (rr), Little 
 Bass (2) (rrr). Little Doctor (rr), Mendota (rrr), Okauchee (rrr), Paddock 
 (rrr). Round (3) (rrr). 
 
 Tetraedron regulare Kiitzing. PI. 24, Fig. 14. 
 
 Phycol. germanica 129. 1845. 
 
 Polyedrium tetraedricum Nageli, Gatt. einz. Algen 84, pi. 4, figs. B3a-B3b. 
 1849. 
 
 Cells medium sized, tetragonal, generally pyramidal, sides concave, 
 straight, or slightly convex. Angles with a single, heavy, short, blunt, 
 spine. ( Tychoplanktont ) . 
 
 Diam. cells (with spines) 14-45 fx. 
 
 Blake (rr). 
 
 var. INCUS Teiling. PI. 24, Figs. 15-16. 
 
 Sv. Bot. Tids. 6: 277, 274, fig. 12. 1912. 
 
 Polyedrium regulare Chodat non Kiitzing, Mater, pour la flore crypt. Suisse 
 V: 220, fig. 146. 1902. 
 
 Cells small, tetragonal, flattened or pyramidal, sides slightly concave. 
 Angles produced into a single short delicate straight or curved spine. 
 ( Tychoplanktont) . 
 
WISCONSIN PHYTOPLANKTON 
 
 119 
 
 Diam. cells (without spine) 13-18 /a; length of spines 7-8 /a. 
 
 Poor Farm (rr). 
 
 This is probably what Chodat has figured as T, regulare. It differs 
 from the typical form in the smaller size, constantly concave sides of 
 the cell, and the delicate spines at the cell angles. 
 
 var. TORSUM (Turner) Brunnthaler. PI. 24, Figs. 17-18. 
 in Pascher, Siisswasserfl. Deutschl., osterr. u. d. Schw. 5^: 150, fig. 169. 1915. 
 
 Cells medium sized, tetragonal, with the two halves of the cells 
 cruciately arranged. Sides of cells straight or convex. Angles of cells 
 with a single short stout spine (Facultative Planktont). 
 
 Diam. cells 25-40 /a. 
 
 Horse (sss). 
 
 Over a hundred individuals were observed in the plankton catch 
 from this lake and the twisting of the cell halves was a very constant 
 character. 
 
 Tetraedron victorieae var. major var. nov. PI 24, Figs. 19-22; 
 
 PI. 25, Fig. 1. 
 
 Cells medium sized, four-sided, with two deeply emarginate sides 
 dividing the cell into two cruciately arranged halves. Sides of cells, 
 in vertical view, broadly fusiform with acute apices. All angles of 
 cells with a single heavy straight spine (Euplanktont). 
 
 Cells (with spines) 30-60 /a long; 15-20 /a broad. 
 
 Chain (r). 
 
 The cell shape and the peculiar twisting of the two halves is identical 
 with that of T. victorieae Woloszynska (Hedwigia 55: 203, pi. 6, jigs. 
 1-A:. 1914) which is known from the plankton of Lake Victoria 
 
 Nyanza, Africa. Measurement of about 25 Wisconsin individuals give 
 the following variation in size, length 30-60 /a, breadth 15-20 ; whereas 
 the length of the African individuals varies from 20 to 30 /a and the 
 breadth 10-15 /a. 
 
 Tetraedron verrucosum G. M. Smith. PI. 25, Pigs. 2-3. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 632, pi. 15, figs. 1-2. 1918. 
 
 Cells large, tetragonal, pyramidate, or with the halves cruciate. Sides 
 convex. Angles of cell terminating in a very heavy, blunt spine. Cell 
 wall thick, verrucose. (Euplanktont). 
 
 Diam. cells (with spines) 65-80 /a; length of spines 13-18 /a. 
 
 Bear (1) (rr). 
 
120 
 
 WISCONSIN PHYTOPLANKTON 
 
 Tetraedron caudatum (Corda) Hansgirg. PI. 25, Figs. 4-7. 
 Hedwigia 27: 131. 1888; G. iS. West, Brit. Freshw. Algae 231, fig- 101®. 1904. 
 
 Cells small, flattened, flve-sided; four of the sides concave and the 
 fifth deeply incised. Angles rounded and produced into a single 
 straight spine that lies parallel with the flat side of the cell. (Tycho- 
 planktont) . 
 
 Diam. cells 6-22 fx ; length of spines 1-3.5 /x. 
 
 Ctiain (rrr). East (rrr), Dutchmans (rrr). Horse (rr). Lake of the Woods 
 (rrr), Mendota (rrr), Palmer (rrr). Reserve (rrr). Wild Goose (rrr). 
 
 The notch at one side of the cell varies considerably in depth but 
 is always deeper than the incurving of the other four sides. 
 
 var. LONGispiNUM Lemmermann. PI. 25, Pigs. 8-12. 
 
 Bot. Cent. 76: 151. 1898; Forschungsbr. a. d. Biol. Stat. zu Flon 7: 117, ph 1, 
 figs. 8-9. 1899. 
 
 Spines on corners at right angles to the flat side of the cell, generally 
 two pointing in one direction and three in the other. Spines much 
 longer than in the typical form. (Euplanktont). 
 
 Diam. cells (without spines) 8-18 /a; length of spines 3-8 fi. 
 
 Pine Tree (r), Travis (sss) 
 
 This is a sharply defined variety, differing from the typical form in 
 the bending of the spines so that they lie at right angles to the plane 
 of the cell. Lemmermann ’s figure 9 shows this very well but for some 
 reason the cell in his figure 8 has no spines and so is not at all charac- 
 teristic. 
 
 Tetraedron pentaedricum W. & G. S. West. PI. 25, Figs. 13-17. 
 Trans. Linn. Soc. 2nd iSer. Bot. 5: 84, pi. 5, figs. 15-16. 1895. 
 
 Cells small, five-cornered, with four corners in one plane and the fifth 
 lying at an angle of 30-90 degrees. Corners subacute, each with a 
 single, short, curved spine. Chloroplast single, parietal, with one pyre- 
 noid. (Facultative Planktont). 
 
 Diam. cells (without spines) 5.5-14 fi, (with spines) 9-20 fx. 
 
 Soft (rr). 
 
 T. pentaedricum has not been observed since it was described from 
 Madagascar by the Wests. Chodat considers it a synonym of T. cau- 
 datum (Corda) Hansg. erroneously citing it as Tetrapedia pentaedri- 
 cum (Mater, pour la fl. crypt. Suisse 1^: 219. 1902). Isolation of this 
 
WISCONSIN PHYTOPLANKTON 
 
 121 
 
 alga in pure culture with the retention of its distinguishing character 
 shows that the Wests are correct in considering it a distinct species. 
 It resembles T. caudatum in the size, number of corners, character of 
 spines at the corners, and the concave sides ; but differs in having four 
 corners in approximately the same plane and the fifth at an angle with 
 the plane of the other four. There is considerable variation in the 
 angle at which this fifth corner lies but it is never in the same plane as 
 the other corners. The Wests (1. c. fig. 17) also describe a variety 
 minima which, as the name implies, is smaller. I find that the variations 
 in size of cells of the typical form in a pure culture include the dimen- 
 sions set for the variety minima so that this variety cannot be recognized. 
 
 Tetraedron hastatum (Reinsch) Hansgirg. PI. 25, Fig. 18. 
 Hedwigia 27: 132. 1888. 
 
 Polyedrium tetraedricum var. hastatum Reinsch, Die Algenfl. d. mitt. Th. t. 
 Franken 77, pi. 5, iigs. 3a-3b. 1867. 
 
 Cells medium sized, pyramidate, with the angles produced into long 
 tapering and somewhat concave processes. Processes unbranched but 
 having 2 or 3 short spines at the tip. (Tychoplanktont). 
 
 Diam. cells (with processes) 28-36 /a; diam. base of process 8 /jl. 
 
 Horse (rrr). 
 
 The general shape of the cell is similar to that of T. limneticum but 
 there is no branching of the processes. 
 
 var. PALATiNUM (Schmidle) Lemmermann. PI. 25, Figs. 19-21. 
 
 Ber. d. D. hot. Ges. 20: (247). 1902. 
 
 Polyedrium hastatum var. palatinum Schmidle, Ber. d. D, hot. Ges. 18: 148, 
 149, pi. 6, figs. 4-5. 1900. 
 
 Cells pyramidal, with convex sides, angles produced into fairly deli- 
 cate non-tapering processes about as long as the diameter of the cells. 
 Processes unbranched but with three short spines at the apex. (Ty- 
 choplanktont) . 
 
 Diam. cells (without processes) 4^14 y.; length processes about 10 fi. 
 
 Horse (rr). 
 
 The processes at the angles of the cell do not seem as much a part 
 of the cell as in the typical form. Although both the typical form 
 and the variety palatinum were found at the same station the two seem 
 distinct and without transition forms. 
 
122 
 
 WISCONSIN PHYTOPLANKTON 
 
 Tetraedron constrictum nom. nov. PI. 25, Figs. 22-24. 
 
 Tetraedron arthrodesmiforme var. lohulatum Woloszynska, Hedwigla 55: 
 203, pi. 6, fig. 11. 1914. 
 
 Cells medium sized, tetragonal, flattened, two sides straight and two 
 opposite sides concave. Angles produced into narrow slightly taper- 
 ing processes which give the cell a decided H-shape. Ends of proc- 
 esses generally dichotomously branched the branchlets ending in two 
 short spines. (Euplanktont). 
 
 Diam. cells (without processes) 5-8 /a; length 18-25 fi; thickness 8 fx. 
 licngth of processes 10-15 (i. 
 
 Bone (rr). 
 
 Woloszynska has found these peculiar H-shaped cells in the plankton 
 of Lake Victoria Nyanza, Africa and placed them among other varieties 
 of T. arthrodesmiforme described at the same time. The variety lohu- 
 latum is, however, sufficiently different from the other varieties to war- 
 rant raising it to speciflc rank. Bone lake is the only station where it 
 has been found but several individuals were seen in the catch from 
 this lake. 
 
 Tetraedron gracile (Reinsch) Hansgirg. PI. 26, Figs. 1-5. 
 Hedwigia 28: 19. 1889. 
 
 Polyedrium gracile Reinsch, Notarisia 3: 502, pi. 7, figs, la-lc. 1888. 
 
 Cells medium size, conspicuously flattened, rectangular, with flattened 
 sides. Angles of cells produced into narrow processes that generally 
 branch twice and end in minute spines. The primary branchings of 
 the processes are at an angle of 90 degrees with one another and always 
 parallel with a side of the cell. Each cell containing several, parietal 
 disciform to laminate chloroplasts without pyrenoids. (Euplanktont). 
 
 Diam. cells (without processes) 15-30 /a; (with processes) 35-80 fx) 
 thickness of cells 6-12 /a. 
 
 Bear (1) (rr). Bear Trap (rrr), Blake (rr). Chain (rr), Elizabeth (rrr), 
 Hillman (sss). Loon (rrr). Pine (2) (rr), Poor Farm (rr). Round (rr), Travis 
 (r), Wapagossett (rr). 
 
 Tetraedron lobulatum (Nageli) Hansgirg. PI. 26, Figs. 6-7. 
 Hedwigia 27: 132. 1888. 
 
 Polyedrium lohulatum Nageli, Gatt. einz. Algen 84, pi. 4, figs. B4a-B4b. 1849. 
 
 Cells medium sized, tetragonal, flattened, or pyramidal. Processes 
 of angles with one or two short dichotomous branchings that generally 
 do not end in spines. Sides of cells distinctly concave. Cells contain- 
 
WISCONSIN PHYTOPLANKTON 
 
 123 
 
 ing several parietal disciform chloroplasts without pyrenoids. (Tycho- 
 planktont) . 
 
 Diam. cells (with processes) 30-40 fi. 
 
 Birch Island (rrr), Long (3) (rrr), Sand (2) (rr). 
 
 The specimens from Sand lake were of particular interest since three 
 showed the production of autospores (fig. 6). The chloroplast of old 
 cells are frequently indistinct but they can be seen quite readily in 
 young cells. 
 
 var. POLYFURCATUM G. M. Smith. PI. 26, Fig. 8. 
 
 Bull. Torr. Bot. Cl. 43: 480, pi. 26, figs. 21-22. 1*916. 
 
 Cells tetragonal, flattened or pyramidal; with concave, straight, or 
 slightly convex sides. Processes at angles somewhat tapering, 3-5 times 
 dichotomously branching, the ultimate branchlets with 2-3 minute 
 spines. (Facultative Planktont). 
 
 Diam. cells (without processes) 15-25 fi, (with processes) 35-70 /x. 
 
 Beaverdam (r), Blake (rr). Bone (rr), Clare (rr), Fish (rr). Loon (rr), 
 Muskallonge (rrr). Palmer (r), Pardee (r), Pine Tree (rr), Rice (1) (rr). 
 Shell (rr). Wild Goose (rrr). 
 
 Differing from the typical form in the greater branching of the 
 processes and from T. enorme (Ralfs) Hansg. in the much longer proc- 
 esses. 
 
 Tetraedron limneticum Borge. PI. 27, Figs. 1-3. 
 
 Bot. Not. 1900: 5, pi. 1, fig. 2. 1900; W. & G. S. West, Trans. Roy. Soc. Edin- 
 burgh 41: 507, pi. 6, figs. 10-11. 1905. 
 
 Cells of medium size, tetragonal, pyramidal, the four angles being 
 produced into one or two dichotomous branchings. Terminal branch- 
 lets with 2-3 short spines. (Euplanktont). 
 
 Diam. cells (with processes) 45-85 p.; diam. base of processes 8-12 p. 
 
 Chain (rr), Chetek (r). Clear (r). Crawling Stone (rrr). Deer (rr). Diamond 
 (rrr). Island (rr). Kitten (rr), Little Butternut (rr). Little Crooked (rrr), 
 Mud (2) (r), Nancy (rr). Palmer (rr). Pine Tree (rr). Poplar (rr). Spirit 
 (rrr). Squirrel (rr). Wildcat (rr). Wild Goose (rrr). Wolf (rr). 
 
 Tetraedron planctonicum G. M. Smith. PI. 27, Figs. 4-5. 
 
 Bull. Torr. Bot. Cl. 43 : 479, pi. 26, figs. 19-20. 1916. 
 
 Cells medium-sized, four to five sided, sides concave to convex. Angles 
 of cells produced into narrow, once to twice dichotomously branched 
 processes. Ultimate branchlets with 2-3 short spines. Processes broad 
 in front view, narrow in side or vertical view. (Euplanktont). 
 
124 
 
 WISCONSIN PHYTOPLANKTON 
 
 Diam. cells (without processes) 18-30 /x; (with processes) 45-60 /x. 
 
 Cranberry (rr), Cochrane (rr), Devils (2) (sss), Granite (rr), Horseshoe 
 (1) (rr), Lindy (rrr), Lost (rr), No Mans (rr), Prairie (rr). Rock (rr). Ver- 
 milion (r). 
 
 The chief difference between this species and T. Umneticum is the 
 greater size of the cells in proportion to the length of the processes. 
 
 Tetraedron enorme (Ralfs) Hansgirg. PI. 27, Fig. 6. 
 Hedwigia 27: 132. 1888; G. S. West, Brit. Freshw. Algae 231, fig. IOId. 1904. 
 
 Cells irregularly tetrahedric, angles produced into short processes 
 and sides emarginate. Processes generally bilobed and ending in short 
 spines. ( Tychoplanktont ) . 
 
 Diam. cells 25-45 fx. 
 
 Carson (rr), Cochrane (rr), Devils (2) (r). Horse (rrr). Horseshoe (2) 
 (rrr). Lake of the Woods (rrr), Okauchee (rrr). Pine (2) (rr). 
 
 POLYEDRIOPSIS Schmidle 1899. 
 
 Cells solitary, generally tetragonal, flattened; rarely pyramidal cr 
 with sides cruciate. Corners truncate and with 3-10 long, hyaline, 
 slightly tapering setae. Chloroplast parietal or entirely Ailing the 
 cell, pyrenoid single. 
 
 Reproduction by the formation of 2-4-8 autospores through the divi- 
 sion of the cell contents. 
 
 PoLYEDRiOPSis SPiNULOSA Schmidle. PI. 27, Figs. 7-8, 
 
 Allg. Bot. Zeitschr. 5: 17. 1899. 
 
 Tetraedron spinulosnm Schmidle, ibid. 2: 193, fig. 2. 1896. 
 
 Characters the same as those of the genus. (Euplanktont). 
 Greatest diameter of cells 12-25 fi ; length of setae about 40 fi. 
 
 Horse (rr). Prairie (rrr). 
 
 The general tendency among phycologists is to follow Wille’s prac- 
 tice and place the alga in a special sub-genus of Tetraedron. The 
 setae on the cell angles are of the same type as those found on Lager- 
 heimia and Micractinium so that Polyedriopsis forms, in my opinion, 
 a genus parallel with Tetraedron just as Lagerheimia does with Oocystis. 
 
WISCONSIN PHYTOPLANKTON 
 
 125 
 
 Sub-family MICEACTINIEAE. 
 
 Cells solitary or in colonies; spherical or ovoid; with long hyaline 
 setae or spines completely covering or restricted to certain parts of the 
 cell wall. Chloroplast single and cup-shaped ; or laminate to disciform 
 and from one to several in each cell. Chloroplasts generally with pyrv3- 
 noids. 
 
 KEY TO THE GENERA. 
 
 Cells spherical. 
 
 Cells organized into definite colonies Micractinium (p.p.) 
 
 Cells solitary. 
 
 Wall covered with fine hair-like setae. 
 
 Setae thickened in lower third Acanthospheaeba 
 
 Setae not thickened in lower third Golenkinia 
 
 Wall covered with delicately tapering spines Echinosphaerella 
 
 Cells ovoid. 
 
 Cells organized into definite colonies Micractinium: (p.p.) 
 
 Cells solitary. 
 
 Setae somewhat tapering Lagerheimia 
 
 Setae not tapering Franceia 
 
 MICRACTINIUM Fresenius 1858. 
 
 Cells spherical or ovoid, in colonies of 4-32 or more, generally quad- 
 rately arranged in one plane but sometimes tetrahedrically disposed. 
 Cell wall delicate, with 1-7 long hyaline setae that are not thickened 
 at the base lying on the free surface of the cells. Chloroplast single, 
 parietal, cup-shaped ; with one pyrenoid. 
 
 Reproduction by the division of contents of any cell to form a 4- or 
 8-celled autocolony, the young colony being liberated by a rupture of 
 the mother cell wall into four parts. Young coenobia frequently re- 
 maining attached to the parent coenobe for some time. 
 
 KEY TO THE SPECIES. 
 
 Cells spherical M. PusiixuM 
 
 Cells ovoid M. Quadrispenum 
 
 Micractinium pusillum Fresenius. PL 28, Figs. IS. 
 
 Abh. Senckenb. Naturf. Ges. 2: 236, pi. 11, figs. 46-49. 1858; G. M. Smith, Bull. 
 Torr. Bot. Cl. 43: 477, pi. 25, fig. 18. 1916. 
 
 Richteriella hotryoides (Schmidle) Lemmermann, Hedwigia 37: 307, pi. 10, 
 figs. 1-6. 1898. 
 
 Richteriella hotryoides forma fenestrata Chodat, Mater, pour la flore crypt. 
 Suisse V: 194, fig. 110. 1902. 
 
126 
 
 WISCONSIN PHYTOPLANKTON 
 
 Richteriella lotryoides forma tetraedrica Lemmermann, Arch. f. Hydrobiol. 
 u. Planktonkde. 5: 307. 1910. 
 
 Colonies of 4-8-16 or more cells in groups of four and disposed in a 
 quadrate or pyramidate manner with the groups of four in turn pyra- 
 midately or quadrately arranged. Cells spherical, with 1-5 long, hya- 
 line, delicately tapering setae on the face not adjacent to other cells. 
 Chloroplast single, parietal, cup-shaped; with one pyrenoid. (Eu- 
 planktont). 
 
 Diam. cells (without setae) 3-7 /x; length of setae 20-35 /x. 
 
 Blake (rrr), Bone (sss), Chain (sss), Chetek (rr), East (rr), Green (1) 
 (rr), Hooker (rr), Horse (rr), Horseshoe (2) (rrr). Island (rrr), Little Bass 
 (2) (r). Little Crooked (rrr). Loveless (r), Mendota (rr), Monona (cc). North 
 Turtle (rr), Pokegama (3) (rr). Poor Farm (rr). Pope (rr), Prairie (rr), 
 Round (1) (rr). Tenderfoot (rrr). Tied Canoe (rr). Wolf (rrr). 
 
 Flat sixteen-celled colonies with a central open space are the most 
 common. Such colonies have been given the form name fenestrata but 
 both it and the form tetraedrica are unworthy of recognition. On rare 
 occasions large colonies are found; colonies containing over 750 cells 
 having been collected from the plankton of Lake Monona. 
 
 var. ELEGANS G. M. Smith. PI. 29, Pig. 1. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19h 631, pi. 12, fig. 4. 1918. 
 
 Cells with 5-7 setae on the exposed face. Dimensions as in the 
 typical form. (Euplanktont). 
 
 Rice (1) (rr). 
 
 This seems to be a distinct variety since the cells of colonies from 
 this lake all bore the large number of setae. 
 
 Micractinium quadrisetum (Lemmermann) G. M. Smith. PI. 28, 
 
 Fig. 4 . 
 
 Bull. Torr. Bot. Cl. 43: 479, pi. 25, fig. 17. 1916. 
 
 Cells ovoid, with 1-4 long, delicately tapering setae on the exposed 
 faces. Chloroplast single, parietal, cup-shaped; with one pyrenoid. 
 (Euplanktont). 
 
 Diam. cells (without setae) 4-7 fi, length 8-10 /x; length of setae 
 23-40 fx. 
 
 Bear Trap (rrr). Camp (rr). Cranberry (rrr). Eagle (rrr). 
 
 The cells of this species are somewhat larger than those of M. pusil- 
 lum and are distinctly ovoid. The character upon which the specific 
 
WISCONSIN PHYTOPLANKTON 
 
 127 
 
 name is based is quite misleading since the number of setae may vary 
 from one to four. Colonies containing more than sixteen cells have 
 not been observed and the cell arrangement has been quadrate in every 
 case. 
 
 GOLENKINIA Chodat 1894. 
 
 Cells spherical, normally solitary; occasionally forming temporary 
 colonies. Cell wall thin, sometimes enclosed in a thin gelatinous en- 
 velope. Surface of cell covered with hyaline setae that are slightly 
 tapering but not conspicuously thickened in the lower third. Chloro- 
 plast single, parietal and cup-shaped or entirely filling the cell; pyre- 
 noid single. 
 
 Keproduction by the formation of autospores. Zoospores have been 
 reported but their formation is doubtful. 
 
 KEY TO THE SPECIES. 
 
 Setae 25-45 long G. Radiata 
 
 Setae 12-18 long G. Patjcispina 
 
 Golenkinia radiata Chodat. PI. 29, Figs. 2-3. 
 
 Jour, de Bot. 8: 305, 2 )Z. 3, figs. 1-24. 1894. 
 
 Cells spherical, solitary, sometimes in temporary colonies of four 
 cells. Entire cell wall covered with long, delicate, hyaline setae. Chlor- 
 oplast single, cup-shaped, parietal ; with one pyrenoid. (Euplanktont) . 
 
 Diam. cells (without setae) 7-15 /x; length setae 25-45 /x. 
 
 Green (2) (rrr), White Ash (rr). 
 
 This and the following Golenkinia species have been made a sub- 
 genus of Micractinium by Wille and that terminology followed in the 
 second list but the colonial and solitary habit seem to me sufficiently 
 diverse to v/arrant generic distinction. 
 
 Golenkinia paucispina W. & G. S. West. PI. 29, Figs. 4-5. 
 
 Trans. Roy. Irish Acad. 32, Sec. B: 68, pi. 1, fig. 18. 1902. 
 
 Cells solitary, spherical, with few to fairly numerous, short, delicately 
 tapering, hyaline or dark setae. Chloroplast single, completely filling 
 the cell, with one pyrenoid. (Euplanktont). 
 
 Diam. cells (without setae) 15-18 /x; length setae 12-18 /x. 
 
 Prairie (rr). 
 
 The setae of the cells in Prairie lake were more numerous than the 
 Wests found them in individuals from the plankton of Lough Neagh, 
 
128 
 
 WISCONSIN PHYTOPLANKTON 
 
 Ireland. They were also dark colored and are more conspicuous than 
 in other members of the Micractineae. 
 
 ACANTHOSPHAERA Lemmermann 1899. 
 
 Cells spherical, solitary, with a single cup-shaped chloroplast con-' 
 taining one pyrenoid. Cell wall thin, without a gelatinous sheath; 
 covered with many long hyaline setae that are thicker in the lower 
 third and then abruptly diminish to a very fine hair. 
 
 Method of reproduction unknown. 
 
 Acanthosphaera Zachariasi Lemmermann. PI. 29, Figs. 6-8. 
 Forschungsbr. a. d. Biol. Stat. zu Plon 7: 118, pi. 1, figs. 10-11. 1899. 
 
 Characters as those of the genus. (Euplanktont). 
 
 Diam. cells (without setae) 9-14.5 /x; length setae 30-35 /x. 
 
 Horse (rr). 
 
 The chief distinction between this genus and Golenkinia is the thick- 
 ening of the lower part of the setae. 
 
 Echinosphaerella gen. nov. 
 
 Cells spherical, solitary. Cell wall thin, completely covered with 
 heavy, long, hyaline, delicately tapering and slightly concave, homo- 
 geneous spines. Chloroplast single, parietal, cup-shaped; with one 
 pyrenoid. 
 
 Reproduction unknown. 
 
 Echinosphaerella limnetica sp. nov. PI. 29, Figs. 9-11. 
 
 Characters as described above. (Euplanktont). 
 
 Diam. cells (without spines) 9-12 fi. Spines 2.5-3 /x broad at base, 
 20-25 fjL long. 
 
 Horse (rr). 
 
 The alga at once suggests a desmid zygospore, especially those of 
 certain Staurastrum species. In all desmid zygospores the chloroplast 
 is not definite and since the alga collected from Horse Lake has a 
 single, well defined, cup-shaped chloroplast with one pyrenoid the pre- 
 sumption is that it is a vegetative cell and not a zygospore. The 
 nearest genus is Echinosphaeridium Lemmermann where the setae 
 covering the wall have a broad tapering gelatinous sheath at the base. 
 In Echinosphaerella there is not a central hair-like seta with a gelati- 
 nous covering, but a homogeneous spine of considerable thickness at the 
 
WISCONSIN PHYTOPLANKTON 
 
 129 
 
 base. Although the genus is provisionally placed in the Micractinieae 
 its spines are quite different from those of other genera of the sub- 
 family. 
 
 LAGERHEIMIA Chodat 1895. 
 
 Cells solitary; ovoid, ellipsoid, or citriform. Cell wall firm, without 
 a gelatinous sheath; with long tapering setae that lie a short distance 
 back from the poles or cover the entire wall. Chloroplasts 1-4, pari- 
 etal, laminate; with or without pyrenoids. 
 
 Reproduction by autospores that are generally liberated at once but 
 which may remain inside the old mother wall a short time. 
 
 KEY TO THE SPECIES. _ 
 
 Setae covering entire cell wall L. Droescheri 
 
 Setae confined to poles of the cell. 
 
 Cells lemon-shaped L. Citriformis 
 
 Cells ovoid. 
 
 Length of setae more than double that of cell L. Longiseta 
 
 Length of setae less than double that of cell. 
 
 2- 4 setae at each pole L. Subsalsa 
 
 3- 8 (generally 6) setae at each pole L. Ciliata 
 
 Lagerheimia ciliata (Lagerheim) Chodat. PI. 31, Figs. 1-2. 
 Nuova Notarisia 10: 90. 1895. 
 
 Oocystis ciliata Lagerheim, ofvsers Kgl. Vet.-Ak. Porh. 39, No. 2: 76, pi. 3, 
 figs. 33-37. 1882. 
 
 Chodatella ciliata (Lag.) Lemmermann, Hedwigia 37: 310. 1898. 
 
 Cells oblong-ovoid, with 3-7, hyaline, delicately tapering setae at 
 each pole. Chloroplasts 1-4, parietal, laminate; each with a single 
 pyrenoid. ( Euplanktont) . 
 
 Breadth of cells (without setae) 6-18 ja; length (without setae) 10- 
 • 21 fi. Setae 15-20 fx long. 
 
 Kegonsa (rr), Mendota (sss). 
 
 The setae of this species are not in definite whorls but distributed over 
 the entire polar region. 
 
 var. minor (G. M. Smith) comb. nov. PI. 31, Fig. 3. 
 
 Chodatella ciliata var. minor G. M. Smith. Bull. Torr. Bot. Cl. 43: 477, 
 pi. 25, fig. 16. 1916. 
 
 Cells ovoid, with 6-8 setae at each pole. (Euplanktont). 
 
 Diam. cells (without setae) 6-7.5 /x; length (without setae) 8-10 fx. 
 Setae about 20 /t long. 
 
 Muskallonge (rr). 
 
 9 
 
130 
 
 WISCONSIN PHYTOPLANKTON 
 
 Lagerheimia subsalsa Lemmermann. PI. 30, Figs. 3-4. 
 
 Forschungsbr. a. d. Biol. Stat. zu Plon 6: 193, pi. 5, figs. 2-6. 1898. 
 
 Chodatella subsalsa Lommermann, Hedwigia 37: 310. 1898. 
 
 Cells ovoid, with 2-4 delicate setae at each pole. Chloroplast single, 
 laminate, parietal; with one pyrenoid. (Euplanktont). 
 
 Diam. cells (without setae) 2.5-8 /x; length (without setae) 5-12 fi. 
 Setae 7.5-26 /x long. 
 
 Deer (rrr), Geneva (rr). 
 
 Lagerheimia longiseta (Lemmermann) Printz. PI. 30, Figs. 8-9. 
 
 Skr. Vidensk. i Kristiania, Mat.-Naturv. Kl. 1913% No. 6: 60. 1914. 
 
 Chodatella longiseta Lemmermann, Hedwigia 37: 310, pi. 10, figs. 11-18. 
 18’98. 
 
 Cells ellipsoid, with a whorl of 4-10 long, hyaline, delicately tapering 
 setae a short distance from each pole. Chloroplast single ( ?), parietal; 
 without a pyrenoid (?). (Euplanktont). 
 
 Breadth of cells (without setae) 5-8 fi; length (without setae) 9-13 ju. 
 Setae 40-55 /x long. 
 
 White Sand (sss). 
 
 The exceedingly long setae at once distinguish the species from all 
 others. The arrangement of the setae in a whorl is best seen in an end 
 view of a cell. 
 
 var. major var. nov. PI. 30, Figs. 10-12. 
 
 Cells ovoid, with somewhat pointed ends. With a whorl of 4-7 setae 
 a short distance from each pole. Cells containing 1-2 laminate pari- 
 etal chloroplasts each with a single pyrenoid. (Euplanktont). 
 
 Breadth of cells (without setae) 12-15 /x; length (without setae) 
 15-22 fx. Setae 45-60 fi long. 
 
 Blake (rr). Little Bass (2) (rrr). 
 
 The variety is distinguished from the typical form by the more 
 pointed and larger cells. 
 
 Lagerheimia citriformis (Snow) comb. nov. PI. 30, Pigs. 1-2. 
 
 Chodatella citriformis Snow, Bull. U. S. Pish Comm. 22: 389, pi. 2, figs. 
 8^-8’. 1903. 
 
 Cells ovoid to ellipsoid, with a small obtuse projection at each pole. 
 Poles with a whorl of 4-8 long, hyaline, delicately tapering setae at the 
 
WISCONSIN PHYTOPLANKTON 
 
 131 
 
 base of the polar projections. Chloroplast single, parietal; with one 
 pyrenoid. ( Euplanktont) . 
 
 Breadth cells (without setae) 8-20 fi; length (without setae) 13-23 fj.. 
 Setae 25-35 fi long. 
 
 Horse (rrr), Kegonsa (rrr). 
 
 This is the only species with polar projections that resemble the 
 polar nodules of Oocystis. 
 
 Lagerheimia Droescheri (Lemmermann) Printz. PI. 30, Figs. 5-7. 
 
 Skr. Vidensk. i Kristiania Mat.-Naturv. Kl. 1913% No. 6: 60. 1914. 
 
 Chodatella Droescheri Lemmermann, Ber. d. D. Bot Ges. 18: 98, ph 3, fig. 12. 
 1900. 
 
 Cells ovoid to ellipsoid; with numerous hyaline delicately tapering 
 setae covering the entire wall. Cells with 2-A parietal, laminate 
 chloroplasts ; each with a single pyrenoid. (Euplanktont). 
 
 Breadth of cells (without setae) 5-12 fi; length (without setae) 9-16 
 fi. Setae 15-22 long. 
 
 Horse (rrr), Travis (r). Upper Nashotah (rr). 
 
 FEANCEIA Lemmermann 1898. 
 
 Cells ovoid, solitary or in colonies of 2-4; free-floating. Cells en- 
 closed in a delicate gelatinous sheath (?). Entire cell wall covered 
 with delicate hyaline setae that do not taper. Chloroplasts 1-3, pari- 
 etal, laminate, with or without pyrenoids. 
 
 Eeproduction by autospores. 
 
 Franceia ovalis (France) Lemmermann. PI. 31, Fig. 4. 
 Hedwigia 37: 308. 1898. 
 
 Phythelios ovalis Franc6, Notarisia 1894: 2, figs. 1-5. 1894. 
 
 Cells ovoid to elliptic; with two chloroplasts. (Euplanktont). 
 Breadth of cells (without setae) 7-10 /x; length (without setae) 13- 
 17 fx. Setae 15-23 fx long. 
 
 Pine Tree (rr). 
 
 The minimal dimensions given above are somewhat smaller than those 
 given by France but I feel that the Wisconsin organism should not be 
 considered a distinct variety until the variation in size of the typical 
 form has been determined -more fully. 
 
 The recognition of the genus Franceia is open to question since the 
 characters upon which Lemmermann bases the genus (number of 
 
132 
 
 WISCONSIN PHYTOPLANKTON 
 
 chloroplasts, presence of a vacuole, and cell division in one plane) are 
 ones which might be found in any Lagerheimia species. The setae, 
 however, are very delicate and do not taper so that the genus is pro- 
 visionally considered distinct from Lagerheimia. 
 
 Sub-family SELENA8TREAE. 
 
 Cells elongate, straight or curved; with finely pointed ends or with 
 ends rounded. Solitary or associated in colonies containing an indefi- 
 nite number of cells. Colonies with or without a gelatinous envelope. 
 Cells generally with one parietal chloroplast that is with or without 
 pyrenoids. 
 
 KEY TO THE GENERA. 
 
 Cells solitary. 
 
 Ends of cells produced into setae Schroedebia 
 
 Ends of cells not produced into setae. 
 
 Chloroplast with an axial row of pyrenoids Closteriopsis 
 
 Chloroplast never with more than a single pyrenoid . Ankistrodesmus (p. p.) 
 Cells in colonies. 
 
 Colonies not enclosed in a gelatinous sheath. 
 
 Cells straight, in loose fasiculate bundles or spirally 
 
 twisted around one another Ankistrodesmus (p. p.) 
 
 Cells curved, with convex faces towards one another Selenastbum 
 
 Colonies enclosed in a gelatinous sheath. 
 
 Cells curved Kirchneriella 
 
 Cells straight. 
 
 Colonies with cells in groups of two Elaktothrix 
 
 Colonies with cells in groups of 2-4-8 Quadrigula 
 
 SELENASTRUM Reinseh 1867. 
 
 Cells broadly to narrowly acicular, semilunar; joined by their con- 
 vex faces into colonies of 4^8-16 or more cells without a gelatinous en- 
 velope. Chloroplast single, parietal, laminate, on convex side of young 
 cells ; entirely filling older cells ; with one pyrenoid. 
 
 Reproduction by any cell forming 2-4-8 autospores which, when 
 liberated, have the arrangement of the cells in an adult colony. Auto- 
 spores remaining attached to parent colony for some time. 
 
 The statement is generally made that there are not more than six- 
 teen cells in a colony but I have found that in the plankton of Wiscon- 
 sin lakes the colonies sometimes contain over a hundred cells. 
 
WISCONSIN PHYTOPLANKTON 
 
 133 
 
 KEY TO THE SPECIES. 
 
 Cells arcuate, never sickle-shaped S. Westh 
 
 Cells arcuate to sickle-shaped. 
 
 Diameter of cells not exceeding 5 ai S. Geacile 
 
 Diameter of cells 5-8 S. Bibbaianum 
 
 Selenastrum gracile Keinsch. PI. 31, Fig. 5. 
 
 D. Algenfl. d. mitt. Th. v. Franken 65, pi, 4, figs. 3a-3b. 1867. 
 
 Cells lunate to sickle-shaped, quite narrow in proportion to their 
 length. Apices of cells acute. Chloroplast single, laminate, parietal, 
 on convex side of cell. Without a pyrenoid. (Facultative Planktont). 
 
 Diam. cells 3-5 p , ; length 15-30 fx. Distance between apices 8-20 p. 
 
 Bear (3) (rr), Chain (rr), Hillman (rrr). Horse (rr), Monona (r), 
 
 Pokegama (1) (rr), Prairie (rr). Upper Turtle (rrr), Whitefish (rr). 
 
 Differs from the next species in the more delicate cells. Possibly it 
 should be considered a variety of S. Bihmianum and not a distinct 
 species. 
 
 Selenastrum Bibraianum Reinsch. PI. 31, Figs. 6-7. 
 
 D. Algenfl. d. mitt. Th. v. Franken 64, pi. 4, figs. 2a-2b. 1867. 
 
 Cells in spherical to ovoid colonies of 4-8-16 or more with their con- 
 vex sides facing the center of the colony. Cells crescent-shaped lo 
 sickle-shaped, gradually tapering to a fairly sharp apex. Chloroplast 
 parietal, on convex side of and almost filling the cell ; pyrenoid single. 
 (Facultative Planktont). 
 
 Diam. cells 5-8 p ; length 20-38 p. Distance between apices 5-25 p. 
 
 Beaverdam (rr), Blake (rrr). Bone (rr), Deer (rrr), Little Bass (2) (rrr), 
 Loveless (rr), Mendota (rrr), Meta (r), Nancy (rr), Pewaukee (rr), Pine 
 Tree (rr). Poor Farm (rr). Rice (1) (rr). Spirit (rrr). Squirrel (rrr), Ten- 
 derfoot (rr), Travis (rr). White Ash (sss), Wolf (rr). 
 
 All descriptions of S. Bibraianum state that there are but four or 
 eight cells in the colony but I have found that in Wisconsin lakes there 
 may be over a hundred cells in the colony, the number of cells usually 
 ceasing to be a multiple of two after there are more than sixteen cells 
 in the colony. 
 
 Selenastrum Westii sp. nov. PI. 31, Figs. 8-10. 
 
 Selenastrum acuminatum G. S. West non Lagerheim, Jour, of Bot. 50 : 88, 
 figs. 5a-5&. 1912. 
 
 Colonies of 2-4-8 cells irregularly arranged with their convex sides 
 in apposition. Frequently dissociating into the individual cells when 
 
WISCONSIN PHYTOPLANKTON 
 
 .r.ature. Ceils innate to arcuate, never sickle-shaped; gradually taper- 
 ing to a shaj’p point. Chloroplast single, parietal on convex side of cell ; 
 without a pyrenoid. (Facultative Planktont). 
 
 Diam. cells 1. 5-2.5 /a. Distance between apices 15-18 /x. 
 
 Devils (1) (rr). 
 
 The cells of this species are quite like those of Scenedesmus acumi- 
 natus (Lagerheim) Chodat but their organization in the colony is quite 
 different. West has recently investigated an organism which he con- 
 siders identical with the Selenastrum acuminatum described by Lager- 
 heim. I have obtained West’s organism in pure culture and find that 
 the cell shape and colony organization is as he describes. The fortunate 
 rediscovery of Lagerheim ’s species from the plankton of Horse Lake 
 shows that in the organization of the colony it is a Scenedesmus and 
 that Chodat is entirely correct in removing the species from Selenast- 
 rum. The organism that West found is, on the other hand, a true 
 Selenastrum but is not the species which Lagerheim erroneously re- 
 ferred to Selenastrum. 
 
 ANKISTRODESMUS Corda 1838. 
 
 Cells acicular to fusiform ; straight, lunate, or sigmoid ; ends of cells 
 gradually tapering to a point; solitary or loosely aggregated without 
 order in temporary colonies that are not embedded in a gelatinous en- 
 velope. Chloroplast single, parietal, sometimes fragmented into small 
 pieces ; with or without a pyrenoid. 
 
 Reproduction by the formation of several autospores in any cell. 
 
 KEY TO THE SPECIES. 
 
 Cells twisted around one another A. Spiralis 
 
 Cells not twisted around one another A. Falcatus 
 
 Ankistrodesmus falcatus (Corda) Ralfs. PL 32, Pig. 1. 
 
 Brit. Desmidieae 180, pi. 34, figs. 3a-3b. 1848; G. S. West, Brit. Freshw. Algae 
 223, fig. 94a. 1904. 
 
 Cells acicular to narrowly fusiform, tapering very gradually to acute 
 apices, lunate or slightly arcuate. Length 12-24 times the diameter. 
 Seldom solitary, generally loosely associated in fasiculate bundles. 
 Chloroplast single, generally without pyrenoids. (Facultative Plank- 
 tont) . 
 
 Diam. cells 1.5-3. 5 fx; length 20-80 fx. 
 
 Fence (rrr). Half Moon (rrr), Horse (rr), Kawaguesaga (rrr), Lac du 
 Flambeau (rrr). Little Crooked (rr). Lost (rr), Oconomowoc (rrr), Pine 
 
WISCONSIN PHYTOPLANKTON 
 
 135 
 
 Tree (rr), Poor Farm (rr), Poplar (rr), Rock (1) (rr), Tenderfoot (rr), 
 White Ash (rr). 
 
 var. ACicuLARis (A. Braun) G. S. West. 
 
 Brit. Freshw. Algae 223, figs. 94b-94o. 1904. 
 
 Cells usually solitary, straight or slightly curved, apices acutely at- 
 tenuated. Chloroplast single, parietal, with or without a pyrenoid. 
 
 Cells 2.5-4 fi broad, 36-65 /x long. 
 
 Beaverdam (rr), Little Bass (1) (rrr), Mendota (rr). Rice (1) (rr), Wau- 
 besa (rrr). 
 
 var. TUMiDus (W. & G. S. West) G. S. West. PI. 32, Fig. 2. 
 
 Brit. Freshw. Algae 224, fig. 94d. 1904. 
 
 Cells solitary or in small aggregates, straight or curved, inflated at 
 the middle and with acute apices. Chloroplast single, parietal, with 
 or without pyrenoids. (Tychoplanktont). 
 
 Cells 4.5-6.S /a broad; 61-73 fi long. 
 
 Devils (1) (rrr), Mendota (rr). 
 
 var. MiRABiLis (W. & G. S. West) G. S. West. PI. 32, Figs. 3-5. 
 Brit. Freshw. Algae 224, fig. 94b. 1904. 
 
 Cells solitary, straight, lunate, or sigmoid; with acute apices; much 
 longer and narrower than the typical form. Chloroplast single, com- 
 monly fragmented by large vacuoles in the cytoplasm; without pyre- 
 noids. ( Euplanktont ) . 
 
 Cells 2-3.5 /A broad ; up to 150 /a long. 
 
 Bear (3) (rr), Bryer (rr), Chain (sss). Crab (rrr). Devils (1) (sss). 
 Devils (2) (rr). Dummy (rr), High (rr). Horseshoe (1) (rr). Reserve (rr). 
 Squirrel (rr), Travis (rrr), Whitefish (rr). 
 
 Ankistrodesmus spiralis (Turner) Lemmermann. PI. 32, Figs. 6-7. 
 
 Arch. f. Hydrobiol. u. Planktonkde. 4: 176. 1908. 
 
 Raphidium spirals Turner, Kgl. Sv. Vet.-Ak. Handl. 25, No. 5: 156, pi. 20, 
 fig. 26. 1892. 
 
 Ankistrodesmus falcatus var. spiralis (Turner) G. S. West, Brit. Freshw. 
 Algae 224. 1904. 
 
 Cells acicular, attenuated to acute apices ; in colonies of four or eight 
 and spirally twisted around one another in the middle of the cell but 
 with the extremities free. Chloroplast single, completely filling the 
 cell; without a pyrenoid ( ?). (Tychoplanktont). 
 
136 
 
 WISCONSIN PHYTOPLANKTON 
 
 Cells 1-2.5 ^ broad ; 20-40 long. 
 
 Grassy (rr), Silver (2) (rrr). 
 
 G. S. West places the alga as a variety of A. falcatus but the twist- 
 ing of the cell seems to be such a constant character that I have fol- 
 lowed Lemmermann’s practice in considering it a distinct species. 
 
 CLOSTERIOPSIS Lemmermann 1898. 
 
 Cells solitary, acicular, with ends produced into very acute apices, 
 without a gelatinous envelope. Chloroplast single, not interrupted 
 at the center of the cell, occupying the greater portion of the cell and 
 containing a single axial row of about a dozen pyrenoids. 
 
 The genus is very closely related to Ankistrodesmus, differing onh^ 
 in the greater length of the cells and the axial row of pyrenoids. It 
 also resembles certain Closteriwn species but the chloroplast of Closter- 
 ium is always interrupted at the center of the cell. Many feel that the 
 single species is not sufficiently differentiated to warrant its separation 
 from Ankistrodesmus, 
 
 CLOSTERIOPSIS LONGissiMA var. TROPICA W. & G. S. West. PI. 32, Fig. 8. 
 
 Trans. & Proc. Bot. Soc. Edinb. 23: 31, pi. 1, fig. 1. 1905. 
 
 RhapTiidium longissimum var. tropicum W. & G. S. West, Trans. Linn. Soc. 
 2nd. Ser. Bot. 6: 198. 1902. 
 
 Cells acicular, poles acute but not ending in a point of hair-like fine- 
 ness. (Facultative Planktont). 
 
 Cells 6-7.5 fx broad ; 225-370 /a long. 
 
 North Turtle (rr). 
 
 The dimensions of specimens that I have found agree with those given 
 for individuals from Ceylon but not with those from the Scotch plank- 
 ton. 
 
 SCHROEDERIA Lemmermann 1898. 
 
 Cells solitary, straight or curved, acicular; with one apex produced 
 into a fine seta tapering to a point, the other with a slightly broader 
 projection terminating in a small disc. Cells without a gelatinous en- 
 velope. Chloroplast single, parietal, laminate; with one pyrenoid. 
 
 Method of reproduction unknown. 
 
WISCONSIN PHYTOPLANKTON 
 
 137 
 
 ScHROEDERiA SETiGERA (Schroder) Lemmermann. PI. 32, Fig. 12. 
 
 Hedwi^ia 37: 311. 1898; G. M. Smith, Bull. Torr. Bot. Cl. 43: 473, pZ. 24, 
 fig. 8. 1916. 
 
 Length of cells 15-20 times breadth. (Enplanktont). 
 
 Cells 3-6 fi broad, 60-85 /a long (with spines). Length of spines 
 13-27 fi. 
 
 Chain (sss). Devils (1) (c). Long (2) (rr). Sand (1) (rr). 
 
 This peculiar alga has the general appearance of a Characium. Al- 
 though hundreds of individuals have been found, it has never been 
 found attached to other algae or to crustaceans so that it seems safe 
 to assume that it leads a free-floating and not an epiphytic existence. 
 The disc at one end of the setae described above has not been observed 
 by other investigators, possibly because the alga is very minute. 
 
 Reproductive stages have never been found so that the systematic 
 position of the genus is doubtful. Judging by the cell shape it is a 
 close relative of Ankistrodesmus, a genus to which it has been referred 
 by some. 
 
 ScHROEDERiA JuDAYi G. M. Smith. PI. 32, Figs. 9-11. 
 
 Bull. Torr. Bot. Cl. 43: 474, pZ. 24, Ms. 9-11. 1916. 
 
 Cells smaller than the foregoing. (Euplanktont). 
 
 Cells 2.5-6 II broad, 45-63 /t long (with spines). Length of spines 
 
 10-16 /X. 
 
 Amicoy (rr), Birch (rrr), Camp (rr), Delavan (rr), Kawaguesaga (rr), 
 Mendota (sss), Prairie (rr). Round (1) (rrr), St. Croix (rr). 
 
 QUADRIGULA Printz 1915. 
 
 Cells generally in groups of 2-4-8 with their long axes parallel to 
 the long axis of the colony and enclosed by a hyaline, homogeneous, 
 gelatinous sheath. Colonies ellipsoid, 2-5 times as long as broad. Cells 
 cylindrical to fusiform, A-1 times as long as broad, straight or slightly 
 curved. Chloroplast single, filling most of the cell; with or without 
 pyrenoids. 
 
 Reproduction by 2-4-8 autospores from each cell, the fasiculate group 
 of autospores frequently remaining within the envelope of the mother 
 colony for some time. 
 
138 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE SPECIES. 
 
 Ends of cells rounded Q. Pfitzeri 
 
 Ends of cells pointed. 
 
 Chloroplast notched at the center Q. Chooati 
 
 Chloroplast not notched at the center Q. Lacustbis 
 
 Quadrigfula Pfitzeri (Schroder) comb. nov. PL 33, Figs. 1-2. 
 
 Rhaphidium Pfitzeri Schroder, Verb. d. Nat.-Med. Ver. zu Heidelberg N. F. 
 7: 152, pi. 6, fig. 6. 1902. 
 
 Ankistrodesmus Pfitzeri (Schroder) G. S. West, Brit. Freshw. Algae 224, 
 figs. 94g-94h. 1904. 
 
 Cells about 7 times as long as broad, central portion cylindrical with 
 ends slightly tapering and rounded. Chloroplast generally filling the 
 entire cell, with or without a pyrenoid. (Euplanktont). 
 
 Breadth of cells 3-6 /x, length 22-45 (generally about 35) p.. 
 
 Bear (1) (rr), Beaver dam (rr), Blake (rr). Chain (rr). Clear (rr), 
 
 Cochrane (sss). Devils (1) (s), Fishtrap (rrr), Found (r), Fowler (rr), 
 Harris (rr), Hillman (ss), Jennie (rr). Lac Court Oreilles (rr), Lindy (rr). 
 Long (2) (rrr). Little Wood (rr). Mud (1) (rr), Mudhen (rr), Oconomowoc 
 (rr), Okauchee (rr). Palmer (sss), Pardee (rr). Pine Tree (r), Poplar (r). 
 Reserve (rr). Rice (1) (rr). Sand (1) (rr). Shell (rr), tSishebogema (rr), 
 Travis (rr). White Ash (r), Whitefish (rr). Wild Goose (rrr). 
 
 The chief characteristic of the genus is the arrangement of the cells 
 in groups of 2-4-8 with their long axes parallel to the long axis of the 
 colony, together with the gelatinous envelope that surrounds the colony. 
 Admitting the generic validity of Quadirigula, Ankistrodesmus Chodati 
 and A. lacustris are in a much more natural position when placed with 
 Quadrigvla species. 
 
 Quadrigula Chodati (Tanner-Fullman) comb. nov. PL 33, Fig. 3. 
 
 Raphidium Chodati Tanner-Fullman, Bull. Herb. Boiss. 2 Ser. 6: 156, figs. 
 1-11. 1906. 
 
 Ankistrodesmus Chodati (Tanner-Fullman) Brunnthaler, in Pascher, Siiss- 
 wasserfl. Deutschl., osterr. u. d. Schw. 5": 193, fig. 306. 1915. 
 
 Cells linear, arcuate, or lunate ; fusiform and tapering to sharp ends. 
 Longitudinally arranged in a gelatinous colony of 4-8-16 or more cells. 
 Cells with a single, parietal, laminate chloroplast that is notched at 
 the center and contains two pyrenoids. (Euplanktont). 
 
 Breadth of cells 3.5-7 p, length 30-80 p. Colonies up to 50x250 p. 
 
 Boulder (r). Little Bass (2) (rrr). Lac du Flambeau (rr). Sand (3) (ss). 
 
 Tanner-Fullman states that the cells are always lunate but those that 
 T have observed were always straight or slightly curved. The notching 
 of the chloroplast together with the two pyrenoids is such a distinct 
 
WISCONSIN PHYTOPLANKTON 
 
 139 
 
 feature that there can be no doubt of the identity of the Wisconsin alga 
 with his species. 
 
 Quadrigula lacustris (Chodat) comb. nov. PL 33, Figs. 4-6. 
 
 Raphidium Braunii var. lacustre Chodat, Bull. Herb. Boiss. 5: pi. 11, figs. 
 9-10. 1897; Mater, pour la fl. crypt. Suisse 1^: 200, fig. 117. 1902. 
 
 AnTcistrodesmus lacustre (Chodat) Ostenfeld, Hedwigia 46: 384. 1907. 
 
 Cells spindle-shaped, straight, with pointed ends. Cells rarely soli- 
 tary, generally irregularly distributed throughout, or in groups with 
 their long axes parallel to the long axis of the fusiform gelatinous 
 colonial envelope. Chloroplast single, parietal, laminate, at one side 
 of the cell or spirally twisted; generally with a single pyrenoid. (Eu- 
 planktont). 
 
 Cells 3-5 fjL broad, 20-25 /a long. 
 
 Blue Gill (rr). Browns (rr). Clear Crooked (cc). Green (2) (rr). Horseshoe 
 (1) (rr). Lynx (rr), Pokegama (2) (rr). Round (1) (rrr). 
 
 ELAKTOTHRIX Wille 1898. 
 
 Cells fusiform when mature, longitudinally arranged in pairs within 
 a fusiform homogeneous gelatinous matrix. Chloroplast single, laminate, 
 parietal, with one or two pyrenoids. Colonies epiphytic when young 
 and free-floating when mature; or free-floating throughout the life of 
 the plant. 
 
 Reproduction by a transverse division into two daughter cells which 
 remain unchanged for some time. Akinetes known. 
 
 Wille first placed the alga as a close relative of Actinastrum Hantz- 
 schi Lagerheim, but later thought it a relative of Coccomyxa Schmidle 
 (Wille, in Engler & Prantl, Nat. Pflanzenfam. V (Nachtr.) : 36, figs. 
 18^-18®. 1909) ; Pascher (Susswasserfl. Deutschl., Osterr. u. d. Schw. 
 
 5^: 220, figs. 25-26. 1915) places it among the algae of doubtful sys- 
 tematic position; while G. S. West (Algae 1: 202. 1916) thinks it 
 closely allied to Ankistrodesmus, a view which seems to me most logical 
 since Ankistrodesmus, Quadrigtda and Elaktothrix form a very natural 
 evolutionary series. 
 
 KEY TO THE SPECIES. 
 
 Both poles of cells acute E. Viridis 
 
 One pole of cell acute, the other generally rounded E. Gelatinosa 
 
 Elaktothrix gelatinosa Wille. PI. 34, Figs. 1-3. 
 
 Biol. Cent. 18: 302. 1898; in Engler & Prantl, Nat. Pflanzenfam. 1* (Nachtr.) : 
 36, figs. 18a-18b. 1909; W. & G. S. West, The Naturalist, 1909: 291, figs. 6a-6d. 
 1909. 
 
 Colonies free-floating, elongate fusiform to somewhat irregular ; with 
 
140 
 
 WISCONSIN PHYTOPLANKTON 
 
 the long axes of the cells parallel to the long axis of the colony. Cells 
 lying in pairs, spindle-shaped; generally with one pole rounded and 
 the other pointed. The rounded ends of a pair of cells in apposition. 
 Chloroplast single, parietal, laminate; with one pyrenoid. Colonies 
 rarely containing over fifty cells. (Euplanktont). 
 
 Cells 3-6 fx broad; 15-25 /a long. Colonies 10-30 fx broad; 70-160 
 fi long. 
 
 Crooked (rrr), Deer (rrr), Hillman (rr), Jag (rrr), Jennie (rr), Long (2) 
 (rrr), Long (3) (rr), Loon (rrr), Mudhen (rr). Pine (2) (rrr). Sand (2) 
 (rrr), Streitor (sss). 
 
 The dimensions of the cells and the general appearance of the colony 
 in individuals that I have found is more like the Wests’ description of 
 the alga as found in England. Wisconsin colonies rarely contain more 
 than sixteen cells. 
 
 Elaktothrix viridis (Snow) Printz. PI. 33, Fig. 7. 
 
 Skr. Vidensk. i Kristiania Mat.-Naturv. Kl, 1913^: No. 6: 31, pi. 1, figs. 9-12. 
 1914. 
 
 Fusola viridis Snow, Bull. U. S. Fish Comm. 22 : 389, pi. 2, figs. VP-VP. 1903. 
 
 Colony free-floating or epiphytic, fusiform or irregular; gelatinous 
 sheath of colony sharply defined, frequently showing remains of old ' 
 cell wall at apex. Cells broadly fusiform, straight or sigmoid, with 
 acute apices. Chloroplast single, completely filling the cell; with one 
 or two pyrenoids. (Tychoplanktont) . 
 
 Cells 6-15 II broad, 12-35 /x long. 
 
 Soft (rr). 
 
 KIRCHNEKIELLA Schmidle 1893. 
 
 Cells lunate to sickle-shaped with their apices almost touching; or 
 elongate, vermiform, arcuate, or spiral cylinders with rounded ends. 
 Associated without definite arrangement in colonies enclosed by a hya- 
 line, homogeneous, gelatinous envelope. Number of cells in young 
 colonies a multiple of two, in older colonies indefinite but rarely more 
 than seventy-five. Chloroplast single, parietal, on convex side of or 
 entirely filling the cell ; generally with a single pyrenoid. 
 
 Reproduction by the division of any cell to form four or eight auto- 
 spores that are liberated by a rupture of the old mother cell wall but 
 remain within the gelatinous envelope of the colony. 
 
■^WISCONSIN PHYTOPLANKTON 
 
 141 
 
 KEY TO THE SPECIES. 
 
 Cells lunate to sickle-shaped. 
 
 Ends of cells pointed K. Lunaris 
 
 Ends of cells rounded K. Obesa 
 
 Cells arcuate, spiral, or vermiform cylinders. 
 
 Breadth of cells 2 /a or less K. Contorta 
 
 Breadth of. cells over 2 /a K. Elongata 
 
 Kirchneriella lunaris (Kirchner) Mobius. PL 34, Fig. 4. 
 
 Abh. d. Senckenb. Naturf. Ges. 18: 331. 1894; Chodat, Mater, pour la fl. crypt. 
 
 Suisse 1®: 202, figs. 12r-12V. 1902. 
 
 Cells flattened, crescent-shaped, with apices some distance apart, 
 about twice as long as broad, ends tapering to a blunt point; irregu- 
 larly arranged in groups of four to eight within the gelatinous colonial 
 envelope. Chloroplast single, filling the entire cell with the exception 
 of a small part on the concave side; pyrenoid single. (Facultative 
 Planktont) . 
 
 Cells 3-8 fji broad, 6-15 /a long ; colonies up to 250 fx in diam. 
 
 Bear (3) (rr), Beaverdam (rr), Birch Island (rrr), Blake (rr). Chain (ss), 
 Chetek (rr), Cochrane (rr). Crab (rrr). Deer (rr), Devils (2) (rr). Duck 
 (rr), Dummy (sss), Elizabeth (rr). Green (2) (rr). High (rr), Hillman (r), 
 Horseshoe (1) (rr), Jag (rr), Lindy (rrr). Little Crooked (rrr). Little Doc- 
 tor (rr). Long (3) (rrr). Loveless (rr). Lower Turtle (rrr). Lynx (rrr), Men- 
 dota (rr), Meta (rr). Mud (2) (rr), Nancy (sss). North Twin (rrr). Paddock 
 (rr), Pardee (rr). Pine Tree (rr), Pokegama (1) (r), Pokegama (3) (sss), 
 Poplar (rr). Prairie (sss). Round (3) (rrr), St. Croix (r). Shell (r). Spirit 
 (rrr). Squirrel (rr). Upper Turtle (rrr). White Ash (rr). 
 
 The species differ from K.- obesa in the pointed ends of the cells. The 
 two are widely distributed plankton organisms but have never been 
 found in quantity in any lake of the state. 
 
 var. Dianae Bohlin. PL 34, Fig. 5. 
 
 Bih. Kgl. Sv.‘Vet.-Ak. Handl. 23, Afd. 3, No. 7: 20, pi. 1, figs. 28-30. 1897. 
 
 Cells curved until the apices are almost touching, apices more pointed 
 and frequently slightly twisted. (Facultative Planktont). 
 
 Cells 3-5 fl broad, 10-21 fi long. 
 
 Hillman (rr). Pine (2) (rr). White Ash (r). 
 
 The cell shape of this variety resembles that of Selenastrum but the 
 colony differs in being enclosed by a gelatinous envelope. The apices 
 are much sharper than in the typical form. 
 
142 
 
 WISCONSIN PHYTOPLANKTON 
 
 var. irregularis var. nov. PI. 35, Fig. 1. 
 
 Apices of cells twisted and frequently not pointing in the same direc- 
 tion. (Facultative Planktont). 
 
 Cells 4r-6 broad, 6-13 fi long. 
 
 Cochrane (rr), Pokegama (1) (r), Tenderfoot (rr). 
 
 Although the cell apices of K. lunaris var. dianae are sometimes not 
 in the same plane, they never exhibit the twisting found in this variety. 
 The twisting of the cells of this variety is similar to that of K. contorta 
 but they have the shape and pointed ends that characterize K, lunaris. 
 
 Kirchneriella obesa (W. West) Schmidle. PI. 35, Figs. 2-3. 
 
 Ber. d. Naturf. Ges. zu Freiburg i. B. 7: 16 (83). 1893; G. S. West, Brit. 
 
 Freshw. Algae 226, figs. 96a-96e. 1904. 
 
 Cells flattened with outer side markedly convex and inner sides 
 parallel, ends rounded and tapering slightly. Chloroplast single, fill- 
 ing the entire cell with the exception of a small portion on the con- 
 cave side; with one pyrenoid. (Facultative Planktont). 
 
 Cells 3-8 broad, 6-16 fx long. 
 
 Bear (2) (rr). Bear Trap (rr). Camp (rr), Catherine (rr), Center (r). 
 Chain (rr), Chetac (r). Crawling Stone (rrr). Devils (1) (rrr), Hillman (rr), 
 Kitten (rr). Lac Court Oreilles (ss), Lac du Flambeau (rr), Mendota (r). 
 Palmer (rrr). Pine Tree (rr), Pokegama (2) (rr). Poor Farm (rr). Reserve 
 (rr). Rice (1) (rr). Rock (rrr). Sand (4) (rr). South Turtle (rr). White- 
 fish (rrr). Wildcat (rr), Winnebago (rr). 
 
 The cells of this species might be described as thick discs incised a 
 third to a half the width of the cell did not other members of the genus 
 show that this effect is produced by a curving of the cell. 
 
 var. MAJOR (Bernard) G. M. Smith. PI. 35, Fig. 4. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 636, pi. 10, fig. 7. 1918. 
 
 Inner face between cell apices curved; apices not close together, 
 rounded and slightly tapering. (Facultative Planktont). 
 
 Cells 3-5 fi broad, 8-21 /x long. 
 
 Carson (rr). Lac Court Oreilles (r). Wolf (rr). 
 
 This variety has a large open space between the apices whereas in 
 the typical form this space is narrow and with parallel sides. The cells 
 are also much narrower in proportion to their length. Brunnthaler 
 (in Pascher, Siisswasserfl. Deutschl. Osterr. u. d. Schw. 5^: 180. 1915) 
 
 has placed the alga as a form of K. lunaris var. dianae but the cell apices 
 are too rounded to consider it a variety of K. luTiaris. 
 
WISCONSIN PHYTOPLANKTON 
 
 143 
 
 Yar. APERTA (Teiling) Briinntlialer. PI. 35, Figs. 5-6. 
 
 in Pascher, Siisswasserfl. Deutschl. osterr. u. d. Schw. 5^: 182, iig, 268. 1915. 
 
 Kirchneriella aperta Teiling, Sv. Bot. Tids. 6; 276, fig. 9. 1912. 
 
 Cells with blunt, rounded apices, concave side between apices broadly 
 V-sbaped. (Facultative Planktont). 
 
 Diam. cells 6-12 fx. 
 
 Diamond (rr), Palmer (ss). 
 
 Kirchneriella contorta (Schmidle) Bohlin. PI. 35, Fig. 7. 
 
 Bih. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 20. 1897. 
 
 Kirchneriella obesa var. contorta Schmidle, Flora 78: 44, pi. 7, fig. 2. 1894. 
 
 Cells cylindrical, arcuate or in spirals that never make more than 
 iy 2 turns; ends rounded, not tapering. Cells generally lying some 
 distance from one another within the homogeneous colonial envelope. 
 Chloroplast single, filling the entire cell, without a pyrenoid. Cells 
 sometimes spirally arranged in the colony; rarely more than sixteen 
 cells in a colony. (Facultative Planktont). 
 
 Cells 0.7-2.0 fi broad, 8-14 /x long ; colonies up to 60 ^ in diam. 
 
 Chain (rrr), Clear (rr), Cochrane (rr), Fowler (rrr), Mendota (rrr), Par- 
 dee (rr), Pine Tree (rrr). Poor Farm (rrr). 
 
 A species which at first glance does not appear related to K. lunaris 
 and K. obesa, but which at times shows a certain resemblance to 
 K. obesa var. major. It and the following species are rare algae in 
 Wisconsin. They are closely related, the chief difference being the 
 smaller size and fewer number of cells in the colony of K. contorta. 
 
 Kirchneriella elongata G. M. Smith. PI. 36, Figs. 1-2. 
 
 Bull. Torr. Bot. Cl. 43 : 473, pi. 24, fig. 7. 1916. 
 
 Cells elongate-cylindrical with rounded ends; spirally or irregularly 
 twisted. Colonies of 4-8-16 or more cells arranged in a snarl at the 
 center of a copious homogeneous gelatinous sheath. Chloroplast single, 
 parietal; without a pyrenoid. (Facultative Planktont). 
 
 Cells 2-3 fx broad, 15-25 fx long ; colonies up to 100 fx in diam. 
 
 Devils (2) (rrr). Horse (rrr), Lac Court Orellles (rr). No Mans (rr). 
 Palmer (rr). White Ash (sss). 
 
 Sub-family CRUCIGENIEAE. 
 
 Cells acicular, fusiform, ovoid, triangular, or trapezoidal; in fiat 
 eoenobia with the number of cells always a multiple of two. Cells 
 quadrately arranged in coenobe or in a linear series. Coenobe gener- 
 ally without a gelatinous envelope. Chloroplasts 1-4, parietal, disci- 
 form or laminate ; generally with one pyrenoid. 
 
144 
 
 WISCONSIN PHYTOPLANKTON 
 
 KEY TO THE GENERA. 
 
 Cells quadrately arranged. 
 
 Quadrate arrangement apparent in front view of cells. 
 
 Outer face of cells without spines Crucigenia 
 
 Outer face of cells with spines Tetrastrum 
 
 Quadrate arrangement apparent in end view of cells Tetradesmus 
 
 Cells arranged in a linear series Scenedesmus 
 
 CRUCIGENIA Morren 1830. 
 
 Coenobe free-swimming, of four cells quadrately arranged with a 
 quadrangular open space at the center and frequently connected to 
 other eoenobia by a gelatinous envelope or the remains of the old mother 
 cell walls. Multiple eoenobia forming a flat plate one cell in thickness 
 and containing 4, 16, 32, 64 or more cells. Cells flattened; ovoid, tri- 
 angular, trapezoidal, or semicircular in front view ; with a smooth cell 
 wall. Chloroplasts 1-4, parietal, disciform to laminate, with or with- 
 out pyrenoids. 
 
 Reproduction by autocolony formation, the four cells of the coenobe 
 generally producing autocolonies at the same time. 
 
 KEY TO THE SPECIES. 
 
 Cells apiculate C. Apiculatum 
 
 Cells not apiculate. 
 
 Coenobe with a large rectangular open space at the center. 
 
 Front view of cells trapezoidal C. Fenestrata 
 
 Front view of cells semicircular C. Lauterbornei 
 
 Coenobe with a small open space at the center. 
 
 Length of coenobe greater than the breadth. 
 
 Wall of cell the same thickness throughout. 
 
 Outer face of cells concave C. Cruciata 
 
 Outer face of cells convex. 
 
 Cells of coenobe regularly arranged C. Rectangularis 
 
 Cells of coenobe irregularly arranged C. Irregularis 
 
 Wall of cell thicker at the poles C. Truncata 
 
 Length of coenobe the same as the breadth. 
 
 Cells triangular, with fairly acute corners C. Tetrapedia 
 
 Cells spherical to triangular, with rounded corners C. Quadrata 
 
 Crucigenia rectangularis (Nageli) Gay. PI. 36, Fig. 3. 
 
 Recherches sur le. dev. et la class, de quelques algues vertes 100, pi. 15, fig. 151. 
 1891. 
 
 Coenobe four-celled, cells in mutual contact at the poles and sides 
 and with a small rectangular open space at the center. Generally 
 united in compound eoenobia containing an indefinite number of coen- 
 
WISCONSIN PHYTOPLANKTON 
 
 145 
 
 obes. Cells ovoid to elongate-ovoid, with 1-4 parietal, disciform chloro- 
 plasts, each with a single pyrenoid. Old mother cell wall frequently 
 enclosing young coenobia for some time. (Facultative Planktont). 
 
 Cells 4r-7 /X broad, 5-10 /x long. 
 
 Bear (2) (rr), Beaverdam (rr), Big (rrr), Birch Island (rrr), Devils (1) 
 (r), Fowler (rrr), Half Moon (rr), Hillman (rr), Kegonsa (rr). Lac Court 
 Oreilles (rr), Lindy (rr). Little Bass (2) (rr). Little Doctor (rr). Mill (rrr), 
 Nancy (rr), Nicaboyne (rr), Okauchee (rrr). Old Taylors (rr). Pine Tree 
 (rr). Sand (1) (rr). Upper Nashotah (rrr), Winnebago (rr). 
 
 Crucigenia irregularis Wille. PI. 36, Figs. 4-5. 
 
 Biol. Cent. 18: 302. 1898; Nyt. Mag. f. Naturvidensk. 88: 10, pZ. 1, -fig. 15, 
 1900; W. & G. S. West Trans. & Proc. Bot. Soc. Edinburgh 23: 29, pi. 1, iig$. 
 6-7. 1905. 
 
 Coenobia four-celled, with cells in contact at sides and poles, at other 
 limes without a definite arrangement. Coenobia irregularly combined 
 into multiple coenobia. Cells ovoid ; with 1-4 parietal, disciform chloro- 
 plasts; with or without pyrenoids. (Facultative Planktont). 
 
 Cells 4-9 /X broad, 6-14 /x long. Coenobia 8-14 «, broad, 15-30 /x long. 
 
 Browns (rr). Camp (rr). Fish (rr). Horseshoe (2) (rr), Mudhen (rr). 
 Reserve (rr), Sand (3) (sss). 
 
 The cell shape is quite similar to that of C. rectangularis but the ar- 
 rangement of cells within the coenobe is very irregular in about half 
 the colonies one meets with. This irregular cellular arrangement coup- 
 led with the larger cell size warrants the separation of the alga from 
 C. rectangularis. The alga is generally reported to be without pyre- 
 noids but I have frequently found them in the chloroplasts of C. irregu- 
 laris. 
 
 Crucigenia crucifera (Wolle) Collins. PI. 36, Fig. 6. 
 
 Tufts, coll, studies 2: 170. 1909. 
 
 Staurogenia crucifera Wolle, Bull. Torr. Bot. Cl. 6: 140. 1877. 
 
 Staurogenia cruciatum Wolle, Freshw. Algae of U. S. 171, pi. 157, figs. 9-11. 
 1887. 
 
 Coenobia four-celled, rhomboidal, with rounded ends, slightly con- 
 cave sides, and a small rectangular open space at the center. Cells 
 elongate, outer face concave, inner and those in contact with other cells 
 straight. Chloroplast single, parietal, laminate; without a pyrenoid. 
 (Facultative Planktont). 
 
 Cells 3.5-5 /X broad, 5-7 /x long. Coenobia 9-11 /x broad, 14^16 fx long. 
 
 Hillman (rr). Tenderfoot (rr). 
 
 The arrangement of the individual coenobia into compound coenobia 
 is generally that which Wolle gives in his figure 9 of Staurogenia cruci- 
 
 10 
 
146 
 
 WISCONSIN PHYTOPLANKTON 
 
 atum. Collin’s surmise that the reported cruciform marking of the 
 cell wall is probably due to a division of the cell contents is correct and 
 what Wolle calls the cell is in reality the coenobe. The remains of the 
 old cell walls play an important part in binding together the various 
 coenobia of the multiple coenobe. 
 
 Crucigenia truncata sp. nov. PI. 36, Figs. 7-9. 
 
 Coenobe four-celled, with a small rectangular space at the center and 
 held in compound coenobia of indefinite size by the remains of old 
 mother cell walls. Cells quadrately arranged with bases and middle 
 third of inner sides in mutual contact but with apices and outer faces 
 free. Cells elongate, ovoid, with free ends truncate. Cell wall at free 
 apex thicker than in other parts. Chloroplasts 1-4, parietal, disci- 
 form, without pyrenoids. ( Euplanktont ) . 
 
 Cells 4-6 fi broad, 6-10 fi long. Coenobia 6-12 broad, 12-20 
 fi long. Compound coenobia up to 50x75 fi. 
 
 Chain (rr), Hillman (rr), Pine Tree (rr), Travis (rr). 
 
 The species is differentiated by its flattened cell apices and the thicker 
 walls at the apices. The cells are always regularly arranged within the 
 coenobe, but when in compound coenobia the arrangement is frequently 
 irregular. 
 
 Crucigenia apiculata (Lemmermann) Schmidle. PI. 37, Fig. 1. 
 Allg. Bot. Zeitschr. 6: 234. 1900. 
 
 Staurogenia apiculata Lemmermann, Bot. Cent. 76: 151. 18'98; For- 
 
 Bchungsbr. a. d. Biol. Stat. zu Plon 7: 119, pi. 1, fig. 14. 1899; Snow, Bull. 
 U. S. Fish Comm. 22: 376, pi. 1, figs. V^V«. 1903. 
 
 Tetrastrum apiculatum (Lemmermann) Brunnthaler, in Pascher, Siisswas- 
 serfl. Deutschl., Osterr. u. d. Schw. 5^: 177, fig. 258. 1915; G. M. Smith, Bull. 
 Torr. Bot. Cl. 43 : 472, pi. 24, fig. 3. 1916. 
 
 Coenobia four-celled, embedded in a delicate gelatinous sheath. Cells 
 quadrately arranged with their long axes parallel and a small rectangu- 
 lar space at the center. Coenobia generally in multiple coenobia which, 
 when containing large numbers of coenobia, are frequently irregular. 
 Cells ovoid to triangular, with a short conical projection at the free 
 apex and frequently another one at the side of the base away from the 
 center of the coenobe. Each cell containing 1-4 parietal disciform 
 chloroplasts with one pyrenoid. (Euplanktont). 
 
 Cells 3-7 /A broad, 5-10 fi long. Coenobia 6-12.5 fx broad, 9-18 
 /i long. Compound coenobia up to 150 p, broad. 
 
 Mendota (rrr). Palmer (rrr), South Crab (rr). 
 
 The cells of 16-celled multiple coenobia are regularly arranged but 
 when multiple coenobia contain 150-200 cells the arrangement is fre- 
 
WISCONSIN PHYTOPLANKTON 
 
 147 
 
 quently irregular. The gelatinous sheath enclosing the colony is very 
 delicate and can only be seen when properly stained. This species was 
 placed in the genus Tetrastrum in a preliminary list, but it is more 
 closely related to Crucigenia than to Tetrastrum. 
 
 Crucigenia quadrata Morren. PI. 36, Figs. 10-14. 
 
 Ann. Sci. Nat. 20: 415, pi. 15, figs. 1-5. 1830. 
 
 Staurogenia triangularis Chodat, Mem. Herb. Boiss. 1, No. 17 : 7, figs. 14-19. 
 1900. 
 
 Crucigenia triangularis (Chodat) Schmidle, Allg. Bot. Zeitschr. 6: 234. 1900. 
 
 Staurogenia multiseta var. punctata Schmidle, Ber. d. D. bot. Ges. 18: 157, 
 pi. 6, figs. 13-14. 1900. 
 
 Coenobia four-celled, circular in outline. Cells in mutual contact at 
 or with very small rectangular openings at center of the coenobe. 
 Four coenobia compressed to form rectangular multiple coenobia which 
 in turn are joined to other sixteen-celled multiple coenobia. Cells 
 spherical to triangular; with a smooth wall or with 1-6 minute knob- 
 like projections on the wall. Chloroplasts 1-4, parietal, disciform, with 
 or without pyrenoids. (Facultative Planktont) . 
 
 Cells 2.5-6 fL broad, 3-7 p, long. Coenobia 5.5-17 /x in diam. 16- 
 celled compound coenobia 12-30 /x in diam. 
 
 Carson (rrr). Chain (rr), Hillman (sss). Kitten (rrr), Lac du Flambeau 
 (rr). Palmer (sss), Pardee (rr). Tenderfoot (rrr). White Sand (rrr). 
 
 Pyrenoids are very prominent in the chloroplasts of certain colonies 
 while other colonies collected from the same station show no trace of 
 them. In some of the colonies from Hillman lake small, globular, but- 
 ton-like structures were observed on the cell walls. Such structures 
 have been noted by Schmidle and form the distinctive character of his 
 variety punctata of Staurogenia multiseta [Tetrastrum multisetum 
 (Schmidle) Chodat]. If the variety is to be recognized it should be 
 called C. quadrata var. punctata (Schmidle) but I am of the opinion 
 that it is not a sufficiently constant character to warrant recognition. 
 There is likewise no justification for considering C. triangularis (Cho- 
 dat) Schmidle a distinct species since it does not differ in any respect 
 from C. quadrata. 
 
 Crucigenia tetrapedia (Kirchner) W. & G. S. West. PI. 37, Fig. 2. 
 
 Trans. Roy. Irish Acad. 32, Sec. B: 62, pi. 1, figs. 11-12. 1902. 
 
 Staurogenia tetrapedia Kirchner, Jahreshefte d. Ver. f. Vaterl. Naturk. i. 
 Wiirttemberg 1880, pi. 2, fig. 1. 
 
 Tetrapedia emarginata Schroder, Ber. d. D. bot. Ges. 15: 492, pi. 25, figs. 
 6a-6c. 1897. 
 
 Lemmermannia emarginata (Schroder) Chodat, Mem. Herb. Boiss. 1, No. 
 IT; figs. 1-^. 1900. 
 
148 
 
 WISCONSIN PHYTOPLANKTON 
 
 Lemmermannia tetrapedia (Kirchner) Lemmermann, Arkiv. for Botanik 2, 
 No. 2: 157. W04. 
 
 Coenobia four-celled, with a very small rectangular open space at 
 the center. Frequently joined in multiple coenobia of sixteen -cells that 
 may be connected in turn to other 16-celled multiple coenobia. Cells 
 flattened, triangular, with rounded corners. Cell contents homogeneous, 
 or with a single parietal chloroplast, with or without pyrenoids. (Fac- 
 ultative Planktont). 
 
 Diam. cells 4.8-9.5 /x; diam. coenobia 8-15 /x; diam. 16-celled multiple 
 coenobia up to 40 /x. 
 
 Palmer (rr). 
 
 Certain investigators have noted that the cell contents are at times 
 absolutely homogeneous. This has caused Schroder to consider the alga 
 a species of Tetrapedia, one of the Myxophyceae, but the Wests have 
 given cogent reasons for considering it a Crucigenia. 1 have found a 
 distinct parietal chloroplast and pyrenoid in the cells whereas Chodat 
 states that there is a chloroplast but no pyrenoid. His founding of the 
 genus Lemmermannm upon this single character (lack of a pyrenoid) 
 has rightly been called by G. S. West (Brit. Freshw. Algae 217. 1904) 
 ‘‘the climax of absurdity.” 
 
 Crucigenia fenestrata Schmidle. PI. 37, Fig. 3. 
 
 Allg. Bot. Zeitschr. 6: 234. 1900. 
 
 Staurogenia fenestrata Schmidle, Allg. Bot. Zeitschr. 3: 107, fig. 1. 1897. 
 
 Coenobia four-celled, rectangular, with a medium-sized opening at 
 tile center; with an inconspicuous gelatinous sheath. Frequently in 
 multiple coenobia with the component coenobia lying close together. 
 Cells trapezoidal, with the longest face at the outside of the coenobe. 
 Chloroplast single, except just before division, parietal, without a pyre- 
 noid ( ? ) . ( Euplankt ont ) . 
 
 Cells 3-5 fx broad, 5-12 /x long ; coenobia 8-14 /x broad. 
 
 Bettine (rr). White Sand (rr). 
 
 The specimens that I have found do not agree in all respects with 
 Schmidle ’s description since there was no gelatinous sheath surround- 
 ing the coenobe and filling the central space. 
 
 Crucigenia Lauterbornei Schmidle. PI. 37, Fig. 4. 
 
 Allg. Bot. Zeitschr. 6: 234. 1900. 
 
 Staurogenia Lauterbornei Schmidle, Allg. Bot. Zeitschr. 2: 192, fig. 1. 1896. 
 
 Coenobia four-celled, cells in contact with one another at their apices 
 only and with a large square open space at the center of the coenobe. 
 
WISCONSIN PHYTOPLANKTON 
 
 149 
 
 Coenobia joined in multiple coenobia of at least sixteen cells by the re- 
 mains of old cell walls and a gelatinous envelope. Cells flattened, sub- 
 hemispherical in front view with the flattened side towards the center 
 of the coenobe. Chloroplast single, parietal, on the outer face of the 
 cell; with one pyrenoid. (Euplanktont). 
 
 Cells 4.5-9 fx broad, 8-15 /x long. Coenobia 15-25 /x in diam ; multiple 
 coenobia up to 150 fx in diam. 
 
 Kegonsa (r), Fokegama (rr), Rice (1) (r), Upper Turtle (r). 
 
 A very distinct species and one that is readily recognized by the large 
 opening at the center of the colony. C. fenestrata also has a large, rec- 
 tangular open space at the center of the coenobe but the two species 
 have quite differently shaped cells ; those of C, Lauterhornei being semi- 
 circular in front view, and those of C. fenestrata trapezoidal. 
 
 TETKASTRUM Chodat 1895. 
 
 Coenobia four-celled, with cells cruciately arranged in a flat plate; 
 at times embedded in a thin gelatinous envelope. Cells triangular to 
 ovoid, with several spines or setae on the free face. Chloroplasts 1-4, 
 parietal, disciform, with or without pyrenoids. 
 
 Reproduction by autocolony formation in any cell. 
 
 The genus is closely related to Crucigenia, differing only in the spines 
 on the margins of the cells and an absence of an association in multiple 
 coenobia. 
 
 Tetrastrum staurogeniaeforme (Schroder) Lemmermann. PI. 37, 
 
 Figs. 5-6. 
 
 Ber. d. D. bot. Ges. 18: 95. 1900. 
 
 Cohniella Staurogeniaeformis Schroder, Ber. d. D. bot. Ges. 15: 373, pZ. 17, 
 ftg. 5. 1897. 
 
 Coenobia four-celled, with a very minute open space at the center 
 of the colony. Coenobe embedded in a very delicate gelatinous envelope. 
 Cells cruciately arranged, triangular, with 5-6 very delicate setae on 
 the free surface. Chloroplasts 1-4, parietal, disciform, with or without 
 pyrenoids. ( Euplanktont) . 
 
 Diam. cells (without setae) 3-6 fx; diam. coenobia (without setae) 
 7-15 /X. Setae 4-8 fx long. 
 
 Horse (rr), Mendota (rrr). 
 
 The setae on the outer face of the cells are very delicate and easily 
 overlooked. If the setae are not taken into consideration the alga looks 
 exactly like Crucigenia quadrat a. 
 
150 
 
 WISCONSIN PHYTOPLANKTON 
 
 TETRADESMUS G. M. Smith 1913. 
 
 Colonies free-floating, four-celled, rarely two- or three-celled. Cells 
 in two planes with two cells in each plane and joined along the long 
 axes when the colony is viewed from the side. Viewed from the top 
 cells quadrately arranged. Cells elliptic-fusiform to broadly elliptic, 
 with outwardly divergent or straight apices. Chloroplast single, pari- 
 etal and laminate or completely filling the cell ; pyrenoid single, central 
 or eccentric. 
 
 Reproduction by autocolony formation in any cell of the colony, the 
 young coenobia being liberated by a rupture of the mother cell wall. 
 
 Tetradesmus wisconsinensis G. M. Smith. PI. 37, Figs. 7-11. 
 Bull. Torr. Bot. Cl. 40: 76, pi. 1, figs. 1-2, 3-20. 1913. 
 
 Cells elliptic-fusiform, apices attenuated and outwardly divergent. 
 Pyrenoids eccentric. (Facultative Planktont). 
 
 Cells 4^6 fji broad, 12-14.5 fx long. 
 
 Blake (rrr), Mendota (rr), Nancy (rrr). 
 
 SCENEDESMUS Meyen 1829. 
 
 Coenobe a flat (rarely curved) plate of ellipsoidal, ovoid, or acicular 
 cells with cell number always a multiple of two. Cells in lateral con- 
 tact and in one or two rows. Cell wall smooth, corrugated, granulate, 
 or spicate ; with or without marginal or lateral teeth or spines. Chloro- 
 plast single, parietal, and laminate in young cells; frequently filling 
 entire cell in older colonies ; pyrenoids single, central or eccentric. 
 
 Reproduction by autocolonies from any or all cells of the coenobe, 
 the number of cells in the colony not necessarily the same as that of 
 the mother colony. 
 
 KEY TO THE SPECIES. 
 
 Walls smooth, without granulations, lateral ridges, terminal teeth or spines. 
 
 Cells acicular to broadly elliptic, with pointed ends. 
 
 Colony a flat plate. 
 
 All cells in colony erect S. Obliqutjs 
 
 Median cells erect, terminal cells lunate S. Dimoephus 
 
 Colony a curved or twisted plate. 
 
 Cells forming a curved surface S. Acuminatus 
 
 Cells alternately arranged with terminal cells not in the 
 
 same plane as the others S. Beenardu 
 
 Cells ovoid to cylindrical, with rounded ends. 
 
 Arrangement of cells a single linear or subalternating but 
 
 never a double series S. Bijuoa 
 
 Arrangement of cells a double linear series S. Arcuatus 
 
WISCONSIN PHYTOPLANKTON 
 
 151 
 
 Wall variously sculptured or ridged, at times with terminal teeth or spines. 
 
 Longitudinal ridges on sides of the cells. 
 
 Without terminal teeth or spines S. Acutiformis 
 
 With terminal teeth or spines. 
 
 Terminal cells with long spines at poles S. Aematus 
 
 All cells with short teeth at poles S. Brasiliensis 
 
 Longitudinal ridges not present on sides of the cells. 
 
 Teeth-like spines covering entire wall S. Hystrix 
 
 Teeth or spines confined to poles, outer face of terminal 
 cells, or middle of all cells. 
 
 Cells with short teeth at poles S. Denticulatus 
 
 Cells with long spines. 
 
 Spines on both median and terminal cells. 
 
 Poles of cells only region bearing spines. 
 
 Cells ovoid to ovoid-cylindrical S. Longus 
 
 Cells naviculoid S. Opoliensis 
 
 Poles and median part of cells bearing spines S. Abundans 
 
 Spines confined to terminal cells. 
 
 Cells ovoid to ovoid-cylindrical S. Qtjadricauda 
 
 Cells naviculoid S. Opoliensis 
 
 SCENEDESMUS OBLIQUES (Turpin) Kiitzing. PI. 37, Figs. 12-14. 
 Linnaea 8: 609. 1833; G. S. West, Brit. Freshw. Algae 220, fig. 92a. 1904. 
 
 Cells of 2-4-8 cells arranged in a single linear or sublinear series. 
 Cells fusiform, with acute apices ; interior cells with straight sides, outer 
 face of terminal cells slightly concave, straight, or convex. Cell wall 
 smooth, without terminal teeth or spines. (Tychoplanktont). 
 
 Cells 3-9 /X broad, 10-21 /x long. 4-celled coenobia 10-21 /x broad, 
 12.5-24 fjL long. 
 
 Balsam (rrr). Bear (1) (rrr), Blake (rr). Bone (rr). Grassy (rr), Hill- 
 man (rrr). Horseshoe (2) (rrr), Lindy (rr). Little Bear (rrr). Little Doctor 
 (rr). Little Rice (2) (rrr). Loon (rr), Mendota (rrr), Pewaukee (rrr). Poor 
 Farm (rrr). Pope (rrr). Rice (2) (rr). Sand (3) (rrr). Sand (4) (rrr). Up- 
 per Nemahbin (rrr). White Ash (rrr). 
 
 ScENEDESMUS DiMORPHUS (Turpin) Kiitzing. PI. 37, Figs. 15-17. 
 
 Linnaea 8 : 608. 1833; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18 ' : 
 434, pi. 32, figs. 185-189; pi. 33, figs. 190-195. 1916. 
 
 Coenobia of four or eight cells arranged in a linear or alternating 
 series. Cells fusiform with apices attenuated to delicate points. In- 
 terior cells erect, outer erect or markedly lunate. Cell wall smooth, 
 without terminal teeth or spines. (Facultative Planktont). 
 
 Cells 2-5 /X broad, 18-23 /x long. 4-celled coenobia 18-23 fx broad, 
 12-25 fx long. 
 
 Dunham (rrr). Horse (r), Pine Tree (sss), Poor Farm (ss), Travis (sss). 
 
152 
 
 WISCONSIN PHYTOPLANKTON 
 
 The outwardly turned lunate terminal cells, together with the pro- 
 nounced alternate arrangement distinguishes this species from the fore- 
 going. I have given elsewhere (1. c.) the reasons for considering this 
 a distinct species and not a variety of S. obliquus, 
 
 SCENEDESMUS ACUMiNATus (Lagorheim) Chodat. PI. 38, Figs. 1-4. 
 
 Mater, pour la fl. crypt. Suisse 1": 211. 1902. 
 
 Selenastrum acuminatum Lagerheim dfvers. Kgl. Vet.-Ak. Forh. S9: No. 2: 
 71, pi. 3, figs. 27-30. 1882. 
 
 Coenobia curved, of 4 or 8 (generally 4) cells. All of the cells of a 
 colony arcuate or lunate, fusiform, with the ends gradually tapering 
 to a fine point. Cell wall smooth, without teeth, granulations or spines. 
 (Facultative Planktont). 
 
 Cells 3-7 fjL broad, 30-40 fi between apices. 
 
 Horse (sss). 
 
 This species should not be confused with Selenastrum acuminatus 
 G. S. West non Lagerheim, a species which I have already discussed 
 in connection with Selenastrum Westii G. M. Smith. 
 
 ScENEDESMUS Bernardii G. M. Smith. PI. 38, Figs. 5-9. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18^: 436, pi. 33, figs. 196-208. 1916. 
 
 Colonies of 2-4-8 cells. Interior ceils fusiform, lunate or sigmoid, 
 with acute apices; alternately arranged with apices in contact with 
 apices or median portion of adja.cent cells. Terminal cells fusiform to 
 lunate, frequently at an angle to the plane of the coenobe, in contact 
 Avith the interior cells by the apex only. Cell wall smooth, without 
 terminal spines or teeth. ( Tychoplanktont ?). 
 
 Cells 3-6 fl broad, 8-17 /x long. 
 
 Monona (rrr). 
 
 ScENEDESMUS BiJUGA (Turpin) Lagerheim. PI. 37, Pigs. 18-20. 
 Nuova Notarisia 1893: 158. 1893. 
 
 Scenedesmus hijugatus (Turpin) Kiitzing. G. S. West, Brit. Freshw. Algae 
 220, fig. 92c. 1904. 
 
 Coenobes flat, of 2^r-8 cells in a single (rarely subalternate) series. 
 Cells oblong-elliptic to ovoid, with broadly rounded ends. Cell wall 
 smooth, Avithout teeth or spines. (Tychoplanktont). 
 
 Cells 4-7 fl broad, 7-18 fi long. 4-celled colonies 7-18 fi broad, 16-25 
 fl long. 
 
 Fowler (rrr), Lindy (rr), Little Bice (2) (rr). Mill (rr). Poplar (rrr), 
 Silver (2) (rr), Streitor (rr). Upper Turtle (rrr). Wolf (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 153 
 
 var. ALTERNANs (Reinsch) Borge. PI. 38, Figs. 10-11. 
 
 Ai-kiv. for Botanik 6, No. 1: 57. 1906. 
 
 Scenedesmus alternans Reinsch, Abh. Senckenb. Naturf. Ges. 6: 135, pi. 20, 
 ng. D‘. 1866. 
 
 Colonies flat, generally 8-celled, with a very marked alternate ar- 
 rangement of the component cells. Cells ovoid to elliptic. (Tycho- 
 planktont). 
 
 Cells 4-8 fjL broad, 6-15 /x long. 8-celled coenobia 12-30 /x broad, 
 22^5 /X long. 
 
 Blake (rr). Devils (1) (rrr), Muskallonge (rr). 
 
 Since cultural studies have shown that the alternate arrangement of 
 cells is a constant character it is proper to consider this a distinct vari- 
 ety. The variety has also been found in lakes where the typical form 
 is absent. 
 
 Scenedesmus arcuatus Lemmermann. PI. 38, Figs. 12-14. 
 Forscbungsbr. a. d. Biol. Stat. zu Plon 7: 112, pi. 1, figs. 2-4. 1899. 
 
 Colonies always curved, of 4r-8-16 (generally 8) cells arranged in a 
 double row. Cells ovoid, sometimes angular by mutual compression 
 at the base. -Coenobia with small interstices between the cells. Cell 
 wall smooth, without spines or teeth. (Euplanktont). 
 
 Cells 3-9 /X broad, 9-17 /x long. 8-celled coenobia 15-25 /x broad, 
 15-40 /X long. 
 
 Beaverdam (rr), Blake (rrr), Camp (rrr). Center (ss). Chain (rr), 
 Cochrane (rr), Cranberry (rr), Hillman (r). Lac Court Oreilles (rr). Lac du 
 Flambeau (rr). Little Bass (2) (rr). Little Crooked (rr). Long (1) (rrr). 
 Long (3) (rr). Lower Turtle (rr), Mendota (sss), Meta (rrr). North Turtle 
 (rr), Owen (rrr). Paddock (rrr). Palmer (rrr), Pardee (rr), Pokegama (2) 
 (rr). Reserve (rr). Round (1) (rrr). Sand (1) (rrr). Sand (4) (rrr). Shell 
 (rrr), Sishebogema (rr). Tied Canoe (rr). Upper Turtle (rr). Wolf (r). 
 
 One of the few species of the genus that is exclusively confined to 
 the plankton. The curving of the coenobe and the double series of 
 ovoid cells at once separates it from all other species. 
 
 var. CAPiTATUS G. M. Smith. PI. 38, Figs. 15-16. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 637, pi. 11, figs. 4-5. 1918. 
 
 Cells with nodular thickenings at the poles. (Euplanktont). 
 
 Cells 5-11 /X broad, 11-23 /x long. 8-eelled colonies 22-27 /x broad, 
 20-35 /X long. 
 
 Center (rr). 
 
154 
 
 WISCONSIN PHYTOPLANKTON 
 
 var. PLATYDISCA G. M. Smith. PL 39, Figs. 1-3. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18*: 451, pZ. 30, figs. 101-105. 1916. 
 
 Colonies always flat, generally 8-celled. Cells oblong-elliptic and 
 arranged in a double series. Coenobia with small interstices between 
 the cells. (Facultative Planktont). 
 
 Cells 4.5-T.5 ix broad, 8-17 fx long. 8-celled coenobia 11-30 fx broad, 
 18-30 [X long. 
 
 Camp (rrr). Eagle (rr), Fowler (rr), George (rr). Horse (rrr), Kegonsa 
 (ss). Paddock (rr). Pine (1) (rr). 
 
 An alga that has been considered a normal variation of S. hijuga but 
 one which, as stated elsewhere (1. c.), seems more closely related to 
 S. arcxmtus. 
 
 ScENEDESMus ACUTiFORMis Schroder. PL 39, Figs. 4-6. 
 Forschungsbr. a. d. Biol. Stat. zu Plon 5: 45, pZ. 2, figs. 4a-4b. 1897. 
 
 Coenobia flat, of 2-4-8 (generally 4) cells arranged in a linear series. 
 Cells fusiform, with acute apices. Cell wall of interior cells with a 
 single ridge that extends from pole to pole on each side ; wall of termi- 
 nal cell with 2-4 ridges. Poles of cells without spines or teeth. (Fac- 
 ultative Planktont). 
 
 Cells 5-8 ix broad, 16-22 fx long. 4-celled colonies 16-22 fx broad, 
 20-25 fx long. 
 
 Mendota (rr). Rice (1) (rrr). 
 
 Only a single longitudinal ridge can be seen in a front view of the 
 cell but the number of ridges is readily ascertained in an end view of 
 cells. The presence of these ridges without accompanying spines or 
 teeth separates this from other species. 
 
 ScENEDESMUs ARMATUS (Chodat) G. M. Smith. PL 39, Figs. 7-10. 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18*: 460, pi. 29, figs. 90-93. 1916. 
 
 Coenobia of 2-4^8 cells arranged in a linear or subalternating series. 
 Cells ovoid to oblong-ellipsoid; with rounded apices. Terminal cells 
 with a single long spine at each pole. Both sides of cells with a longi- 
 tudinal ridge that may extend from pole to pole but is generally indis- 
 tinct in the median portion of the cell. (Facultative Planktont). 
 
 Cells 4-7 fx broad, 7-16 fx long. 4-celled coenobia (without spines) 
 7-16 fx broad, 16-25 fx long. Spines 5-7 /a long. 
 
 Bear (2) (rr). Bear Trap (rrr). Bone (rr). Browns (rr), Carson (rr). Fish- 
 trap (rrr). Horseshoe (2) (rr). Lac Court Oreilles (rr). Little Butternut (rrr), 
 Little Crooked (rr). Loveless (rr). Lynx (rrr), Mendota (rrr), Pardee (rrr). 
 Pine Tree (rr), St. Croix (rrr), Silver (rr). Upper Turtle (rrr). Wolf (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 155 
 
 var. major var. nov. PI. 39, fig. 11. 
 
 Cells up to 9 broad and 25 /i long. Spines 15 long. (Facultative 
 Planktont ?). 
 
 Palmer (rr). 
 
 ScENEDESMUS BRASiLiENSis Bohlin. PI. 39, Figs. 12-14. 
 
 Bill. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 22, pi. 1, figs. 36-37. 1897. 
 
 Coenobia flat, of 2^:-8 (generally 4) cells arranged in a single linear 
 series. Cells cylindrical to ovoid-ellipsoid, with a single longitudinal 
 ridge extending from pole to pole on each side of the cell. Poles with 
 1-4 small teeth. (Facultative Planktont). 
 
 Cells 3-6 fi broad, 11-24 fi long. 4-celled coenobia 11-24 p. broad, 
 12-25 long. 
 
 Bear (2) (r), Beaverdam (rrr), Chain (rrr), Clare (rrr), Deer (rrr), Jag 
 (rr), Lac du Flambeau (rrr). Lake of the Woods (rrr), Lindy (rr). Little 
 Doctor (rr). Old Taylors (rr). Pine (2) (rr). Rice (1) (rr). White Sand (rrr). 
 
 The species may be distinguished from S. denticuLatus by the linear 
 ridges on the sides of the cells. 
 
 ScENEDESMUS HYSTRix Lagerheim. PI. 39, Figs. 15-16. 
 dfvers. Kgl. Vet.-Ak. Porh. 39, No. 2: 62, pi. 2, fig. 18. 1882. 
 
 Coenobia flat, of 2-4^8 cells joined in a single linear series. Cells 
 oblong-cylindrical, with blunt conical apices. Entire surface of cells 
 covered with minute spines. (Tychoplanktont). 
 
 Cells 3-5 IX broad, 8-18 [x long. 4-celled coenobia 8-18 fx broad, 12- 
 25 fx long. 
 
 Rudolph (rrr). 
 
 ScENEDESMUS DENTICULATUS Lagerheim. PI. 39, Figs. 17-19. 
 Ofvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 61, pi. 2, figs. 13-17. 1882. 
 
 Coenobia flat, generally four-celled. Cells ovoid to ovoid-ellipsoid, 
 arranged in a linear or subalternating series. Poles of cells without 
 ridges but with 1-4 short spines. (Facultative Planktont). 
 
 Cells 5-11 fx broad, 7-15 fx long. 4-celled coenobia 7-15 fx broad, 
 15-22 fx long. 
 
 Amicoy (rr). Bear (2) (rr). Browns (rr). Chain (rr). Deer (rrr). High (r), 
 Hillman (rr). Horse (rrr). Horseshoe (2) (rr). Lac du Flambeau (rrr), Lit- 
 tle Doctor (rrr). Silver (3) (rr). White Ash (rr). Wolf (rr). 
 
156 
 
 WISCONSIN PHYTOPLANKTON 
 
 ScENEDESMUs LONGUS Meyen. PI. 39, Figs. 20-22. 
 
 Nova Acta Phys.-Med. Acad. Caes. Leop. Nat. Cur. 14: 774, pi. 43, fig. 28. 
 1829. G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18": 469, pi. 31, figs. 
 156-158. 1916. 
 
 Scenedesmus quadricauda var. setosus (Kirchner) Lagerheim, 5fvers. Kgl. 
 Sv Vet.-Ak. Forh. 39, No. 2: 63. 1882. 
 
 Coenobe flat, of 2-4-8 (generally 4) cells arranged in a single linear 
 series. Cells ovoid to oblong-cylindrical, with rounded poles. Poles 
 of all cells with 1-2 spines. Cell wall destitute of spines except at the 
 poles. ( Tychoplanktont) . 
 
 Cells 4-5 fi broad, 8-11 long. 4-celled coenobia 8-11 fx broad, 16- 
 20 jx long. 
 
 Rock (rr). 
 
 var. Naegelii (Brebisson) comb. nov. PL 40, Figs. 1-2. 
 
 Scenedesmus Naegelii de Brebisson, Mem. de la soc. Imp. de Sc. Nat. de 
 Cherbourg 4: 158. 1856. 
 
 Scenedesmus eaudatus Nageli non Corda, Gatt. einz. Algen 91, pi. 5, figs. 
 2c-2d. 1849. 
 
 Colonies flat, always eight-celled. Cells cylindrical, with rounded 
 poles. Terminal cells with spines at both poles, interior cells with 
 spines at one pole, rarely at both poles. (Facultative Planktont). 
 
 Cells 6.6-11 /X broad, 18-33 /x long. 8-celled colonies 18-33 /x broad, 
 50-85 /X long. 
 
 Blake (rr). Camp (rrr). Poor Farm (rrr). White Ash (rr). 
 
 This alga was described by de Brebisson from the drawings of 
 /S». quadricauda by Nageli. In my monograph of Scenedesmus I in- 
 cluded it as a synonym of S. longus (Trans. Wis. Acad. Sci., Arts, & 
 Lett. 18^: 469. 1916) but am now convinced that it should be con- 
 sidered a distinct variety. The cells are much larger than the typical 
 form but unfortunately Nageli gives neither measurements for the cells 
 nor an indication of the scale of magnification of his drawings. The 
 measurements stated above are those of cells from Wisconsin lakes. 
 The peculiar arrangement of the spines that Nageli figures, where three 
 adjacent interior cells have spines on the same end and none on the 
 other with the reverse condition in the remaining interior cells, was 
 found to be a common but not a constant character since specimens were 
 found with spines at both poles of interior cells. 
 
WISCONSIN PHYTOPLANKTON 
 
 157 
 
 ScENEDESMUs ABUNDANS (Kirchner) Chodat. PI. 39, Figs. 23-25. 
 
 Mater, p. la fi. crypt. Suisse. 4*: 77. 3913; G. M. Smith, Trans. Wis. Acad. Sci., 
 Arts, & Lett. 18^: 465, pi, 31, /ips. 137-140, 1916. 
 
 Scenedesmus quadricauda var. ahundans (Kirchner) Lagerheim, 5fvers. 
 Kgl. Vet.-Ak. Forh. 39, No. 2: 64, pi. 2, fig. 20. 1882. 
 
 Coenobe flat, generally 4-celled. Cells ovoid to oblong-ellipsoid. 
 Terminal cells with 1-2 spines at poles and additional spines on outer 
 face between the poles. Interior cells with 1-2 spines at each pole. 
 (Facultative Planktont). 
 
 Cells 4r-7 /A broad, 7-12 ix long. 4-celled coenobia 7-12 fx broad, 
 15-30 fx long. Spines 4r-7.5 {x long. 
 
 Beaver (2) (rr), Cochrane (rr). Diamond (rr). Grassy (rr), Horse (rr), 
 Long (1) (rrr), Nancy (rrr). Palmer (rr). Poor Farm (ss). 
 
 var. LONGiCAUDA G. M. Smith. PI. 39, Figs. 23-27. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18^: 467, pi. 30, -figs. 121-125. 1916. 
 
 Cells smaller, ovoid. Spines much longer in proportion to the size 
 of the cells. (Facultative Planktont). 
 
 Cells 3-6 fx broad, 7-9 fx long. 4-celled coenobia 7-9 fx broad, 10-15 
 fx long. Spines 6-10 (x long. 
 
 Camp (rr), Chain (rrr). Horse (rr). White Ash (rr). 
 
 var. BREViCAUDA G. M. Smith. PI. 40, Figs. 3-5. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18': 468, pi. 30, figs. 126-132. 1916. 
 
 Cells ovoid, smaller. Spines much shorter and never more than 
 three between the polar spines of terminal cells. (Facultative Plank- 
 tont). 
 
 Cells 2.5-5 fx broad, 5-8 fx long. 4-celled coenobia 5-8 fx broad, 
 10-13 fx long. Spines 1.5-3 .5 fx long. 
 
 Mendota (rr). 
 
 var. ASYMMETRiCA (Schroder) G. M. Smith. PL 40, Figs. 6-8. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18': 468, pi. 27, figs. 45-46. 1916. 
 
 Scenedesmus quadricauda var. asymmetrica Schroder, Forschungsbr. a. d. 
 Biol. Stat. zu Plon 5: 45, pi. 2, figs. 5a-5c. 1897. 
 
 Coenobia generally 4-celled, with oblong-ellipsoid cells. Poles of 
 terminal cells with a single spine. All cells of coenobe with a single 
 median spine perpendicular to the plane of the coenobe and at one 
 side of cell only. (Facultative Planktont). 
 
 Cells 2.5-4.5 y. broad, 12-15 y long. 4-celled coenobia 12-15 y broad, 
 13-18 y long. Spines 7-10 y long. 
 
 Blue Gill (rr). Wild Goose (rrr). 
 
158 
 
 WISCONSIN PHYTOPLANKTON 
 
 ScENEDESMUS QUADRicAUDA (Turpin) de Brebisson. PI. 40, Figs. 9-11. 
 
 Mem. de la Soc. Ac. de Falaise 1835: 66. 1835; G. S. West, Brit. Preshw. Algae 
 220, -figs. 92D-92F. 1904. 
 
 Coenobia flat, of 2-4-8-16 (generally 4) cells in a simple linear or 
 snbalternating series. Cells cylindrical-ovoid, with rounded poles. Poles 
 of terminal cells with a single long straight or curved spine. Poles of 
 interior cells without spines. (Facultative Planktont). 
 
 Cells 3.5-6 [X broad, 11-16 /a long. 4-celled coenobia 11-16 /a broad, 
 12-23 /A long. Spines 10-12 /a long. 
 
 Beaverdam (rr). Big Butternut (rrr), Blake (rr). Browns (rr). Camp (rr), 
 Cketek (rr). Clam (rr). Clear (rr). Eagle (rr). East (rrr), Fislitrap (rr). 
 Green (1) (rr), Hillman (rr). Horseshoe (2) (rr). Lac du Flambeau (rr), 
 Lindy (rr). Little Rice (2) (r). Lost (rr), Loveless (rr), Lower Nashotah 
 (rr). Lower Nemahbin (rr), Mary (rr), Meta (rr). Mud (1) (rr). Mud (2) 
 (rr), Muskallonge (r), Nancy (rr), Okauchee (rrr). Old Taylors (rr) Poke- 
 gama (1) (rr),Pope (rr). Poplar (rr). Poor Farm (sss), Rice (1) (rr). Round 
 (3) (rr), Sand (1) (rrr). Sand (4) (rr), Travis (ccc). White Ash (rr), Wild 
 Goose (rrr), Winnebago (rr). 
 
 The most ubiquitous species of the genus. The presence of spines 
 on the poles of the terminal cells only is the distinguishing feature of 
 the species. Cultural work has shown that it is possible to recognize 
 several distinct varieties of this species. 
 
 var. PARVUS G. M. Smith. PI. 40, Fig. 17. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18": 480, pZ. 31, Ms. 162-166. 1916. 
 
 Cells ovoid-cylindrical. Length of cells 2-2.5 times the breadth and 
 equal to the length of the spines. (Tychoplanktont). 
 
 Cells 3-4 IX broad, 5.5-8 /a long. 4-celled coenobia 5.5-8 /a broad, 
 12-15 IX long. Spines 4.5-8 /a long. 
 
 Deer (rrr). 
 
 var. QUADRisPiNA (Chodat) G. M. Smith. PI. 40, Figs. 15-16. 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18": 479, pi. 31, figs. 167-171. 1916. 
 
 Cells broadly ovoid, about twice as long as broad. Spines short, 
 about as long as the diameter of the cell. (Tychoplanktont). 
 
 Cells 3.5-8 fx broad, 8.5-15 /a long. 4-celled coenobia 8.5-15 ^ broad, 
 16-32 fx long. Spines 2.5-5.5 /a long. 
 
 Mill (rrr). Pine (rr), Pokegama (1) (rrr), Round (1) (rr). Tied Canoe 
 (rrr). 
 
WISCONSIN PHYTOPLANKTON 
 
 159 
 
 var. LONGiSPiNA (Chodat) G. M. Smith. PI. 40 , Figs. 12 - 14 . 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18 ": 480, pi. 31, figs. 159-161. 1916. 
 
 Cells ovoid-cylindrical. Length of cells 2.5 times the breadth. (Fac- 
 ultative Planktont). 
 
 Cells 3.5-5 p, broad, 8-11 jx long. 4-celled coenobia 8-11 /x broad, 
 12-20 fx long. Spines 7.5-10 fx long. 
 
 Horse (rr). Lost (rr), Mendota (sss). Palmer (r). 
 
 var. Westii G. M. Smith. PI. 41, Pigs. 3-7. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 18 ": 480, pi. 32, figs. 177-180. 1916. 
 
 Cells 4.5-8 fx broad, 16-22 p. long. 4-celled coenobia 16-22 p broad, 
 25-35 p long. Spines 12-16 p long. (Facultative Planktont). 
 
 Bear Trap (rrr), Blake (rr). Camp (rr), Cochrane (rr), Crawling Stone 
 (rr), Grassy (rr). Horse (rrr), Lac Court Oreilles (rr). Loon (rrr), Meta 
 (rr), Silver (2) (rr). 
 
 var. MAXIMUS W. & G. S. West. PI. 41 , Figs. 1 - 2 . 
 
 Trans. Linn. Soc. 2 Ser. Bot. 5: 83, pi. 5, figs. 9-10. 1895. 
 
 Cells much larger and spines proportionally longer. (Facultative 
 Planktont). 
 
 Cells 9-11.5 p broad, 27-36 p long. 4-celled coenobia 27-36 p broad, 
 35^0 p long. Spines 20-30 p long. 
 
 Eagle (rr), Nicaboyne (rr). Pine Tree (rr). Poor Farm (rr). Tenderfoot' 
 (rrr), Travis (r). 
 
 SCENEDESMUS OPOLiENSis P. Kichter. PI. 41 , Figs. 8 - 11 . 
 
 Zeits. f. angw. Mikr. 1: 7, figs. A-E. 1896. 
 
 Coenobia flat, of 2-4-8 (generally 4) cells in a single linear series. 
 Interior cells naviculoid, outer margin of terminal cells straight or 
 slightly convex. Cells in lateral contact in median third only. Termi- 
 nal cells with a long spine at each pole ; interior cells with or without 
 long or short spines. Polar spines greatly reduced at times. (Faculta- 
 tive Planktont). 
 
 Cells 5-8 p broad, 12-28 p long. 4-celled coenobia 12-28 p broad, 
 15-30 p long. Spines 5-28 p long. 
 
 Palmer (rr). 
 
 The navicular shape of the cells, their lateral contact in the median 
 third only, together with the beak-like instead of rounded apex sepa- 
 rates this species from S. quadricauda. 
 
160 
 
 WISCONSIN PHYTOPLANKTON 
 
 Sub-family C0ELA8TREAE. 
 
 Coenobia forming a sphere with the cells radially arranged in a single 
 layer around a common center. The number of cells in a coenoba al- 
 ways a multiple of two. Cells spherical, polygonal, or elongate cylindri- 
 cal. 
 
 KEY TO THE GENERA. 
 
 Cells spherical, polygonal, or flattened; length never more than twice the 
 
 breadth. 
 
 Cells without spines on the outer face Coelastrum 
 
 Cells with spines on outer face Sorastrum 
 
 Cells 3-7 times as long as broad Actinastrum 
 
 COELASTRUM Nageli 1849. 
 
 Coenobe a hollow sphere of 2-4-8-16-32-64-128 cells. Cells spheri- 
 cal, ovoid, or pyramidal ; compressed or with large intercellular spaces ; 
 enclosed in a very delicate gelatinous sheath. Daughter coenobia some- 
 times remaining joined in multiple coenobia by the remains of the old 
 mother cell wall. 
 
 Reproduction by autocolony formation in any cell of the coenobe. 
 Liberation of young coenobia by a rupture of old mother cell wall. 
 
 KEY TO THE SPECIES. 
 
 Cells spherical. 
 
 Processes uniting the cells long C. Reticulatxjm 
 
 Processes uniting the cells short. 
 
 External face of cells without projections C. Microporum 
 
 External face of cells with short truncate projections. . .C. Cambricum 
 Cells truncate cones ....C. Proboscideum 
 
 Coelastrum microporum Nageli. PI. 41, Figs. 12-13; PI. 42, Fig. 1. 
 in Braun, Alg. unicell. 70. 1855; Senn, Bot. Ztg. 57: 53, pi. 2, iigs. 11-17. 1899. 
 
 Coenobia spherical to ovoid ; with 8-16-32-64 cells. Cells spherical, 
 enclosed by a delicate gelatinous sheath and connected to one another 
 by short, stout, gelatinous processes. Intercellular interstices smaller 
 than the diameter of the cells. (Facultative Planktont). 
 
 Diam. cells (without sheath) 3-20 p,; (with sheath) 4-23 p,. Diam. 
 coenobia 20-90 p. 
 
 Balsam (rrr). Bear (1) (rr), Bear (2) (rr). Bear Trap (rrr), Big Butter- 
 nut (rrr), Blake (rrr). Bone (rrr), Boulder (rrr). Browns (rr). Center 
 (rr), Chetac (rr), Cochrane (rr). Deer (rrr). East (rrr), Elizabeth (rr), 
 Fishtrap (rrr), Granite (rr). Hill (rr), Hillman (rrr). Horseshoe (2) (rrr), 
 
WISCONSIN PHYTOPLANKTON 
 
 161 
 
 Island (rr), Lac du Flambeau (sss), Little Bass (2) (rr), Little Butternut 
 (rr), Little Crooked (rrr), Little Doctor (rr). Loveless (rrr), Lower Naah- 
 otah (rrr). Lower Turtle (rr), Mary (rr), Mendota (sss), Mill (rrr), Mud (2) 
 (rr), Nancy (rrr), Oconomowoo (rr). Otter (rrr), Pewaukee (rrr). Pine Tree 
 (rrr), Pokegama (1) (rr), Pokegama (2) (rr). Poor Farm (rrr). Pope (rrr), 
 Prairie (rrr). Round (1) (rrr). Sand (1) (rr). Sand (4) (rr). Shell (rrr). 
 Silver (1) (rr). South Turtle (rr). Squirrel (rr). Tenderfoot (rr). Tied Canoe 
 (rrr), Travis (rrr). Vermilion (rr), White Ash (rrr), White Sand (rrr). 
 Wolf (rrr). 
 
 A species that is found in all types of lakes. 
 
 CoELASTRUM CAMBRicuM Archer. PL 42, Figs. 2-3. 
 
 Quart. Jour. Micr. Sci. N. S. 8: 65. 1868; W. West, Jour, of Bot. 31: 99, pZ. 
 333, lig. 14. 1893. 
 
 Coenobia spherical, of 8-16-32-64r-128 (generally 32) cells. Cells 
 spherical, with a single truncate projection on the outer face. Each 
 cell connected to adjacent ones by short, somewhat flattened, gelatinous 
 projections. Small circular or triangular interstices between the cells. 
 ( Facultative Planktont ) . 
 
 Diam. cells (with sheath) 6-21 /a, (without sheath) 5-18 /a. Diam. 
 coenobia 20-100 /a. 
 
 Balsam (rrr). Bear (2) (rr), Beaverdam (rr), Birch Island (rrr). Blue 
 Gill (rrr). Catfish (rr), Cochrane (rrr). Cranberry (rr). East (rr). Found 
 (rr), Hillman (rrr), Jag (rr). Little Bass (2) (r), Mercer (rr). Middle Mc- 
 Kenzie (rrr), Minocqua (rr), Nancy (rrr), Nicaboyne (rr). Old Taylors (rrr), 
 Owen (rrr). Pine (1) (rr). Pine Tree (rr), Pokegama (1) (rr). Prairie (rr), 
 Rudolph (rrr), St. Croix (rr). Silver (1) (rr), Streitor (rr), Travis (r). 
 Wild Goose (rrr). 
 
 CoELASTRUM RECTicuLATUM (Dangcard) Senn. PI. 42, Figs. 4-6. 
 Bot. Ztg. 57: 66, pi. 2, figs. 1-10. 1899. 
 
 Coenobia spherical, of 8-16-32 cells ; generally held in multiple coe- 
 nobia by the remains of old mother cell walls. Cells spherical, enclosed 
 by a narrow gelatinous sheath and connected to adjacent cells by 6-9 
 long, slender, tough, gelatinous processes. (Facultative Planktont). 
 
 Diam. cells (with sheath) 6-24 fi. Diam. coenobia 10-65 /a. 
 
 Bear Trap (rrr). Bear (3) (rr), Beaverdam (rrr). Big McKenzie (rrr), 
 Birch (2) (rr), Blake (rrr). Browns (ss). Camp (rr). Fish (rr). High (rrr). 
 Island (rr). Lac Court Oreilles (rr). Little Bass (2) (rr), Mary (rr), Mendota 
 (rr). Mud (1) (rr), Mudhen (rr), Nancy (rr). North Twin (rrr). Palmer (rr). 
 
 The long processes connecting the cells distinguish this species from 
 all others. Solitary coenobia are rarely met with since the long proc- 
 esses hinder the escape of young coenobia. 
 
 11 
 
162 
 
 WISCONSIN PHYTOPLANKTON 
 
 CoELASTRUM PROBOSCiDEUM Bohlin. PI. 42, Figs. 7-8 ; PI. 43, Figs. 1-2. 
 Bih. t. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 33, pi. 2, figs. 19-22. 1897. 
 
 Coenobia pyramidal or cubical, rarely polygonal; of 4^8-16-32 (gen- 
 erally 4 or 8) cells; frequently joined in compound coenobia of irregu- 
 lar shape. Cells truncate cones, at times with concave sides ; with base 
 of cone towards the center of coenobe. Interstices between cells large, 
 polygonal. Chloroplast single, parietal, with one pyrenoid. (Faculta- 
 tive Planktont). 
 
 Diam. cells 6.5-17 /x; diam. 4-celled coenobia 12-35 /x; compound 
 coenobia up to 350 /x in diam. 
 
 Bear Trap (rrr), Cochrane (rr), Durchmans (rrr), Pine Tree (aa). Round 
 (rrr). 
 
 The appearance of this alga as the dominant organism of the plankton 
 of Pine Tree lake is of particular interest since Coelastrum species have 
 not been reported as occurring in abundance by any student of the 
 phytoplankton. Compound coenobia were very common and it was not 
 at all unusual to find 50-80 four- or eight-celled coenobia joined in one 
 irregular mass. The cells of four-celled coenobia are tetrahedrically 
 arranged in the manner that G. S. West has described them for Coelas- 
 irum compositum (Jour. Linn. Soc. Bot. 38: 136, pi. 5, figs. 8-9. 1907) 
 and I believe that G. compositum should be considered a synonym of 
 C. prohoscideum. The cellular arrangment of eight-celled coenobia is 
 exactly as Bohlin and Senn describe. In the sixteen-celled coenobia, 
 which are of very rare occurrence, the cells form a hollow sphere so that 
 the general appearance of the colony resembles the other species of the 
 genus. This difference in ceU number is of minor significance, the 
 number of cells in a colony being dependent upon the vegetative vigor 
 of the mother cell at the time colony formation takes place. 
 
 SORASTRUM Kutzing. 1845. 
 
 Cells pyriform, semilunar, or reniform; united to form spherical 
 colonies of 8-16-32-64-128 cells. Center of colony a polyhedral body 
 from which gelatinous strands radiate to each cell. Distal side of cells 
 with 1, 2, or 4 spines. Chloroplast diffuse, with one pyrenoid. 
 
 Reproduction unknown ; presumably by autocolonies as in Coelastrum^ 
 possibly by zoospores as in Pediastrum. 
 
WISCONSIN PHYTOPLANKTON 163 
 
 KEY TO THE SPECIES. 
 
 Spines on outer face of cells short (4-8 /*) S. SpiNuiiOSUM 
 
 Spines on outer face of cells long (10-15 /*) S. Amebicanum: 
 
 SoRASTRUM SPINULOSUM Nageli. PL 44, Figs. 4-5. 
 
 Gatt. einz. Algen 99, pi. 5, -figs. Da-Dd. 1849; G. S. West, Brit. Preshw. Algae 
 215, figs. 89A-89B. 1904. 
 
 Coenobe of 4-8-16-32 cells. Cells broadly renifonn to cuneate, with 
 four short horns at the corners of the outer face. Stipe leading to 
 sphere at center of colony short. Chloroplast single, generally filling 
 the entire cell; pyrenoid single. (Tychoplanktont). 
 
 Cells 8-20 {X broad, 6-18 ix long, 5-8 fx thick. Horns of adult cells 
 4-8 fx long. 
 
 Hillman (rrr), Horse (rrr). 
 
 SoRASTRUM AMERiCANUM (Bohlin) Schmidle. PI. 44, Fig. 1. 
 
 Engl. Jahrb. 27: 230. 1900: Lemmermann, Arch. f. Hydrob. u. Planktonkde. 
 5: 310, fig. 5. 1910. 
 
 Selenosphaerium americanum Bohlin, Bib. t. Kgl. Sv. Vet.-Ak. Handl. 23, 
 Afd. 3, No. 7: 40, pi. 2, figs. 38-41. 1897. 
 
 Coenobia spherical, solitary, of 16-32-64-128 (generally 16 or 32) 
 cells. Cells cardiate to pyramidate, somewhat flattened, with the apex 
 towards the center of the coenobe and ending in a broad gelatinous 
 stalk as long as the cell. Stalk cylindrical, 5-6 faceted at the base; 
 with the facets in contact with those of other stalks and forming a hol- 
 low sphere. Outer face of cells emarginate, with a single long spine at 
 each of the four corners. (Facultative Planktont). 
 
 Cells 7-20 fx broad, 5-20 fx long (without stalk), 4^S fx thick. Spines 
 of adult cells 10-15 fx long. 
 
 Devils (1) (rr), Devils (2) (rrr), Nancy (rrr), Travis (rr). 
 
 The longer spines and stalk, together with the more prominent central 
 sphere, separates this species from the foregoing. 
 
 var. UNDULATUM G. M. Smith. PI. 44, Figs. 2-3. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 640, pi. 13, fig- 7. 1918. 
 
 Sides of facets at base of stipe undulate. Dimensions as in the typi- 
 cal form. (Facultative Planktont). 
 
 Beaverdam (rrr). 
 
164 
 
 WISCONSIN PHYTOPLANKTON 
 
 ACTINASTRUM Lagerheim 1882. 
 
 Coenobia free-floating, of 4-8-16 (generally 8), ovoid, cylindrical, 
 club-shaped, or drum stick shaped cells radiating from a common cen- 
 ter. Coenobia sometimes united to form multii^’e coenobia of irregular 
 shape. Each cell with a single, laminate, parietal chloroplast; with 
 or without pyrenoids. 
 
 Reproduction by longitudinal and transverse division of the contents 
 of any cell, the young autocolony being liberated by a rupture of the 
 mother cell wall. 
 
 KEY TO THE SPECIES. 
 
 Center of cell twice as broad as poles A. Hantzsc?hi 
 
 Center of cells about the same width as the poles A. Graciulimum 
 
 Actinastrum GRAciLLiMUM G. M. Smith. PI. 43, Figs. 3-5. 
 
 Bull. Torr. Bot. Cl. 43: 480, pi. 26, fig. 23. 1916. 
 
 Coenobia of 4 or 8 cells radiating from a common center. Cells elon- 
 gate-cylindrical, tapering but slightly to a truncate end, 7-10 times as 
 long as broad. Chloroplast single, parietal, laminate, with or without 
 a pyrenoid. (Euplanktont). 
 
 Cells 1.75-3 fx broad, 14-21 long; colonies 30-45 fi in diam. 
 
 Horse (rr), Kegonsa (rrr), Mendota (rr). 
 
 The species differs from the following in the very slight dilation of 
 the median portion of the cell and the greater proportional length. 
 
 Actinastrum Hantzschi Lagerheim. PI. 43, Figs. 6-7. 
 
 Ofvers. Kgl. Vet.-Ak. Porh. 39, No. 2: 70, pi. 3, figs. 25-26. 1882. 
 
 Coenobia of 4 or 8 cells radiating from a common center. Coenobia 
 sometimes united to form multiple coenobia. Cells 3-6 times as long 
 as broad, with truncate poles, ovoid-cylindrical. Diameter of middle 
 of cells twice that of poles. Chloroplast single, parietal, laminate ; with 
 one pyrenoid. (Euplanktont). 
 
 Cells 3-6 fi broad, 10-26 fx long ; coenobia up to 50 fx in diam ; com- 
 pound coenobia up to 200 fx in diam. 
 
 Chetek (rr), Kegonsa (r). Lower Turtle (rrr), Mendota (rr), Prairie (rr). 
 Upper Turtle (rr), Waubesa (rrr). 
 
 Multiple coenobia are of rare occurrence and have only been found 
 in the plankton of Chetek lake. This may be due to the fact that such 
 colonies readily fragment into the individual coenobia and the handling 
 incident to the collection of samples is sufficient to break up multiple 
 coenobia. 
 
WISCONSIN PHYTOPLANKTON 
 
 165 
 
 var. ELONGATUM G. M. Smith. PI. 43, Fig. 8. 
 
 Trans. Wis. Acad. Sci., Arts, & Liett. 19^: 636, pi. 12, -fig. 3. 1918. 
 
 Colonies of 4 or 8 cells. Cells cylindrical, tapering but little towards 
 the poles. ( Euplanktont) . 
 
 Cells 4^5 II broad, 30-35 long. 
 
 Bear (3) (rr). 
 
 The cells of this variety are much longer than those of the typical 
 form. 
 
 Family HYDRODICTYACEAE. 
 
 Cells cylindrical, or flattened and hexagonal to trapezoidal with one, 
 two, or four projections. Coenobia of definite shape; cylindrical with 
 a large number of cells; or disciform with 2-4-8-16-32-64-128 cells. 
 Cells incapable of division after their formation. Chloroplast single, 
 parietal, laminate to reticulate, frequently filling the entire mature 
 cell ; with one to many pyrenoids. 
 
 Asexual reproduction by the divisioli of contents of any cell to form 
 zoospores that swarm within old cell wall or within a gelatinous vesicle 
 extruded from the cell. Zoospores becoming apposed in the shape of 
 the adult cell when they come to rest. 
 
 Sexual reproduction by isogamous zoogametes which fuse in pairs to 
 form angular resting cells which form colonies on their germination. 
 
 KEY TO THE GENERA. 
 
 Coenobe a hollow cylindrical tube with rounded ends Hydeodictyon 
 
 Coenobe a flattened disc one cell in thickness. 
 
 Number of cells in coenobe always 2 Etjasteopsis 
 
 Number of cells in coenobe 4-8-16-32-64-128, very 
 
 rarely 2 Pediastbum 
 
 HYDRODICTYON Roth 1800. 
 
 Cells macroscopic, oblong-cylindrical with rounded ends; united to 
 form a free-floating, reticulate, saccate coenobium. Meshes of nets 
 3-12 (generally 5-6) sided. Cells coenoeytic; chloroplast parietal, 
 reticulate at first, later diffuse; pyrenoids single in very young cells, 
 several hundred in mature cells. 
 
 Asexual reproduction by the division of cell contents into very many 
 biciliate zoospores which swarm about in and become arranged as in 
 the mature coenobe within the old mother cell wall. Liberation of the 
 young coenobe by a gradual gelatinization of the mother cell wall. 
 
 Sexual reproduction by zoogametes which are similar in structure to 
 
166 
 
 WISCONSIN PHYTOPLANKTON 
 
 zoospores but smaller, the zoogametes fusing in pairs to form a spheri- 
 cal zygote after their liberation through a pore in the cell wall. Zygote 
 germinating, after a short period of rest, into 2-5 large uni- or biciliate 
 zoospores that form irregular polyhedral cells on coming to rest. Poly- 
 eders ultimately germinating into 200-300 zoospores that are liberated 
 in a vesicle and form a net as in asexual reproduction. 
 
 Hydrodictyon reticulatum (L) Lagerheim. PI. 44, Fig. 6; PI. 45, 
 
 Fig. 1 . 
 
 dfvers. Kgl. Vet.-Ak. Forh. 40, No. 2: 71. 1883; G. S. West, Brit. Freshw. Algae 
 208, figs. 84A-84F. 1904 
 
 Cells elongate cylindrical, forming a definite closed net. (Tycho- 
 pJanktont) . 
 
 Cells 5-250 ii broad, up to 1.5 cm. long. Coenobia up to 30 cm. long. 
 Little Bass (2) (rr), Mendota (rr), Monona (sss). 
 
 An alga that is in no sense a plankton organism but one which some- 
 times grows in abundance in shallow, well protected bays and so may, 
 at times, be found free-floating in large patches a considerable distance 
 from the shore. 
 
 PEDIASTKUM Meyen 1829. 
 
 Coenobia disciform to stellate, free-floating, of 2-4-8-16-32-64-128 
 cells arranged in a layer one cell in thickness. Coenobe entire, perfor- 
 ate, or clathrate. Marginal cells polygonal, with one, two, or four proc- 
 esses that sometimes terminate in a tuft of long hyaline setae. Interior 
 cells polygonal, without processes. Cell wall smooth, granulate, or 
 covered with a meshwork of fine ridges; without a gelatinous sheath. 
 Chloroplasts parietal and disciform at first, later filling the entire cell ; 
 with 1-4 pyrenoids. Cells coenoc 5 d;ic. 
 
 Asexual reproduction by the division of contents of any cell into 
 2-4-8-16-32-64-128 biciliate zoospores that are extruded in a gelatinous 
 vesicle and, after a short period of swarming, on becoming quiescent 
 appose themselves in the same position as the mature cells of the 
 coenobe. 
 
 A fusion of biciliate zoogametes into polyhedral resting cells has been 
 observed. On germination these zygospores form 8-16-32 zoospores 
 that behave as in asexual reproduction. 
 
WISCONSIN PHYTOPLANKTON 
 
 167 
 
 KEY TO THE SPECIES. 
 
 Outer face of marginal cells without projections. 
 
 W all smooth p. Integrum 
 
 Wall reticulate P. Araneosum 
 
 Outer face of marginal cells with 1, 2, or 4 projections. 
 
 Marginal cells with more than one projection. 
 
 Cells on margin with four projections and a deep linear incision. .P. Tetras 
 
 Cells on margin with two projections. 
 
 Coenobe entire. 
 
 Cell wall smooth or punctate. 
 
 Projections side by side in front view of cell P. Boryanum 
 
 Projections above one another in front view P. Kawraiskyi 
 
 Cell wall reticulate. 
 
 Wall covered with coarse reticulations P. Araneosum 
 
 Wall covered with fine reticulations P. Sculptatum 
 
 Coenobe perforate. 
 
 Ends of projections truncate P. Duplex 
 
 Ends of projections incised P. Biradiatum 
 
 Marginal cells with one projection P. Simplex 
 
 Pediastrum simplex var. duodenarium (Bailey) Rabenhorst. PL 45, 
 
 Figs. 2-6. 
 
 Fl. Eur. Algarum 3: 72. 1868. 
 
 Monactinns duodenarius Bailey, Smithsonian cont. to knowl. 7, Art. 3: 14, 
 pi. 1, fig. 37. 1855. 
 
 Monactinus octonarius Bailey, iMd. p. 14, pi. 1, fig. 36. 1855. 
 
 Pediastrum simplex var. clatfiratum (Schroter) G. S. West, Jour. Linn. Soc. 
 Bot. 38: 134. 1907. 
 
 Coenobia circular to oval, of 4-8-16-32-64-128 (generally 8-16-32) 
 cells. Inner face of marginal cells concave, outer face produced into 
 a single, delicately tapering, concave process frequently furnished with 
 a tuft of delicate hyaline setae. Interior cells as those of the periphery 
 but with shorter processes. Interstices between cells large. Cell wall 
 smooth or finely punctate. (Facultative Planktont). 
 
 Cells 10-24 fl broad, 20-45 fi long. 
 
 Balsam (rr). Bear (1) (r). Bear Trap (rrr), Blake (r), Camp (rr). Green 
 (1) (rrr). High (rr), Hillman (rrr), Kegonsa (rr). Little Bass (rr), Little 
 Butternut (r). Little Crooked (rrr), Lost (rr). Loveless (rrr), Mary (rr), 
 Monona (r). Mud (2) (rr). Palmer (rrr), Pokegama (1) (sss). Rice (1) (r), 
 St. Croix (rr), Silver (1) (rr). Spirit (rr). Upper Turtle (r). Vermilion (cc), 
 Wapagossett (r). White Ash (rr), Winnebago (rr). Wolf (rrr). 
 
 This alga is one that has been given a number of names by various in- 
 vestigators, but for the reasons stated elsewhere (Trans. Wis. Acad. Sci., 
 Arts, & Lett. 19^: 642. 1918) I consider the one given above the proper . 
 
 name. 
 
168 
 
 WISCONSIN PHYTOPLANKTON 
 
 Pediastrum integrum Nageli, PI. 45, Fig. 7. 
 
 Gatt. einz. Algen 97, p?. 5, figs. B4a^B4r. 1849. 
 
 Coenobia 8-16-32-64-celled, circular or oval, without perforations. 
 Interior cells polygonal; marginal cells 5-6 sided, at times with rudi- 
 ments of two projections that are sometimes reduced to a single wart, 
 but generally without projections. Cell wall smooth or punctate. 
 
 ( Tychoplanktont) . 
 
 Diam. cells 15-30 /x. 
 
 Soft (rrr). 
 
 var. PRiVA Printz. PI. 45, Pigs. &-10. 
 
 Skr. Vidensk. i Kristiana Mat.-Naturv. Kl. 1913': No. 6: 73, pi. 5, fig. 147. 
 1914. 
 
 Coenobia generally 8-celled. Marginal cells trapezoidal, without in- 
 cisions or processes. Interior cells polygonal, without incisions. Cell 
 wall smooth. (Facultative Planktont). 
 
 Diam. cells 8-10 /x. Diam. 8-celled coenobia 15-25 /x. 
 
 Palmer (rr). 
 
 The general shape of the cells is like that of P. tetras but since there 
 are no incisions in the cells they cannot be placed among the varieties 
 of P. tetras. 
 
 Pediastrum araneosum Raciborski. PI. 45, Fig. 11. 
 
 Mem. Acad. Imp. Sci. Cracow 20: 84. 1890. 
 
 Coenobia circular to oval, without perforations, of 8-16-32-64-128 
 cells. Interior cells in contact with 4^6 other cells, straight sided. In- 
 ner half of marginal cells similar to interior cells, outer half without 
 processes but with a deep emargination. Surface of cell covered with 
 a coarse reticulum of ridges. (Facultative Planktont). 
 
 Diam. cells 15-32 /x. 
 
 Birch Island (rr), Blue Gill (rrr), Boulder (rrr), Carson (rrr). Deer (rrr). 
 Devils (1) (rrr), Diamond (rrr), Dutchmans (rr). Horseshoe (1) (rr). Lake 
 of the Woods (rrr), Lindy (rr). Loon (rrr), Nicahoyne (rr), Nancy (r). Pine 
 Tree (rr), Pokegama (1) (rrr). Poor Farm (rrr). Sand (2) (rr), Wild 
 Goose (rr). 
 
 var. RUGULOSUM (G. S. West) G. M. Smith. PI. 45, Figs. 12-13. 
 Bull. Torr. Bot. Cl. 43: 476, pi. 25, fig. 14. 1916. 
 
 Sides of cells undulate where they are in contact with one another. 
 (Facultative Planktont). 
 
 Meta (r). 
 
WISCONSIN PHYTOPLANKTON 
 
 169 
 
 Pediastrum sculptatum G. M. Smith. PI. 46, Fig. 1 . 
 
 Bull. Torr. Bot. Cl. 43: 475, pL 25, fig. 13. 1916. 
 
 Coenobia oval to circular, of 8-16-32 cells. Interior cells with 4-6 
 straight sides, with a few interstices between the cells. Marginal cells 
 bilobed, with the lobes produced into two short divergent or parallel 
 processes. Cell wall covered with a network of very fine ridges. (Fac- 
 ultative Planktont) . 
 
 Diam. cells 10-15 ju,. Diam. coenobia 80-150 /x. 
 
 South Turtle (rr). 
 
 Pediastrum Boryanum (Turpin) Meneghini. PI. 46, Figs. 2-7. 
 
 Linnaea 14: 210. 1840; G. S. West, Brit. Freshw. Algae 211, figs. 85 f- 85 h. 
 1904. 
 
 Coenobia circular to ovoid, of 4^8-16-32-64^-128-256 (generally 8- 
 16-32) cells that are normally compactly arranged in concentric rings. 
 Interior cells 4-6 sided, with straight sides. Inner half of marginal 
 cells similar to interior cells ; outer half produced into two short obtuse 
 processes ending in short spines, slightly to deeply emarginate between 
 the processes. Projections on outer face and their spines sometimes 
 greatly reduced. Wall smooth or granulate. (Facultative Planktont). 
 
 Diam. cells 7.5-30 /x. Diam. 16-celled coenobia 40-100 (i. 
 
 Balsam (rrr). Bear (1) (rrr), Bear (2) (rrr). Bear (3) (ss). Bear Trap 
 (rr), Beasley (rr), Beaver (rr), Beaverdam (ss). Big Butternut (rr), Birch 
 Island (rr), Blake (rr). Bloom (r), Boulder (rrr), Browns (rr). Camp (r), 
 Carroll (sss), Carson (rrr), Catherine (rr). Center (ss), Chetac (rr), Chetek 
 (rrr). Clear Crooked (rr), Cochrane (rrr). Crawling Stone (rr). Deer (r), Des 
 Moines (rr). Devils (1) (rr). Eagle (sss). East (rrr), Elizabeth (rrr). Fence 
 (rrr), Fishtrap (rr). Found (rr), Fowler (rrr), Geneva (rr), Granite (rr), 
 Grassy (rr). Green (2) (rrr). Grindstone (rr). Half Moon (rrr), Harris (rr). 
 High (rr), Hillman (rr). Hooker (rr). Horse (rrr). Horseshoe (1) (ss), 
 Kawaguesaga (r), Kegonsa (sss). Kitten (rr). Lac la Belle (rr). Lac Court 
 Oreilles (rr). Lac du Flambeau (r), Lindy (rr). Little Bass (2) (r). Little 
 Bear (sss). Little Butternut (rrr). Little Crooked (rr). Little Rice (2) (rr). 
 Little Wood (rrr). Long (2) (rr). Long (3) (rrr). Loveless (r). Lower Nash- 
 otah (rrr). Lower Nemahbin (rr). Lower Turtle (rr). Marl (rr), Mary (ss), 
 Mendota (ss), Monona (ss). Mud (1) (r). Mud (2) (r), Mudhen (rr), Muskal- 
 loDge (rr), Nagawicka (rr), Nancy (sss), Nicaboyne (rrr), Oconomowoc (rr). 
 Old Taylors (rr), Owen (r). Paddock (rrr), Pewaukee (rr). Pine (2) (rrr), 
 Pokegama (1) (sss), Pokegama (2) (r), Pokegama (3) (rr). Poor Farm (rr). 
 Poplar (rr). Prairie (rrr). Rainbow (rr). Reserve (rrr), Rice (1) (rr). Round 
 (1) (sss). Round (2) (rr), St. Croix (rr). Sand (1) (rrr). Sand (3) (rrr), 
 Sand (4) (sss). Silver (2) (r), Spirit (rr). Star (rr), Streitor (rr), Taylor 
 (r). Tenderfoot (rrr). Tied Canoe (rrr). Turtle [North and South] (rr), Up- 
 
170 
 
 WISCONSIN PHYTOPLANKTON 
 
 per Turtle (r), Vermilion (rr), Waubesa (r), White Ash (sss), Whitefish (rr), 
 White Sand (rr). Wildcat (rrr), Winnebago (r), Wolf (s). 
 
 A species that is almost universally present and one which varies 
 greatly in the character of the marginal cells. 
 
 var. UNDULATUM Wille. PI. 46, Fig. 8. 
 
 Ofvers. Kgl. Vet.-Ak. Forh. 36, No. 5: 28. 187'9. 
 
 Sides of cells in contact with other cells undulate instead of straight. 
 ( Tychoplanktont) . 
 
 Winnebago (rr). 
 
 var. LONGICORNE Kaciborski. PI. 46, Fig. 9. 
 
 Akad. Umiej. w. Krakowie 20: 13. 1889; Printz, Skr. Vidensk. i Kristiana 
 Mat.-Natury. Kl. 1913, No. 6: 74, pi, 5, fig^ 149. 1914. 
 
 Horns at the ends of processes much longer than typical form, some- 
 times swollen at apex. Cell wall smooth or granulate. 
 
 Diam. cells up to 40 fx. Horns 12-30 [x long. 
 
 Bone (rrr). 
 
 Raciborski recognizes the forms glabrum and granviatum but, judg- 
 ing by the variation in the nature of the wall in the typical form, these 
 forms should not be recognized. 
 
 Pediastrum Kawraiskyi Schmidle. PI. 46, Figs. 10-13. 
 
 Arb. d. Botan. Gartens zu Tiflis 2: 269. 1897; Nitardy, Beih. z. Bot. Cent. 32-: 
 164, pi. 5, fig. 6. 1914. 
 
 Coenobia of 16-32-64 cells that are compactly arranged. Interior 
 cells 4—6 sided, sides straight. Inner half of marginal cells as interior 
 cells, outer half with two short projections that lie one above the other 
 when the coenobe is seen in surface view. Cell wall smooth. (Eu- 
 pJanktont). 
 
 Diam. cells 9-22 fx. Diam. 32-celled coenobia 60-100 /a. 
 
 Big Bass (r). Palmer (rr). Tenderfoot (rrr), Winnebago (r). 
 
 The cell shape is quite similar to P. Boryanum but the peculiar posi- 
 tion of the processes on the marginal cells at once distinguishes this 
 species from all others. Some investigators are inclined to the view 
 that P. Kawraiskyi is but a passing condition of P. Boryanum that is 
 found for one generation only. I have grown P. Boryanum in pure 
 cultures for several years and have never seen a single coenobe with the 
 projections of marginal cells lying one above the other, and so feel con- 
 fident that P. Kawraiskyi is not a temporary growth condition of 
 P. Boryanum. 
 
WISCONSIN PHYTOPLANKTON 
 
 171 
 
 Pediastrum duplex Meyen. PL 46, Figs. 14-16. 
 
 Nova Acta Phys. Med. Ac. Caes. Leop.-Carol. Nat. Cur. 14^• 772, pi. 43, figs. 
 6-20. 1829. 
 
 Coenobia of 8-16-32-61r-128 (generally 16-32) cells, with small lens- 
 shaped perforations between the cells. Interior cells more or less rec- 
 tangular, not in contact with one another in the central portion of the 
 side walls. Inner half of marginal cells similar to interior cells, outer 
 half prolonged into two short truncate processes. Cell wall smooth. 
 (Facultative Planktont). 
 
 Diam. cells 11-21 /a. 
 
 Balsam (rrr). Bear (2) (r), Birch Island (rr), Browns (rr), Catherine (rr). 
 Center (r). Clam (rrr), Cochrane (rr). Crawling Stone (r). Deer (rr), Des 
 Moines (rrr), Diamond (rrr). Eagle (r), Fishtrap (rr). Found (rr), Fowler 
 (rr), Helen (1) (rr). High (rr), Kawaguesaga (rr), Kegonsa (r). Kitten (r). 
 Lac la Belle (r), Lindy (rr). Little Bass (2) (rr), Little Bear (r). Little 
 Crooked (r). Little Rice (2) (rr). Long (3) (rrr). Lost (rr), Mendota (sss), 
 Mercer (rr), Meronk (rrr), Monona (c), Nagawicka (rr), Nancy (sss), Nica- 
 boyne (rrr). North Twin (rr), Oconomowoc (rr), Okauchee (rr), Pardee (rr), 
 Pokegama (1) (ss), Pokegama (2) (rr). Poor Farm (r). Poplar (rrr). Round 
 (1) (r). Round (2) (rr). Sand (4) (sss), Sishebogema (rr). Soft (r). South 
 Turtle (sss), Taylor (rr). Tenderfoot (r). Tied Canoe (rrr). Upper Nemahbin 
 (rr), Waubesa (ccc), White Sand (rrr). Wildcat (sss). Wild Goose (rrr), 
 Winnebago (ss),Wolf (sss). 
 
 In many cases the marginal cells of this species and the varieties 
 clathratum, reticulatum and graeilUmum have a tuft of long hyaline 
 setae at the apex of the projections. Their function is to give buoyancy 
 to the coenobe when living under pelagic conditions. Petersen (Bot. 
 Tids. 31: 161-176. 1911) has been able to demonstrate their presence 
 in other species by means of stains. 
 
 var. CLATHRATUM (A. Braun) Lagerheim. PL 47, Pigs. 1-3. 
 Ofvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 56. 1882. 
 
 Cells more deeply emarginate and perforations of disc larger. (Fac- 
 ultative Planktont). 
 
 Diam. cells 12-22 ft. 
 
 Balsam (rr), Bear (3) (rr). Bear Trap (rr), Beaverdam (sss). Big Butter- 
 nut (rr), Blake (r). Bloom (rr). Camp (ss). Catfish (rr), Catherine (rr), 
 Chetek (s). Cranberry (rr). East (rrr). Fish (s). Horseshoe (1) (rr). Horse- 
 shoe (2) (rr). Lac du Flambeau (rrr). Lac la Belle (r). Little Bass (2) (sa). 
 Little Butternut (r). Little Wood (rrr). Long (1) (rrr), Loveless (sss). 
 Lower Turtle (r), Mary (r), Mendota (r). Middle McKenzie (s). Mud (2) (rr), 
 Mud (3) (sss), Nancy (r), Okauchee (rrr). Old Taylors (rrr), Pokegama (1) 
 (r). Rice (1) (ss). Round (2) (rr), Sand (3) (rr). Sand (4) (r). Spirit (sss). 
 Upper Turtle (sss), Wapagossett (rr). White Ash (r). 
 
172 
 
 WISCONSIN PHYTOPLANKTON 
 
 var. RETicuLATUM Lagerheim. PI. 47, Figs. 4-7. 
 ofvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 56, pi. 2, fig. 1. 1882. 
 
 Perforations of coenobe very large, oval. Interior cells sub-cruciate 
 to H-shaped. Sides of projections of marginal cells parallel, projec- 
 tions generally terminating in a tuft of delicate long hyaline setae. 
 (Euplanktont ?). 
 
 Cells 10-20 fi broad, 15-40 fi long. 
 
 Big (rr), Camp (s), Center (s), Clietek (b), Crab (rr), Hill (rr), Hooker 
 (rr), Horse (sss), Island (sss), Kawaguesaga (rr), Little Bear (rr). Little 
 Rice (1) (rr). Lost Bass (r), Loveless (r), Nancy (r), Paddock (rr), Palmer 
 (r), Pardee (r). Pine (2) (rrr), Pokegama (1) (r), Pokegama (3) (ss), 
 Prairie (ss). Reserve (rr). Rice (r), St. Croix (sss), Sisbebogema (r). South 
 Turtle (rr), Tenderfoot (rr), Waubesa (rr), Whitefish (rr), Winnebago (rr). 
 
 var. GRACiLLiMUM W. & G. S. West. PI. 47, Figs. 8-11 ; PI. 48, Figs. 1-2. 
 Jour, of Bot. 33: 52. 1895. 
 
 Cells very narrow, never wider than the processes. Body of margi- 
 nal cells curved outwards, with two long, somewhat converging processes 
 that have parallel or slightly convex sides. Interior cells like those of 
 margin but with somewhat shorter processes. Perforations of coenobe 
 very large. (Euplanktont). 
 
 Cells 10-22 fjL broad, 12-32 /a long. Diam. 16-celled coenobia 65-140 /x. 
 
 Clam (rr). Pine Tree (sss), Travis (r). 
 
 The perforations of the coenobe and the extension of the processes 
 are the greatest in this variety. The varieties clathratum, reticvlatum, 
 and gracillimum are not sharply defined and it is possible, taking the 
 collections as a whole, to arrange a series that grades almost impercept- 
 ibly from the typical form to the variety gracillimum. The individuals 
 from any one lake, however, generally vary within fairly narrow limits 
 so I feel that these varieties should be recognized instead of putting 
 them in one collective species without varieties. 
 
 var. ROTUNDATUM Lucks. PI. 46, Fig. 17. 
 
 Jahrb. d. Westpr. Lehrervereins f. Naturk. 2-3: 31. 1907; Nitardy, Beih. z. 
 Bot. Cent. 32=*: pi. 9, fig. 11. 1914. 
 
 Projections of marginal cells markedly convex and capitate instead 
 of parallel. (Tychoplanktont). 
 
 Oconomowoc (rrr). Horseshoe (1) (rr). 
 
WISCONSIN PHYTOPLANKTON 
 
 173 
 
 var. coHAERENS Bohlin. PI. 48, Figs. 3-4. 
 
 Bih. t. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 31, pZ. 2, fig, 1. 1897. 
 
 Pediastrum duplex var. reticulatum forma coJiaerens (Bohlin) Brunnthaler, 
 in Pascher, D. Siisswasserfl. Deutschl., osterr. u. d. Schw. 5^: 95, fig. 57e. 1915. 
 
 Coenobia circular to oval, of 16-32-64 cells, with median-sized inter- 
 cellular spaces. Wall of cells covered with short, linear, concentrically 
 arranged granules. (Facultative Planktont). 
 
 Cells 12-22 fjL broad ; 13-24 fi long. 
 
 Pine Tree (r). 
 
 Pediastrum biradiatum Meyen. PI. 48, Figs. 5-8. 
 
 Nova Acta Phys.-Med. Ac. Caes.-Leop. Nat. Cur. 14^: 773, pi. 43, figs. 21-22. 1829. 
 
 Pediastrum rotula (Ehrenberg) A. Braun emend. Alg. unicell. 101, pi. 6, 
 figs. 2-3, 5-7, 10, 12-14. 1855. 
 
 Coenobia of 4-8-16-32-64 cells, with medium sized openings between 
 cells. Marginal cells in contact with one another at base only, with 
 two long projections that are dilate and incised at the apex. Interior 
 cells as those of the margin but apices of projections neither dilate nor 
 incised, in contact with other cells at base and ends of projections only. 
 Cell wall smooth. (Facultative Planktont). 
 
 Cells 10-22 broad, 15-30 fi long. Diam. 32-celled coenobia 80-150 /x. 
 
 Balsam (rrr). Bear (3) (rr), Big McKenzie (rr), Lac du Flambeau (rr), 
 Mud (2) (rr), Nancy (rrr), Pokegama (1) (rrr), Wolf (rrr). 
 
 This species resembles P. duplex var. reticulatum in the perforation 
 of the disc but differs in the deep incision of the marginal cell projec- 
 tions. Perfect colonies are seldom seen since apices of projections of 
 certain interior cells are free and have the same dilation and incision 
 that is found in the marginal cells. The number of ceUs in the colony 
 is generally stated as 8-16-32 but the coenobia in the plankton of Wis- 
 consin lakes are 32- or 64-celled except in very rare cases. 
 
 Pediastrum tetras (Ehrenberg) Ralfs. PL 48, Figs. 9-12. 
 
 Ann. & Mag. of Nat. Hist. 14: 469, pi. 12, fig. 4. 1844. 
 
 Coenobia rectangular, oval or circular; without perforations; of 
 4-8-16-32 (generally 4-8) cells. Outer face of marginal cells with a 
 single deep linear to cuneate incision, the halves of the outer face 
 slightly to deeply emarginate. Interior cells with a single deep linear 
 incision and 4-6 straight sides. Cell wall smooth. (Tychoplanktont). 
 
 Diam. cells 8-15 /x. 
 
 Blake (rrr). Browns (rrr). Chain (rrr), Chetek (rr), Cochrane (rrr), Hill- 
 man (rrr). Horse (rrr). Horseshoe (2) (rrr), Kimball (rrr), Lindy (rrr). 
 
174 
 
 WISCONSIN PHYTOPLANKTON 
 
 Little Doctor (rr), Mendota (rrr), Palmer (rrr), Pewaukee (rrr), Pine (2) 
 (rr), Pokegama (1) (rr), Poor Farm (rr), Tied Canoe (rrr). 
 
 The four projections in the outer face of marginal cells are due to a 
 deep emargination of the two halves. This, coupled with the deep in- 
 cision of all cells, at once separates the species from others of the genus. 
 The alga does not thrive under plankton conditions although it is com- 
 mon in ditches and ponds of the state. 
 
 var. OBTUSATA Raciborski. 
 
 Akad. Umiej. w. Krakowie 20: 32. 1889; Printz, Skr. Vidensk. i Kristiana 
 Mat.-Naturv. Kl. 1913S No. 6: 78, pi. 6, fig. 153. 1914. 
 
 Cells larger than typical form, sometimes expanded at base. Halves 
 of outer face of marginal cells entire or very slightly emarginate. 
 ( Tychoplanktont ) . 
 
 Diam. cells 14-18 p , ; length 18-22 p.. 
 
 Beaverdam (rrr). 
 
 var. TETRAODON (Corda) Hansgirg. PI. 48, Figs. 13-14; PI. 49, Figs. 1-2. 
 
 Prodr. d. Algenfl. v. Bohmen 1: 112. 1888. 
 
 Euastrum tetraodon Corda, Almanach de Carlsbad 9: 238, pi. 2, fig. 9. 1839. 
 
 Coenobia generally 8-celled. Incision of cells deep, and with projec- 
 tions adjacent to incision very pronounced on marginal cells. (Facul- 
 tative Planktont). 
 
 Diam. marginal cells 8-15 ju,; length 12-18 fi. 
 
 Pine Tree (rr), Travis (r). 
 
 There is no question that my figures of the organism are identical 
 with the one that Nitardy (Beih. Bot. Cent. 32^ : 123, pi. 5, fig. 8. 1914) 
 has reproduced from Corda. The variety is sharply defined through 
 the greater development of the projections. 
 
 EUASTROPSIS Lagerheim 1894. 
 
 Coenobia free-floating, 2-celled. Cells flattened, approximated at the 
 bases, distal end free and deeply emarginate. Chloroplast single, pari- 
 etal, with one pyrenoid. 
 
 Asexual reproduction by division of cell contents into 2-4^8-16-32 
 zoospores which are extruded in a vesicle and on becoming quiescent 
 join in pairs to form the characteristic coenobe. 
 
 Sexual reproduction unknown. 
 
WISCONSIN PHYTOPLANKTON 
 
 175 
 
 Euastropsis Richteri (Schmidle) Lagerheim. PI. 49, Fig. 3. 
 Tromso Museums Aarshefter 17 : 20, pi. 1, figs. 8-27. 1894. 
 
 Cells trapezoidal, outer face deeply emarginate. (Tychoplanktont). 
 
 Cells 4.5-25 /a broad, 5-20 /x long. Coenobia 4.5-25 fi broad, 10-40 
 (I long. 
 
 Kegonsa (rrr). 
 
 It is quite possible to mistake 2-celled Pediastrum colonies for 
 E. Richteri, but since such Pediastrum colonies are of very rare occur- 
 rence the similarity of the two is not apt to lead to confusion. ' 
 
 Family PLAN 08P0R ACE AE. 
 
 Cells solitary or gregarious; ovoid, pyriform, fusiform, cylindrical, 
 or hemispherical ; epiphytic, endophytic, or epizootic. Cells capable of 
 growth but incapable of division after their formation. Generally with 
 a single chloroplast with one or more pyrenoids. 
 
 Asexual reproduction by division of cell contents to form many zoo- 
 spores. 
 
 Only one genus, Characium, is found in the plankton of the state. 
 
 CHARACIUM A. Braun 1849. 
 
 Cells sub-spherical, ovoid, pyriform, fusiform, or cylindrical; soli- 
 tary or gregarious; epiphytic or epizootic; generally attached to sub- 
 stratum by a more or less elongate stipe, rarely sub-sessile. Chloroplast 
 parietal and laminate to cup-shaped in young cells ; later expanded to 
 fill entire cell : with one or more pyrenoids. Cells at times with several 
 chloroplasts. 
 
 Asexual reproduction by repeated division of cell contents into 8-16- 
 32-64-128 zoospores that are liberated through a lateral or apical pore. 
 Zoospores swarming but a short time and then coming to rest on sub- 
 stratum and developing into vegetative cells. 
 
 Microgametes reported but doubtful. 
 
 KEY TO THE SPECIES. 
 
 Epiphytic upon other algae. 
 
 Cells ovoid C. Stipitattjm 
 
 Cells lunate C. Cubvatum 
 
 Epizootic upon crustaceans. 
 
 Apices of cells rounded C. Cylindbictjm 
 
 Apices of cells produced into a fine seta. 
 
 Stipe simple C. Limnetictjm 
 
 Stipe ending in filiform rhizoids C. Geachjpes 
 
176 
 
 WISCONSIN PHYTOPLANKTON 
 
 Characium stipitatum (Bachmann) Wille. PL 49, Figs. 4-7. 
 
 in Engler & Prantl, Nat. Pflanzenfam. V (Nachtr.); 45. 1909; G. M. Smith, 
 Bull. Torr. Bot. Cl. 43: 472, pi, 24, figs. 4-6. 1916. 
 
 Cells spherical to pyriform, with a delicate hyaline stipe somewhat 
 longer than the cell. Chloroplast single, parietal, cup-shaped, always 
 on the side away from the stipe; pyrenoid single. Zoospores broadly 
 ovoid, biciliate, with a cup-shaped chloroplast at the posterior end. 
 (Euplanktont). 
 
 Epiphytic upon and embedded within the gelatinous envelope of 
 Coelosphaerium Naegelianwn Unger. 
 
 Cells 5-8 fx broad. Stipe 10-16 p. long. 
 
 Amicoy (r). Balsam (rr), Beartrap (rr), Beaverdam (s), Big (rr), Big 
 McKenzie (ss), Clam (ss), Devils (2) (ss). Horseshoe (1) (ss), Horseshoe 
 (2) (rr), Long (2) (ss), Kawaguesaga (ss). North Twin (sss), Pardee (r). 
 Pike (rr), Pokegama (1) (s), Pokegama (2) (r). Poplar (rrr), St. Croix (r). 
 Sand (4) (rr), Sishebogema (rr). 
 
 In one case the alga was found upon Oocystis but in all others it was 
 inside the gelatinous envelope of Coelosphaerium Naegelianwn Unger. 
 When the alga grows upon Coelosphaerium the colony is apt to be in- 
 fested with 50-100 individuals as a rule. The alga was originally des- 
 cribed as a Chlamydomonas species but since the sessile phase is the 
 dominant one of the life cycle it is better placed as a Characium species. 
 Although found at only one station in Europe it is widely distributed 
 in northern Wisconsin. 
 
 Characium curvatum G. M. Smith. PI. 49, Figs. 8-15. 
 
 Trans. Wis. Acad. Sci., Arts, & Lett. 19^: 641, pi. 11, figs. 6-13. 1918. 
 
 Cells lunate or recurved, with acute or sub-acute apices. Stipe hya- 
 line, thick, tubular or conical, sometimes irregular in outline. Chloro- 
 ])last single, parietal, laminate to cup-shaped; with or without a pyre- 
 noid. ( Euplanktont) . 
 
 Epiphytic upon Coelosphaerium Naegelianum Unger, Bictyosphaer- 
 ium pulchellum Wood, and Phaeococcus planet onicus W. & G. S. West. 
 
 Cells 3-6 /A broad, 8-18 p long (without stipe), 13-22 /a long with 
 stipe. 
 
 Bear (1) (rr), Birch (2) (cc). Chain (rr), Chetac (aa), Chetek (rr), Clam 
 (sss). East (rr), Horseshoe (1) (ss), Lindy (rr). Mud (1) (rr). South Crab 
 (ss). Wild Goose (rr). 
 
 An alga that resembles C. stipitatum in the manner of growth but 
 one which is found upon a wider range of genera. It also differs in the 
 curved cells and the broader stipe. 
 
WISCONSIN PHYTOPLANKTON 
 
 177 
 
 Characium cylindricum Lambert. PI. 49, Pigs. 16-19. 
 Rhodora 11 : 70, pi. 79, figs. 1-2, 7-8, 10-13, 23-25. 1909. 
 
 Cells cylindrical, with rounded apices, base tapering slightly into a 
 short stipe without a basal disc. Chloroplasts 1-16, parietal, disciform 
 to laminate, without pyrenoids. (Euplanktont). 
 
 On Diaphanosoma hrachyura and Branchipus vernalis. 
 
 Cells 8-20 fjL broad, 20-430 /a long. 
 
 Howey (cc). 
 
 - The lack of a pyrenoid suggests Characiopsis but the bright green 
 color of the chloroplast shows that the alga is one of the Chlorophyceae 
 and so is placed among Cho/racium species. Young cells contain a sin- 
 gle chloroplast but with growth there is an increase in the number of 
 chloroplasts and all stages between cells with a single chloroplast and 
 those with sixteen may be found on the same crustacean. Lambert 
 holds that this condition is a stage in the division into zoospores but 
 in my opinion it is the normal condition of the adult cell. Another 
 point of interest is the position of the alga upon the host since it is 
 only found on the tail of the crustacean. 
 
 Characium limneticum Lemmermann. PI. 49, Figs. 25-29. 
 
 Bot. Not. 1903: 81, pi. 3, figs. 7-10. 1903. 
 
 Cells broadly fusiform, lunate, rarely straight; apex produced into 
 a single delicate hyaline seta ; base a delicate stipe without basal discs. 
 1-8 parietal band-shaped chloroplasts, each containing 1-2 pyrenoids. 
 (Euplanktont). 
 
 Cells 5-14 /A broad, 25-110 /a long ; stipe 5-10 /a long. 
 
 On Diaphanosoma hrachyura. 
 
 Boulder (rr). Browns (rr), Delavan (rrr). 
 
 Lemmermann describes the chloroplast as single but reports a divi- 
 sion of the chloroplast prior to division. I have found that in all nor- 
 mal adult cells of C. limneticum, C. gracilipes, and C. cylindricum there 
 is more than one chloroplast. 
 
 The species is very closely related to C. gracilipes but is much 
 smaller, proportionally broader, and has a simple stipe. It is very 
 probable that Raphidium longissimum var. septatum Chodat {Ankistro- 
 desmus longissimum var. septatum (Chodat) Brunnthaler) is a cell of 
 C. limneticum broken off from the crustacean during collection. 
 
 12 
 
178 
 
 WISCONSIN PHYTOPLANKTON 
 
 Characium gracilipes Lambert. PI. 49 , Figs. 20 - 24 . 
 
 Rhodora 11: 65, pi. 79, figs. 3-6, 9, 14-22. 1909. 
 
 Cells straight or curved with the median portion fusiform; apex 
 tapering into a long seta and base attenuated to a filiform stipe. Chloro- 
 plast parietal, band-shaped, 1-32 per cell; with one pyrenoid in each 
 chloroplast. ( Euplanktont) . 
 
 On Diaphanosoma hrachyura. 
 
 Cells 5-14 /X broad, 70-480 /x long. 
 
 Howey (cc). 
 
 This alga was found on the same organism and at the same time as 
 C. cylindricum. It was confined to the forward appendages while 
 C. cylindricum was found at the tail only. 
 
 Order ULOTMCHALES. 
 
 Cells usually in a simple or branched thallus, rarely forming disci- 
 form thalli one cell in thickness. Thallus generally attached, rarely 
 free-floating; naked, or enclosed by a tough and leathery or copious 
 and gelatinous, homogeneous or lamellated envelope. Cells generally 
 with a single parietal laminate to cup-shaped chloroplast with one or 
 more pyrenoids. Cell shape usually cylindrical with flattened ends, 
 rarely cylindrical with rounded ends, spherical or cubical. 
 
 Asexual reproduction by vegetative cell division, by a division of 
 vegetative or special cells to form 2-16 bi- or tetraciliate zoospores, and 
 by aplanospores. 
 
 Sexual reproduction either isogamous by a division of ceU contents 
 to form bi- or tetraciliate zoogametes ; or heterogamous by the fusion of 
 tetraciliate zoogametes of different size or the union of large non-motile 
 oospheres and small biciliate antherozoids. 
 
 KEY TO THE FAMILIES. 
 
 Cells united to form simple filaments Ulotbjchaoeab 
 
 Cells united to form branching filaments. 
 
 Sexual reproduction by isogamoua zoogametes Chaetophoraceae 
 
 Sexual reproduction by heterogamous zoogametes Aphanochaetaceae 
 
 Family ULOTRICHACEAE. 
 
 Cells united to form simple free-floating or sessile filaments which 
 are enclosed at times by a copious, hyaline, homogeneous or radially 
 fibrillar, gelatinous envelope. Cell shape spherical to cylindrical with 
 rounded or flattened ends. Walls of cells delicate or thick, homogen- 
 
WISCONSIN PHYTOPLANKTON 
 
 179 
 
 ecus or lamellated. Cells containing a nucleus and one parietal, lami- 
 nate or cup-shaped chloroplast with one or more pyrenoids. 
 
 Asexual reproduction by vegetative cell division, aplanospores or 
 biciliate zoospores. 
 
 Sexual reproduction isogamous, by a fusion of bi- or tetraciliate zoo- 
 gametes. 
 
 ULOTHRIX Kiitzing 1833. 
 
 Filaments simple, free-floating or with the basal cell modified to form 
 a hold-fast. Cells cylindrical, with flattened end walls, united to form 
 simple filaments that are the same diameter throughout. Wall of cells 
 delicate or thick, homogeneous or lamellated, without a gelatinous outer 
 layer. Chloroplast single, parietal, laminate, with one or more pyre- 
 noids. Cells uninucleate. 
 
 Asexual reproduction by the division of cell contents to form 1-32 . 
 aplanospores and bi- or tetraciliate zoospores. 
 
 Sexual reproduction isogamous, by a fusion of biciliate zoogametes. 
 
 KEY TO THE SPECIES. 
 
 Filaments 11-45 fi in diameter U. Zonata 
 
 Filaments 5-7 in diameter U. Subconsteicta 
 
 Ulothrix zonata (Weber & Mohr) Kiitzing. PL 50, Fig. 6. 
 Flora 16: 519. 1833; Hazen, Mem. Torr. Bot. Cl. 11: 147, pi. 20, figs. 1-4. 1902. 
 
 Filaments attached or free-floating and forming greenish masses. 
 Cells disciform to cylindrical, % to V/2 times as long as broad. End 
 walls of cells straight, side walls straiglit or slightly convex in older 
 cells. Chloroplast forming a broad or narrow pariccal annular girdle 
 containing several pyrenoids. Wall of cell thick, generally homo- 
 geneous but at times lamellated in structure. (Tychoplanktont). 
 
 Mature cells 11-45 p in diameter. 
 
 Mendota (rrr). 
 
 Ulothrix subconstricta G. S. West. PL 50, Figs. 4r-5. 
 
 Jour, of Bot. 53 : 82, figs. 6a-6c. 1915. 
 
 Filaments free-floating, narrow, slightly constricted at cross walls of 
 cells, with or without a homogeneous gelatinous envelope. Cells elon- 
 gate, 2-6 times as long as broad, slightly inflated at the poles. Chloro- 
 plast single, parietal, laminate, with irregular edges and occupying 
 the median two thirds of the cell. With or without 1-2 pyrenoids. 
 Cell wall very delicate. (Facultative Planktont). 
 
180 
 
 WISCONSIN PHYTOPLANKTON 
 
 Cells 5.7-9 broad. 
 
 The specimens that I have found in our lakes differ somewhat from 
 those described by West since the cells are not slightly dilate at the 
 poles and the chloroplasts usually contain pyrenoids. The Wisconsin 
 organism does not seem sufficiently differentiated, however, to warrant 
 the description of a new variety or species. This alga is of particular 
 interest since it is the only one of the order which has become established 
 as a true member of the plankton. 
 
 Family CHAETOPHORACEAE, 
 
 Cells united to form branching filamentous, discoidal or parenchyma- 
 tous thalli. Branches of thallus generally attenuated at apices and 
 sometimes ending in long hair-like processes. Thallus naked or en- 
 closed in a copious, hyaline, homogeneous, gelatinous envelope. Cell 
 shape ordinarily cylindrical with flattened ends. Chloroplast single, 
 parietal and laminate to girdle-shaped; with one or more pyrenoids. 
 Nucleus single. 
 
 Asexual reproduction by aplanospores and bi- or tetraciliate zoo- 
 spores. 
 
 Sexual reproduction isogamous, by a fusion of biciliate zoogametes. 
 
 STIGEOCLONIUM Kiitzing 1843. 
 
 Thallus free-floating or attached, with branches scattered and not 
 arising in dense tufts. Thallus without an appreciable difference in 
 size between the main stem and minor branches ; covered with a homo- 
 geneous, hyaline, gelatinous envelope. Cells cylindrical to disciform, 
 gradually decreasing in diameter towards the apex and with terminal 
 cells conical or elongated to hair-like unseptate processes. Chloroplast 
 single, parietal ; gridle-shaped and filling median portion of older cells ; 
 completely filling younger cells. Each chloroplast generally containing 
 several pyrenoids. 
 
 Asexual reproduction by aplanospores and tetraciliate zoospores. 
 Sexual reproduction isogamous, by the fusion of biciliate zoogametes. 
 
 Stigeoclonium lubricum (Dillwyn) Kiitzing. PI. 50, Fig. 7. 
 Phycol. germ. 189. 1845. 
 
 Myxonema liTbricum (Dillw.) Fries. Hazen, Mem. Torr. Bot. Cl. 11 : 195, 
 p/. 28, Ms. 1-2. 1902. 
 
 Filaments forming dark green tufts up to 30 cm. long. Filaments 
 much branched and branches usually opposite, rarely single. Cells of 
 main filament at base of branches sub-spherical, shorter than other cells. 
 
WISCONSIN PHYTOPLANKTON 
 
 181 
 
 Branehlets abundant, opposite, scattered in basal portion, dense in dis- 
 tal, only slightly narrower than the branch from which they arise and 
 with terminal cell conical or setiferous. Lower cells of main branch 
 swollen, %-4 times as long as broad, with a girdle-like chloroplast in 
 median portion. (Tychoplanktont). 
 
 Main branches 14-16.5 fx broad; branehlets 6-7 fx broad. 
 
 Mendota (rrr), Wild Goose (rrr). 
 
 Family APHANOCHAETACEAE. 
 
 Thallus epiphytic, generally upon other algae, creeping in habit and 
 composed of simple or irregularly branching filaments that taper from 
 the center to short, narrow terminal cells that do not end in terminal 
 setae. Central cells of filament spherical to spherical-cylindrical ; those 
 towards the end cylindrical with straight or convex sides; terminal 
 cells conical. Cells generally bearing one or more long, hyaline, un- 
 septate setae with swollen bases. Chloropast parietal, completely fill- 
 ing the cell, or gridle-like and in the median portion; generally with 
 more than one pyrenoid. 
 
 Asexual reproduction by tetraciliate zoospores or aplanospores. 
 
 Sexual reproduction heterogamous, by the fusion of tetraciliate zoo- 
 gametes that are markedly different in size. 
 
 The family contains the single genus Aphanochaete whose characters 
 are those of the family. 
 
 Aphanochaete vermiculoides WoUe. PI. 50, Fig. 8. 
 
 Freshw. algae of U. S. 119, pi. 105, figs. 9-10. 1887. 
 
 Herposteiron hyalothecae Hansgirg, G. M. Smitli, Trans. Wis. Acad. Sci., 
 Arts, & Lett. 18^: 560. 1916. 
 
 Filaments but slightly branched and confined to the peripheral por- 
 tion and twisted around or arched from the gelatinous envelope of 
 liyalotJieca filaments. Cells cylindrical, with straight or convex sides 
 and containing a single chloroplast with 1-A pyrenoids. Setae very 
 sparse, rarely more than five on any filament. (Tychoplanktont). 
 
 Cells 4^6 [I broad ; 5-12 p, long. 
 
 Beaverdam (rr). 
 
 All other species of the genus grow directly upon the cells of the 
 substratum but the wide gelatinous envelope of the Hyalotheca is in 
 this case sufficiently firm to support the Aphanochaete. The alga has 
 the appearance of an arching worm crawling along the filament. 
 
182 
 
 WISCONSIN PHYTOPLANKTON 
 
 Order SIPHONOCLADIALES. 
 
 Cells multinucleate, generally cylindrical and united to form simple 
 or branched thalli that are, at times, quite complicated in structure. 
 Chloroplasts disciform, parietal and numerous, or united by strands 
 to form a single reticulate structure. Pyrenoids generally present. 
 
 Asexual reproduction by zoospores and aplanospores. 
 
 Sexual reproduction isogamous by means of zoogametes; or heter- 
 ogamous by large non-motile oospheres and small motile antherozoids. 
 
 The order is largely marine and only one representative, CladopJim'a, 
 has been found in the plankton. 
 
 Family CLADOPHORACEAE. 
 
 Filaments generally sessile, simple or branched, with septations be- 
 tween the cells complete. Walls of cells generally heavy, homogeneous 
 or lamellose, without a gelatinous envelope. Cells with numerous 
 parietal disciform chloroplasts or a single reticulate chloroplast ; multi- 
 nucleate ; with a single large central vacuole. 
 
 Asexual reproduction by zoospores and akinetes. 
 
 Sexual reproduction isogamous, by means of zoogametes. 
 
 CLADOPHORA Kiitzing 1843. 
 
 Filaments branched, with the component cells in a single linear series ; 
 lateral branches arising at distal part of main branch cells and gener- 
 ally with an abundantly developed system of branching. Growth of 
 filaments confined to the apical region. Cells cylindrical, several times 
 as long as broad; multinucleate; with numerous parietal disciform 
 chloroplasts or the chloroplasts united by processes to form a single 
 reticulate chloroplast; pyrenoids numerous. 
 
 Asexual reproduction by the formation of many biciliate zoospores in 
 any cell of the filament. 
 
 Sexual reproduction isogamous, by means of biciliate zoogametes. 
 
 Cladophora glomerata (L.) Kiitzing. PI. 50, Figs. 1-3. 
 
 Phycol. gener. 266. 1843; Collins, Tufts Coll. Studies 2: 350, pi. 13, fig- 124. 
 1909. 
 
 Branching of filaments fairly dense in lower portion and very dense 
 at the apex. Ultimate branchlets containing several cells, straight or 
 slightly incurved, with ends rounded but not markedly attenuated. 
 Cells of main branches 6-7 times as long as broad, 3-6 times as broad 
 
WISCONSIN PHYTOPLANKTON 
 
 183 
 
 as branchlets. Zoospore formation confined to terminal and subtermi- 
 nal cells. (Tychoplanktont). 
 
 Diam. main cells 75-100 />t, branchlets 35-50 fi. 
 
 Mendota (rr). 
 
 Division AKONTAE. 
 
 Cells solitary or in filaments, variously shaped, with one or more 
 grass-green chloroplasts that usually contain more than one pyrenoid. 
 
 Asexual reproduction ordinarily by vegetative cell division, rarely by 
 aplanospores, never by zoospores. 
 
 Sexual reproduetion isogamous, always by aplanogametes, never by 
 ciliate zoogametes. 
 
 The lack of cilia in every type of reproduction is the great character- 
 istic of the division. It includes but one order, the Conjugates, which 
 forms a very homogeneous though diverse group. 
 
 Order CONJUGALES. 
 
 Cells solitary or in simple filaments; cell shape various, cylindrical 
 without median constrictions or bilaterally symmetrical and usually 
 with a median constriction dividing the cell into two symmetrical halves. 
 Cell wall smooth or variously ornamented, with an inner firm portion 
 and an outer gelatinous portion that is very copious at times. Chloro- 
 plasts 1-8, variously shaped, axial or parietal, with one to several pyre- 
 noids. Nucleus single, at the center of the cell. 
 
 Asexual reproduction by vegetative cell division or aplanospores. 
 
 Sexual reproduction isogamous, by aplanogametes. 
 
 KEY TO THE FAMILIES. 
 
 Cells cylindrical, without a median constriction, united to 
 
 form simple filaments Zygnemaceae 
 
 Cells solitary or in filaments, divided into two symmetri- 
 cal halves, generally with a median constriction Desmidiaceae 
 
 (See Fart II) 
 
 Family ZYGNEMACEAE. 
 
 Cells always cylindrical, with ends flattened or replicate, serially 
 arranged to form simple filaments that occasionally have simple lateral 
 outgrowths. Filaments generally free-floating though at times attached 
 by a modification of terminal cell into a basal cell with short rhizoidal 
 processes. Wall of cell firm, homogeneous, with a narrow or copious, 
 homogeneous or radially fibrillar, gelatinous covering. Cell contents 
 consisting of a single nucleus, and one to several chloroplasts that are 
 
184 
 
 WISCONSIN PHYTOPLANKTON 
 
 either stellate or laminate and axial or parietal. Chloroplasts with one 
 to many pyrenoids. 
 
 Asexual reproduction by vegetative cell division or metamorphosis 
 of cell contents into a single large aplanospore. 
 
 Sexual reproduction isogamous, by metamorphosis of all or a part 
 of the cell contents into an aplanogamete which fuses with an aplano- 
 gamete from the same or another filament. Zygote with 2-3 layers, 
 sometimes germinating immediately but usually after a period of rest. 
 
 KEY TO THE GENERA. 
 
 Chloroplast stellate Zygnema 
 
 Chloroplast a longitudinal band. 
 
 Chloroplast axial Mougeotia 
 
 Chloroplast parietal Spieogyea 
 
 MOUGEOTIA C. A. Agardh 1824. 
 
 Cells cylindrical, generally several times as long as broad. Chloro- 
 plast single, forming an axial plate extending the whole length of the 
 cell and generally with several pyrenoids. 
 
 Conjugation generally scalariform and with the zygote formed in the 
 conjugation tube. Zygote at times occupying the median portion of 
 male and female gametangia as well as conjugation tube. Wall of 
 zygote of two layers the inner smooth, the outer smooth or sculptured, 
 hyaline or colored. 
 
 Mougeotia viridis (Kutzing) Wittrock. PI. 51, Fig. 1. 
 
 Bih. Kgl. Sv. Vet.-Ak. Handl. 1 , No. 1 : 39. 1872. 
 
 Staurospermum viride Kutzing. Cooke, Brit. Freshw. Algae 107, pi. 44, 
 figs. 2a-2c. 1882. 
 
 Cells 4-10 times as long as broad. Zygospores normally bounded by 
 four cells, quadrangular, with concave sides and truncate corners. 
 ( Tychoplanktont) . 
 
 Cells 6-8 fi broad. Zygotes 22-32 p, broad. 
 
 Okauchee (rrr). 
 
 ZYGNEMA C. A. Agardh 1817. 
 
 Cells cylindrical, rarely more than twice as broad as long. Filaments 
 with a terminal cell at times modified to form a holdfast. Cells with 
 one nucleus and two axial stellate chloroplasts each of which contain 
 a single pyrenoid. Conjugation lateral or scalariform, with a forma- 
 tion of zygospores in the conjugation tube or the gametangia. Zygotes 
 ipherical to ellipsoid, wall with three layers. 
 
WISCONSIN PHYTOPLANKTON 
 
 185 
 
 Zygnema pectinatum (Vauclier) C. A. Agardh. PI. 51, Fig. 2. 
 
 Synop. algarum Scand. 102. 1817; DeBary, Unters. u. d. Fam. d. Conjugaten. 
 77, pi, 1, figs. 15-19. 1858. 
 
 Vegetative cells 1-3 times as broad as long. Zygospore formed in 
 conjugation tube, with rounded ends. Middle layer of zygote wall 
 brown and scrobiculate. (Tychoplanktont). 
 
 Vegetative cells 30-40 fi broad. Zygote 35-40 fx broad. 
 
 Oconomowoc (rrr). 
 
 SPIROGYRA Link 1820. 
 
 Cells cylindrical, with end walls a flat plane or replicate; united to 
 form simple filaments that may be attached by a modification of the 
 terminal cell into holdfasts. Length of cells slightly greater than to 
 several times the breadth. Chloroplasts one to several, parietal, in 
 long ribbons that extend from end to end in the cell and generally 
 make several spiral turns. Nucleus single, moored in the center of the 
 central vacuole by cytoplasmic strands running to the pyrenoids. Chlor- 
 oplasts wdth several pyrenoids that are generally in a single median row. 
 
 Conjugation scalariform or lateral, with zygote formation in game- 
 tangia and never in the tube. Zygote spherical, ellipsoid, or cylindri- 
 cal with rounded ends. Middle layer of zygote hyaline or colored, 
 smC'Oth or sculptured. 
 
 Spirogyra porticalis (Muller) Cleve. PI. 51, Fig. 3. 
 
 Nova Acta Reg. Soc. Sci. Upsaliensis 3, Ser., 6: No. 11, 22, pi. 5, figs. 8-13. 
 1868. 
 
 Length of vegetative cells 2-6 times the breadth. Cells with plane 
 cross walls and containing a single chloroplast that makes 3-5 turns and 
 contains numerous conspicuous pyrenoids. Gametangia but little swol- 
 len when zygospore is mature. Zygospores broadly ovoid to sub-cylin- 
 drical, with a yellow membrane when mature. (Tychoplanktont). 
 
 Diam. cells 30-50 fi. Diam. zygospores 40-50 fx. 
 
 Mendota (rrr). 
 
1S6 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 1. 
 
 Page 
 
 Fig. 1. Chroococcus minutus (x 825) 28 
 
 Fig. 2. Chroococcus dispersus (x 825) 28 
 
 Fig. 3. Chroococcus dispersus var. minor (x 825) 28 
 
 Fig. 4. Chroococcus limneticus (x 825) 29 
 
 Fig. 5. Chroococcus limneticus var. suhsalsus (x 825) 29 
 
 Fig. 6. Chroococcus limneticus var. carneus (x 825) 30 
 
 Fig. 7. Chroococcus limneticus var. distans (x 825) 30 
 
 Fig. 8. Chroococcus limneticus var. elegans (x *825) 30 
 
 Fig. 9. Chroococcus turgidus (x 1000) 31 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 1 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 2 
 
 1 
 
 0000 OB 00 
 
 OOQO OQ OQ 
 
 0000 00 00 
 
 OGOQ 00 i© 
 onno On nn 
 
 Q ©o© (f 
 
 SMITH— ALGAE 
 
 COCKAVNC, BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 187 
 
 PLATE 2. 
 
 Page 
 
 Fig. 1. CUroococcus giganteus (x 825) 30 
 
 Fig. 2. Merismopedia tenuissima (x 1000) 33 
 
 Fig. 3. Merismopedia punctata (x 1000) 33 
 
 Fig. 4. Merismopedia glauca (x 1000) 32 
 
 Fig. 5. Merismopedia elegans (x 1000) 32 
 
 Fig. 6. Merismopedia elegans var. major (x 1000) 32 
 
 Fig. 7. Aphanocapsa delicatissima (x 1000) 41 
 
 Fig. 8. Aphanocapsa elachista var. conferta. (x 1000) 42 
 
 Fig. 9. Aphanocapsa pulchra (x 825) 42 
 
 Fig. 10. Aphanocapsa endophytica (x 1000) 42 
 
188 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 3. 
 
 Page 
 
 Fig. 1. Aphanocapsa Grevillei (x 825) 43 
 
 Pig. 2. Aphanocapsa rivularis (x 825) 43 
 
 Fig. 3. Aphanocapsa elachista var. planctonica (x 1000) 42 
 
 Pigs. 4-5. Coelosphaerium Kuetzingianum (x 825) 34 
 
 Fig. 6. Coelosphaerium Naegelianum (x 825) 35 
 
 Fig. 7. Coelosphaerium duhium (x 825) 35 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 3 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 4 
 
 SMITH — ALGAE 
 
WISCONSIN PHYTOPLANKTON 
 
 189 
 
 PLATE 4. 
 
 Page 
 
 Fig. 1. Coelosphaerium Naegelianum (x 825) 35 
 
 Figs, 2-3. Gomphosphaeria aponina (x 825) 37 
 
 Fig. 4. Gomphosphaeria aponina var. cordiformis (x 825) 37 
 
 Fig. 5. Gomphosphaeria lacustris (x 825) 36 
 
 Fig. 6. Microcystis aeruginosa var. 'major (x 825) 40 
 
190 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 5. 
 
 Page 
 
 Figs. 1-2. Microcystis aeruginosa (Pig. 1, x 825; fig. 2, x 180 39 
 
 Fig. 3. Microcystis fios-aquae (x 825) 39 
 
 Fig. 4. Microcystis incerta (x 825) 40 
 
 Fig. 5. ApTianothece prasina (x 825) 45 
 
 Fig. 6. Aphanothece nidulans var. endophytica (x 1000) 44 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 5 
 
 SMITH — ALGAE 
 
 COCKAVNe, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 6 
 
 I 
 
 SMITH— ALGAE 
 
 COCKAYNE, BOSTON 
 
WTBOONBIN PHYTOPLANKTON 191 
 
 PLATE 6. 
 
 Page 
 
 Fig. 1. Aphanothece nidulans (x 1000) 44 
 
 Fig. 2. Aphanothece stagnina (x 825) 45 
 
 Fig. 3. Aphanothece clathrata (x 1000) 44 
 
 Fig. 4. Rhahdoderma linear e (x 1000) 47 
 
 Fig. 5. Gloeothece linearis (x 1000) 46 
 
 Fig. 6. Gloeothece linearis var. composita (x 1000) v 46 
 
 Fig. 7. Dactylococcopsis raphidioides (x 825) 47 
 
 Figs. 8-10. Dactylococcopsis acicularis (x 1000) 48 
 
192 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 7. 
 
 Page 
 
 Fig. 1. SpiruUna major (x 1000) 50 
 
 Fig. 2. SpiruUna princeps (x 1000) 50 
 
 Figs. 3-5. Oscillatoria proUfica (x 825) 51 
 
 Fig. 6. Oscillatoria tenuis (x 825) 52 
 
 Figs. 7-8. Oscillatoria tenuis var. tergestina (x 825) 52 
 
 Figs. 9-11. Lyngbya limnetica (x 1000) 52 
 
 Figs. 12-13. Lyngdya contorta (x 1000) 53 
 
 Figs. 14-15. Lyngdya Birgei (x 825) 54 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 7 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTOI 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 8 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 193 
 
 PLATE 8. 
 
 Fig. 1. Trichodesmium lacustre (x 1000) 
 
 Fig. 2. Anahaena plantonica (x 825) 
 
 Fig. 3. Anahaena Bornetiana (x 825) 
 
 Figs. 4-5. Anahaena Levanderi (x 825) 
 
 Fig. 6. Anahaena macrospora var. rohusta (x 825) . 
 
 Fig. 7. Anahaena a3'^is (x 825) 
 
 Fig. 8. Anahaena limnetica (x 825) 
 
 Figs. 9-10. Anahaena augstumalis var. marcMca (x 825) 
 
 13 
 
 Page 
 
 54 
 
 56 
 58 
 58 
 
 57 
 57 
 
 57 
 
 58 
 
194 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 9. 
 
 Page 
 
 Figs. l-i3. Anahaena spiroides var. crassa (Pig. 1, x 825, figs. 2~3, x 400) 59 
 
 Figs. 4-5. Anahaena circinalis (Fig. 4, x 825, fig. 5, x 400) 59 
 
 Fig. 6. Anahaena circinalis var. mao'ospora (x 825) 60 
 
SMITH— ALGAE 
 
 COCKAYNE, BOSTO* 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE lO 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 195 
 
 PJLATE 10. 
 
 Page 
 
 Fig. 1. Anabaena circinalis var. macrospora (x 400) 60 
 
 Figs. 2-4. Anabaena flos-aquae (Figs. 2-3, x 825; fig. 4, x 400) 60 
 
 Figs. 5-7. Anabaena fios-aquae var. Treleasii (x 825) 60 
 
 Fig. 8. Anabaena Lemmermanni (x 825) 61 
 
196 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 11. 
 
 Page 
 
 Fig. 1. Anahaena Lemmermanni (x 400) 61 
 
 Figs. 2-4. Aphanizomenon flos-aquae (Fig. 2, x 400; figs. 3-4, x 1000).. 61 
 
 Figs. 5-6. OloeotricMa ecTiinulata (x 400) 63 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 11 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 12 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 197 
 
 PLATE 12. 
 
 Page 
 
 Fig. 1. ChrysamoeM radians (x 1000) 67 
 
 Pig. 2. Mallomonas producta (x 500) 68 
 
 Fig. 3. Mallomonas producta var. marchica (x 500) 68 
 
 Fig. 4. Mallomonas alpina (x 500) 68 
 
 Fig. 5. Mallomonas tonsurata (x 500) 68 
 
 Fig. 6. Mallomonas caudata (x 500) 69 
 
 Pigs. 7-8. Chrysosphaerella longispina (Fig. 7, x 400; fig. 8, x 1000).. 69 
 
 Pigs. 9-10. Synura uvella (Pig. 9, x 1000, fig. 10, x 400) 70 
 
198 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 13. 
 
 Page 
 
 Figs. 1-4. Uroglenopsis americana (Fig. 1, x 400; figs. 2-4, x 1000) .... 71 
 
 Figs. 5-6. Dinohryon caldformis (x 1000) 73 
 
 Figs. 7-9. DinoJ)ry on tabellariae (x 1000) 73 
 
 Fig. 10. Dinolryon davaricum (x 400) 73 
 
 Fig. 11. Dinohryon stipitatum (x 400) 74 
 
 Fig. 12. Dinohryon sociale (x 400) 74 
 
 Fig. 13. Dinohryon setularia (x 400) 74 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 13 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 14 
 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN PHYTOPLANKTON 199 
 
 PLATE 14. 
 
 Page 
 
 Pig. 1. DinoJ)ryon setularia (x 400) 74 
 
 Fig. 2. Dinobryon divergens (x 400) 75 
 
 Figs. 3-4. Hyalobryon mucicola (x 1000) 75 
 
 Pig. 5. Phaeococcus plantonicus (x 1000) 76 
 
 Fig. 6. Rhizochrysis limnetica (x 400) 77 
 
 Figs. 7-8. Chrysidiastrum catenulatum (Fig. 7, x 500, fig. 8, x 1000)... 78 
 
200 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 15. 
 
 Page 
 
 Pigs. 1-3. Chlorochromonas minuta (x 1000) 80 
 
 Fig. 4. Peroniella planctonica (x 1000) 81 
 
 Fig. 5. Botryococcus Braunii (x 400) 84 
 
 Figs. 6-7. Botryococcus protuberans var. minor (Fig. 6 x 500, fig. 7 x 
 
 1000) 85 
 
 Fig. 8. Botryococcus sudeticus (x 400) 83 
 
 Fig. 9. Chlorobotrys limneticus (x 1000) 82 
 
 Fig. 10. Chlorolotrys regularis (x 1000) 82 
 
 Fig. 11. Ophiocytium parvulum (x 1000) 86 
 
 Figs. 12-13. Ophiocytium capitatum (x 1000) 86 
 
 Figs. 14-16. Ophiocytium capitatum var. longispinum (x 1000) 86 
 
 Figs. 17-18. Trihonema minus (x 1000) 87 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 15 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 16 
 
 SMITH — ALGAE 
 
 COCKAVNC, BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 201 
 
 PLATE 16. 
 
 Page 
 
 Fig. 1. Carteria cordiformis (x 1000) 92 
 
 Figs. 2-4. Carteria Elehsii (x 1000) 93 
 
 Figs. 5-7. Chlamydomonas dinohryoni (x 1000) 91 
 
 Pig. 8. Chlamydomonas glohosa (x 1000) 90 
 
 Figs. 9-10. Chlamydomonas Snowii (x 1000) 91 
 
 Figs. 11-13. Chlamydomonas epiphytica (x 1000) - 91 
 
 Figs. 14-15. Gonium pectorale (x 500) 94 
 
 Figs. 16-17. Pandorina morum (x 400) 95 
 
202 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 17. 
 
 Figs. 1-3. Pleodorina calif ornica (x 400) , 
 
 Page 
 
 97 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 17 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 18 
 
 
 
 H ^-#1^ 
 
 W<>W 
 
 
 WWi 
 
 
 
 
 
 /q 0 
 
 J© K9 
 
 a ® ® ® 
 
 J Q 0 ■ © ® ®- 
 
 „ _,_. JV ® 
 
 <d-y9r 
 
 V ^ ® 7® 
 
 4>rt '■■■© 
 
 SMITH— ALGAE 
 
 COCKAYNK, BOSTON 
 
 
WISCONSIN PHYTOPLANKTON 
 
 203 
 
 PLATE 18. 
 
 Page 
 
 Pig. 1. Yolvox mononae (x 266) 99 
 
 Fig. 2. Yolvox aureus (x 266) 98 
 
 Figs. 3-5. Yolvox fflodator (x 266) 98 
 
204 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 19. 
 
 Page 
 
 Pig. 1. Eudorina elegans (x 500) 96 
 
 Fig. 2. Gloeocystis gigas (x 1000) 101 
 
 Figs. 3-4. Sphaerocystis Schroeteri (x 1000) 101 
 
 Figs. 5-6. Tetraspora lacustris (x 500) 102 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 19 
 
 SMITH- 
 
 :0>~K N E , BOSTOM 
 
WtSCONSIN SURVEY 
 
 BULLETIN 57. PLATE 20 
 
 SMITH— ALGAE 
 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 205 
 
 PLATE 20. 
 
 Page 
 
 Figs. 1-2. Oloeocystopsis Umneticus (x 1000) 103 
 
 Figs. 3-6. Planktosphaeria gelatinosa (x 1000) 103 
 
 Pigs. 7-10. Asterococcus Umneticus (Fig. 7, x 500; figs. 8-10, x 1000) . 104 
 
 Figs. 11-12. DictyospJiaerium Ehrenhergianum (x 1000) 105 
 
 Fig. 13. Dictyosphaerium pulcTiellum (x 1000) 105 
 
206 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 21. 
 
 Page 
 
 Fig. 1. Dictyosphaerium pulchellum (x 1000) 105 
 
 Figs. 2-3. Westella linearis (x 1000) 107 
 
 Fig. 4. Westella hotryoides (x 1000) 107 
 
 Fig. 5. Dimorpiiococcus lunatus (x 1000) 106 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 21 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 22 
 
 SMITH— ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 207 
 
 PLATE 22. 
 
 Page 
 
 Fig. 1. Chlorella vutff.aris (x 1000) 108 
 
 Fig. 2. Trochiscia reticularis (x 1000) 109 
 
 Fig. 3. Oocystis pusilla (x 1000) Ill 
 
 Fig. 4. Oocystis Borgei (x 1000) Ill 
 
 Fig. 5. Oocystis clliptica (x 1000) Ill 
 
 Fig. 6. Oocystis parva (x 1000) 112 
 
 Fig. 7. Oocystis gloeocystijormis (x 1000) 112 
 
 Figs. 8-9. Oocystis lacustris (x 1000) 112 
 
 Fig. 10. Oocystis sulymarina (x 1000) 113 
 
 Fig. 11. Oocystis solitaria (x 1000) 113 
 
 Figs. 12-13. Oocystis crassa (x 1000) 113 
 
208 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 23. 
 
 Page 
 
 Pigs. 1-2. Oocystis eremosphaeria (x 1000) 113 
 
 Fig. 3. OoXyystis panduriformis var. minor (x 1000) 114 
 
 Figs. 4-5. Oocystis natans var. major (Fig. 4, x 500; fig. 5, x 1000).. 114 
 
 Figs. 6-7. NepTirocytium Agardhianum (x 1000) 114 
 
 Figs. 8-9. Oloeotaenium Loitleshergerianum (x 400) 115 
 
 Pigs. 10-13. Tetraedron muticum var. punctulatum (x 1000) 116 
 
 Figs. 14-16. Tetraedron trigonum (x 1000) 116 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 23 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 24 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 209 
 
 PLATE 24. 
 
 Page 
 
 Figs. 1-4. Tetraedron trigonum var. setigerum (x 1000) 117 
 
 Figs. 5-9. Tetraedron trigonum var. gracile (x 1000) 117 
 
 Pigs. 10-13. Tetraedron yninimum (x 1000) 118 
 
 Fig. 14. Tetraedron regular e (x 1000) 118 
 
 Figs. 15-16. Tetraedron regulare var. incus (x 1000) L18 
 
 Pigs. 17-18. Tetraedron regulare var. torsum (x 1000) 119 
 
 Figs. 19-22.. Tetraedron victorieae var. major (x 1000) 119 
 
 14 
 
210 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 25. 
 
 Page 
 
 Fig. 1. Tetraedron victorieae var. major (x 1000) 119 
 
 Figs. ;2-3. Tetraedron verrucosum (x 1000) 119 
 
 Figs. 4-7. TetraMron caudatum (x 1000) 120 
 
 Figs. 8-12. Tetraedron eaudatum var. longispinum (x 1000) 120 
 
 Figs. 13-17. Tetraedron pentaMrieum (x 1000) 120 
 
 Fig. 1^. TetraMron hastatum (x 1000) 121 
 
 Figs. 19-21. Tetraedron hastatum var. palatinum (x 1000) 121 
 
 Figs. 22-24. Tetraedron constrictum (x 1000) 122 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 25 
 
 SMITH — ALGAE 
 
 COCKAYNE 
 
 BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 26 
 
 SMITH — ALGAE 
 
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WISCONSIN PHYTOPLANKTON 211 
 
 PLATE 26. 
 
 Page 
 
 Figs. 1-5. TetraMron gracile (x 1000) 122 
 
 Figs. 6-7. Tetraedron lohulatum (x 1000) 122 
 
 Pig. 8. Tetraedron lolulatum var. polyfurcatum (x 1000) 123 
 
212 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 27. 
 
 Page 
 
 Figs. 1-3. Tetraedron limneticum (x 1000) 123 
 
 Figs. 4-5. Tetraedron planctonicum (x 1000) 123 
 
 Fig. 6. Tetraedron enorme (x 1000) 124 
 
 Figs. 7-8. Polyedriopsis spinulosa (x 1000) 124 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 27 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 28 
 
 SMITH— ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 213 
 
 PLATE 28. 
 
 Page 
 
 Figs. 1-3. Micractinium pusillum (x 1000) 125 
 
 Fig. 4. Micractinium quadrisetum (x 1000) 126 
 
214 
 
 WI8G0N8IN PHYTOPLANKTOIi^ 
 
 PLATS 29. 
 
 Page 
 
 Fig. 1. Micractinium pusillum var. elegans (x 1000) 126 
 
 Figs. 2-3. Golenkinia radiata (x 1000) 127 
 
 Figs. 4-5. Golenkinia paucispina (x 1000) 127 
 
 Figs. 6-8. Acanthosphaera Zachariasi (x 1000) 128 
 
 Figs. 9-11. E Chino spTiaerella limnetica (x 1000) 128 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 29 
 
 SMITH — ALGAE 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 30 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 215 
 
 PLATE 30. 
 
 Page 
 
 Figs. 1-2. Lagerheimia citriformis (x 1000) 130 
 
 Figs. 3-4. Lagerheimia suhsala (x 1000) 130 
 
 Figs. 5-7. Lagerheimia Droescheri (x 1000) 131 
 
 Figs. 8-9. Lagerheimia longiseta (x 1000) 130 
 
 Figs. 10-12. Lagerheimia longiseta var. major (x 1000) 130 
 
216 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 31. 
 
 Page 
 
 Figs. 1-2. Lagerheimia ciliata (x 1000) 129 
 
 Fig. 3. Lagerheimia ciliata var. minor (x 1000) 129 
 
 Fig. 4. Franceia ovalis (x 1000) 131 
 
 Fig. 5. Selenastrum gracile (x 1000) 133 
 
 Figs. 6-7. Selenastrum Bihraianum (x 1000) 133 
 
 Figs. 8-10. Selenastrum Westii (x 1000) 133 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 3! 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 32 
 
 COCKAYNE, BOSTON 
 
 
WISCONSIN PHYTOPLANKTON 
 
 217 
 
 PLATE 32. 
 
 Page 
 
 Fig. 1. Ankistrodesmus falcatus (x 1000) 134 
 
 Fig. 2. Ankistrodesmus falcatus var. tumidus (x 1000) 135 
 
 Figs. 3-5. Ankistrodesmus falcatus var. miraMlis (x 1000) 135 
 
 Figs. 6-7. Ankistrodesmus spiralis i(x 1000) 135 
 
 Fig. 3. Closteriopsis longissima var. tropica (x 400) 136 
 
 Figs. 9-11. Schroederia Judayi (x 1000) 137 
 
 Fig. 12. Schroederia setigera (x 1000) 137 
 
218 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 33. 
 
 Page 
 
 Figs. 1-2. Quadrigula Pfitzeri (x 1000) 138 
 
 Fig. 3. Quadrigula Chodati (x 1000) 138 
 
 Figs. 4-6. Quadrigula lacustris (Fig. 4, x 500; figs. 5-6, x 1000) 139 
 
 Fig. 7. Elaktothrix viridis (x 825) 140 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 33 
 
 SMITH— ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 34 
 
 SMITH — ALGAE 
 
 COCKAVNC. BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 219 
 
 PLATE 34. 
 
 Page 
 
 Figs. 1-3. Elaktothrix gelatinosa (Figs. 1-2, x 500; fig. 3, x 1000) 139 
 
 Fig. 4. Kirchneriella lunaris (x 1000) 141 
 
 Fig. 5. Kirchneriella lunaris var. dianae (x 100 141 
 
220 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 35. 
 
 Fig- 1. Kirchneriella lunaris var. irregularis (x 1000) 
 
 Figs. 2-3. Kirchneriella ohesa (x 1000) 
 
 Fig. 4. Kirchneriella ohesa var. major (x 1000) 
 
 Figs. 5-6. Kirchneriella ohesa var. aperta (x 1000) 
 
 Fig. 7. Kirchneriella contorta (x 1000) 
 
 Page 
 
 142 
 
 142 
 
 142 
 
 143 
 143 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 35 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 36 
 
 SMITH — ALGAE 
 
 COCKAVNE. BOSTOf^ 
 
WISCONSIN PHYTOPLANKTON 
 
 221 
 
 PLATE 36. 
 
 Page 
 
 PMgs. 1-2. Kirchneriella elongata (x 1000) 143 
 
 Pig. 3. Crucigenia rectangularis (x 1000) 144 
 
 Figs. 4-5. Crucigenia irregularis (x 1000) 145 
 
 Fig. 6. Crucigenia crucifera (x 1000) 145 
 
 Figs. 7-9. Crucigenia truncata (x 1000) 146 
 
 Figs. 10-14. Crucigenia quadrata (x 1000) 147 
 
222 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 37. 
 
 Page 
 
 Fig. 1. Crucigenia apiculata (x 1000) 146 
 
 Fig. 2. Crucigenia tetrap'-ciia (x 1000) 147 
 
 Pig. 3. Crucigenia fenstrata (x 1000) 148 
 
 Fig. 4. Crucigenia Lauterhornei (x 1000) 148 
 
 Pigs. 5-6. Tetrastrum staurogeniaeforme (x 1000) 149 
 
 Figs. 7-11. Tetradesmus wisconsinensis (x 1000) 150 
 
 Figs. 12-14. Scenedesmus oMiquus (x 1000) 151 
 
 Figs. 15-17. Scenedesmus dimorphus (x 1000) 151 
 
 Figs. 18-20. Scenedesmus Hjuga (x 1000) 152 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 37 
 
 SMITH— ALGAE 
 
 COCKAYNE. BOSTOl 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 38 
 
 SMITH — ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN PHYTOPLANKTON 223 
 
 PLATE 38. 
 
 Page 
 
 Figs. 1-4. Scenedesmus acuminatus (x 1000) 152 
 
 Figs. 5-9. Scenedesmus Bernardii (x 1000) 152 
 
 Figs. 10-11. Scenedesmus Mjuga var. alternans (x 1000) 153 
 
 Figs. 12-14. Scenedesmus arcuatus (x 1000) 153 
 
 Figs. 15-16. Scenedesmus arcuatus var. capitatus (x 1000) 153 
 
224 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 39. 
 
 Page 
 
 Figs. 1-3. Scenedesmus arcuatus var. platydisca (x 1000) 154 
 
 Figs. 4-6. Scenedesmus acutiformis (x 1000) 154 
 
 Figs. 7-10. Scenedesmus armatus (x 1000) 154 
 
 Fig. 11. Scenedesmus armatus var. major (x 1000) 155 
 
 Figs. 12-14. Scenedesmus hrasiliensis (x 1000) 155 
 
 Figs. 15-16. Scenedesmus Tiystrix (x 1000) 155 
 
 Figs. 17-19. Scenedesmus denticulatus (x 1000) 155 
 
 Figs. 20-22. Scenedesmus longus (x 1000) 156 
 
 Figs. 23-25. Scenedesmus ahundans (x 1000) 157 
 
 Figs. 26-27. Scenedesmus ahundans var. longicauda (x 1000) 157 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 39 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 40 
 
 COCKAYNE, OOSTOi 
 
-WISCONSIN PHYTOPLANKTON 
 
 225 
 
 
 PLATE 40. 
 
 Page 
 
 Pigs. 1-2. Scenedesmus longus var. Naegelii (x 1000) 156 
 
 Figs. 3-5. Scenedesmus ahundans var. hrevicauda (x 1000) 157 
 
 Figs. 6-8. Scenedesmus ahundans var. asymmetrica (x 1000) 157 
 
 Figs. 9-11. Scenedesmus quadricauda (x 1000) 158 
 
 Figs. 12-14. Scenedesmus quadricauda var. longispina (x 1000) 159 
 
 Figs. 15-16. Scenedesmus quadricauda var. quadrispina (x 1000) 158 
 
 Fig. 17. Scenedesmus quadricauda var. parvus (x 1000) 158 
 
 15 
 
226 
 
 WISCONSIN PITYTOPLANKTON 
 
 PLATE 41. 
 
 Page 
 
 Figs. 1-2. Scenedesmus quadricauda var. maximus (x 1000) 159 
 
 Figs. 3-7. Scenedesmus quadricauda var. Westii (x 1000) 159 
 
 Figs. 8-11. Scenedesmus opoliensis (x 1000) 159 
 
 Figs. 12-13. Coelastrum microporum (x 825) 160 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 41 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57. PLATE 42 
 
 SMITH — ALGAE 
 
 COCKAVNC, BOSTON 
 
WISCONSIN PHYTOPLANKTON 
 
 227 
 
 PLATE 42. 
 
 Page 
 
 Fig. 1. Coelastrum microporum (x 825) 160 
 
 Figs. 2-3. Coelastrum camT)ricum (x 825) 161 
 
 Figs. 4-6. Coelastrum reticulatum (x 825) 161 
 
 Figs. 7-8. Coelastrum prohoscideum (x 825) 162 
 
228 
 
 WISCONSIN PHYTOPLANKTON 
 
 
 PLATE 43. 
 
 Page 
 
 Figs. 1-2. Coelastrum prohoscideum (x 825).. 162 
 
 Figs. 3-5. Actinastrum gracillimum (x 1000) 164 
 
 Figs. 6-7. Actinastrum HantzscM (Fig. 6, x 500; fig. 7, x 1000) 164 
 
 Fig. 8. Actinastrum HantzscM var. elongatum (x 1000) 165 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 43 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 44 
 
 SMITH — ALGAE 
 
 COCKAVNC. BOSTOlM 
 
WISCONSIN PHYTOPLANKTON 
 
 229 
 
 PLATE 44. 
 
 Page 
 
 Fig. 1. Sorastrum americanum (x 1000) 163 
 
 Figs. 2-3. Sorastrum americanum var. undulatum (x 1000) 163 
 
 PMgs. 4-5. Sorastrum spinulostim (x 1000) 163 
 
 Fig. 6. Hydrodictyon reticulatum (x 100) 166 
 
 { 
 
 r 
 
230 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 45. 
 
 Page 
 
 Fig. 1. Hydrodictyon reticulatum (x 266) 166 
 
 Figs. 2-6. Pediastrum simplex var. duodenarium (x 333) 167 
 
 Pig. 7. Pediastrum integrum (x 333) 168 
 
 Figs. 8-10. Pediastrum integrum var. priva (x 666) 168 
 
 Fig. 11. Pediastrum araneosum (x 333) 168 
 
 Figs. 12-13. Pediastrum araneosum var. rugulosum (Fig 12, x 333, 
 
 fig. 13, X 666) 
 
 168 
 
SMITH 
 
 WISCONSIN SURVEY 
 
 BULLETIN 
 
 57, PLATE 45 
 
 10 
 
 ALGAE 
 
 COCKAYNE, BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 46 
 
 SMITH — ALGAE 
 
 COCKAYNC, BOSTOi 
 
WISCONSIN PHYTOPLANKTON 
 
 231 
 
 PLATE 46. 
 
 Page 
 
 Fig. 1. Pediastrum sculptatum (x 333) 169 
 
 Figs. 2-7. Pediastrum Boryanum (x 333) 169 
 
 Fig. 8. Pediastrum Boryanum var. undulatum (x 333) 170 
 
 Fig. 9. Pediastrum Boryanum var. longicorne (x 333) 170 
 
 Figs. 10-13. Pediastrum Eawraiskyi (x 33S; 170 
 
 Figs. 14-16. Pediastrum duplex (x 333) 171 
 
 Fig. 17. Pediastrum duplex var. roiundatum (x 333) 172 
 
232 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 47. 
 
 Page 
 
 Figs. 1-3. Pediastrurti duplex var. clathratum (x 333) 171 
 
 Figs. 4-7. Pediastrum duplex var. reticulatum (x 333) 172 
 
 Figs. 8-11. Pediastrum duplex var. gracillimum (x 333) 172 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 47 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 48 
 
 SMITH — ALGAE 
 
 COCKAVNK 
 
 BOSTOM 
 
WISCONSIN PHYTOPLANKTON 233 
 
 PLATE 48. 
 
 Page 
 
 Pigs. 1-2. Pediastrum duplex var. gracillimum (x 333) 172 
 
 Pigs. 3-4. Pediastrum duplex var. cohaerens (x 333) 173 
 
 Pigs. 5-8. Pediastrum biradiatum (x 333) 173 
 
 Pigs. 9-12. Pediastrum tetras (x 666) 173 
 
 Figs. 13-14. Pediastrum tetras -var. tetrabdon (x 686) 174 
 
234 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 49. 
 
 Page 
 
 Pigs. 1-2. Pediastrum tetras var. tetraodon (x 1000).... 174 
 
 Fig. 3. Eaustropsis RicJiteri (x 1000) 175 
 
 Figs. 4-7. Characium stipitatum (x 1000) 176 
 
 Figs. 8-15. Characium curvatum (x 1000) 176 
 
 Figs. 16-19. Characium cylindricum (Fig. 16, x 400; figs. 17-19, x 
 
 1000) 177 
 
 Figs. 20-24. Characium gracilipes (x 1000) 178 
 
 Figs. 25-29. Characium limneticum (x 1000) 177 
 
COCKAYNE. BOSTON 
 

 WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 50 
 
 SMITH— ALGAE 
 
 n 
 
 
 COCKAVNC. BOSTON 
 
WISCONSIN PHYTOPLANKTON 235 
 
 PLATE 50. 
 
 Page 
 
 Figs. 1-3. Cladophora glomerata (Figs. 1-2, x 50, fig. 3, x 300) 182 
 
 Figs. 4-5. Ulothrix suJ)constricta (x 1000) 179 
 
 Fig. 6. Ulothrix zonata (x 400) 179 
 
 Fig. 7. Stigeoclonium luhricum (x 300) 180 
 
 Fig. 8. Aphanochaete vermiculoides (x 400) 181 
 
236 
 
 WISCONSIN PHYTOPLANKTON 
 
 PLATE 51. 
 
 Page 
 
 Fig. 1. Mougeotia viridis (x 400) 184 
 
 Fig. 2. Zygnema pectinatum (x 400) 185 
 
 Fig. 3. Spirogyra porticaUs (x 400) 185 
 
WISCONSIN SURVEY 
 
 BULLETIN 57, PLATE 5 
 
 SMITH — ALGAE 
 
 COCKAYNE. BOSTON 
 

 \ 
 
 OF THE 
 
 UNIVERSITY OF (LIINOIS 
 
 
 I 
 
INDEX 
 
 Page 
 
 Acanthococcus reticularis Reinsch. .. 109 
 
 ACANTHOSPHAERA Lemm 128 
 
 A. ZACHARIASI Lemm. pi. 29, f. 6-8. . 128 
 
 ACTINASTRUM Lag 164 
 
 A. GRACILLIMUM G. M. Smith pi. 
 
 ^3, f. S-5 164 
 
 A. HANTZSCHI Lag. pi. ^5, f. 6-7 164 
 
 V. ELONGATUM G. M. Smith pi. J,3, 
 
 f. 8 165 
 
 AKONTAE 183 
 
 ANABAENA Bory 55 
 
 A. AFFINIS Lemm. pi. 8, f. 7 57 
 
 A. AUGSTUMALIS v. MARCHICA 
 
 Lemm. pi. 8, f. 9-10 58 
 
 A. BORNETIANA Collins pi. 8, f. S. . 58 
 
 A. CIRCINALIS (Ktz.) Rab. pi. 9, 
 
 f. i-5 59 
 
 V. MACROSPORA (Wittr.) de Toni 
 
 pi. 9, f. 6; pi. JO, f. jf 60 
 
 A. FLOS- AQUAE (Lyng.) Breb. pi. 10, 
 
 f. 2-4 60 
 
 A. fios-aquae Klebh. non (Lyng.) 
 
 Breb 61 
 
 V. TRELEASII Born. & Flah. pi. 10, 
 
 f. 5-7 60 
 
 A. Hassallii (Ktz.) Wittr 59 
 
 V. macrospora Wittr 60 
 
 A. LEMMERMANNI P. Richt. pi. 10, 
 
 f. 8; pi. JJ, f. J Cl 
 
 A. LEVANDERI Lemm. pi. 8, f. 4-5. . 58 
 
 A. LIMNETIC A G. M. Smith pi. 8, f. 8 57 
 
 A. MACROSPORA v. ROBUSTA 
 
 Lemm. pi. 8, f. 6 57 
 
 A. mendotae Trelease 60 
 
 A. PLANCTONICA Brunnth. pi. 8, t. 2 56 
 
 A. SPIROIDES V. CRASSA Lemm. 
 
 pi. 9, f. 1-S 59 
 
 Anacystis pulverus Wood 40 
 
 ANKISTRODESMUS Corda 134 
 
 A. Chodati (Tanner-Fullman) 
 
 Brunnth 138 
 
 A. FALCATUS (Corda) Ralfs 
 
 pi. 32, f. J 134 
 
 V. ACICULARIS (A. Br.) 
 
 G. S. West 135 
 
 V. MIRABILIS (W & G. S. West) 
 
 G. S. West pi. 32, f. 3 — 5 135 
 
 V. spiralis (Turn.) G. S. West. . . 135 
 V. TUMIDUS (W. & G. S. West) 
 
 G. S. West pi. 32, f. 2 135 
 
 Page 
 
 A. lacustre (Chodat) Ostenfeld 139 
 
 A. longissimum v. septatum 
 
 (Chodat) Brunnth 177 
 
 A. Pfitzeri (Schrod.) G. S. West 138 
 
 A. SPIRALIS (Turn.) Lemm. 
 
 pi. 32, f. 6—7 135 
 
 APHANIZOMENON Morren 61 
 
 A. FLOS-AQUAE (L.) Ralfs 
 
 pi. 11, f. 2—4 61 
 
 APHANOCHAETACEAE 181 
 
 APHANOCHAETE A. Br 181 
 
 A. VERMICULOIDES Wolle 
 
 pi. 50, f. 8 181 
 
 APHANOCAPSA Nag 41 
 
 A. DELICATISSIMA W. &. G. S. 
 
 West pi. 2, f. 7 41 
 
 A. ELACHISTA v. CONFERTA 
 
 W. & G. S. West pi. 2, f. 8 42 
 
 V. PLANCTONICA G. M. 
 
 Smith pi. 3, f. 3 42 
 
 A. ENDOPHYTICA G. M. Smith 
 
 pi. 2, f. JO 42 
 
 A. GREVILLEI (Haas.) Rab. 
 
 pi. 3, f. J 43 
 
 A. PULCHRA (Ktz.) Rab. pi. 2, f. 9. 42 
 
 A. RIVULARIS (Carm.) Rab. 
 
 pi’. 3, f. 2 43 
 
 APHANOTHECE Nag 43 
 
 A. CLATHRATA W. & G. S. West 
 
 pi. 6, f. 3 44 
 
 A. NIDULANS P. Richt. pi. 6, f. J 44 
 
 V. ENDOPHYTICA W. & G. S. 
 
 West pi. 5, f. 6 44 
 
 A. PR A SIN A A. Br. pi. 5, f. 5 45 
 
 A. STAGNINA (Spreng.) A. Br. 
 
 pi. 6, £. 2 45 
 
 ASTEROCOCCUS Scherffel 103 
 
 A. LIMNETICUS G. M. Smith 
 
 pi. 20, f. 7— JO 104 
 
 Autocolony 109 
 
 AUTOSFORACEAE 109 
 
 Autospore 109 
 
 BOTRYOCOCCACEAE 83 
 
 BOTRYOCOCCUS Ktz 83 
 
 B. BRAUNII Ktz. pi. J5, f. 5 84 
 
 B. Braunii G. S. West non Ktz 83 
 
 B. PROTUBERANS v. MINOR 
 
 G. M. Smith pi. 15, f. 6—7 85 
 
 B. SUDETICUS Lemm. pi. 15, t. 8 83 
 
 CARTERIA Diesing 92 
 
238 
 
 INDEX 
 
 Page 
 
 C. CORDIFORMIS (Carter) Diesing 
 
 pi, 16, f. 1 92 
 
 C. KLEBSII (Dang.) Dill 
 
 pi. 16, f. 2 — If 93 
 
 CARTERIACBAE 92 
 
 CHAETOPHORACEAE 180 
 
 CHARACIUM A. Br 175 
 
 C. CURVATUM G. M. Smith 
 
 pi. Jfi, f. 8 — 15 176 
 
 C. CYLINDRICUM Lamb. 
 
 pi. ^9, f. 16—19 177 
 
 C. GRACIDIPES Lamb. pi. J,9, f. 20—24 178 
 C. LIMNETICUM Lemm. 
 
 pi. 49, f. 25 — 29 177 
 
 C. STIPITATUM (Bachman) Wille 
 
 pi. 49, f. 4—7 176 
 
 CHLAMYDOMONADACEAE 90 
 
 CHLAMYDOMONAS Ehr 90 
 
 C. communis Snow 91 
 
 C. DINOBRYONI G. M. Smith 
 
 pi. 16, f. 5—7 91 
 
 C. EPIPHYTICA G. M. Smith 
 
 pi. 16, f. 11— IS 91 
 
 C. GLOBOSA Snow pi. 16, f. 8 90 
 
 C. SNOWII Printz pi. 16, f. 9 — 10. ... 91 
 
 CHLORAMOEBACEAE 79 
 
 CHLORELLA Beyerinck 108 
 
 C. VULGARIS Beyerinck pi. 22, f. 1 .. . 108 
 
 CHLOROBOTRYDACEAE 82 
 
 CHLOROBOTRYS Bohlin 82 
 
 C. LIMNETICUS G. M. Smith 
 
 Page 
 
 C. MINUTUS (Ktz.) Nag. pi. 1 , f. 1 . . . 28 
 
 C. TURGIDUS (Ktz.) Nag. pi. 1 , f. 9 . 3 i 
 
 CHRYS AMOEBA Klebs 67 
 
 C. RADIANS Klebs pi. 12 , f. 1 67 
 
 CHRYSIDASTRUM Lauterborn 78 
 
 C. CATENTATUM Lauterborn 
 
 pi. 14, f. 7—8 78 
 
 CHRYSOMONADINEAE 65 
 
 CHRYSOSPHAERELLA Lauterborn 69 
 
 C, LONGISPINA Lauterborn 
 
 pi. 12, f. 7—8 69 
 
 CLADOPHORA Ktz 182 
 
 C. GLOMERATA (L.) Ktz. 
 
 pi. 50, f. 1 — S 182 
 
 CLADOPHORACEAE 182 
 
 Clathrocystis aeruginosa (Ktz.) 
 
 Henfrey 39 
 
 CLOSTERIOPSIS Lemm 136 
 
 C. LONGISSIMA v. TROPICA W. 
 
 & G. S. West pi 32, f. 8 136 
 
 COCCOGONEALES 26 
 
 COCCOMYXA Schmidle 139 
 
 COELASTREAE I 6 O 
 
 COELASTRUM Nag ] 160 
 
 C. CAMBRICUM Arch, pi, 42, f. 2 — 3 . 161 
 
 C. compositum G. S. West 162 
 
 C. MICROPORUM Nag. pi. 41, f. 
 
 12— IS; pi. 42, t. 1 160 
 
 C. PROBOSCIDEUM Bohlin pi. 42, f. 
 
 7—8; pi. 43, f. 1—2 162 
 
 C. RETICULATUM (Dang.) Senn 
 
 pi. 15, f. 9 82 
 
 C. REGULARIS (W. West) Bohlin 
 
 pi. 15, f. 16 82 
 
 CHLOROCHROMONAS Lewis 80 
 
 C. MINUTA Lewis pi. 15, f. 1—S 80 
 
 Chlorococcus regulare W West 82 
 
 CHLOROPHYCEAE 88 
 
 CHLOROSACCACEAE 81 
 
 Chodatella ciliata (Lag.) Lemm 129 
 
 V. minor G. M, Smith 129 
 
 C. citriformis Snow 130 
 
 C. DroescTieri Lemm 131 
 
 C. longiseta Lemm 130 
 
 G. subsala Lemm 130 
 
 CHROMULINALES 66 
 
 CHROOCOCCACEAE 27 
 
 CHROOCOCCUS Nag 27 
 
 C. DISPERSUS (V. Keiss.) Lemm. 
 
 pi. 1 , f. 2 28 
 
 V. MINOR G. M. Smith pi. 1, f. 3. 28 
 
 C. GIGANTEUS W. West, pi. 2, f. 1. .. 30 
 
 C. LIMNETICUS Lemm. pi. 1, t. 4- ... 29 
 
 V. CARNEUS (Chod.) Lemm. 
 
 pi. 1, f. 6 30 
 
 V. DI STANS G. M. Smith 
 
 pi. 1, f. 7 30 
 
 V. ELEGANS G. M. Smith 
 
 pi. 1, f. 8 30 
 
 V. SUBSALSUS Lemm. pi. 1, f. 5. 29 
 
 Chroococcus minor var dispersus 
 
 V. Keiss 28 
 
 pl. 42, f. 4—6 161 
 
 COELOSPHAERIUM Nag 33 
 
 C. DUBIUM Grunow pl, 3, f. 7 35 
 
 C. KUETZINGIANUM Nag, 
 
 pl. 3, f. 4—5 34 
 
 C. NAEGELIANUM Unger 
 
 pl. 3, f. 6 ; pl. .J, f. 1 35 
 
 Coenocyte 88 
 
 Cohniella staurogeniae forme SchrOder 149 
 
 Collection methods 10 
 
 Conferva echinulata J. E. Smith 63 
 
 CONJUGALES 183 
 
 CRUCIGENIA Morren 144 
 
 C. APICULATA (Lemm.) Schmidle 
 
 pl. 37, f. 1 146 
 
 C.CIRUCIFERA (Wolle) Collins 
 
 pl. 36, f. 6 145 
 
 C. FENESTRATA Schmidle pl. 37, f. 3. 148 
 C. IRREGULARIS Wille pl. 36, f. f— 5. 145 
 C. LAUTERBORNEI Schmidle 
 
 pl. .37, f. .J 148 
 
 C. QUADRATA Morren pl. 36, f. 10— 14. 147 
 
 V. punctata (Schmidle) 147 
 
 C. RECTANGULARIS (Nag.) Gay 
 
 pl. .36, f. 3 144 
 
 C. TETRAPEDIA (Kirchner) W & G. 
 
 S. West pl. 37, f. 2 147 
 
 G. triangularis (Chodat) Schmidle.... 147 
 C. TRUNCATA G. M] Smith 
 
 pl. 36, f. 7—9 146 
 
 CRUCIGENIEAE 14-3 
 
INDEX 
 
 239 
 
 Pag-e 1 
 
 DACTYLOCOCCOPSIS Hansg 47 
 
 D. ACICULARIS Lemm. pi. 6, f. 8—10 48 
 
 D. RHAPHIDIOIDES Hansg. 
 
 pi. 6, f. 7 47 
 
 DICTTOSPHAERIACEAE 104 
 
 DICTYOSPHAERIUM Nag 104 
 
 D. EHRENBERGIANUM Nag. 
 
 pi. 20, f. 11—12 105 
 
 D. PULCHELLUM Wood pi. 20, 
 
 f. 13; pi. 21, f. 1 105 
 
 DIMORPHOCOCCUS A. Br 108 
 
 D. LUNATUS A. Br. pi. 21, t. 5 106 
 
 DINOBRYON Ehr 72 
 
 D. BAVARICUM Imhof pi. 13, t. 10. . . 73 
 
 D. CALICIFORME Bachm. 
 
 Page 
 
 GLOEOTRICHIA J. G. Ag 63 
 
 I G. ECHINULATA (J. E. Smith) P. 
 
 i Richt. pi. 11, f. 5 — 6 63 
 
 ! G. visum Born, et Flah. non Thur. ... 63 
 
 iGOLENKINIA Chodat 127 
 
 I G. PAUCI SPINA W. & G. S. West 
 
 pi. 29, f. Jf—5 127 
 
 G. RADI AT A Chodat pi. 29, f. 2—3. . . 127 
 
 GOMPHOSPHAERIA Ktz 36 
 
 G. AFONINA Ktz. pi. k, t 2—3 37 
 
 V. CORDIFORMIS Wolle pi. !,, t. It 37 
 
 G. LACUSTRIS Chodat pi. 4. f. 5 36 
 
 G. Naegeliana (Unger) Lemm 35 
 
 i GONIUM Mueller 94 
 
 I G. PECTORALE Mueller 
 
 pi. 13, f. 5—6 73 
 
 D. DIVERGENS Imhof pi. 1^, f. 2 75 
 
 D. SETULARIA Ehr. pi. 13, f. 13; 
 
 V\. lit, i. 1 74 
 
 D. SOCIALE Ehr. pi. 13, f. 12 74 
 
 D. STIPITATUM Stein pi. 13, f. 11. .. . 74 
 
 D. TABELLARIAE (Lemm.) Pascher 
 
 pi. 13, f. 7 — 9 73 
 
 D. utriculus var. tabellariae Lemm. .. 73 
 
 DINOBRYONACEAE 72 
 
 ECHINOSPHAERELLA G. M. Smith 128 
 
 E. LIMNETICA G. M. Smith 
 
 pi. 29, f. 9—11 128 
 
 ECHINOSPHAERIDIUM Lemm 128 
 
 ELAKTOTHRIX Wille 139 
 
 E. GELATINOSA Wille pi. 3!,, t. 1—3 139 
 E.VIRDIS (Snow) Printz pi. S3, f. 7. 140 
 
 EUASTROPSIS Lag 174 
 
 E. RICHTERI (Schmidle) Lag. 
 
 T>1. If9, t. 3 175 
 
 Euastrum tetraodon Corda 174 
 
 EUCHROMULINACEAE 66 
 
 EUCHRYSOMONADINAE 66 
 
 EUDORINA Ehr 95 
 
 E. ELEGANS Ehr. pi. 19, /. 1 96 
 
 EUHYMENOMONADACEAE 70 
 
 Euplankton 1 
 
 Facultative plankton 1 
 
 FRANCEIA Lemm 131 
 
 F. OVALIS (Franck) Lemm. pi. 31, f. /, 131 
 
 Fusola virdis Snow 140 
 
 pi. 16, f. U — 15 
 
 Heleoplankton 
 
 Ilerposteiron hyalothecae Hansg 
 
 HETEROCHLORIDALES 
 
 IlETEROCOCCALES 
 
 Hormogones 
 
 I-IETEROKONTAE 
 
 PIETEROTRICHALES 
 
 HORMOGONEALES 
 
 Hormogones 
 
 HYALOBRYON Lauterborn 
 
 H. Lauterhornei var mucicola Lemm. 
 H. MUCICOLA (Lemm.) Pascher 
 
 pi. Ilf, f. 3 — ^ 
 
 KYDRODICTYACEAE 
 
 HYDRODICTYON Roth 
 
 H. RETICULATUM (L.) Lag. 
 
 pi. f. 6; Pl. 45, f. 1 
 
 HYDRURINEAE 
 
 Ineffigiata neglecta W. & G. S. West 
 
 ISOCHRYSIDALES 
 
 ISOKONTAE 
 
 Key to the genera 
 
 KIRCHNERIELLA Schmidle 
 
 K. aperta Teiling 
 
 K. CONTORTA (Schmidle) Bohlin 
 
 pi. 35, f. 7 
 
 K. ELONGATA G. M. Smith 
 
 pi. 36, f. 1 — 2 
 
 K. LUNARIS (Kirchner) Mobius 
 
 pi. 3//, f. 4 
 
 94 
 
 5 
 
 181 
 
 79 
 
 80 
 26 
 79 
 86 
 48 
 48 
 75 
 75 
 
 75 
 165 
 
 165 
 
 166 
 
 76 
 84 
 
 21 
 
 140 
 143 
 
 143 
 
 143 
 
 141 
 
 Gas vacuoles 33 
 
 Geography of Wisconsin 5 
 
 Geology of Wisconsin 5 
 
 GLOEOCOCCUS 102 
 
 GLOEOCYSTIS Nag 100 
 
 G. GIGAS (Ktz.) Lag. pi. 19, f. 2 101 
 
 GLOEOCYSTOPSIS G. M. Smith 102 
 
 G. LIMNETICUS G. M. Smith 
 
 pi. 20, f. 1—2 103 
 
 GLOEOTHECE Nag 45 
 
 G. LINEARIS Nag. pi. 6, f. 5 46 
 
 V. COMPOSITA G. M. Smith 
 
 V. DIANAE Bohlin pi. 34, f. 5. ... 141 
 V. IRREGULARIS G. M. Smith 
 
 pi. 35, f. i 142 
 
 K. OBESA (W. West) Schmidle 
 
 pi. 35, f. 2—3 142 
 
 V. APERTA (Teiling) Brunnthaler 
 
 pi. 35, f. 5—6 143 
 
 V. contorta Schmidle 143 
 
 V. MAJOR (Bernard) G. M. 
 
 Smith pi. 35, f. 4 142 
 
 LAGERHEIMIA Chodat 129 
 
 L. CILIATA (Lag.) Chodat 
 
 pi. 6, f. 6 46 
 
 GLOEOTAENIUM Hansg 115 
 
 G. LOITLESBERGERIANUM Hansg. 
 
 pi. 23, f. 8 — 9 115 
 
 pi. 31, f. 1 — 2 129 
 
 V. MINOR G. M. Smith pi. 31, f. 3. 129 
 L. CITRIFORMIS (Snow) G. M. 
 
 Smith pi. 30, f. 1—2 130 
 
240 
 
 INDEX 
 
 Page 
 
 L. DROESCHERI (Lemm.) Printz 
 
 pi. 30, f. 5 — 7 131 
 
 L. LONGISETA (Lemm.) Printz 
 
 pi. 30, f. 8—9 130 
 
 V. MAJOR G. M. Smith 
 
 pi. 30, f. 10 — 12 130 
 
 L. SUBSALSA Lemm. pi. 30, f. 3—1 . . 130 
 
 Lake areas of Wisconsin 6 
 
 Lakes 
 
 Altitude 6 
 
 Chemical composition of water . . 8 
 
 Formation of Wisconsin Lakes . . 5 
 
 Hard water 7 
 
 Medium water 7 
 
 Origin of Names 11 
 
 Size 5 
 
 Soft water 7 
 
 Temperature 6 
 
 Lemmermannia emarginata 
 
 Pago 
 
 M. octonarius Bailey 167 
 
 MOUGEOTIA C. A. Ag 184 
 
 M. VIRIDIS (Ktz.) Wittr. pi. 51, f. 1. 184 
 Myxonema lubricum (Dillw.) Fries... 180 
 
 MYXOPHTCEAE 26 
 
 OCHROMONADACEAE 71 
 
 OCHROMONADALES 70 
 
 OOCTSTEAE 110 
 
 Oocystella Lemm 114 
 
 OOCYSTIS Nag 110 
 
 O. BORGEI Snow pi. 22, f. Ill 
 
 O. ciliata Lag 129 
 
 O. CRASS A Wittr. pi. 22, f. 12—13 113 
 
 O. ELLIPTICA W. West pi. 22, f. 5. . . Ill 
 O. EREMOSPHAERIA G. M. Smith 
 
 pi. 23, f. 1-2 113 
 
 O. GLOEOCYSTIFORMIS Borge pi. 22, 
 
 f. 7 112 
 
 O. LACUSTRIS Chodat pi. 22, f. 8—9. 112 
 
 (Schroder) Chodat 147 
 
 Lemmermannia tetrapedia (Kirch- 
 
 ner) Lemm 148 
 
 List of Lakes studied 13-19 
 
 LYNGBYA C. A. Ag 52 
 
 L. BIRGEI G. M. Smith pi. 7, f. U — 15. 54 
 
 L. CONTORT A Lemm. pi. 7, f. 12—13. 53 
 
 L. LIMNETIC A Lemm. pi. 7, f. 9—11. 52 
 
 L. Wollei Farlow 54 
 
 L. Wollei Trelease non Farlow 54 
 
 MALLOMONADACEAE 67 
 
 MALLOMONAS Perty 67 
 
 M. ALPINA Pascher & Ruttner 
 
 O. NATANS V. MAJOR G. M. Smith 
 
 pi. 23, f. 4-5 114 
 
 O. PANDURIFORMIS v. MINOR G. 
 
 M. Smith pi. 23, f. .3 114 
 
 O. PARVA W. & G. S. West pi. 22, f. 6 112 
 
 O. PUSILLA Hansg. pi. 22, i. 3 Ill 
 
 O. SOLITARIA AVittr. pi. 22, f. 11 113 
 
 O. SUBMARINA Lag. pi. 22, f. 10 113 
 
 OPHIOCYTIACEAE 85 
 
 OPHIOCYTIUM Nag 85 ^ 
 
 O. CAPITATUM Wolle pi. 15, f. 12-13. 86 
 
 V. LONGISPINUM (Mobius) Lemm. 
 pi. 15, f. U-16 86 
 
 pi. 12, f. 4 
 
 M. CAUDATA Iwanoff pi. 12, f. 6. . . . 
 M. PRODUCTA (Zach.) Iwanoff 
 
 68 O. PARVULUM (Perty) A. Br. pi. 15, 
 
 69 t. 11 86 
 
 OSCILLATORIA Vaucher 50 
 
 pi. 12, f. 2 68 
 
 V. MARCHICA Lemm. pi. 12, f. 3. 68 
 
 M. TONSURATA Telling pi. 12, f. 5. . . 68 
 
 MERISMOFEDIA Meyen 31 
 
 M. ELEGANS A. Br. pi. 2, f. 5 32 
 
 V. MAJOR G. M. Smith pi. 2, f. 6. 32 
 
 M. GLAUCA (Ehr.) Niig. pi. 2, f. 4 ‘12 
 
 M. PUNCTATA Meyen pi. 2, f. 3 33 
 
 M. TENUISSIMA Lemm. pi. 2, f. 2. . . 33 
 
 MICRACTINIEAE 125 
 
 MICRACTINIUM Fresenius 125 
 
 M. PUSILLUM Fresenius 
 
 pi. 28, f. 1—3 125 
 
 V. ELEGANS G. M. Smith 
 
 pi. 29, f. 1 126 
 
 M. QUADRISETUM (Lemm.) G. M. 
 
 Smith pi. 28, f. 4 126 
 
 MICROCYSTIS Ktz 38 
 
 M. AERUGINOSA Ktz. pi. 5, f. 2—3. 39 
 
 V. MA.lOR (Wittr.) G. M. Smith 
 
 pi. 4, f. 6 40 
 
 M. FLOS-AQUAE (Wittr.) Kirchner 
 
 pi. .5, f. 1 39 
 
 M. ICHTHYOBLABE Ktz 38 
 
 M. INCERTA Lemm. pi. 5, f. 4 40 
 
 M. PULVERA (Wood) Migula 40 
 
 Monaciinus duodcnarius Bailey 167 
 
 O. PROLIFICA (Grev.) Gom. pi. 7, 
 
 f. 3-5 51 
 
 O. RUBESCENS D. C 51 
 
 O. TENUIS C. A. Ag. pi. 7, f. 6 52 
 
 V. TERGESTINA (Ktz.) Rab. pi. 7, 
 
 f. 7-8 52 
 
 OSCILLATORIACEAE 49 
 
 PALMELLACEAE 100 
 
 PANDORINA Bory 95 
 
 P. MORUM Bory pi. 16, f. 16-17 95 
 
 PEDIASTRUM Meyen 166 
 
 P. ARANEOSUM Racib. pi. 45, f. 11.. 168 
 
 V. RUGULOSUM (G. S. West) G. M. 
 
 Smith pi. 45, f. 12-13 168 
 
 P. BIRADIATUM Meyen pi. 48, f. 5-8 173 
 
 P. BORYANUM (Turp.) Menegh. pi. 
 
 46, f. 2-7 169 
 
 V. LONGICORNE Racib. pi. 46, f. 9. 170 
 y. longicorne forma glabrum Racib. 170 
 V. longicorne forma granulatum 
 
 Racib 170 
 
 V. UNDULATUM Wille pi. 46, f. 8. . 170 
 
 P. DUPLEX Meyen pi. 46, f. U-16 171 
 
 V. CLATHRATUM (A. Br.) Lag. 
 
 pi. 47, f. 1-3 171 
 
 V. COHAERENS Bohlin pi. 48, f. 3-4 173 
 
INDEX 
 
 241 
 
 V. GRACILLIMUM W. & G. S. West 
 
 pi. JfT, f. 8-11; pi. 172 
 
 V. RETICULATUM Lag. pi. ^7, f . 4-7 172 
 V. reticulatum forma cohaerens 
 
 (Bohl.) Brunnth 173 
 
 V. ROTUND ATUM Lucks pi. 1,6, t. 17 172 
 
 P. INTEGRUM Nag. pi. 45, f. 7 168 
 
 V. PRIVA Printz pi. 45, f. 8-10 168 
 
 P.rotula (Ehr.) A. Br 173 
 
 P. SCULPTATUM G. M. Smith pi. 46, 
 
 t. 1 169 
 
 P. SIMPLEX V. DUODENARIUM 
 
 (Bailey) Rab. pi. 45, f. 2-6 167 
 
 V. clathratum (Schroter) G. S. West 167 
 P. TETRAS (Ehr.) Ralfs pi. 48, f. 9-12 173 
 
 V. OBTUSATA Racib 174 
 
 V. TETRAODON (Corda) Hansg. 
 
 Page 
 
 Relative abundance of different species 28 
 
 RHABDODERMA Schmidle & Lauter- 
 
 born 46 
 
 R. LINEARE Schmidle & Lauterborn 
 
 pl. 6 , f. 4 47 
 
 Bhaphidium Braunii var. lacustre 
 
 Chodat 139 
 
 R. Chodati Tanner-Fullman 138 
 
 R. longissimum var. septatum Chodat 177 
 
 V. tropicum W. & G. S. West 136 
 
 B. Pfitsieri SchrOder 138 
 
 B. spirale Turner 135 
 
 RHIZOCHRYSIDINAE 77 
 
 RHIZOCHRTSIS Pascher 77 
 
 R. LIMNETIC A G. M. Smith pl. 14 , t. 6 77 
 
 R. PLANCTONICA Pascher 78 
 
 Bichteriella botryoides (Schmidle) 
 
 pl. 48, f. IS-IJ, ; pl. 1,9, t, 1-2 174 Lemm 
 
 PERONIELLA Gobi 81 I forma fenestrata Chodat 
 
 P. PLANCTONICA G. M. Smith pl. > forma tetraedrica Lemm. 
 
 15. f. 4 81 
 
 PHAEOCAPSACEAE 76 ' 
 
 PHAEOCAPSALES 76 
 
 PHAEOCOCCUS Borzi 76 ' 
 
 P. PLANCTONICUS W. & G. S. West 1 
 
 pl, 14 , f. 5 76 : 
 
 PHAEOPHYCEAE 65 
 
 Phythelois ovalis France 131 
 
 Phytoplankton 1 
 
 Pithiscus Klebsii Dangeard 93 
 
 PLANKTOSPHAERIA G. M. Smith.. 103 
 P. GELATINOSA G. M. Smith pl. 20, 
 
 f. 3-6 103 
 
 PLANOSPORACEAE 175 
 
 PLECTONEMA WOLLEI Farlow 54 ' 
 
 PLEODORINA Shaw 96 ’ 
 
 P. CALIFORNICA Shaw pl. 17, f. 1-S 97 
 
 Polycystis ichthyohlabe Ktz 88 
 
 POLYEDRIOPSIS Schmidle 124 
 
 P. SPINULOSA Schmidle pl. 27, f. 7-8 124 
 
 Polyedrium gracile Reinsch 122 
 
 P. hastatum var. palatinum Schmidle 121 
 P. lobulatum Nag 122 
 
 Bivularia echinulata J. E. Smith 
 
 RIVULARIACEAE 
 
 SCENEDESMUS Meyen 
 
 S. ABUNDANS (Kirchner) Chodat pl. 
 
 SO, f. 23-26 
 
 V. ASYMMETRICA (Schrdder) G. 
 
 M. Smith pl. 46, f. 6-8 
 
 V. BREVICAUDA G. M. Smith pl. 
 
 46, f. 3-5 
 
 V. LONGICAUDA G. M. Smith pl. 
 
 39, f. 26-27 
 
 S. ACUMINATES (Lag.) Chodat pl. 
 
 58, f. i-4 
 
 S. ACUTIFORMIS SchrOder pl. 39, f. 
 
 4-6 
 
 S. alternans Reinsch 
 
 S. ARCUATUS Lemm. pl. 58, f. 12-11,. . 
 V. CAPITATUS G. M. Smith pl. 38, 
 
 f. 15-16 
 
 V. PLATYDISCA G. M. Smith pl. 39, 
 
 f . 1 — 3 
 
 S. ARMATUS (Chodat) G. M. Smith 
 pl. 39, f . 7-10 
 
 P. muticum v. punctulatum Reinsch.. 116 
 
 P. tetraedricum Nag 118 
 
 V. hastatum Reinsch 121 
 
 P, trigonum Nag 117 
 
 V. gracile Reinsch 117 
 
 V. setigerum (Arch.) SchrOder 117 
 
 PROTOCOCCACEAE 108 i 
 
 PROTOCOCCALES 99 
 
 Protococcus mmutus Ktz 28 
 
 Pseudocilia 102 
 
 Pseudovacuoles 33 
 
 Pyrenoids 88 
 
 QUADRIGULA Printz 137 
 
 Q. CHODATI (Tanner-Fullman) G. 
 
 M. Smith pl. 35, f. 3 138 
 
 Q. LACUSTRIS (Chodat) G. M. 
 
 Smith pl. 33, f. 4-6 139 
 
 v.MAJOR G. M. Smith pl. 39, f. 11.. 
 S. BERNARDII G. M. Smith pl. 38, f. 
 
 5-9 
 
 S. BIJUGA (Turpin) Lag. pl. 37, f. 
 
 18-20 
 
 V. ALTERNANS (Reinsch) Borge 
 
 pl. 38 , f. 10-11 
 
 S. bijugatus (Turpin) Ktz 
 
 S. BRASILIENSIS Bohlin pl. 39, f. 
 
 12-14 
 
 B. caudatus Nag. non Corda 
 
 S. DENTICULATUS Lag. pl. 39, f. 
 
 17-19 
 
 S. DIMORPHUS (Turpin) Ktz. pl. 37, 
 
 f. 15-17 
 
 S. HYSTRIX Lag. pl. 39, f. 15-16 
 
 S. LONGUS Meyen pl. 39, f. 20-22 
 
 125 
 
 125 
 
 126 
 6 S 
 62 
 
 150 
 
 157 
 
 157 
 
 157 
 
 157 
 
 152 
 
 154 
 
 153 
 153 
 
 153 
 
 154 
 
 154 
 
 155 
 
 152 
 
 152 
 
 153 
 152 
 
 155 
 
 156 
 
 155 
 
 151 
 
 155 
 
 156 
 
 Q. PFITZERI (Schrdder) G. M. v. NAEGELII (Breb.) G. M. Smith 
 
 Smith pl. S3, f. 1-2 138 ; pl. 46, f. 1-2 156 
 
242 
 
 INDEX 
 
 Page ! 
 
 S. Naegeln Breb 156 
 
 S. OBLIQUUS (Turpin) Ktz. pi. 37, 
 
 f. 72-74 151 
 
 S. OPOLIENSIS P. Kichter pi. 41 , f. 
 
 8-77 159 
 
 S. QUADRICAUDA (Turpin) Breb. 
 
 pi. JfO, f. 9-11 158 
 
 V. ahundans (Kirchner) Lag 157 
 
 V. asymmetrica SchrOder 157 
 
 V. LONGISPINA (Chodat) G. M. 
 
 Smith pi. JfO, f. IS-U 159 
 
 V. MAXIMUS W. & G. S. West pi. 
 
 47 . f. 1-2 159 
 
 V. PARVUS G. M. Smith pi. J,0, f. 17 158 
 V. QUADRISPINA (Chodat) G. M. 
 
 Smith pi. 40 . f. 15-16 158 
 
 V. setosus ( Kirchner ■> Lag 156 
 
 V. WESTII G. M. Smith pi. 47, f. 
 
 5-7 159 
 
 SCHROEDERIA Lemm 136 
 
 S. JUDATI G. M. Smith pi. 52, f. 9-11 137 
 S. SETIGERA (SchrOder) Lemm. pi. 
 
 52, f. 72 137 
 
 SELENASTREAE 132 
 
 SELENASTRUM Relnsch 132 
 
 S. acuminatum G. S. West non Lag. 133 
 
 8. acuminatum Lag 152 
 
 S. BIBRAIANUM Reinsch 
 
 Page 
 
 TETRADESMUS G. M. Smith 150 
 
 T. WISCONSINENSIS G. M. Smith 
 
 pi. 57, f. 7—11 150 
 
 TETRAEDREAE I 15 
 
 TETRAEDRON Ktz II 5 
 
 T. arthrodesmiforme v. lohulatum 
 
 Wolosz 122 
 
 T. CAUDATUM (Corda) Hansg. 
 
 pi. 25, f. 4 — 7 120 
 
 V. LONGISPINUM Lemm. pi. 25, 
 
 f. 8-12 120 
 
 T. CONSTRICTUM G. M. Smith 
 
 pi. 25, f. 22—24 122 
 
 T. ENORME (Ralfs) Hansg. pi. 27, t. 6. 124 
 T. GRACILE (Reinsch) Hansg. 
 
 pi. 25, f. 7 — 5 122 
 
 T. HASTATUM (Reinsch) Hansg. 
 
 pi. 25, f. 78 121 
 
 V. PALATINUM (Schmidle) 
 
 Lemm. pi. 25, f. 19—21 121 
 
 T. LIMNETICUM Borge pi 27, f. 7—5. 123 
 T. LOBULATUM (Nag.) Hansg. 
 
 pi. 26, f. 6—7 122 
 
 V. POLTFURCATUM G. M. 
 
 Smith pi. 26, £. 8 123 
 
 T. MINIMUM (A. Br.) Hansg. 
 
 pi. 24 , f. 10— IS 118 
 
 T. MUTICUM V. FUNCTULATUM 
 
 pi. 57, f. 6 — 7 
 
 S. GRACILE Reinsch pi. 57, f. 5 
 
 S. WESTII G. M. Smith pi. 37, f. 8—10 
 Selenosphaerium americanum Bohlin. 
 
 SIPHONOCLADIALES 
 
 SORASTRUM Ktz 
 
 S. AMERICANUM (Bohlin) Schmidle 
 
 pl. 44, f. 7 
 
 UNDULATUM G. M. Smith 
 
 pi. 44 , f. 2—5 
 
 S. SPINULOSUM Nag. pi. 44, f. 4—5. 
 
 SPHAEROCTSTIS Chodat 
 
 S. SCHOETERI Chodat pi. 19, f. 3—4. 
 
 SPIROGYRA Link 
 
 S. PORTICALIS (Mueller) Cleve 
 
 pi. 51, f. 3 
 
 SPIRULINA Turpin 
 
 S. MAJOR Ktz. pi. 7, f. 7 
 
 S. FRINCEPS (W. & G. S. West) 
 
 G. S. West pi. 7, £. 2 
 
 Staurogenia apiculata Lemm 
 
 8. cruciatum Wolle 
 
 8. crucifera Wolle 
 
 8. fenestrata Schmidle 
 
 8. Lauterhomei Schmidle 
 
 8. multiseta v. punctata Schmidle . . . 
 
 8. tetrapedia Kirchner 
 
 8. triangularis Chodat 
 
 STIGEOCLONIUM Ktz 
 
 S. LUBRICUM (Dillwyn) Ktz. 
 
 pi. 50, £. 7 
 
 SYNURA Ehr 
 
 S. UVELLA Ehr. pi. 12, f. 9—10 
 
 Tetracoccus botryoides W. West 
 
 133 
 
 133 
 
 133 
 
 163 
 
 182 
 
 162 
 
 163 
 
 163 
 
 163 
 
 101 
 
 101 
 
 185 
 
 185 
 
 49 
 
 50 
 
 50 
 
 146 
 145 
 145 
 148 
 148 
 
 147 
 147 
 147 
 180 
 
 180 
 
 70 
 
 120 
 
 121 
 
 123 
 
 (Reinsch) de Toni pi. 23, f. 10—13. 116 
 T. PENTAERUICUM W. & G. S. 
 
 West pi. 25, f. 75—77 
 
 V. minimum W. & G. S. West 
 T. PLANCTONICUM G. M. Smith 
 
 pi. 27, f. 4—5 
 
 r. proteiforme G. M. Smith non (Turn.) 
 
 Brunnthaler 
 
 T. REGULARE Ktz. pi. 24, f. 74 H8 
 
 T. regulare Chodat non Ktz 119 
 
 V. INCUS Telling pi. 24, f. 15—76. 118 
 V. TORSUM (Turner) Brunn- 
 thaler pi. 24, f. 77—78 119 
 
 T. spinulosum Schmidle 124 
 
 T. TRIGONUM (Nag.) Hansg. 
 
 pi. 23, f. 74 — 16 117 
 
 V. GRACILE (Reinsch) de Toni 
 
 pi. 24 , f. 5—9 117 
 
 V. SETIGERUM (Archer) Lemm. 
 
 pi. 24 , f. 7—4 117 
 
 T. VERRUCOSUM G. M. Smith 
 
 pi. 25, f. 2—3 
 
 T. VICTORIEAE Wolos 
 
 V. MAJOR G. M. Smith pi. 24, 
 
 f. 79 — 22; pi. 25, f. 7 H9 
 
 Tetrapedia emarginata SchrOder 147 
 
 T. pentaedricum Chodat 129 
 
 T. setigera Archer H7 
 
 TETRASPORA Link 192 
 
 T. LACUSTRIS Lemm. pi. 79, f. 5 — 6 . 102 
 
 TETRASTRUM Chodat 149 
 
 70 jr. wpiculatum (Lemm.) Brunnthaler. . 146 
 197 T. mwZtisetwm (Schmidle) Chodat ....147 
 
 119 
 
 119 
 
INDEX 
 
 243 
 
 Page 
 
 T. STAUROGENIAEFORME 
 
 (Schroder) Lemm. pi. S7^ f. 5 — 6. 149 
 
 TRICHODESMIUM Ehr 64 
 
 T. LACUSTRE Klebahn pi. 8, f. 1 54 
 
 TRIBONEMA Derbes et Sober 87 
 
 T. BOMBYCINA v. DEPAUPERATA 
 
 Wille 87 
 
 T. MINUS (Wille) Hazen 
 
 pi. 15, f. n — 18 87 
 
 TRIBONEMACEAE 87 
 
 Triehomes 48 
 
 TROCHISCIA Ktz 108 
 
 T. RETICULARIS (Reinsch) Hansg. 
 
 pi. 22, f. 2 109 
 
 Tychoplankton 1 
 
 ULOTRICHACEAE 178 
 
 ULTRICHALES 178 
 
 ULOTHRIX Ktz 179 
 
 U. SUBCONSTRICTA G. S. West 
 
 pi. 50, f. -J— 5 179 
 
 U. ZONATA (Weber & Mohr) Ktz. 
 
 pi. 50, f. 6 179 
 
 Page 
 
 XJroglena americana Calkins 71 
 
 UROGLENOPSIS Lemm 71 
 
 U. AMERICANA (Calkins) Lemm. 
 
 pi. 18, f. 1—4 71 
 
 VOLVOCACEAE 93 
 
 VOLVOCALES 89 
 
 VOLVOX L 97 
 
 V. AUREUS Ehr. pi. 18, f. 2 98 
 
 V. GLOBATOR L. pi. 18, f. 3—5 98 
 
 V. lMONONAE G. M. Smith, pi. 18, f. 1 99 
 
 WESTELLA de Wildeman 106 
 
 W. BOTRYOIDES (W. West) de 
 
 Wildeman pi. 21, f. ^ 107 
 
 V. MAJOR G. M. Smith 107 
 
 W. LINEARIS G. M. Smith 
 
 pi. 21, f. 2—3 107 
 
 Zooplankton 1 
 
 ZYGNEMA C. A. Ag 184 
 
 Z. PECTINATUM (Vaucher) C. A. 
 
 Ag. pi. 51, f. 2 185 
 
 ZYGNEMACEAE 183