+ —+ =o —0-¢-# — ~e— eo rer ee) +e ipssisayi wuevinae Foye as amine aca ye rer ert yur rare Utes ea 9 — ¢—0—0 oe eee eer rar pees ne Otto Savarese
brsesonrawabapanae cece co AS SPE e tr Shc ater DOS SS se Panes coer et Pare E RE er aoa een eet ae Paneer T Eras tan ey eee ei atet Spite ty rar sap sy seas yyw ay rar isieta > etctats 7 pietes Pagar ea ins padi rare pagans ee rey iets etary etets et at OT ae epee eee eg arent tee Peeper ae ete tetetenetetetes ka! tenet 3 ees ees eeetitetetntesetetates st th ieararansearawea geese eae wapaety aeSrae ag Puie tenes rirR Pah riya eeee parersorne pereeeee soahivarabarsra ss pense ene nrg rene nes aire ere rataterir she Fp eet tet 5 Piva ne mskne raw wird 4. INP RN PA eae. Se ere mere eer re See iibsbabsrabes coer : eavarararass “iragerpries fares retertrs tetra te etree Sa peta tane nee 2250 = =i Tate Cpt frtrt, tp tates pa: ett ttitate eet Introduction Although convenient, the term algae has been applied to such a great variety of plant groups and has been given so many interpreta- tions that it has no very precise meaning. In the broadest sense it may refer to all chlorophyll-bearing thallophytes and protista, and their colorless close relatives. Life history studies have established genetic relationships between definitely plant-like and animal-like algae. Thus the incorporation of the Volvocales in the phylogeny of the Chlorophyta is necessary. Other protozoa-like, pigmented organisms, such as the Euglenophyta and the Cryptophyceae and other Pyrrhophyta, are examples of evolutionary lines which appar- ently have ended blindly in their present expressions. One might contend, therefore, that their inclusion among the other definitely plant-like algae cannot be justified because, unlike the Volvocales, they have no phylogenetic connections with the group. Notwith- standing the fact that the Euglenophyta and Pyrrhophyta include some colorless and definitely protozoa-like relatives, the groups merit a place in phycological study by virtue of their many plant-like at- tributes. Likewise, chlorophyll-bearing, bacteria-like organisms must be given a place in the broad definition of the Cyanophyta. Many of the organisms belonging to the Chrysophyta have only a few char- acteristics which entitle them to a place among the algae, but be- cause the morphology and the habits of some members are funda- mentally plant-like their inclusion is clearly justified. Whatever limits of classification may be set up for the algae, all these groups of simple organisms are interesting to the phycologist, the aquatic biologist, the limnologist, and the oceanographer. In order to meet a number of these interests and to make the present work as useful as possible, the broader interpretation of the algae has been adopted and representatives from the eight divisions are treated here. (There are eight divisions, or phyla, if one recognizes the Chloromonadineae. This little-known class is represented by Gonyostomum semen Dies. in our collections.) Hardly any two phy- cologists are in complete agreement on the disposition of forms with- in the algal groups. The taxonomist will note, therefore, many inconsistencies if the details of the arrangement used here are com- pared with any one of the several schemes followed in handbooks, [1] floras, and in some monographic works. I have chosen to use familiar names of long standing unless changes in such names have been adopted in generally used monographic studies which are easily obtainable for reference. For the most part I have followed the taxo- nomy and nomenclature suggested by Pascher (1931) and employed by Gilbert M. Smith (1938). The structure of the cell wall, the pig- mentation, and the nature of food reserves have been used to unite the Heterokontae, the Chrysophyceae, and the Bacillariophyceae to form what seems to be a very natural division, the Chrysophyta. This rearrangement reduces the number of groups previously recog- nized among the algae. The colorless relatives of the motile algae are not included here. The taxonomic arrangement employed, then, takes the following plan: Division I. Chlorophyta (Green Algae) A. Chlorophyceae B. Charophyceae Division II. Chrysophyta (Yellow-green Algae ) A. Xanthophyceae (Heterokontae ) B. Chrysophyceae C. Bacillariophyceae (Diatoms ) Division IJ. | Euglenophyta (Euglenoids ) Division IV. | Chloromonadophyta (Chloromonads ) Division V. Pyrrhophyta (Yellow-brown Algae ) A. Cryptophyceae B. Desmokontae C. Dinophyceae Division VI. | Phaeophyta (Brown Algae, marine ) Division VII. | Cyanophyta (Blue-green Algae) A. Myxophyceae B. Chlorobacteriaceae Division VIII. Rhodophyta (Red Algae, mostly marine) In the following pages certain terms will be used frequently when reference is made to the type of existence most characteristic of a species. The name plankton, of course, refers to organisms which [2] have a drifting habit and includes all forms of both macro- and microscopic life which float free in the water or, if motile, are un- able to swim against currents. Open-water plankters are called euplankton (true plankton). Many algal species existing as such have elongations of the cell, or bear long spines, whereas others may gain buoyancy through the possession of mucilage. There is evidence that pseudovacuoles in the cells of many blue-green plankters aid in this connection. Forms which are unattached but are caught among filamentous algae and other vegetation and reproduce in shallow water are called tychoplankton. The minute phytoplankters which pass through the meshes of a fine (No. 20) bolting-cloth collecting net are here termed nannoplankton. A special term, periphyton, may be applied to the organisms which form associations on the stems and leaves of aquatic plants. Benthic algae, benthos, are the organ- isms which live on the bottom especially in deep water, for ex- ample, Chara, Nitella, Dichotomosiphon, and some species of Cladophora. [3] Geological Features and Algal Distribution Some species of aquatic plants may have a wider geographical dis- tribution than terrestrial forms. This is true, for the most part, because of the more nearly universal similarity of aquatic habitats and the somewhat greater constancy of the factors which play a role in determining distribution. It need only be mentioned, by way of illustration, that in an aquatic habitat nutrients are more equally diffused and more readily obtained, temperature changes more gradual, and annual temperature range less, than in a terrestrial environment. Ecologists, however, not infrequently assume a more universal distribution for aquatics than may actually exist; in a recent excel- lent volume on ecology one finds a complete disregard of plants in an aquatic environment. Facts bear out the reasonable assumption that habitats with similar floras have the necessary determining physical-chemical conditions in common. Where there are variations in the flora and when there is an absence of widely distributed species from certain habitats, correlated modifications in the environ- mental factors, sometimes obscure, must be sought for. As is well known, species are subject in their distribution, in water as on land, to limitations imposed by the presence or absence of certain ecologi- cal factors. Less than minimal requirements of salts, carbon dioxide, nitrogen, phosphorus or other nutrients, the degree of illumination, and temperature changes are a few of the factors involved in distri- bution and habitat selection. The part ecological factors play in determining quantity and qual- ity of algal floras is readily appreciated in a study of lakes in this area, famous for its great number of inland bodies of water, bogs, and forested swamps. In Michigan there are about 11,000 lakes, with a total area of 1137.6 sq. mi.; Antrim County has 10.1 per cent of its area in lakes, and several other counties have nearly as much (Brown, 1943). In Vilas County, Wisconsin, the area occupied by lakes is 15 per cent of the total, although this figure does not include the innumerable small ponds, permanent pools, and _ spring-like seeps where algae abound. It is estimated (Juday, 1914, p. xi) that [4] approximately 1620 sq. mi. of Wisconsin are water, as compared with 55,256 sq. mi. of land surface. The suitability for algae of this entire lake region is reflected in its rich and heterogeneous aquatic flora. The great variety of aquatic habitats makes it possible to relate certain species or complexes of species to what may be called ‘types’ of lakes. In making such a correlation it is of course necessary to rec- ognize that it is practically impossible to ‘type’ a lake, because each one, in final analysis, possesses a distinct individuality. It is possible, however, to classify lakes according to certain characteristics which are of known biological significance. Most lakes in the region are of glacial origin, but because geographical and geological features (and the geological history) are not uniform there are some general differences to be noted in the bodies of water occupying respective sections. For the surface features and geology of Michigan the reader is referred to Leverett (1911, 1917). The pertinent geological features of Wisconsin have been ade- quately described by G. M. Smith (1920), and the reader is urged to refer to the highly informative introduction to his volume, “Phyto- plankton of the Inland Lakes of Wisconsin, Part I.” In this connec- tion also see the remarks on p. 8 et seq., of this volume. SOIL TYPES AND ALGAL DISTRIBUTION MICHIGAN The physiography within the political boundaries of Michigan is extremely varied and is in part complicated by the differences in the geology of the Upper and Lower Peninsulas. The Upper Peninsula, lying between Lake Superior on the north and Lake Michigan on the south, is about 300 miles long, east and west, and averages about 50 miles in width. The Upper Peninsula itself has two definite areas the character of which is determined by the type of underlying rock formation. One, west of a north-south line passing through Mar- quette, is a highland region which continues on over into northern Wisconsin (to be discussed below), where it is referred to as the High- land Lake Region. This is underlain by ancient rock formations (Pro- terozoic) which are covered in most places by glacial drift; notable exceptions, of course, are the Porcupine Mountains in the far western part of the Upper Peninsula, and hard ‘knobs’ also project elsewhere. The basic rock is both sedimentary and igneous. These crystalline masses seem to have exerted an influence on water chemistry in certain sections of this western half of the Peninsula, especially in those sections where the rock is exposed or covered [5] by only a thin mantle of glacial deposits. In general, the lakes of the region are characteristically soft or semi-hard and are poor pro- ducers of phytoplankton bulk. It is well known that waters associ- ated with pre-Paleozoic rock are low in calcium, are usually but little mineralized, and support a predominantly desmid flora, especi- ally in habitats that possess a low pH. (The symbol pH refers to the relative amount of free hydrogen ions in a solution. Soft water or acid lakes have a pH below the neutral point, pH 7.0, whereas hard water lakes give readings above neutral, pH 7.1-9.8.) Such algal col- lections as have been made in northwest Michigan, and in the same topography of northern Wisconsin, bear out this relationship. The moraines and drifts of sand left by the recession of the last glacial lobes are largely responsible for the numerous soft water lakes and acid swamps that are especially abundant north of Michigamme, in Michigan, and in upper Wisconsin. The phytoplankton and the desmid flora are characteristic of soft water lakes in the western section, whereas in the second area, which forms the eastern part of the Upper Peninsula, the flora is, in general, that of semi-hard water habitats. This is in accord with the geology of the area, which is underlain by younger Paleozoic rock, all sedi- mentary and unmetamorphosed. The eastern section is known as the Lowlands because the greatest altitude (with possible exceptions ) is only 250 feet above lake level. Shale and limestone predominate, the latter forming a tableland along the northern border of the present Lake Michigan. The Lowlands swing back westward both north and south of the western Highlands into Minnesota and Wisconsin. There are numerous outcroppings, and the effect on water chemistry is marked, finding expression in lakes with a pH generally higher than that of the western lakes. Like the western province, the eastern region has been covered by glacial drift that came in with the ice from northeast Canada, resulting in extensive swamps and sluggish streams. Whereas there are some habitats (such as an occasional acid swamp ) that develop a rich algal flora, most of the waters in the eastern area are not good producers, and the flora is strangely poor in both bulk and number of species. Many of the slow-flowing streams of the area are practically barren, and such algal forms as are conspicuous are cyanophycean or hard water chlorophycean (Phormidium, Oscillatoria, Spirogyra, Chara). The darkly stained water of the Tahquamenon River, however, is characterized by a luxuriant growth of Nitella, a genus almost always confined to soft water or water rich in humic acids. Big Spring, near Manistique, Michigan, is an interesting habitat with an algal flora that seems typical of the region. The spring has [6] a tremendous flow of water that forms a deep pool and is the fount for a large stream. The pool is clear, the water hard, and there is a luxuriant growth of Chara over much of the bottom. There is also a scant development of Spirogyra spp. along the fringes of the pool, while Oscillatoria spp. and Phormidium spp. encrust sub- merged timbers and water-logged wood. The pool is bordered in part by the vestige of a tamarack swamp, bedded with Sphagnum. The water here is only slightly acid, and the algal flora in the swamp is not rich in desmids as might be expected but very meager and consists mostly of filamentous Zygnemataceae characteristic of hard or semi-hard water situations. In the Lower Peninsula of Michigan, which is also underlain by Paleozoic rock, there are five physiographic regions. The most northern one, the Northern Upland, occupies roughly the upper quarter of the Peninsula and is bordered on the south by a diagonal line running northeast-southwest from Alpena toward Muskegon on the west coast. The line swings north, however, before reaching Muskegon and extends to the lake, passing up and around Man- istee. The Northern Upland is characteristically a semi-hard and soft water lake region; although some bodies are basic (pH 7.8, for example) most of them are below pH 7.1 and some as low as pH 4.2. Except for a few limestone exposures the region is deeply covered with a sandy glacial drift which has formed innumerable lakes and swamps. The result is that the algal flora is richer and more varied than perhaps anywhere else in the state. There are both acid swamps favoring a luxuriant desmid and Oedogonium flora, and mineralized waters supporting a characteristic flora in which planktonic blue-green algae predominate. Meager water blooms develop in a few lakes of upper Michigan, which are alka- line, which have an ample supply of carbon dioxide, and which have been fertilized by nitrogenous matter from tilled soil or from human habitation. Such conditions are more common in the south- ern part of the state, where water is harder and where the lakes are frequently the eutrophic type. Southwest from the Northern Upland is the Michigan Lowland, bordering Lake Michigan. To the southeast is first the Saginaw Lowland, extending southwest from Saginaw Bay of Lake Huron, then the Thumb Upland, including the ‘Thumb’ and the greater part of central southern Michigan. In the Thumb Upland, hard waters predominate and although there is an occasional kettlehole type of tamarack swamp, most of the water is rich in calcium, and the hard water (cyanophyte-diatom) flora prevails. Many lakes are bedded with Chara, and numerous marl deposits are found in old [7] lake bottoms of southern Michigan. The marl lakes are character- istically poor in both plankton and higher vegetations ( Potamoge- ton, Ceratophyllum, Myriophyllum). In such hard water lakes, however, where nitrogenous substances and phosphorus are pres- ent, higher aquatic plants become so abundant as to cause serious problems. The few collections that have been made from the Erie Low- lands (including the Detroit area and the extreme southeast of Michigan ) show that here too the algal flora, like that of southern Wisconsin and Minnesota, is characteristically the hard water type. WISCONSIN The geological history of this state has determined six general soil areas which are shown in F igure 1. Except for the unglaciated limestone in the driftless area of the southwest corner of Wisconsin, the soils represent deposits from the various periods of glaciation. They overlie three chief types of basic rock formation shown in Figure 2: crystalline rock in the northern third of the state; lime- stone in the southern third and extending into the Green Bay region; a sandstone area in the middle portion of the state and the extreme northwestern corner. These soil types, in combination with their respective underlying rock formations, determine four great areas of the state, which, generally speaking, show corresponding differences in lake types and algal floras. First, there is a glaciated limestone region, the northern bound- ary of which extends diagonally east to west, beginning just above Green Bay in Marinette and Oconto counties and ending with Green County in the south-central part of the state. This highly calcareous area occupies most of the southeastern third of Wiscon- sin. Second, there is an unglaciated limestone area made up of six- teen southwestern and western boundary counties. Because this is a driftless area there are few lakes in the region. As would be expect- ed, the lakes in the entire lower portion of the state, both southeast and south-central, are rich in calcium, magnesium, carbonates, and bicarbonates. These qualities, together with such factors as relative shallowness and high summer temperatures, determine the character of the algal flora which, in general, is the cyanophyte- diatom, or hard water type. In Lauderdale Lake, Walworth County, Wisconsin, for example, the number of species of Chlorophyta and Cyanophyta are about equal, but the abundance of the latter far exceeds the bulk of the green algal vegetation. This is in keeping with the general observa- tion that where water is warm, rich in fixed and half-bound carbon [8] === RED CLAY b 1+ GRANITE b ‘ HEAVY SILTLOAM SC SS SANDY Rae Sizes \_| Se GLACIATED LIMESTONE a ee ES SSE Xl ~..| os UNGLACIATED LIMESTONE = SS as Ee an ho RSS aati n eee Saae" {ILE Es 0B Pea SSS. Sas = Figure 1. Distribution of the chief soil types in Wisconsin. The unglaciated limestone region of the southwest is practically devoid of lakes. In the granite and sandy soils of the northern half of the state, the lakes are mostly soft water, and there are many acid bogs. In the central and southeast portion of the state, the lakes are basic (hard water). (Soil data from the Wisconsin Geological and Natural History Survey. Base map courtesy of A. J. Nystrom and Co. ) [9] linn y LU IH i >A ep A ac tha pr > red: Tie et s ae Ws Sereatane Es DB Se Tire On aS bos a= Care) gical an in Geolo Figure 2. Distribution of three underl (Data from the Wiscons courtesy of A. J. Nystrom and Co.) [ 10 } dioxide, and high in nitrogen, cyanophycean and diatom species predominate, both in number of kinds (usually), and number of individuals. In the lakes which characterize this calcareous region, blue-green algal water blooms develop during summer periods. The water chemistry is reflected in the flora of the Green Bay and Fox River area, where the phytoplankton is made up almost en- tirely of Microcystis aeruginosa, Aphanizomenon flos-aquae, Lyng- bya Birgei, Stephanodiscus niagarae Ehrenb., and Melosira spp., with infrequent specimens of Pediastrum Boryanum, P. duplex, and Dinobryon sertularia. The Fox and East rivers drain a calcareous and clay soil region, gathering considerable quantities of waste from agricultural lands and industrial plants. Williamson e¢ al. (1939, p- 66) have expressed the opinion that a heavy bloom of blue-green algae in these waters is not related to the nitrogen content, but nitrogen in available form for plants is relatively abundant in these streams, especially as compared with that in inland lakes. Bound carbon dioxide is likewise relatively abundant. Such fea- tures are usually correlated with luxuriant cyanophyte—diatom floras (see Sawyer, Lackey, and Lenz, 1943). In lakes that have a chemistry similar to the Fox and East Rivers the number of blue- green algal individuals may reach several million per liter. Lake Geneva, Walworth County, Wisconsin, is another hard water lake 1n the glaciated limestone soil area which is larger and deeper than Lauderdale Lake. It is high in carbonates (74 ppm), calcium (20.7 ppm), magnesium (26.9 ppm), sodium (4.4 ppm), and HCO (110.5 ppm). Analyses of Lake Geneva water samples made in August 1940 show a relatively high nitrogen content: organic nitro- gen 0.55 ppm, ammonia 0.01 ppm, nitrate nitrogen 0.8 ppm, nitrites 0.0. As might be expected, the phytoplankton of this lake is predom- inantly blue-green. Microcystis aeruginosa, Coelosphaerium Naegeli- anum, and Lyngbya Birgei being the most conspicuous represent- atives. The green algae which occur here in June, for example, are Cladophora fracta and C. glomerata, species typical of hard water habitats. In contrast, the desmid and predominantly chlorophycean flora appears not to occur in the lakes of this limestone region. There is further discussion of hard water lakes below. The third and fourth soil types, which are much less clearly de- fined, constitute, in general, the upper third of the state. This is basically a crystalline rock area, but within it are sandy soils and glaciated granite soils. The former predominate in the north-central] counties: Vilas; Oneida, parts of Langlade, Lincoln, Forest, Iron, and Price. The same soil appears in the central part of the state in a sandstone region including Juneau, Adams, and Monroe counties, [11] and there appear to be other sandy islands in the northwestern and northeastern corners of the state. The glaciated granite soils lie over crystalline rock areas both east and west of the north- central sandy soil region. Too few lakes have been sampled in northwestern Wisconsin to make it possible to generalize on the relative quality and quantity of the algal flora. Such limnological data as have been collected by Birge and Juday indicate that there are fewer soft water lakes in the northwest than in the north-central and eastern sections of Wisconsin. In Washburn County there is an extensive sand hill area in which the lakes are characteristically soft water. Here there was the expected paucity of algae, especially of phytoplankton. An interesting situation exists in the Waupaca chain of lakes in Waupaca County, where there are glaciated granite soils, but also crystalline rock and sandstone, with small amounts of surface lime- stone in the extreme southeast (Whitson, Geib, and Tosterud, 1921). The glaciated granite soils extend up into the northeast sec- tion of the state, and there is a great area of similar soils in the northwest. Most lakes in this type of soil are soft water, with typical soft water algal floras. In many of the Waupaca lakes, however, the water is so exceedingly hard that lime incrustations form on stones and submerged objects of all kinds. Similar conditions occur in some south-central Michigan lakes. The floras are typical hard water types. Chara spp., heavily incrusted with lime, abound in many lakes. The explanation of these hard water lakes in the sand- stone and granite soils of Waupaca County is found in the geologi- cal history of the area. Among the glacial soils brought into this part of the state from the east there was a considerable amount of dolomite, the outwash from which is highly calcareous. Hence, lakes in the Waupaca chain are characterized by hard water floras. A greater part of the limnological work in Wisconsin has been done in the granite and sandy soil areas of the northeast and north- west sections. Accordingly more attention was given the highland lake areas when the present survey was made, in order to make correlations possible between types of floras and physical-chemical data. In the entire northern portion of the state the lakes are char- acteristically soft, poor in calcium, low in half-bound carbon diox- ide and nitrogen, and give pH readings on the acid side of neu- trality. A soft water lake might have 9.8 mg. or less of bound carbon dioxide per liter, whereas in a hard water lake there might be 43 mg. or more per liter. It is in such soft water lakes of northern Michigan and Wisconsin that finely drawn differences can be noted in algal ecology. [12] For although most of the lakes are soft, those which do have a somewhat alkaline or basic character reflect their chemistry in a noticeably richer blue-green and diatom flora. In Arbor Vitae Lake, Wisconsin, for example, a lake somewhat harder than nearby Trout Lake, a relatively heavy bloom of Gloeotrichia echinulata is sup- ported, and the flora as a whole is the cyanophyte—diatom type. A comparison of the algal flora of the northern and northeastern sections with those of the south and southeastern sections of both Michigan and Wisconsin leads to the generalization that in the northern sections the bulk of the algal vegetation is low but the number of species is high. The larger number of species for the northern section is due to the luxuriant desmid flora which abounds in the soft (acid) water lakes and bogs. (See Fassett, 1930; Wilson, 1937, 1941, on the larger aquatic plants of lakes in northeastern Wisconsin. ) Approximately 200 collections were made from the sandy-crystal- line rock area of northwest Wisconsin (Burnett, Washburn, and Sawyer counties). The lakes here, as has been pointed out, are mostly soft water, with a pH on the acid side. The bottoms and the shores are sandy, with little aquatic vegetation of any kind. Of course there are exceptions. Shell Lake in Washburn County, for example, is a habitat of relatively hard water, supporting a rich blue-green algal flora. This is the only lake in northern Wisconsin from which collections were made that had a bloom of Aphani- zomenon flos-aquae. Although chemical analyses are not at hand for support, one can predict that this lake is relatively rich in nitro- gen, as judged by the cyanophyte-diatom flora. This condition might be expected because the lake lies within the town of Shell Lake and is bordered, in part, by tilled soil, a situation which makes the accumulation of nitrogenous substances possible. In contrast is Round Lake, Sawyer County, a large lake with a considerable amount of shallow water which supports a very scant phytoplank- tonic flora, with filamentous forms poorly represented. Chara spp., at least when collections were made in August, were found to be stunted. There were, however, luxuriant beds of Nitella, a genus which prefers soft water habitats. LAKE TYPES AND ALGAL DISTRIBUTION Inland lakes of the region fall naturally into four main types as determined by hydrographic features. In their Wisconsin lake surveys Birge and Juday noted and described significant limnologi- cal characteristics peculiar to these classes. Correspondingly, the [13 ] production of plant and animal life, as might be expected, is found to vary when the biotas of the respective types of lakes are com- pared. The chief types are: 1) hard water drainage lakes, stream or spring-fed, with an outlet, at least during part of the year; 2) hard water seepage lakes (rare), high in calcium, magnesium, and half-bound carbon dioxide, landlocked; 3) soft water drainage lakes (uncommon in Wisconsin and Michigan), low in calcium and half-bound carbon dioxide, with inlet and outlet; 4) soft water seepage lakes (common, particularly in northern parts of the area, in the northern part of the Lower Peninsula, the Upper Peninsula of Michigan, and in upper Wisconsin), low in calcium, magnesium, and half-bound carbon dioxide, fed by seepage or drainage from bogs, without outlet. To these four classes, two other types of lakes should be added: 5) acid bog lakes, mostly seepage, low in calcium; 6) alkaline bog lakes, mostly drainage, relatively high in calcium. In general, the lake types are determined by differences in their geological history, differences principally related to glaciation. The most recent glaciation, Late Wisconsin, obviously had the greatest influence on the present physiography of the region. Although most lakes had their birth during and following the closing years of this period, it appears likely that a few of the deeper lakes, Lake Geneva and Green Lake in Wisconsin, for example, may antedate the Late Wisconsin. There are at least four types of lake formation in the Great Lakes region: 1) depressions formed by the melting away of great blocks of glacier fragments and the subsequent sloughing off of glacial drift so that mounds of debris were left about a kettle- hole, which is usually soft and is frequently the acid bog type; 2) lake basins formed by the damming of preglacial valleys; 3) basins created when terminal moraines were formed in parallel ridges and the intervening valleys dammed subsequently by deposits at either end; and 4) depressions formed in the ground moraine. (See Juday, 1914. ) The lakes which were left with an outlet became immediately a part of a drainage system Other drainage systems were evolved by subsequent wearing away of impounding glacial deposits and through variations in water level. Thus some lakes were included in a drainage system, but others were left perpetually land-locked and doomed consequently to extinction. Fundamental differences between the drainage and seepage types of lakes, which are so con- spicuous today, are related, therefore, to the mode of the lakes’ for- mation in the remote past. [14 ] Harp WATER DRAINAGE LAKES These lakes are numerous and are to be found in such drainage systems as the Wisconsin River, the St. Croix River, the Fox River, and the Yahara River in Wisconsin, and in the Crooked River and Cheboygan River in Michigan. In general, they are high in calcium and half-bound carbon dioxide (see Table 1) and correspondingly have a high pH (pH 7.2-9.4). Reference has already been made to this type of lake and its characteristics. In southern Michigan and Wisconsin, most drainage lakes are naturally harder than in the northern parts of the states because of the difference in the chemis- try of the soil. It is noteworthy that when the drainage type of lake in the highland region has a sandy bottom, and few flat beaches or shallow bays, it may be as poor a producer as some of the soft water lakes. In Table 1, 13 hard water drainage lakes are listed to show something of the quality of their algal floras in relation to critical limnological features. Compare Table 1 with Table 2, which summarizes collections made in Wisconsin from December through July. These general quantitative and qualitative observations contribute to the evaluation of the hard water lake as an habitual producer of blue-green and diatom floras which are rich both in number of spe- cies and in number of individuals. Chlorophycean species, on the other hand, while not always fewer in number than the components of the cyanophyte-diatom flora, comprise but a small portion of the bulk of algal vegetation in hard water lakes. Except for the Volvo- cales, they seldom, if ever, form water blooms. Certain members of the Volvocales, Volvox and Pandorina, in some lakes may reach cli- maxes that form blooms, though of relatively short duration. Drainage prevents hard water lakes from achieving a constantly high concentration of nutrients; yet the chemistry of the water, together with such eutrophic features as shallowness and high sum- mer temperatures, make possible the characteristic luxuriant flora. This type of lake may also have a high productivity of larger aqua- tic vegetation—Sweeny Lake in Oneida County and Lake Mendota in Dane County, Wisconsin, and Ocqueoc Lake in Presque Isle County, Michigan, for example. Although there is conflicting evidence regarding the role that phosphorus plays as a controlling factor in the development of aquatic floras, many critical studies indicate that it is a regulator. It is well known that soluble phosphorus in a lake decreases with the seasonal increment in plankton and increases as organisms die and disintegrate. Tressler and Domogalla (1981) have shown that in Lake Wingra (Wisconsin) soluble phosphorus declines and [15] ‘QouyINS OY) JV pur yap srajyatu g Je UBAIB 9IV LIBULAL AYVY IOJ *7OHD JO sdurpvay ‘uot sad syed = wdd ‘sJUNOD AATYSNUYXe JUesaIdat JOU Op puv A[UO aWtTy 9UO Jv poauUte}gO saduvs UO paseq aie pazvoIpul satdads Jo siequinu 9sYyy, :FLON UOUULUO quepunqy P 7" i ‘W 0 OGI-6I V V ; ‘WW & OGI-OL ae ey juvpunqy juvpunqy eV. Ig quvpunqy aunt quepunqy G g 8% henson eae 1<0'0 ree L¥I 81d PaxOO1D aT uOWIWOD al Paes sees Oe 9'GI SSS cx [oer | aap yuepunqe uowwoy | jJuepunqy £00'°0 mene = : 5 A[ayeIOPOJ [ar | ST es TL9'8 61-8 v | epInog | juepunqe uowwloy | Juepunqy | -p., 27. : Speen: , SLIVAGIORLLEE ST 0} asiedg ars) Il 60'0-F10°0 OTT T3@e-GTl | 8-0 HA L0qiy stg uowuI0D | jJUuepunqy A spss 10'0 : ah Et : one alte puny) eee eee £0°0-G0'0 ees FOCI GOI-OL 66 Y IIV avzle (wdd) uaaIg use1s-on| g satoeds satveds eTq8{9S quvpunqy YO PITA 2 ce) a ee S oa) Aauaamg enboouryyy =| 3 =) co A ee G 5 quepunqy| juepunqy ee ee €00'0 5 ‘ BEBE UO0I}L}IBIA JOBIVT Ay SHAV'] AOVNIVUC] VALV AA CUVHT NISNOOSIAA, T TIdvL TABLE 2 OccURRENCE OF ALGAE IN Four WISCONSIN HARD WATER LAKES (From Sawyer, Lackey, and Lenz, 1943) Number of species, with percentage of their occurrence in samples | Lake and Kegonsa Wingra No. of Samples (9) (30) (25) (10) Dinoflagellates fo | aso | 2 c50%) | 3 (23%) Cryptophyceae 4 (50% 5 (49%) | 5 (56%) ) ) ) Chrysophyceae 6 (18% 8 (12%) 8 (15% 10 (23%) Euglenophyta 8 (10%) 8 ( 7%) 8 (15%) Chlorophyt eerie) 16 (23%) | 35( 9%) | 26(14%) | 41 (24%) remains low during the spring and summer months but increases during the fall and winter periods when there is a reduction in the plankton. In general, where the total phosphate and nitrate con- tent of drainage lakes is high, the algal flora is abundant. This relationship is clearly demonstrated by the higher productivity of plankton bulk in such lakes as Jordan in Michigan and Wingra in Wisconsin when compared with the productivity of lakes in the northern areas. It is noteworthy that in some of the Yahara River lakes near Madison there is a significant relationship between exces- sive growths and blooms of algae and the high phosphate-nitrate content resulting from sewage effluents and run-off water from populated areas. A similar condition is observable in Jordan Lake, Michigan, and in some of the eutrophic lakes in northwestern Iowa which have received a continuous flow of fertilizing elements during the past few decades. Lake Mendota, Dane County, Wisconsin, in the Yahara River sys- tem, is a typical hard water drainage lake. The pH ranges from 7.4 [17] TABLE 8 ABUNDANCE OF THREE CLAssEs OF ALGAE, LAKE MENDOTA, WISCONSIN Average number of individuals per liter of lake water (22 spp.) (6 spp. ) (15 spp.) January 612 1,668 February eae at 1,912 754 March 31 879 414 April 130 504 1,661 May 2,695 June 13,059 July 3,904 September 10,413 October 398 1,969 28,751 November 155 4,666 5,016 December 114 782 17,780 Norte: Readings for August were not available for the table. in February to 8.6 (surface level) in August and October. In Feb- ruary, readings for carbonates at 21 meters have been as high as 43 ppm. Fixed carbon dioxide is relatively high, 36-37 ppm. Hardness is 163 mg. per liter (American Public Health Unit). Inor- ganic nitrogen is 0.08-0.36 ppm, whereas total nitrogen varies from 13.1 ppm at the surface to 15.2 ppm at 22 meters depth (June). Sol- uble phosphorus occurs in 0.01-0.02 ppm. Correlated with these physical-chemical characteristics, the algal flora is predominantly the cyanophyte-diatom type, although during summer months there may be a dense growth of Staurastrum (a desmid genus), which gives the Chlorophyta a larger representation as far as number of in- dividuals is concerned. The over-all bulk of algal vegetation is not so great in Lake Mendota as in some of the other bodies of water in the [ 18 ] Yahara River system, but water blooms occasionally develop in it. The average number of individuals per liter of lake water for the Chlorophyta, the Cyanophyta, and the diatoms are listed in Table 3. These figures were obtained by counts from centrifuged plankton samples from Lake Mendota, Wisconsin, a typical hard water drain- age lake. It will be noted that it is only in the months of May, June, and July that the Chlorophyta exceed the Cyanophyta in numbers per liter. It is interesting also to note that the numbers represent 22 species of Chlorophyta, only 6 species of Cyanophyta, and 15 species of diatoms. This is a more nearly equal distribution of species among these three groups of algae than usually occurs in a hard water drainage lake when sedentary or attached species, as well as plank- tonic forms, are considered. HARD WATER SEEPAGE LAKES This type of lake is rarely found in our region, for seepage lakes are characteristically soft. Spider and Round Lakes, Vilas County, Wisconsin, are examples. Sloughs which have no outlet and some swampy ponds might be included in this class. Characteristics of hard water seepage lakes are shown in Table 4. These habitats, as might be expected, are not unlike the northern hard water drainage lakes except that the chlorophycean flora equals or exceeds the cyan- ophycean in abundance. Although the pH of the water in such lakes was found to be always above neutral, it is likely that great varia- tions would be discovered if readings were made throughout the year. A much higher pH would be expected in late summer months because of increased photosynthetic activity which removes the half- bound carbon dioxide from the bicarbonates. Euglenoid genera, such as Phacus, Euglena, and Trachelomonas, and some of the Chrysophyta, Tribonema spp. and Synura uvella, for example, are typical components of the algal flora in hard water seepage lakes. SorT WATER DRAINAGE LAKES Soft water lakes are nearly always of the seepage type; a soft water lake with drainage, or a seepage lake with hard water, is sel- dom found. It will be noted in Table 5 that soft water drainage lakes have limnological and biological characteristics very similar to the soft water seepage type. The algal flora, in both quality and quantity, is predominantly chlorophycean. The phytoplankton is sparse, some- times lacking except for an occasional diatom. It is noteworthy also that the available total-nitrogen readings for soft water drainage [19] UOUIWOD) uowUO0D quepunqy quepunqy U0I}e}9B9A JosZ1e'T] eA] EUG '/ s quepunqy 0S uoWWIOD GG uOUIWOD ial avge usdI5y satoadg UOUIWOD) IZ quepunqy 6 9 “IT bate 8 eee Zor LZ mea eral (wdd ) (wdd) 799 useis-an|g gouvjonpuoy saroadg He penal SAAV'] ANVAAIAG YALV A GUV]T NISNOOSIAA yp aIaV, gL SL ayer] epidg aye'T punoy ysnojg sourD jso0'T ysnojg ee}, Ioqiy our UOUIWO7) auoN . : [2}sory, LI go1vog UOWIUOD UOUWWOD : ; 8T a UOUIULOD Q01B9S ; een ystqon go1v0s quepunqy UOUWWOD : ’ £6 T Q01v0g quepunqy uOUIWIOD 8h IT uoUUKOD erat seat uoulu05 ne Meee QOIVOS 90180 Or G 90189 alepundy: MOT euuy ST 9 uo1eja3—a ovaye avg[e (uidd ) qoBIv'] usaI5 useiZ-on|g d aye] saroadg saroadg a1qnjos SAV] AOVNIVUC] YALV AA LAOG NISNOOSI(A G TIavyL TABLE 6 A CoMPARISON OF WISCONSIN DRAINAGE (D) AND SEEPAGE (S) LAKES Fixed CO2 (aver. mg./L) 155,11 — .026 1.26 and diatoms Arbor Vitae (D) | 7.0-8.4 22.0 102 024 1.86 predominate Crystal (S) 6.0-6.4 1.4 Ste 016 0.48 pot Plankton Blue-green Conductance (averane 70) algal flora ++ Blue-greens and diatoms predominate Allequash- (D) Few species, not abundant + Species domi- nant but not abundant Few blue- greens +++ Blue-greens + Few species, but fairly abundant Few species, on bottom ++ ++ Abundant in Fishtrap (D) 7.1-8.0 17.5 52-70 .026 Gonnnon species and numbers Clear (S) 6.1-6.8 3.6 016 0.66 Rare Few The relative degree of abundance of blue-green algae is indicated by the plus and minus signs. lakes are higher than those for hard water drainage or soft water seepage types. This suggests that if other essential nutrients were present, the soft water drainage lake might be more productive. High nitrogen content is correlated seasonally with a low plankton count, for when the plankton is high, especially during summer months, the nitrogen content of the lake water is low, increasing, however, as the biota decreases in fall and winter. In many seepage, acid lakes (Lynx and Mary Lakes, Wisconsin, for example), the desmid flora has an abundance approaching that of bog lakes, which are highly productive. SoFT WATER SEEPAGE LAKES In Table 6 three typical hard water drainage lakes are compared with three soft water seepage bodies. The latter type of lake usually has a sandy bottom, with few bays and shallows; the nutrients are low in concentration and the half-bound carbon dioxide content is much less than in the drainage lake. In soft water habitats the algal flora is almost entirely planktonic, and even this is relatively scant. Filamentous algae are practically non-existent. In many such lakes, only sterile Mougeotia and Zygnema can be found, entangled about the culms of rushes that form sparse beds. Zooplankton is scarce in the soft water lakes, which further explains their general low produc- tivity of fish. The total plankton residue (dry weight analysis) in Crystal Lake, Wisconsin, is only 0.48 mg. per liter (Birge and Juday ). When a soft water lake is found capable of supporting a sub- stantial fish population, it is obvious that at least periodically there must be crops of phytoplankters of sufficient magnitude to support the intermediate zooplankton elements of the food chain. The pro- portionate production of fish in a soft water lake has been made very graphic in a paper by Juday (1942). One of his diagrams is shown in Figure 8. This illustrates the quantitative relationships of the sev- eral components of the biota as expressed in kilograms per hectare of lake surface (wet weight, ash-free computation). See also Table 7 for analyses of 27 soft water seepage lakes. One of the many interesting problems involved in the differences in production of soft and hard water lakes is the role played by hetero- trophic bacteria. The unanswered question is: Do the nature and abundance of the biota determine the kind and quantity of the bac- terial flora, or does the bacterial flora function critically in releasing nutrients which, if sufficient, make possible an abundant and varied algal flora through the overturn of organic matter? This is doubtless a vicious circle, but Henrici and McCoy (1938) and Henrici (1939) have shown that soft water, oligotrophic lakes have fewer bacteria [ 28 ] 2 eee eee e eee e-- Bottom flora Sewewwesccos Phytoplankton -----Dissolved organic matter Figure 3. Relative weights of various components of the biota and dissolved organic matter in Weber Lake, Wisconsin, a soft water seepage type. Scale: 4.9 sq. mm. = | kilogram per hectare. (From Juday, 1943) than hard water, eutrophic habitats. In their studies Henrici and McCoy (l.c.) show that the bacterial flora of the bottom is larger in numbers of individuals than that of open water and that, as might be expected, the difference between the bottom and upper level flora is greater in eutrophic than in oligotrophic lakes. In oligotrophic Crystal Lake, Vilas County, Wisconsin, for ex- ample, the bacteria count per cc. of bottom mud sampled was 2,160; whereas in Alexander, a eutrophic lake in Minnesota, the count was 144,240 per cc. of bottom “kalkgyttja.” In the former lake the total bacterial flora of the bottom (average bacteria per cc. x depth of the mud) was 38,880 as compared with 2,599,320 in Alexander Lake. In the examination of the open water of the two lakes, an inter- esting bacterial count was secured. In Crystal Lake the average was 80 organisms per cc.; in Alexander, 675 per cc. When the ratio of the number of bottom bacteria to open water bacteria in the two lakes is compared, an even greater difference is noted. In Crystal Lake the total open water flora (average bacteria per ce. x depth of the lake) is 159,900, which, when compared with 38,880 on the bottom, gives a quotient of 0.2. A much higher ratio is found in the eutrophic type of lake. In Alexander there was a total of 538,300 organisms in the [ 24 ] open water, or a quotient of 5.0 when this is compared with 2,599,320 in the total bottom count. The activity of bacteria produces food substances for bottom or- ganisms, as previously mentioned, and at the same time increases the concentration of nutrients available for plant and animal life in the upper levels. It is obvious that the quantity and quality of the bac- teria in both bottom and open water floras can produce effects in the chemical nature of the water, and in the chemistry and physical condition of the bottom sediments. In a sense a closed cycle is in- volved here. In the first place a rich bacterial flora, through the rapid breakdown of organic matter, may produce (at least indirectly) a varied and rich phytoplankton and zooplankton. The quantity and quality of the microbiota, in turn, have far reaching effects on the productivity of other kinds of animal life, both on the bottom and in open water. And finally, the relative abundance and quality of the organisms (i. e., productivity ) within a lake determine whether the bottom sediments will support a rich bacterial flora. The role of bacteria in this cycle has been clearly summarized by Waksman (1941). The characteristic paucity of nutrients in a seepage lake is explain- able, at least in some instances, by the source of the water, which percolates through sand and crystalline soils. Frequently there is seepage from bogs and marshes, with the result that the water is rich in humic acids. Birge and Juday found only 3-4 grams of or- ganic matter per cubic meter in the soft water type of lake; of this amount, 15-18 per cent was accounted for by the plankton. Over a three-year period they found that the total nitrogen content of such a lake averaged 7.2 per cent of the dry weight of the plankton per cubic meter of water (as determined by ash-free analyses ). Table 7 lists 27 typical soft water seepage lakes with their biota and critical limnological features. Acip Boc LAKES The acid bog lake, usually found in Sphagnum bogs, is of the kettlehole type. The water is at times acid, although the marginal mat may be more acid than the open water. Here are found a great vari- ety of desmids and a few Cyanophyta, such as Scytonema ocellatum, Hapalosiphon pumilus, and Chroococcus Prescottii. The plankton of these lakes is not abundant, usually, but the filamentous forms are luxuriantly developed, especially in the marginal waters and in the small seeps leading into the lake. Such bodies of water are aging rapidly, and there is a great accumulation of organic matter, [ 25 ] aoIvag uoUTUOT) UOUIWOD rr Auowuepy 9T v aorRos ‘yyurd may uowlUutoD uoureIq 0} MO UOWIWIOD 9G OI ; P ; 9dIvOS UOULUWIOT) uWOUIWWOT) (‘OD Yeung) 0} MO cP ial splaaqd uowuwoy | WOH cI MOV OCG (O- SeItA) uoyyurTg Z | uoyUrT 0 yewsdIn o9uou UOUTULOT) 90IBOS Aqpwonoerg CT g Mog UOUIUIOT) 9dIBIS . ae (‘OD epreuc) CG L AF) (9) MOA UOUWIWUOD 9OIBIS 4 ae roquedieyy 96 G Mag UOUIWIOD Q0IVIS LT ‘puog Caen Sng LG q uOWILOD WOUND) noises Ze oreyng LT G UOUWIUIOD UOWUWOTZ) UOWLWIOD . c9'0 ‘wort 7s wen 31 UOLULUOD UOUILUOD) Sr g UOT]e}ABAA avgye ovale (urd) (wudd) (uidd) 3 uddID ugei3-an|g Si panes satoadg satvadg ayqnyos N 2 SANW] JOVdAAS HALVAA LAOS NISNOOSIAA L qIavy WoulutOT) 9IIBIS c 8 G UOWWUOD BOIBOS L 6 9g V 4 uotulwor) all juepunqy UOUIWIOD 9dIBIS 8 g UOUIUOD) uoWwWOD G € UOUIWOZ) dOIVIS 8T 8 uoww05 UOWUUIOT) UOUIUIOZ) 9S S juepunqy UOLUUOD) QOIIS 8h $ 8 i }-|- uOUILUOD uOWULOD GP $ uOUIUOD IDIBIS 8I 8 3) 90189 BIRDS BIDS Ms uoWUOD UOUILUOD UOUIUOT) 86 ZI UOLUUIOZ WOULD) UOWIWOT) 6 L uoumuo0D UOWILUOZ) UOWIUIOD AL OT Maa uoWWOZD uoWILUOD Gs ih J39q9M youqiozey o39MSO cary: aera (OD settA) HE is! Suc] youljayH eo Yo) ce — re <2) i S | So a} a Silane Oo} 1. 4 ee) mt - st Na) 0'9-G'S st I a Ne) WG {ALD) 8's 8s = = w S 4 ee tal much of which eventually forms peat because it is only partially de- cayed by bacterial action. Microspora spp. are often the dominant filamentous forms, attached to Chamaedaphne stems at the margin of the open water. It has been observed that Oedogonium, often abundant in the vegetative condition, in the open water portion of acid bog lakes, rarely reproduces sexually there. In the pools and ditches of the marginal mat, however, where there is a concentration of organic acids and decaying matter, and where temperatures are higher, fruiting plants are abundant and numerous species may be identified in a single collection. Batrachospermum spp., in luxuriant tufts, are also characteristic of the acid bog lake. In general it may be stated that this type of lake, when shallow enough to permit opti- mal temperatures, is more productive than any of the other types in number of algal species. ALKALINE Boc LAKES The alkaline or basic bog lake usually involves a stream meander- ing through a kettlehole depression which has never been entirely closed. Mud Lake, Cheboygan County, Michigan, and a small lake near High Lake, Vilas County, Wisconsin, are clear examples. Al- though there is an acid type of terrestrial flora forming a marginal mat around such lakes, the water is fairly hard. The pH is 7.1-7.4, the bound carbon dioxide is 21.8 ppm and calcium is 11.25 ppm; the conductivity 85. They have, therefore, the chemistry of semi- hard lakes, but the algal flora is poor both quantitatively and qual- itatively. There is a conspicuous growth of Spirogyra crassa, S. decemina, and Chara spp., all calcophiles (hard water organisms ). SUMMARY Some of the correlations between types of algal floras and physi- cal-chemical conditions in lakes are summarized in the charts in Figures 4, 5, and 6. The diagrams are based on analyses of 100 lakes in Vilas and Oneida counties, Wisconsin, selected at random from the list of habitats from which collections were made. The samples upon which counts of algal species are based were collected during July and August. The chemical data are from the records of E. A. Birge and C. Juday. In Figure 4 the graph at the left shows the distribution of the lakes according to pH readings (expressed in number of lakes which fall within the pH range indicated). As will be noted, the majority of the lakes in the sample have a pH near 7.5. Only a few are as basic as 8.3; a somewhat larger number are as acid as 5.3. Correlated [ 28 ] BLUE- GREEN GREEN ALGAE ALGAE a Figure 4. Diagram showing the number of Wisconsin lakes (in a random sample of 100) which lie within different pH readings; their bound carbon dioxide content (expressed in parts per million); and the percentages of green and blue-green algal species in their total algal flora. (See discussion in text. ) [ 29 ] with this distribution is the first graph to the right, which shows the amount of bound carbon dioxide that occurs in the lakes (expressed in parts per million). As would be expected, since the majority have a pH above neutral, most of the lakes have a relatively high bound carbon dioxide content in the form of calcium and magnesium car- bonates. In the particular group of lakes under consideration the bound carbon dioxide content was no higher than 14 ppm, however. The graphs on the right of this diagram show the distribution of green and blue-green algal species (expressed in percentages of the lakes’ total algal flora). It will be noted that where both the bound carbon dioxide and the pH are high the percentages of blue-green and green species are approximately equal. With a lowering of the pH and a corresponding decrease in the amount of bound carbon dioxide, however, there is an increase in the percentage of green algal species, reaching 100 per cent of the flora in the highly acid lakes. This increase is in almost exact inverse proportion to the decrease in the carbon dioxide content. In this connection it should be pointed out that there is no causal relationship between large numbers of individuals or numbers of species and high bound car- bon dioxide content since in this form it is unavailable to most vege- tation. Bound carbon dioxide content is significant, however, and is useful in providing an index of algal production, because almost in- variably a lake with a high bound carbon dioxide content will also be high in bicarbonates. Half-bound carbon dioxide in Ca(CO3)o and MgCa(CO3)z is available to photosynthetic organisms, and it follows that such lakes are able to support an abundant algal flora, other factors being also favorable. Whereas the relationship between half-bound and bound carbon dioxide mentioned above usually holds, it is possible in senescent lakes to have a high bound carbon dioxide content with little or no half-bound or free carbon dioxide. In such cases one would expect to find a very scanty algal flora and a heavy deposition of marl or some similar carbonate. See Welch (1935) for an outline of the relationship between available carbon dioxide and bicarbonates. In Figures 5 and 6, the lakes used in this analysis are divided into four groups: hard water drainage (HD), soft water drainage (SD), hard water seepage (HS), and soft water seepage (SS). In Figure 5 the distribution of the hard and soft water drainage lakes according to pH readings is shown in the graph on the left. With this distribu- tion is compared bound carbon dioxide content, as in Figure 4. As was noted in Figure 4, the blue-green and green algae are present in almost equal percentages in the hard water lakes; the acid lakes have by far the larger percentage of green algae and almost no blue-green [ 30 ] > @® ae ©) om >mM m2 mcr ow a MPS>Oor > ZMMVO HARD : 9 NO SOFT 6 DRAINAGE % ALGAE SPECIES leet 0 5 0.0% Figure 5. Diagram showing the percentages of hard and soft water drainage lakes in a random sample of 100 Wisconsin lakes; their bound carbon dioxide content (expressed in parts per million); and the percentages of green and blue-green algal species in their total algal flora. (See discussion in text.) [31 ] BOUND CO, %, OF PPM ALGAE | SPECIES NO 753 001 TLARD [a hl TALAKES Mil , m= i TA: : ' | ‘ ' : bar in ‘ uJ ) ' t De ‘ ees 1 ‘ ut 1 ' ' ‘ ' ua GREEN ALGAE Figure 6. Diagram showing the relative number of hard and soft water seepage lakes in a random sample of 100 Wisconsin lakes; their bound carbon dioxide content (expressed in parts per million, the highest being 14); and the percentages of green and blue-green algal species in their total algal flora. (See discussion in text. ) [ 32 ] flora. The decidedly larger number of algal species in the highly basic lakes is related to the richness of the phytoplankton in such habitats. It is in lakes with pH readings such as these that blue-green species often produce water blooms. As was mentioned previously in another connection, hard water seepage lakes are rather rare. This is seen in Figure 6, which shows a few lakes having a pH between 7.2 and 7.7. In at least one of these lakes the bound carbon dioxide was as high as 14 ppm. In such lakes the green algal species are sometimes three times as numerous as the blue-green. A considerable number of soft water seepage lakes were found among those used in this analysis; most of these had a pH between 6.0 and 6.8. As with the soft water drainage lakes, the seepage lakes have floras predominantly of the green algal type. It should be men- tioned, however, that some of the soft water seepage lakes have a great bulk of certain blue-green algae, but the number of species is very small. [ 33 ] Relationships of Phytoplankton to Lake Productivity One of the more interesting problems confronting the aquatic bi- ologist, and one of great practical importance, is that of productivity. By this term is meant the quantity and quality of plant and animal life which a body of water is capable of supporting. Limnology com- prises such a heterogeneity of fields of inquiry that limnological studies often seem to lack correlation. Nevertheless, the chief aim of the limnologist is to devise methods of evaluating productivity of aquatic habitats for both purely scientific and practical purposes. Many of the problems that arise in shellfish culture, fish management programs, and similar projects are problems of productivity. Consid- erable progress in both the Old and New Worlds has been made in determining index characters by which productivity of aquat- ic environments can be evaluated and predicted; that is, a set of characteristics or standards by which a lake may be measured in respect to the quantity and kinds of plants and animals it can pro- duce. Physical-chemical factors, however, seem to defy analysis be- cause they interlock and interact in bewildering complexities. Since they are never quite the same in any two lakes, they give each body of water a distinct individuality. Thus limnologists find great diffi- culty in determining a productivity index which can be generally applied. A brief consideration of a few biological and physical-chem- ical factors involved in the relationships of the algae to productivity in lakes is in order here. No more graphic outline of the factors involved in production is at hand than a diagram prepared by D. S. Rawson (1940). Re- ferring to this diagram (reproduced here, Fig. 7), it is of interest to check through the factors, noting which ones have a direct bearing upon the quantity and quality of the algae and other plant life, factors which also influence animal life, of course, either directly or indirectly. As complex as this chart may appear, it is, of necessity, a simplified presentation of the multitudinous factors involved and shows none of the ramifying and anastomosing interactivities of the components. If the contributing agents shown in this chart were to be analyzed further, the diagram would become very much in- [ 34 ] Geographic Location lume! eolog) Latitude es S jical Topogra’ Lonat Influence Formation pography \\\ a A sare Compas Shape of Basin Climate ; as iti i Bottom Precipitation Wind Insolation ret Ha ccs ae Se jaterial oe int of Seasonal Cycle pains of Inflow a Trans- Light Heat Reostrattce aS Oees Penetr. Devel eats osente cre pareacy — oF ue Stratthcation Utincation Growing Season — 1D Trophic Nature of the Lake Amount, com and distribution of Prengal petal Also rates of circulation. “Productivity” Figure 7. A diagram showing the contributions toward lake productivity by some interesting factors, both inside and outside of a body of water After a diagram by D. S. Rawson. (By courtesy of the American Association for the Advancement of Science. ) volved. For example, ‘primary nutritive materials’ depend on many specific factors which are interrelated with and are governed by ‘topography, ‘drainage area,’ and the ‘inflow of allocthonous mater- ials.’ The availability to plants of the ‘primary nutrient materials, such as nitrogen, phosphorus, and various salts, would be, in part, determined by ‘oxygen concentration and utilization, as well as by the ‘seasonal cycle of circulation and stagnation.’ ‘Depth’ and ‘wind’ together, or wind alone, directly affect turbidity (‘transparency’), [ 35 ] which in turn determines ‘light penetration. The amount of carbon dioxide (not indicated as such on the chart) is regulated by a num- ber of factors shown in this chart. Carbon dioxide plays an important role, of course, because of its relationship to photosynthesis and hence to the amount of plant life. As has been pointed out by Chandler (1944) all these factors fall into three groups or classes: edaphic, morphometric, and climatic. In this paper he relates seasonal pulses and annual variations in the quantity and quality of the phytoplankton to some of these factors. He found the most important to be turbidity, solar radiation, and temperature. CHLOROPHYLL AS AN INDEX OF PRODUCTION It is sufficient to say that chlorophyll in water plants, as in land plants, is the all-important agent and initiator in a series of physical- chemical changes which culminate in and are responsible for the fauna. In this connection, mention should be made here of the pos- sible use of chlorophyll measurements as indirect, if not direct, in- dices of potential productivity. An approach to such an evaluation of production has been de- scribed by Kozminski (1938). He secured acetone extractions of chlorophyll from the phytoplankton at different lake levels and then made quantitative readings by measuring the absorption of light waves 6200-6800 A in length. By this photometric method he was able to secure an index of phytoplankton production in terms of the amount of chlorophyll at different lake levels. By plotting the chlor- ophyll (expressed in Mg./M*) against depth in meters a useful in- dex of the amount of phytoplankton at different levels is obtained. Then when the curves from various lakes are compared an evalua- tion of respective productivity potentials is established on the basis of the available chlorophyll. (See Fig. 8. ) It is interesting to correlate these readings (Fig. 8) with the qual- ity of the phytoplankton and limnological characteristics. In Scaf- fold Lake, Wisconsin, for example, there is shown to be very great absorption of light in photometric tests, especially between 2 and 8 meters, and we find a very dense flora of nannoplankters. At the time observations were made, the lake had a peculiar bluish-tan color from a tremendous population of the chlorobacteriacean Pelogloea bacil- lifera. This is a colonial organism with minute cells rather loosely held in soft mucilage. In a plankton net, the aggregates usually break up and only individual cells or small clumps appear when the [ 36 ] CrioropHyyy in Mo/M® Figure 8. Graph showing vertical distribution of chlorophyll as determined by Kozminski’s photometric studies of a number of Wisconsin lakes. C— Crystal; H—Helmet; Ma—Mary; Mu—Muskellunge; Sc—Scaffold. The ordinate represents depth in meters. The high chlorophyll-content of Scaffold Lake at eight meters is caused by an abundant growth of Pelogloea bacillifera Lauterbon. (From Kozminski, 1938. ) sample is examined microscopically. The organism is easily mistaken for a cluster of bacterial cells. In Scaffold Lake, Pelogloea bacillifera was apparently the only organism responsible for the heavy absorp- tion in Kozminski’s photometric analyses. Phormidium mucicola was the only other species found, and this was seen only after samples of the lake water had been cultured in the laboratory. The rather curious flora of Scaffold Lake is accompanied by an equally interesting chemistry. The pH is high in the upper levels (pH 8.6-9.2) but drops to 6.3 at‘nine meters. Bound carbon dioxide is relatively low at the surface (5.0 ppm), but rises to 14.9 ppm at the bottom. Free carbon dioxide is likewise low at the surface (3.0 ppm) but is plentiful at or near the bottom (41.0 ppm). Calcium is present in 2.37-2.83 ppm. The color index is 26 (platinum cobalt scale). These data make it possible to classify Scaffold Lake as a medium hard water habitat, capable of supporting a luxuriant algal flora; hence it could be said to have a high production potentiality. An index to this is also to be found in Kozminski’s chlorophyll analy- ses. (See also the remarks by Dutton, 1941, p. 397; Dutton and Man- ning, 1941, p. 516; Manning and Juday, 1941, p. 363. ) In such a transparent lake as Crystal (Wisconsin) the chlorophyll content is relatively low at all levels (Fig. 8), but shows a slight in- crease near the bottom. This is in keeping with the prediction one [ 37 ] would be able to make on productivity of this lake from a considera- tion of other limnological features. The pH is low (6.0-6.4). The free carbon dioxide is 1.25 ppm near the surface, although at the bottom it is high, 10.5 ppm. The conductivity is low, the mineral content al- most non-existent. It is reported that the water from Crystal Lake can be used safely in storage batteries. Repeated tow samples from this lake (July-August) yielded scarcely a single plankter, and there was a negligible amount of attached filamentous algae in the shallow water zone. On the bottom, at 10-15 meters, however, there is a car- pet of the aquatic moss Drepanocladus fluitans and a meager algal flora of 15 species (including desmids). The stratum of vegetation accounts for the rise in chlorophyll content, shown by Kozminski (I.c.), in a layer where there is also an increase in the amount of available carbon dioxide. PHYSICAL-CHEMICAL FACTORS The quantity and quality of the algal flora is affected by many edaphic factors, and in turn these plants produce effects in the phys- ical-chemical factors in the medium. These effects may directly or in- directly influence the biota of the environment, sometimes very dras- tically. Algae alter the oxygen and carbon dioxide content of the water, cause the pH to fluctuate, contribute to the nature of bottom sediments, and in other ways initiate series of cause-effect inter- actions. It is recognized that these changes are involved in what may be called algal ecology. This is an ill-defined term and broad in its application because it must cover such a complex of interacting fac- tors and processes of nature. Since life itself is the product of these processes and the responses that protoplasm makes to them, it is not possible to regard any one ecological factor as more important than another. Carbon dioxide and oxygen might be selected arbitrarily for primary consideration. CARBON DIOXIDE Carbon dioxide and carbon dioxide tension (Burr, 1941) are criti- cally important and only those bodies of water abundantly supplied with this gas, free or at least available, can support a luxuriant growth of algae. The quantity of carbon dioxide is regulated by a number of factors, many of which, in turn, are related to climatic conditions and geological events of the remote past. The temperature of the water at different times of the year and in different strata, the amount of carbon dioxide released by respiration, the chemical nature of the bottom and the overturn of organic matter by bacteria, [ 38 ] the geographical and physiographic features of the terrain surround- ing the water (or, in the case of a river, the land drained by it), all have their bearing on the carbon dioxide content. Because of its crucial position in the lake’s metabolism, a radical unbalancing of the amount of carbon dioxide in solution is felt throughout the entire biological cycle. A minimum amount will limit the quantity of phytoplankton a body of water can support, as indicated above in the remarks on Crystal Lake. A boundless supply, together with other favorable conditions, may influence the development of a superabundant water bloom, followed by a series of disturbed biological conditions. Examples of this are to be found in the prevalent water blooms in southern Michigan and Wisconsin, in Minnesota, and in some northern Iowa lakes. Only rarely have northern lakes been found with floras which approach the bloom condition. In southern parts of Wisconsin, the richness of the algal flora in the limestone region, as previously mentioned, is related to a high bound and half-bound carbon dioxide content. For example, Lake Geneva in Walworth County contains an average of 20.7 ppm of calcium and 3.7 ppm of carbonates. Trout Lake in Vilas County, a medium hard water lake, contains but 6.7 ppm of calcium and no carbonates. This great difference in the amount of available carbon dioxide is correlated with a great dissimilarity of the floras. Lake Geneva has at times a dense bloom of the eutrophic type, but in Trout Lake there is a relatively scant growth of algae in the main body of water. Birge and Juday (1911) have shown that there may be as many as 1000 phytoplankters per liter (mostly Oscil- latoria sp.) at a depth of 15 meters in Lake Geneva At this level, free oxygen was 2.4 ppm and the temperature was 13.6° C. It may be of interest here to point out that the number of phytoplankters may be as high as 9 million (filaments, not cells) per liter in hard water lakes during periods when water blooms flourish (Prescott, 1932). Although an adequate supply of carbon dioxide is essential, an in- crease in carbon dioxide tension, especially if rapid, may either kill fish or seriously upset their physiology. Death is brought about more or less directly through failure in elimination of carbon dioxide from the body on account of the high concentration of carbon dioxide in the water, or indirectly through ionization forming injurious car- bonic acid (Powers, Shields, and Hickman, 1939). Again, the basic chemistry of a lake varies greatly as carbon diox- ide is removed from the bicarbonates. Some Iowa lakes that I sur- veyed developed a pH of 9.6-9.8 in the upper zones during the sum- mer period of accelerated photosynthesis; an increase for the period [ 39 ] of as much as 2.4. This is, of course, a logarithmic expression of in- crease and represents an enormous change in water chemistry with far-reaching biological effects. OxYGEN It is obvious that oxygen is one of the primary limiting and deter- mining factors in phytoplankton ecology, as for all other forms of life. Because of their photosynthetic activities, plants in daylight are practically independent of free oxygen in solution. When carbon di- oxide is present in sufficient quantities and other factors are favor- able, chlorophyll-bearing organisms can automatically maintain the required amount of oxygen needed for their own respiration. But at night plants are required to draw upon free oxygen in the surround- ing medium for this process. When there are excessive growths of algae, particularly in warm shallow water when the oxygen content is low, the available supply of oxygen may be reduced to a point be- low the amount normally required by the fauna. Thus, by increasing or decreasing the oxygen content, algae act as agents in determining the quantity and kinds of animal life which a body of water may support at different levels. Photosynthesis, however, is regulated by such factors as carbon dioxide, discussed above, and light. LIGHT Illumination as an ecological factor determines that most algae, particularly plankters, occupy what is termed the photosynthetic zone, the upper 2-5 meters of water. Turbidity, color, and amount of disturbance at the surface all help to determine the depth to which light favorable for photosynthesis will penetrate. Because of the great amount of light lost at the surface through reflection and be- cause of further reductions by absorption and diffusion, photosyn- thetic plants are required to carry on their activities in the upper levels. This explains the (usually) greater quantity of dissolved oxy- gen in this stratum. The exhaustive studies of Birge and Juday (1911) describe the gas content and its fluctuations in 156 lakes. Their graphs clearly illustrate this relationship between oxygen and the photosynthetic zone. In their Figure 135 (p. 243), curves are shown for the oxygen content of Lake Mendota, Wisconsin, in July. At this time there was a heavy growth of phytoplankters (Coelos- phaerium sp., Aphanizomenon flos-aquae ) of more than 5000 organ- isms per liter. At the surface, the oxygen content was 6.6 ppm. From the surface flora the number of algae was irregularly reduced to about 1000 per liter at 20 meters, where the oxygen content was only 0.1 ppm. In May of the same year in which the above readings [ 40 ] were made, the surface waters of Lake Mendota showed 28.5 ppm of calcium and 5.0 ppm of carbonates. This lake lies in the limestone region of the state and supports a eutrophic type of flora. NITROGEN AND PHOSPHORUS Special mention should be made of the significant roles of nitro- gen in its various forms, and of phosphorus. The importance of these nutrients has been measured, although somewhat incompletely. That they are potential determiners of ultimate productivity is evidenced clearly by the many limnological studies which have related high nitrogen and phosphorus readings to luxuriant phytoplankton floras (Harvey, 1926; Wiebe, et al, 1929; Domogalla and Fred, 1926). The negative correlation of relatively high concentrations of these elements with periods of phytoplankton minima provides inferen- tial evidence of their use by green plants. That is, when nitrates and phosphorus are low the phytoplankton population is high, the nutrients being consumed and stored in the organisms. When the phytoplankton decreases through an accelerated death rate and distintegration occurs, the elements are released and their per- centages in the chemistry of the lake rises. Nitrogen enters di- rectly into the phytoplankton cycle. Nitrogen content, in turn, is dependent upon several physical processes in and around the body of water (run-off from agricultural lands, for example). The nature of the bacterial flora, therefore, the chemistry of the drain- age water, and the presence or absence of nitrogen-fixing bacteria and algae, are some of the more important factors determining nitrogen content. High oxygen content permits a rich plankton flora, but when nitrogen is low or absent, many kinds of algae are excluded from the flora. Some species of the Cyanophyta are especially rich in proteins and require, therefore, a highly nitro- genous medium. Thus a dense bloom of Aphanizomenon flos- aquae or Microcystis aeruginosa would account for a great fluctua- tion in the free nitrogen and nitrate content of lake water at different periods of the year. Nitrogen fixation by some species of blue-green algae (see De, 1939; Fogg, 1942; Fritsch and De, 1938; Hutchinson, 1944) is also involved here. This specific relationship to nitrogen fixation is a reminder of the many reasons that limnological studies which involve analyses of the biota should include specific, not merely generic, determinations of the organisms concerned. Lim- nologists not infrequently list only algal genera in the published results of their studies, and this is not in keeping with the best scientific procedure. Here it might be well to recall that although nitrogen content, carbon dioxide, phosphorus, and other elements are able to deter- [ 41 ] mine abundance of the algal flora, they also influence the variety, i.e., the kinds, of species present. As mentioned before, it does not follow that because water is a universal and standard medium selectivity is not being exercised rigorously. So clear-cut are some qualitative selections operating in algal ecology that the phycologist is able to use the presence of certain species or groups of species as indi- cators of physical-chemical conditions in a body of water. Without hydrogen ion determination equipment but just by observing the quantity and quality of the algal flora, especially the phytoplankters, the experienced worker can estimate the acidity or alkalinity (some- what roughly to be sure) and the relative abundance of carbon dioxide; can predict whether there is a rich or poor supply of nitrates; and can tell something of other limnological features in a habitat. BotrroM DEPosITS Another way in which modification of phytoplankton quantity and quality may come about is through the effects produced in bottom sediments when organic matter decomposes. The composi- tion of the silt, or ‘Gyttja’, determines the quality of the bacterial flora, a group of organisms which is important in fixing the manner and speed with which nutrient elements are returned to solution. It is obvious, of course, that the kind and quantity of biota supported in the water above, as well as on, the floor influence the physical and chemical nature of the bottom sediments, which, in turn, acts in de- termining the number and, to a certain extent the kinds of bacteria in the sediments. Also, a lake bottom which supports dense popula- tions of mollusks and midge larvae will be affected by the fauna. In a lake where a luxuriant phytoplankton has become established, especially in a cyanophycean lake, a great accumulation of nitro- genous matter may result, As mentioned above, some of the blue- green algae are nitrogen fixers, and many of them are great accumu- lators of this element, Thus their physiology may result in an ever-increasing supply of organic nitrogen in a lake. With bacterial turnover, nitrogen appears first in one form and then another, and eventually alters the chemistry of the water above bottom sediments and so influences the biota. Thus a closed cycle of interchanging and interacting phenomena is seen to be operating within a lake. The processes which make up the cycle are forever fluctuating. It is easy, therefore, to use the analogy so often made between organic metabolism and the flux, reflux, and pulsations within a body of water. The productivity of an aquatic habitat is achieved by its ‘metabolism.’ [ 42 ] QUALITY OF ALGAL FLORAS The physical-chemical factors of the environment act not only in selecting the quality of a flora, but sometimes the very quality deter- mines the quantity. A single example to illustrate this is the fre- quently encountered case of two lakes which support quite different qualities of phytoplankton, one predominantly chlorophycean, the other conspicuously cyanophycean. The factors which have acted selectively to determine the qualities of these floras are well known and include those mentioned above. The cyanophycean lake is high in nitrogen, there is a relatively large amount of phosphorus avail- able, the water is alkaline, with a pH ranging from 7.2 to 9.5, and there is an abundance of free carbon dioxide or half-bound carbon ~ dioxide. This is the eutrophic type of lake and because frequently it is relatively shallow the summer temperatures are high (25-30 C»): Thus, although the characteristics of the hard water lake are far from being detrimental to a chlorophycean flora, the combination of factors is such that an ultra-favorable habitat is provided for the blue-green algae and the diatoms. It is well known that the phys- iology of many species in these groups is such that they are able to carry on cell division and vegetative reproduction at an astoundingly high rate. In fact, certain species of blue-green algae are so much more successful in this respect than others even in the same group, that they completely take over at the expense of competing forms. Some pelagic Anabaena spp., Aphanizomenon flos-aquae, Gloeo- trichia echinulata, Coelosphaerium Naegelianum, or Microcystis aeruginosa, for example, either singly or together, may constitute nearly 100 per cent of both the quantity and the variety of the phyto- plankton because of their ability to reproduce rapidly. These organ- isms are often responsible for water blooms, the excessive growth being directly related to the quality of the flora. In the chlorophycean lake, which frequently is the oligotrophic type, there is a minimum of nitrogen and phosphorus, the water is deeper than in the cyanophycean lake, there is proportionately less water in contact with the bottom, and the temperature is generally lower. Although the surface temperature may be the same in the two lakes at a given time in mid or late summer, the chlorophycean lake reaches its maximum temperature at a later date than the eutrophic or cyanophycean lake because of the greater amount of water in the hypolimnion and because of the greater time consumed in the spring-summer overturn. With little carbon dioxide available, there is no opportunity for a luxuriant growth of phytoplankters. The flora that does develop here may contain many blue-green and diatom species, but the greatest number of forms are chlorophycean. Even [ 48 ] under ideal conditions, green algae and most diatoms seldom, if ever, form a bulky phytoplankton which can compare with the enormous and overwhelming blue-green algal blooms frequently encountered in hard water lakes, for their rate of reproduction is lower. Further- more, green algae do not form sticky, floating mats of vegetation as do many of the cyanophycean species. Hence, the quantity of the algal vegetation is related to the kinds of plants that become estab- lished in a lake. It is well known that some oligotrophic lakes are practically bar- ren of a microflora, as well as being almost entirely devoid of higher aquatic plants. See Table 1, which shows a comparison of the nitro- gen content and the quality of the plankton. WATER BLOOMS Serious economic problems and drastically unbalanced biological conditions frequently arise in sluggish streams and in lakes which are physico-chemically constituted to support a luxuriant water bloom. This is particularly true in southern Michigan and Wisconsin, as previously mentioned, where a body of water may become over- grown with cyanophycean species, many of which have the habit of floating high in the water. Their tremendous numbers cause floating crusts and scums to form, wherein plants die quickly and disinte- grate in the intense sunlight. The living plants and the increased bacterial flora resulting from their decay after death deplete the oxy- gen below the point required for fish (2-3 ppm) and other animals. In my study of Iowa lakes I observed similar abundant blue-green floras. After a few hot days and nights in summer, when the oxygen was low in any case, a climax situation developed. The dissolved oxygen dropped to zero around midnight, with the result that within a few hours not a single living animal could be found in a lake with such a water bloom. Even bottom organisms, adapted to low oxygen supply, were killed, and there was a mass of dead Chironomus lar- vae and microcrustacea near the shore and in the shallows of bays. After such a climax, dead fish appeared within a few days, first float- ing at the surface and then collecting in heaps along the beaches. Thus enormous loss in game fish was sustained as a result of super- abundant growth of blue-green algae. I have some evidence that fish may be killed also by poisonous substances, such as hydroxylamine, produced from the decay of pro- teins with which blue-green algae are abundantly supplied. Fitch et al. (1934) have described the poisoning of domestic animals by toxic substances produced by certain species of these plants. [ 44 ] Excessive growths of phytoplankters may be costly in another way; they may interfere both chemically and physically with the operation of city water systems in which lakes, reservoirs, and filters are involved. Copper sulphate (Moore and Kellerman, 1905; Domo- galla, 1941; Prescott, 1938), chlorine, sodium arsenite (Surber, 1929; Wiebe, 1930) and activated carbon are required to control algae or to eradicate objectionable tastes and odors produced by them. Sand filters are easily clogged by some species of algae such as Melosira spp. and Aphanizomenon flos-aquae, and must be cleaned frequently. Recreational sites are ruined and open bathing pools are rendered unusable when phytoplankters take advantage of optimal lim- nological conditions. THE FOOD CHAIN No single phase of the great cycle of events which occur with- in a water habitat is of greater importance to the main problem of productivity than the one which involves physiological activities carried on by the algal portion of the biota, especially the phyto- plankton. This is particularly true because the phytoplankton is related to the food chain of aquatic animals, especially in lakes where larger aquatic vegetation is scarce. Chandler (1944) has pointed this out in connection with his studies of Lake Erie. No other group of organisms in a body of water, unless it be the bacteria, can produce such far-reaching effects by fluctuation in quality and quantity. This leads to a consideration of the familiar position which phyto- plankton and other forms of vegetation occupy in the food chain of animals. That algae deserve the often applied term, ‘pasturage of the sea,’ is seldom denied, and it is fairly well agreed that they hold a basic position in the food cycle of both fresh and salt water animals. At the same time, many published studies, beginning with the work of Pitter published in 1909 (see also Petersen and Petersen, 1911), have raised a question concerning the degree to which aquatic animals are directly dependent upon phytoplankters. Hardly any of these papers which have pointed out aquatic animals’ inde- pendence of phytoplankton made claims that all the microfauna subsists on nutrients of a non-particulate nature. Some students have shown, rather convincingly, that at least certain zooplankters are not directly supported by plants but are able, on the other hand, to take nourishment from colloidal matter, organic debris, and, to a minor degree, from substances in solution. In some such studies nannoplankters have been shown to be the source of food when [ 45 ] larger phytoplankters have been excluded from the diet of experi- mental animals such as Calanus (Clarke and Gellis, 1935). Furthermore, other researchers have indicated that the concentra- tion of dissolved and colloidal matter used in the culturing of lab- oratory animals was greater than the normal concentration of these substances in nature which is supposedly not sufficient to maintain microfaunal populations. Thus the burden of direct support is thrown back on the phytoplankton. It is noteworthy that although the idea that phytoplankters are im- portant in the food chain is apparently sound and generally accep- ted, it is borne out by relatively few published scientific observations. It is evident that there is much to be learned in this connection, and the question certainly merits considerable attention both in the field and in the laboratory. This is especially true, since so many predic- tions and evaluations of productivity are based, in part, on the as- sumption that phytoplanktonic components in the biota are of basic importance in the food chain. A clear understanding of the exact nature of this problem must be reached before the quality and quan- tity of phytoplankton can be used as dependable indices of pro- ductivity. There are many published studies bearing out the correlation between seasonal maxima in phytoplankton and peaks in microfau- nal populations. The inference usually drawn from this correlation is that the increased phytoplankton makes possible a larger microfau- nal foraging population, which in turn would support a more numerous macrofauna. But it is not known whether the microfauna achieves maxima after a peak in the phytoplanktonic population because it feeds directly on the plants, or because it is nourished by particulate matter resulting from the plants’ disintegration. Whatever the precise relationships are between the algae and the eventual productivity of fish and other animal life, it is well known that lakes with a luxuriant flora maintain a correspondingly dense population of animals. This relationship is illustrated many times over in lakes of the Michigan and Wisconsin area. Post Lake, Lang- lade County, Wisconsin, for example, and Ocqueoc Lake, Michigan, are highly productive and excellent for game fish, as many as eight species occurring in the former. These are medium hard water lakes and characteristically support a luxuriant vegetation of both algae and larger aquatic plants. Chara spp. abound, and the phytoplank- ton approaches the cyanophyte-diatom type. Near Post Lake is Elcho Lake, in which perch is the only game fish on record, and which has a poor phytoplanktonic flora and scarcely any larger vege- tation, as compared with Post Lake. [ 46 ] In general, the lakes in the southern sections have the physical- chemical qualities which permit the production of a bulk of vegeta- tion of all kinds greater than that of lakes in the central and northern regions. Hence the ultimate production of animal life is doubtless greater on the whole in the southern lakes, although there are few figures to support this. Crystal and Weber Lakes in Vilas County, and Clear Lake in Oneida County, Wisconsin, are notable examples of soft water lakes which are low in vegetation and are correspond- ingly poor producers of fish. Experimental studies have been made, and others are still in pro- gress, on the effect on ultimate faunal production of increasing the plankton by the addition of fertilizers. It has long been considered good practice in Europe to improve fish production in nursery ponds by this means, but few scientific evaluations have been made in this country. Wiebe, Radcliffe, and Ward (1929) report that in ponds to which fertilizers had been added, especially superphosphate, the microfauna and algae showed a great increase in numbers over con- trol ponds. (See also Ball, 1949.) Although the total quantity of plankton in a lake may be large, it is significant that the kind or quality of the plankters may be very important in regulating production of fish. There may be sufficient phytoplankton to support a rich microfauna on which fish feed. But if there is a paucity of intermediate feeders, such as minnows or other small predators, the food chain will thereby be interrupted, ‘om £ AWATER PANTS XS ‘i 61.5 Y Bx TER PLANTS Cee ale Figure 9. Diagrams illustrating the percentages of various types of food used by two species of turtles. Left: Percentages by volume of various foods consumed by western painted turtle (Chrysemys picta marginata). Right: Percentages by volume of various foods consumed by the snapping turtle (Chelydra serpentina). (Reproduced courtesy of Karl F. Lagler.) [ 47 ] for most of the larger fish cannot or do not feed directly upon the microfauna and flora. (See Fig. 3.) In addition to serving as food for the microfauna, either directly or indirectly, phytoplankton makes up a large part of the food con- sumed by several species of fish such as the gizzard shad, young suckers, black bass fingerlings, and certain mollusks. Recently I examined the alimentary tracts of several dozen snapping turtles and found that in nearly every instance they were heavily packed with algae and other plant fragments, to the exclusion of almost all other types of food. Spirogyra crassa, Cladophora sp., and Cerato- phyllum demersum L. were the principle plants eaten. Lagler (1940) has published on the food of the snapping turtle and points out that 36.2 per cent of the ingested material consisted of algae. He found that 70 per cent of all turtle specimens examined had con- sumed plant food. (See Fig. 9.) This is of interest because the snapping turtle had been considered almost entirely carnivorous. (See Lagler 1943. ) FACTORS THAT DETERMINE THE CHARACTER OF LAKE FLORAS A SUMMARY 1. The geological history of the region and the nature of the soil over which the lake lies or which is drained by inlets. 2. The depth of the lake and the shape of the bottom—V-shaped or U-shaped; presence or absence of shoals, shallow bays, etc.; extent of the epilimnion, location of the thermocline; completeness of the seasonal overturn. 3. Latitude; altitude (temperature and temperature range). 4. Relative amounts of oxygen and available carbon dioxide. 5. Nutrients in solution; salts; conductivity; pH; nitrogen content; phosphorus. 6. Nature of the bottom; bacterial flora; rate of overturn of or- ganic matter. 7. Biological enemies and competitors; parasites. 8. Chance distribution by agencies such as wind, waterfowl; isola- tion by barriers from other bodies of water. 9. Light; turbidity; color of the water; rate of diffusion of rays in- volved in photosynthesis. Because of the interrelationships and the complete interdepen- dence among some of the factors that determine the lake flora, it is obviously impossible to select any one as of paramount importance in a cause-effect analysis. Major interest here, however, is directed [ 48 ] toward phytoplankters and other chlorophyll-bearing organisms. As is well known these, both directly and indirectly, contribute food to the microfauna, which in turn provides nourishment for the benthic, limnetic, and emergent faunas. (“Emergent’ refers to the animal life which passes part of its life cycle in aquatic habitats, later emerging to join the land fauna.) In addition to their role in the food chain, chlorophyll-bearing organisms supply shelter and breeding places for many kinds of aquatic animals, and they also have important limnological bearings in that they alter the chemistry of the water, interfere with illumination, affect color, etc. Some of the phytoplankton (members of the Cyanophyta) are able to fix nitrogen and so affect the supply of nitrates and the nitro- gen cycle. Information on the nitrogen-fixing activities of the aquatic algae is meager, but evidence indicates that some forms play a more important role than is generally recognized in this connection. The quantity of phytoplankton is determined, in part at least, by the abundance of available carbon dioxide contributed by the atmos- phere, by half-bound carbon dioxide from bicarbonates, and from springs, etc. Carbon dioxide is, of course, continually being supplied also by respiration in all forms of life, including bacteria. At the same time all life draws upon dissolved oxygen, which diffuses from the atmosphere or is contributed as a result of photosynthesis. Other elements necessary for plants, such as phosphorus and nitro- gen, are supplied through drainage and by the continual overturn of organic matter by bacteria and other destructive organisms. Var- ious edaphic, limnological, and geological factors which determine water chemistry, contour of the bottom, and the presence or absence of seasonal overturns of lake water. These, in turn, help to determine the nature of the bacterial flora, and hence the kinds and amounts of decomposition products and the completeness with which the or- ganic matter is reconverted. Lakes and streams may receive run-off water from agricultural lands and effluents of waste matter which are richly supplied with critical nutritive elements and compounds. These become incorpo- rated in the food cycle. To an unknown extent, substances produced by bacterial decom- position also furnish nutrients to the microfauna. Also unknown is the extent to which nitrates for the use of green plants are formed by nitrifying bacteria. Information is not at hand which will permit a definite statement concerning this portion of the nitrogen cycle, but there is ample justification for assuming that nitrification by bacteria occurs under favorable aquatic conditions as it does in terrestrial soils. [ 49 ] MORPHOLOGICAL TERMS ILLUSTRATED PLANE SURFACES |] trapezoid subhexagonal quadrate oblong ovate ag lanceolate aaa rhomboid spatulate; truncate-spatulate [ 52 ] REGULAR SOLID ForMsS CPC id orbicular depressed globose ae obovoid oblong-ovate discoid i. pyramidal we Ble: cylindrical fusiform; naviculoid lenticular dolioform [ 53 ] IRREGULAR SOLID Forms as S 3 renif orm lunate sigmoid —_semilunate ane arcuate cordiform planoconvex ) pyriform G clavate i saccate panduriform [ 54 ] IS vermiform citriform ventricose terebriform TERMINAL FORMS AND STRUCTURES sagittate truncate uncinate rostrate; rostrate-capitate calyptrate [55 ] CHLOROPLAST FoRMS AND ARRANGEMENTS axial laminate radial CELL WaLL Forms AND STRUCTURES ) 4 plane cross walls replicate cross walls laminated walls colligate [ 56 ] SURFACE CHARACTERS SS la SOE VT ee ES %00090005> Tugose punctate 095000. 002 PSs © CO000m6 O° Se a ean CPALLOAON verrucose ST verrucae S S23 can a) reticulate costate plicate zonate [ 57 ] MARGINAL CHARACTERS crenate undulate dentate imcise convolute sinus [ 58 ] SHEATHS U . ’ , : o ’ 4 ° . . ° . a 8 » » . ‘ ts ° x . a : we 3 \ as : : a 0 : “i : S v Py : : e : * : e > . RQ . : . : : oS . . e : . 5 1 . . : . ~ . t . + . ‘= ‘ Hy e . . 5 . . a . . . “| Le . . s " 5 . 2 wie . . = ore . . ® .° . : . wile toe 5 ° 7 : sane ae : ~ ‘ re . . Vv . ’ . . . 4 . . : . . ° . © . . : confluent diffuent CELLULAR EXTENSIONS flagella rhizoids setae sheathed seta [59 ] BRANCHED FILAMENTS monaxial penicillate multiaxial intricate irregular [ 60 ] BRANCH CHARACTERS \P bilateral unilateral bifurcate dendroid adnate divaricate dichotomous [ 61 ] FmAMENTOUS COLONIES uniseriate multiseriate Boreee,, “tee, My . scalariform pseudofilamentous [ 62 ] circinate fliform flagelliform moniliform catenate caespitose [ 63 ] NON-FILAMENTOUS COLONIES 700000: (00000: 00000: 00000: 00000; rectilinear pulvinate clathrate Faligse lacunose [ 64 ] Systematic Account Structural terms are illustrated in the preceding section and are defined, together with other technical terms, in the Glossary. DIVISION CHLOROPHYTA Plants belonging to this group are characterized by grass-green chloroplasts, one to many in each cell or protoplasmic unit. In most forms the chloroplast contains one or more pyrenoids, which ac- cumulate starch as a food reserve. Even in plants which do not pos- sess a pyrenoid, presence of starch makes possible the use of the iodine test for separating doubtful forms from those Chrysophyta which are similar in general appearance. The cell wall, which is firm in most genera, is composed of cellu- lose and pectic compounds. There may be, also, a mucilaginous outer layer. ‘See G. M. Smith (1933, 1938) and F. E. Fritsch (1935) for a discussion of the reproduction and the taxonomy of this division; Collins (1909, 1918, 1918a) on the taxonomy; Blackman (1900), Blackman and Tansley (1902), and Fritsch (1916) on the phylogeny. The modern interpretation of this division recognizes two classes, Chlorophyceae and Charophyceae. CLASS CHLOROPHYCEAE This class, commonly known as the green algae, includes a great variety of forms: unicells (sometimes motile), simple or well- organized colonies, simple or branched filaments, partitioned coeno- cytes, and true coenocytes (filaments without cross walls). The chief evolutionary series in the Chlorophyceae begins with the motile uni- cells of the Volvocales. The methods of reproduction, both asexual and sexual, vary greatly within the several orders. In some orders, the sexual repro- ductive methods and organs are unique and serve as a basis for classification. This is particularly true for the Zygnematales (Con- jugales), the Oedogoniales, and the Siphonales. See the authors mentioned above, as well as Oltmanns (1922), for an account of reproduction and life histories in the Chlorophyceae. [ 65 ] Key to the Orders In the Keys, asterisks indicate orders, families, genera, or species that are likely to be found in the central Great Lakes region but have not been reported there to date. Ile 1. Motile in the vegetative condition; eee 2 or 4, ae 8, equal in length; organism 1-celled or colonial = 2 VOLVOCALES Not motile in the vegetative Gonditigii ae Aoi eel (Lhe 2 2. Cells embedded in copious mucilage (which is either homogeneous or 10. lamellated), united in colonies of indefinite shape (see Apiocystis, however ), or in tubes forming gelatinous strands (pseudofilaments ), or bullate masses (See mucilage-invested Chlorococcales also.); some forms unicellular or forming dendroid colonies which are epiphytic or epizoic; cells frequently possessing false flagella (pseudocilia), returning to a motile condition without resorting to reproductive (Se) | SR aneeiaedie ph iret Se ae ema Ce Oo) Eee TETRASPORALES ERE aTits FOL AS a bOVe wet. sae cane en Oe Ee ene ee eee eee 3 . Plants filamentous, composed of cells adjoined end to end in definite Series:sometimes, mterrupteds ss) 82. Uae stk Passa h ee Wn) CA Ne ee oe oe 4 - Plants not composed of cells arranged to form filaments; unicellular or colonial or, if filamentous, occurring as coenocytes without cross walls_15 . Filaments unbranched; attached or free-floating... 5 . Filaments with Beaneties! the branches sometimes closely appressed, form- ing spseudoparenchymatous iMmagees 2. Awe ee ee 13 . Filaments composed of a single series of cells_.-__-______-__-____- 6 . Filaments composed of more than | series of cells; cells adjoined; thallus a hollow tube or a ribbon-like or frond-like expansion 12 . Chloroplasts 1 to several, large, in the form of spiral bands, stellate masses, or broad plates; pyrenoids oe reproduction by conjuga- tion _ ae E3 _ZYGNEMATALES d Chloroplasts parietal, plate- aes nee likes or eal pads Se (in the latter case usually many in a cell); reproduction by iso- or heterogametes___. t . Cells with a single, parietal, plate-like or broadly discoid chloroplast; cells cylindrical; filaments uniseriate or multiseriate ULOTRICHALES 3 Gells: withyother ‘types vot chloroplasts =" == =a se ee eee 8 . Plants composed of long, cylindrical, coenocytic and thin-walled units, containing numerous disc-like chloroplasts arranged in narrow annular bands; cross partitions with knob-like thickenings; reproduction usually OOPAMNGUS A teates oo eS Pe See ad eet Dea ae SPHAEROPLEALES sa P lamtsenO tras a DOV Geet a a eee wes ieee ee) ee ee 9 . Cells cylindrical, ovate or subspherical, each surrounded by lamellate mucilage; frequently losing their uniseriate arrangement and forming palmella stages; chloroplast massive, filling the cell, obscured by many starch grains; sexual reproduction oogamous__...___. CYLINDROCAPSALES . Cells cylindrical, not surrounded by lamellate mucilage; chloroplast Parietal ot See ea MS Bate Dg Ci ied ua aa, ec ee 10 Cells with parietal, net-like or sheet-like chloroplasts, which usually cover both the end and lateral walls; wall composed of two sections which over- lap in the midregion, forming H-shaped pieces upon fragmentation; pyrenoids lacking; sexual reproduction unknown... MICROSPORALES [ 66 ] 10. Cells not showing H-shaped sections upon dissociation; pyrenoids present; sexual’ reproduction} kno Wn =e aeeee es eee) 1l 11. Cells coenocytic, cylindrical, with thick walls; chloroplast a dense, parietal net with pyrenoids at the intersections of the meshwork, or with many ovoid parietal discs; walls without ring-like scars at the anterior end of [een 6 =) | Gye Se Reece ee eee en kt Ves ls CLADOPHORALES (in part) 11. Cells not coenocytic, cylindrical but usually perceptibly larger at the an- 12. Plant an expanded plate or tubular strand formed by several series of cells; chloroplast a parietal plate similar to that in the Ulotrichales...."uLVALEs 12. Plant an expanded sheet, composed of several series of cells; chloroplast a Stellate qaxktal OOCyet nse 25 ee mee es se ta, __ *SCHIZOGONIALES 13. Filaments composed of cylindrical or rectangular, uninucleate cells which have a single, plate-like and parietal chloroplast; branches terminating in setae, or with cell walls bearing hairs or bristles which usually are not distinctly bulbousat the base: 2 CHAETOPHORALES 13?yPilaments notas ‘above ee SITE 1 alae 14 14. Filaments composed of cylindrical, coenocytic cells which may become attenuated toward their apices; setae and bristles wanting .________ Ree eeeeses | he ee ee _ CLADOPHORALES a(S AED) 14. Filaments composed of cells which are larger at the anterior end; bearing setae with much-enlarged, bulbous bases; reproduction oogamous, the female gametes produced in conspicuously swollen gametangia ale EPC sa Bit Pg 8 eo ee OEDOGONIALES (in part) 15. Plant composed of long, branched coenocytic strands without cross walls except where reproductive structures are cut off... SIPHONALES 15. Plant a single cell, or a colony of definite or indefinite form; cells various in shape, spherical, pyramidal, or polygonal, incapable of division in the vegetative state; reproduction by autospores, zoospores, or isogametes. (Compare with Tetrasporales, in which Chlamydomonas-like cells form colonies in mucilage that resemble some members of this order.) ____..... CHLOROCOCCALES ORDER VOLVOCALES In this order both vegetative and reproductive cells are motile. The prototype of the Chlorophyceae is to be found among the 1-celled members, from which colonial Volvocales, as well as other orders of green algae, are thought to have evolved. There may be 2, 4, or rarely 8 flagella. Usually there is a conspicuous pigment-spot. Although a few colorless forms are recognized, by far the majority of these organisms have a cup-shaped, parietal chloroplast (rarely stellate or axial) with one or more pyrenoids. Reproduction is by cell division, by zoospores (formed 2—8 in a cell), by isogametes, or by heterogametes, egg and antherozoids being formed in sexual reproduction among the more advanced colonial genera. [ 67 ] Key to the Families 1. Cells solitary, naked, i.e., inclosed only by a membrane; cell wall lack- 11) © eae eae een ce erees SAND Cane mmr re sn ask Ae el: 5 POLYBLEPHARIDACEAE 1. Cells possessing a definite wall and sometimes a mucilaginous sheath; Solitary or united inicolonies:=)2 252 Bt ee ie eed, 2 2enGellstsolitany' 23322 ee Ue ak eS 8 oe eee a A eS) Seen 8 2 Gellsmunited int colonies 222 * 2a st te ee ee oe ee 5 3. Wall bivalved, the cells compressed and the halves of the wall adjoined along their lateralimargins 92.3 ee * PHACOTACEAE 8: \Wallenot bivalved:' cells not fattened 3 eee 4 4. Cells with protoplasts located at some distance within the cell wall and connected to it by radiating cytoplasmic GERAIS: Peace. cee cece ere ete Se ecanrn ett HAEMATOCOCCACEAE (in part) 4. Cells without radiating cytoplasmic strands. CHLAMYDOMONADACEAE 5. Cells with many radiating cytoplasmic processes connecting the proto- plast with the cell wall................. Perce HAEMATOCOCCACEAE (in part) 5. Cells without such radiating protoplasmic processes _________-_---------_-- 6 6. Cells united to form flat or globular colonies, evenly dispersed, although sometimes closely arranged within colonial mucilage_______. VOLVOCACEAE 6. Cells compactly united in tiers of 4 with their anterior ends all directed the same way; gelatinous sheath lacking —.._._______. SPONDYLOMORACEAE FAMILY POLYBLEPHARIDACEAE The chief characteristic of this family of unicellular individuals is the lack of a cellulose wall, the protoplast being inclosed by a membrane only. The cells have 2-4-8 anterior flagella of equal length, with contractile vacuoles sometimes present at their bases. A red pigment-spot is normally present. The chloroplast varies in form among the different members; usually it is a parietal cup con- taining a pyrenoid. Of the 7 genera reported from North America only 1 is known from this region at present. PYRAMIMONAS Schmarda 1850, p. 9 Cells hemispherical or obpyriform, broadest at the anterior end, which is depressed and 4-lobed; 4 flagella attached in the apical depression, with 2 contractile vacuoles below their point of attach- ment. Chloroplast a parietal cup with a pyrenoid in the posterior portion. Pyramimonas tetrarhynchus Schmarda 1850, p. 9 Pl. 1, Figs. 1, 2 Cells pyriform with the anterior end conspicuously 4-lobed; fla- gella attached close together in the apical depression. Chloroplast a parietal cup with 4 lobes. Cell 12-18, in diameter, 20-28, long. Wis. [ 68 ] FAMILY CHLAMYDOMONADACEAE The unicellular organisms which compose this family have a smooth cellulose membrane in 1 piece. There are 2 or 4 flagella, equal in length, and 2-4 contractile vacuoles at the anterior end of the cell. In most forms the chloroplast is cup-shaped and contains 1 to several pyrenoids (posterior or scattered) and a red pigment-spot laterally placed, usually anterior. Members of this family should be compared with those of the Phacotaceae in which the cell wall is in 2 valve-like pieces that adjoin along the lateral margins; and with the Haematococcaceae, in which there are radiating protoplasmic processes extending from the cytoplasm to the cell wall. There are 10 genera of this family reported from the United States, but only 2 of these have appeared in our collections. Key to the Genera COUS With AAC Cline ae eet eeieee eee eS pa Ae ed Carteria Cells with 2) flagella st ped LU hy, ek LS Chlamydomonas CHLAMYDOMONAS Ehrenberg 1835, p. 288 Cells ovoid, ellipsoid, or spherical, sometimes with 1 or 2 apical papillae, from which the 2 flagella arise; often with a narrow or wide mucilaginous sheath. Chloroplast a dense, padded body occupying the entire cell, or a thin parietal cup (in a few species H-shaped or stellate); pyrenoids 1 to many, basal or bilateral and scattered; pigment-spot lateral and anterior, rarely median; 2-4 apical contrac- tile vacuoles usually discernible. Species of this genus have the habit of coming to rest, losing their flagella, and entering upon a quiescent phase. Vegetative cell divi- sion continues, ordinarily accompanied by the secretion of mucilage, so that amorphous gelatinous masses are formed which contain many nonmotile cells. This is known as the palmella stage. Unicellu- lar or colonial algae in which the cells are ovate or globose and which have cup-shaped chloroplasts (e.g., Gloeocystis) should be compared, in making identifications, with this palmelloid expression of Chlamydomonas. Key to the Species 1. Cells inhabiting the empty loricas of Dinobryon C. Dinobryonii uy Cells not inhabiting the loricas of Dinobryon—..._____._._.. 2 2s Gells with) axial pyrenoids, basal or median 3 2. Cells with 1 or more pyrenoids, lateral or scattered..........0.00.00.00.000.0000. whet | Se Cells without anvapicaly papilla. = 6 C. globosa Bepoellsawitind or more. apical papillae. 22-22 4 [ 69 } 4, Cells epiphytic, on the mucilage of Microcystis...» C. epiphytica 4. Cells not epiphytic on colonies of Microcystis 5. Cells globose, with 2 contractile vacuoles in thiel anterior, @niG-see sie nae DL eee eae Sa ee C. pseudopertyi oo Cells; ellipsoid’ or, 10 vate eset Oo. ME ie SUPER ee a ee ee a 6 Guibapillaxsharplyspomtedes ere. = = 1 ce We ee ace eceeeree aeen erat Went. C. Snowii 6. Papilla broad and truncate; cell often truncate and angular at the anterior end) 3 4) ae eee C. angulosa i, (Cellsewith.2 apical papillae: == 2222 eee C. sphagnicola i. \@ells without; papillae or with only 12s = eee ee eee 8 SiiG@ellsvellipsoidy withet oyrenoid = 2 sen C. mucicola 8. Cells ovate or cylindrical, with many pyrenoids fe) 9. Cells ovoid, without a papilla; pyrenoids many. W216). lateral: We. 2s ee C. polypyrenoideum 9. Cells cylindrical to subcylindrical, with a papilla; PY LEW OL Sie Wy na eeaeee ns Dees eet oa ae eee NL Ee ae Oe eee C. Cienkowskii Chlamydomonas angulosa Dill 1895, p. 337 PI Bigs3 Cells broadly ovoid to cylindric, often truncated anteriorly and with a prominent papilla. Contractile vacuoles 2, below the flagella, which are as long as or slightly longer than the cell body. Chloro- plast a massive, parietal cup with a large angular pyrenoid in the base; pigment-spot anterior and lateral. Cells 11-13-(15), in dia- meter, 15-18-20, long. Tychoplankter. Wis. Chlamydomonas Cienkowskii Schmidle 1903a, p. 349 Pl.1, Fig. 4 Cells cylindric to subcylindric with a prominent apical papilla, below which are 2 contractile vacuoles. Flagella shorter than the cell in length. Chloroplast a thin, parietal, cylindrical cup with several. pyrenoids. Pigment-spot anterior and lateral. Cells 10-11 in dia- meter, 20-25, long. Our specimens are shorter than usual for this species, but the shape of the cell, the form of the chloroplast, and the number of pyrenoids are in agreement. Tychoplankter. Wis. Chlamydomonas Dinobryonii G. M. Smith 1920, p. 91 PIV igo Cells ovoid to pyriform, without an anterior papilla, inhabiting the empty loricas of Dinobryon; flagella 6-8» long. Chloroplast disc- [ 70 ] shaped to hemispherical, lying either at the base of the cell or along the lateral wall; pigment-spot lacking (?). Cells 2-3, in diameter, 3-5y long. Rare to common in several lakes. Wis. Chlamydomonas epiphytica G. M. Smith 1920, p- 91 Plol, Figsi6,7 Cells spherical to nearly pyriform, anteriorly narrowed into a papilla-like beak. Cells becoming non-motile, adherent to the colon- ial mucilage of Microcystis without losing flagella. Chloroplast a thin parietal cup; pigment-spot lacking. Cells 7-8. in diameter, 8-9u long. Common in several lakes. Wis. Chlamydomonas globosa Snow 1903, p. 389 BLAS Wigs. 8.9 Cells broadly ovoid to globose, inclosed in a hyaline, gelatinous sheath; anterior papilla absent. Chloroplast a dense parietal cup with a basal pyrenoid; 1 contractile vacuole in the anterior end of cell; pigment-spot lens-shaped, supramedian in position and lateral. Cells 5-7, in diameter, 10-19, long. Tychoplankter; common. Mich., Wis. Chlamydomonas mucicola Schmidle 1897a, p. 17 Pl. 46, Fig. 20 Cells narrowly elliptic or narrowly ovoid, attenuated to a blunt point anteriorly, broadly rounded posteriorly. Flagella 114 times the body in length. Chloroplast a lateral plate with a single large pyre- noid; pigment spot and 4 contractile vacuoles in the anterior end. Cells 3-4, in diameter, 6-10, long. Tychoplankter. Mich. Chlamydomonas polypyrenoideum Prescott 1944, p. 348 PUA Figs, 10.11 Cells ovoid to ellipsoid, without an apical papilla; gelatinous sheath lacking (?). Chloroplast a dense parietal cup with a deep median invagination; pyrenoids many (12-16), scattered; pigment- spot not observed. Cells 8-10 in diameter, 9-12» long. Rare in euplankton. Wis. [71] Chlamydomonas pseudopertyi Pascher 1927, p. 214 Blah ig 2 Cells globose, with a prominent, hemispherical papilla. Chloro- plast cup-shaped, dense in the basal portion; 2 anterior contractile vacuoles; pyrenoid posterior; pigment-spot lens-shaped, anterior and lateral. Cells 12-18—(27), in diameter. Tychoplankter; rare. Wis. Chlamydomonas Snowii Printz 1914, p. 18 Pl. 1, Figs. 13, 14 Cells narrowly ovoid to ellipsoid, with an anterior beak. Chloro- plast a parietal cup, dense in the posterior portion; 1 pyrenoid, centrally located, palmella stages frequent. Cells 6.5-8» in diameter, 10-15, long. Tychoplankter; rare. Mich., Wis. Chlamydomonas sphagnicola Fritsch & Takeda 1916, p. 373 Pl. 1, Figs. 15, 16 Cells broadly ovoid to subglobose, broadly rounded both anteriorly and posteriorly, with 2 prominent papillae at the anterior end; the protoplast separated from the wall, also having pointed apical papil- lae. Chloroplast a parietal sheet, granular, covering most of the cell membrane (in our specimens more dense toward the basal part); pyrenoids several (4-6), scattered; pigment-spot prominent, anter- ior, nearly median. Cells 15-18, in diameter, 21-29, long. This species commonly forms resting stages during which 2-4 cells are formed within the old mother cell. Common in Sphagnum bogs; tychoplanktonic in lakes. Wis. CARTERIA Diesing 1866, p. 356 Cells oval or round in cross section, elliptic, oval, or cordiform in front view, with a definite cell wall; furnished with 4 long flagella. Chloroplast parietal, cup-shaped, with or without a pyrenoid; pigment-spot usually present, at the anterior end of cell. Species in this genus should be compared carefully with Chlamy- domonas spp. Carteria in the past has been placed in a separate fam- ily (Carteriaceae), mostly on the basis of the number of flagella. Only 2 species have appeared in our collections. Key to the Species Cells cordiform, broadest at the anterior end, Awihich: is: CONCAVG =.= eres ee) es ee C. cordiformis Cells ellipsoid or ellipsoid-cylindric, narrower, and papillaterat. the anterioniend == ee C. Klebsii Carteria cordiformis (Carter) Diesing 1866, p. 356 PI. 1, Fig. 20 Cells cordiform, broadest at the anterior end, which is deeply de- pressed, the 4 flagella arising within the depression; somewhat smal- ler but broadly rounded posteriorly. Chloroplast a thin parietal cup, with 1 basal pyrenoid. Cells 16, in diameter, 12-20, long. Rare in tychoplankton. Mich., Wis. Carteria Klebsii (Dang.) Dill 1895, p. 353 Pl. 1, Figs. 17-19 Cells ellipsoid or ellipsoid-cylindric, narrower at the anterior end, which is sharply rounded with a papilla around which the flagella arise. Chloroplast a massive parietal cup, with 1 basal pyrenoid; pigment-spot lacking. Cells 5-10y in diameter, 8-16, long. Rare in tychoplankton. Wis. FAMILY PHACOTACEAE The flattened, unicellular biflagellates of this family, with their two-valved walls, especially Phacotus lenticularis (Ehrenb.) Stein, and Pteromonas angulosa (Carter) Lemm., are to be expected in the central Great Lakes region, but no member of the family has appeared in our collections. FAMILY VOLVOCACEAE Members of this family are colonial. The cells are characteristically biflagellate and Chlamydomonas-like and are so arranged as to form globose or obovoid hollow colonies or flat plates. There may be as few as 4, or as many as 25,000, cells in a colony. Cell sheaths may be distinct or confluent with the colonial mucilage. In most genera the cells of the colony are alike in size and func- tion, but in the more advanced forms there is a certain amount of specialization. In Pleodorina, for example, a few of the cells are dis- tinctly smaller than others and have no reproductive function. In Volvox some cells enlarge and become female gametes, whereas others undergo division to form plates of numerous, small anthero- zoids. Both kinds of gametes may be produced in the same colony (monoecious) or in separate colonies (dioecious) according to spe- cies. See Smith (1933, 1938, 1944), Fritsch (1935), and Pascher (1927) for the morphology, reproduction, and taxonomy of this family. [ 73 ] Key to the Genera le* Wolony/sphericaliorsGyoid 229 )8. 21s et ed ge) 2 1. Colony a flat or twisted plate with cells in 1 layer___-_-____ 5 2. Colony spherical, ovoid, or obovoid, containing 256 or fewer cells 8 2. Colony a hollow sphere, containing from 500 to several thousand cells wm be lauretee Lars i ihe 1S eal ee SM Dye NA RUN hee Volvox 3. Colony containing from (32)—64 to 256 cells, which are of 2 SIVA SNA en eg ees ote eg PRE Ren i ae aces ak Sek ee ad Pe Re A SE Pleodorina 3. Colony containing less than 64 cells, all similar in size_t 4 4. Colony ovoid or obovoid, composed of spherical or ellipsoid cells arranged at some distance from one another and often appearing in transverse tiers _ ___. Eudorina 4, Colony ovate, composed of pyriform cells compactly ‘arranged _ = Pandorina 5. Colony a flat, rectangular plate of from 4 to 32 cells Gonium 5. Colony horseshoe-shaped, slightly twisted on its Axis MCOMPOSECLO lel GNOIaa Cel IS eee eon ee Ee *Platydorina GONIUM Mueller 1778; emend. Prescott in Prescott, Silva, & Wade 1949, p. 84 A free-swimming, plate-like, quadrangular colony of 4-32 ovate, ovoid, pyriform, or bilobed cells so arranged within a gelatinous envelope that a rectangle of 4-8 central cells is inclosed by a periph- eral series of 12-24 individuals; the long axis of the central cells at right angles to the plane of the colony, but axis of peripheral cells radial to the center of the colony. Cells interconnected by fine proto- plasmic processes; individual envelopes adjoined by stout processes with those of neighboring cells, so that oval or quadrangular inter- stices are formed in the colonial mucilage. Flagella 2, attached in the narrow anterior end just above 2 contractile vacuoles. Chloro- plast a parietal cup with 1 or 2 pyrenoids; pigment-spot usually large and conspicuous, lying laterally in the anterior end. Sexual repro- duction by the division of the vegetative cells into 4-16-(382?) iso- gametes which fuse in pairs, the quadriflagellate zygote becoming a thick-walled resting spore. Key to the Species 1. Colony 4-celled, with anterior ends of cells all directed outward __ G. sociale 1. Colony 16-32-celled (rarely 4-celled); the outer cells with flagella directed in the transverse plane of the colony, the inner cells with flagella directed at right angles) to: the:trausverse plane. 5 <0) 22.3 2 ees 2 2, Cellsvellipsoid Or;subsphericalest ss. e See teaees eee ee G. pectorale 2. Cells ovoid-pyriform, narrowed anteriorly... G. formosum Gonium formosum Pascher 1927, p. 418 Colony of 16 ovoid-pyriform cells inclosed in relatively wide indi- vidual sheaths which are joined to neighboring sheaths by narrow and relatively long arm-like extensions so that each of the inner 4 [74 ] cells is connected with 6 other cells, leaving a large circular open space in the center of the plate. Chloroplast a parietal cup, thickened at the base, which incloses a pyrenoid; pigment-spot anterior and lateral. Cells about 10, in diameter, 1-114 times as long as wide. Mich. Gonium pectorale Mueller 1773, p. 60 PI. 1, Fig. 21 Colony of (4)-8-16 ellipsoid, subspherical or sometimes ovoid cells closely arranged in a flat, quadrangular plate, usually with 4 inner cells bordered by a series of 12 marginal ones which have their anterior ends projected outward and parallel with the plane of the colony, the inner cells directed at right angles to the plane. Cells inclosed by individual sheaths, which are connected to neighboring sheaths by very short processes. Cells 5-15 in diameter. Associated with other Volvocales in hard water rich in nitrogen. Mich., Wis. Gonium sociale (Duj.) Warming 1876, p. 82 Pl. 1, Fig. 22 Colony of 4 ovoid cells, all directed outward, inclosed by colonial mucilage which has a central rectangular perforation. Cells 10-15. in diameter, 12-20, long. This species, like G. pectorale, is often found in barnyard pools, watering troughs, and sloughs where nitrogen content is high. Eu- and tychoplanktonic; in hard water lakes. Mich., Wis. PANDORINA Bory 1824, p. 600 Colony ovate or obovoid, composed of 8-16—(32) globose or pyri- form cells compactly arranged and inclosed by a common gelatinous envelope; cells with the broad anterior end directed outward. Chlor- plast a parietal cup with 1 basal pyrenoid; pigment-spot anterior and lateral. Flagella 2, arising from the anterior end of the cell and diverging widely after emerging from the colonial envelope; the colony swimming in a rolling or tumbling fashion; vegetative re- production by the simultaneous division of each cell in the colony to form as many colonies; sexual reproduction by isogametes formed in groups of 8 or 16 by the partition of some or all of the cells of the colony. Pandorina morum (Muell.) Bory 1824, p. 600 Pl. 1, Fig. 23 Colony usually distinctly ovate, as much as 220y in diameter. Cells pyriform, crowded, usually 16 in number, 10—15y in diameter, 12-17». long. [75 ] Common in the plankton of both hard and soft water lakes but more frequent among dense growths of algae in shallows, especially in water rich in nitrogenous matter. Mich., Wis. EUDORINA Ehrenberg 1832b, p. 78 A free-swimming ovate, obovoid, or globose colony, in which 16-32-64 ovoid or ovate cells are inclosed within a gelatinous en- velope. Cells sometimes arranged in transverse series, sometimes evenly disposed throughout the colonial mucilage; 2 long flagella present, which diverge widely beyond the periphery of the colonial envelope; cells often with 1 or 2 anterior beaks or papillae where the flagella arise; 2 minute contractile vacuoles at the base of the flagella. Chloroplast cup-shaped and parietal, with 1 to several pyre- noids. Red pigment-spot laterally placed at the anterior end of the cell. Cytoplasmic strands connecting the cells sometimes in evidence. Anisogamous sexual reproduction by small antherozoids and _bi- flagellate female gametes similar in size to vegetative cells. Eudorina elegans Ehrenberg 1882b, p. 78 Pl. 1, Figs. 24-26 Colony spherical or ovate with 16-82 ovoid cells evenly disposed within a gelatinous envelope, or arranged in transverse series, the cells usually lying near the periphery of the envelope but sometimes crowded toward the interior. Cells 10-20, in diameter; colonies up to 200u in diameter. This species shows a great deal of variation in the size and shape of the colony. In liquid-preserved material the envelope shows the form of E. unicocca G. M. Smith, with posterior mammillate pro- jections. Common in euplankton of hard water lakes. Mich., Wis. PLEODORINA Shaw 1894, p. 279 A free-swimming globose colony of 32-128 (rarely 256) spherical or ovoid cells arranged at the periphery of a gelatinous colonial in- vestment. Cells differentiated and of 2 sizes, the purely vegetative (toward the posterior pole) being about half the size of the repro- ductive (anterior) cells. Chloroplast a parietal cup, with 1 or more basal pyrenoids. Pigment-spot lateral and anterior. Flagella, 2, at- tached at the anterior end of cell, just above 2 contractile vacuoles; the colony swimming in a rolling or tumbling fashion. Sexual repro- duction anisogamous. [ 76 ] Key to the Species Colony with 64-128 cells about half of which are smaller anGy vegetative. =e es eee en ee nk P. californica Colony with 32-64 cells, only 4 of which are Smiallensands vecetacives <2 2s tek eee ea P. illinoisensis Pleodorina californica Shaw 1894, p. 282 Pl. 2, Fig. 1 Colony spherical, containing as many as 128 globose cells, about half of them vegetative and half reproductive in function, the latter distinctly larger than the former. Flagella subparallel within the mu- cilage, diverging widely outward. Vegetative cells 6-14 in diam- eter; reproductive cells up to 34u in diameter. Rare in the plankton of several lakes; occasionally abundant in water rich in organic matter. Mich., Wis. Pleodorina illinoisensis Kofoid 1898, p. 274 [Eudorina illinoisensis (Kofoid) Pascher] Pl. 2, Fig. 8 Colony globose, containing 32-64 cells, 4 of which are small and vegetative, and located toward the posterior pole of the colony. Vegetative cells 8-10 in diameter; reproductive cells 14-20u in diameter. Rare; found in a fish hatchery pond. Wis. VOLVOX Linnaeus 1758, p. 820 Colony free-swimming, spherical or ovate, composed of from 500 to several thousand cells arranged at the periphery of a gelatinous sphere of homogeneous mucilage, in which, however, the individual cell sheaths may be distinct; the cells all directed outward and each having 2 flagella of equal length. In some species, the cells are inter- connected by protoplasmic strands or ‘canals’. Chloroplast a parietal incomplete cup covering most of the cell wall. Daughter colonies form within the interior of the sphere by repeated division of special gonidial cells which have withdrawn from peripheral layer. Sexual reproduction oogamous; female gametes large spherical cells within the sphere; male gametes spindle-shaped, formed in several to many rectangular plates or bundles in the interior of the colony, the antherozoids with their longitudinal axes at right angles to the surface plane of the plate. Zygote thick-walled, smooth, or bearing external decorations such as spines and warts. ecicea Key to the Species 1. Colony of from 8000 to 17,000 cells which are angular, polygonal. or stellate iiend view) == ee V. globator 1. Colony with fewer cells than above; cells round in end view_.-_____. 2, 2. Colony of 1800-3200 cells which are not inclosed by TMNCUVAGl altars la eal thn gees ee ee La kL al ee V. aureus bo . Colony smaller, 500-2000 cells, inclosed by individual sheaths V. tertius Volvox aureus Ehrenberg 1838, p. 71 Pl. 2, Fig. 4 Dioecious (rarely monoecious), spherical colonies of (500)- 1300-3200 ellipsoidal cells, 4-6. in diameter, with interconnections of fine protoplasmic strands; individual cell sheaths wanting. Strands of mucilage radiate from the center of the colony. Cells contain a circular, parietal plate-like chloroplast, with 2 contractile vacuoles at the anterior end, below the point of flagella attachment, and a pigment-spot, anterior and lateral. In mature coenobia, 2 or more daughter colonies are present. As many as 21 (usually about 9) eggs are formed in female colonies; half of the cells in male coenobia develop antherozoid bundles, 15-18, in diameter, with as many as 32 antherozoids in each bundle. Zygote 38-62, in diameter, with a smooth wall. Common in the plankton of many lakes; sometimes abundant in shallow, backwater habitats; also found in inlets to lakes where water is slow-flowing or pooled. Mich., Wis. Volvox globator Linnaeus 1758, p. 820 Pl. 2, Fig. 5 Large, monoecious, spherical or ovate, gelatinous colonies contain- ing as many as 17,000 ovoid or pyriform cells. Cells 2.5-3.5p in di- ameter, with conspicuous protoplasmic interconnections; with 1 parietal plate-like chloroplast and a pigment-spot in each cell, and with 2-6 small contractile vacuoles in the anterior region below the point of flagella attachment. Individual sheaths of the cells conspic- uous and not confluent with the colonial mucilage, clearly visible in surface view of the colony, the sheaths 5-8-sided from mutual com- pression. Coenobium commonly containing 4-7 (or as many as 17) daughter colonies; sexual colony with 11-17, or up to 40, eggs, each inclosed by a wide gelatinous sheath; 3-7 rectangular plates of fusi- form antherozoids in bundles of 64-256, 22-32 in diameter. Zy- gotes 45-54, in diameter, with thick walls exteriorly decorated with wart-like, blunt spines and verrucae. [ 78 ] Although not uncommon in the plankton of lakes, this species is most frequently found in the shallow water of bogs, ponds, and ditches especially where the nitrogen content is high; also in hard water habitats. Mich., Wis. Volvox tertius A. Meyer 1896, p. 188 [Volvox mononae G. M. Smith] Pl. 3, Fig. 12 Dioecious, relatively small colonies, 280-550. wide, 302-590. long, spherical to ellipsoidal, containing 500-2000 ovoid or ellip- soid cells without interconnecting protoplasmic strands, but with individual sheaths which sometimes are scarcely evident. Cells 5-8, in diameter. Chloroplast parietal, cup- or bell-shaped; pigment- spot anterior and lateral; 2 (sometimes more) contractile vacuoles below the point of flagella attachment. Mature coenobium contains 3-10-(12) daughter colonies. Eggs, 3-8 large globose cells inclosed by a gelatinous sheath; antherozoid bundles 20-60 in number, con- sisting of 16-32 (sometimes as many as 64) fusiform antherozoids; zygotes 58-66, in diameter, with a thick, smooth wall. This species is reported from Lake Monona, Wisconsin (Smith, 1920). In Iowa (Prescott, 193la) it was found in one of the semi- hard water lakes, forming a dense bloom, which endured for two or three days in late summer when the water temperature was high (28°C.). Mich., Wis. FAMILY SPONDYLOMORACEAE In this family the cells are compactly arranged in small colonies of 8 or 16 individuals with their long axes parallel and all directed forward. There is no colonial mucilage. The chloroplast is a dense, parietal cup without a pyrenoid except in the genus Pascheriella Korshikov (not represented in our flora). There are 2 or 4 flagella, 2 contractile vacuoles in the anterior re- gion, and a pigment-spot, either anterior or posterior. See Fritsch (1934) and Smith (1938) for a discussion of reproduction in this family; also Korshikov (1923, 1924, 1928). SPONDYLOMORUM Ehrenberg 1849, p. 236 Colony ovoid, of 8 or 16 pyriform cells compactly arranged in tiers without an evident gelatinous investment; the cells with their broad apices all directed anteriorly, and having 4 long flagella which [ 79 ] arise from a conical protuberance, at the base of which are 2 con- tractile vacuoles. Chloroplast cup-shaped, without a pyrenoid; pig- ment-spot lateral and posterior. Spondylomorum quaternarium Ehrenberg 1849, p. 236 Pl. 3, Figs. 1, 2 Cells narrowed and somewhat produced posteriorly to form blunt- ly rounded points, 5-15, in diameter. Colony 36-75y in diameter. Reported by Stickney from a laboratory aquarium in Madison; to be expected in the plankton of lakes rich in nitrogenous substances. Wis. FAMILY HAEMATOCOCCACEAE In this family the cells are peculiar in that the protoplast lies some distance within the cell wall, to which it is connected by fine proto- plasmic strands. Between the wall and the protoplast there is a wide layer of mucilage. There is a massive chloroplast, which in Sphae- rella is usually masked by an abundance of haematochrome, a red pigment which develops when the cell is dormant. There are 2 fla- gella, several contractile vacuoles, and a lateral pigment-spot. Key to the Genera Welispesp litany cece seus e, sony teem aie) cts A etn ence Haematococcus Cells in colonies, forming a circumferential band in a spheroidal gelatinous’ investment... .- = Stephanosphaera Haematococcus C. A. Agardh 1828, Icon. Algar., Pl. 22. Cells ovoid to ellipsoid, having 2 widely diverging flagella from an anterior papilla; protoplast separated from the wall by a wide en- velope of mucilage through which cytoplasmic strands radiate; pigment-spot lateral. Cells frequently appearing in a stationary (akinete) condition in which haematochrome pigment becomes pre- dominant (assumed to be an adjustment to intense illumination, especially when the water is shallow). At least 1 species of the genus has been reported from red snow of alpine and subalpine regions. Haematococcus lacustris (Girod.) Rostafinski, 1875, p. 139 Sphaerella lacustris (Girod.) Wittr. Pl 2 Fig. 2: Pl. 3, Figs. 3-5 Cells ellipsoid or ovoid; chloroplast apparently cup-shaped, some- times appearing axial and usually masked by haematochrome; cells variable in diameter, 10-50 in the encysted condition. [ 80 | This species is usually found in small pools, crevices in rocks hold- ing rain water, and in concrete basins of various kinds. A familiar habitat is the bird-bath in gardens. Because intermittent drying of the habitat keeps this plant in a dormant condition most of the time, it usually appears as a brick-red, slimy or granular encrustment on the substrate. Mich., Wis. STEPHANOSPHAERA Cohn 1852, p. 77 A colony of 4-8 ovoid cells with branched (both lateral and polar) protoplasmic extensions, arranged in a median circumferential band within an oblate-spheroid colonial mucilage. Cells free from, and some distance from, one another, not connected by protoplasmic extensions. Flagella 2; pigment-spot lateral, near the anterior end of cell; chloroplast parietal and usually dense, with 2 or more pyre- noids. Stephanosphaera pluvialis Cohn 1852, p. 77 Pl. 46, Fig. 26 Characteristics as described for the genus. Cells 7-12.5, in diam- eter; colony up to 60, in diameter. Reproduction by isogametes. Zygote up to 28u in diameter. Michigan. ORDER TETRASPORALES! Plants belonging to this order are essentially volvocaceous, but they are nonmotile in the vegetative condition. Some forms are free- floating, but many are sedentary. The volvocaceous characters are pseudocilia (non-functioning flagella), the pigment-spot, and the type of chloroplast. All of the features may not be exhibited by all members. Most forms are colonial, with the cells embedded in copious mucilage, but there are unicellular genera. It is easy to confuse some of the small free-floating colonies with certain plants belonging to the Chlorococcales. Differentiation must be made by considering a combination of characteristics and the type of repro- duction used. The Tetrasporales are able to reproduce freely by cell division in the vegetative state, but the Chlorococcales are all in- capable of this method of reproduction. In general, the chloroplast in the Tetrasporales (Asterococcus excepted ), is a parietal cup (see Elakatothrix, however), with a single pyrenoid. In the Chlorococ- cales it is nearly always a parietal plate or sheet, not a Chlamydo- monas-like cup. 1Some authors, Fritsch (1935), Pascher (1927), for example, treat the Tetrasporales as a suborder of the Volvocales. [ 81 ] Key to the F amilies 1. Cells solitary or in false dendroid colonies, attached by stalks or fine thread-like stipes to larger algae and microfauna_________ CHLORANGIACEAE 1. Cells not as above; free-floating or adherent_—_______-______ 2 2. Cells ellipsoidal or fusiform_ COCCOMYXACEAE 2. Cells spherical —_------—-—------ 3 3. Cells bearing pseudocilia (frequently discerned only with difficulty ); usually united in definitely shaped gelatinous colonies, macroscopic or microscopic; individual cell sheaths rarely present and if present may be scarcely visible__----—----—----—--------------------- TETRASPORACEAE 3. Cells not bearing pseudocilia; solitary or united in amorphous gela- tinous masses; individual cell sheaths usually clearly visible _PALMELLACEAE FAMILY PALMELLACEAE These plants have spherical or ovate cells united in amorphous or sometimes definitely shaped colonies. Individual cell sheaths (if present) are clearly evident and are usually lamellate. Although some colonies are spherical and free-floating, others are tubular or bullate and adherent, or entangled among other algae. In one genus ( Asterococcus ) the chloroplast is stellate, but in general it is parietal and cup-shaped. In 2 genera the sheaths are much lamellated and are deposited as mucilaginous secretions about the cell more on one side than on others so that the cell comes to lie excentrically in the investment. Sometimes this may result in the formation of branched, gelatinous strands. Key to the Genera Iea@ells solitary ae 2 1. Cells arranged to form colonies or families which may be definite or indefinite in shape 8 2. Cells with a stellate chloroplast or with radiating strands from a GOI OME CEIMLCT ese 2 ae alr a ee ee Asterococcus (in part) 2. Cells with a cup-shaped, parietal chloroplast____________-- Gloeocystis (in part) (see also Urococcus ) 3. Cells grouped to form amorphous colonies 4 3. Cells grouped to form colonies of definite shape, spherical clusters, or tubular arrangements _______----------——-------——--—--—-----~-—=== 5 4. Colonies of macroscopic size, amorphous masses, adherent; cells single or in pairs within a copious mucilage; cell sheaths confluent... Palmella 4. Colonies of microscopic size; cell sheaths definite, usually lamellate-=1 i) Lied 8 ee Gloeocystis (in part) 5. Colonies -spherical________-____-_____-___>__ 6 5. Colonies elongate and tubular, forming false filaments. Palmodictyon 6. Chloroplasts stellate ____--------------------------------------- Asterococcus (in part ) 6. Chloroplasts parietal a 7. Sheaths of cells definite, often lamellated; colonial mucilage Vari ates fh ee aug ah eA Gia te aS Gloeocystis (in part) 7. Cells without sheaths, colonial mucilage homogeneous ___----- Sphaerocystis [ 82] PALMELLA Lyngbye 1819, p. 203 A shapeless, gelatinous mass, containing many spherical cells with- out any order of arrangement; individual cell sheaths usually dis- tinct at first, becoming confluent with the colonial mucilage. Chloro- plast cup-shaped or bell-shaped, with 1 pyrenoid. Plants aquatic or terrestrial. Palmella mucosa Kuetzing 1848, p. 172 Pl. 3, Figs. 8, 9 Plant mass densely green, forming gelatinous expansions on the substrate; individual cell sheaths evident at first but becoming in- distinct; chloroplast parietal, covering nearly the entire wall; cells 6-14, in diameter. On submerged logs, aquatic plants, and other substrates; frequent- ly on wet rocks, on sides of aquaria, or on cement basins. Wis. SPHAEROCYSTIS Chodat 1897, p. 119 A free-floating spherical colony of from 4 to 32 spherical cells, evenly spaced near the periphery of a non-lamellate gelatinous en- velope, sometimes with a sheath about each group of 4 cells within the colony. Chloroplast cup-shaped and covering most of the wall, containing | pyrenoid. Sphaerocystis Schroeteri Chodat 1897, p. 119 Pl. 3, Figs. 6, 7 Colony often including both undivided and recently divided cells which form small spherical clusters within the colonial envelope. Cells 6-20, in diameter; colonies up to 500, in diameter. This plant should be compared with Planktosphaeria gelatinosa. Widely distributed and common in a variety of lakes, both hard and soft water. Mich., Wis. GLOEOCYSTIS Naegeli 1849, p. 65 Cells spherical, sometimes solitary, but usually grouped in colonies of 4, 8, or many individuals inclosed by a colorless gelatinous en- velope, which may be globose or somewhat amorphous, lamellate or (rarely) homogeneous. Chloroplast parietal, cup-shaped, but often covering the entire wall, obscured by numerous starch grains or oil bodies; 1 pyrenoid. This genus should be compared with Sphaerocystis and Planktosphaeria. [ 83 ] Key to the Species 1.Cells oblong ‘or ovate*<= 2 Se >a) See 2 1. Cells, spherical 2. eee 8 2. Colony triangular or pyramidal; individual cell sheaths distinct and “much lamellated Ses ee G. planctonica 2. Golony.ovate oF aMmorphOuse == 225 ee ee 4 3. Colony spherical, usually of 8 cells (sometimes solitary), the colonial mucilage and cell sheaths regularly lamellate______________. G. gigas 3. Colony amorphous, forming irregularly expanded, jelly-like masses, often attached; colonial mucilage lamellate_.______________________ G. vesiculosa 4. Cells many in a colony; individual cell sheaths distinct, angular frommutual compression, not lamellate=: == a es G. ampla 4. 1Cells) few inva colony; sheaths lamellate=— == = G. major Gloeocystis ampla (Kuetz.) Lagerheim 1883, p. 63 Pl. 3, Fig. 17 Cells ovoid or oblong, arranged in amorphous or somewhat globu- lar colonies and embedded in copious unlamellated gelatinous en- velopes, the sheaths of each cell or group of cells not confluent but distinct and angular from mutual compression. Cells 9-lly in diameter, 10-14 long; colonies up to 150p in diameter. Common in the tychoplankton of many soft water lakes and acid swamps. Mich., Wis. Gloeocystis gigas (Kuetz.) Lagerheim 1883, p. 63 Pl. 3, Fig. 16 One-celled or a colony of § spherical or slightly oblong individuals inclosed by a copious, gelatinous, lamellate envelope. Contents of the cell frequently brownish-green because of oil. Cells 9-12, in diameter. Forming gelatinous masses on submerged aquatics or entangled among other algae. Common in the tychoplankton of many lakes and swamps. Mich., Wis. Gloeocystis major Gerneck ex Lemmermann 1915, p. 35 Pl. 52, Figs. 9, 10 Cells ovoid, in colonies of 4-8, inclosed by a wide, lamellate sheath in which groups of individuals are surrounded by concentric layers; Chloroplast massive, completely covering the wall; cells 17-19, in diameter, 21-23, long. Tychoplankter; in hard water lakes. Wis. [ 84 ] Gloeocystis planctonica (West & West) Lemmermann 1915, p. 34 Pl. 3, Figs. 10, 11 Cells spherical or ovoid, united in free-floating gelatinous colonies which are angular or pyramidal. Sheaths of each cell or group of cells distinct and lamellate. Cells 4-13, in diameter; colonies up to 125 wide. Common in the littoral plankton of shallow lakes and ponds; inter- mingled with other algae. Mich., Wis. Gloeocystis vesiculosa Naegeli 1849, p. 66 Pied, Bigals Cells spherical, arranged in large amorphous masses (usually at- tached), inclosed by copious lamellate mucilage. Cells 4.5-12 in diameter. Commonly intermingled with other algae in bogs and shallow lakes; on submerged aquatics. Mich., Wis. PALMODICTYON Kuetzing 1845, p. 155 Thallus an anastomosing or irregularly branched gelatinous strand, inclosing families of globose cells with individual mucilaginous sheaths. Frequently several generations of cells are within a common investment. Chloroplast a parietal plate covering most of the cell wall, with 1 pyrenoid. Key to the Species Cells without evident individual sheaths ess P. varium Cells with distinct individual sheaths. 2-9 P. viride Palmodictyon varium (Naeg.) Lemmermann 1915, p. 37 Pixs Figs. 3,4 Thallus a simple or branched gelatinous strand, often many such tubular strands radiating from a common center, containing spheri- cal cells without evident sheaths in linear series or irregularly crowd- ed. Cells 4-8 in diameter; thallus 20-50, wide. Entangled among dense growths of algae on submerged aquatics in soft water lakes. Mich., Wis. Palmodictyon viride Kuetzing 1845, p. 155 Pl. 4, Figs. 5, 6 Thallus a branching and anastomosing gelatinous strand or cylin- der in which families of globose cells are arranged in groups of 2-4 within a mucilaginous sheath. Cells arranged in 1 or 2 linear series, [ 85 ] with distinct, sometimes lamellate sheaths. Cells 5-10, in diameter; thallus 15-17, wide. Not common in shallow water of acid lakes; among other algae in tychoplankton. Mich., Wis. ASTEROCOCCUS Scherffel 1908, p. 762 Cells globose or subglobose, either solitary or in colonies of from 4 to 16, in colorless homogeneous envelopes of mucilage. Chloroplast 4 stellate mass with radiate arms from a central core, which contains a pyrenoid. The shape of the chloroplast assists in differentiating this genus from similarly shaped and arranged species of Gloeocystis. ts (Celliwallsispiny = = Pe ss FE LET 8 SCR ie 28 he A. spinosus Te Gelll-walls: smooth 2-2 ee 2. Cells solitary or in colonies of 4, 836-43 in diameter... A. superbus 2. Cells in colonies of 8 or 16, 10-25. in diameter —...........____. A. limneticus Asterococcus limneticus G. M. Smith 1918, p. 627 Pl Ay Bigs Cells spherical, arranged at some distance from one another in free-floating colonies of 4-16 within a colorless homogeneous invest- ing mucilage. Chloroplast stellate with 4-16 lobes radiating from a central core, the lobes becoming flattened against the cell wall. Cells 10-25-(35)» in diameter; colonies 50-125» in diameter. Common, usually in soft water. Mich., Wis. Asterococcus spinosus Prescott in Prescott, Silva, & Wade 1949, pp. 85, 93 Pl. 46, Figs. 17, 18 Cells spherical, solitary, or 2 within a gelatinous sheath, the cell wall thin and evenly beset with long, slender sharp spines. Chloro- plast with numerous (more than in other species ) narrow, radiating strands. Cells 12-16, in diameter. In shallow water of an acid lake. Mich. Asterococcus superbus (Cienk.) Scherffel 1908, p. 762 Pl. 4, Fig. 10 Cells spherical, solitary, or in families of 4-8 inclosed by a lamel- late gelatinous envelope. Chloroplast a stellate mass with several ridges or rays flattened against the cell wall. Cells 36-43, in diam- eter; 8-celled colony 93, in diameter. Euplankter; tychoplankter among dense growths of miscellaneous algae in shallow, soft water lakes and ponds. Mich., Wis. [ 86 ] FAMILY TETRASPORACEAE In this family colonies of spherical cells bearing long, fine hair-like pseudocilia are embedded in copious mucilage. The pseudocilia are extensions from the protoplast; because they are extremely fine, fav- orable optical conditions or special staining may be required in order to distinguish them. The cell contents are as described for the order, the chloroplast being a parietal cup or plate covering most of the cell wall. The cells usually remain in groups of 4 after division of the parent cell and in most forms are disposed at the periphery of the colonial mucilage. The colony may be amorphous or somewhat definite in shape. Key to the Genera 1. Plant mass mucilaginous, amorphous or intestiniform, macroscopic.____ @ 1, Plant mass' of definite shape, microscopic 3 2. Plant an amorphous, usually floating, mass of mucilage in which fragments of old cell walls remain...» Schizochlamys 2. Plant an elongate, tubular, or intestiniform, gelatinous thallus, with cells arranged at the periphery of the mucilage; fragments of old cell walls lacking — Tetraspora (in part) 5. An attached pyriform gelatinous thallus... Apiocystis 3. A free-floating, globular thallus of few cells, embedded in homogeneous gelatin Tetraspora (in part) TETRASPORA Link 1809, p. 9 Thallus a gelatinous sac, or a tubular or membranous mass, con- taining spherical cells arranged in 2’s and 4’s. Chloroplast parietal, bell-shaped, covering almost the entire wall, with 1 pyrenoid. Cells often showing long, extremely fine pseudocilia which extend far beyond the limits of the colonial mucilage; thallus attached, at least when young, forming bulbous or vermiform masses, later becoming free-floating green skeins or sheets; rarely globular and euplanktonic. Some species of Tetraspora occur in early spring and are among the first plants to develop in ditches and streams of cold water after the melting of ice. They may continue on in favorable habitats throughout early summer. Draparnaldia spp. are commonly found associated with Tetraspora. Key to the Species 1. Thallus cylindrical at all ages, attached; narrowed and coustricted’ below to fommia short stipe 2. 6 2 T. cylindrica 1. Thallus not cylindrical at all ages, becoming bullate or expanded _____ 2 2. Cells with individual, thick gelatinous sheaths... T. lamellosa 2. Cells without individual sheaths, or with sheaths thin and diffluent_____ 8 3. Thallus an attached gelatinous sac, becoming bullate and lobed _ T. gelatinosa 8. Thallus not an attached, bullate, or lobed sac... 4 [ 87 ] 4, Thallus euplanktonic (or incidentally tychoplanktonic) spherical or elongate, composed of relatively few cells evenly distributed or arranged in groups of 4 within the colonial mucilage === T. lacustris 4. Thallus not planktonic, although frequently becoming free-floating in age; at first tubular and sac-like, later expanded and laciniate, forming Ss keinse: 2s cain a mae ath) Se ae eee eee ne es T. lubrica Tetraspora cylindrica (Wahl.) C. A. Agardh 1824, p. 188 Pl. 5, Figs. 1, 2 Thallus an attached, irregularly lobed cylinder of firm mucilage which may be 1 meter long, narrowed at the point of anchorage. Cells scattered, showing arrangement in 4’s only when young, 14-17, in diameter. Forming long, green, intestiniform strands in streams of cold water. Mich., Wis. Tetraspora gelatinosa (Vauch.) Desvaux 1818, p. 18 Pl. 5, Figs. 3, 4 Thallus at first an attached cylindrical sac, later becoming bullate and lobed but not perforate. Cells irregularly arranged in old plants and differing in size, 2.5-13, in diameter. The globular and bullate form of the thallus, even when old, is the chief differentiating character of this species. It is impossible to separate this species clearly from young plants of T. lubrica. In the quiet backwaters of lakes, among rushes. Mich., Wis. Tetraspora lacustris Lemmermann 1898d, p. 152 Plo, Fig. 1 Thallus a free-floating, spherical, or elongate and irregularly shaped, microscopic gelatinous colony containing relatively few spherical cells, the long pseudocilia usually clearly evident. Cells arranged in groups of 2 or 4; 7-10, in diameter. This species is microscopic and apparently free-floating at all stages. It should be compared with Sphaerocystis Schroeteri, from which it may be differentiated by applying some simple stain to determine the presence of pseudocilia. See Smith (1933, p. 352). Common in the plankton of several lakes and inlets. Wis. Tetraspora lamellosa Prescott 1944, p. 348 PI. 5, Fig. 6 Thallus irregularly lobed and saccate, free-floating. Cells spherical, in 2’s, with thick walls and gelatinous, lamellate sheaths which are [ 88 ] distinct and not confluent with the colonial mucilage. Pseudocilia very fine and 20-30 times the diameter of the cell in length. Chloro- last a dense parietal plate covering almost the entire wall. Cells 9-10.5p in diameter. This species differs from others by the possession of distinct lamel- late cell sheaths and the extraordinarily long pseudocilia. Euplanktonic. Wis. Tetraspora lubrica (Roth) C. A. Agardh 1824, p. 188 Pl. 5, Fig. 9 Thallus at first tubular or sac-like and attached, later becoming laciniate, irregularly expanded and floating, or forming streaming gelatinous strands or skeins when in flowing water. Cells in 4's or, when old, irregularly scattered through the rather firm mucilage; 7-10. in diameter. In ditches, in cold springs, and flowing water; and in the marginal flora of lakes. Mich., Wis. APIOCYSTIS Naegeli in Kuetzing 1849, p. 208 Thallus a pyriform or irregularly bulbous, gelatinous vesicle, at- tached by a narrowed base to submerged aquatic plants and fila- mentous algae. Cells spherical, 64 to hundreds, evenly scattered or sometimes in pairs or in circular zonations within the colonial mu- cilage. Cells bearing a pair of very long pseudocilia. Chloroplast parietal, covering most of the wall; with 1 pyrenoid. Underdeveloped stages of this plant can scarcely be differentiated from young or small colonies of Tetraspora. Apiocystis Brauniana Naegeli 1849, p. 67 Plo; Figs. 7,'6, 10 Thallus an attached, pear-shaped, gelatinous vesicle in which the cells are arranged at the periphery in 2’s or 4's. Pseudocilia clearly evident. Cells 6-8u in diameter. Considerable variation in the shape of the vesicle occurs, young colcaie.. being almost round, with a very short stipe, whereas old thalli are oboviform or pyriform. This plant is attached to filamentous algae and submerged aqua- tics such as Utricularia. It is common in acid water habitats where temperatures are fairly high and where there is a great deal of organic material. Mich., Wis. [ 89 } SCHIZOCHLAMYS Braun in Kuetzing 1849, p. 891 Thallus an amorphous gelatinous mass, either soft or firm, con- taining numerous spherical cells irregularly arranged; fragments of cell walls of previous generations lying about clusters of 2-4 cells. Chloroplast usually a single parietal cup, sometimes occurring as 2 parietal plates; in some plants more massive and completely filling the cell; with 1 pyrenoid. Pseudocilia sometimes discernible. Cells divide by a splitting of the mother cell wall into 2 or 4 fragments (sometimes old cell walls appearing as single pieces only), which persist within the colonial mucilage. Key to the Species Gelatinous investment firm; colony of definite shape; Gld mother cell wall-iragments Vor 2) S. compacta Gelatinous investment soft and amorphous; wallifragments of old mother cell’ 2ton 4 = 2 ee S. gelatinosa Schizochlamys compacta Prescott 1944, p. 348 Pl. 4, Figs. 12-14 Thallus microscopic, the mucilage firm and homogeneous and bounded by a definite tegument. Cells globose, with a conspicuous gelatinous cap-like concretion at one side. After division, 1 fragment (rarely 2) of the mother cell wall remains, the mucilage cap per- sisting on the old wall; daughter cells with apposed caps of muci- lage. Cells 7.4-11 » in diameter. This plant should be compared with S. delicatula West, which forms but a single fragment of the mother cell wall upon division to liberate daughter cells. S. compacta differs in the definiteness of the shape of the colonial mucilage, in the larger size of the cells, and in the mucilage cap on the cell wall, the presence of which seems to be a constant character. Rare; in a small pool within a Sphagnum bog. Wis. Schizochlamys gelatinosa A. Braun in Kuetzing 1849, p. 891 Pl. 4, Fig. 15 Plant mass extensive, often macroscopic and free-floating; muci- lage soft and amorphous. Cells spherical, 10-15p in diameter, divid- ing by a splitting of the cell wall into 2 or 4 portions, these persisting and partially inclosing the daughter cells in pairs or in 4’5. Cells have 1 or 2 chloroplasts; pseudocilia often evident. Generally distributed in several types of lakes, but usually in shallow warm water. Mich., Wis. [ 90 ] FAMILY CHLORANGIACEAE Plants in this family are globose, ellipsoid, or oblong, attached by a stipe to other algae or to microfauna. They may be solitary or colonial, arranged in such a way as to form false filaments (i.e., series ) that may be simple or arbuscular. The cells are attached, the anterior end downward, by a stalk-like extension of the sheath, in which the protoplasts are inclosed. There is 1 cup-shaped chloro- plast or 2 elongate parietal bodies, sometimes with a pyrenoid. Usually there is an anterior pigment-spot. Key to the Genera Cells globose or ovoid; epiphytic in the Ege of colonial blue-green algae —....... Stylosphaeridium Cells elongate-ellipsoid or oblong- shite epizoic on micrOratna \=s) 0 Cee ee et Chlorangium CHLORANGIUM Stein 1878, Pl. 19, Figs. 1-7 Cells ellipsoid or spindle-shaped, solitary or in arbuscular series, attached, anterior end downward, by mucilaginous (simple or branched) stalks. Chloroplasts 2 laminate parietal plates; without pyrenoids (?). Cells with 2 contractile vacuoles and a red pigment- spot at the anterior end. Reproduction by longitudinal cell division to form 2 or 4 daughter cells, which escape by the bursting of the mother cell membrane that elongates and forms branching stalks which result in arbuscular colonies. Biflagellate swarmers produced by resumption of motility of vegetative cells. Gametes have been reported. Chlorangium stentorinum (Ehrenb.) Stein 1878, Pl. 19, Figs. 1-7 Pl. 46, Figs. 1, 2 Characteristics as described for the genus. Cells 12-14y in diam- eter, 23-43 » long. Widely distributed in the region, on microfauna in several types of lakes. This species is not so common as Colacium spp. which also attach themselves to Cladocera and copepods. Mich., Wis. STYLOSPHAERIDIUM Geitler & Gimesi in Geitler 1925, p. 608 Cells globose or ovoid, solitary, attached by a slender stipe in the mucilage of Coelosphaerium and Anabaena, and probably to other Cyanophyta. Chloroplast solitary, massive, covering the posterior (outer) portion of the cell wall, and containing a single pyrenoid. This genus should be compared with Peroniella, a member of the [ 91 ] Chrysophyta which lacks a pyrenoid and has a parietal, plate-like chloroplast along the lateral walls. There are species in that genus which are similar in shape and habit to Stylosphaeridium, but they are usually much larger. Stylosphaeridium stipitatum (Bachm. ) Geitler & Gimesi in Geitler 1925, p. 608 Pl. 4, Figs. 7-9 Characteristics as described for the genus. Cells 5-8» in diameter, 8-10 long; stipe 20p long. This species apparently is not widely distributed in lakes of our region, but in the habitats where it does occur it is common. The plants are gregarious, and the host colony is usually thickly beset with the epiphytes. Mich., Wis. FAMILY COCCOMYXACEAE Plants in this family are ovate, ellipsoidal, cylindrical or fusiform cells, either solitary or forming colonies inclosed by a copious muci- laginous investment. There is a single parietal chloroplast which may have a pyrenoid. The genera of the Coccomyxaceae are not altogether typical of the Tetrasporales but are precluded from possible classification with the Chlorococcales by the fact that the cells can undergo cell division in the vegetative state. Key to the Genera? Cells fusiform or elongate-cylindric, arranged in a copious mucilage to form spindle-shaped colonies —___--------------- Elakatothrix Cells ovate or oblong, arranged in a flat plate withinea, rectangular gelatmous sheath 2 Dispora DISPORA Printz 1914, p. 32 Cells ovate to oblong, sometimes nearly spherical; pairs or quar- tets of cells irregularly arranged within a wide gelatinous sheath, forming a flat, rectangular plate, the colony increasing in size by cell division in 2 directions in the same plane; chloroplast a parietal cup, without a pyrenoid (?). Dispora has been placed by Printz in another family, the Pleuro- coccaceae, together with Coccomyxa, Pseudotetraspora, and Elakato- thrix. Fritsch (1935) suggests that a suitable place for Dispora would be with the Palmellaceae. 2Since this key was written, Coccomyxa dispar Schmidle has been collected in a Michigan lake. This consists of ellipsoidal cells embedded in amorhous mucilz ve. [ 92 ] Dispora crucigenioides Printz 1914, p. 32 Pl. 46, Figs. 5, 6 Characteristics as described for the genus; cells broadly ovate to nearly spheroidal, 3-5y in diameter, 4—6y long; colonies 20-30, in width. Tychoplankter; in soft water, northern lakes. Mich. ELAKATOTHRIX Wille 1898, p. 302 Gelatinous, fusiform or irregularly shaped colonies containing fusi- form or ovate cells. Free-floating at least when mature. Cells with either 1 or both poles acutely pointed. Chloroplast a parietal plate containing 1 or 2 pyrenoids and covering almost all the wall along one side. Division transverse, the daughter cells lying in pairs with their longitudinal axes parallel with the axis of the colony. Key to the Species Cells small, narrow, spindle-shaped, 3—6y in diameter, pole: pomted, the other rounded =. E. gelatinosa Cells broadly fusiform, larger, up to 15 in diameter, taperinestoa-point: at beth poles=.-- 1) 82 eS E. viridis Elakatothrix gelatinosa Wille 1898, p. 802 Pl. 3, Figs. 18, 14 A free-floating colony of 4-16 fusiform cells with longitudinal axes parallel, arranged end to end in pairs, broad at the adjoined poles, tapering to a blunt point at the opposite pole. Cells 3-6, in diam- eter, 15-25, long; colony 10-30» in diameter, up to 160, long. Rare to common in various types of lakes; mostly euplanktonic. Mich., Wis. Elakatothrix viridis (Snow) Printz 1914, p. 31 Pl. 4, Figs. 1, 2 A broadly ellipsoid colony, attached at first but later becoming free-floating. Cells ovate or fusiform and arranged in pairs; dividing transversely, but daughter cells with longitudinal axes at oblique angles to one another. Cells 6-15, in diameter, 35, long. Rare. Mich., Wis. ORDER ULOTRICHALES As interpreted here, this order includes unbranched, simple fila- ments of mostly uniseriate cells, multiseriate in one suborder. With few exceptions, the cells are cylindrical and contain a single, band- [ 93 ] like chloroplast which shows significant similarity to that possessed by the Volvocales and most Tetrasporales. Usually 1 or more pyre- noids are present. In some forms there is a basal-distal differentia- tion, with an attaching holdfast cell. Most species which are attached when young, however, become free-floating. Isogametes and zoo- spores are produced in unspecialized vegetative cells. There are two suborders. SUBORDER ULOTRICHINEAE FAMILY ULOTRICHACEAE Nearly all the members of this family have cylindrical, uniseriately arranged cells, either adjoined or separated from one another. In a few forms there is a gelatinous sheath. The chloroplast is a parietal late or band which varies in the degree to which it encircles the cell wall. In a few species a special holdfast cell develops at the base of the filament, the only cell incapable of further division. Re- production is by vegetative proliferation, by palmella stages, by zoospores, and by isogametes. Key to the Genera 1. Filaments tapering at one end, and ending in a stout blunt point __Uronema 1. Filaments not tapering, the same diameter throughout > 2 2. Filaments inclosed by a gelatinous sheath ____- Fan aR Sag Ses 2 es 3 2. Filaments not inclosed by a gelatinous sheath ________________________.. f 3. Cells cylindrical, adjoined at the end walls to form continuous filaments. 4 3. Cells oblong or spheroidal, sometimes not forming continuous threads 5 4. Chloroplast a parietal band, nearly encircling the cell- Ulothrix (in part) 4, Chloroplast a parietal fold or plate, not encircling the cell, covering only a small portion of the wall _________ Geminella (in part) 5. Cells spheroidal, adjoined in some species with the wall composed of 2 helmet-shaped halves which adjoin in the miGrePiOM = ee DS 2 ee re ar goa A Radiofilum 5. Cells of different shapes from those above; wall motcomposediotstwovhalves = esse eee ee eee § 6. Cells cylindrical, frequently in linear pairs, forming filaments ofsndefinite: lenothylc:. 2.2 2bis e300. es Geminella (in part) 6. Cells transversely elliptic, in discontinuous series, often in groups of 4, each group inclosed by a sheath; filaments short —._________. Hormidiopsis 7. Filaments with cells in pairs, the protoplasts at some distance from the wall, the intervening space filled with lamellate (¢elatmous| deposits Binuclearia 7. Filaments with cells not in pairs and without gelatinous Gepasits aboubthe protoplasts eee a eee ee 8 8. Filaments of indefinite length, composed of many cells, SOMMELIMEST With basallcitterem tl ctic imams meee eae nee enna nn enn n nS uOnESE EEE 9 [ 94 ] 8. Filaments of definite length, short and frequently interrupted; basalyditierentiation lacking - Sess ee ees Stichococcus (in part) 9. Filaments often showing basal differentiation; chloroplast a complete or-nearlycomplete parietal band = se Ulothrix (in part) 9. Filaments without basal differentiation; chloroplast a folded plate along one side of the cell and not nearly encircling it 10 10. Chloroplast as long as the cell or nearly so (See Ulothrix cylindricum, however)... Stichococcus (in part) 10. Chloroplast half the length of the cell = Hormidium ULOTHRIX Kuetzing 1833, p. 517 Simple, unbranched filaments of cylindrical cells, often showing basal differentiation and arising from a special holdfast cell; becom- ing free-floating in some species. Chloroplast a parietal band which extends %% to 34 of the way around the cell (forming a complete ring in 1 species), and sometimes extending the entire length of the cell. Asexual reproduction by 4-8 quadriflagellate zoospores cut out from the protoplast of unspecialized cells; sexual reproduction by iso- gametes formed 8-16-64 in a cell, smaller than the zoospores and biflagellate. Palmella stages not uncommon. This genus is distinguished from others in the family principally by the approximate completeness with which the chloroplast covers the wall, and also by the attached habit of growth, which involves a basal holdfast cell in some species. Key to the Species 1. Filaments (20)—25-45—(60) in diameter; wall thick; chloroplast a ‘complete parietal band. U. zonata 1: “Filaments 20 or less in diameter; ‘wall thin: 2-2. 9 2. Filaments 11—20u in diameter CUE never Ree Rai Ae Wake eee ene 3 2°) alaments ‘smaller. 5—1 Uz in) diameters. eee x 3. Filaments composed of long, cylindrical cells, 11-12.5,» in diameter, the length 2'4-3 times the width _______________. U. cylindricum 3. Filaments composed of shorter cells, 13-20u in diameter _- 4 4. Cells up to 20u in diameter, shorter than wide U. tenuissima 4. Cells 13-16y in diameter, 1-2 times longer than wide —.... U. aequalis 5. Cells 4—5u in diameter; chloroplast extending nearly the entire lemme orsthie cell ¢2utes cee pee eee le The ho WO U. subtilissima 5. Cells wider; chloroplast extending 33 or less the length of the cell 6 6. Cells 5-6u in diameter, short-cylindric; chloroplast covering aor less .Olgthe;cellawall ss ee 2 ae ee U. variabilis 6. Cells larger, 6-94 in diameter _...... _. gk SP RR oe Nee ier DB ah 2c w 7. Filaments constricted at the cross walls, 5.7—9u in diameter; cells 2—4 times. ~diams long) Shs Oo hee oessccccctesesesee U. subconstricta 7. Filaments not or slightly constricted at the cross walls; cells rectangular, 7.5—10y in diameter, the length 2/3 to 11/3 (HOG: AGG (a oats arc bnes tr ki ica A een he eee ed OLS ten U. tenerrima Ulothrix aequalis Kuetzing 1845, p. 197 Pl. 6, Fig. 1 Filaments very long, composed of cylindrical cells and without constrictions at the cross walls. Chloroplasts a parietal plate extend- ing 4 of the distance around the wall. Cells 13-15.54 in diameter, 18-30 long. Common; forming pure, bright green masses in shallow water of several lakes and swamps; scattered among other algae. Mich., Wis. Ulothrix cylindricum Prescott 1944, p. 349 Pl. 6, Fig. 2 Filaments long, curved, and lightly entangled. Cells elongate- cylindric, 11-12.5. in diameter, 214 to 3 times longer than wide; the wall thin and not constricted at the joints. Chloroplast a broad band, nearly equal to the cell in length and folded around % of the cir- cumference; pyrenoids 2-5. This species should be compared with Ulothrix aequalis Kuetzing, which has thick walls, shorter cells, fewer pyrenoids, and a different form of chloroplast. Tychoplankter. Wis. Ulothrix subconstricta G. S. West 1915, p. 82 Pl6; Figs 1 Filaments planktonic, composed of slightly inflated cells, which are moderately constricted at the cross walls and sometimes inclosed in a gelatinous sheath. Chloroplast a parietal plate extending through about 3 of the median region of the cell, sometimes with a pyrenoid. Cells 5.7-9 in diameter, 10-36, long. Euplankter. Wis. Ulothrix subtilissima Rabenhorst 1868, Alg. Exsic. No. 655 Pl. 6, Fig. 3° Filaments long and slender, free-floating or attached. Cells very slightly inflated and constricted at the cross walls. Chloroplast ex- tending the entire length of the cell, with 1 pyrenoid. Cells 4-5, in diameter, 11-14.8, long. In shallow water of a swamp. Wis. Ulothrix tenerrima Kuetzing 1843, p. 253 Pl. 6, Fig. 12 Filaments free-floating or attached; long, or in short sections; com- posed of cylindrical, relatively short cells with constrictions at the [ 96 ] cross walls. Chloroplast an irregularly folded plate, about 1%4 the length of the cell, with 1 pyrenoid. Cells 7.5-10» in diameter, 10-15. long. Common in many lakes and ponds, both the eutrophic and the soft water types. Mich., Wis. Ulothrix tenuissima Kuetzing 1833, p. 518 P61, Wigs, 11912 Filaments long, composed of cylindrical cells that are shorter than wide, 16-20 in diameter, thin-walled and not constricted at the cross walls. Chloroplast a broad band encircling about 24 of the circumference of the cell, with 2 or several pyrenoids. Mich. Ulothrix variabilis Kuetzing 1849, p. 346 Pl. 6, Fig. 18 Filaments long, slender, and entangled, forming cottony masses. Cells cylindrical, without constrictions at the cross walls. Chloro- plast a folded, parietal plate, 14 to 24 the length of the cell, with 1 pyrenoid (or 2 ?). Cells 4.5-6 in diameter and up to 15, long. Common in a variety of lakes and in seeps along sandy shores; often forming bright green, slimy masses in trickles from springs. Mich., Wis. Ulothrix zonata (Weber & Mohr) Kuetzing 1833, p. 517 Pl. 6, Fig. 14 Filaments attached, usually long and stout, variable in diameter in the same plant mass. Cells short , or elongate-cylindric, sometimes slightly swollen, with constrictions at the cross walls. Cell walls thick, especially near the base of the filament. Chloroplast a com- lete circular band in the midregion of the cell, with several pyre- noids. Cells 20-45, in diameter, 21-60, long. Not uncommon in several lakes in early summer; frequently found in cold streams, artificial ponds, and in drinking troughs in which there is running water, especially in spring. Mich., Wis. HORMIDIUM Kuetzing 1843, p. 244; emend. Klebs 1896, p. 326 Simple filaments of cylindrical, undifferentiated cells. Chloroplast a parietal plate extending around the cell for 14 or less of the cir- cumference; 1 elongated or oval pyrenoid. Filament readily frag- menting to form Stichococcus-like sections. [ 97 ] Hormidium Klebsii G. M. Smith 1933, p. 385 Pl. 6, Fig. 4 Long unbranched filaments in which there is no basal-distal dif- ferentiation. Cells cylindrical, not constricted at the cross walls. Chloroplast a parietal plate covering only a small portion of the cell wall. Cells 5.8-6 in diameter, 15.6-25, long. In Sphagnum bogs and roadside ditches. Wis. URONEMA Lagerheim 1887, p. 517 Simple, unbranched filaments which are always attached. Cells cylindrical, the basal cell forming an organ of attachment, the ter- minal cell tapering unsymmetrically to a blunt boint. Chloroplast a parietal plate, 14 to 24 the length of the cell; with 1 or 2 pyrenoids. Uronema elongatum Hodgetts 1918, p. 160 Pl. 5, Fig. 5 Cells cylindrical, as much as 13 times their diameter in length, and 5-10u wide. Chloroplast a parietal folded plate extending for 24 of the circumference and 14 to 24 the length of the cell; with 2 pyrenoids. Terminal cell unsymmetrically tapering to a blunt point and often slightly curved. This plant should be compared with germlings and young stages in the development of Ulothrix and such members of the Chaeto- phoraceae as Stigeoclonium and Chaetophora. The separation of Uronema from Ulothrix has been questioned; but the tapering apical cell persisting through maturity, the permanent attachment of the plants, and the type of basal holdfast of Uronema seem to be suffhi- cient justification for the retention of the two names. Attached to filamentous algae and other submerged aquatics in shallow backwaters. Mich., Wis. STICHOCOCCUS Naegeli 1849, p. 77 Simple unbranched filaments of short, cylindrical, undifferentiated cells, which are often loosely connected, so that interrupted series are formed. Chloroplast a parietal folded plate, covering 1 or less of the cell wall, with 1 pyrenoid. Filament fragmenting easily to form short sections or solitary cells, which by vegetative division rebuild longer, curved (sometimes coiled) or straight filaments. Fre- quenting moist substrates in association with Protococcus [Pleuro- coccus]; also in algal mixtures encrusting submerged wood, or on aquatic plants. [ 98 ] Key to the Species Da @ellse 24 te Water. * 2-0 * re weeds eee ements |e hi Se! PI en 2 lee Celisto—Gue wide tte 2k eee ee eee) | TL eStonibhilis 2: \Gells 2—3.on awide; 3-S4 long: se ee ek et S. bacillaris 27) Gellsio—4 wide’ and ‘upto SOn lompn = 2 TS, scopulinus Stichococcus bacillaris Naegeli 1849, p. 77 Pl. 6, Fig. 5 Filaments composed of short cylindrical cells very slightly con- stricted, if at all, at the cross walls. Chloroplast a pale green parietal plate or folded disc covering a small portion of the wall. Cells 2-3.5u4 in diameter, 3-8, long. On moist, aerial substrates, associated with other algae to form films on floating wood, etc. Mich., Wis. Stichococcus scopulinus Hazen 1902, p. 161 Pl. 6, Fig. 6 Filaments of relatively long cylindrical cells without constrictions at the cross walls. Chloroplast a long, folded plate with an indistinct pyrenoid. Cells 3-4 in diameter and up to 30, long. Our specimens are questionably assigned to this species. Hazen (I.c.) described the species as growing in dark green skeins on dripping rocks. It has not been possible to differentiate it clearly from S. bacillaris forma confervoidea Hazen (l.c., p. 60), except that the cells in S. scopulinus average slightly wider. On stones and moist soil, forming small green patches. Mich., Wis. Stichococcus subtilis (Kuetz.) Klercker 1896, p. 103 Pl. 6, Figs. 7, 8 Filaments very long, composed of rather stout, cylindrical cells without constrictions at the cross walls. Chloroplast an elliptical parietal plate with 1 pyrenoid. Cells 5-7-(8), in diameter, 7-20, long. In shallow water of beach pools and lake margins. Mich., Wis. GEMINELLA Turpin 1828, p. 329 Filaments unbranched and uniseriate, composed of spheroidal, broadly ovoid, or short cylindrical cells inclosed by a wide gelat- inous sheath and usually separated from each other; daughter cells approximated for some time after division to give a paired arrange- ment. Chloroplast a parietal folded plate, with 1 pyrenoid. [ 99 ] Key to the Species 1. Cells oblong or subquadrate; the lateral walls unsymmetrical because of longitudinalifolds == = a G. crenulatocollis 1. Cells ovate, spheroidal, or oblong to subcylindrical; wall without folds, the cells symmetrical. ss ee 2 2. Cells adjoined to form continuous filaments______________________ G. minor 2. Cells not adjoined, separated from one another within a\gelatinous sheath... 2. 2h 2S ee 3 3. Cells in linear pairs, pairs separated from neighboring pairs bya) cells length; cell 5—8,in*diameter> = See G. interrupta 85 (Gells\motiin pairs; evenly spaced! ina. linear Series22 8 4 4, Cells séparated from one another by a cell’s length or more G. ordinata 4, Cells separated from one another by less than a cell’s length G. mutabilis Geminella crenulatocollis Prescott 1944, p. 349 Pl. 6, Figs. 9, 10 Uniseriate filaments of irregularly ovoid, subquadrate, or oblong cells, with emarginate, crenulate, or wavy lateral walls; truncate or broadly rounded at the poles, with folds and ridges sometimes pres- ent in the lateral walls. Cells inclosed by a broad gelatinous sheath and arranged in linear pairs, but often evenly spaced. Chloroplast an irregularly shaped, folded parietal plate, which makes an almost complete cylinder within the wall, often showing a ridge or wing- like flange extending radially toward the wall. Cells 12-15p in diameter, 18-24 iong. This species should be compared with G. mutabilis, from which it differs in the irregularly creased cell wall and the shape of the chloroplast. Originally described from Wisconsin, this species has since been found in Michigan. In soft water and acid swamps; tychoplanktonic in mixtures of algae in lake margins; in Sphagnum bogs. Mich., Wis. Geminella interrupta (Turp.) Lagerheim 1883, p. 68 Pl. 6, Fig. 15 Uniseriate filaments of broadly ovoid or subcylindric cells; pairs o1 cells separated from the next pair in the series by at least a cell’s length. Cells 5-84 in diameter, 6-15, long. Chloroplast a parietal plate covering %% of the cell wall. This species, even more than others in the genus, seems to be confined to soft water lakes. It appears in great profusion in desmid habitats. Mich., Wis. Geminella minor (Naeg.) Heering 1914, p. 41 Pl 5 Mig. Ad, Uniseriate filaments of short, cylindrical cells adjoined without interruption within a wide gelatinous, homogeneous sheath. Chloro- [ 100 ] plast covering the entire lateral walls, but narrow, ring-like, and zonate immediately following cell division. Cells 4-8 in diameter; filament (including sheath) 8-18, in diameter. This species often appears in the tychoplankton of acid lakes and in small pools of Sphagnum bogs. Mich., Wis. Geminella mutabilis (de Bréb.) Wille 1911, p. 72 Pl. 6, Fig. 16 Uniseriate filaments of broadly ovate, spheroidal, or cylindrical cells, almost equally separated from one another, but with daughter cells remaining in approximation. Chloroplast completely covering the cell wall. Cells 9-13-( 20), in diameter. Intermingled with other algae in shallow water of small lakes and swamps. Wis. Geminella ordinata (West & West) Heering 1914, p. 41 Pl. 24, F ig. 9 Uniseriate filaments of oblong-ellipsoid cells, arranged in an inter- rupted series, separated from each other by a distance of a cell’s length or more. Chloroplast solitary, extending completely around the wall. Cells 5-5.8, in diameter. Intermingled with other algae in shallow water of lakes and ponds. Wis. HORMIDIOPSIS Heering 1914, p. 50 Filaments short, composed of from 5 to 20 cells, arranged in con- tinuous or interrupted linear series. Cells ovoid, cylindric, or trans- versely ellipsoid, inclosed by a gelatinous sheath. Chloroplast a parietal, incomplete band, without a pyrenoid (or with 1 ?). Oil formed as a food reserve. Reproduction by zoospores or gametes unknown. Hormidiopsis ellipsoideum Prescott 1944, p. 350 Pl. 7, Figs. 1, 2 Cells transversely elliptic, arranged in linear series in groups of 4, each group inclosed by a wide, hyaline, and homogeneous gelatinous sheath. Chloroplast a parietal band as wide as the cell but not en- tirely encircling the wall; with 1 pyrenoid. Cells 8» in diameter, 5.5p long; filament 14.8» wide. Although this plant was found in only one collection it appeared distinctive enough to be worthy of description. Hormidiopsis is a little-understood genus, apparently containing but one other species, H. crenulata Heering. To this genus, Heering has also assigned ques- [ 101 ] tionably a plant previously described by Borge as Ulothrix monili- formis. Although our plant has the cell shape of the latter species and is approximately the same size, it differs in the arrangement of the cells. Ulothrix moniliformis Borge possesses cells in continuous filamentous arrangement inclosed by a sheath. All of the Wisconsin specimens had the cells arranged in crooked filaments in linear groups of 4, each group with an individual sheath. Occasionally the cells showed a tendency toward an irregular bilateral arrangement. The chief objection to placing the Wisconsin species in Hormidiopsis is the presence of a pyrenoid. The cell shape and arrangement would seem to preclude the assignment of this species to Geminella. Addi- tional observations and life history studies are necessary before the plant can be satisfactorily identified. Found in a Sphagnum bog lake intermingled with other algae. Wis. BINUCLEARIA Wittrock 1886, p. 9 Filaments of long cylindrical cells. Protoplasts short-cylindric or oblong with rounded apices; not filling the cell, but surrounded by lamellated mucilage, which fills the space between the protoplasts and the end walls. Protoplasts in pairs (as a result of their remaining close together after cell division) separated by a thin cross wall. Chloroplast laminate, forming a band in the midregion of the cell; without pyrenoid. Binuclearia tatrana Wittrock 1886, p. 9 Pl. 7, Figs. 7-9 Cells 7-10, in diameter; the length sometimes as much as 6 times the width. Common in acid bogs and soft water lakes; appearing quite fre- quently in small pools and ditches where the water is shallow and where there is an abundance of organic matter. Mich., Wis. RADIOFILUM Schmidle 1894, p. 47 Filaments either unbranched or branched, the branches sometimes anastomosing to form a series of links. Cells lenticular, spherical, or oblate-spheroidal, dividing in 1 or 2 planes. The cell wall (at least in some species) composed of 2 cups or helmet-shaped halves, which adjoin in the midregion to form a transverse rim around the cell, at which point cell division occurs, new cell halves being interpolated between the older parts of the cell wall. Chloroplast a parietal plate, [ 102 ] _ —OrrtC rh with 1 pyrenoid, lying along the transverse wall. Filament inclosed by a broad gelatinous sheath through which fibrillar concretions radiate to the periphery. Key to the Species 1. Cells transversely ellipsoid or subquadrate, arranged to form a long continuous filament, inclosed in a relatively narrow sheath; cell wall halves not apparent —_____________-_--________. R., flavescens 1. Cells a different shape from above, not forming a continuous simple filament —- sete heh tS 5 5 eee. Say cena Ohl CS ee 2 2. Cells transversely lenticular, pointed at the poles, separated from each other in a wide, gelatinous sheath, sometimes irregularly arranged, forming filaments with anastomosing branches; cellswallehalves;mot apparent 2. 25s ee R. irregulare 2. Cells spheroidal, evenly spaced and separate from each other; cell wall halves evident, forming a transverse rim around 1d c=). (675) | | ee ae Ose ee 28 ae ee ene eee See ee ree Sete R. conjunctivum Radiofilum conjunctivum Schmidle 1894, p. 48 [R. apiculatum West & West] Pl. 7, Fig. 6 Filaments short, fragmenting readily, composed of spheroidal cells in a wide gelatinous sheath. Cell walls formed by 2 cup-shaped halves adjoined in the midregion and forming a rim which produces an apiculation at each side of the cell. Chloroplast a parietal plate lying along the end wall. Cells 6» in diameter, 4—6y long. Very common in a large number of lakes and swamps, especially in soft water and acid habitats, hence often associated with desmids. Mich., Wis. Radiofilum flavescens G. S. West 1899, p. 57 Pl. 7, Fig. 10 Filaments long, composed of transversely ellipsoidal or subquad- rate cells in a narrow gelatinous sheath in which radiating fibrils are apparent. Chloroplast a parietal plate. Cells 6.8-15, in diam- eter, 5-10, long; filament 9-25, wide, including sheath. Some specimens in our collections are larger than the dimensions usually reported for R. flavescens, and have cells that are often def- initely subquadrate. It is possible that such an expression justifies a separation to form a new species. The shape of the cell in this species is known to vary, however. Scarce; in a few soft water lakes and in Sphagnum bogs. Mich., Wis. [ 103 ] Radiofilum irregulare (Wille) Brunnthaler 1918, p. 7 Pl. 7, Figs. 3-5 Filaments long, irregularly branched, branches often anastomosing to form a series of chain-like links. Cells transversely ellipsoid, divid- ing in 2 planes and appearing in more than | series within the wide gelatinous sheath. Cell wall in 2 saucer-shaped halves, adjoined in the midregion, the line of juncture not always evident. Cells 7-10 in diameter, 3.5-5, long. Very common in desmid habitats and soft water lakes. Mich., Wis. Published descriptions of this species do not mention the two-part structure of the cell wall, a character of R. conjunctivum. Also the shape of the cells in our specimens agrees closely with a plant which W. and G. S. West originally described as R. apiculatum. The ar- rangement of the cells and other features, the irregular form of the filament in particular, justify referring our specimens to R. irregulare. Radiofilum apiculatum West & West has been reduced to synonymy with R. conjunctivum. The characteristics of our specimens would apparently justify emending the description of R. irregulare if it were determined that the type specimens possess the wall structure of R. conjunctivum. SUBORDER SCHIZOMERIDINEAE FAMILY SCHIZOMERIDACEAE In this family, which consists of the single genus Schizomeris, the unbranched filamentous habit takes on a multiseriate expression. The plant is uniseriate in the basal portion, where the cells are long and cylindrical, but becomes multiseriate through cell division in 3 planes in the distal region, where the cells are brick-like and quad- rangular. The cross walls of the lower cells are thick plates. Chloro- plasts are broad parietal bands which encircle about %4 of the cell wall in the lower cylindrical cells, but become massive and com- pletely fill the cells in the distal portion of the filament. The multiseriate habit and the method of zoospore escape (men- tioned below) are characters which have influenced some phycol- ogists to treat Schizomeris as a member of the Ulvaceae. It is an enigmatic plant, and its inclusion with either the Ulotrichales or the Ulvales seems justifiable. SCHIZOMERIS Kuetzing 1848, p. 247 Characters as described for the family. Filaments uniseriate below, with cylindrical cells; multiseriate above, with brick-like cells. Chloroplast a parietal plate nearly encircling the lower cells, with [ 104 } several pyrenoids; distal cells have a dense chloroplast of indefinite shape. See Smith (1933, p. 457) for a discussion of the various opinions concerning the taxonomic position of this genus. Schizomeris Leibleinii Kuetzing 1848, p. 247 Pl. 7, Figs. 11-18 Filaments stout, macroscopic, 20-25 in diameter below, and as much as 150, wide in the multiseriate upper portion of the frond. Cells 15-30 in diameter. Zoospores formed in the upper limits and escaping through an opening in the apex of the frond after interior cell walls have disintegrated. Rather rare; in shallow water and marsh-like margins of both hard and soft water lakes; also in several swamps. Mich., Wis. ORDER MICROSPORALES In this order there is only one family, which is monogeneric. The plants are unbranched filaments, which are free-floating except when young. The most distinctive feature is found in the structure of the cell wall. The cells are cylindrical, with walls composed of two H-shaped sections which adjoin in the midregion. In the thin-walled species, however, this feature is scarcely discernible. When the fila- ment dissociates, the cells fall apart into H-shaped sections because the cleavage occurs at the points of juncture in the midregion rather than at the cross walls. The end of a filament shows a half of the H adjoined to the terminating cell. A thin, internal cellulose mem- brane holds the wall sections together. Another characteristic which differentiates this order is the morphology of the chloroplast. Al- though it shows different specific expressions, its general form is that of a parietal reticulum or perforated sheet, which may be dense and padded or open and thin, covering almost all of the cell wall. Often the padded character gives the appearance of there being several chloroplasts. Starch accumulates as a food reserve, but there are no pyrenoids. The absence of pyrenoids and the H-shaped wall sections are characteristics in common with Tribonema in the Chrysophyta. In that genus there are 2 to several disc-like, pale green chloroplasts, and starch is not formed. Asexual reproduction is by biflagellate zoospores; gametes are unknown. Aplanospores are frequently formed, especially when water temperatures become high. [ 105 | Microspora, the only genus, is sometimes included in the order Ulotrichales. The characteristics of Microspora species are so dis- tinctive, however, that placing them in a separate order seems justifiable (Heering, 1914; et al.). FAMILY MICROSPORACEAE MICROSPORA Thuret 1850, p. 221 Plants unbranched, unattached filaments of uniseriately-arranged cylindrical, or slightly swollen, cells (attached filaments are not un- known, however). Cell walls thin in some species; in others thick and lamellate, composed of 2 sections overlapping in the midregion. Filaments fragmenting readily when mature by the separation of the walls at their point of juncture, so that H-shaped sections and frag- ments are formed. Chloroplast either a dense and irregularly padded parietal plate or net, or an open meshwork or “rosenkranz’” form of reticulum; pyrenoids lacking. Cells frequently forming aplanospores or akinetes, the latter globose, with much-thickened walls. Key to the Species 1. Walls thin, lu or léss in thickness; juncture of the wall sections in the midregion of the cell not clearly evident except upon fragmentation OPtheshlament ss) eee ee ee eee 2) 1. Walls 1.5-2.5u thick, often lamellate; juncture of the wall sections clearly evident —_..__------------------------------------------------- 6 2. Chloroplast an open meshwork, stringy, but sometimes thickened in places___——--------------------------=-------- 3 2. Chloroplast a parietal, perforated plate or close meshwork covering most of the cell e171 | Me ce Nee lel sacle x SR lon wh J Dt erty 4 3. Cells distinctly cylindrical, 14-17» in diameter, 22-354 long .. M. floccosa 3. Cells quadrate or short-cylindric, 11—-14y in diameter PTAs Hho} (0) 0272) 1) | (0) 04 eee reer ee reece peepee saa crc eaee een ncaace ccna: M. Willeana 4. Cells about 9u in diameter, 1-3 times the diameter in length; chloroplast a granular plate M. stagnorum 4. Cells narrower, and usually shorter; chloroplast dense —________-- 5 5. Cells 6.7-9.5u in diameter, quadrate (sometimes as much as twice the diameter in length); constricted at the cross walls _ M. tumidula 5. Cells 5.5-7.0u in diameter, shorter than wide, or quadrate; MOM COUStEICLEC mata tine KCLOSS Hive |S eee ee ee M. quadrata 6. ‘Filaments 21.5—407: im diameter 224 ee sat 6. Filaments 20 or less in diameter ..--.....-.---------------------------------------2- 2 8 7, Filaments 21.5-27» in diameter, up to twice the diameter in length; slightly constricted at the cross walls M. amoena 7. Filaments 26—-33y in diameter (rarely more ), cells usually cylindrical, 1-14 times the diameter in length M. crassior 8. Cells cylindrical, 8-12 in diameter, up to twice the diameter in length__._________-____--------------= M. pachyderma 8. Cells quadrate or cylindric, 13-20» in diameter: 325-2 ie ee 9 [ 106 ] 9. Cells elongate-cylindric, 13-15 in diameter, up to 3 times FhegGiamictcrrmplonCth.-. -=>=S CHAETOPHORACEAE FAMILY CHAETOPHORACEAE In this family, as the name implies, most of the genera bear setae or hairs. These may develop as outgrowths of the cell wall or they may be formed by the attenuation of cells toward the apices of the branches, forming short or long hyaline bristles, one or more cells in length. The two chief expressions of these plants are the erect, branched filament, and the prostrate, cushion-like expansion. In some forms the thallus involves both a horizontal and an erect por- tion. In prostrate species the thallus may be a single layer of cells or it may be cushion-like and several cells in depth, especially in the center, becoming 1-celled in thickness at the margin. In such plants the true filamentous character may be lost because of the compact- ness of the cells and the irregular habit of branching. Key to the Genera 1. Plant a prostrate or creeping filament, little or not at all branched_____.. 2 1. Plant a much-branched filament; filaments often adjoined and forming erect tufts, or Pseudoparenchyniatous expansions =. 9-8 ss ee 3 2. Filament creeping, little or not at all branched, if so, with branches not erect —___---__----------------------- Aphanochaete 2. Filaments creeping,.with infrequent, short branches ___________ Chaetonema 3. Plant consisting of an axial row of large, barrel-shaped or cylindrical cells giving rise to nodal whorls of branches, or oppositely arranged fascicles, of much smaller cells; thallus inclosed faba SOLE COPIOUS MANCHA Ge 22 ee Draparnaldia 3. Plants without an axial row of distinctly larger cells; branch cells about the.same size as those of the, main axis 2) Se 4 4, Plant a branched filament, the cells of the branches scarcely smaller than those of the main axis, gradually tapering to long or short setae or to pointed apical cells; horizontal or prostrate portion of the thallus often present; thallus inclosed in a thin mucilage which mipy snipe, be eViGent e252 ot ot ae es Stigeoclonium PEEP TIE DIA LSA ADO VG eee wits NOL 50 ES EN hte pe ko ee ee eelant anerece: branched “filament <2... 26 2 ee el 6 5. Plant a horizontal or pseudoparenchymatous expansion __________----------- 7 6. Plant a much-branched filament inclosed in firm, copious mucilage, forming macroscopic thalli of definite Shapes branches attenuate. 8225! aos the ee Chaetophora 6. Plant microscopic; branches not at all or scarcely attenuate; investing mucilage wanting —_______________-_- Microthamnion [ 113 ] . Plant endophytic in the walls of large algae (sometimes epiphytic also), consisting of an irregularly branched filament or pseudo- parenchymatous mass of cells which bear no setae Entocladia . Plant epiphytic or otherwise attached, not endophytic; pseudoparenchymatous or discoid —. Brh esas . Thallus a compact dise of definite limitation, with colorless hairs arising from the outer sheath of the cells; filaments not evident _. Chaetopeltis . Thallus a flat, broad, epiphytic disc with filaments evident; cells without setae —-.________--. _. DUR! pacer ees Cee ae 9 . Thallus a broad, epiphytic disc, several cells in thickness, with filaments radiating from a common center; margins of the frond definite; evanescent hairs sometimes present__-_-.___________- Pseudulvella . Thallus an irregularly spreading epiphyte; filaments adjoined and compactly arranged, not radiating from a common center; one cell infthickness;!setae lacking: 2 2ss Cee ee See eee Protoderma STIGEOCLONIUM Kuetzing 1848, p. 253 A branched filament arising from a prostrate portion of a thallus, which may be reduced to a pseudoparenchymatous mass of cells. In some species the major portion of the plant spreads in loosely branched, horizontal filaments; plant covered by a thin, scarcely evi- dent, film of mucilage. Branches of first and second order either al- ternate or opposite, and composed of cells scarcely smaller than those of the main axis, ending in bluntly pointed or setiferous cells. Chloroplast a parietal plate covering most of the cell wall, especially in the cells of the branches; 1 to several pyrenoids. See Hazen (1902, Pp: fon) OD Ot Ol He i co 193) on the taxonomy of this genus in the United States. Key to the Species . Plants mostly prostrate and creeping; filaments Wathia) few. Short vertical branches. ee ee S. polymorphum . Plants mostly erect, branched filaments; horizontal portion of the ‘thallus* reduced 223s et ee eee ee 2 » Branching mostly altemate!- 25-3 eee 3 / Branching mostly opposite. = eee i . Walls of main axial cells 1.5-2.5—(4)u thick; branching very irregular, with long and tapering, as well as short, arbuscular or rhizoidal branches produced throughout the length of the main axis__S. pachydermum . Walls of main axial cells thinner; branching regular, the branches gradually attenuated: toward the apices 20. i ee 4 . Plants short-tufted; apices of branches not tapering to setae but 'short-pointed 2.2 eee een ie ee S. nanum . Plants not short-tufted; branches elongate, gradually attenuate, and: endmptnilong. setae. se ee 5 . Plants slender, main axis less than 8u in diameter... S. attenuatum » Plants stouter) main aus 8—ISi) inidiameter 2. se eee eee 6 . Branches nearly always few-celled and thorn-like, 8—11y in diameter,in, the amnain axis. eee S. stagnatile . Branches elongate, thorn-like branches rare; cells 12-18, in diameter sin’ thesmain, axis] ===. ee ee ee eee S. subsecundum [114] . Filaments slender and graceful, less than 10u in diameter S. tenue pehilamentsestouter 91 4—l'Saminmciamectc rma mes ee alae u sre mene 8 . Main filaments 14-17 in diameter; branches mostly short-pointed; cells of the main axis swollen, 1-2 times the diameter in length_.S. lubricum . Main filaments (12)—14—18 in diameter; cells 4-8 times their diameter in length, cylindrical; branches attenuate candy SethLeK Otis! 15-(16)» in diameter, (21)—48-53-(66) long. Oogonia solitary; globose; operculate; division superior; 40.7-42-(45), in diameter, 44-46-(49), long. Oospores globose; filling the oogonia; wall smooth; 38-43, in diameter, 38-43, long. Antheridia 10.7 in diameter, (5)-6-7-(8)» long. In a roadside fosse. Wis. Oedogonium crispum ( Hass.) Wittrock 1875, p. 10 Pl. 44, Fig. 5 Macrandrous; monoecious. Vegetative cells cylindric, (10)—12-l5pz in diameter, 35-42-(80), long. Oogonia solitary; subglobose or obovoid-globose; operculate; division superior; (37 )—39—-42-(45) » in diameter, 42-50-(53) long. Oospores subglobose; the wall smooth; 35-40-(43)» in diameter, 35-40-(43)» long. Antheridia 8-14, in diameter, 7-12, long. In small pools on beach of lake, Wis., Mich. Oedogonium crispum fa. inflatum Hirn 1900, p. 161 Vegetative cells 12-16, in diameter, 35-95, long. Oogonia obovoid- globose, 40-50» in diameter, 45-53, long. Oospores 37—-45p in diameter, 38-45» long. Antheridia 8-12, in diameter, 9-12 long. Mich. Oedogonium gracilimum Wittrock & Lundell in Wittrock 1875, p. 15 Pl. 34, Figs. 13, 14 Macrandrous; monoecious. Vegetative cells cylindric but often irregular, forming crooked filaments, epiphytic on other species of Oedogonium; (4)-5.2-5.5-(7)» in diameter, 15-22-(42) long. Oogonia solitary; oblong; operculate; division superior; 14-19» in diameter, 34-40» long. Oospores oblong-ellipsoid; not filling the oogonia; 13-17, in diameter, 25-28-(82) long. Antheridia 3-5p in diameter, 5-7,» long. In a roadside fosse. Mich., Wis. Oedogonium Gunnii Wittrock 1875, p. 387 Pl. 34, Figs. 15, 16 Macrandrous; monoecious. Vegetative cells cylindric or slightly capitellate, 6-9.2-(10) in diameter, (16.6 )—20.3-30-(45) long. Oogonia 1-4, depressed-globose; operculate; division median and [ 190 ] narrow (sometimes wide in our specimens); (23 )—25-26-(29), in diameter, (19)-—29-30. long. Oospores depressed-globose; nearly filling the oogonia; wall smooth; 22.5-27y in diameter, 17-18.5—( 23) p long. Antheridia 7.6-9, in diameter, 3.8-11—(12) » long. Attached to grass in a small pond. Wis. Oedogonium inclusum Hirn 1895, p. 21 Macrandrous; monoecious. Described in previous section. Oedogonium Itzigsohnii DeBary 1854, p. 56 Macrandrous; monoecious. Vegetative cells cylindric, 8-10 in diameter, 25-50» long. Oogonia solitary; ellipsoid, with a median whirl of cone-shaped projections; operculate; division inframedian; 34-40 in diameter, 32-40u long. Oospores globose; not filling the oogonia; wall smooth; 20-23. in diameter. Antheridia 8-9, in diameter, 8—15y long. Mich. Oedogonium minisporum Taft 1939, p. 80 Pl. 43, Fig. 1 Macrandrous; monoecious. Vegetative cells capitellate, 6-14, in diameter, 53-69, long. Oogonia 1 or 2; subpyriform-globose to subglobose; operculate, opening median; 30-42» in diameter, 34-42, long. Oospores globose to subglobose; not filling the oogonia; wall smooth (yellow); 25-30, in diameter, 24-29, long. Antheridia 8-11p in diameter, 7-9» long. Presque Isle County, Michigan. Oedogonium minus ( Wittr.) Wittrock 1875, p.9 Pl. 34, Figs. 7-9 Macrandrous; monoecious. Vegetative cells capitellate; walls spirally punctate; (9)-12-13, in diameter, (30)-35-74-(78)y long. Oogonia solitary, globose or pyriform-globose; wall with spiral punctations (in our specimens, with projections, as if mucilaginous concretions had formed at the punctations); operculate; division median; (34)-35-40-(46), in diameter, (28)-30-40-(42)» long. Oospores depressed-globose; not filling the oogonia; wall smooth; 30-35-( 42). in diameter, (26)-30-33-(36) long. Antheridia 9-13, in diameter, 3-5,» long (in series of up to 10). In a roadside fosse. Mich.,Wis. [ 191 ] Oedogonium nodulosum Wittrock 1872, p. 22 Macrandrous; monoecious. Vegetative cells with 2 prominent undulations and constrictions; 20-29. in diameter, 30-140, long. Oogonia 1 or 2; obovoid-globose or obovoid-ellipsoid; operculate; opening superior; 45-57» in diameter, 56-73, long. Oospores globose or subglobose-ellipsoid; nearly filling the oogonia; wall smooth; 46-53, in diameter, 49-56y long. Mich. Oedogonium oblongum Wittrock 1872, p. 2 Macrandrous; monoecious. Vegetative cells cylindric, 6-lly in diameter, 20-86 long. Oogonia solitary; oblong; operculate; division superior; 20-264 in diameter, 41-60, long. Oospores ellipsoid to ovate; not filling the oogonia; wall smooth; 19-23 in diameter, 30-36, long, Antheridia 6-9, in diameter, 7-9 long. Mich. Oedogonium oblongum var. majus Nordstedt in Wittrock 1876, p. 45 Vegetative cells 8-11, in diameter, 35-75 long. Oogonia 26—28y in diameter, 42-50» long. Oospores 22-26 in diameter, 31-34» long. Antheridia 4-9 in diameter, 9-10,» long. Mich. Oedogonium oblongum var. minus Wart 1939; p. 6! Pl. 48, Figs. 2,3 Vegetative cells 3-6, in diameter, 16-35, long. Oogonia 13-16y in diameter, 20-23 long. Oospores 11-15» in diameter, 17-21, long. Antheridia 5-6 in diameter, 7p long. Mich. Oedogonium pachydermum Wittrock & Lundell in Wittrock 1871, p. 125 Macrandrous; monoecious. Vegetative cells cylindric, 21-27» in diameter, 34-120y long. Oogonia solitary (sometimes 2); ellipsoid; operculate; division superior; 50-70p in diameter, 75-100, long. Oospores ellipsoid; not filling the oogonia; wall smooth; 40-60 in diameter, 50-80, long. Antheridia 18-21» in diameter, 10-12» long. Mich. Oedogonium poecilosporum Nordstedt & Hirn in Hirn 1900, p. 298 Macrandrous; monoecious or dioecious. Described in previous section. Oedogonium psaegmatosporum Nordstedt 1877, p. 24 Pl. 34, Fig. 4; Pl. 37, Fig. 6 Macrandrous; monoecious. Vegetative cells cylindric, elongate; 9-10-(14) in diameter, (56)-57—80, long. Oogonia 1-5, pyriform- [ 192 } globose; operculate; division median; (28)-33-39 in diameter 33-40--(43) long. Oospores depressed-globose; nearly filling the oogonia; wall smooth; 27-3lp in diameter, 23-27 long. Antheridia 9-12, in diameter, 6-10-(11.7) long. Our plants seem to belong here, although the vegetative cells are slightly larger than described for this species and the oospores sometimes do not completely fill the oogonia. In a ditch through a Sphagnum bog. Wis. Oedogonia pusillum Kirchner 1878, p. 59 PI. 37, Figs. 11, 12 Macrandrous; monoecious or dioecious. Vegetative cells cylindric, 6» in diameter, (10)-25-50-(60), long; basal cell hemispheric. Oogonia solitary; subbiconic-ellipsoid to subbiconic-globose, with a slight median constriction when mature; operculate; division median; 14-16, in diameter, (15)-20-25 long. Oospores broadly ellipsoid, but deeply constricted in the median portion; wall smooth; 11-13, in diameter, (13)-14-15-(16)» long. Antheridia 3-4 in diameter, 5-6, long. On aquatic vegetation in swamps and ditches. Mich., Wis. Oedogonium pyriforme Wittrock 1875, p. 39 Pl. 34, Figs. 5,6 Macrandrous; monoecious. Vegetative cells cylindric, 13.6-15- (16) in diameter, (48)-74-80-(90)y long. Oogonia solitary; pyriform; operculate; division superior; 40-44.8—(46), in diameter, (44 )—52.6-(60)» long. Oospores usually filling the oogonia and of the same shape; wall smooth; (36)—40-42, in diameter, (36)-—40-44y long. On grass and Eleocharis in soft water lakes. Wis. Oedogonium Reinschii Roy in Cooke 1883, p. 160 Pl. 34, Figs. 1-3 Macrandrous; monoecious. Vegetative cells subellipsoid to hexa- gonal or fusiform, especially the latter shape in the lower portions of the filament; (5)-7.5-8-(11)» in diameter, 8.5-19.2-(24), long. Oogonia 1-2; pyriform-globose; operculate; division median; (17)- 19-20, in diameter, 15-21-(22.8)» long. Oospores depressed-globose; not filling the oogonia longitudinally; wall smooth; (13)-15-18, in diameter, 14—15-(17), long. Antheridia 4~9.5p in diameter, 9-11.4p long. This species was found to be in a reproductive state in several places during August. It is one of the few species of the genus [ 193 ] which can be identified when in the vegetative condition, because ot the distinctive cell shape. Common in many desmid habitats where the water is soft or acid. Mich., Wis. Oedogonium spheroideum Prescott 1944, p. 353 Pl. 38, Figs. 3, 4 Macrandrous; monoecious. Vegetative cells elongate-cylindric, 16-19, in diameter, 115-155, long. Oogonia solitary; broadly ellip- soid to subglobose; operculate; division superior; 55-64, in diameter, 80-87.5, long. Oospores spheroidal, the wall thick, outer membrane with 12-15 longitudinal ribs; 57-60» in diameter, 57-60, long. Antheridia 1-4, immediately below the oogonia or scattered. Anther- ozoids 2; the division horizontal; 19-21, in diameter, 16, long. This species should be compared with Oe. sol Hirn, which is smaller and has an oospore with the middle, rather than the outer, layer of the wall ribbed. Attached to grass in a roadside swamp. Wis. Oedogonium spirostriatum Tiffany 1936a, p. 2 Pl. 44, Figs. 1, 2 Macrandrous; monoecious. Vegetative cells slightly capitellate; 16-24-( 28), in diameter, 50-164, long; wall of the vegetative cells, as well as of oogonia, with spirally disposed punctations; basal cell hemispherical to nearly globose. Oogonia solitary; subglobose to depressed-globose; operculate; division supramedian; 49-56 in diameter, 40-50u long. Oospores depressed-globose, about the same shape as the oogonia but not filling them; 40-47» in diameter, 34-40» long. Antheridia 20-24, in diameter, 17-20, long. This species should be compared with Oe. punctatostriatum, which is dioecious and has cylindric cells; also the oogonium of Oe. punctatostriatum has a median, rather than a supramedian, division. Common in many lakes. Mich., Wis. Oedogonium spurium Hirn 1900, p. 301 Macrandrous; monoecious or dioecious. Described in previous section. Oedogonium trioicum Woronichin 1923, p. 99; 1923a, p. 141 Macrandrous; monoecious or dioecious. Described in previous section. [ 194 ] SECTION 5 Nannandrous—Idioandrosporous—Poriferous Oedogonium cyathigerum Wittrock 1871, p. 181 Nannandrous; idioandrosporous. Vegetative cells cylindric, 2130p in diameter, 40-300» long. Oogonia 1-8; subovate; opening by a superior pore; 57-65, in diameter, (70)-77-100p long. Oospores subovoid or quandrangular-ellipsoid; outer spore wall smooth middle layer with 16-25 longitudinal ribs; 51-62» in diameter, 60-75. long. Dwarf male plants 10-15, in diameter, 50-58, long. In swamps. Mich., Wis. Oedogonium cyathigerum fa. ornatum (Wittr.) Hirn 1900, p. 254 Pl. 44, Fig. 13 A form somewhat larger throughout than the typical plant and with dwarf males more elongate. With the typical plant. Wis. Oedogonium gallicum Hirn 1900, p. 197 Pl. 39, Fig. 4 Nannandrous; idioandrosporous. Vegetative cells cylindric, 16- 18.5-( 22) in diameter, 51-65-(120) long. Oogonia solitary (rarely 2 together); globose; opening by a median or supramedian pore; (39)—45-48, in diameter, 40—-45-(54), long. Oospores depressed- globose; filling the oogonia; wall thick, smooth; 36-46, in diameter, 39-44, long. Dwarf male plants 2-celled, on the suffultory cells. Antheridia exterior, 11.71 in diameter, 10-13, long. Suffultory cell 18, in diameter, 51, long. In waterlily pond. Mich., Wis. Oedogonium hystricinum Transeau & Tiffany 1919, p. 240 Nannandrous; idioandrosporous. Vegetative cells cylindric, 8-l5pz in diameter, 42-100, long. Oogonia solitary; globose or obovoid; opening by a median pore; 30-40» in diameter, 35-53 long. Oospores globose or subglobose; outer wall densely spiny; 23-38, in diameter, 28-43, long. Antheridia 5-6 in diameter, 6-10p long. Mich. Oedogonium idioandrosporum (Nordst. & Wittr.) Tiffany 1934, p. 325 Nannandrous; idioandrosporous. Vegetative cells cylindric, 25-36, in diameter, 65-200» long. Oogonia 1-8; globose-obovoid to globose; [ 195 ] opening by a superior pore; 48-59» in diameter, 57-90, long. Oospores ellipsoid-globose, ovoid, or angular-globose; wall smooth; 42-57 in diameter, 50-66. long. Antheridia 8-10» in diameter, 10-18, long. Mich. Oedogonium irregulare Wittrock 1871, p. 128 Nannandrous; idioandrosporous (?). Vegetative cells cylindric, 15-20. in diameter, 40-8Uz long. Oogonia solitary; globose or subdepressed-globose; opening by a superior pore; 37—45y in diam- eter, 36-47 long. Oospores globose; filling the oogonium; wall smooth; 36-42 in diameter, 34-41, long. Antheridia 10-12, in diameter, 6-8» long. Mich. Oedogonium magnum (Ackley ) Tiffany 1934, p. 325 Nannandrous; idioandrosporous. Vegetative cells cylindric, 14-18p in diameter, 30-90p long. Oogonia solitary; subglobose; opening by a supramedian or median pore; 40-43, in diameter, 33-38, long. Oospores globose to subglobose; wall smooth; 38-41» in diameter, 32-36, long. Antheridia 8-10-(12), in diameter, 8-10,» long. Mich. Oedogonium multisporum Wood 1869, p. 141 Nannandrous; idioandrosporous (or gynandrosporous ?). Vegeta- tive cells cylindric, 10-15y in diameter, 10-30 long. Oogonia 1-3; subovoid or subglobose; opening by a superior pore; 2435p in diameter, 27-33, long. Oospores globose; nearly filling the oogonia; wall smooth; 27-30, in diameter, 24-30y long. Antheridia quadrate, 7-9, in diameter. Mich. Oedogonium perfectum (Hirn) Tiffany 1934, p. 326 [Oe. cyathigerum fa. perfectum Hirn] P3095 Migs: 6, 7, Nannandrous; idioandrosporous. Vegetative cells cylindric, 20- 30-(35) in diameter, (65)-92-350, long. Oogonia solitary (or as many as 4 in a series ); subovate, subquadrangular-ellipsoid, or ovate; opening by a superior pore; (65)—66-72-(85), in diameter, 70-85- (111), long. Oospores obovoid; filling the oogonia; outer spore wall smooth, middle layer ridged with 16-24 anastomosing and curved costae; 59-70-(80)» in diameter, (65)-—70-83-(85) long. Dwarf male plants on the suffultory cells, 12-16 in diameter, 50-58—(85) » long. In swamps. Wis. [ 196 ] Oedogonium Westii Tiffany 1934, p. 325 Pl. 39, Fig. 8 Nannandrous; idioandrosporous (?). Vegetative cells cylindrical or somewhat capitellate, (17)-19.5-29-(35), in diameter, (S1)- 117-163-(180), long. Oogonia solitary or as many as 3 in a series; obovoid or ellipsoid; opening by a superior pore; 53-68, in diameter, 67-99, long. Oospores obovoid or ellipsoid; filling the oogonia; wall smooth; (49)-54.6-65, in diameter, (49)-68.2-81 long. Dwart male plants on suffultory cell. Antheridia 18, in diameter, 13, long. On grass and other submerged aquatics in several soft water and acid lakes. Wis. SECTION 6 Nannandrous—Gynandrosporous—Poriferous Oedogonium Braunii Kuetzing 1849, p. 366 Nannandrous; gynandrosporous. Vegetative cells cylindric, 13-15 in diameter, 25-60, long. Oogonia solitary; ovate or subglobose; opening by a median pore; 30-37» in diameter, 33-43, long. Oospores globose; wall smooth; 27-33, in diameter. Antheridia 5-8» in diameter, 9-10, long. Mich. Oedogonium concatenatum Wittrock 1875, p. 25 Nannandrous; gynandrosporous. Vegetative cells cylindric, 25—40p in diameter, 75-400» long. Oogonia 1-6, subovate or quadrangular- ellipsoid; opening by a superior pore; 63-83, in diameter, 76-105. long. Oospores subovoid or quadrangular-ellipsoid; median wall with pits arranged in longitudinal series; 60-75, in diameter, 67-95p long. Antheridia 13-15, in diameter, 12-25p long. Mich. Oedogonium crassiusculum Wittrock 1871, p. 182 Nannandrous; gynandrosporous. Vegetative cells cylindric, 27-30 in diameter, 95-105» long. Oogonia 1-2; globose-ovate or subglo- bose; opening by a superior pore; 54-60» in diameter, 60-75, long. Oospores ellipsoid-globose or globose; wall smooth, thick; 51-57u in diameter, 52-63, long. Antheridia 7-9, in diameter, 9-16, long. Mich. Oedogonium depressum Prigsheim 1858, p. 69 Nannandrous; gynandrosporous. Vegetative cells cylindric, 5—9p in diameter, 25-54 long. Oogonia solitary (sometimes 2); globose or subglobose; opening by a median pore; 28 in diameter, 26 long. Oospores depressed-globose, not filling the oogonia; wall smooth; 234 in diameter, 17-18, long. Dwarf male plants 4-5p in diameter, 14-16 long. Mich. [197 ] Oedogonium hispidum Nordstedt in Wittrock 1871, p. 128 Pl. 24, Fig. 4 Nannandrous; gynandrosporous. Vegetative cells cylindric, 9-l4y in diameter, 36-1380» long. Oogonia solitary; terminal; subellipsoid or ellipsoid-globose; opening by an inferior pore; 35-44, in diameter, 42-56 long. Oospores globose to globose-ellipsoid; not filling the oogonia; outer wall spiny; 32-39» in diameter, 32-40 long. An- theridia 5-6, in diameter, 7-9p long. Mich. Oedogonium multisporum Wood 1869, p. 141 Nannandrous; gynandrosporous or idioandrosporous. Described in previous section. Oedogonium Sawyerii Prescott 1944, p. 354 Pl. 39, Fig. 1 Nannandrous; gynandrosporous. Vegetative cells cylindric, stout; 30-33.3n in diameter, 66.6-8l long. Oogonia solitary; nearly glo- bose; 63-66.62 in diameter, 55-60 long; opening by a superior pore. Suffultory cell swollen. Oospores globose; outer membrane with a prominent spiral ridge, continuous from pole to pole, the axis of the spore turned at an angle of about 30 degrees from the longitudinal axis of the oogonium; 50-55p in diameter (including ridge). Male plants on the suffultory cell. Antheridia 8-10, in diameter; androsporangia 25.9» in diameter, 14.8» long. This species should be compared with the smaller and idioandro- sporous Oe. latviense (Tiff.) Tiffany and with Oe. spiripennatum Jao, which has a median pore. In a beach pool cut off from a soft water lake. Wis. Oedogonium sexangulare Cleve in Wittrock 1871, p. 131 Pl. 39, Figs. 2,3 Nannandrous; gynandrosporous. Vegetative cells cylindric, (9)- 16-20-(22.6)» in diameter, (33)-39-57-(78) long. Oogonia soli- tary; sexangular-ellipsoid; opening by a median pore; 29-33-(40) in diameter, (33)-34-89, long. Oospores the same shape as the oogonia and filling them; wall smooth; (27)-31p in diameter, (31 )-86-38.7-(40)» long. Dwarf male plants on the suffultory cell. Antheridia exterior, 6-8. in diameter, 9-12» long. Suffultory cell somewhat larger than the vegetative cells. In a lily pond and in acid swamps. Mich., Wis. Oedogonium stellatum Wittrock 1871, p. 129 Nannandrous; gynandrosporous. Vegetative cells cylindric, 15-35, in diameter, 40-225, long. Oogonia 1-3; obovoid-globose; opening [ 198 ] by a superior pore; 51-64, in diameter, 56-70% long. Oospores globose; filling the oogonia; outer wall spirally striated with ribs; 50-58 in diameter. Antheridia 6-9, in diameter, 8-13, long. Mich. Oedogonium subsexangulare Tiffany 1934, p. 325 Pl. 39, Fig. 5 Nannandrous; gynandrosporous. Vegetative cells cylindric, (15)- 19-24 in diameter, (20)-30-(68), long. Oogonia solitary; sexan- gular; opening by a median pore; 35-38-(48), in diameter, (41)- 45-50, long. Oospores the same shape as the oogonia and filling them; 3440, in diameter, (39 )—40—-43-( 48) long; the wall smooth. Dwarf male plants with elongated stipes. Antheridia 6—S» in diameter, 8-10, long. Floating clots of filaments in a small pond. Wis. SECTION 7 Nannandrous—Idioandrosporous or Gynandrosporous—Poriferous Oedogonium Borisianum (LeCl.) Wittrock 1875, p. 25 Pl. 35, Figs. 8,9 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells cylindric, (15)-18.5-24» in diameter, (45)—-55-59—-(140)» long. Oogonia 1-5; obovoid or angularly ellipsoid; opening by a superior pore; (33)—40-50 in diameter, 55-90 long. Oospores obovoid; filling the oogonia in diameter but not in length; wall thick, smooth; (35)-47-49u in diameter, (48)-55.5-57-(60) long. Dwarf male plants on the much enlarged suffultory cell. Antheridia exterior; §-10u in diameter, (11)-12-15-(16), long. Suffultory cell 37, in diameter, 55-(92)» long. Common in several swamps and small lakes. Mich., Wis. Oedogonium echinospermum A. Braun in Kuetzing 1849, p. 366 Pl. 35, Figs. 10, 11 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells cylindric, 18-21-(30) in diameter, (45)-62-130, long. Oogonia depressed-globose or ellipsoid-globose; opening by a median pore; (39)-50-54.6y in diameter, (41)-46—49-(57) long. Oospores globose or depressed-globose; the outer wall furnished with short, sharp spines; (38)—46—47, in diameter, (38)—40-44-( 49)» long. Dwarf male plants on the suffultory cell. Antheridia exterior, 6-9-(12), in diameter, 6-11-(15) long. On overhanging grass in a ditch through a Sphagnum bog. Mich.., Wis. [ 199 ] Oedogonium spiralidens Jao 1934, p. 84 Pl. 40, Fig. 1 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells cylindric, (12)-14-16-(18) in diameter, (50)-55-76—(85)» long. Suffultory cell enlarged, 22.5 in diameter, 70.3» long. Oogonia solitary; globose or obovoid; opening by a median pore; (42)—44— 46—(50) in diameter, (40 )—48—(50) » long. Oospores nearly globose, with long axis transverse to long axis of oogonium; outer spore wall with 4-7 spiral costae, irregularly toothed at the edges, the costae meeting at the poles; wall also marked with coarse granula- tions or crystalline deposits; 41-50, in diameter, 41-47 long. Dwarf male plants 2- or 4-celled; on the suffultory cell; 10-12-(18), in diameter, 62.91 long. Antheridia exterior; 6-7.8-(8)» in diameter, (8)—-11-12y long. Attached to reeds in lakes. Wis. Oedogonium striatum Tiffany 1934, p. 326 Pl. 39; Fig. 10 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells cylindric or slightly capitellate, (18)-30-36, in diameter, (53 )-76-250 long. Oogonia 1-8-(10); subovate or ellipsoid; opening by a superior pore; (67 )—76-80p in diameter, 79-83-(92) » long. Oospores the same form as the oogonia; the outer layer of the spore wall with about 40 longitudinal, anastomosing ribs; 64-72-(76)» in diameter, 74-76-(90) long. Dwarf male plants on the much enlarged suffultory cell. Antheridia exterior; (12)-13.3- 14, in diameter, 9.5-12y long. Suffultory cell 57-68.4, in diameter, 117, long. In a small northern lake among sand hills. Wis. Oedogonium Wolleanum Wittrock 1878, p. 137 Pl. 35, Figs. 12, 18 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells long, cylindric; (21)-25-30, in diameter, (65)-70-180-( 235) long. Oogonia 1-4, ellipsoid or subquadrangular; opening by a superior pore; 58-65-(68), in diameter, (65)-69-80-(89), long. Oospores filling the oogonia and of the same shape; the outer layer of the spore wall furnished with 25 or more ribs with entire margins; (56 )-58-65-(66) in diameter, 65-80.5-(83), long. Dwarf male plants, usually several, on the suffultory cell; 2- or 4-celled. Anther- idia exterior; (9)—10-12-(14), in diameter, (7)—8-10-(11), long. Suffultory cell much enlarged, (45)—48-53-(65) » in diameter. In a small northern lake among sand hills. Wis. [ 200 ] SECTION 8 N annandrous—Idioandrosporous—Operculate Oedogonium Ackleyae Tiffany 1937, p. 70 Nannandrous; idioandrosporous (?). Vegetative cells cylindric, 9-11» in diameter, 27-60 long. Oogonia 1-3; globose or subglobose; operculate; division superior; 32-35, in diameter, 30-35, long. Oospores globose; not filling the oogonia; median wall scrobicuiate; 31-33 in diameter, 31-32. long. Antheridia 8-9» in diameter, 6-10, long. pach Oedogonium brasiliense Borge 1899, p. 4 Pl. 41, Figs. 3, 4 Nannandrous; idioandrosporous. Vegetative cells distinctly capi- tellate, (16)-20.3-22, in diameter, (35 )-55-74—(95)» long. Oogonia 1-4-(9); depressed-globose; operculate; division wide, median or supramedian; 51.8-55.5-(63) in diameter, 46.2-52-(59) long. Oospores globose or depressed-globose; not filling the oogonia; wall smooth; (44.5)—48-53, in diameter, 33-35-(45) long. Dwarf male plants unicellular; on the oogonia; 11, in diameter, 12-13-(19) long. Our specimens differ from the original description of Oe. brasilien- se in having the operculum sometimes supramedian and in having the oogonia in longer series. In a small pond on grass. Wis. Oedogonium Kozminskii Prescott 1944, p. 355 Pl. 42, Figs. 4-6 Nannandrous; idioandrosporous. Vegetative cells cylindric to slightly capitellate, 14-15.6. in diameter, 50-60 long. Oogonia solitary; globose; operculate; division supramedian; (46 )-50.7-52p. in diameter, 46-53.7 long. Oospores globose or depressed-globose; wall smooth; 43.9-45, in diameter, 39-42 long. Suffultory cell not enlarged or scarcely so. Dwarf male plants unicellular; on the oogonia; 11.7-13, in diameter, 13-14.5p long. The distinguishing characteristics of this species are the capitellate vegetative cells and the supramedian opening of the oogonium. It should be compared with Oe. mirandrium Skuja, in which the suffultory cell is enlarged and the oogonium smaller. Attached to grass in a Sphagnum bog. Wis. Oedogonium longatum Kuetzing 1853, Tab. Phyc. 3, p. 11 Nannandrous; idioandrosporous (?). Vegetative cells cylindric, 4-7, in diameter, 10-35y long. Oogonia 1-3; ovate or ellipsoid; operculate; division superior; 16-18, in diameter, 21-25, long. [ 201 ] Oospores ellipsoid, nearly filling the oogonia; wall smooth; 15-17, in diameter, 17-20, long. Antheridia 4-5 in diameter, 5-6y long. Mich. Oedogonium macrandrium Wittrock 1871, p. 130 Nannandrous; gynandrosporous; operculate. Described in the fol- lowing section. Oedogonium megaporum Wittrock 1872, p. 3 Nannandrous; idioandrosporous. Vegetative cells cylindric, 13-17p in diameter, 40-100. long. Oogonia 1-6; pyriform, with 12-16 longitudinal ribs; operculate; division supramedian; 37-42, in diameter, 40-45, long. Oospores subdepressed-globose; not filling the oogonia; wall smooth; 31-35-(38), in diameter, 27-30» long. Dwarf male plants unicellular, 8-124 in diameter, 13-16, long. Mich. Oedogonium polyandrium Prescott 1944, p. 355 P]. 42, Figs. 7-9 Nannandrous; idioandrosporous (?). Vegetative cells slightly capitellate, 4.5-5.4, in diameter, 14-30» long. Oogonia solitary; ovate or broadly ellipsoid; operculate; opening superior; 17-19» in diameter, 27-28, long. Oospores ovate; nearly filling the oogonia; outer spore wall with coarse sparsely arranged scrobiculations or shallow pits; middle and inner layers of the spore wall smooth; 15-17 in diameter, 22-25. long. Dwarf male plants 2-celled, numerous; on the oogonia; stipe 4.5. in diameter, 14-16, long. Antheridia exterior (?). This species has a combination of characteristics which make it quite unlike any other. It should be compared, however, with Oe. longatum, which is similar in size, but in which the outer layer of the oospore wall is smooth. Also in Oe. longatum the dwarf male plants are distinctly curved or reflexed. Skuja (1932, p. 59) describes the oospore wall as having the middle layer pitted. Attached to grass in a bog. Wis. Oedogonium pseudoplenum Tiffany 1934, p. 326 Pl. 40, Fig. 9 Nannandrous; idioandrosporous. Vegetative cells capitellate, (12)- 15.6-16.5-(17)» in diameter, (36)-54.6-120, long. Oogonia 1-8; globose; operculate; division median and wide; 36—40-(42)» in diameter, (36)-389-41-(53), long. Oospores depressed-globose; not filling the oogonia; wall smooth; (30)—31.2-33, in diameter, (27)- 30-31, long. Dwarf male plants unicellular; on the oogonia; 8. in diameter, (12)—14—15y long. In a Sphagnum bog. Wis. [ 202 | Oedogonium sinuatum (Trans.) Tiffany 1934, p. 325 Nannandrous; idioandrosporous. Vegetative cells undulate (with 4 undulate constrictions), (13)-19-26» in diameter, 48-110, long. Oogonia 1-2, subglobose or ellipsoid-globose; operculate; division inferior; 56-68 in diameter, 45-80 long. Oospores globose; not filling the oogonia; wall smooth; 42-60,» in diameter, 42-56, long. Dwarf male plants elongate-obconic, on the suffultory cell. (Typical plant not found in our collections. ) Oedogonium sinuatum fa. seriatum Prescott 1944, p. 354 Pl. 40, Fig. 2 Vegetative cells undulate and capitellate, with 4 median undula- tions; 22-25 in diameter, 48-59.2-(140) long. Oogonia in series of 4 or 5; operculate; division inferior; 62-67» in diameter, 62-72 long. Oospores globose; not filling the oogonia; wall smooth; 55.54 in diameter. Dwarf male plants usually crowded on the suffultory cell. Antheridia exterior (?), 10.9 in diameter. This form has some features resembling Oe. undulatum, with which it should be compared. The principal difference is the seriate arrangement of the oogonia in our specimens. Attached to overhanging grass in a Sphagnum bog ditch. Wis. SECTION 9 Nannandrous—Gynandrosporous—Operculate Oedogonium ambiceps (Jao) Tiffany 1937, p. 79 Pl. 37, Figs. 7-9 Nannandrous; gynandrosporous. Vegetative cells distinctly capi- tellate, (9)-12-13. in diameter, 22-424 long. Oogonia solitary, depressed-globose, with 8-10 median longitudinal bulges separated by narrow creases, or sometimes by broad depressions; operculate; division inframedian; 32—37—(38) in diameter, (19)—29.6—33p, long. Oospores depressed-globose; nearly filling the oogonia; wall thick, smooth; (19)—26—33, in diameter, (19)—25.9—27p long. Dwarf male plants not observed. Androsporangia 11—13, in diam- eter, 4p long. The absence of dwarf male plants from our specimens and the small proportions of the androsporangia make it possible to confuse this with some other monoecious species, but the distinctive form of the oogonium and its markings, together with the gynandrous condition, are helpful in identification. Attached to logs. Wis. [ 203 ] Oedogonium Areschougii Wittrock 1871, p. 122 Nannandrous; gynandrosporous. Vegetative cells cylindric, (8)- 9-12-(13), in diameter, 36-38-(75)» long. Oogonia 1-7; depressed- globose or pyriform-globose; operculate; division median; (34)-35- 37-(39)» in diameter, 36-40» long. Oospores globose; not filling the oogonia; wall smooth; (22)-23-25-(26) in diameter. Dwarf male plants unicellular; on or near the oogonia; 6-7» in diameter, 12-13-(15)» long. In a lily pond. Wis. Oedogonium Areschougii var. contortofilum Jao 1934a, p. 199 Pl. 40, Figs. 6, 7 Somewhat larger throughout (in our specimens) than the typical plant. Vegetative cells slightly capitellate, forming spiral] twists especially just above the oogonial series, in which there may be as many as 7; 7-12-(15.6)) in diameter, 54-60, long. Oogonia 36—-41p, in diameter, 30-31 long. Dwarf male plants unicellular; on the oogonia or near them. Oospores globose, 31p in diameter, 29-30 long. Ree ate variation was noted in the amount of twisting exhibited by this variety in different habitats. The suggestion naturally presents itself that the spiral character of the filaments is related to environmental factors. It is known that reaction to parasitism frequently causes bending in filamentous algae, although in these cases no parasitic organisms were observed. On submerged wood. Wis. Oedogonium ciliatum { Hass.) Pringsheim 1856, p. 227 Nannandrous; gynandrosporous. Vegetative cells cylindric, 14-24, in diameter, 35-921 long. Oogonia 1-7; ovate or ovate-ellipsoid; operculate; division superior to supreme; 43-50 in diameter, 55-72y long. Oospores ovate to subellipsoid-globose; nearly filling the oogonia; wall smooth; 40-47» in diameter, 44-57» long. Antheridia 8—10p. in diameter, 10-11, long. Mich. Oedogonium Croasdaleae Jao 1934a, p. 202 Pl. 41, Fig. 11 Nannandrous; gynandrosporous. Vegetative cells cylindrical, (20)- 25-28-(30) in diameter, 95-105-( 230)» long. Oogonia usually 3-4 in a series (rarely solitary); subovate or ellipsoid (sometimes sub- quadrangular-ellipsoid ); operculate; division superior; (56)-58— [ 204 | 62-(77) in diameter, 86-96-(116)» long. Oospores filling the oogonia and the same shape; outer spore wall smooth; middle layer with coarse, anastomosing, longitudinal costae; (54)—55-62-(73) in diameter, (77)—79-94-(105) long. Dwarf male plants 10-15. in diameter, 55-60-( 62) » long. In a roadside swamp; attached to submerged aquatics in a beach pool. Wis. Oedogonium decipiens Wittrock 1871, p. 126 Pl. 42, Figs. 13, 14 Nannandrous; gynandrosporous. Vegetative cells cylindric or slightly capitellate, (9)-10-12, in diameter, (28 )—-30-78-( 80) » long. Oogonia solitary; subglobose; operculate; division median; (30)- 33-36-(38) in diameter, (27)-30-40» long. Oospores depressed- globose, (25)-28-33-(34) in ‘diameter, (23)-25-28-(30)p long. Dwarf male plants unicellular, 7» in diameter, 13-14-(15), long. In several soft water and acid habitats. Mich., Wis. Oedogonium decipiens var. africanum Tiffany 1929, p. 74 Pl. 41, Fig. 2 Vegetative cells capitellate; filaments frequently twisted; 9-9.2— (13), in diameter, 25-30-(60) long. Oogonia globose; (25 )-29.6— 32 in diameter, (23)-27-28.6. long. Antheridia 6» in diameter, Tp. long. On overhanging grass. Wis. Oedogonium decipiens var. dissimile (Hirn) Tiffany 1937, p. 68 Pl. 42, Figs. 11, 12 Vegetative cells capitellate, 8-11-(14)» in diameter, (20 )-55- (65) long; oogonia (28)-33.3-354 in diameter, (23)-29.6-38» long; oospores (23)-30-(34), in diameter, 21-(30)p long. Andro- sporangium 9.2 in diameter, 8» long. Antheridia 8» in diameter. Common in swamps and lakes. Mich., Wis. Oedogonium hians Nordstedt & Hirn in Hirn 1900, p. 227 Pl. 40, Fig. 10; Pl. 42, Fig. 10 Nannandrous; gynandrosporous. Vegetative cells slightly capitel- late, 9-14.8-(18), in diameter, 37-48-(145) » long. Oogonia 1 or 2; subglobose or subovoid; operculate; division superior; 37-48 in diameter, (40)-45-60—( 80) long. Oospores globose; quite or nearly filling the oogonia; wall smooth; 30-31.4-( 40)» in diameter, 32-34— (40) long. Dwarf male filaments 2-celled, on the suffultory cell. [ 205 } Antheridia exterior, 6-8. in diameter, 5-6. long. Suffultory cell (26)-32-34y in diameter, (46 )-—50-53.6—( 80) » long. Attached to grass in a small northern pond in sand hills. Wis. Oedogonium macrandrium Wittrock 1871, p. 180 Pl. 41, Fig. 1 Nannandrous idioandrosporous (or gynandrosporous?). Vege- tative cells cylindric, 14.8—16—(20), in diameter, 40—51.8—(100) u long. Oogonia 1—4; sub-globose or ovate-globose; operculate; di- vision superior; 36—42, in diameter, (43)—48—154, long. Oospores globose; wall smooth; (31)—34—37, in diameter. Dwarf male plants 2- or 4-celled; stipe 14.8, in diameter, 33.3y long; scattered on the female plant. Antheridia exterior, 7.4—-10» in diameter, 7—10, long. In soft water bog lakes. Mich., Wis. Oedogonium michiganense Tiffany 1927, p. 205 P]. 43, Figs. 9-11 Nannandrous; gynandrosporous. Vegetative cells capitellate, 12- 24u in diameter, 80-160» long. Oogonia 1-7; globose to ellipsoid- globose; operculate; division supreme; 50-64, in diameter, 50-80, long. Oospores globose; sometimes filling the oogonia; wall smooth; 44-60» in diameter. Dwarf males 13-20y in diameter, 40-56, long. Mich. Oedogonium monile Berkeley & Harvey in Hooker 1859, p. 342 Nannandrous; gynandrosporous (?). Vegetative cells cylindric, sometimes capitellate; 9-15» in diameter, 50-160, long. Oogonia 1-8; subovate or subglobose; operculate; division superior; 80-39 in diameter, 30-56 long. Oospores globose or subglobose; outer spore wall smooth, median wall scrobiculate; 28-38, in diameter. Antheridia quadrate, 7» in diameter. Suffultory cell 21—29—(32) p in diameter. Mich. Oedogonium oelandicum Wittrock 1875, p. 17 Nannandrous; gynandrosporous. Vegetative cells capitellate, 10— 15, in diameter, 25-125, long. Oogonia 1-7; depressed-globose, with 12-16 prominent longitudinal ribs in the median portion; operculate; division supramedian and broad; (29)-31-40p in diameter, 25-32y long. Oospores depressed-globose; almost completely filling the oogonia; wall smooth; 25-36, in diameter, 23-30, long. Dwarf male plants unicellular; on the oogonia; 7-8, in diameter, 12-15, long. Mich. [ 206 | Oedogonium oelandicum var. contortum Prescott 1944, p. 355 Pl. 42, Figs. 1-3 A variety differing from the typical by its contorted filaments which sometimes form short spirals, several of which may occur in one filament. Vegetative cells 11-12 in diameter, distinctly capi- tellate. Oogonia much shorter than wide; depressed-globose; 29-30, in diameter, 20-21.5. long. Oospores depressed-globose; the wall smooth; 25-271 in diameter, 18-20» long. Dwarf male plants unicellular; on the oogonia. Attached to grass in small lakes. Wis. Oedogonium rugulosum Nordstedt 1877, p. 28 Pl. 44, Figs. 14, 15 Nannandrous; gynandrosporous. Vegetative cells cylindric, (4)- 8-9.5. in diameter, (10)-11.7-19.5-(35) long. Oogonia solitary (rarely 2 together); ellipsoid or globose-ellipsoid; operculate; di- vision superior; (16)—20, in diameter, (22)-25.4-29, long. Oospores globose or subglobose; wall smooth; 15-17.5-(18) in diameter, 17.5-19.7-(25)» long. Dwarf male plants short; on the oogonia. Antheridia exterior, 5. in diameter, 6 long. Basal cell of female filament 7.8» in diameter, 11-13.6-(14)» long. In a roadside fosse. Mich., Wis. Oedogonium rugulosum fa. rotundatum (Him) Tiffany 1936, p. 169 Pl. 89, Figs. 9, 11, 12 Vegetative cells cylindric or slightly capitellate, 5-6.8-(8) in diameter, 27-30-(31) long. Oogonia 1-3; ovate or globose-ellipsoid; division superior; (19)-20-23-(30), in diameter, (20)-29-30, long. Oospores globose or ellipsoid-globose; nearly filling the oogonia; wall smooth; 18-20—(22), in diameter, 22-25, long. Our plants are in agreement with this variety except that the cells have a tendency to be capitellate. With the typical plant. Wis. SecT1on 10 Nannandrous—Idioandrosporous or Gynandrosporous—Operculate Oedogonium acrosporum DeBary 1854, p. 47 Pl. 41, Fig. 7 Nannandrous; gynandrosporous or idioandrosporous. Vegetative. cells cylindric, (12)—15-19.5-(21), in diameter, (34)—40-68-(125) » long. Oogonia solitary; ellipsoid; terminal; wall ridged internally [ 207 ] with 23-30 longitudinal ribs; operculate; division superior; (30')- 35-48, in diameter, 50-63, long. Oospores filling the oogonia, with as many ridges on the membrane as the ribs on the wall of the oogonia, and fitting in between them. Dwarf male plants 2 to 4 cells long, the stipe elongate; 2- or 3-celled; attached to the suffultory cell, Antheridia exterior, 7» in diameter, 11, long. This species is separated from its varieties mostly by the stout suffultory cell and by the somewhat longer oogonia, with more ridges. Common in several lakes and Sphagnum bogs. Wis. Oedogonium acrosporum var. boreale Wolle 1887, p. 84 Vegetative cells 7.8-12u in diameter, 54.6-140, long. Oogonia elliptical, with 11-15 longitudinal ribs; 30-3lp in diameter, 44-46y long. Dwarf male plants 2-celled. Antheridia exterior, 9» in diameter, 11, long. Suffultory cell 15.6, in diameter, 39, long. In acid and soft water lakes. Wis. Oedogonium acrosporum var. bathmidosporum (Nordst.) Hirn 1900, p. 246 Pl. 41, Figs. 5,6 Vegetative cells (8)-12-17p in diameter, 46-54-(125), long. Oogonia with few ridges (about 18 in our specimens); thick and sometimes interrupted; 27.3-80—( 40)» in diameter, (37)-39-59, long. Dwarf male plants 2-celled; on the suffultory cell, which is enlarged to 22. Antheridia exterior, 5-8—(10)» in diameter, 9-12—(18) » long. Specimens collected in Wisconsin have the characteristics of this variety except that the ribs are not crenulate as originally described for it. Common in several lakes and Sphagnum bogs. Mich., Wis. Oedogonium acrosporum var. majusculum Nordstedt 1878, p. 21 Pl. 41, Fig. 10 Vegetative cells relatively longer; (14)—16-20-(21), in diameter, 50-125-(165) long. Oogonia 45-58. in diameter, 50-65.5—-(70) long. Oospores 46-55» in diameter. Attached to grass in a ditch through a Sphagnum bog. Mich., Wis. Oedogonium macrospermum West & West 1897a, p. 472 Pl. 41, Fig. 12 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells cylindric, (10)-16-18.5, in diameter, (80)-55-57—(80) » long. Oogonia solitary; subglobose; operculate; division median; (39)- [ 208 ] 40-44.4-(46) in diameter, 35-38-(44) long. Oospores depressed- globose; with a smooth wall; 36-38.5-( 44) in diameter, (32)-36.5- 42u long. Dwarf male plants short; usually 2-celled; on the suffultory cell. Antheridia exterior; stipe of dwarf male 9-14.81 in diameter. Antheridia 7-10, in diameter, (6 )-11—16—( 22), long. On submerged aquatics in shallow water of a slough. Mich., Wis. Oedogonium subplenum Tiffany 1934, p. 326 Pl. 40, Fig. 8 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells slightly capitellate, (7)-8-12. in diameter, 23-80, long. Oogonia solitary; depressed-globose or pyriform-globose; operculate; division median; 29-35-(38) in diameter, (26)-29-33-(41), long. Oospores globose; not filling the oogonia; 21-22.4—(28) in diam- eter, 19-26 long. Dwarf male plants 1-celled; on the oogonia; 6-7p in diameter, 6-10, long. In shallow water at edge of a Sphagnum bog. Wis. Oedogonium undulatum (de Bréb.) A. Braun in DeBary 1854, p. 94 Pl. 40, Figs. 3-5 Nannandrous; gynandrosporous or idioandrosporous. Vegetative cells capitellate and 4-undulate, except the basal cell which is elongate and smooth; 15.6-18-(22), in diameter, (15.8)—45-100- (110) long. Oogonia solitary (sometimes 2 together); globose or ellipsoid-globose; operculate, the division inferior; (48)-50.7-55, in diameter, (50)-54.6-56-(75) long. Oospores globose; filling the oogonia; wall smooth; 42-50 in diameter. Dwarf male plants on the suffultory cell or nearby. Antheridia interior; 9» in diameter. Very common in many soft water and acid habitats. Mich., Wis. Oedogonium undulatum fa. senegalense (Nordst. ) Hirn 1900, p. 261 Pl. 44, Fig. 4 Vegetative cells with 3 median undulations and of somewhat narrower proportions than in the typical plant; 18-20, in diameter, 48-80» long. Oospores 38, in diameter. Attached to overhanging grass in a ditch through a Sphagnum bog. Wis. ORDER CHLOROCOCCALES This large order is composed of a great variety of plants which are l-celled or which form colonies of rather definite shape. The [ 209 ] cells may be adjoined or merely inclosed by a colonial mucilaginous envelope. In a few forms the cells are connected by strands formed by the remains of old mother-cell walls. The chief characteristic which all forms have in common is a negative one, namely, the inability to multiply by cell division in the vegetative state. Auto- spores are common in vegetative reproduction, as is also the habit of forming daughter colonies within each cell of a mature colony. Zoospores are used by some forms in asexual reproduction and isogametes are the rule in the genera which have sexual reproduc- tion. The cells vary widely in shape, being globose, ovate, acicular, fusiform or polyhedral. Although most forms are uninucleate, a few are coenocytic and hence are regarded by some phycologists as the likely ancestors of the Siphonales. The form of the chloroplast varies almost as much as the cell shape. There may be numerous ovate discs, parietal plates, networks, or in some genera cup-shaped chloroplasts. Pyrenoids may be lacking, but usually there are 1 to several. One family, the Endosphaeraceae, is unique in being diploid in the vegetative state. Key to the Families 1. Unicellular, relatively large, and irregular in shape; wall very wide, lamellated, and not uniform in thickness; inhabiting the tissues of higher plants, or free-living _____ ENDOSPHAERACEAE 1. Unicellular or colonial; cells varied in shape but not irregular; wall of uniform thickness and not definitely lamellated; free-living or attached, rarely ‘subaenialwiss “hee ee ee 2 Ov Pree-foating, or adherentoon) soil = 6 eee 3 2. Attached and sessile, unicellular; cells fusiform — CHARACIACEAE 3. Cells cylindrical and forming a macroscopic network, or triangular or polyhedral and united to form either a flat and circular, or globose coenobium (colony) HYDRODICTYACEAE 8. Cells not cylindrical, and not forming colonies as above... eae 4 4. Unicellular, solitary or sometimes gregarious, free-floating (usually on moist soil if adherent), reproducing by zoospores (rarely aplan- ospores) which do not adhere to one another but which are liber- ated separately from the parent cell (See Chlorella OWE VET) MUN eects tras tet Rl ane akan Ant idli::ARRe baker ee nare inl enis3 Lance tat CHLOROCOCCACEAE 4.) Colomial:, or ‘solitary not, reproducing as ‘aboyes.)..1..5...022s0.sccseasenee- 5 5. Thallus a hollow, globular coenobium of spherical or pyramidal cells, adjoined to neighboring cells by processes, rarely by direct contact. Baie Waser BaeY Se 2 COELASTRACEAE em hvallnasy mOtRAS Ta DOV Case) ec Theo ENN oad See al acl ae) 6 6. An irregular mass of mucilage, often darkly colored, containing ovate or spherical cells at the periphery (compare with Dimorphococcus in the Oocystaceae ) BOTRYOCOCCACEAE GRIN te cas eu Ve ce 2 a FD A a ra a Pate ese 7 7. Cells solitary or in colonies of definite or indefinite shape; cells variable in torm (spherical, ovate, lunate, polyhedral, etc. ), not adjoined to one another; reproduction by autospores____ OOCYSTACEAE 7. Two to eight cells adjoined together or adherent to form a pattern of definite shape (a linear series, stellate, or cruciate ); reproduction by the formation of autocolonies within the cells of the parent coenobium_——_-___ SCENEDESMACEAE FAMILY CHLOROCOCCACEAE In this family the cells vary in shape from spherical to fusiform or spindle-shaped (represented in our collections by spherical cells only ). The family is characterized by the use of zoospores in asexual reproduction. These escape through a pore in the wall and separate immediately. In some forms arrested zoospores (aplanospores ) may function. The plants are mostly solitary and free-floating, but in one genus (Chlorococcum) cells are gregarious and sedentary, inhabiting moist soil or other subaerial habitats. The cell wall may be smooth or spiniferous. There is considerable variation in the form of the chloroplast which may be a parietal or massive cup, or axial and stellate, with 1 or more pyrenoids. In some species the cells become much enlarged and in age multinucleate. In the identification of members of this family a comparison should be made with similarly shaped plants in the Oocystaceae. Key to the Genera 1. Cells spherical or subspherical, inclosed in a wide, longitudinally striated, spindle-shaped sheath. Desmatractum i Gells'spherieal, not inclosedimiasheath= 2 2. Cells free-floating, solitary, the walls setiferous _._.-_______ 3 2. Cells sedentary, or rarely free-floating, solitary or gregarious on moist earth or submerged substrates; wall smooth ._-_-_ = Chlorococcum 3. Setae gradually tapering from the base to apex Golenkinia 8. Setae thickened for a short distance in the basal portion, then abruptly narrowed and tapering to apex Acanthosphaera CHLOROCOCCUM Fries 1825, p. 356 Cells spherical, solitary or more often gregarious in amorphous gelatinous clumps, or forming films on moist or submerged sub- strates; cell wall thin and undecorated; chloroplast a thin parietal plate covering the wall or nearly so, containing 1 pyrenoid; repro- duction by 8-16 oblong zoospores with 2 flagella. Species of Chlorococcum should be compared with Chlorella. See note under that genus. [ 211 ] Chlorococcum humicola (Naeg.) Rabenhorst 1868, p. 58 PI. 45, Fig. 1 Cells spherical, solitary or in small clumps, variable in size within the same plant mass; cells 8-20—( 25)» in diameter. This species is luxuriantly represented on and about dead fish and animal wastes along shores, forming green films in association with Scenedesmus spp. and Euglena spp. Common on beach soils and in moist aerial habitats. Mich., Wis. Without a doubt, another common species, C. infusionum (Schrank) Meneghini occurs in our region. It has larger cells than C. humicola (15-45, in diameter) and is ordinarily found on sub- merged substrates. DESMATRACTUM (West & West) Pascher 1930b, p. 651 Cells globular, the wall thin, firm, and smooth, inclosed in a wide, transparent or brownish spindle-shaped sheath which is longitud- inally striated; and composed of 2 top-shaped halves which adjoin at the midregion of the spindle; chloroplast solitary, a parietal cup with 1 or 2 pyrenoids; reproduction by biflagellate zoospores or by autospores. This genus, as Bernardinella, was once placed in the Heterokontae. Desmatractum bipyramidatum (Chod.) Pascher 1930b, p. 654 Pl. 46, Fig. 9 Characteristics as described for the genus; cells (with sheath) 12 in diameter, 22y long. In acid waters; Sphagnum bogs. Mich. ACANTHOSPHAERA Lemmermann 1899a, p. 118 Unicellular, spherical; free-floating; wall uniformly beset with 24 long, needle-like setae arranged in 6 tiers, 4 in each tier, about the cell wall; setae thickened for about 14 their length from the base, then abruptly narrowed to form slender spines; 1 parietal, lobed chloroplast, covering most of the cell wall, with 1 pyrenoid. Acanthosphaera Zachariasi Lemmermann 1899a, p. 118 Pl. 45, Figs. 4, 5 Characteristics as described for the genus; cells spherical with numerous long setae with thickened bases; cells 9-14.5 in diameter without setae; length of setae 30-35p. In plankton. Wis. [ 212 ] GOLENKINIA Chodat 1894, p. 305 Cells spherical, solitary and free-floating, the wall furnished with long, slender tapering setae; false colonies sometimes formed by the interlocking of setae; cells rarely inclosed by a thin, mucilaginous envelope; chloroplast a parietal cup covering most of the cell wall, containing 1 pyrenoid; reproduction by autospores and zoospores. This genus seems to belong with the Oocystaceae, and it should be compared with spherical members of that family. The justification for placing it with the Chlorococcaceae is the report that zoospores are formed in asexual reproduction, a method not used by the Oocystaceae. Key to the Species Cells 15-184 in diameter; setae 12-18 long G. paucispina Cells 7-15u in diameter; setae 25—45u Via oks oe I be ee et G. radiata Golenkinia paucispina West & West 1902, p. 68 Pl. 45, Fig. 2 Spherical, free-floating unicells with a few short setae arising from all sides of the cell wall; 1 cup-shaped chloroplast, with 1 pyrenoid; cells 15—18, in diameter; setae about 16, long. Rare, in the plankton of several lakes. Wis. Golenkinia radiata (Chod.) Wille 1911, p. 57 Pl. 45, Fig. 3 Spherical, free-floating unicells with long and very slender setae; cells usually solitary but often in false colonies of 4 as a result of the interlocking of the setae; cells 7-15, in diameter; setae 25-45, long. Rare; in euplankton. Mich., Wis. FAMILY ENDOSPHAERACEAE In this family the plants are unicellular, large, irregularly oblong or ovate in shape, free-living, parasitic, or (in our region) endo- phytic, embedded in the tissues of higher plants or in the mucilage of other algae. The chloroplasts are parietal in young cells but be- come massive and axial in older plants, with several pyrenoids. The wall is thick and lamellate, or has knob-like elongations. The family is unique in that the single cells are diploid, being but enlargements of the zygospore formed by the union of isogametes. Reduction division occurs when the cell contents divide to form as many as 256 biflagellate protoplasts. It is possible that zoospores, as well as gametes, are produced in this way. [ 213 ] Key to the Genera Inhabiting ‘the tissues of Lemnass =) San eee Chlorochytrium Free-living or embedded in the mucilage of other algae ______ Kentrosphaera CHLOROCHYTRIUM Cohn 1875, p. 102 Unicellular, oblong or broadly ellipsoid, often irregular in outline, formed when a zygote germinates and sends a tubular elongation into the tissues of Lemna, the cell contents migrating into the tube and then enlarging among the host cells, the entrance tube persisting as a knob-like extension of the wall, which is thick and lamellate; chloroplast at first parietal, later becoming radial and massive; reproduction by division of the cell contents into a large number of biflagellate isogametes or zoospores. Chlorochytrium Lemnae Cohn 1875, p. 102 Pl. 45, Figs. 6,7 See characters of the genus; cells broadly ellipsoid or ovate, with 1 or more knob-like extensions; wall thick and lamellate; cells 60- 100, in diameter, inhabiting the tissues of Lemna trisulca. In host plants collected from water of marshy lakes; in roadside swamps. Mich., Wis. KENTROSPHAERA Borzi 1883, p. 87 Unicellular, often crowded and intermingled with other algae, sometimes living in the mucilage of colonial Myxophyceae; cells irregularly ovate, ellipsoid, or sub-cylindric; walls lamellated, irreg- ularly thickened with knob-like outgrowths; chloroplast axial, with extensions flattened at the wall to form irregularly shaped processes; one pyrenoid. Kentrosphaera gloeophila (Bohlin) Brunnthaler 1915, p. 68 Pl. 45, Figs. 8-10 Characters of the genus; cells broadly ovate, or ovoid or elliptic, with knob-like thickenings of the lamellate wall, 18-20, in diameter, 25-30u long. (For a discussion of the nomenclature of this species see Moore, 1917; G. M. Smith, 1983; Bristol, 1920. ) Among thick clots of blue-green algae. Wis. FAMILY CHARACIACEAE This is a small family of which there is but a single genus (Characium) represented in our collections. ( Actidesmium, reported from California and arctic Alaska, has spindle-shaped, free-floating [ 214 ] cells which are arranged in stellate clusters, adjoined to form com- pound colonies by gelatinous strands.) Characium, which is much more common, has spindle-shaped or ovoid cells growing on other algae, on submerged aquatic plants, or on microfauna. There are 1 or more parietal chloroplasts, each with a pyrenoid (sometimes several). The cells are mostly uninucleate. Biflagellate zoospores, formed 2-128 in a cell, escape through an apical or lateral pore. CHARACIUM A. Braun in Kuetzing 1849, p. 208 See characteristics as described for the family; cells variously shaped, ovoid, fusiform, or cylindric, attached to a substrate (sub- merged plants, larger algae, microfauna) by a stipe (usually) and often with a basal attaching disc; rarely sessile; chloroplasts 1 or several parietal plates which sometimes become diffuse; pyrenoids 1 to several, although rarely there are none; food reserve in the form of starch. Key to the Species 1. Cells epizoic on crustacea, often specific as to host -__.-_----------------_-_---- 2 1. Cells epiphytic on miscellaneous plants but especially Gry HAUIeR Osi Al gag wise ies ewe tage dre gs Cote ea Ae 5 ame clisnrounGee cat the apes. 1.0 restive on ther ee 3 2~ Cells narrowed to-aispinejatithe apex, <= en ee 4 3. Cells broadly ovoid or pyriform, on a short stout stalk. C. Debaryanum 8. Cells elongate-ellipsoid or narrowly obovoid_.......-.--_----.---.. C. Hookeri 4. Cells fusiform or slightly crescent-shaped, on a long, needle-like stipe without a holdfast at the base _________.-..--.-..--------------- C. limneticum 4. Cells elongate-cylindric, from a stipe which has a forked hizoidal sholdfast. 22-04 5 Se C. gracilipes 5. Cells broadly pyriform or broadly ovate, or ovoid —.._.__-__-__---____-_-- 6 5. Cells narrowly ovoid, fusiform, lanceolate, falcate or cylindrical 8 6. With a very slender stipe, 1 to 1} times as long esa reyes) || oo ht Sis aU es Vaca), See C. stipitatum 6. With a stout stipe, much shorter than the length of the cell body a 7. Cells broadly ovate, 10-12 wide____-_-___-__ C. obtusum Weg @ells pyxitorm, 1d—loy widest C. operculum 8. Cells elongate-fusiform, narrowed anteriorly but bluntlyazcunded atthe tap. C. Rabenhorstii 8. Cells lanceolate, falcate, or cylindric, ending in anvapiculation Oryspine ssc. se... ite 2 os sul 9 9. Stipe enlarged at the base to form an attaching disc ____________________- 10 O. 7Stipenwithout apbasalvattachmp dise < e 12 IOs Cells straight,cerect, the stipe short 22s C. Pringsheimii 1G. Gellsystrongly7curved ormalleate .=2 52 PE 11 I, ‘Gells: lanceolate or faleate: = spss Oe UPR ele C. rostratum 11. Cells broadly and unsymmetrically ellipsoid, convex on one margin, nearly straight on the other_____---_-_______. C. ornithocephalum [ 215 ] 12. Cells fusiform, oblong or ovate, straight or nednly(so == 13 12. Cells strongly curved —_—_-————————-—————— == 14 13. Cells 15—20u in diameter_____------------------------—----------------___- C. acuminatum 13. Cells 4-8» in diameter___-.---.----------—--------------------------------------- C. ambiguum 14. Stipe stout and tubular, with irregular margins C. curvatum 14. Stipe long and slender_______---________----_- C. falcatum Characium acuminatum A. Braun in Kuetzing 1849, p. 892 Pl. 46, Fig. 7 Cells oblong or narrowly ovate, narrowed anteriorly to form a short apiculation, acuminate; stipe short; cells 15-20» in diameter, 35-40 p long. Attached to filamentous algae. Mich., Wis. Characium ambiguum Hermann 1863, p. 26 Pl. 45, Fig. 11 Cells solitary, lance-shaped, fusiform or ensiform, narrowed to a sharp point anteriorly, tapering posteriorly to a fine hair-like stipe, without an attaching disc; chloroplasts 1-3; cells 4-8, in diameter, 25-30, long. Attached to filamentous algae; tychoplanktonic. Mich., Wis. Characium curvatum G. M. Smith 1918, p. 641 Pl. 45, Figs. 12, 13 Cells lunate or sickle-shaped, either sharply or bluntly pointed; stipe stout, without an attaching disc; chloroplast with or without a pyrenoid; cells 3-6, in diameter, 13-22 long, including stipe. Epiphytic in the mucilage of colonial algae; tychoplanktonic. Wis. Characium Debaryanum (Reinsch) DeToni 1889, p. 628 Pl. 46, Fig. 19 Cells oblong or ovoid, broadly rounded anteriorly, narrowed below into a stout stipe with a basal adhesive disc or swelling; cells 20-25, in diameter, 30-40, long. Epizoic on copepods. Mich. Characium falcatum Schroeder 1898, p. 23 Pl. 45, Fig. 14 Cells sickle-shaped, ending in a long sharp point; stipe long and slender, without an attaching disc; 1 chloroplast without a pyrenoid (?); cells 4.2-6.5p in diameter, 36-50, long. This species is somewhat like C. rostratum but is separable on the basis of the attaching disc which that species possesses. Also, C. [ 216 ] falcatum has a long, colorless apical beak not present in the former species. It should be compared also with Characiopsis longipes. On filamentous algae in shallow water of lake margins; swamps. Mich., Wis. Characium gracilipes Lambert 1909, p. 65 Pl. 45, Fig. 16 Cells elongate cylindric, straight or very slightly curved, abruptly tapering anteriorly and extended to form a long, hyaline hair, and abruptly tapering below to a slender stipe with 2 or 3 fine, rhizoidal branchings at the base; chloroplasts variable, 1-32 in number with a single pyrenoid in each; cells 5-14» in diameter, (70)-80-480, long. Epizoic on the anterior appendages of crustacea. Mich., Wis. Characium Hookeri (Reinsch) Hansgirg 1888, p. 128 PI. 45, Fig. 17 Cells mostly gregarious on Cyclops, club-shaped to subcylindric; stipe long or short, without an attaching disc; chloroplast 1, with 1-3 pyrenoids; cells 9-12. in diameter, 27-30, long. On Cyclops in lakes and ponds; euplanktonic and tychoplanktonic. Wis. Characium limneticum Lemmermann 1903c, p. 81 Pl. 45, Fig. 18 Cells fusiform or lunate (rarely almost straight), extended an- teriorly into a long, sharp, spine-like tip, tapering posteriorly rather abruptly to form a long narrow stipe, without a basal attaching disc; chloroplasts 1-8, arranged to form a series of parietal bands; cells 5—14p in diameter, 25-110, long, including stipe. Epizoic on Diaphanosoma brachyura in lakes. Mich., Wis. Characium obtusum A. Braun 1855, p. 39 Pl. 45, Fig. 20 Cells oblong-ovate; stipe short and fairly thick; cell rounded anteriorly and furnished with a thickened plug at the apex; chloro- plast parietal, with a single pyrenoid; cells (8)—10—12» in diam- eter, 12.9—14.8—(33), long. Attached to filamentous algae; lakes and Sphagnum bogs. Mich., Wis. Characium operculum Ackley 1929, p. 304 Pl. 46, Fig. 18 Cells broadly pyriform on a short thick stipe with a basal attaching disc, broadly rounded anteriorly and furnished with an [ 217 ] apical thickened plug; chloroplast (?); cells 13-15p in diameter, 19-24y long. On filaments of Desmidium. Mich. Characium ornithocephalum A. Braun 1855, p. 42 Pl. 46, Fig. 14 Cells broadly and unsymmetrically ellipsoid, convex on one side, nearly straight on the other, abruptly narrowed anteriorly to form a sharp apiculation, the cell body set at an angle and curved away from a long stipe with a basal attaching disc; chloroplast laminate, parietal, with a conspicuous pyrenoid; cells 25-33p long, without stipe. on submerged plants, especially filamentous algae. Mich. Characium Pringsheimii A. Braun 1855, pp. 37, 106 Pl. 45, Fig. 21 Cells narrowly elongate-ovoid to fusiform, erect but with a short oblique tip; stipe short; chloroplast a laciniate plate with | pyrenoid; cells 7.8-9, in diameter, 13-16 long. Attached to Tribonema filaments in a roadside fosse. Mich., Wis. Characium Rabenhorstii DeToni 1889, p. 625 Pl. 46, Fig. 27 Cells elongate-fusiform or lanceolate; narrowed anteriorly but with a bluntly rounded apex; narrowed below to a long slender stipe, about % the length of the cell body, with a brown basal attaching disc; cells 8-9, in diameter, 16-18y long. On filamentous algae. Mich. Characium rostratum Reinhard 1876, ex Printz 1914, p. 41 Pl. 45, Figs. 22, 23 Cells lanceolate-faleate with curved apex; stipe long and slender from an attaching disc; chloroplast laminate, nearly covering the entire wall; cells 7.81 in diameter, 40-45» long, including the stipe. Attached to Tribonema filaments in a roadside fosse. Mich., Wis. Characium stipitatum (Bachm.) Wille 1911, p. 45 Pl. 45, Fig. 15 Cells ovate to subspherical or pyriform; stipe slender and tapering from the base of the cell, without an attaching disc; chloroplast parietal along the apical wall, with 1 pyrenoid; cells 5-8» in diam- eter; stipe 10-16, long. Epiphytic on Coelosphaerium Naegelianum; generally distributed. Mich., Wis. [ 218 ] FAMILY HYDRODICTYACEAE The members of this coenocytic family are morphologically very distinctive, although extremely variable. All forms are free-floating, but some are found only in the tychoplankton. In one genus, Hydrodictyon, there are cylindrical cells arranged to form a mac- roscopic, closed cylindrical net. In other genera the cells are triangular or polyhedric in outline and are arranged to form flat or spherical coenobia. The number of cells in the colony varies from 2 to 64 in the plate type of colony, whereas in Hydrodictyon several hundreds of cells are involved, always in multiples of 2. The chloroplast is parietal, either a continuous or perforate sheet, with 1 to many pyrenoids. Like other families in this order, vegetative reproduction by cell division does not occur. The most common method of reproduction is by the formation of daughter colonies within the parent cell, these developing from retained zoospores. Sexual reproduction is by biflagellate isogametes. Key to the Genera 1. Thallus a cylindrical closed reticulum of cylindrical cells which form: 5-sor 6-sided: meshes. Hydrodictyon ienhiallussnotparcyundiscal. nee a= 5 4. ane et eo ES oa 2 2. Thallus composed of 2 triangular or trapezoidal cells with PRG Er MASE Siac IR eel esa cf Euastropsis 2P Shallus composed of more than 2.cells <2. = 20 3 3. Thallus a flat, circular plate of polygonal cells ...___»____ Pediastrum 3. Thallus a spherical colony of spine-bearing cells on stalks radiating. tom a common center... 2 Sorastrum HYDRODICTYON Both 1800, p. 531 Thallus macroscopic, composed of cylindrical cells which are adjoined at their ends to form a cylindrical net with 5- or 6-sided meshes; chloroplast at first a parietal plate with a single pyrenoid, later becoming a reticulum covering the entire wall and containing many pyrenoids; cells multinucleate. Hydrodictyon reticulatum (L.) Lagerheim 1883, p. 71 Pl. 47, Fig. 1 Characteristics as described for the genus; cells up to 200, in diameter, as much as 1 cm. long when fully enlarged, forming a net up to 2 dm. in length; chloroplast a much diffused reticulum, light yellow-green color in the plant mass, especially at maturity. This is a plant which prefers quiet water and is found in lakes where there is little wave action, in pooled streams, and in the [ 219 ] shallow water of swamps and marshes. Its rapid rate of reproduction (daughter nets formed within each cell of the parent net) makes it possible for H ydrodictyon to develop luxuriant growths in favorable habitats. Thick floating mats often result, and sometimes unbal- anced biological conditions are produced. In some sections it becomes an obnoxious weed, clogging filters, drains, etc. It is so definitely confined to hard water that it may be used as an index organism for a high pH. In the far West it finds ideal growing conditions in the alkaline water of irrigation reservoirs and ditches. Common in a large number of lakes, mostly hard water; generally distributed. Mich., Wis. EUASTROPSIS Lagerheim 1895, p. 20 Thallus free-floating, composed of 2 flattened, triangular or trapezoidal cells adjoined along one wall, the lateral free margins converging and slightly concave, the apex deeply notched; chloro- plast 1, parietal, with 1 pyrenoid. Euastropsis Richteri (Schmidle) Lagerheim 1895, p. 20 Pl. 47, Fig. 2 Characters as described for the genus; cells 4.5-25p in diameter, 5-20p long; 2-celled colony 4.5-25 wide, 10-40» long. Rare, in plankton. Wis. PEDIASTRUM Meyen 1829, p. 772 Coenobium a free-floating, circular, monostromatic disc of cells which may be continuous or perforate; peripheral cells of the disc with 1 or 2 lobes or processes, or merely emarginate without processes; interior cells either the same shape as the marginal ones or different; chloroplast a parietal reticulum, covering the wall, with 1 pyrenoid; cells multinucleate. Because the plates of Pediastrum are formed by the juxaposition of zoospores developed within a vesicle which is extruded from the mother cell, it not infrequently happens that irregularly formed or abnormal coenobia develop when the zoospores fail to align them- selves in one plane. Hence coenobia may be found in which some cells overlie others. For a criticial study of this genus the reader is referred to Bigeard (1933) and Harper (1916, 1918). Key to the Species 1, Outer free wall of the peripheral cells extended to form a sinple,‘horn-like projection. 2s eee P. simplex 1. Outer free wall of peripheral cells with 2 to 4 projections, or merely ‘emarginate; not forming. processes... ee 2 [ 220 ] . Outer free walls of peripheral cells deeply incised or emarpinate todform 2 to 4 processes eee 5 . Outer free walls of peripheral cells not incised or lobed; processes, if any, only prominent undulations or knob-like thickenings on the wall 3 . Peripheral cells quadrangular-rhomboid, 5-6 sided, the outer margins bearing 1-2 stump-like projections == P. integrum sebernipheral) cellsenor tas: above ste serene is stadt 1 Sot ele a 4 . Peripheral cells with a single emargination, throwing the margin of the colony into a series of undulations. P. muticum . Peripheral cells with 2 shallow emarginations, forming 8 lobes which do not project beyond the periphery of the colony. P. Braunii . Lobes of the peripheral cells not in the same plane, but one above the other as seen in surface view... P. Kawraiskyi - Lobes of the peripheral cells in one plane. __-_____ 6 . Lobes of the peripheral cells elongate and tipped by. a elobuilar swellinge ss. 21 235 r cet Ts P. glanduliferum . Lobes of the peripheral cells without apical thickenings 7 . Colony entire, without perforations, or with but Date W aint Uite oI CErshiGeS = a) cots et we or eA ee Ey th 8 euColony (Gistilictly,nertonate eset se. fe ge 12: . Incision of the peripheral cells deep and narrow sometimes linear and completely closed Seat ee 9 . Incision of the peripheral cells widely open __-_____-__________ 10 . Incision of the peripheral cells forming a closed sinus with the sides nearly parallel, peripheral cells definitely 4-lobed______ P. obtusum . Incision of the peripheral cells forming a sinus with converging margins, outwardly widely open; peripheral cells Hotpronunently 4A-loped = 1 ees er ss Vee SPE 9 ts P. tetras wiGelliwall-smoothor granulate: 42.002... 6. oc cleceecsk P. Boryanum pecelwallreticulate: 2. eet, rey Oe cee ee Uk A ie, oy 11 . Cell wall with fine, close reticulations; processes ofeperipheral cellon girs. .< oert See ee eee et P. sculptatum . Cell wall with coarse reticulations; processes of peripheral cells short, or with a broad concave emargination between them __ P. araneosum . Lobes of the peripheral cells bifurcate at their apices ____. P. biradiatum . Lobes of the peripheral cells not bifurcate at their apices ___ P. duplex Pediastrum araneosum (Racib.) G. M. Smith 1916, p. 476 [P. angulosum var. araneosum Raciborskil] Pl. 47, Fig. 4 Colony entire, or with minute interstices; cells 5-sided; peripheral cells 2-lobed; margin concave between the lobes, which are short and are about as far apart as are the lobes of two adjacent cells; wall with reticulate ridges; cells 15-32 in diameter. Common in the tychoplankton and euplankton of many lakes; generally distributed. Mich., Wis. [ 221 ] Pediastrum araneosum var. rugulosum (G. S. West) G. M. Smith 1916, p. 476 [P. Boryanum var. rugulosum G. S. West] Pl. 47, Fig. 3 A variety differing from the typical in having the adjoined cells distinctly undulated or crinkly. Euplanktonic and tychoplanktonic. Mich., Wis. Pediastrum biradiatum Meyen 1829, p. 773 Pl. 47, Figs. 5, 6 Colony perforate, the peripheral cells deeply bilobed, the lobes incised; cells adjoined along the lower part of their lateral walls; inner cells bilobed, the lobes not incised, all walls concave; diameter of cells 10—20z. Common in the plankton of many lakes; generally distributed. Mich., Wis. Pediastrum biradiatum var. emarginatum fa. convexum Prescott 1944, p. 356 Pl. 47, Figs. 7, 8 Colony perforate (clathrate), cells bilobed at the periphery, the lobes bifurcate, the inner margin of the lobules convex; peripheral cells adjoined along the lower part of their lateral margins only; lobes of inner cells merely emarginate; cells up to 11.7» in diameter, 9.7-10p long; 16-celled colony 44-50, wide. Rare, in Sphagnum bogs. Wis. Pediastrum Boryanum (Turp.) Meneghini 1840, p. 210 Pl. 47, Fig.9; Pl. 48, Figs. 1,3 Colony entire; cells 5—6-sided with smooth or granular walls; peripheral cells with outer margins extended into 2 blunt-tipped processes; cells up to 14 in diameter, 21u long; 36-celled colony 85—90u wide. Common in the eu- and tychoplankton of many lakes and swamps; generally distributed. Mich., Wis. Pediastrum Boryanum var. longicorne Raciborski 1889, p. 18 Pl. 47, Fig. 10 Peripheral cells with outer margins extended into longer processes than in the typical plant; apices of lobes swollen; cells 20-35-(40) » in diameter. Euplankter. Mich., Wis. Pediastrum Boryanum var. undulatum Wille 1879, p- 28 Pl. 48, Fig. 2 Similar to the typical plant, but the adjoining cell walls are undulate and irregular rather than straight; surface walls with granules or smooth; the lobes of the peripheral cells narrow and longer than in var. rugulosum, lobes of one cell about the same distance apart as are the lobes of adjoining cells; cells 17—22 in diameter. Euplankter. Mich., Wis. Pediastrum Braunii Wartmann in Wartmann & Schenk 1862, Fasc. 1, No. 32 Pl. 48, Fig. 5 Colony circular in outline, nearly entire but with a few interstices, composed of 4-16 quadrate or 5-sided cells (11 peripheral and 5 central); peripheral cells with 3 or 4 short, sharp projections which are unevenly spaced; interior cells 4-5-sided, the walls without projections or incisions; cells 9-12, in diameter. Euplankter. Wis. Pediastrum duplex Meyen 1829, p:. 772 Pl. 48, Fig. 4 Colony 8-128-celled, the walls smooth, with lens-shaped spaces between the inner cells, which are quadrate, the outer margin concave; peripheral cells quadrate, the outer margin extended into 2 tapering, blunt-tipped processes, distance between processes of one cell about one-half the distance between processes of adjacent cells; cells 15.6. in diameter; 36-celled colony 105 in diameter. Common in the eu- and tychoplankton of many lakes and swamps. Mich., Wis. Pediastrum duplex var. brachylobum A. Braun 1855, p. 93 A variety in which the peripheral cells bear 2 widely separated, very short, truncate processes (about 3 long); colony composed of 16-128 cells, with granular walls; colony up to 300, cells up to 40u, in diameter. Mich. Pediastrum duplex var. clathratum (A. Braun) Lagerheim 1882, p. 56 Pl. 48, Fig. 6 Colony with larger perforations than in the typical form; walls with deep emarginations; apices of lobes of peripheral cells truncate; cells 12-20 in diameter. Very common in a large number of lakes of both hard and soft water; generally distributed. Mich., Wis. [ 223 ] Pediastrum duplex var. cohaerens Bohlin 1897, p. 31 Pl. 48, Fig. 11 Colony with large clathrations; cell walls granular; cells 15-20. in diameter. Common in tychoplankton. Mich., Wis. Pediastrum duplex var. gracilimum West & West 1895a, p. 52 Pl. 48, Fig. 12 Colony with large perforations; body of cells narrow, equal in width to the processes of the peripheral cells, which are relatively larger than described for the typical plant. This is undoubtedly a growth form of the typical plant. Euplankter. Mich., Wis. Pediastrum duplex var. reticulatum Lagerheim 1882, p. 56 Pl. 49, Fig. 1 Outer margins of the peripheral cells having lobes with subparallel sides; inner cells nearly H-shaped. This form, like the preceding one, should be interpreted as a growth form of P. duplex. Widely distributed; euplanktonic. Mich., Wis. Pediastrum duplex var. rotundatum Lucks 1907, p. 31 Pl. 48, Fig. 8 Marginal cells with stout lobes which have convex rather than parallel margins; apices of lobes closer together than in the typical plant. Euplankter; common. Mich., Wis. Pediastrum duplex var. rugulosum Raciborski 1889, p. 24 Pl. 49, Fig. 3 Colony ovoid, entire except for small lens-shaped openings be- tween peripheral and inner cells; walls irregularly crenate and wrinkled, granular; cells 15-22, in diameter. Euplankter. Wis. Pediastrum glanduliferum Bennett 1892, p. 7 Pl. 49, Fig. 4 Colony elliptical, entire or nearly so; peripheral cells 5- or 6-angled with a concave incision between 2 long, capitate projections which are tipped with a globular swelling; cells about 10, in diameter, 12 long. Euplankter. Wis. [ 224 ] Pediastrum integrum N aegeli 1849, p. 97 PI. 48, Figs. 9, 10 Colony entire; cells 5-sided; outer margin of peripheral cells smooth or with 2 short and much reduced processes, and granular walls, emarginate between the processes; cells 16-25u in diameter. A smooth-walled form of this species, fa. glabra Racib., is fre- quently encountered. Euplankter. Mich., Wis. Pediastrum integrum var. priva Printz 1914, p. 73 Pl. 48, Fig. 7 Colony smaller than the typical plant; peripheral cells trapezoidal, the outer margins straight or slightly retuse. Euplankter. Wis. Pediastrum integrum var. scutum Raciborski 1889, p-5 Pl. 49, Fig. 2 Colony entire, 8—64-celled, walls thick; interior cells 5- or 6-sided; peripheral cells 5-sided, rhomboidal, the outer wall convex and without processes, surface of walls and free outer margins furnished with numerous, sharp granules; cells 10-18.5-(28), in diameter. Rare, in littoral flora. Mich., Wis. Pediastrum Kawraiskyi Schmidle 1897, p. 269 Pl.50, Fig. 1 Colony entire; inner cells 4- or 6-sided; peripheral cells napiform in vertical view, the outer margin extended into 2 projections which are not in the same plane, one usually directly above the other; cells 10-20, in diameter. Eu- and tychoplanktonic; common. Mich., Wis. Pediastrum muticum Kuetzing 1849, p. 193 Pl. 49, Fig. 8 Colony perforate, with 8-64 smooth-walled cells; inner cells 5- or 6-sided; peripheral cells with emarginate outer walls and 2 broadly rounded lobes, which are further apart than the lobes of adjacent cells; cells 20 in diameter. The original description of this plant contains no justification for including it with P. tetras as in DeToni, 1889, Sylloge Algarum, 1 (1) p. 581. Rare, in euplankton. Mich., Wis. [ 225 ] Pediastrum muticum var. crenulatum Prescott 1944, p. 356 PI]. 49, Fig. 9 A variety differing from the typical in having crenulate or ir- regularly wavy walls on both the adjoining and the outer free surfaces; colony large, as many as 134 cells (in concentric rows of 34, 31, 27, 21, 15, 6); cells 18-24.5y in diameter, colony up to 167p wide; 340, long. Rare; in plankton. Wis. Pediastrum obtusum Lucks 1907 (reprint), p. 13 [Pediastrum quadricornutum Prescott 1944, p. 3561 Pl. 49, Figs. 6, 7 Colony nearly entire, with minute interstices formed by the retuse margins of some cells; colony oblong, rarely subcircular (the rows of cells arranged: 7 - 1; 16- 11-5; 16-9-7), composed of from 8-32 cells which have a deep narrow sinus forming 2 major lobes, the lobes incised to form bluntly rounded lobules, the two central lobules in contact or nearly so, thus closing the sinus outwardly, the two lateral lobules in contact with the lateral lobules of the adjoining cells; interior cells about the same shape as the peripheral cells but with the lobules less prominent, sometimes wanting, with the wall merely emarginate or nearly straight; cells 10.5-18, in diameter; 8-celled colony up to 144» wide. Euplankter. Wis. According to Bigeard (1935) such a form as this would be included with P. tetras, a species which has many variations. Pediastrum obtusum is here regarded as separable from P. tetras on the basis of the narrow, closed incisions of the cells and the obtuse apices. The form was described by Prescott (1944) as P. quadricornutum because it seemed to be separable from the forms included in Bigeard’s monograph (1935). It had been described earlier, how- ever, as P. obtusum by Lucks (1907). Pediastrum sculptatum G. M. Smith 1916, p. 475 Pl. 49, Fig. 5 Colony entire or with narrow perforations; internal cells 4—6-sided; peripheral cells with 2 lobes having subparallel margins; cell wall covered with a fine reticulum of ridges; cells 10-15 in diameter; colony 150-180, wide. Euplankter. Wis. [ 226 ] Pediastrum simplex (Meyen) Lemmermann 1897, p. 180 Pl. 50, Fig. 2 Colony entire, composed of 16-32-64 smooth-walled cells; inner cells 5- or 6-sided; peripheral cells with the outer free wall extended to form a single tapering, horn-like process with concave margins; cells 12-18y in diameter. Common in the plankton of a number of lakes. Mich., Wis. Pediastrum simplex var. duodenarium ( Bailey ) Rabenhorst 1868, p. 72 Pl. 50, Figs. 4, 5 Colony perforate, composed of 36-48-64 cells with their inner margins concave, the outer margin of inner cells forming a long pro- cess, peripheral cells forming a stout process; cells 11-15y in dia- meter, 27-28 long; 36-celled colony 137, in diameter. Euplankter. Mich., Wis. Pediastrum tetras (Ehrenb.) Ralfs 1844, p. 469 Pl. 50, Figs. 3, 6 Colony entire; inner cells (frequently none) with 4-6 straight sides but with one margin deeply incised; peripheral cells crenate, with a deep incision in the outer free margin, their lateral margins adjoined along 2 of their length; cells 8-12-(16) in diameter. Common and generally distributed in both eu- and tychoplankton. Mich., Wis. Pediastrum tetras var. obtusata Raciborski 1889, p. 32 Cells larger than in the typical plant, the outer margin of the peri- pheral cells straight, not so emarginate; cells 14-18, in diameter, 18-22, long. Euplankter. Wis. Pediastrum tetras var. tetraodon (Corda) Rabenhorst 1868, p. 78 Pl. 50, Fig.7 Colony 4—8-celled, outer margins of peripheral cells with deep incisions; the lobes extended into sharp, horn-like processes; cells 12-15, in diameter, 16-18, long. Euplankter. Mich., Wis. SORASTRUM Kuetzing 1845, p. 144 A spherical colony of either loosely or compactly arranged reni- form, pyriform, cuneate or pyramidate cells, attached by radiating strands to a common polyhedroid central body of mucilage; outer [ 227 ] and free surface of the cell furnished with 1-4 stout, outwardly directed spines; 1 diffuse chloroplast covering most of the wall, containing a single pyrenoid. Key to the Species Cells broadly cuneate; spines 4—8u long —__._.._--_--_----- S. spinulosum Cells narrowly cuneate; spines 10—15u long. S. americanum Sorastrum americanum (Bohlin) Schmidle 1900d, p. 230 Pl. 50, Fig. 8 A free-floating spherical colony of 16-128 heart-shaped or sub- pyramidate cells with the outer free walls emarginate and furnished at each of the 4 angles with a long, stout, outwardly directed spine; cells narrowed toward the base and attached to the center of the colony by a short, cylindrical stalk which at the base is 5- or 6-sided adjoining the sides of other stalks in such a way as to form a central hollow sphere; cells 7-20» in diameter, 5-20 long, 4-8 thick; spines 10-15». long. Rare; in several soft water lakes, especially in northern counties; eu- and tychoplanktonic. Mich., Wis. Sorastrum americanum var. undulatum G. M. Smith 1918, p. 640 Pl. 50, Fig. 10 A variety differing from the typical in having the margins of the facets at the base of the stipe undulate. Rare; in the euplankton of lakes. Wis. Sorastrum spinulosum Naegeli 1849, p. 99 PI. 50, Fig.9; Pl. 53, Fig.1 A spherical, free-floating colony of 4-32 rhomboidal, reniform, or broadly cuneate cells attached by a very short and broad stipe to a common center; outer free wall straight, furnished at each angle with 2 relatively short spines, 4-8 long; cells 8-20, in diameter, 6-18, long, 5—8p thick.. Common in the plankton of many lakes; generally distributed. Mich., Wis. . FAMILY COELASTRACEAE This small family is characterized by cells that are radiately arranged and adjoined, forming globular colonies which may be either hollow or solid. In most species the cells are interconnected by narrow processes or by extensions of the cell membrane to form interstices. The chloroplast is parietal, covering nearly the entire wall. Reproduction is by formation of a definite number of auto- [ 228 ] spores within each cell of the colony. These become adjoined to form daughter colonies before being liberated. There is but one genus, Coelastrum, since “Phytomorula”? has been found not to be an alga. COELASTRUM Naegeli in Kuetzing 1849, p. 195 A hollow, spherical, free-floating colony of as many as 128 globose, ovoid, or pyramidal cells which either are closely adjoined and compressed, or interconnected by narrow processes to form a fenestration. Daughter colonies are formed within the parent cells; the walls of the parent cells may persist about the new colonies, interconnecting them and so forming complexes. Key to the Species 1. Cells without arms; interconnecting processes extremely short, sometimes: scarcely ‘evident! 2 1. Cells with arms, or with longer and very evident IntercOMNE CHINE MTOCESSES = 95 = oh 4 2.) Cell walls with-wart-like processes. = C. scabrum 2. Cell: walls’ without ‘wart-like processes =) ==). 3 8. Cells spherical or ellipsoidal, closely adjoined, with interstices narrower than the diameter of the cells_......___-__»_»_»_»»__ C. microporum 3. Cells conical, adjoined, but with interstices as wide as the Gdiameter of the cells, or wider... es C. sphaericum 4. Cells pyramidal or conical; arms truncate, adjoined within the colony in such a way as to form large fenestrations... C. proboscideum Are G@ellsesplericnll» 8.7 k ait. EE an Se ot tate Dn Ee 5 5. Cells at the ends of long gelatinous strands fainting irom asconmion. center. (te 122 2 sie Se Se ed C. speciosum o. Gells\not at the. ends of long radiating strands 6 6. Outer free walls of the cells with a truncate projection; interconnecting processes of cells short._.._-.....--------------------- C. cambricum 6. Outer free walls of cells without a projection; mterconmecting processes long. 2 st C. reticulatum Coelastrum cambricum Archer 1868, p. 65 Pl. 58, Fig. 2 Coenobium spherical, usually composed of 32 globose cells (rang- ing from 8 to 128 in number), each cell adjoined to neighboring cells by 6 broad, short projections of the sheath so that triangular intercellular spaces result; outer free wall of the cells with a flattened, truncate projection; cells 10-20. in diameter, including sheath. Widely distributed and common in the plankton of a great variety of lakes and bogs. Mich., Wis. 3Phytomorula regularis Kofoid, the only species described, has been shown to be pollen of Acacia spp. (H. F. Copeland in Madrofio, 4, pp. 120-125. 1937); hence the family Coelas- traceae is monogeneric, unless Chodat’s genus Coelastrella should prove to be well founded. [ 229 } Coelastrum microporum Naegeli in A. Braun 1855, p. 70 PI. 53, Fig. 3 Coenobium spherical, composed of 8-64 sheathed globose cells (sometimes ovoid, with the narrow end outwardly directed); cells mterconnected by very short, scarcely discernible gelatinous proc- esses, leaving small intercellular spaces; cells 8-20. in diameter including the sheath. Common in the tychoplankton of many lakes and ponds. Mich., Wis. Coelastrum proboscideum Bohlin 1897, p. 33 [C. compositum G. S. West] Pl. 53, Figs. 4, 5, 8 Coenobium pyramidal or cubical (rarely polygonal), composed of 48-16-32 truncate cone-shaped cells with the apex of the cone directed outward, the inner or basal wall of the cell concave, the lower lateral walls of the cells adjoined about a large space in the center of the colony; cells 8-15, in diameter; 4-celled colony as much as 35p in diameter. In both tycho- and euplankton of several lakes; not as common as other species of Coelastrum. Mich., Wis. Coelastrum reticulatum ( Dang.) Senn 1899, p. 66 Pl. 53, Fig. 6 Coenobium spherical, free-floating, composed of 8-32 globose cells each inclosed by a gelatinous sheath and adjoined to neighboring cells by 6 long, slender gelatinous processes, leaving large intercell- ular spaces; outer free wall of the cells without protuberances or processes; cells 8—20-(24) » in diameter including the sheath. Euplankter. Mich., Wis. Coelastrum scabrum Reinsch 1878, p. 238 Pl. 46, Fig. 3 Coenobium spherical, composed of 8-16 angular-globose to angular-depressed-globose cells which bear on their outer faces 4-6 short, wart-like and truncate projections; cells 8-10 in diameter. Mackinaw City, Michigan. Coelastrum speciosum (Wolle) Brunnthaler 1915, p. 197 Coenobium spherical, composed of 16-24 spherical cells, each at the end of a slender gelatinous strand radiating from the center of the colony; outer face of the cell with a single, short-truncate gel- atinous projection; cells 10-12» in diameter. Cheboygan County, Michigan. [ 230 ] Coelastrum sphaericum Naegeli 1849, p. 98 Pl. 53, Fig. 7 Coenobium ovoid, composed of conical cells, the narrow end directed outward, adjoined without processes along the lower lateral walls, forming interstices which are equal to or greater than the diameter of the cells; cells up to 25, in diameter. Euplankter. Mich., Wis. FAMILY BOTRYOCOCCACEAE This family is composed of plants which have ovoid or spherical cells embedded and crowded in tough, often foamy, irregularly shaped masses of mucilage which are frequently darkly colored and semi-opaque. In some species the cells are inclosed in a cup of fatty substance with an outer layer of pectic material. The chloroplast is an open or close parietal net-work, usually with 1 pyrenoid. Both starch and oil accumulate as food reserve, the latter often so dense as to obscure the true nature of the cell content. Asexual reproduc- tion is carried on by autospores. As here defined, this family includes only the genus Botryococcus which has been given various taxonomic positions. Because the fatty material] in which the cells are embedded is so darkly colored in the type species, B. Braunii Kuetz., the exact nature of the cell content and pigmentation has been difficult to determine. Until recently the genus has been placed in the Heterokontae (Chrysophyta) with a few other genera, to comprise the family Botryococcaceae. The critical studies of Blackburn (1936) on Botryococcus Braunii Kuetz., however, seem to establish the identity of this species as a member of the Chlorophyta. The morphology of the wall, the presence of a pyrenoid and of starch, and the habit of retaining mother cell membranes and secretions in the building of the colony justify the removal of the genus from the Chrysophyta. Blackburn (l.c.) rightly proposes that the Botryococcaceae be placed near the Dictyo- sphaeraceae. See page 237. BOTRYOCOCCUS Kuetzing 1849, p. 892 [Ineffigiatus West & West] Thallus an irregularly globose or bullate colony of ovoid or spherical cells densely arranged somewhat radially in a sticky, often dark-colored mucilage, the cells embedded in a cup-like sheath of fatty material in one species; compound or net-like aggregates of colonies may be formed by long or short strands of rubbery mucilage connecting several clusters of cells; chloroplast a fine or close [ 231 ] net-work covering only part of the wall, containing 1 pyrenoid; both starch and oil present as food reserves; reproduction by frag- mentation and by autospores. Key to the Species 1. Cells inclosed by a tough, rubbery, often darkly colored mucilage ._-______. 2 1. Cells invested by a thin, colorless mucilage == B. sudeticus 2. Colonial envelope completely covering the cells; mucilage darkly colored, especially in the older colonies... B. Braunii 2. Colonial envelope leaving the outer face of the cells free B. protuberans Botryococcus Braunii Kuetzing 1849, p. 892 Plo, wigsa le. Ut Cells ellipsoid, radiately arranged at the periphery of irregularly shaped, usually dark-colored masses of mucilage; free floating; colonial mucilage much folded and extended into tough, foamy strands, often forming colonial complexes by interconnecting strands of mucilage; chloroplast a thin, or dense, parietal net with 1 pyrenoid, covering only a portion of the wall (often masked by the dark color of the mucilage); starch and oil droplets present; individual cells invested by a layer of fatty substance and an outer layer of pectin; cells 3-6 in diameter, 6-12, long. Common, and often abundant, especially in semi-hard water lakes where it frequently is the dominant component of water-bloom associations. Mich., Wis. Botryococcus protuberans var. minor G. M. Smith 1918, p. 652 Pl. 52, Figs. 4,5 Cells ovoid, arranged in few-celled clusters which are connected by long tough, fibrous strands, 4-16 such clusters involved to form multiple colonies; cells embedded in but not entirely surrounded by mucilage, one end protruding at the periphery; cells 5-6.5 in diameter, 8—9.5, long. Rare to common in the euplankton of several lakes, Mich., Wis. Botryococcus sudeticus Lemmermann 1896a, p. 111 Pl. 52, Fig. 3 Cells spherical, clustered and embedded in a hyaline mucilaginous envelope, forming irregularly shaped or somewhat spherical masses which may be joined together by gelatinous strands to form com- plexes; cells 6-13, in diameter. Rare in the euplankton of several lakes. Mich., Wis. [ 232 ] FAMILY OOCYSTACEAE This is a large family in which there is a wide range in cell shape and arrangement. The cells may be spherical, ovate, pyramidal, or polygonal. Some forms are unicellular, others colonial. The chief characteristic which unites the 30 or more genera is the autospore method of reproduction; ordinary cell division and zoospore for- mation are not known. The autospores are small replicas of the mother cell and are usually cut out in a definite number from the parent protoplast. Upon escape they may remain together to form a colony, as in the Coelastraceae, or may separate. Unlike the Coelastraceae and the Scenedesmaceae, however, the colonies are not composed of definitely arranged cells. In most cases the cells are not adjoined but are held together by a gelatinous investment or by the enlarged and persistent mother cell wall, or gelatinized portions of the old wall. In the majority of forms there is a single, laminate chloroplast, but a few species have several to many disc- like bodies, each with a pyrenoid. Multinucleate cells are rare. Key to the Genera 1. Plants endozoic in the cell or body cavities of animals RS OME CS UTR: TELCO) ian ahs ce tte! Seen wn Se ee ee Zoochlorella Tarts mots CUE OAOTC se. wre aed LN ee A oe eee Se 2 Opel lear tssesuiray ce ll eit sa 92 a Fa en eg ne a 3 ems ATUESHS COOMA Noe Wee eke eee BI Re le Ly epee 21 8. Cells angular, pyramidal, triangular, or polygonal ____________________ 4 3:, Gells: spherical, ellipsoid, ovoid; or acicular— 8 Ae angies bearings spines ‘Or bristles. ee 6 4, Angles not bearing spines; smooth or with the angles produced and extended to form simple or branched processes___...._._------_----------------- 5 5. Cell body evident, distinguishable from the extensions of the angles, or with angles smooth and rounded. Tetraédron (part) 5. Cell body not clearly evident, gradually extended into the processes of the sanglesz 2 S30. et Cerasterias ( part ) 6. Body of the cell evident, with or without POC eG eet le seeteemetien eres eats eR ee 32 6. Body of the cell not clearly evident, gradually extended into the processes . 7 7. Angles of the cell with a thick, stout, and very long spine Treubaria 7. Angles of the cells gradually narrowed to form a spine-like tip, or with the apices tipped with minute spines___________ Cerasterias (part) Gas Cells splierice late ene eet ere eee eee ee eee Se ee 9 SeCellssovate:. ellipsoids lunate, “or GicicMlar =)... scan fescacesnoeeteeeadnedeeoneene 14 9. Cell wall ric LGROMUROMDME Ns ou ay a re) 10 SeGeulwallenot asin Ot eee weer eae ant aoe ties ee ee eae Hts} 10. Cells with 1 chloroplast (see also Zoochlorella) Chlorella 10 Cells; with several tosmany chloroplasts 4° 5 Te 11. Cells inclosed by a wide gelatinous investment; chloroplasts not » in a reticulum nor in radiating strands. Planktosphaeria (part) 11. Cells not inclosed by a gelatinous investment —_________._______-_-_------- 12 [ 233 ] 12. Chloroplasts numerous irregular plates arranged in a reticulum or in strands of cytoplasm radiating from the center of the cell; pi ofall Wo of 5 « Mane aan UL Ee eek OI AN BAC Zs Ney Dee LI oe A Eremosphaera 12. Chloroplasts cone-shaped, arranged at the periphery and projecting inward; wall thick and lamellate_________ Excentrosphaera 13. Cell wall with reticular markings or with short spines _.. Trochiscia 13. Cell wall with several long, sometimes stout, spines Echinosphaerella Tas @ells ellipsoid oan Ee ee ee eee 15 14, Cells lunate, straight and fusiform, or acicular____-__________________ 17 Tb>aGells: without spinesor setae. Oocystis ( part ) 15.) \Cells\ bearing spines) Or/setae 2-2 id ae 16 16. Setae distributed over the entire cell wall —_______-__------------------- Franceia 16. Setae arising from the poles only, or from the poles and the equator ei BAe 2k 2 Re ee Ee ee Lagerheimia Lie Gellsilunate distinctly jemrved See ts et Ea Yee ee eee 18 L7aeellststraignt, acieular,iorjfusitorm sme uale2 TE eee eee 19 18. Cells invested by a gelatinous sheath________________-_-- Kirchneriella (part) 1$2' Cells notjinclosedbyya) sheath 4 ee Ankistrodesmus ( part ) 19. With a fine, needle-like spine at one or both poles of the cell Schroederia 19. Poles of the cell without a spine, although apices may taper toy aslinte pointasiee fs oe hei ate ee ee eee 20 20. Chloroplast an elongate plate with a row of pyrenoids; cell up to 5304 long reece aa ect Bs MOURNE ee Meron er eds Closteriopsis 20. Chloroplast without pyrenoids, or with but 1; cell’ much shorter than above... Ankistrodesmus ( part ) Die Cellsiwithia celatmousiinvestment = = se eee 22 2ieiGellsiwithoutkagelatinousinvestment =" eae se 26 22 Cellsisphenicaly or broad lyiovatetiene es ee wee 23 22. Cells not spherical, but elongate, at least twice as long as wide —...__ 24 23. Cells arranged in clusters at the ends of radiating strands _Dictyosphacrium 23. Cells not adjoined by radiating strands Planktosphaeria ( part ) 24. Cells straight, with long axes parallel in the colony___-- Quadrigula AM Ge SS Currey CC eee ae re ee Oe ee ee 25 25. Cells invested by a firm sheath (gelatinized mother cell wall); cells’ slightly, curved: or remiform 2. -.o..cecccsee oapcese cote peers Nephrocytium 25. Cells in a homogeneous, thin mucilage; sharply curved, lunate or sickle-shaped.......................:-:0-00- Kirchneriella (part) 26. Cells adjoined by remains of old mother cell walls at-the center of the: colomy:..0 72 Ues J. 1.26 2) ee ee oT 26. Cells held together by other means; fragments of old mother cell wallsinot presentat centerol colony. = ee 28 27. Cells spherical; cell wall fragments curved and unbranched... Westella 27. Cells reniform or ovoid; cell wall fragments forming straight branching) strands. ee Dimorphococcus 28. Cells spindle-shaped; adjoined end to end to form ALChain which miay Drala cli: sass ine Loewe eee eee Dactylococcus 28. Cells not spindle-shaped and not adjoined end to end dint alcchrain® like wS ee GS ie oes nie a eI Ce 29 29. Cells ovate or spherical, inclosed by enlarged mother cell walls___________-- 80 29. Cells elongate, acicular, or spindle-shaped__________-__-------------------------------— 31 30. Cells separated from one another by a deposit of semi-opaque mucilage which forms cruciately arranged bands about, thie ;Colonyst.5 odode, Sen ee ee ee eee Gloeotaenium 30. Cells not separated by semi-opaque deposits of mucilage_. Oocystis (part) 31. Cells lunate or sickle-shaped, with their convex SUEEACES AP DOSeCi. ees oc ene et Sl oo! Selenastrum 31. Cells straight, in fascicles or irregular clusters, sometimes twistedabout one. another t=. “Ue Ne eee Ankistrodesmus (part) 32. Angles tipped with 4-6 fine, hair-like bristles 3 Polyedriopsis 32. Angles tipped with 1, 2, or 3 short, stout spines ___ Tetraédron (part) ZOOCHLORELLA Brandt 1882, p. 140 Unicellular; spherical or ovoid; inhabiting the cells and body cav- ities of animals. Chloroplast (sometimes 2) a parietal plate covering only a portion of the wall; pyrenoid usually present. Reproduction by aplanospores, as in Chlorella. This group, with justification, is regarded by some students as being congeneric with Chlorella. It is arbitrarily separated here and the name retained in order to provide a distinct category for the endozoic species. The phenomenon of ‘green’ animals, such as Hydra, Ophrydium, Spongilla, etc., is invariably referred to as being caused by Zoochlorella. Long usage, therefore, seems to warrant the sepa- ration. The relationship between species of this group and various animals is apparently definite and not haphazard. The symbiosis may vary from commensalism to parasitism. Although the species are described as having no pyrenoid, our specimens usually showed this body very clearly, especially in larger cells. Key to the Species Plants inhabiting Hydra; cells 3-6u in diameter Z. conductrix Plants inhabiting Ophrydium, Spongilla, and Stentor; @ellsnltn—s ein Ciaimeter ee oe te Pai ee! Z. parasitica Zoochlorella conductrix Brandt 1882, p. 140 Pl. 53, Fig. 10 Cells globose or broadly ovoid, usually densely compacted with the cells of Hydra; chloroplasts 1-2, usually with a pyrenoid; cells 3-6, in diameter. Common; in green Hydra; inhabiting ponds and swamps where there are dense beds of aquatic vegetation. Mich., Wis. Zoochlorella parasitica Brandt 1882, p. 140 Pl. 53, Fig. 9 Cells ovoid, inhabiting Ophrydium, fresh-water sponges (Spong- illa), and Stentor spp.; chloroplast 1 (rarely 2); cells 1.5-3» in diameter. Common in Ophrydium, a colonial ciliate which forms floating or attached gelatinous masses 1-10 cm. in diameter. Sometimes the [ 235 ] colonials are attached to submerged vegetation. The algal cells vary in abundance so that the colony may be light or very dark accord- ingly. The protozoan inhabits mostly hard water lakes where it is frequently mistaken for Nostoc, Tetraspora, or some other gelatinous alga. Mich., Wis. CHLORELLA Beyerinck 1890, p. 758 Unicellular, solitary or aggregated in irregular clumps; round or ellipsoid; variable in size in the same habitat. Chloroplast a parietal cup or merely a plate, with or without a pyrenoid. Reproduction by 4 or 8 daughter cells (non-motile) produced from the protoplast of the mother cell. This small plant may be confused with species of Chlorococcum, a soil or subaerial genus, from which it can be differentiated with surety by a study of reproductive habits. It is very similar also to many other unicellular green algae and may be confused with motionless ZOOspores of some genera. It is necessary, therefore, to study a large number of individuals, or better still to culture the plants in making identification. Chlorella forms 4 or 8 daughter cells within the mother cell wall whereas Chlorococcum produces biflagellate zoospores which escape and immediately separate from one another. In Chlorococcum the chloroplast more nearly covers the cell wall than in Chlorella. Chlorococcum lives almost entirely on or in soil, sometimes at con- siderable depth, or on old wood and rocks. Chlorella is aquatic but may share the same habitat with Chlorococcum. Beyerinck (1890) recommends combining Chlorella and Zoo- chlorella, but for the reason mentioned above (under Zoochlorella ), they are separated here. Key to the Species Cells ellipsoidal, 7-8 in diameter, 9.5 long: Mesias C. ellipsoidea Cells spherical, usually 5-10 in GaaMeter eet tS es ee C. vulgaris Chlorella ellipsoidea Gerneck 1907, p. 250 Pl. 58, Figs. 11, 12 Cells ellipsoidal, sometimes unsymmetrical; chloroplast a folded plate over part of the cell wall; described as producing as many as 32 autospores during reproduction; vegetative cells 7-8, in diameter, 9-9.5p long. Generally distributed in many lakes and ponds. Mich., Wis. [ 236 ] Chlorella vulgaris Beyerinck 1890, p. 758 PI. 53, Fig. 13 Cells spherical, scattered among other algae or sometimes occur- ring in almost pure growths; chloroplast a parietal cup, sometimes without a pyrenoid; cells 5-8.5-(10) in diameter. In small lakes and pools, especially where there is a concentration of organic matter. Mich., Wis WESTELLA de Wildemann 1897, p. 532 A free-floating, globose colony of 30-100 spherical cells without a gelatinous investment; members in groups of 4 and bound together by the persistent remains of old mother cell walls; 1 parietal, cup- shaped chloroplast, often with a pyrenoid. Key to the Species Colonies of 40 cells or fewer; cells arranged in linearseries;)6=G.in diameter: 2b he W. linearis Colonies of 40-80 cells; cells arranged to form quadrate Or pyramidate clusters 2 8 W. botryoides Westella botryoides (W. West) de Wildemann 1897, p. 532 PI. 58, Fig. 14 Colony composed of 40-80 spherical cells, quadrately arranged in groups of 4, the groups loosely connected by the persistent remains of old mother cell walls; cells with 1 parietal, cup-shaped chloroplast; pyrenoid sometimes present; cells 3-9, in diameter. Rare but widely distributed, in a large number of lakes, especially in the plankton of soft water. Mich., Wis. Westella botryoides var. major G. M. Smith 1918, p. 628 A variety differing from the typical by having larger cells, 8-13p in diameter. Rare in euplankton. Mich., Wis. Westella linearis G. M. Smith 1920, p: 107 Pl. 53, Figs. 15, 16 An irregularly shaped colony of about 40 spherical cells arranged in a linear series of 4; groups of cells held together by inconspicuous remains of old mother cell wall fragments; cells 3-6. in diameter. Rare in euplankton. Wis. DICTYOSPHAERIUM Naegeli 1849, p. 72 Colony globular or ovoid, composed of spherical or ovoid cells attached by fine, branching strands which radiate from a common [ 237 ] center, the entire colony invested by a wide, hyaline, gelatinous envelope; cells with 1 or 2 parietal chloroplasts, each with a pyrenoid. Key to the Species Cells ellipsoidal or ovoid; colony ovoid D. Ehrenbergianum Cellsispherical; colony usually globose! = ee D. pulchellum Dictyosphaerium Ehrenbergianum Naegeli 1849, p.73 Pl. 51, Figs. 3, 4 Colony ovoid, composed of 8-30 ellipsoidal cells with 1 or 2 parietal or cup-like chloroplasts, cells attached in groups of 2 or 4 at the ends of fine, branched strands; cells 4-6y in diameter, 8-10 long. Goenee in the plankton of many soft water lakes. Mich., Wis. Dictyosphaerium pulchellum Wood 1874, p. 84 PI. 51, Figs. 5-7 Colony spherical or ovoid, composed of as many as 32 spherical cells arranged in series of 4 on dichotomously branched threads, inclosed in mucilage; cells 3-10 in diameter. This species is sometimes a conspicuous component of the plankton in acid bog lakes. Taylor (1935) has found it in the leaves of pitcher plants (Sarracenia purpurea L. ) Generally distributed in many soft water as well as semi-hard water lakes. Mich., Wis. TROCHISCIA Kuetzing 1833b, p. 592 Free-floating (or sometimes subaerial), spherical, unicellular plants with thick walls which are either smooth or variously sculptured and decorated (reticulations, warts, spines); with 1 to several plate-like, parietal chloroplasts; pyrenoids 1 or more. Some care must be used in distinguishing members of this genus from the zygospores of some desmids. The latter have a single, massive chlorophyll-bearing body of indefinite form. Key to the Species 1. Wall decorated with granular, wart-like or spine-like roughenings — 2 1. Wall decorated with ridges which may be concentric and: parallel; or may, form ‘a xeticulun=— 8 6 eee 8 2. Granulations sharply pointed and numerous.._..-...--------------------- T. aspera 2. Granulations low and blunt, not so closely AETAN SEC 525) 5 AON Cet ea te oe an ae aT der T. granulata 3. Wall with concentric ridges which form low,bhunt: protuberances: 050 00 iio hawk Ee eee T. obtusa Suk Wall’ with reticulate ric ges: 5 be 5 8 ee eee 4 4. Reticulations coarse, forming ‘8-10 visible polygonal areas ____ T. Zachariasii 4. Reticulations fine, forming as many as 35 visible areas vonsthes wall. se dite) ais Ca onc) Bee, oa ae T. reticularis [ 238 ] Trochiscia aspera (Reinsch) Hansgirg 1888a, p. 128 PI. 53, Fig. 17 Cells free-floating, globose, the wall moderately thick, decorated with evenly distributed, wart-like projections (interconnected by faint lines P), chloroplasts several, disc-shaped; cells (13 )-18-29.5u in diameter. Rare in plankton. Mich., Wis. Trochiscia granulata (Reinsch) Hansgirg 1888a, p. 128 Pl. 53, Fig. 18 Cells aquatic or subaerial, spherical, the wall thick and densely covered with low, granular or wart-like roughenings; cells 10-20- (23) in diameter. In a Sphagnum bog. Mich., Wis. Trochiscia obtusa (Reinsch) Hansgirg 1888a, p. 130 PI. 52, Fig. 8 Cells spherical, the wall thick, with concentric series of ridges or low, parallel protuberances; 34-37, in diameter. Tychoplankter. Mich., Wis. Trochiscia reticularis (Reinsch) Hansgirg 1888a, p. 129 PI. 53, Figs. 19, 20 Cells free-floating, spherical, with thick walls which are externally ridged to form a reticulum in which as many as 70 polygonal areas may be marked out; cells up to 39, in diameter. This plant also passes under the name of T. sporoides (Reinsch) Hansgirg. Rare; in several lakes and Sphagnum bogs. Mich., Wis. Trochiscia Zachariasii Lesamermann 1903, p. 157 PI. 58, Fig. 21 Cells free-floating, spherical; wall very thick and decorated ex- ternally with a very coarse reticulum of prominent ridges marking out 8-10 irregularly shaped, polygonal areas on the visible side of the cell, forming prominent projections at the periphery; cells 10-20. in diameter. Rare, in plankton. Wis. PLANKTOSPHAERIA G. M. Smith 1918, p. 627 A free-floating colony of spherical cells compactly grouped within a mucilaginous, homogeneous envelope; chloroplasts several, angu- lar, parietal discs, each with a pyrenoid. [ 239 ] Planktosphaeria gelatinosa G. M. Smith 1918, p. 627 Pl. 53, Fig. 23 Characteristics as described for the genus; cells (4.5)—20-25, in diameter. This plant should be compared with Sphaerocystis Schroeteri, which has a single parietal, cup-shaped chloroplast and in which the cells are usually more distantly arranged. In old colonies of Planktosphaeria gelatinosa the cells may become somewhat loosely arranged, but usually they are closely clustered. Common in the plankton of a variety of lakes and ponds, both in hard and soft water. Mich., Wis. EREMOSPHAERA DeBary 1858, p. 56 Cells spherical, spheroidal, or somewhat angular-spheroidal (3- angled in face view); solitary or 2-4 together within an old mother cell wall, with or without a gelatinous sheath; free-floating or lying among mixtures of algae in shallow water; chloroplasts numerous, ovate or irregularly shaped discs or pads, with large starch grains, lying in a meshwork along the periphery or in radiating strands of cytoplasm from a central core which involves the nucleus. The chloroplasts are able to shift their position in response to light stimulus. Key to the Species Cells spheroidal or angular-spheroidal, 2-4 within an old mother cell wall, inclosed by a gelatinous sheath —_____-_______- E. oocystoides Cells spherical, solitary, sheaths not apparent.___________________-__ E. viridis Eremosphaera oocystoides Prescott in Prescott, Silva & Wade 1949, p. 85 Pl. 46, Fig. 12 Cells spheroidal or triangular-spheroidal in one view, 2-4 (rarely solitary) within old mother cell walls which are ovate or oblate- spheroidal, inclosed in a wide gelatinous sheath in which there are numerous radiating spicules, the old mother cell wall often appear- ing spiny, and showing flattened, thickened poles; chloroplasts numerous, small irregularly shaped plates, lumpy with starch grains; cells up to 122» in diameter; colony 300-450» in diameter. In shallow water of an acid swamp. Mich. Eremosphaera viridis DeBary 1858, p. 56 Pl. 53, Fig. 22 Cells solitary, spherical, not inclosed by a mucilaginous sheath; chloroplasts as described for the genus; cells 50-350, in diameter. [ 240 ] This plant is so definitely restricted to soft water habitats that it may be used as an index organism for acid conditions in which the pH is 6.0-6.8. It is a common component of a flora in which desmids predominate, and there is some evidence that high organic acid content of the water results in huge Eremosphaera cells. Common in many acid lakes and Sphagnum bog ponds. Mich., Wis. EXCENTROSPHAERA Moore 1901, p. 322 Cells spherical or ellipsoid, free-floating, intermingled with other algae, the wall thick and often lamellate; chloroplasts numerous cone-shaped bodies arranged at the periphery and directed inward, each with many small pyrenoids; reproduction by aplanospores. Excentrosphaera viridis Moore 1901, p. 322 Pl. 46, Figs. 15, 16 Characteristics as described for the genus; cells 22-55, in diam- eter; spores (not observed in our collections) 2-3, in diameter. Tychoplankter; in shallow water of lake margins and soft water or acid swamps. Mich. ECHINOSPHAERELLA G. M. Smith 1920, p. 128 Free-floating, globose cells, entirely covered with long, stout, tapering spines; chloroplast 1, cup-shaped and parietal, containing a single pyrenoid. The genus is monotypic. Echinosphaerella limnetica G. M. Smith 1920, p. 128 Pl.51, Figs. 1, 2 Characteristics as described for the genus; cells 9-12, in diameter exclusive of spines; spines 2.5-31 wide at the base, 20-25, long. This species should be compared with desmid zygospores, many of which have spiny walls and greatly resemble Echinosphacrella. Differentiation can be made on the basis of the chloroplast, there being no definitely shaped chlorophyll-bearing body in the desmid zygospore, but a dense, rather shapeless mass. Rare, in plankton. Wis. TREUBARIA Bernard 1908, p. 169 Free-floating, pyramidal or flattened 3- to 4-angled unicells, the angles rounded or produced to form a stout, thick-based spine which is either tapering or has subparallel sides; the margins of the cell concave between the angles; chloroplasts 1-4, parietal, [ 241 ] cup-shaped in some, becoming massive and filling the cell; 1 or more pyrenoids, usually 1 in each angle of the cell. This genus should be compared with the pyramidal species of Tetraédron, in which the angles of the cell are sometimes drawn out to form arms. Some species of Tetraédon have the angles bearing spines, but these are relatively short, never equaling the diameter of the cell, whereas in Treubaria the angles of the cell are spines, which are much longer than the diameter of the cell body. Treubaria setigerum (Archer) G. M. Smith 1933, p. 499 [Tetraédron trigonum var. setigerum ( Arch.) Lemmermann] Pl. 51, Fig. 8 Cells triangular and flattened in surface view, the angles broadly rounded and then produced to form a long tapering spine; chloro- plast a parietal plate, covering the cell wall; cells 7-9, in diameter; spines 12-15, long. Rare; in tychoplankton. Wis. OOCYSTIS Naegeli in A. Braun 1855, p. 94 Unicellular or in colonies of 2-16 individuals inclosed by the persistent and much swollen mother cell wall of the previous generation; several successive generations of cells sometimes in- closed within old membranes; cells ovoid, ovoid-ellipsoid, or rarely subcylindric, with rounded poles which may be smooth or furnished with a conspicuous nodule-like thickening; chloroplasts 1 or many, mostly parietal, of various shapes, ovoid discs, irregular star-shaped plates, or reticular; 1 pyrenoid in each chloroplast (sometimes wanting ). Key to the Species il Poles) vot) cells) wathe nodular. thickening) ce. cee ese ceseed reer eee 2 1. Poles of cells without nodular thickening; apices rounded or pointed... 9 2. Cells with one pole thickened, the other broadly rounded; cellsvisomew hate, pyri Orit ele ica. ttle Weel entoaeec snes ae O. pyriformis 2. Cells with nodular thickenings at both poles; Celismovals vellipHe Or gOOlom ee! write ee eet ate: toe erhe neaeaeen deer erase ea 3 3. Chloroplasts mumerous, 4—25—60 ooo... cece eeeent etre ttteteeen rere eres 4 3. Chloroplasts fewer in number, 1—3 (rarely 4) .........0:ccce ii 4. Cells oblong, with lateral walls concave; chloroplasts) M2 Dose. 4it s meedeont dy et aeetusteneett ieee zeceto scien O. panduriformis 4. Cells elliptic or oval (sometimes nearly round)...........0.0.:c::cc 5 5. Chloroplasts 40—60 irregularly lobed, parietal discs ...... O. Eremosphaeria 5. Chloroplasts fewer, disciform or oval, laminate ................... ce 6 6. Chloroplasts relatively large, 4-10; mother cell wall much swollen and inclosing 2—4—(8) daughter cells.................... O. crassa 6 . Cloroplasts smaller and more numerous, 12—25; mother cell wall not swollen; cells mostly solitary ae (uncommonly as many as 8 in’/a famiy).........00...0......c: O. solitaria [ 242 ] 7. Polar nodules conspicuously projecting inward) 40m.) the cell, wall poh eee ee es a eel a ........O. nodulosa 7. Polar nodules projecting outward (sometimes with) ‘a ‘slight inner swelling also) 00 ..2205...0. 4 He RR OEE aes 8. Cells elongate-elliptic to nearly cylindrical, 2—3 times their diameter in length, with subparallel margins .........................O. submarina 8. Cells ellipsoid or ovate, 11/2 times their diameter in length O. lacustris 9. Chloroplasts 1—3—(4) laminate dises or~plates .........0....0..cceeee LO 9. Chloroplasts 4—20—(30) parietal discs or plates which are oval or star-shaped Ly Pee UPTON 1 oN Aw OCR eee A 10. Cells narrowly elliptic, with sharply rounded to apiculate poles: 1 laminate chloroplast). 2.22..40.5.-0.-5... .... O. gloeocystiformis 10. Cells oval or more broadly elliptic, with rounded or bluntly pointed (not apiculate) poles; chloroplasts 1—3—(4).....00.00.0. ial 11. Cells narrowly elliptic, with pointed poles .....0.....00...0.cccceeee O. parva 11. Cells broadly elliptic or oval, with rounded poles.........................:::000 12 12. Cell walls relatively thick; poles very slightly pointed in some individuals; cells often egg-shaped............................ O. novae-semliae 12 nCellwalls thin: polessmoumdeds.0) 04 oh ahs.g ie sheos etapa tnon a aeed ote 13 13Gells small: °3:8—7.5u in diameter, 6—12,, long... 522.04. mx. O. pusilla 13. Cells larger, 9—13u in diameter, 9—19, long................00......... ..O. Borgei 4: (Chloroplasts 46" star-shaped! "plates yc)... cc mee ctestseeecoeeoeetes O. natans 14. Chloroplasts (4)—10—20 parietal discs or small plates.............0..0..00..... 15 15. Cells 29—40u in diameter; chloroplasts numerous; old mother cell wall symmetrically inflated ..........0...000000.00.. ee O. gigas 15. Cells 11—15.6u in diameter; chloroplasts 10—20; old mother celliwalliirrectlarly inflated): 2.0 -1.r.1)..2.0cie0.- teats O. elliptica Oocystis Borgei Snow 1903, p. 379 Pl. 51, Fig. 10 Unicellular or crowded in groups of 2-8, inclosed by the old mother cell wall; ellipsoid or ovate cells with the poles broadly rounded and smooth; chloroplasts 1 or as many as 4 parietal plates, each with a pyrenoid; cells (9)-12-13 in diameter, (9)—-10-19p long; colony of 8 cells, up to 31 in diameter, 46, long. Lemmermann (1903) has assigned this species, as a variety, to O. gigas. Common in the plankton of soft water lakes; often appearing among filamentous algae in shallow water. Mich., Wis. Oocystis crassa Wittrock in Wittrock & Nordstedt 1880, p. 117 Pitot. Kig.9 Unicellular or in colonies of 2-8, inclosed by a much swollen and gelatinized mother cell wall; cells ovate, the poles broadly rounded and furnished with a nodular thickening; chloroplasts several (as many as 10) large parietal discs, with pyrenoids usually present; cells 10-20, in diameter, 14-26, long. Rare; in plankton. Mich., Wis. [ 248 ] Oocystis elliptica W. West 1892, p.736 Plot Bigs Colony composed of 4-8 oblong-ellipsoid cells inclosed by the irregularly swollen old mother cell wall; poles of the cells broadly rounded and without polar thickenings; chloroplasts numerous (as many as 20) parietal discs, apparently without pyrenoids; cells 11-15.6, in diameter, 20-21.4—( 25)» long. Common in the plankton of many soft water lakes and ponds; frequent in ditches and swamps, especially where there are luxuriant growths of algae and where the water is rich in organic acids. Mich., Wis. Oocystis elliptica var. minor West & West 1894, p. 14 Cells smaller than in the typical plant, 7-10 in diameter, 15-22u long. Common in plankton. Wis. Oocystis Eremosphaeria G. M. Smith 1918, p. 630 Pl. 51, Fig. 12 Plants unicellular, usually solitary, sometimes in a group of 2 or 4 within the old mother cell wall; cells narrowly ovate, the poles broadly rounded and furnished with a large nodular thickening; chloroplasts numerous, as many as 60 parietal, lenticular discs, each with a pyrenoid; cells 20-25-(31), in diameter, 35-45, long. The larger specimens always seem to be found in habitats where there is a rich mixture of algae in shallow, warm water. Plankter; in many lakes and sloughs. Mich., Wis. Oocystis gigas Archer 1877, p.105 P1.51, Fig. 14 Plant usually a family of 4 broadly ellipsoid or ovate cells inclosed within a much enlarged, elliptical mother cell wall; cells broadly rounded at the poles, which are smooth and without nodules; chloroplasts many parietal discs; pyrenoids not observed; cells 29--35-(40) » in diameter, 40-51.8y long. Rare; in plankton. Mich., Wis. Oocystis gloeocystiformis Borge 1906, p. 23 Pl. 51, Fig. 13 Plant usually composed of a family of 2 or 4 ellipsoid cells inclosed within the old mother cell wall; cells with narrowed and sharply rounded poles, without nodular thickenings; 1 parietal chloroplast in each cell, pyrenoid lacking; cells (8)—11p in diameter, 8-18.5, long. The poles of the cells of this species are somewhat produced to [ 244 ] form blunt points, giving an appearance of nodular thickenings. This may be interpreted as a modification of the nodule character which is common to many species, and from the evidence at hand it would seem logical to include O. gloeocystiformis with that section of the genus characterized by the possession of polar nodules. Our specimens compare more closely with the plant figured by Borge (1906) than with those shown by Smith (1920). Among other algae in a few soft water lakes and swamps. Wis. Oocystis lacustris Chodat 1897, p. 119; 1897a, p. 296 Pl. 54, Fig. 1 Plants usually in families of 2-8 within enlarged, oval mother cell walls; cells broadly elliptic or moniliform, the poles furnished with large nodular thickenings; chloroplasts 1-8 parietal plates, usually containing 1 pyrenoid; cells 12-20, in diameter, 16-28, long. Common in the plankton of several soft water lakes. Mich., Wis. Oocystis natans (Lemm.) Wille 1911, p. 58 Cells ellipsoid with sharply pointed poles, without nodular thickenings, united in families of 8; cells 12-15, in diameter, 23-26 long; chloroplasts 4-8 star-shaped plates. Typical plant not observed in our collections. Oocystis natans var. major G. M. Smith 1918, p. 630 Pl. 54, Fig. 2 A family of 2 or 4 ovate cells inclosed in the much expanded old mother cell wall; poles of the cells rather sharply rounded but without polar nodules; chloroplasts 4-8 in number, parietal, lobed or star-shaped plates, each containing a pyrenoid; cells 16-25, in diameter, 31-38, long; families about 90, in diameter, 120, long. Plankter; common. Wis. Oocystis nodulosa West & West 1894, p. 15 PI. 54, Figs. 6,7 Cells solitary, or 2 within old mother cell wall; ellipsoid to oblong- ellipsoid, with rounded apices bearing a papillate thickening which projects both inward and outward; 16-18, in diameter, 25-30, long. Rare; in plankton. Wis. Oocystis novae-semliae Wille 1897, p. 26 Cells ellipsoidal with thick walls; 4 or 8 individuals inclosed by the old mother cell wall; poles of cells without nodular thickenings; cells 5p in diameter, 8» long. Typical plant not represented in our collections. [ 245 ] Oocystis novae-semliae var. maxima West & West 1894, p. 13 A variety differing from the typical plant by its much greater size, 12-15y in diameter, 19-23 long; colony 23-42 in diameter, 40-52 long. Plankter; in several lakes. Wis. Oocystis panduriformis West & West 1894, p. 15 A family of 4 oblong-ovate cells with emarginate, concave lateral walls; cells broadly rounded at the poles and furnished with a conspicuous nodular thickening; chloroplasts numerous, parietal discs, each with a pyrenoid; cells 23-25, in diameter, 50-61.5p long. Typical plant not represented in our collections. Oocystis panduriformis var. minor G. M. Smith 1916, p. 471 PI. 54, Fig. 11 A variety differing from the typical plant by its smaller size, 12-20 in diameter, 30-41» long; colony of 4 cells up to 59, in diameter, 103, long. Euplankter. Wis. Oocystis parva West & West 1898, Jour. Bot., 36, p. 335 Pl. 54, Fig. 3 One-celled or in families of 2-8 individuals, inclosed by the enlarged mother cell wall of the previous generation; 2-4 generations sometimes involved; cells ellipsoid or fusiform with pointed poles which are not furnished with definite polar nodules; chloroplasts 1 to 3 parietal discs, pyrenoids sometimes present; cells 4—7.5y in diameter, 6-15.6, long; colony up to 43.9 in diameter. Common in the tycho- and euplankton of several lakes and bogs. Mich., Wis. Oocystis pusilla Hansgirg 1890, p.9 Pl. 51, Fig. 15; Pl.54, Figs. 4,5 A colony of 4 ovate cells inclosed by the enlarged mother cell wall; poles of the cells broadly rounded, without nodular thicken- ings; chloroplasts 1 or 2 parietal plates, pyrenoids sometimes present; cells 3.8-7.5, in diameter, 6-12, long. Plankter. Uncommon but found in several lakes. Mich., Wis. Oocystis pyriformis Prescott 1944, p. 357 PI. 54, Figs. 8, 9 Cells broadly pyriform-ovoid, with a prominent apiculation at one pole, the other end broadly rounded; united in families of 2 [ 246 ] or 4; chloroplast massive and parietal with 1 pyrenoid; cells 14-16p in diameter, 16-19» long; colony of 4 cells up to 36 in diameter, 48.8y long. This species should be compared with O. apiculata W. West, a much smaller plant with broadly elliptic cells. Plankter; in a cedar swamp. Wis. Oocystis solitaria Wittrock in Wittrock & Nordstedt 1879, p. 24 Pl. 54, Fig. 10 Often solitary, or in a family of 2-8 cells inclosed by the old mother cell wall; cells ovate or ellipsoid; poles with nodular thickenings; chloroplasts numerous parietal plates, each with a pyrenoid; cells 3-9, in diameter, 7-20, long. Common in the euplankton of lakes; also in tychoplankton among filamentous algae. Mich., Wis. Oocystis solitaria var. major Wille 1879, p. 26 A form differing from the typical by having sharply pointed poles and by its larger size, about 16.5y in diameter, 29» long. Rare; in plankton. Wis. Oocystis submarina Lagerheim 1886, p. 45 Pl. 54, Fig. 12 Usually a family of 2-16 oblong-cylindrical cells, rarely solitary; cells narrowed at the poles and furnished with a nodular thickening; chloroplasts 1-3 parietal plates with 1 pyrenoid each; cells 3-9 in diameter, 7-20y long. Rare; in eu- and tychoplankton. Mich., Wis. GLOEOTAENIUM Hansgirg 1890, p. 10 A free-floating, spherical or quadrangular-ovate colony of 2-8 globose or ellipsoid cells compactly and cruciately arranged within the persistent mother cell wall; cells separated within the colony by dark-colored masses of mucilage containing calcium carbonate, usually appearing as 2 X-shaped bands and sometimes almost entirely masking the inclosed cells, a cap of dark mucilage also appearing between the cells and the colonial membrane; chloroplast massive and indeterminate in shape. There is but 1 species in this genus; it is rather rare and widely distributed. [ 247 ] Gloeotaenium Loitelsbergerianum Hansgirg 1890, p. 10 Pl. 54, Figs. 13, 14 Characteristics as described for the genus; cells globose or ovoid, 18-25-(30), in diameter; 8-celled colony as much as 70 in diam- eter, 80 long. In tychoplankton of lakes, in soft or semi-hard water. Mich., Wis. NEPHROCYTIUM Naegeli 1849, p. 79 A colony of 4-8 cells, varied in shape, ovate, fusiform, hemispheri- cal, or oblong-ellipsoid to reniform, inclosed by the much enlarged persistent mother cell wall, which may gelatinize and coalesce somewhat, permitting daughter colonies to adhere together, thus forming colonial complexes; occasionally 2 generations of cells inclosed by 1 mother cell wall; chloroplast a parietal plate, which becomes very diffuse in older cells; 1 pyrenoid. Key to the Species 1. Cells broadly ovate or hemispherical, 133 times longer than wide_____________ 2 1. Cells lunate, fusiform, or reniform, 2-3 times longer than wide____._____. 3 2. Old mother cell walls gelatinized and persisting as fragments about the colony; cells 13-18 in diameter, broadly ovate or hemispherical... N. ecdysiscepanum 2. Old mother cell wall firm and thick; cells hemispherical or very broadly ovate, up to 28 in diameter. N. obesum 8. Investment of cells formed by gelatinized mother cell walls; cells curved or sausage-shaped_.___-_= N. limneticum 8. Investment of cells formed by persistent and firm mother cell walls______ 4 4Ui@ellssreniforn 22.4 choles a0 atl ey Wa Lead. Ee OSE N. Agardhianum 4x Cells shumatersses sb’ a: 58 tp loa Toe eh 6? ses ele Peek el Gane a a N. lunatum Nephrocytium Agardhianum Naegeli 1849, p.79 [N. Naegelii Grunow] Pl. 54, Figs. 15, 16 Colony ovate, composed of 2-8 cylindrical or reniform cells, twisting so as to give a spiral arrangement within the old mother cell wall; cells 2-7 in diameter, 8-18, long. Rather common in the tychoplankton of several lakes and ponds. Mich., Wis. Nephrocytium ecdysiscepanum W. West in West & West 1896, p. 161 Pl. 54, Fig. 17 Colony broadly ovate, composed of 4-16 ovate, ovoid, or nearly hemispherical cells inclosed by the old mother cell wall, the family adjoined or adhering to other families by the gelatinized and [ 248 ] fragmentary remains of cell walls of previous generations, the complex often forming a fan-like arrangement; cells (13 )-15.6-18u in diameter, 30-32 long; colony of 4 cells about 60.4 in diameter. Rare; in lakes and swamps. Wis. Nephrocytium limneticum (G. M. Smith) G. M. Smith 1933, p. 503 Pl. 54, Fig. 18 Colony subspherical, composed of 4-8 curved, crescent- or sausage-shaped cells with broadly rounded ends; mother cell wall of previous generation completely gelatinized and not persisting as a membrane; cells 7.4 in diameter, 10-25, long. Reported as Gloeocystopsis limneticus G. M. Smith from Wis- consin. Euplankter; in ponds and lakes. Mich. Nephrocytium lunatum W. West 1892, p. 736 Pl. 54, Fig. 19 Colony ovate, consisting of 4-8 lunate, bluntly-pointed cells inclosed by a thin, hyaline membrane and arranged so that the concave wall is directed toward the center of the colony; chloroplast covering the cell wall; cells 4—5y in diameter, 14-18, long. Tychoplanktonic in swamps; in ditches. Wis. Nephrocytium obesum West & West 1894, p. 18 Pl. 54, Fig. 20 Colony broadly ovate, composed of 2-4 broadly ovate to hemis- pherical cells inclosed by a thick membranous integument, the cells broadly rounded at the poles and with one margin strongly convex, the other straight or concave; chloroplast massive, somewhat reticulate and covering the entire wall; cells 14-16-(28) in diam- eter, 30-33-(49 ) » long. This species should be compared with N. ecdysiscepanum. Tychoplankter; in ponds and lakes. Mich., Wis. LAGERHEIMIA (DeToni) Chodat 1895, p. 90 [Chodatella Lemmermann 1898] A solitary, free-floating, moniliform, ovate, or ellipsoid cell with a rather thick wall beset with long, tapering, needle-like setae which are confined to the polar or to the equatorial region; chloroplasts 1-4 parietal plates, with or without pyrenoids. Key to the Species ie Gellspmonilitors 25 ee mee eee oe ee L. citriformis EeeCelistovate Or cllipsoig sewers 2. PN le ee a 2 2. Setae more than twice the length of the cell... L. longiseta 2. Setae shorter, twice the length of the cell or less__.... 3 3. Cells with 2 diverging setae arising near each apex.____ L. quadriseta 3. Cells with more than 2 setae, arising at the apices of the cell. 4. Cells with 2-4 setae arising from each pole; cells ovate L. subsalsa 4. Cells with 3-8 setae arising from each pole; cells oblong-ovate_____- L. ciliata Lagerheimia ciliata ( Lag.) Chodat 1895, p. 90 Pl. 55, Fig. 1 Cells oblong-ovate with 3-8 (usually 6) fine, tapering setae at each pole; chloroplasts 1-4 parietal plates, each with a pyrenoid; cells 6-184 in diameter, 10-21, long; setae 15-20p long. Rare; in plankton. Mich., Wis. Lagerheimia ciliata var. minor (G. M. Smith) G. M. Smith 1920, p. 129 Pl. 55, Fig. 2 A variety with smaller, ovate, cells, 6-7.5, in diameter, 8-10, long; setae up to 20, long. Rare; in plankton. Wis. Lagerheimia citriformis (Snow) G. M. Smith 1920, p. 130 Pl. 55, Fig. 4 Cells ellipsoid, moniliform with knob-like extensions at the poles (giving an Oocystis-like appearance to the cell); 4-8 long tapering setae arranged in a whorl at each pole; 1 parietal chloroplast con- taining a single pyrenoid; cells 8-20 in diameter, 13-23» long without the setae, which are 25-35, long. Rare; in plankton. Mich., Wis. Lagerheimia citriformis var. paucispina Tiffany & Ahlstrom 1931, p.462 Pl. 46, Fig. 4 Cells the same shape as the typical but smaller, 8-9, in diameter, 10-14, long; each pole provided with 2-4 setae. Mich. Lagerheimia longiseta (Lemm.) Printz 1914, p. 60 Pl. 55, Fig. 5 Cells ovate or ellipsoid, with very long setae (more than twice the length of the cell) arranged in a whorl] of 4-10 close to the poles; 1 (?) parietal chloroplast without a pyrenoid; cells 5-8, in diameter, 9-13, long without setae; setae 40-55, long. Rare; in plankton. Mich., Wis. [ 250 ] Lagerheimia longiseta var. major G. M. Smith 1920, p. 130 Pl. 55, Fig. 6 A variety differing from the typical by its pointed ovate cells which are considerably larger, 12-15u in diameter, 15-22y long without setae; setae 45-60, long; described as having 1-2 chloro- plasts, each with a pyrenoid. Rare; in plankton. Mich., Wis. Lagerheimia quadriseta (Lemm.) G. M. Smith Pl. 46, Fig. 11 Cells ovate, with 2 long, diverging setae arising near the apices; cells 46.5 in diameter, 7.5-12 long; setae up to 23, long. Mich. Lagerheimia subsalsa Lemmermann 1898, p. 193 PI. 59,, Fig. 7 Cells ovate, with a tuft of 2-4 setae at the poles; 1 parietal chloroplast with a pyrenoid; cells 2.5-8. in diameter, 5-12» long without setae; setae 7.5-26, long. Rare; in plankton. Mich., Wis. FRANCEIA Lemmermann 1898c, p. 307 Free-floating ovate or ellipsoid cells, solitary or 2-4 together; walls covered with long, slender bristle-like setae which may show a basal swelling or tubercle; chloroplasts 1-4 parietal plates; pyre- noids present or absent. This genus should be compared with Lagerheimia in which the setae are confined to the polar or equatorial regions of the cell wall. Key to the Species ells ellipsaia, chloroplasts 2—4 6A oes Ne F. Droescheri Cells ovate: “chiloroplasts l—2—-(3)) 3, ee F. ovalis Franceia Droescheri (Lemm.) G. M. Smith 1933, p. 505 PI. 56, Figs. 1-3 Cells broadly ellipsoid, the wall covered with stiff, straight, spine-like bristles without tubercular thickenings at their bases; chloroplasts 2—4 parietal plates; cells 5-124 in diameter without setae, 9-16y long; setae 15-22, long. Euplankter. Mich., Wis. Franceia ovalis (Francé ) Lemmermann 1898c, p. 308 Pl. 56, Fig. 4 Cells ovate; chloroplasts 1-2-(3) parietal plates; cells 7-10, in diameter, 13-17, long without setae; setae 15-23, long. Rare; in plankton. Mich., Wis. [ 251 ] DIMORPHOCOCCUS A. Braun 1855, p. 44 Colony free-floating; cells arranged in groups of 4 on the branched wall fragments of the previous generation, not inclosed in mucilage; quartets of cells composed of 2 ovate or subcylindric and 2 reniform or cordate individuals; 1 chloroplast, parietal, with 1 pyrenoid. Dimorphococcus lunatus A. Braun 1855, p. 44 Pl. 55, Fig. 8 Cells in groups of 4 on the ends of fine, branched threads com- posed of the fragments of the mother cell wall, the 2 inner cells of the quartet ovate or subcylindric, the 2 outer cells cordate; cells 4-15y in diameter, 10-25, long; chloroplast 1, a parietal plate nearly covering the entire cell wall in mature individuals. Common and widely distributed; especially in the plankton of soft water lakes and acid bog ponds. Mich., Wis. ANKISTRODESMUS Corda 1838, p. 196 Cells acicular, crescent-shaped, or narrowly fusiform; solitary or clustered in fascicles, sometimes straight, usually curved, and often twisted about one another; without a gelatinous envelope. Chloro- plast a thin, parietal plate covering most of the cell wall; pyrenoid present or absent. Members of this genus are frequently found in great abundance in small pools, along with species of Scenedesmus, coloring the water green. They are common pioneers in waterlily and other artificial ponds and laboratory aquaria. Care is needed to distinguish some species of Ankistrodesmus from the myxophycean genus Dactylococcopsis. Key to the Species 1. Cells sigmoid or spirally twisted, sometimes wound about one another___. 2 1Y Cells fusiform; ‘straight’ or luuate, not. twisted === = Se 8 2. Cells slender and elongate, spirally twisted about one another, forming bundles: 2 = A. spiralis 2. Cells wider and stouter than above, sigmoid-arcuate, twisted at the apices only, not forming bundles —_____________________-- A. convolutus 3. Cells straight, or nearly so, broadly fusiform, solitary. A. Braunii 3. Cells narrower than above, curved or lunate, or if straight, endingiin long meed|e: points eee 4 4. Cells fusiform or lunate, straight, or curved, Uistallysentanpled) Or Clustered sess eee eee A. falcatus 4. Cells arcuate, dorsal walls straight from the midregion to the sharply pointed apices; cells always solitary. A. fractus [ 252 ] Ankistrodesmus Braunii (Naeg.) Brunnthaler 1915, p. 189 Pl. 46, Fig. 8 Cells relatively broadly fusiform, lateral margins convex but irregularly so, narrowed at either pole to short points (not drawn out into long needle points as in most species of the genus); chloroplasts 2 parietal plates; cells 8-10 in diameter, 20-25-56y long. Tychoplankter. Mich. Ankistrodesmus convolutus Corda 1839, p. 199 Pl. 55, Fig. 3 Solitary or in groups of 2-4 cells, fusiform in shape, twisted and sigmoid; apices sharply pointed and often twisted in opposite directions; cells 3-4.5, in diameter, 15-25, long. Common in the tychoplankton. Mich., Wis. Ankistrodesmus falcatus (Corda) Ralfs 1848, p. 180 Pl. 56, Figs. 5, 6 Cells needle-like to somewhat spindle-shaped, solitary or in clusters of 2-32 individuals, not inclosed in a colonial sheath; chloroplast 1, a parietal plate without pyrenoids; cells 2-6 in diameter, 25-100» long, sometimes longer. Ubiquitous; intermingled with other algae and most commonly found in acid water habitats of high temperatures where there is a dense conglomeration of unicellular and colonial algae. Mich., Wis. Ankistrodesmus falcatus var. acicularis (A. Braun ) G. S. West 1904, p. 223 Pl. 56, Fig. 16 Cells solitary and almost straight, the outer wall slightly curved in the median portion, extended into long, finely drawn out apices; chloroplast extending over 24 of the cell wall; cells 2.54 in diameter, 36-65, long. Tychoplankter; rare in several lakes. Mich., Wis. Ankistrodesmus falcatus var. mirabilis (West & West) G. S. West 1904, p.224 Pl. 56, Fig. 10 Cells sigmoid or lunate, apices gradually tapering to fine points; cells solitary, 2-3 in diameter, as much as 150, long. Generally distributed. Mich., Wis. [ 253 ] Ankistrodesmus falcatus var. stipitatus (Chod. ) Lemmermann 1908, p. 176 Pl. 56, Figs. 14, 15 Cells lunate (rarely almost straight), attached at one pole to filamentous algae or other submerged aquatics; usually gregarious, forming clusters of 2-8; cells 3-4» in diameter, 18-22p long. Plankter. Wis. Ankistrodesmus falcatus var. tumidus (West & West) G. S. West 1904, p. 224 Pl. 56, Fig. 9 Cells lunate or fusiform, the ventral margin decidedly tumid in the midregion, 4.5-6.5, in diameter, 61-73» long. Rare; in plankton. Wis. Ankistrodesmus fractus (West & West) Brunnthaler 1915, p. 189 Plro6a hig. 7 Solitary, arched-fusiform or arcuate cells, the outer wall convex in the median portion only, with almost straight walls extending to the sharply pointed apices, the inner margin concave in the median portion, straight toward the apices; cells 2.8» in diameter, 40-43.5p long; chloroplast divided into 4 portions by deep folds or incisions. Rare; in the plankton of Sphagnum bogs. Wis. Ankistrodesmus spiralis (Turner ) Lemmermann 1908, p. 176 Pl, 56, Figs. 11, 12 Cells spindle-shaped, spirally twisted into bundles of 4-16 cells; cells 2-3, in diameter, 25-35, long; chloroplast a parietal plate without a pyrenoid. Common in a variety of ponds and lakes; tycho- and euplanktonic. Mich., Wis. DACTYLOCOCCUS Naegeli 1849, p. 85 Pseudo-filamentous, consisting of ovate or fusiform-elliptic cells attached end to end, filaments breaking up to form single, scattered cells or small chains of cells; chloroplast a parietal plate, with or without a pyrenoid. See G. M. Smith 1933, p. 507, for a discussion of the systematic position of this genus. [ 254 ] Dactylococcus infusionum Naegeli 1849, p- 85 Pl. 56, Fig. 13 Fusiform cells, either solitary or attached pole to pole to form false, branched filaments or chains; chloroplast a_parietal plate, sometimes with a pyrenoid; cells 2.5-3.5, in diameter. From a laboratory culture. Wis. (Smith). CLOSTERIOPSIS Lemmermann 1899a, p. 124 Cells long and needle-like, tapering to sharp points at both ends; chloroplast a lobed plate extending almost the entire length of the cell and containing a row of pyrenoids. Closteriopsis should be compared with Closterium and Ankistro- desmus. It is shaped much like some of the very slender species of the former genus in which, however, there are two chloroplasts, one on either side of a central nucleus. It is differentiated from Ankistrodesmus on the basis of its greater size, stouter proportions, and the axial row of pyrenoids. Closteriopsis longissima Lemmermann 1899a, p. 124 [Ankistrodesmus longissimus (Lemm.) Wille] Pl. 57, Fig. 1 Cells long and very narrowly spindle-shaped, the ends tapering to fine points; chloroplast a parietal, lobed plate; cells 3.5-6y in diameter, 190-240-(530) u long. Rare; in the plankton of a few soft water lakes. Wis. Closteriopsis longissima var. tropica West & West 1905, p. 31 Pl. 57, Figs. 2, 3 A variety of stouter proportions than the typical plant and not tapering to a fine point but bluntly tipped at the poles; cells 6—7.5p in diameter, 225-370, long. Plankter. Wis. SCHROEDERIA Lemmermann 1898c, p: 311 Free-floating, unicellular, acicular, fusiform or straight, tapering at the poles and forming long fine setae, one of which may terminate in a disc or may be bifurcated near the end to form a pair of recurved, bristle-like spines; 1 parietal chloroplast covering most of the cell wall, with 1-3 pyrenoids. Key to the Species Cells as much as 20 times their diameter in length; Smimes ts Dg lonpg: «seem ene ceeee raee kien S. setigera Cells smaller, not more than 10 times their diameter ma lempth-xspines PO—1Gu tome etek S. Judayi [ 255 ] Schroederia Judayi G. M. Smith 1916, p. 474 Pl. 57, Figs. 5,6 Cells fusiform, straight or arcuate, the poles narrowed and ex- tended into long setae, one of which terminates in short bifurcations; 1 chloroplast, with a single pyrenoid; cells 2.5-6. in diameter, 45-63, long, including the setae, which are 10-16y long. This species resembles an unattached Characium and should be compared with some of the species of that genus. Rare; in euplankton. Mich., Wis. Schroederia setigera (Schroed. ) Lemmermann 1898c, p. 311 Pl. 57, Fig. 4 Cells fusiform, mostly acicular, the poles extended into long, fine setae, one of which is bifurcate near the tip, forming recurved bristles; chloroplast plate-like, covering most of the cell wall, usually with 1 pyrenoid; cells 3-6, in diameter, 60-85, long, in- cluding the setae, which are 13-17, long. In plankton of lakes. Wis. SELENASTRUM Reinsch 1867, p. 64 A colony of 4-16 lunate or sickle-shaped cells with acute apices, the dorsal or convex walls adjacent; not inclosed by a gelatinous envelope; chloroplast 1, parietal, lying along the convex wall, usually with 1 pyrenoid. Species of this genus should be compared with Kirchneriella which has somewhat scattered lunate cells within a gelatinous envelope. Key to the Species 1. Cells decidedly sickle-shaped, 19-28 from tip to tip___________ S. gracile 1. Cells lunate (crescent-shaped ), or arcuate but not sickle:shaped, mostly: smaller. .- 6. ee eee 2 D, Gellis areata, Usain, tin Clam S. Westii 2-1 Cellsilunate,slarteninididmeter. 2-22 eee 8 3. Cells 5—8u in diameter, 16—42u from tip to tip.................... S. Bibraianum 3. Cells (2)—3 in diameter, 7-94 from tip to tip S. minutum Selenastrum Bibraianum Reinsch 1867, p. 64 Pl. 57, Fig. 9 Colony ovate in outline, composed of 4-16 lunate or sickle-shaped cells with sharp apices and arranged so that the convex surfaces are apposed and directed toward the center of the colony; cells 5-8. in diameter, 20-38, long; distance between apices 16—42u. Rare; in several lakes, mostly soft water, and in acid swamps. Mich., Wis. [ 256 ] Selenastrum gracile Reinsch 1867, p. 65 PI. 57, Fig. 11 Colonies of 8-64 sickle-shaped cells in irregular arrangement, but with the convex surfaces apposed; apices of the cells sharply pointed; chloroplast a parietal plate along the convex wall, without a pyrenoid (?); cells 3-5 in diameter, 19-28, between apices. In tychoplankton of lakes and swamps. Mich., Wis. Selenastrum minutum (Naeg.) Collins 1909, p.171 Pl. 46, Fig. 10 Cells often solitary or in small families, irregularly arranged, crescent-shaped, the poles bluntly pointed; cells 2-3 in diameter, 7-9. between apices. Mich. Selenastrum Westii G. M. Smith 1920, p. 133 Pl. 57, Fig. 10 Colony small, composed of 2-8 slender, lunate or arcuate (but not sickle-shaped) cells, arranged with their convex walls apposed; chloroplast a parietal plate lying along the convex wall; pyrenoid lacking (?); cells 1.5-2.51 in diameter; 15-18 between apices. Rare; in euplankton. Mich., Wis. KIRCHNERIELLA Schmidle 1893, p. 83 Free-floating or caught among larger algae; a colony of strongly curved, lunate, sickle-shaped or twisted fusiform, sometimes cylin- drical cells, inclosed by a gelatinous envelope in which there is no regular arrangement of individuals although young colonies may have even numbers of individuals, and these are usually arranged so that the convex walls are together; chloroplast a parietal plate along the convex wall, with 1 pyrenoid. Key to the Species 1. Cells inclosed by the persistent mother cell wallofithe laskicemerationes = en epee K. subsolitaria 1. Cells inclosed by a copious mucilaginous sheath __________»_________ 2 2. Cells vermiform cylinders, rounded at the poles ____________________________-___- 8 2. Cells lunate, sickle-shaped, sharply or bluntly pointed at the apices 4 3. Cells small, 2u or less in diameter, up to 14u long == K. contorta 3. Cells larger, 2-3u in diameter, up to Dap wlonp) spinal ys tis ecd meee seis oe anh ile ee ee ee K. elongata 4, Cells narrowed at the poles, rounded or bluntly pointed_________ K. obesa 4, (Cellsisharply pointed’ at the: poles: =) 20s.) 2) a 3) K. lunaris [ 257 ] Kirchneriella contorta (Schmidle) Bohlin 1897, p. 20 Pl. 57, Figs. 7, 8 Free-floating colonies, usually of 16 twisted, arcuate, cylindrical cells with broad, convex apices, lying irregularly scattered through- out the homogeneous, gelatinous envelope; chloroplast covering the entire wall of the cells, which are 1-2 in diameter, 5.8-10-(14)y long. fae! in plankton of several lakes. Mich., Wis. Kirchneriella elongata G. M. Smith 1916, p. 473 Pl. 58, Fig. 1 Colonies composed of 4-16 elongate-cylindrical, spirally twisted cells which have rounded apices; individuals much entwined near the center of the homogeneous colonial envelope; 1 parietal chloro- plast, without a pyrenoid; cells 2-3» in diameter, 15-25, long; colonies up to 100, in diameter. Rare; in the plankton of several lakes. Mich., Wis. Kirchneriella lunaris (Kirch. ) Moebius 1894, p. 331 Pl. 58, Fig. 2 Colony composed of numerous cells arranged in groups of 4-16 within a close, gelatinous envelope; cells flat, strongly curved crescents with rather obtuse points; chloroplast covering the convex wall; cells 3-8. in diameter, 6.5-13, long; colonies 100-250,» in diameter. Common in the plankton of open water or among mats of algae in the shallow water of acid ponds and lakes. Mich., Wis. Kirchneriella lunaris var. Dianae Bohlin 1897, p. 20 Pl. 58, Fig. 3 A variety differing from the typical in having very strongly curved cells with sharply pointed apices which are not in the same plane; cells 8-5u in diameter, 10-18-(21)» long. Rare; in plankton of several lakes especially in acid habitats. Mich., Wis. Kirchneriella lunaris var. irregularis G. M. Smith 1920, p. 142 Pl. 58, Fig. 4 A variety differing from the typical by having the apices distinctly twisted and very evidently pointing in different directions so that a spiral sigmoid curve is produced; cells 4-6» in diameter, 6-13, long. Tae in plankton of a variety of lakes. Wis. [ 258 ] Kirchneriella obesa (W. West) Schmidle 1893, p. 16 [83] Pl. 58, Fig. 5 Colony composed of many irregularly arranged cells in a wide gelatinous envelope; cells strongly lunate, the outer margin convex and the inner nearly parallel to it, tapering slightly to bluntly pointed apices; chloroplast covering the entire convex portion of the wall; cells 4-6 in diameter, 10-14, long. Rare but widely distributed; in the plankton of many lakes. Mich., Wis. Kirchneriella obesa var. aperta (Teil.) Brunnthaler 1915, p. 182 Pl. 58, Figs. 6,7 A variety in which the cells are less strongly lunate, with the inner margin of the cell describing a much greater arc than the outer; cells 7.4-10 in diameter, 10-14, long. Rare; in the plankton of several lakes. Wis. Kirchneriella obesa var. major (Bernard) G. M. Smith 1918, p. 636 Pioiebic. 2 A variety differing from the typical by having the inner and outer margins nearly parallel, slightly tapering at the apices, which are bluntly rounded; cells 3-5y in diameter, 10-18-(21), long. Rare; in plankton. Mich., Wis. Kirchneriella subsolitaria G. S. West 1908, p. 284 PI. 58, Fig. 8 Plant consisting of 4 strongly curved, crescent-shaped cells ar- ranged together within old mother cell wall, the apices bluntly rounded and not tapering; cells 3-4.5p in diameter, 10-14 long. Euplankter. Wis. QUADRIGULA Printz 1915, p. 49 A free-floating, ellipsoid colony of 2-4-8 long-cylindrical or fusi- form cells with long axis parallel with that of the gelatinous sheath in which they are inclosed; poles of the cells subacute or sharply rounded; chloroplast a parietal plate covering most of the cell wall, or sometimes located along one side; pyrenoid sometimes present. Some species of this genus will be found treated under Ankistrodesmus in a number of manuals. The two genera are separable on the basis of their arrangement in the colony and the common investing sheath, the latter not being present in Ankistrodesmus. [ 259 ] Key to the Species 1. Cells spindle-shaped, numerous and scattered within a gelatinous investment but with the longitudinal axes parallel...» Q. lacustris 1. Cells arcuate, lunate, or straight, arranged in bundles of 4 within the gelatinous investment, fewer in number than above 2 2. Cells straight, margins subparallel in the median portion; poles rommded = es Q. closterioides 2; Cells arcuate or lunate; poles pointed QO. Chodatii Quadrigula Chodatii (Tan.-Ful.) G. M. Smith 1920, p. 138 [Ankistrodesmus Chodati (Tan.-Ful.) Brunnthaler] Pl. 59, Figs. 1-3 Free-floating; cells long, fusiform to slightly lunate or arcuate, tapering to subacute points, longitudinally arranged within a broadly fusiform colonial envelope; chloroplast a parietal plate with a median notch, containing 2 pyrenoids; cells 3.5-7 in diameter, 30-80 long; colony as much as 250, long. Rare; in euplankton of a few lakes as well as in the tychoplankton of shallow water. Mich., Wis. Quadrigula closterioides (Bohlin) Printz 1915, p. 49 Pl. 58, Figs. 9, 10 Cells long, straight, but with one margin slightly curved, cylin- drical in the mid-region, tapering to sharply rounded apices, arranged in longitudinal bundles of 4 within a fusiform colonial envelope; chloroplast parietal, covering almost the entire cell wall, with a median notch; 1 pyrenoid; cells 4-6, in diameter, 22-35-(45)p long. Common in many soft water lakes. Mich., Wis. Quadrigula lacustris (Chod.) G. M. Smith 1920, p. 189 [Ankistrodesmus lacustris (Chod.) Ostenfeld] Pl. 59, Figs. 4,5 A free-floating, fusiform-shaped colony containing many short, fusiform cells, mostly arranged in pairs; cells straight, but with slightly convex margins, tapering to blunt points; chloroplast a parietal plate, sometimes twisted in the cell, without a median notch, with 1 pyrenoid; cells 3-5y in diameter, 20—25y long. Rare; in the plankton of many lakes, mostly soft water. Mich., Wis. TETRAEDRON Kuetzing 1845, p. 129 Cells solitary and unattached; of various shapes, triangular and flat, pyramidal, polyhedric; the angles entire, with or without spines, [ 260 ] w or variously lobed to form dichotomous or trichotomous spine-tipped processes; chloroplasts one to many parietal discs or plates; pyrenoids usually present. Key to the Species 1. Angles or poles of the cell smooth or tipped with spines but not extended and produced to form processes 2 1. Angles of the cell extended and produced to form short or long arms or processes, branched or unbranched... 19 2 Auelesstipped, Withl|| =o" SpINcs 222 sas wen amane cm eee 2A 8 ZaPancies smoot, or with a blunt spapillase se ee es eee 16 Sr anglesior tierce lvalluimione plane 22 2a ee eee Ss 4 oe anlples of theycell not all. ini oneplanc 7 9 em OC HSNCTES CONES Hae les meas Se avis fo Pad en se ute eee er T. lunula Fame lS en Ota eLeSCent-Siid PEC a= =e au nie ee Se ee ee 5 bell Sea Det eae ee ee ee ee eran ek eee T. trigonum Se Gellsmmore tthan3-an tiled 2a ne ee ee ee 6 CBs, CCGA Sa al (2 at ele a near aG a RL T. caudatum GmCellswrtcan gles cme as 28 RL reg ne el eh a if 7. Cells deeply constricted on 2 sides, each of the four lobes tipped with a spime—_ T. arthrodesmiforme ie (Gellsmot*deeply, constricted on‘ 2sidesi= 2 27 sts 2) SAS 8: Gells tetrahedraly anargins concave 2-227 T. regulare 8. Cells quadrangular, margins straight____________----_-_-----_--_-- T. quadratum 9. Cells broadly ellipsoid in outline but with 3 scarcely evident angles,-each tipped with a’short spine 222. T. obesum 9. Cells polyhedral or pyramidal, with 4-5 angles 10 OM Gelisfwith Ahan ples A 2): set om epee So Se ee ed 8 11 HOSGelis avitht oranges 21! os el alee T. pentaedricum HTS Giga ryr An ele ee gh T. regulare (see var. torsum) 11. Cells lobed, the lobes contorted, usually not all in the same plane. 12 Oe Cell cwalleveniiCose e:2- = oe hy Bree Een We Es T. verrucosum Es Gel lea src tines 2 oe ae ee, ee ee 13 13. Angles of the cell tipped with 2 spines_______________________ T. bifurcatum dis ae Ani mlestOtstaedce ll with hss pine: ak aE ea 14 14. Lobes of the cell long and gradually tapering, tipped with a long, slender spine, the lobes forming 2 semicells and cruciately arranged, 2 in one plane and 2 in another-_._._._.----.-.----.---------- *_T. Victoriae 14. Lobes of the cell short and abruptly tapering, all in different planes 15 15. Lobes twisted over one another, the angles furmished with aslonpispine. «2 = T. arthrodesmiforme var. (compare with T. Victoriae ) 15. Lobes shorter and not twisted over one another; angles tipped! witht a shortispine =< hee! Pe T. regulare 165) Gells*regularly. or irregularly pyramidal .."-- Le 16. Cells not pyramidal; triangular or quadrangular______________________ 18 17. Cells regularly pyramidal, symmetrically 4-lobed_._________ T. tumidulum iveaGe lsvrrecularly o- Ol G-l@ueG ee ee T. gigas aie C@clistetianelilar, etemeenmemnes oe ete POL Ne a ee T. muticum TS meC@ells cqmaciam pul dns) ceeneeme Teel Pies eRe it T. minimum [ 261 ] 19. Processes not divided and without secondary lobes — 20 IG MProcessesnaiviGd ed aot =a Ole tet a te maaan aed TT 293 20. Processes very short, angles scarcely produced at all tipped wath 2 spines. 512013 Vel ae eee ee T. armatum 20.eAngles, ‘markedly, produced)» =. — AJA) 2 een ee oa 21 21. Cells cruciately lobed, the lobes in 1 plane, deeply, bifurcatelatithe apices.) 5 sa. ae ee Bele ae ead, T. pusillum 21. Cells not cruciately lobed; lobes not all in the same plane... 2.2 22. Cells tetrahedral, pyramidal, the lobes long and tapering, tipped with) 3. spines se 0) Civ i ee T. hastatum 22. Cells with short, asymmetrical lobes, not at all or scarcely tapering, tipped with 2-3 blunt spines._.___»_-_ T. asymmetricum 23; Opes allcin the same tp larie mut Jee ae 2) eee 0h) il elles eal alma See OMe 24 23, Wobes not allyimicthe saine) plane see lt eae leat ee ean Hil 24. Cells definitely 4-lobed, the lobes forming ain shaped igure (sete ve wih vont ei SEL APRIL a CR T. constrictum 24.) Cellssnot definitely vil -shaped x. sa4 Ws Lies he ap SL eee 25 25. Lobes and lobules of the cell long and slender, tipped with 2 spines 26 25. Lobes short and broad, rarely with secondary lobes —_--_____ T. cruciatum 26. Processes long and slender, much branched_______________________ T. gracile 26. Processes short, rarely with secondary lobes... T. lobulatum 27. Angles extended into very short, broad processes winieh lravershorty secondary Wobes suse. mae ee eee T. enorme 27. Angles extended into long, tapering processes with) long: narrow secondary lepes 2 es eee 28 28. Processes much branched to the fifth order.....8.42. a NES Se T. lobulatum var. polyfurcatum 28: Processesswith: oor less Series of divisions. 2+ eee es 29 29. Body of the cell narrow, processes longer than) thediametemobthe.cellt. 22 DU ew eee ee ae T. limneticum 29. Body of cell thick; processes shorter than the\drameéter: ob thercelli tana a, ae et ol a T. planctonicum Tetraédron armatum (Reinsch) DeToni 1889, p. 611 i PI. 59, Figs. 6,7 Cells irregularly triangular and lobed, the angles scarcely or not at all produced, but furnished with a pair of widely separated spines; the angles of the cell sometimes not all in the same plane, so that 1 or 2 pairs of spines are seen one above the other when viewed from the side; cell 30—47.6, in diameter. Rare; in euplankton. Mich., Wis. Tetraédron arthrodesmiforme (G. S. West) Woloszynska 1914, p. 203 Pl. 59, Fig. 8 Cells quadrate in outline, symmetrically incised to form 2 lobes; a spine on each of the 4 angles; 2 sides of the cell subparallel, convex, the isthmus bordered by a widely open sinus; cells up to 56u in diameter. Typical form not reported from our region. [ 262 ] Tetraédron arthrodesmiforme var. contorta Wotoszynska 1914, p. 203 Pl. 59, Figs. 9, 10 A variety differing from the typical by having the 4 lobes twisted and extending in at least 2 planes, a character which is particularly evident when seen from the ‘side’; cell 25-32-(50) in diameter, up to 60, in the longest dimension. Rare; in euplankton. Wis. Tetraédron asymmetricum Prescott 1944, p. 357 Pl. 59, Figs. 11-13 Cell quadrangular in outline, unsymmetrically incised to form 2 major lobes with an isthmus bordered by a widely open sinus, the 2 major lobes slightly bilobed, the lobules tipped with 2 or 3 short spines; cells 10-18, in their longest dimension. This species should be compared with T. irregulare (Reinsch) DeToni. Rare; in euplankton and tychoplankton. Wis. Tedraédron bifurcatum (Wille) Lagerheim 1893, p. 160 Pl. 59, Fig. 14 Cells irregular tetrahedrons, the lobes tipped by 2 short spine- bearing processes, the margins of the cell concave between the apices of the lobes; maximum diameter of the cell 55-60x. Rare; in plankton of lakes; tychoplanktonic in swamps. Wis. Tetraédron bifurcatum var. minor Prescott 1944, p. 358 Pl. 59, Figs. 15, 16 A form differing from the typical by its small size and in having the lobes bifurcated, the lobules rather stu1t and tipped with a short spine; cells up to 22.5y in their maximum diameter. Rare; in tychoplankton. Wis. Tetraédron caudatum (Corda) Hansgirg 1888a, p. 131 PI. 59, Figs. 17, 24, 25 Cells flat, 5-sided, the angles rounded and tipped with a short, sharp spine, the sides between the angles concave, but with one margin narrowly and deeply incised; cells in their longest dimension 8-15—(22) u. Tetraédron caudatum var. incisum Lagerheim, reported from Michigan by Taft (1939), does not seem to be separable from the typical form. The sinus of the incision on the margin is very narrow. In tychoplankton; in shallow water of lakes and in swamps. Wis. [ 263 ] Tetraédron caudatum var. longispinum Lemmermann 1898d, p. 151 Pl. 59, Figs. 20-22 A variety differing from the typical by having longer spines which are directed at right angles to the flattened surface of the cell, 2 turned in one direction, 3 in the opposite; cells 8-18, in diameter; spines 3-8, long. Euplankter; in lakes. Wis. Tetraédron constrictum G. M. Smith 1920, p. 122 Pl. 59, Fig. 28 Cells quadrangular in outline, tetragonal, 2 sides subparallel, the other 2 deeply concave as seen in front view, the angles extended into slightly tapering processes which are dichotomously branched and tipped with a short spine; in side view fusiform, the processes at the superimposed poles of the cell not quite in the same plane but slightly turned at different angles; cells 5-8. in diameter, without processes, 8u thick, 18-25, in their longest dimension. Rare; in euplankton. Wis. Tetraédron cruciatum ( Wallich) West & West 1902a, p. 198 Cells cruciately 4-lobed, the lobes bifurcate, one division of 2 lobes usually again divided; lobes and lobules tipped with 2 short spines; margin of the cell deeply concave between the lobes, more deeply so on 2 sides than on the others; cells (larger forms) 42-54y or (smaller forms) 17, in diameter. Typical plant not reported from our region. Tetraédron cruciatum var. reductum Prescott 1944, p. 358 Pl. 59, Fig. 23 Cell flat, irregularly cruciform or sometimes 3-lobed, the lobes bifurcate, the lobules tipped with a short spine; margins of the cell concave on 2 opposite sides, straight or only slightly concave on the other sides; cells 28-30, in diameter, up to 54, in the greatest dimension. Tychoplankter; in swamps. Wis. Tetraédron duospinum Ackley 1929, p. 304 Pl. 46, Figs. 22, 23 This species, described as new from Michigan and illustrated (Ackley, l.c., Pl. 35, Fig. 14), appears to be a Cystodinium or some other encysted dinoflagellate. I have not seen type specimens, how- ever. Mich. [ 264 ] Tetraédron enorme (Ralfs) Hansgirg 1888a, p. 132 Pl. 52, Figs. 6,7 (var.); Pl. 59, Fig. 19 Cells poly- or tetrahedric, the angles shortly produced and bilobed, the lobes bifurcate and tipped with short spines; margins of the cell concave between the angles, the processes not all in the same plane; cells (25)-30-( 45), in diameter. Common in the tychoplankton of several lakes; generally distrib- uted. Mich., Wis. Tetraédron enorme var. pentaedricum Prescott 1944, p. 358 PI. 59, Fig. 18 Cells 5-sided in outline, the sides straight or slightly convex, with pairs of narrow bifurcated processes extending in all planes, the processes tipped with short spines; cells 50-55, in diameter, without processes. This form differs from the typical plant by its straight margins and narrow bifurcated processes extending from the angles. It is similar to Borge’s figure of T. enorme, which I judge to be typical. Rare; in plankton. Wis. Tetraédron gigas (Wittr.) Hansgirg 1888a, p. 131 Cells relatively large, irregularly 5- or 6-angled, the processes broadly rounded, with the margins between the angles broadly concave; cells 35-45, in the short diameter, 65-75, long. Typical form not reported in our region. Tetraédron gigas var. granulatum Boldt ex Brunnthaler 1915, p. 148 A variety differing from the typical by the possession of finely punctate walls. Mich. Tetraédron gracile (Reinsch) Hansgirg 1889, p. 19 Pl. 60, Fig. 1 Cells flat, cruciform, rectangular in outline, the angles extended into narrow, twice furcated processes which are tipped with 1 or 2 short spines, the margins deeply concave between the processes; cells 15-30, in diameter, without processes, 35-40, wide including processes; 6-12, thick. Rare; in euplankton. Mich., Wis. Tetraédron hastatum (Reinsch) Hansgirg 1888a, p. 132 PI. 59, Fig. 26 Cells pyramidal, the angles extended into narrow, slightly taper- ing, unbranched processes which are tipped with 2 or 3 short spines, [ 265 ] the margins concave; cells 28—36y in diameter, processes 8p wide at the base. Rare; in plankton. Wis. Tetraédron hastatum var. palatinum (Schmidle ) Lemmermann 1902, p. (247) Pl. 59, Fig. 27 Cells pyramidal, the processes longer and more graceful, not tapering, tipped with 3 short spines, the margins of the cell convex; cells 4-14, in diameter without processes. Euplankter. Wis. Tetraédron limneticum Borge 1900, p. 5 Pl. 60, Figs. 2-4 Cells pyramidal, 4-angled, the angles produced into relatively narrow, once or twice furcated processes which are tipped with short spines, the margins of the cell concave between the angles; cells 30-55-( 85) in diameter including processes. Common and generally distributed in many lakes. Mich., Wis. Tetraédron limneticum var. gracile Prescott 1944, p. 358 Pl. 60, Fig. 5 Cells pyramidal or tetragonal, the angles extended into bifurcate processes which are tipped with 2 or 3 stout spines, the margins of the cell concave between the processes; bases of the processes adjoining so that there is scarcely a cell body; cells 40-46.8, in diameter; processes 6-8 wide. Euplankter. Wis. Tetraédron lobulatum (Naeg.) Hansgirg 1888a, p. 132 Pl. 60, Figs. 6, 7 Cells tetragonal, mostly pyramidal (or flattened); processes short and stout, bifurcate at the apices; cells 35-40, in diameter. Euplankter. Mich., Wis. Tetraédron lobulatum var. crassum Prescott 1944, p. 359 Pl. 60, Fig. 8 Cells tetragonal, pyramidal, the angles slightly produced to form relatively wide, short processes which are bilobed, the lobules bi- furcate and ending in short curved spine-like tips; cells 25-30, in diameter. [ 266 ] This form differs from the typical by its broad, bilobed processes and by the lateral walls of the cell being much less concave or emarginate. It differs from var. polyfurcatum G. M. Smith in the form and number of processes. Planktonic in lakes; also found in Manitowish River, Wisconsin. Tetraédron lobulatum var. polyfurcatum G. M.Smith 1916, p. 480 Pl. 60, Fig. 11 Cells tetragonal, pyramidal or flattened, the angles extended into processes which are dichotomously divided 3 to 5 times, the lobules ending in 2 or 3 minute spines; margin of the cell concave between the processes; cells 15-25, in diameter without processes, 35-70, in diameter including processes. Rare; in the plankton of many lakes. Wis. Tetraédron lunula (Reinsch) Wille 1911, p. 60 Pl. 60, Figs. 9, 10 Cells lunate, tapering to sharply pointed poles; the outer margin more sharply curved than the inner, which is concave; cells 11-12y in diameter, 25-30, long. Plankter, in a small inlet of the Wisconsin River, Wisconsin. Tetraédron minimum (A. Braun) Hansgirg 1888a, p. 131 Pl. 60, Figs. 12-15 Cells small, flat, tetragonal, the angles rounded and without spines or processes, lobes sometimes cruciately arranged; margins of the cell concave, with one frequently incised; cells (6)-14.5-20, in diameter. Common in the tychoplankton and euplankton of many lakes and ponds. Mich., Wis. Tetraédron minimum var. scrobiculatum Lagerheim 1888, p. 591 A variety differing from the typical by having deeply punctate walls. Mich. Tedraédron muticum (A. Braun) Hansgirg 1888a, p. 131 Pl. 60, Figs. 16, 17 Cells small, flat, triangular, the angles without spines or furcations; sides of the cell emarginate or slightly convex; cells 6-1$, in diameter. A common species in many habitats, but because of its small size it is easily overlooked in rich tychoplanktonic collections. Mich., Wis. [ 267 ] Tetraédron muticum fa. punctulatum (Reinsch ) DeToni 1889, p. 600 Pl. 60, Fig. 18 Cells flattened, triangular, the angles sharp but without spines; margins slightly convex; wall granular; cells 15-20, in diameter, 8-10u thick. Euplankter. Wis. Tetraédron obesum (West & West) Wille ex Brunnthaler 1915, p. 154 Pl. 60, Figs. 19, 20 Cells ovate or broadly elliptic in outline, but with 3 lobes which are scarcely produced, one lobe lateral to the long axis of the cell, all lobes tipped with a short sharp spine; cells 15y in diameter, 31-35, long. Plankter; in lakes and ponds. Mich., Wis. Tetraédron pentaedricum West & West 1895, p. 84 Pl. 60, Figs. 21-23 Cells irregularly 5-lobed, with 1 lobe extended in a different plane from the others; angles sharply rounded, the apex of each lobe furnished with a sharp spine; diameter of cells 18-21,. Rare; in euplankton. Mich., Wis. Tetraédron planctonicum G. M. Smith 1916, p. 479 Pl. 60, Figs. 27, 28 Cells polyhedral-pyramidate, 4- or 5-angled, with convex sides, the angles produced into once- or twice-furcate processes, becoming narrower in the furcations, the lobes tipped with 2 or 3 spines; cells 18-30, in diameter without processes, 45-60, including the processes. Common in the plankton of many lakes. Mich., Wis. Tetraédron pusillum (Wallich) West & West 1897, p. 237 Pl. 60, Fig. 29 Cells cruciform, deeply 4-lobed, concave between the lobes, the lobes bifurcate at the apices, all in one plane; cells elongate-elliptic in side view; 10 in diameter, 25, long. Plankter; found in several lakes; common. Mich., Wis. Tetraédron quadratum (Reinsch) Hansgirg 1889, p. 18 Pl. 46, Figs. 21, 21a Cells quadrangular in front view, the lateral margins straight with sharp angles which are furnished with a short spine; membrane 2-layered, up to 4.5, thick; cells 17-34,» in diameter. Mich. [ 268 ] Tetraédron regulare Kuetzing 1845, p. 129 Pl. 60, Figs. 24-26 Cells tetragonal, pyramidal, the angles produced to form stout lobes, narrowly rounded and tipped with a single, stout spine; the margins of the lobes convex or straight, lateral walls between the lobes concave; cells (14)—45-51.8 in diameter. Plankter; in many lakes and ponds; generally distributed. Mich., Wis. Tetraédron regulare var. bifurcatum Wille 1884, p. 12 PI'6!, Figvl Cells tetragonal, pyramidal, the sides convex or slightly concave, the angles broadly rounded and tipped with 2 stout often curved spines; cells 30-36 in diameter including spines. Tychoplankter; in shallow water of lakes and sloughs. Mich., Wis. Tetraédron regulare var. granulata Prescott 1944, p. 359 Pl. 61, Figs. 2,3 Cells large, pyramidal, the lobes broad and stout with convex margins, the angles broadly rounded and tipped with a single short spine which may be reduced to a mere papilla; wall punctate and covered with small granules or roughenings; cells 35-51.8. in diameter. Plankter; in several lakes. Wis. Tetraédron regulare var. incus Teiling 1912, pp. 274, 277 Pl. 61, Figs. 4-7 Cells tetragonal, flat or pyramidal, with concave lateral margins, the angles slightly produced to form short lobes each tipped by a relatively long spine; cells 15-20, in diameter without spines, up to 37, in diameter including spines. Plankter; in several lakes. Wis. Tetraédron regulare var. incus fa. major Prescott 1944, p. 359 P1.61, Fig. 13 Cells tetragonal, pyramidal, the margins straight or slightly convex, the angles produced to form long, stout spines; cells 35-50,» in diameter, including spines; spines 12-13.5, long. Plankter; lakes and streams. Wis. Tetraédron regulare var. torsum (Turner) Brunnthaler 1915, p. 150 Pl. 61, Figs. 8-10 Cells tetragonal, pyramidal, the lobes narrow and tapering to a spine-tipped apex, twisted so that they are cruciately arranged; [ 269 ] lateral margins convex; sides of the cell concave between the lobes; cells 25-33—( 40)» in diameter. Tychoplankter. Mich., Wis. Tetraédron trigonum (Naeg.) Hansgirg 1888a, p. 130 PI. 61, Figs. 11, 12 Cells flat, 3-angled, the angles tapering to sharply rounded, spine- tipped apices; margins convex; sides of the cell body concave or straight; cells 19-29.8, in diameter. Common in the tychoplankton of several lakes. Mich., Wis. Tetraédron trigonum var. gracile (Reinsch) DeToni 1889, p. 598 Pl. 61, Figs. 14-16 Cells flat, triangular, the angles narrower and more produced than in the typical plant, sometimes curved, tapering acutely and ending in a spine; cells 25-40y in diameter, including the spines. Euplankter. Wis. Tetraédron trigonum var. papilliferum (Schroed. ) Lemmermann ex Brunnthaler 1915, p. 149 A variety with only slightly concave margins, the angles tipped with a blunt, wart-like papilla; cells 12-15, in diameter. Mich. Tetraédron tumidulum (Reinsch) Hansgirg 1889, p. 18 Pl. 61, Figs. 17, 18 Cells tetragonal, pyramidal, the margins straight, concave, or convex; the angles bluntly rounded and sometimes with knob-like extensions; cells 30-53, in diameter. Plankter; in lakes and sloughs. Mich., Wis. Tetraédron verrucosum G. M. Smith 1918, p. 632 Pl. 61, Figs. 24, 25 Cells tetragonal, pyramidal, sometimes with lobes cruciately arranged; margins of the cell convex, the angles ending in a stout, blunt spine; wall coarsely verrucose; cells 65-80% in diameter including the spines, which are 13-18, long. Rare; in euplankton. Wis. Tetraédron Victoriae Wotoszynska 1914, p. 203 Cells deeply lobed to form 2 semicells which are subcruciform in arrangement, the semicells bilobed, with the walls emarginate [ 270 | between the lobes; apices of the lobes rounded and tipped with a short, blunt spine; cells 10-15, in diameter, 20-30, long. Typical form not reported from our region. Tedraédron Victoriae var. major G. M. Smith 1920, p. 119 Pl. 61, Figs. 28, 29 Cells 4-angled, divided into fusiform-shaped semicells, as seen in vertical view, by deep emarginations, the two semicells bilobed and cruciately arranged, each lobe produced into a stout spine; cells 15-20, in diameter, 30-60, long including spines. Euplankter; rare but found in several lakes. Wis. CERASTERIAS Reinsch 1867, p: 68 Unicellular, free-floating, triangular or pyramidal, the angles extended into long, tapering processes, the bases of which comprise the body of the cell; processes all in one plane or in more than one; chloroplast parietal, without a pyrenoid. This genus should be compared with Tetraédron, from which it is separated only on relative size of the cell body. In Tetraédron the main part of the cell is evident, and it may have spines or processes at the angles. In Cerasterias the body of the cell is practically non-existent, being only the bases of the cell lobes. C. irregulare G. M. Smith is to be expected in this area, but in our collections only the European species, C. staurastroides West & West, has been found. It is sometimes listed as Tetraédron stauras- troides (W. West) Wille. Cerasterias staurastroides West & West 1895b, p. 268 (fa. ) Pl. 56, Fig. 8; Pl. 61, Figs. 19, 20 Cells tetragonal, the body narrow and gradually extended into 4 long, slightly tapering processes which have 2 or 4 teeth-like spines (in our specimens) at the apices; the wall of the processes covered with sharply pointed granules arranged in transverse series; body of the cell 10, in diameter; greatest dimension, including processes, 36.5p. Our specimens differ from the typical in having the processes tipped with short teeth. The apices are described as rounded by Brunnthaler (1915, p. 159). Plankter; rare. Wis. POLYEDRIOPSIS Schmidle 1900a, p. 17 Unicellular, free-floating, tetragonal or pyramidal, the angles truncately rounded and furnished with a tuft of 3-10 long, tapering [ 271 ] setae; sides concave, or in some slightly convex; chloroplast a parietal plate covering most of the cell wall, or more massive in old cells, with 1 pyrenoid. Polyedriopsis spinulosa Schmidle 1900a, p. 17 Pl. 62, Figs. 2,3 Characteristics as described for the genus; cells 12-25 in diameter; setae 40y long. Rare; in plankton. Wis. FAMILY SCENEDESMACEAE In this family the cells are adjoined to form definite patterns and colonial aggregates of regular shape. This arrangement is determined by the autospores which, when cut out of the parent protoplast, become definitely related and oriented to one another to form autocolonies in which there are always multiples of 2. These colonies upon being liberated increase in size to form the mature lant. There is a great variety of cell shapes (oblong, fusiform, spherical, triangular, trapezoidal) and arrangement. The colony may be a linear series, a flat plate, a trapezoidal aggregate, or a cluster of radiating fusiform individuals. This family differs from the preceding one (Oocystaceae) in that colonies are formed by the definite adjoining of cells in a regular pattern. Key to the Genera 1. Cells ovoid, fusiform, crescent-shaped, or oblong, arranged with their long axes parallel to form a single or double senies\inel yplaueee = ed ee Scenedesmus (See S. acyminatus, with cells in a curved series. ) 1. Cells of different shape, or otherwise arranged ____------------------______-- 2 2. Cells fusiform or cylindrical, with long axes parallel; quadrately arranged in 2 tiers Tetradesmus 2. Cells arranged otherwise-__._.__—-_--_------_---—-—-_-------- 8 3. Cells spherical, forming pyramidal and multiple colonies of 4; cells bearing long spines______-------------------------- Micractinium 3. Cells not spherical, without spines or with but very short ones______- 4 4. Cells with only their poles adjoined, extending in several planes 6 (See Scenedesmus Bernardii, however. ) 4. Cells, often in 4’s, forming a flat coenobium with cells adjoined or not adjoined along their walls_________-_-----------—-----------------------—--— 5 5. Cells bearing spines. -____--_______- Tetrastrum 5. Cells without spines_______________---_____-______--__ Crucigenia 6. Cells cylindrical or fusiform _-_------------—---—--—--—-—-------------—-- Actinastrum 6. Cells sausage-shaped, or crescent-shaped —_.._-—---_----------- Tetrallantos [ 272 } SCENEDESMUS Meyen 1829, p.774 Colony of 2—4-8-32 ovoid, fusiform, crescent-shaped, or oblong cells lying side by side in a single series, or in a double row with the cells alternating; cell walls smooth or with spines, teeth, and ridges; chloroplast a parietal plate covering most of the cell wall and often showing a median lateral notch; 1 pyrenoid. This genus contains some species which are perhaps more widely distributed than any other fresh-water algae. Whereas a few are commonly found as euplankters, especially those which bear spines, most forms occur in tychoplankton. In favorable habitats one or two species may completely dominate the flora, and often a small artificial pool or an aquarium will be densely colored by their tremendous numbers. See Chodat (1926) and Smith (1916a) on the taxonomy and pure-culture studies of the genus. Key to the Species 1. Wall smooth, without decorations such as spines, teeth, or nid fesse 2 1. Wall decorated with spines, teeth, or 1G eS ean Pear Seen tate Ra Sy il ugh Miesgotvcelisrroundedes25em See ere Sd ad 3 2. Poles of cells narrowed, sometimes Polite ss 29 A 2 a he Sa 4 3. Cells definitely arranged in a double series... S. arcuatus 3. Cells arranged in a single series (sometimes in aniudefinitelyaltemating Series)! 122) Vee eh S. bijuga deaGellstallemnivonerplarie sheet On cielo Bete Vk ah aS 5 A Ce usmotallsin: one wplaie 2a) tb oe Ay ee Pe ee. ee 6 5. Cells fusiform, all the same shape in the colony. S. obliquus 5. Cells both fusiform and crescent-shaped in the same colony_..S. dimorphus 6. Cells adjoined alternately at their poles Guly, forming a\twasted chain! 102 8 ees ie S. Bernardii 6. Cells adjoined along their longitudinal walls, POrnaae ATCInG C= eer see ke ees meee oe ef DIS S. acuminatus 7. Cells with longitudinal ridges only, no teeth S. acutiformis 7. Cells with teeth, spines, and sometimes ridges also. 8 6: Gellsiwithsteethvorispinesyomly.< 28.07 9 &~ Cells with both teeth(or'spimes) and ridges= 9 18 9. Wall uniformly beset with very short teeth S. hystrix 9. Wall not beset with uniformly distributed teeth. 10 10. Cell wall with a longitudinal row of small teeth>"as) welllasitecthvat the poles. ets S. serratus 10. Cell wall without a longitudinal row of teeth. ia 11. Cells with only a single, blunt, papilla-like Spine ‘atythesapexvoneach celle. ee en S. incrassatulus I... Gellsi with long, shanp testh or spines 12 12. Cells with 2 or 3 sharp teeth at the poles S. denticulatus 12. Cells with long spines, not teeth alone at the poles 13 13. Spines on only the outer cells of the series 14 13. Spines on both the outer and inner cells of the series... 16 [ 273 ] 14. Cells cylindrical or ovate, adjoined along theirs errtine wl ate Tall val Sess escent ee na eR S. quadricauda 14. Cells naviculoid or subquadrate, not adjoined along theis entixe! lateral: wallsi22 3 "es ee ee ee 15 15. Cells naviculoid, attached along the middle Pe oye tdaveive keene Seb S. opoliensis 15. Cells subquadrate, lateral walls of inner cells concave; attached ionly, at the comers a eee S. perforatus 16. Spines arising from both the poles and from face of cell S. abundans 16) Spines) arising from: the polesjofthe cell only: = ee i7/ 172 Gells mavieuloid, narrowed ‘at the poles === =a. S. opoliensis 17. Cells oblong or cylindrical, the ends rounded —_______________ S. longus 18. Outer cells only bearing a long spine at each pole—-__-____ S. armatus 18. All cells bearing 2 or 4 sharp teeth at the poles —______________ S. brasiliensis Scenedesmus abundans (Kirch.) Chodat 1918, p. 77 Pl. 61, Fig. 21 Cells oblong or ovate, in a linear series of 4, the terminal cells with 1 or 2 polar spines and 2 spines on the lateral wall, the inner cells with a spine at each pole; cells 4-7 in diameter, 7-12, long. Plankter; found in several lakes; common. Mich., Wis. Scenedesmus abundans var. asymmetrica (Schroed. ) G. M. Smith 1916a, p. 468 Pl. 61, Figs. 22, 23 Cells oblong-ellipsoid, outer cells with a spine at each pole and all cells with a median spine arising perpendicularly from the lateral walls; cells 2.5-4.5 in diameter, 12-15y long. Plankter; uncommon. Wis. Scenedesmus abundans var. brevicauda G. M. Smith 1916a, p. 468 PIG, Figs: 26, 27; Pl62, Fig Cells smaller than the typical; spines shorter and fewer; cells 2.5-5u in diameter, 5-8» long; spines 1.5-3.5p long. Wis. Scenedesmus abundans var. longicauda G. M. Smith 1916a, p. 467 Pl. 62, Figs. 4,5 Cells smaller than the typical, with relatively longer spines; cells 3-6, in diameter, 7-9, long; spines 6-10, long. Wis. Scenedesmus abundans var. spicatus (West & West ) G. M. Smith 1916a, p. 468 Colony composed of 2-4 cells, the outer cells with a longitudinal series of 5-7 spines, the inner cells with 1-2 spines at the apices only; cells 4» in diameter, 7.5-9p long. Wis. [ 274 ] Scenedesmus acuminatus (Lag.) Chodat 1902, p. 211 Pl. 62, Fig. 16 Cells arranged in a curved series of 4 (rarely 8) cells strongly lunate, with sharply pointed apices, the convex walls adjoined in- wardly, the concave faces directed outward; cells 3-7 in diameter, 30-40, long. Plankter; rare. Mich., Wis. Scenedesmus acuminatus var. minor G. M. Smith 1916a, p- 436 A small variety; cells 3.5-6. in diameter, 18-28, between the apices. Wis. Scenedesmus acuminatus var. tetradesmoides G. M. Smith 1916a, p. 439 A variety with cells less strongly curved than in the typical; 2.5-4 in diameter, 11-15, long; curvature of colony varying from slight to acute. Wis. Scenedesmus acutiformis Schroeder 1897a, p. 45 Pl. 62, Figs. 6, 7 Cells arranged in a single series of 4 (2 to 8), fusiform-elliptic, with poles sharply pointed; inner cells with a single facial longitu- dinal ridge; outer cells with 2-4 longitudinal ridges; cells 7-8» in diameter, (16)-22.5y long. Plankter; found in several lakes and bogs; fairly common. Mich., Wis. Scenedesmus arcuatus Lemmermann 1899a, p. 112 Pl. 62, Fig. 8 Cells arranged to form a curved (usually double) series of 4-16 oblong-ovate individuals with lateral walls in contact along 14to 14 their length; cell wall without spines or teeth; poles of the cell broadly rounded; cells 4-8-(9) in diameter, 10-15-(17), long. Swamps, lakes. Mich., Wis. Scenedesmus arcuatus var. capitatus G. M. Smith 1918, p. 637 Pl. 62, Fig. 9 Similar to the typical form but with a short, blunt-pointed pro- jection at each pole of the cells; cells 5-11, in diameter, 11-23, long. Wis. Scenedesmus arcuatus var. platydisca G. M. Smith 1916a, p. 451 Pl. 62, Figs. 10-12 Plant composed of 8 cells arranged in a flat, rather than a curved, double series; cells oblong-elliptic, 4.5-7.54 in diameter, 8-17, long. Mich., Wis. [ 275 } Scenedesmus armatus (Chod.) G. M. Smith 1916a, p. 460 Pl. 62, Figs. 13, 14 Plant composed of 2-8 cells arranged in a single, partially alter- nating series, oblong-ellipsoid but with ends broadly rounded; terminal cells with a single, long, usually curved or unevenly bent spine at each pole; central cells with a median, incomplete longi- tudinal ridge; cells 6-8 in diameter, 9-15, long. Widely distributed and fairly common in a variety of lakes and ponds. Mich., Wis. Scenedesmus armatus var. Chodatii G. M. Smith 1916a, p. 461 A variety with more slender cells and with proportionately less of the lateral walls in contact so that the notches between the poles of adjacent cells are deeper; cells 4—5p in diameter, 11-15y long. Wis. Scenedesmus armatus var. major G. M. Smith 1920, p. 155 Pl. 62, Fig. 15; Pl. 68, Fig. 23 Cells larger than in the typical plant, 9» in diameter, 25p long; spines longer, 15y. Wis. Scenedesmus armatus var. subalternans G. M. Smith 1916a, p. 461 Colony composed of pyriform cells, subalternately arranged in two series; cells 3-5.5 in diameter, 9-12 long. Wis. Scenedesmus Bernardii G. M. Smith 1916a, p. 436 Pl. 63, Fig. 1 Colony composed of 2-8 fusiform, lunate, or sigmoid cells in a single series, but with terminal cells at an angle to the plane of arrangement of the inner cells; cells adjoined alternately by the apex of one cell to the midregion of the next in series; wall without spines or teeth; cells 3-6, in diameter, 8-17» long. Mich., Wis. Scenedesmus bijuga (Turp.) Lagerheim 1893, p. 158 Pl. 63, Figs. 2,7 Colony composed of 2-8 cells in a single (rarely alternate) flat series; cells ovate or oblong, without teeth or spines; cells 4-8» in diameter, 8-16, long. Widely distributed; often appearing as a prominent component of the littoral plankton. Mich., Wis. [ 276 ] Scenedesmus bijuga var. alternans (Reinsch) Hansgirg 1888, p. 114 Pl. 63, Figs. 3, 4 Cells ovate or elliptic, regularly arranged in 2 alternating series; cells 4-8» in diameter, 7-16, long. Widely distributed; common in the plankton of many lakes and in the tychoplankton of ponds and swamps. Mich., Wis. Scenedesmus bijuga var. flecuosus (Lemm.) Collins 1909, p. 168 A variety differing from the typical by having the cells arranged in a single series only, as many as 32 in one colony; cells broader than in the typical plant. Wis. Scenedesmus bijuga var. irregularis ( Wille) G. M. Smith 1916a, p. 448 Cells very irregularly arranged, occurring either in alternate or double series; 3.5—-6y in diameter, 7.5-10, long. Wis. Scenedesmus brasiliensis Bohlin 1897, p. 22 Pl. 63, Figs. 5,6 Colony composed of 2-8 subcylindric or ovate-ellipsoid cells arranged in a single series; apices of cells with 1-4 short teeth and with a longitudinal median ridge extending between the apices of each cell; cells (3)-5-7p in diameter, 10-22» long. Common in many lakes. Mich., Wis. Scenedesmus denticulatus Lagerheim 1882, p. 61 Pl. 63, Figs. 10, 11 Colony composed of 4 or 8 ovate cells arranged in a single series (rarely alternating); apices of cells with 1-4 short teeth; free walls of cells smooth; cells 6-10» in diameter, 8—15y long. Very common and almost always accompanying other species of Scenedesmus. Mich., Wis. Scenedesmus denticulatus var. linearis Hansgirg 1888, p. 268 Colony composed of 4 or 8 ovate cells arranged in a single, straight series, poles of the cells rounded and furnished with 2 small teeth; cells 4—5y in diameter, up to 15y long. Wis. Scenedesmus dimorphus (Turp.) Kuetzing 1833, p. 608 Pl. 63, Figs. 8, 9 Colony composed of 4 or 8 fusiform cells arranged in a single or alternating series; the inner cells with straight, sharp apices; the art | outer cells lunate, strongly curved, with acute apices; cells 3-6y in diameter, 16-22, long. Common and widely distributed in many lakes and bogs. Mich., Wis. Scenedesmus hystrix Lagerheim 1882, p. 62 Pl. 63, Fig. 12 Colony composed of 2-4-8 oblong-cylindric cells arranged in a single series; apices narrowly rounded; wall uniformly beset with short, sharp spines; cells 3-5 in diameter, 8—18p long. Rare; in plankton. Wis. Scenedesmus incrassatulus Bohlin 1897, p. 24 Pl. 63, Fig. 14 Colony composed of (2)—4-8 fusiform, subacute cells, arranged in either 1 or 2 series (alternating); median cells slightly curved; outer cells definitely curved, with the free walls strongly concave; apices of the cells with a nodular thickening; cells 5-8, in diameter, 17-24, long. Typical plant not reported from our area. Scenedesmus incrassatulus var. mononae G. M. Smith 1916a, p. 440 Pl. 63, Fig. 13 A variety differing from the typical by its smaller, more slender cells, 4.4-5y in diameter, 11-12, long. Wis. Scenedesmus longus Meyen 1829, p. 774 Pl. 63, Figs. 15, 16 Colony composed of 2—4-8 oblong-cylindric cells arranged in a single series; apices of both inner and outer cells with 1 or 2 sharp spines which are longer on the outer cells; cells 4-6u in diameter, 8—12y long. Rare in the plankton of several lakes. Mich., Wis. Scenedesmus longus var. brevispina G. M. Smith 1916a, p. 471 A variety with more slender cells than the typical and with shorter spines; cells 3-5, in diameter, 9-11p long. Wis. Scenedesmus longus var. ellipticus (West & West ) G. M. Smith 1916a, p. 472 Colony composed of 4 ellipsoid cells arranged in a single series; outer cells bearing 2 outwardly curved spines, the inner cells with a single spine; cells 5. in diameter, 12, long. Wis. [ 278 ] Scenedesmus longus var. minutus G. M. Smith 1916a, p. 471 A small variety with short spines; cells 2-3, in diameter, 8y long; spines 1.5-2, long. is. Scenedesmus longus var. Naegelii (de Bréb. ) G. M. Smith 1920, p. 156 Pl. 63, Fig. 24; Pl. 64, Fig. 1 Colony composed of 8 cylindrical cells arranged in a single series; outer cells bearing a long, curved spine at each pole; inner cells with a long spine at one pole only (rarely with no spines); cells 7-12, in diameter, 16-28, long. Plankter; in several small lakes. Mich., Wis. Scenedesmus obliquus (Turp.) Kuetzing 1833b, p. 609 Pl. 63, Fig. 17 Colony composed of 2-8 (usually 4 or 8) fusiform cells arranged in a single series; apices of cells apiculate; wall smooth; cells 4.2-9n in diameter, 14-18—( 21), long. Rare in tychoplankton of a swamp; rare in many lakes. Mich., Wis. Scenedesmus opoliensis P. Richter 1896, p.7 Pl. 63, Fig. 18 Colony composed of 2-4-8 naviculoid cells arranged in a single series, with free walls of outer cells convex, the lateral adjoined walls in contact along 1/3—2/3 of their length; apices of cells with long spines (inner cells with a spine at one pole only, or some- times without spines); cells 6—8» in diameter, 14—26, long. Rare but widely distributed. Mich., Wis. Scenedesmus opoliensis var. contacta Prescott 1944, p. 359 Pl. 63, Figs. 19, 20 Colony consisting of 4 naviculoid cells arranged in a single series, adjoined along %4 of the length of their lateral walls; spines on terminal cells either 1 or 2 at each pole, long and curved; spines on apices of inner cells short and straight; cells 6-8, in diameter, 20-24 long. Plankter; rare. Wis. Scenedesmus perforatus Lemmermann 1904, p. 159 Pl. 46, Figs. 24, 25 Cells subrectangular with convex end walls and concave lateral walls, thus forming biconvex intercellular spaces; end cells of the [ 279 } colony bearing a single long curved spine at each pole arising from the corner of the cells, the outer lateral walls of the end cells straight or umbonate; cells 3-3.5-(5) » in diameter, 10-13, long. Mich. Scenedesmus quadricauda (Turp.) de Brébisson in de Brébisson & Godey 1835, p. 66 Pl. 64, Fig. 2 Colony consisting of 2-4-8 oblong-cylindric cells usually in 1 series (sometimes in 2 alternating series); outer cells with a long curved spine at each pole; inner cells without spines or with mere papillae at the apices; cells variable-in size, 3-18. in diameter, 9-35 long. Common and widely distributed in a variety of habitats; one of the most nearly ubiquitous algal species. Mich., Wis. Scenedesmus quadricauda var. longispina (Chod. ) G. M. Smith 1916a, p. 480 Pl. 63, Fig. 22 A variety differing from the typical by the greater length of the spines; cells 3.5-5y in diameter, 8-11 long; spines 7.5-10p long. Plankter; in lakes. Mich., Wis. Scenedesmus quadricauda var. maximus West & West 1895, p. 83 Pl. 64, Figs. 3, 4 A variety differing from the typical by the larger size of cells and relatively longer spines; cells 9-11.5p in diameter, 27-36, long; spines 20-30, long. Plankter; in lakes; rare. Mich., Wis. Scenedesmus quadricauda var. parvus G. M. Smith 1916a, p. 480 Pl. 64, Fig. 6 Colony composed of 2-16 cylindrical-ovate cells arranged in a single series; outer cells with a long spine at each pole; inner cells with spineless walls; cells 46.5, in diameter, 12-17, long. Very common in many lakes and swamps. Wis. Scenedesmus quadricauda var. quadrispina (Chod. ) G. M. Smith 1916a, p. 480 Pl. 63, Fig. 21 Colony composed of 4-8 ovate cells with short spines, usually strongly recurved; cells 47.4, in diameter, 9-16p long; spines about Su long. fete but widely distributed in many lakes and ponds. Mich., Wis. [ 280 ] Scenedesmus quadricauda var. Westii G. M. Smith 1916a, p. 480 Pl. 64, Figs.7, 9 Colony composed of 4-8 ovate cells with broadly rounded apices; cells 5-8. in diameter, 10-18—(22), long; spines relatively short, often strongly reflexed. Rare, but found in the plankton of a great variety of lakes, ponds, and swampy habitats. Mich., Wis. Scenedesmus serratus (Corda) Bohlin 1901, p. 44 Pl. 64, Fig. 8 Colony composed of 4 oblong-ovate cells arranged in a single series; the outer cells with one, the inner cells with two longitudinal rows of small teeth; apices of all cells bearing 3-4 small teeth; cells 4.5-7y in diameter, 15-20, long. Plankter; in several lakes. Wis. ACTINASTRUM Lagerheim 1882, p. 70 Colonial, planktonic, composed of 4-16 truncate-fusiform or basidia-like cells, sometimes cigar-shaped with subacute poles, radiating in all planes from a common center, not inclosed by a colonial envelope; chloroplast a parietal, elongate plate covering about 14 of the wall in circumference and nearly as long as the cell; 1 pyrenoid present. Key to the Species Cells 7-10 times as long as wide, about as wide at the poles asjnithe median part of the celle. A. gracilimum Cells 3-6 times as long as wide; median part of the cell about twice as wide as the poles__.____________»____ A. Hantzschii Actinastrum gracilimum G. M. Smith 1916, p. 480 Pl. 64, Fig. 5 Cells cylindrical, with very slightly narrowed to abruptly truncate poles, forming colonies of individuals with the long axes of the cells radiating in all planes from a common center; cells 1.7—3p in diameter, 14-21 long; colonies 30—45y in diameter. Rare; in the plankton of several lakes. Mich., Wis. Actinastrum Hantzschii Lagerheim 1882, p. 70 Pl. 64, Figs. 10, 11 Cells spindle-shaped or cylindrical, narrowed toward the apices, arranged in simple or compound colonies of 4 or 8 with the long [ 281 ] axes of the cells radiating from a common center; chloroplast a parietal plate, with 1 pyrenoid; cells 3-5.6 in diameter, 12-22, long. Common in plankton. Mich., Wis. Actinastrum Hantzschii var. elongatum G. M. Smith 1918, p. 636 Pl. 65, Fig. 2 Cells cylindrical, very slightly if at all narrowed toward the apices, larger than in the typical plant; cells 4-5p in diameter, 30-35, long. Rare; in plankton. Wis. Actinastrum Hantzschii var. fluviatile Schroeder 1899, p. 20 Pl. 65, Fig. 1 A variety differing from the typical in that the cells are sharply pointed; cells 3.3-3.5y in diameter, 39-42, long. Rare in a swamp. Wis. TETRADESMUS G. M. Smith 1918, p.76 A 4-celled, free-floating colony; cells fusiform, or cylindrical, arranged in 2 planes with their longitudinal axes parallel, the adjoined walls straight, in contact throughout most of their length, the outer free wall straight or concave, the poles of the cell directed away from the center of the colony; cells in vertical view spherical, arranged in a quadrangle; chloroplast a parietal plate with 1 pyrenoid. Key to the Species Cells fusiform, attached throughout the length Ofutheinalatenal wwralllseescee cies ales ne Nera e eye ose cere T. wisconsinense Cells crescent-shaped, cylindrical, attached along only a portion of their lateral walls___________________ T. Smithii Tetradesmus Smithii Prescott 1944, p. 360 Pl. 64, Figs. 15-17 Cells slightly arcuate or crescent-shaped or subcylindrical, slightly narrowed toward the poles which are broadly rounded, in groups of 4 with their long axes parallel and with the convex walls adjoined in the mid-region only; outer free walls concave or nearly straight; cells in end view spherical, arranged in a quadrangle; chloroplast a parietal plate; cells 3.7-4y in diameter, 27-29, long. This species should be compared with Quadrigula spp. The cells are not so straight as in that genus although they have about the same proportions and are arranged in bundles of 4. Also Tetradesmus Smithii, unlike Quadrigula, has no gelatinous investment inclosing the quartets of cells. Rare; in plankton. Wis. [ 282 ] Tetradesmus wisconsinense G. M Smith 1913, p. 76 Pl. 64, Figs. 12-14 Cells fusiform arranged with their long axes parallel; cells ad- joined throughout the length of their lateral walls; outer free walls concave; poles of the cell narrowed and directed away from the center of the colony; in end view spherical, the cells arranged in a quadrangle; cells 4—-6u in diameter, 12-14.5y long. Rare; in the plankton of lakes. Wis. CRUCIGENIA Morren 1830, pp. 404, 415 Colony free-floating, consisting of a plate of 48-16 trapezoid or rhomboid cells lying in one plane about a small or large central space; chloroplast a parietal plate with 1 pyrenoid in each cell; colony inclosed by a thin, inconspicuous gelatinous envelope which often causes the families to adhere to one another and to form colonial complexes. Key to the Species 1. Opening at the center of the colony large, approximately equal: tothe, greatest dimension of ‘the cells-2 te 2 1. Opening at center of the colony small, less than theporeatest dimiensionzeta tic. cells acter 8.2 2s ee Al seal rove eee 8 2. Cells nearly hemispherical, old mother cell By AAS DES ASLS TE oe eeatooe e E El 8 SO a C. Lauterbornii 2. Cells trapezoidal; outer free walls slightly convex; old mother cell walls not persistent C. fenestrata 3. Cells triangular; opening at the center of the colony very small... 4 sate GerISH Ona Le | OT pO hy ei oKnal ioe sets PES ES Esa LE Cee hen he 5 Ap Outer tree walls; Straig@hibe fs aatte eld era 2k C. tetrapedia Are Otter eine wWallsnCOMVeN een o et Fa ee ee C. quadrata 9. Cells’ with an apiculation at the free pole C. apiculata oeCellsiwithouk au iapiculationm: 0s ot yak 28D ee a ee ee 6 6. Cells abruptly truncated at the free poles, the walls ‘thickened atthe apex 51828 We ee C. truncata 6. Cells not truncated, the wall not thickened at the apex_________________ il 7. Cells somewhat reniform, the outer free walls concave; cells “always: quadrately arranged= 25.2) at a eek C. crucifera eg CNIS OV ALC resins te oe NL ke we od SS 8 8. Cells regularly arranged in quartets or in multiples OL Quartets 15 Oj longa ees eee ee eee Ee C. rectangularis 8. Cells irregularly arranged within the colony, SOnge amt S.18 14 ce Meouier 2 tO ea a ee ee to C. irregularis Crucigenia apiculata (Lemm.) Schmidle 1901, p. 234 Pl. 65, Fig. 3 Colony composed of 4 ovate, rhomboidal or somewhat triangular cells arranged about a 4-sided opening, with 1 short, cone-shaped apiculation on the cell wall at the free outer apex, and one on the [ 283 ] lateral walls where the cells adjoin at their ‘bases’; cells 3-7 in diameter, 5-10, long; colony 6-12.51 wide, 9-18, long. Euplankter. Mich., Wis. Crucigenia crucifera (Wolle) Collins 1909, p. 170 Pl. 65, Fig. 4 Colony consisting of 4-sided cells arranged about a central square opening, the outer free walls longer and concave, the outer free angles of the cells rounded, the lateral adjoined walls straight and converging inward where they adjoin other cells, the inner walls about the central opening forming a short, straight side; multiple colonies resulting from the adherence of quartets of cells by per- sisting mother cell walls; cells 3.5-5yu in diameter, 5-7 long; colony 9-11, wide, 14-16, long. Plankter. Mich., Wis. Crucigenia fenestrata Schmidle 1901, p. 234 Pl. 65, Fig. 5 Colony consisting of 4 trapezoidal cells arranged about a square opening, the outer free wall longest and convex, the free angles sharply rounded; lateral and inner (the shortest) walls straight; cells 3-5 in diameter, 5-13, long; colony 8-14y wide, frequently adjoined in closely arranged association to form multiple colonies. Rare; found in the euplankton of a few lakes. Mich., Wis. Crucigenia irregularis Wille 1898, p. 302 Pl. 65, Fig. 6 Colony free-floating, consisting of 4, or multiples of 4 ovate cells not definitely arranged about a central space as in other species of the genus and not in quadrangular formation, with both lateral and apical walls in contact; chloroplasts broad parietal plates or discs, as many as 4 in a cell; pyrenoid sometimes absent; cells 5-9 in diameter, 8-14» long. This is the most frequently seeu species of Crucigenia in our collections. It should be compared with C. rectangularis (Naeg. ) Gay which also has ovate cells but in which the cells have a regular arrangement about a central space. Common in a large number of lakes and ponds. Mich., Wis. Crucigenia Lauterbornii Schmidle 1901, p. 234 Pl. 65, Fig. 11 Colony free-floating, consisting of 4 subspherical cells arranged in 2 opposite pairs about a large square space bounded by the flat, [ 284 ] inner walls of the cells; cells in contact only at their inner corners; 1 chloroplast, parietal along the outer convex wall; pyrenoid present; cells 4.5-9 in diameter, 8-15, long; quartets of cells adjoined in multiples by remains of old mother cell walls. Rare; in the plankton of several lakes. Wis. Crucigenia quadrata Morren 1830, pp. 415, 426 Pl. 65, Fig.10 Colony free-floating, consisting of a circular plate of 4 triangular cells, cruciately arranged about a small central space, the outer free wall of the cells broadly convex, the lateral walls straight, adjoined throughout their length with neighboring cells and converging to- ward the center of the colony; walls sometimes with knob-like projections; chloroplasts parietal discs, as many as 4 in a cell; pyrenoids not always present; cells 2.5-6. in diameter, 3.7, long; multiple quadrate colonies formed by the close arrangement of component quartets. Smith (1920, p. 147) considers Staurogenia multiseta var. punctata Schmidle and Crucigenia triangularis (Chod.) Schmidle to be synonymous with this species. Plankter; found in a large number of lakes in northern counties. Mich., Wis. Crucigenia rectangularis (A. Braun) Gay 1891, p. 100 Pl. 65, Figs. 7,8 Colony free-floating, consisting of ovate or oblong cells, very regularly arranged about a rectangular central space in 2 pairs, with the apices adjoining; chloroplasts 1-4, parietal discs, with a pyrenoid in each; cells 4-7 in diameter, 5-10,» long. This species should be compared with C. irregularis Wille. Common in both eu- and tychoplankton of a large number of lakes. Mich., Wis. Crucigenia tetrapedia (Kirch.) West & West 1902, p. 62 PliGa;, Hig. 9; Fl..66, Fig.) Colony free-floating, consisting of 4 triangular cells cruciately arranged about a minute central space; outer free wall and lateral walls straight, the angles acutely rounded; chloroplast a parietal plate with a single pyrenoid; cells 4.5-9 in diameter, frequently forming a rectangular plate of 16 cells (4 quartets). Common in a small lake. Wis. [ 285 ] Crucigenia truncata G. M. Smith 1920, p. 146 Pl. 66, Fig.2 Colony free-floating, consisting of 4 ovate cells arranged about a central, rectangular space, with lateral walls of each pair of cells adjoining and with apical walls in contact at the corners, the outer free walls thick and truncate, straight; chloroplasts 1-4, parietal discs; pyrenoids absent; quartets of cells adjoined to form compound colonies by the adherence of old mother cell walls; cells 4-6, in diameter; colonies up to 50 wide, 75y long. Rare in the plankton of several lakes. Wis. TETRASTRUM Chodat 1895a, p. 114 Plant a free-floating colony of 4 triangular, cruciately arranged cells, inner faces straight and adjoined to form a rectangular plate, outer free wall convex and beset with 3 or 4 short setae; colony inclosed by a thin gelatinous matrix; chloroplasts 1-4 in each cell, parietal discs with pyrenoids sometimes absent. This plant should be compared with Crucigenia, a genus with which it has much in common. Some species of Crucigenia in the past have been assigned to Tetrastrum. The latter genus is character- ized by the setae, by its possession of a definite colonial investment, and by its failure to form compound colonies. Key to the Species Outer faces of cells with short, knob-like projections —.______. T. punctatum Outer faces of cells with long, hair-like setae _________- T. staurogeniaeforme Tetrastrum punctatum (Schmidle) Ahlstrom & Tiffany 1934, p. 504 Colony of 4 angular, or somewhat triangular cells, broadly convex on their outer free walls, arranged about a very small central space; walls furnished with several coarse knob-like projections; chloro- plast parietal and plate-like, with a single pyrenoid; cells 8-12» in diameter. Uncommon; in plankton. Mich., Wis. Tetrastrum staurogeniaeforme (Schroeder ) Lemmermann 1900d, p. 95 Pl'66; Fig.* 3 A colony of 4 triangular cells, cruciately arranged about a small rectangular space; lateral margins of the cells straight and adjoined, the outer free walls convex and furnished with as many as 6 fine, hair-like setae; chloroplasts 1-4 parietal discs, sometimes containing [ 286 ] pyrenoids; cells 3-6, in diameter; colony 7-15» wide without setae, which are 4-8, long. This species should be compared with Crucigenia quadrata. Rare in the plankton of several lakes. Mich., Wis. TETRALLANTOS Teiling 1916, p. 62 A colony of 4 crescent-shaped or sausage-shaped cells which are bluntly rounded at their apices and inclosed by a colonial mucilage, with clusters of daughter cells often held in approximation by old mother cell wall fragments; cells in 2 pairs and in 2 planes, 1 pair facing each other and in contact at their poles, the other pair in a longitudinal plane vertical to these and so arranged that each member has 1 pole at the point of contact of the poles of the other pair; chloroplast a parietal plate with 1 pyrenoid. Tetrallantos Lagerheimii Teiling 1916, p. 62 Pl. 66, Figs. 4-6 Characteristics as described for the genus; cells 4-8» in diameter, 10-13 long. This rather unusual plant is rare in the United States, apparently having been found only in Wisconsin, Massachusetts, and Mississippi. Rare; in the plankton of soft water lakes and small ponds. Wis. MICRACTINIUM Fresenius 1858, p. 236 Free-floating, one-celled or in colonies of tetrahedrally or pyramid- ally arranged spherical or ovate cells (sometimes in 1 plane); walls beset with 1-7 long, needle-like setae; 1 parietal, cup-shaped chloroplast containing a single pyrenoid. Korschikov (1937) reports observation of sexual reproduction in this genus. Key to the Species Gellsspherical; setae/20=S5p longa. 1 hee ee M. pusillum Gellsiovatesssetac (2040 n long oe fe te Ta kN M. quadrisetum Micractinium pusillum Fresenius 1858, p. 236 Pl. 66, Fig. 8 A free-floating colony of 4-16 spherical cells arranged in a pyramid or in a square, groups of 4 in association with other similar groups; free walls beset with 1-5 finely tapering setae; chloroplast a parietal cup with 1 pyrenoid; cells 3-7 in diameter without setae; setae 20-35, long. Rare in the plankton of many lakes, mostly soft water habitats. Mich., Wis. [ 287 ] Micractinium pusillum var. elegans G. M. Smith 1918, p. 631 Pl. 66, Fig. 7 A variety differing from the typical by having more numerous and longer setae on the free walls of the cells; setae 5-7 in number. Rare; in plankton. Wis. Micractinium quadrisetum (Lemm.) G. M. Smith 1916, p. 479 Pl. 68, Fig. 1 A free-floating colony of 4 ovate cells, adjoined to other groups of 4 about a central rectangular space; wall with 1-4 very long, finely tapering setae; chloroplast a parietal cup with 1 pyrenoid; cells 4~-7p in diameter, 8-10, long; setae 23-40, long. Rare; in the plankton of lakes. Mich., Wis. ORDER SIPHONALES In this order the thallus is a coenocytic tube, more or less branched and usually showing a basal-distal differentiation. In marine forms the thallus becomes very elaborate and complex; in the fresh-water genera the vegetative thallus is simplified, although sexual repro- duction is of an advanced type. There are no cross walls except where sex organs or zoospores are cut off, although in Dichotomosiphon there are frequent constrictions of the filament. There are numerous ovate chloroplasts peripherally arranged in a layer of cytoplasm along the wall, the center of the tube being vacuolate. There are no pyrenoids, but starch is stored in Dichotomosiphon, and either starch or oil may accumulate in Phyllosiphon and Vaucheria.* Asexual reproduction is accomplished by zoospores or aplano- spores. In sexual reproduction a high type of heterogamy is involved. Enlarged oogonia, each with a single egg, are cut off by a wall from the vegetative filament, usually near tubular antheridia which produce large numbers of small biflagellate antherozoids. Fertiliza- tion is effected through a terminal pore in the wall of the oogonium. Key to the Families Plants: endophytic. = 25.23 oe Se ay eet PHYLLOSIPHONACEAE Plants free-living, either aquatic or subaerial VAUCHERIACEA® FAMILY PHYLLOSIPHONACEAE In this family the thallus is a much contorted tubular or vesicular coenocyte which is either endozoic or (in our specimens) endophytic. The plants inhabit the tissues of the Araceae, especially in tropical and subtropical climates. There is but a single genus in our region. *Now considered a member of the Chrysophyta. [ 288 ] PHYLLOSIPHON Kihn 1878, p. 24 This genus is parasitic in the tissues of the common Jack-in-the- pulpit, Arisaema triphyllum (L.) Schott. The thallus consists of a much twisted and closely compacted coenocytic tubular filament with numerous oval chloroplasts and nuclei. The alga brings about the disintegration of the host tissues and a destruction of the chlorophyll so that large yellow patches develop. Food reserve is in the form of either starch or oil. The only known method of reproduction is by the formation of numerous aplanospores in the tube which, upon being liberated, generate new coenocytic filaments directly. Phyllosiphon Arisari Kiihn 1878, p. 24 Pl. 69, Figs. 1-3 Characters as described for the genus; tubes dichotomously branched, ramifying among the tissues of the host plant and producing discolored areas; tubes 25-35, in diameter, 60» in diameter during aplanospore production. On blades and stalks of Jack-in-the-pulpit. Wis. (Swingle). FAMILY VAUCHERIACEAE Thallus long, much-branched, coenocytic tubes, sometimes pos- sessing horizontal, downwardly directed, and vertical sex-organ- bearing branches; chloroplasts numerous ovate or circular discs embedded in a thin sheet of cytoplasm along the wall and about large vacuolated central regions; pyrenoids lacking; reserve food either oil or (less often) starch; reproduction by large multiflagellate zoospores cut off from the ends of branches, by akinetes, or by eggs and antherozoids, the gametes being produced in special sex organs. Key to the Genera Regularly branched dichotomously and frequently constricted; sex organs terminal -2) 2) 22s he Dichotomosiphon Irregularly branched (sometimes sparsely so), not constricted; sex organs lateral on the main filament are (eearmimell Gyn leiwereall [sree Vaucheria DICHOTOMOSIPHON Ernst 1902, p. 115 A multinucleate siphon, forming attached, felt-like masses on the bottom of aquatic habitats, or rarely subaerial on damp soil; branch- ing usually dichotomous with frequent constrictions at the base of the branches; chloroplasts numerous small discs; pyrenoids lacking; sexual reproduction oogamous, the sex organs borne in corymb-like [ 289 ] clusters at the ends of branches, the oogonia usually solitary glo- bose; antheridia 1 to several in the cluster, formed at the tip of the branch, becoming cut off by a septation, producing numerous motile antherozoids. Large akinetes are common. There is but one species in this genus. Dichotomosiphon tuberosus (A. Braun) Ernst 1902, p. 115 Pl. 68, Figs. 6,7 Thallus a dichotomously branched tube with constrictions at the base of the branches and with cross walls only where reproductive structures are cut off; forming felt-like or cushion-like mats in the silt of lake bottoms, and consisting of horizontal, downwardly projecting, and erect, sex-organ-bearing branches; much enlarged, elongate, subcylindric or globose akinetes frequent; sex organs monoecious, located at the ends of strongly recurved branchlets which form corymb-like clusters at the ends of vegetative filaments; usually 1 spherical oogonium and several cylindrical antheridia present; the oospores globular, becoming yellow at maturity and easily seen with the unaided eye, oospore wall 3-layered; vegetative siphons 50-100, in diameter; oogonia 250-300» in diameter; oospore nearly the same size as the oogonium; antheridia 35—50u in diameter, 2-4 times the diameter in length. This plant seems to grow only in lakes with a rich organic silt. The thallus is often nearly buried in loose bottom deposits with only the tips of vertical branches and the sex organs emerging. In Wisconsin the plant has not been collected except from hard water or eutrophic lakes. In Michigan it is common at depths up to 16 meters, but in such habitats it appears to reproduce only by akinetes, sex organs being formed when the plant grows at 2 meters or less. This may be related to water temperature. Like Vaucheria, Dichotomosiphon forms a habitat for an association of microfauna such as Rotifera, Cladocera, and many protozoa. From several lakes, mostly from silty bottoms. Mich., Wis. VAUCHERIA De Candolle 1805, p. 61* Thallus subaerial or aquatic, a much and irregularly branched siphonous coenocyte without cross walls except where reproductive structures are cut off; filaments often compactly interwoven (espe- cially in terrestrial species) to form a felt-like expansion, with colorless rhizoids when attached, or forming entangled clots of coarse threads when floating; branches arising laterally or dichoto- mously, nearly as large as the main filament and tapering slightly to broadly rounded tips; chloroplasts numerous ovate discs without *See footnote, p. 288. [ 290 ] pyrenoids; asexual reproduction by large globose, multiflagellate zoospores cut off singly at the ends of clavate branches; thick-walled akinetes at the ends of branches, or in the tubes of some species; sexual reproduction oogamous; oogonia globose or ovate, sessile, on pedicels, or on long stalks, containing a single egg which may completely fill the oogonium; antheridia on the same or different filaments, clavate, cylindrical, or subcylindrical, coiled or straight, usually reflexed with the terminal opening directed toward the oogonium, borne near the oogonia or at the end of a series, producing many biflagellate, ovoid to fusiform antherozoids; oospores with thick walls, sometimes completely filling the oogonia and the same shape. Key to the Species i Oogonia: 262 —289n 1m: diameter 2a ee V. Nicholsii He @n Conta SAN er se kere cal AN eS ee Ae eats Tastee Lag 2 2. Oovonia sessile’ on the main filament = = 8 eee 3 2. Oogonia: on a ‘pedicel or ‘ona lateral ‘branch. 2 5 3. Oogonia obliquely ovate, large, up to 160 high andy 220), dongee wall) Gut tinick: 2.) ithe ket V. pachydermum 83. Oogonia more nearly erect, smaller; wall not thick __--________ 4 4. Oogonia erect, the pore vertically directed _..__.________. V. orthocarpa 4, Oogonia with the pore directed obliquely upward_______________ V. sessilis 5. Oogonia on a short pedicel, sometimes nearly sessile_.____-_______-____ 6 5. Oogonia at the end of a long or short lateral branch, stalked. 10 6. Oospores not filling the oogonia; oogonia usually In"pairss the pores directed oppositely. © ss Te V. aversa 6. Oospores filling the oogonia; arranged otherwise —.______-__-__-__ vi 7. Pedicel very short, scarcely evident; oogonia broadly ovate, the pore nearly erect _____--..--_-----—-_________.--. V. sessilis 7. Pedicel evident; oogonia narrowly ovate or ellipsoid, the pore oblique or more nearly horizontal -_.__.__________----_-_---------------- 8 8. Oogonia in pairs, or several on a short pedicel, thewantheridiumimbebweensa ees = = sue eek eee ee ie V. geminata 8. Oogonia arising singly, near the antheridium________________ 9 9. Oogonia 80-150. in diameter, the pore directed horizontally or obliquely downward © __--------------- *V. ornithocephala 9. Oogonia 60-65. in diameter; pore directed obliquely upward_V. polysperma 10. Oogonia 2 to several on the end of a lateral branch arialllimeter Or mnone’ Int Wen cthizce te Sek snot ot ee er eke V. longipes 10: Oogonia solitary, ona. much) shorter branch 2-2 pe 11 11. Oogonia 60-103, in diameter, 85-211, long, without a pedicel from the branch, arising near the base of the antheridia _______ V. terrestris 11. Oogonia averaging smaller, 60-75 in diameter, 75-90 long, with a pedicel, placing it well above the associated antheridium —___- V. hamata Vaucheria aversa Hassall 1843, p. 429 Pl. 66, Figs. 9, 10 Coarse filaments, freely branched and readily collapsing upon being handled, 65-100» in diameter; oogonia usually in pairs or [ 291 ] several in a series on very short pedicels, mostly sessile, ovoid to subglobose, opening by an oblique pore in a narrow beak which faces in an opposite direction from the neighboring oogonium, 100-125, in diameter, 180-250, long; antheridia subcylindric, strong- ly recurved, one on each side of a pair or series of oogonia; oospores globose, with a 3-layered membrane, 80-120, in diameter, not filling the oogonium. Forming a soft, felt-like mat in spring seeps and on moist shady banks of streams, etc. Wis. Vaucheria geminata (Vauch.) De Candolle 1805, p. 62 Fl 68, Pigs: 223 Aquatic or on very moist soil; filaments coarse and freely branched, 80-100 in diameter; oogonia in pairs, ovate to subglobose, borne laterally near the end of a short stipitate branch of the main axis, with 1 antheridium circinate or strongly reflected; oogonia with pores directed vertically, 60-80, in diameter, 70-90 long; oospores with thick, 3-layered membranes, completely filling and the same shape as the oogonia. Forming floating, tangled mats in marshes and cut-oi ; from lakes protected from wave action; in ditches of shallow water Mich., Wis. Vaucheria geminata var. depressa Transeau 197, .228 A variety differing from the typical by having the pedicels of the oogonia longer than in the typical, arising from a saort lateral branch and curved so that the oogonia are in contact with the main filament. Mich. Vaucheria hamata (Vauch.) De Candolle 1805, p. 63 Filaments rather slender; monoecious; oogonia solitary, or rarely 2 together, ovate to somewhat lunate, with the inner or lower margin somewhat concave, borne on a pedicel at the end of a lateral branch from the main axis, 60-75, in diameter, 75-90, long; antheridium tubular, circinate, arising from near the base of the oogonium pedicel; oospore with a 4-layered membrane, completely filling the oogonium, containing a dark granular spot. Floating, tangled mats in quiet water. Mich., Wis. Vaucheria longipes Collins 1907, p. 201 Pl. 67, Fig. 5 Filaments rather coarse, 80-90» in diameter; monoecious; sex organs on a long (1-4 mm.) lateral branch, 30-40, in diameter; the [ 292 ] antheridium distinctly circinate, terminal on the branch; oogonia usually 3 (2-4), ovoid, somewhat oblique on rather long stalks (up to 1500.) arising from just below the antheridium, 35-40, in diameter, 70-85, long. In pooled streams and quiet water of lakes. Wis. Vaucheria Nicholsii Brown 1937, p. 283 Pl. 67, Fig. 10 Filaments very coarse, 112-120, in diameter; monoecious; oogonia globose, sessile, the opening vertical, 262-289, in diameter; oospore the same shape as and filling the oogonium (except the beak), yellow-brown; antheridia sessile, arising from all sides of the main filament near the oogonium and recurved so as to lie parallel with the filament and opening toward the oogonium, 39-50p wide, 115-123, long. Shore of Douglas Lake, Michigan. Vaucheria orthocarpa Reinsch 1887, p. 191 BW6(, Hig Filaments slender to moderately coarse, 77-110» in diameter; monoecious; oogonia sessile, ovoid, erect with the opening vertical; oospore ovate, completely filling the oogonium, the wall thick, 50-65 in diameter, 65-90» long; antheridia sessile, arising near the oogonia, distinctly coiled, with the opening directed toward the oogonium. Mich. Vaucheria pachyderma Walz 1866, p. 146 Pl. 67, Fig. 2 Filaments variable, slender or stout, 40-123 in diameter; monoe- cious; oogonia mostly solitary, globular or transversely ellipsoid, the opening horizontal, or downwardly oblique, the wall thick, up to 6u, with discolored spots, 69-160» high, 69-220, long; oospore filling the oogonium, 145, in diameter, 180, long, with a thick wall; antheridium erect beside the oogonium, hooked at the apex. Mich. Vaucheria polysperma Hassall 1843, Pl. 6, Fig. 6 Pl. 67, Fig. 13 Filaments very slender, 15-33» in diameter; monoecious; oogonia in a series of 3-5, each on a short pedicel, ovate, opening upwardly oblique, 60-65, in diameter; oospores globose, filling the oogonium in width only, 44-60.5 in diameter; antheridia cylindrical, sessile on a short pedicel, strongly reflexed and opening toward the oogonia. Mich. [ 293 ] Vaucheria sessilis (Vauch.) De Candolle 1805, p. 63 PIGS) Higa5 Aquatic or terrestrial; filaments somewhat slender, 50-58» in diameter, with irregular branching; monoecious; oogonia usually in pairs, ovoid to subglobose with the pore in a short beak and directed obliquely upward, 70-85» in diameter, as much as 100p long; antheridia on a short pedicel between 2 oogonia, either straight or circinate, but usually with the opening directed toward the pore of an oogonium, about 25p in diameter; oospore with a 3-layered membrane, filling the oogonium. A common species but infrequently found in our collections; forming a felt-like mat on submerged rocks and on sandy bottoms of springs; on rocky outcrops where there is trickling water. Mich., Wis. Vaucheria sessilis fa. clavata (Klebs) Heering 1921, p. 88 Pl. 67, Figs. 3, 4 Filaments stouter than in the typical, 77-110, in diameter; oogonia broadly ovate with the beak directed vertically; oospore 49.5-66.5p in diameter, 66-88.5, long. Mich. Vaucheria terrestris (Vauch.) De Candolle 1805, p. 62 Pl. 68, Fig. 4 Either aquatic or terrestrial, usually forming floating clots; fila- ments rather slender, 50-80 in diameter, branching dichotomous, or at right angles to the main filament (as in the case of the relatively long branches which bear the sex organs ); monoecious; oogonia subglobose to ovoid, at the end of a slightly bent stalk, with the pore directed downward, exceeding the antheridium and appearing to be terminal on the branch, 60-103 in diameter, 85-211, long; antheridia strongly circinate, 15-20 in diameter, terminating the branch but appearing to arise beneath the oogonium; oospore with a thick, 4-layered membrane, completely filling the oogonium which falls with the oospore. Floating in hard or soft water lakes and small ponds, becoming mature and fruiting abundantly at low temperatures. This species is also found on moist soil, especially in well-shaded habitats. Mich., Wis. ORDER ZYGNEMATALES Except for the desmid families in which there are unicellular genera (See Appendix) plants in this order are unbranched filaments without basal-distal differentiation. Rarely, incidental rhizoidal branches may be formed where filaments come in contact [ 294 ] with substrates. The cells are long or short cylinders, but in some species the cells become inflated during the reproductive process (conjugation ). The cell wall has 1 or 2 layers of firm cellulose and an outer pectose layer of varying thickness and consistency. The mucilaginous sheath present in most forms is responsible for the fact that these plants very seldom become hosts for epiphytes although frequently parasitized by Lagenidium and Myzocytium (Phycomycetes). The end walls of the cells are separated by a middle lamella and may be either plane or characteristically infolded (replicate). One of the most characteristic features of this order is the relatively large size of the chloroplasts, usually 1 or 2 in each cell, although in Spirogyra there may be several (up to 16). Pyrenoids in the chloroplasts are large and conspicuous, but in Mougeotiopsis pyrenoids are lacking. The chloroplasts may be axial plates, stellate masses or cushions, or parietal spiral ribbons. In asex- ual reproduction aplanospores and akinetes are sometimes formed. It is in sexual reproduction that plants in this order show their most distinctive characteristics. Either all or part of the vegetative cell content serves as a gamete, union being achieved by one or both gametes passing through a tube which forms between the cells of two filaments (scalariform conjugation) or between cells of the same filament (lateral conjugation). In a few species, filaments become adjoined or are juxtaposed, and gametic union is achieved without the use of tubes. The resulting zygospore has a wall which is usually 3-layered and thick. It may be smooth or the outer layers may be decorated with scrobiculations, pits, or reticulations, features which are specific and of taxonomic importance. The gametangial cells after conjugation may be empty or may become filled with pectic compounds which are usually deposited in layers. Motile reproductive cells do not occur. This, together with other fundamental details of the life history, behavior of the germinating zygospore, etc., set the Zygnematales well apart from other orders of the Chlorophyta, so that in some systems of classification they have been placed outside the Chlorophyceae. Of the 3 families which comprise this order (Zygnemataceae, Me- sotaeniaceae, Desmidiaceae*) only the first is considered in this book. FAMILY ZYGNEMATACEAE Characteristics as described for the order; cells short- or long- cylindric with plane or folded end walls, usually unbranched and without basal-distal differentiation; chloroplasts few, large, and, except for one genus, with conspicuous pyrenoids. *See appendix for desmid genera. [ 295 ] Besides conjugation, described above, akinetes (thick-walled rest- ing cells formed by modification of vegetative cells) or partheno- spores (aplanospores ) may occur. The latter are thick-walled, zygo- spore-like bodies formed within cells independent of conjugation. Reproductive material often can be identified in the field, espec- ially in Spirogyra, Mougeotia, and Zygnema, by the foamy, brownish or ‘dirty’ appearance of the plant masses. In many forms conjugation regularly occurs in surface mats of filaments, each species fruiting in its own season. Key to the Genera 1. Cells with 2 broad, disc-like chloroplasts, mostly axial but in part parietal; cell sap deep purples (rarely, colorless) = * Pleurodiscus 1. Cells with other types of chloroplasts; cell sap colorless (but lilac or purplish-brown in Mougeotia Capucing ee 2 to Chloroplasts parietal ribbons (usually with laciniate or crenate margins ), spiral (rarely nearly straight), with several to many pyrenoids in a Siig lesserics == Spirogyra (including Sirogonium ) 2. Chloroplasts axial, shaped otherwise, broad bands, stellate bodies, elongate pads, or axial polster (cushion-shaped) bodies == 3 3. Chloroplasts axial plates or bands, broad and filling the width of the cell in some; pyrenoids none, or 2 to many, in 1 row or Scattered ae 4 3. Chloroplasts (usually 2) axial, star-shaped or pad-like bodies aS PE Ys 4. Chloroplasts without pyrenoids_____--------------_--------- Mougeotiopsis 4, Chloroplasts with pyrenoids._________----------------——-------------- 5 5. Conjugating cells formed by a portion of the vegetative cell cut off from one end —-_________-- *Temnogametum 5. Conjugating cells involving the entire vegetative cell 6 6. Conjugating cells becoming filled with pectic substances —___- Debarya 6. Conjugating cells not becoming filled with pectic substances, often containing granular residues ____--------------------------------— Mougeotia 7. Chloroplasts 2 central, polsterform bodies (without, or with very short, radiating processes); cytoplasmic granular material left in conjugating cells and in ‘sporangia + -.------____-------------- Zygogonium 7. Chloroplasts 2 star-shaped bodies in each cell (radiating processes long) =. ——--=--=-——- =n 8 8. Conjugating cells becoming filled with pectic substances; zygospores always formed in the tube, spheroidal or mostly quadrate, flattened or polsterform in side view ——----- Zygnemopsis 8. Conjugating cells not becoming filled with pectic substances; zygospores formed in the tube or in one of the gametangia, globose, ovate, or somewhat cylindric_________— Zygnema DEBARYA (Wittr.) Transeau 1934, p. 203 Filaments of slender, cylindrical cells; chloroplast a narrow axial plate containing 2-8 pyrenoids (these sometimes increasing in number prior to conjugation); conjugation scalariform by pro- tuberances from both gametangia; zygospores variable in shape, [ 296 ] ovate, quadrangular-ovate, or spheroidal, formed between the gametangia, the median wall yellow, brown, or blue, smooth or variously ornamented; gametangia becoming filled with pectic substances but without residues of cytoplasmic granules; reproduc- tion also by aplanospores and akinetes. This genus is so much like Mougeotia in its vegetative expression that identification cannot be made unless reproductive stages are at hand. Key to the Species Zygospores lenticular, with 3 transverse ridges, 30—48u in diameter, 42-72 long. D. glyptosperma Zygospores compressed-globose, median spore wall tricarinate, 50-54 in diameter, 52-654 long D. Ackleyana Debarya Ackleyana Transeau 1944, p. 244 Vegetative cells 12-15, in diameter, 90-140, long; chloroplast an axial ribbon with 8 pyrenoids; zygospores compressed-globose or ovate, median spore wall with 3 ridges, the lateral ones ruffled and with transverse corrugations between the ridges, middle keel 10 wide and radially striated, polar walls finely pitted, 50-54 in diameter, 52-65, long. Douglas Lake, Michigan. Debarya glyptosperma (DeBary ) Wittrock 1872, p. 35 Vegetative cells 9-16 in diameter, 50-200, long; chloroplast an axial plate with several pyrenoids; zygospores lenticular or compressed-ovate, median spore wall with 3 ridges which extend as projections at the poles, the ridges interconnected by transverse striations, 30-48, in diameter, 42-72, long. Douglas Lake, Michigan. MOUGEOTIA (C. A. Agardh) Wittrock 1872, p. 35 Unattached filaments of cylindrical cells without basal-distal differentiation (rarely with lateral anchoring rhizoidal branches near one end of the filament), forming entangled cottony masses, floating or caught among aquatic plants, sometimes attached and epiphytic on submerged culms of Scirpus, etc. Chloroplast occasion- ally rod-like, usually a broad axial plate, sometimes 2 plates connected by a bridge; with either an axial row of pyrenoids or with pyrenoids scattered over the surface; sometimes twisted in the midregion of the cell. Conjugation usually scalariform, the zygospore formed in the tube between the gametangia; the zygo- spore and tube sometimes enlarged so as to divide the gametangia, [ 297 ] giving the sporangium the appearance of being bounded by as many as 4 cells. Zygospore wall smooth or variously decorated; with residues in the gametangial cells outside the zygospore. bo e bo . Zygospores . Zygospores The genus should be compared with Debarya. Key to the Species . Reproduction by aplanospores only; conjugation and zygospores unknown M. ventricosa . Reproduction by conjugation; aplanospores present or absent................ . Zygospores formed in the tube, but extending into and dividing one. of the Gametaneia Giga aosce seer eet ea ecae 3 . Zygospores formed wholly in the tube, or extending into both gametangia ....... By sel Rae ATI Ln Te rok Ne ct WAY ADe ee exe 6 . Zygospores drum-shaped (short-cylindric) 0.0.0.0... M. varians D0 19 OID D TTT A G9 9 Zygospores some other shape ................:ccccceecee ete ete ee ec eeer ene Zygospores globose or triangular-ovate, 30—40u in diameter M. floridana Zygospores ovate to subglobose, 40—45m in diameter........ M. sphaerocarpa Zygospores formed wholly in the conjugating Guile pate ees ite eee Zygospores extending into and dividing both gametangia...................... 22 Zig @aspore + Wall psmnOOtlay. cet ee cases obeges es cere coe sane epe aed brane ne nee ses eareee nee 8 Zygospore wall (median or outer layer) decorated... 17 . Vegetative cells 20—40u in diameter... etree 9 . Vegetative cells 204 in diameter or less............0.0..1:c eee 13 pe Spore: wall Woltpet estes cec eine tance ces tence cage nec ata sents oa alitacseceearsee M. maltae P Spore, wall’ ‘rowan c.cc.g te seiko ie acarte cde cene nee taeeei ek eee oneemes ase 10 10. Zygospores cylindric-ovate in front VieW.............00c M. laetevirens 10. Zygospores some other shape ...............0c:ccccec settee tees ee te cseeeeeneeaeaeeeneey 11 11. Zygospores ovate, 40—48u in diameter.............0..0:: cee M. Hirnii 11. Zygospores some other shape .................:::c:ccesessseece teen ener 12 . Zygospores diameter quadrately ovoid to subglobose, 30—40u in 12. Zygospores ovate-globose, (23)—30—31u in diameter.............. M. scalaris 13. Zygospores globose) —.........-.... CAP eed) ME He UTR OA As kar he OO Mat toate ete 14 13. Zygospores quadrate-globose or rhomboid .................::: ese 16 14. Vegetative cells 6—12u in diameter..................0:c: eee M. parvula 14. Vegetative cells larger ....... ES Be tne cree Chale Tr nent 1S 15. Spore wall blue; vegetative cells 17—20—(22)u in diameter... M. maltae . Spore wall brown; vegetative cells 12—18u in diameter . Zygospores quadrate-globose or rhomboidal; . Vegetative cells 8—16u in diameter.................0:: ee . Spore wall brown, coarsely punctate M. recurva aplanospores oblique-ovate . Zygospores sexangular- or octangular-globose; aplanospores globose . Vegetative cells (14)—18—20m in diameter. ...........0.... ee 18 . Zygospore wall punctate ................:cccee ree sceees tsetse retenenesenenenaneneneuttectoness 19 . Zygospore wall scrobiculate....................::ecsseceeetee eset tenenteatneneteneeceeenes 21 . Spore wall blue, finely punctate ...............00: ce M. cyanea [ 298 ] 20. 20. 21. 21. 22. 22. 23. 23. 24. 24. 25. 25. 26. 26. 27. 27. 28. 28. 29. 29. 30. 30. 31. 31. Vegetative cells 18—23u in diameter; PY COSPOLES* PIODOSE! LO) \OVALE deste a eee nes ccs Soka nse p dass stion: M. micropora Vegetative cells 24—29, in diameter; zygospores ovate-ellipsoid, with flattened ends ................. fd wee A kee ty Aled ad eae ee eens M. pulchella Zygospores 20—30—(36)u in diameter; ovate to ‘broadly ellipsoid: pyrenoids an, J rOW.-..2.25.-.<:csee:savisse.tas beens M. laevis Zygospores 35—41y in diameter, ovate to subglobose; ‘pyrenoids ‘scattered 0.2... i020 iecese sate esseestedetetneie ties M. robusta PESOS POLE Y NV lA ISTMO OEM: on. te. ok: Sth cagy her tes, be Sac wise se Meri Cade 23 Zyeospore wall decorated. :2...5 2.05. csexc.etsnsae et ads oe Oe AT We 29 Wesetative cells (4 —Spe im \diatmeter .22 acto cca soe ee eae estas se seen os secures ere 24 Vegetative cells (8)—9—24u in diameter...................0:c cette 26 Vesetativecells’ 4—5e in diameter: 7.0). f. uc se5s SH hee asnnadesss 25 WVeoetative cells 6—8m in diameter. 1c0j.1c25.-:-ceceeccees ns ne ee M. viridis Zygospores irregularly quadrate, the angles extended ........... M. americana Zygospores cruciate-quadrate, with concave WHAT SINS «the, OMENS | LOUNGE {0c rsync. cvelcosec cece st toes ....M. elegantula Zygospores globose, or angular-globose...............0....0.:0:cee M. calcarea ZYGOSpPOres: Ovate, (OL UAGrAMmUlar 5G ck ec sates ateh ee erase techn consent a7 Zygospores ovate to subglobose; vegetative Gals MO=OAbine Shan GUETTATE a nposatenndlt meee: onbeoncscbaaneecocienmbtbere M. sphaerocarpa Zygospores quadrate; vegetative cells 8—19—(21)u in diameter ......... 28 Wallon WoUEplisinee eee een see ede en a BN ana ences M. capucina Gellscsapenotypurplshis inet ee tee Ue eee NT Sl ohtitec deance M. virescens Vegetative cells (8)—13—16u in diameter; Nala GlarmeOSPOLe . PIMCtALG gti. ia ct oe ohe ah ook Skabace cn it vea lige gas enentanensa 30 Vegetative cells 5—8.5u in diameter; wall of ZYSOSPOTe SCrODICUIALS OT VELEUCOSE. ¥....2c2.0-.c ese che tee taht qracs sh aneseeepogesmcs tes a Zygospores cruciate-quadrate, sides concave, 18—29u in diameter, 30—38u long; vegetative cells 8—10u Thalys (GuPiba 0 (21U2) eee ROU NY CEC Dy 2 Ua DOGS Boia iene RAW ot Poymer ai Ras M. punctata Zygospores quadrate, sides straight, 28—40u in diameter; vegetative cells (8)—14—16u in diameter........................ M. quadrangulata Zygospores quadrate with tumid margins, wall MUUUMTILE]y eESCTOOLCU ALE nfo 5 cece oo eco i paeta ee age cepaety tne exon neck eeas sacs M. tumidula Zygospores quadrate, with concave margins, wall THINMLEl Va WERENCOSCY |. Focihtt5. oy raed 2 ae eater e. orho mean sdwaeoetne M. gracilima Mougeotia abnormis Kisselew 1927, p. 301 [M. notabilis Hassall 1842, p. 46] Pl. 70, Figs. 3, 4 Filaments forming sparse entanglements; vegetative cells long- cylindric, 10-21,» in diameter, 50-111-( 250), long; chloroplast filling the length of the cell. Zygospores formed almost entirely within the conjugation tube but extending into and filling one of the gametan- gia; triangular or quadrate-ovate, with margins concave and median spore wall smooth; 24-26, in diameter, 26-36, long. Our specimens are referred to M. abnormis on the basis of their agreement with the published partial description. Among other algae in ponds and lake margins. Wis. [ 299 ] Mougeotia americana Transeau 1918, p. 237 Filaments slender; vegetative cells 4-5. in diameter, 40-120, long, becoming geniculate in conjugation. Zygospores formed in the tube, but extending into both the gametangia; irregularly quadrate, the margins concave or convex, with angles produced and truncately rounded; median spore wall colorless and smooth; 13—24, in diameter, 18—32y long; sporangium membrane becom- ing filled with pectic substance. Douglas Lake, Michigan. Mougeotia calcarea (Cleve) Wittrock 1872, p. 40 Vegetative cells 8-14 in diameter, 40-280, long, filaments be- coming geniculate in conjugation. Zygospores formed in the tube but extending into the gametangia; globose or somewhat angular, the wall colorless and smooth; 25-30 in diameter, or (if angular) 22-28y in diameter, 30-50, long. Mich. Mougeotia calcarea var. bicalyptra (Wittr.) Transeau 1926, p. 316 Vegetative cells 10-12. in diameter, 30-110» long; zygospores with thick end walls adjacent to the gametangia, extending into and at times completely dividing the gametangia. Mich. Mougeotia capucina (Bory) C. A. Agardh 1824, p. 84 Pl. 70, Figs. 5, 6 Filaments long and slender, forming purplish, cottony masses; vegetative cells 14-21, in diameter, 70-150-(280) » long; chloroplast a narrow axial band with 4-6 pyrenoids (sometimes as many as 12 or 16) ina single series. Zygospores formed in the tube but extending into and dividing both gametangia; irregularly quadrangular with concave margins, the wall brownish-violet and smooth; 50-74, in diameter, 80-100y long; with lamellate pectic substances deposited in the angles of the spore. This species is often found fruiting during late summer along lake margins where water has receded. It forms purple films on moist substrates or purple cloud-like masses about the stems of Chamaedaphne. A collection of M. capucina from a Sphagnum bog in Cheboygan County, Michigan, showed mature zygospores with minute puncta- [ 300 ] tions when viewed under oil immersion magnification (H. K. Phinney manuscript ). Entangled about reeds and in shallow water of beach pools; common in acid habitats and Sphagnum bogs. Mich., Wis. Mougeotia cyanea Transeau 1926, p. 321 Vegetative cells 14-18-(20) in diameter; chloroplast one-third to one-half the cell in length. Zygospores formed in the tube, not dividing the gametangia; compressed-globose; at right angles to the tube; wall blue, finely punctate; 30-40, in diameter, 38-48, long. Douglas Lake, Michigan. Mougeotia elegantula Wittrock 1872, p. 40 Pl. 70, Figs. 7, 8 Filaments very slender, becoming geniculate in conjugation; cells long-cylindric, 4-4.5 in diameter, 50-135p long; chloroplast a thin plate, not quite equalling the cell in length, containing 4-8 pyre- noids. Zygospores formed in the tube and dividing both gametangia; quadrate with concave margins, the wall smooth, hyaline; 18-25. in diameter. Forming cottony masses in shallow water. Mich., Wis. Mougeotia floridana Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 224 Vegetative cells 14-20 in diameter, 60-200, long; chloroplast with 6-8 pyrenoids in 1 series. Zygospores formed in the tube and extending into one gametangium; globose or triangular; the median wall yellow and smooth; 30-40 in diameter, 36-48, in long dimension. Mich. Mougeotia genuflexa (Dillw.) C. A. Agardh 1824, p. 83 Pl. 70, Figs. 9, 10 Filaments slender, frequently conjugated by geniculations but not producing zygospores; cells 25-38, in diameter, 50-100—( 225) p long; chloroplast a broad band filling the length of the cell, with several pyrenoids. Zygospores formed either by lateral or (more rarely) scalariform conjugation, within the tube, not dividing the gametangia; quadrately-ovate or subglobose; median wall smooth and hyaline; 30-35-(40) » in diameter. Among beds of vegetation in lagoons and lakes; rather common in Sphagnum bogs, growing luxuriantly in shaded habitats. Mich., Wis. [ 301 ] Mougeotia genuflexa var. gracilis Reinsch 1867, p. 215 Smaller than the typical; vegetative cells 15-24, in diameter; zygospores 24-30, in diameter. Mich. Mougeotia gracilima ( Hass.) Wittrock 1872, p. 40 Vegetative cells 5-7» in diameter, 55-140n long. Zygospores dividing both gametangia; quadrate with concave margins to retuse angles, the wall finely verrucose; 20-25, in diameter, 20-28p long. Mich. Mougeotia Hirnii Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 218 Vegetative cells 25-28. in diameter, 60-140, long. Zygospores formed in the tube, not dividing the gametangia; ovate; the median spore wall smooth, yellow to brown; 40—48, in diameter, 43—50y long. Mich. Mougeotia laetevirens (A. Braun) Wittrock in Wittrock & Nordstedt 1877, Algae Exsic. No. 58 Pl. 70, Figs. 11-14 Filaments forming light green, cottony growth; cells long-cylindric; (22)-27—40p in diameter, up to 350, long; chloroplast a broad band extending the full length of the cell, containing an indefinite number of irregularly arranged pyrenoids. Zygospores formed by scalariform conjugation in the tube, not dividing the gametangia; cylindric or ovate in front view, with lateral walls convex, free walls concave; median wall smooth and brown; 36-50, in diameter, 45-73, long. Mich., Wis. Mougeotia laevis (Kuetz.) Archer 1866, p. 272 [Debarya laevis (Kuetz.) West & West] Pl. 70, Figs. 1, 2 Vegetative cells elongate-cylindric, 20-26, in diameter, up to 5 times the diameter in length; chloroplast with 2-4 pyrenoids. Zygospores formed in the conjugation tube, not dividing the game- tangia; ovate to broadly ellipsoid; outer wall smooth, median wall coarsely scrobiculate; 20-30-(36) » in diameter, 42-50» long. Shallow water of ponds and ditches. Mich., Wis. Mougeotia maltae Skuja 1926, p. 111 Vegetative cells 17-22 in diameter, up to 160, long; chloroplast with a single row of 4-8 pyrenoids. Zygospores formed in the tube, [ 302 ] not dividing the gametangia; globose; median spore wall blue and smooth; 30—35—( 40)» in diameter. Mich. Mougeotia micropora Taft in Transeau, Tiffany, Taft, & Li 1934, p. 218 Pl. 74, Fig. 5 Vegetative cells 18-234 in diameter, 60-160, long; chloroplast with 4-6 pyrenoids in 1 series. Zygospores formed in the tube, not dividing the gametangia; globose, ovate, or compressed, parallel with the tube; median spore wall brown and punctate; 26-36, in diameter, 26-30, long; sporangium finally becoming inclosed by a thick layer of pectose. Mich. Mougeotia nummuloides ( Hass.) DeToni 1889, p. 718 Vegetative cells 8-16. in diameter, 32-160, long. Zygospores formed in the tube, not dividing the gametangia; globose to ovate; median spore wall brown and scrobiculate; 17-37, in diameter. Mich. Mougeotia parvula Hassall 1843, p. 434 Vegetative cells 6-12 in diameter, 30-140 long; chloroplast 4 the length of the cell, with 4-6 pyrenoids. Zygospores formed in the tube, not dividing the gametangia; globose; median spore wall brown and smooth; 13-24, in diameter. Mich. Mougeotia pulchella Wittrock 1871, p. 88 Vegetative cells 24-29, in diameter, 48-150, long; chloroplast with pyrenoids in a single series. Zygospores formed in the tube, not dividing the gametangia; ovate or ellipsoid, with flattened ends; median spore wall brown and punctate; 28-35, in diameter, 40-50 long. Mich. Mougeotia punctata Wittrock 1867, p. 21 Pl. 71, Fig.1 Filaments forming sparse, cottony growths; cells short- or long- cylindric, 8-10 in diameter, (50)-115-135, long; chloroplast a broad plate with 4-6 (or more ?) pyrenoids. Zygospores formed in the tube and dividing both gametangia; quadrate with retuse margins; outer spore wall coarsely punctate or pitted; (18)-29y in diameter, 30-33-(38) » long. Among reeds.in a small lake of soft water. Wis. [ 303 ] Mougeotia quadrangulata Hassall 1843, p. 434 Pl. 71, Figs. 3-5 Vegetative cells long-cylindric, 14-16» in diameter, 135-150, long; chloroplast a broad plate extending the full length of the cell, with 4-6 pyrenoids. Zygospores formed in the tube, dividing both gametangia; quadrate, with straight or slightly retuse margins, ovate when seen from the side; wall finely scrobiculate or punctate, colorless; 28-40 in diameter. In shallow water of lake margins and swamps. Mich., Wis. Mougeotia recurva ( Hass.) DeToni 1889, p. 714 Vegetative cells 12-18» in diameter, 50-180, long. Zygospores formed in the tube, not dividing the gametangia; globose; median spore wall brown and smooth; 23—33p in diameter. Mich. Mougeotia Reinschii Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 224 Vegetative cells 9-13, in diameter, 80-160) long; chloroplast with 5-8 pyrenoids in a single series. Zygospores usually formed by lateral conjugation, or in the tube by scalariform conjugation, not dividing the gametangia; quadrangular-globose or rhomboid; me- dian spore wall yellow and smooth; 25-30, in diameter. Mich. Mougeotia robusta (DeBary ) Wittrock in Wittrock & Nordstedt 1884, Algae Exsic. No. 651 Pl. 74, Fig. 7 Vegetative cells 25-33. in diameter, 75-260p long; chloroplast with many irregularly placed pyrenoids. Zygospores formed in the tube, not dividing the gametangia; ovate to subglobose; median spore wall brown and scrobiculate; 35-41, in diameter, 47-54, long. Mich. Mougeotia robusta var. biornata Wittrock in Wittrock & Nordstedt 1884, Algae Exsic. No. 615 Vegetative cells 27-30, in diameter, 25-240» long. Zygospores with outer wall inwardly verrucose, median spore wall scrobiculate; 30-38, in diameter, 42-50, long. Mich. Mougeotia scalaris Hassall 1842, p. 45 Pipiierigss67 Vegetative cells 20-27—-(34) in diameter, 40-180,» long; chloro- plast a broad plate with 4 pyrenoids. Zygospores formed in the tube [ 304 ] by scalariform conjugation, not dividing the gametangia; globose or broadly ovate; walls smooth and golden brown; 25-3lp in diameter, 27—40p long. In littoral flora of many lakes. Mich., Wis. Mougeotia sphaerocarpa Wolle 1887, p. 227 Pl. 74, Fig. 6 Vegetative cells 19-24, in diameter, 60—-120—( 240) long; chloro- plast with 4-6 pyrenoids. Zygospores formed variably, sometimes dividing one or both gametangia; subglobose to ovate; median spore wall brown and smooth; 40-45, in diameter, or 36-40, in diameter and 40-55y long. Mich. Mougeotia tumidula Transeau 1914, p. 297 PIT? Fig.2 Vegetative cells long-cylindric, 6-8» in diameter, up to 120,» long; chloroplast a broad plate with 4-8 pyrenoids in one series. Zygospores formed in the tube, dividing both gametangia; quadran- gular; both inner and outer spore walls minutely scrobiculate; 22-26, in diameter, 26-30, long. Mich. Mougeotia varians ( Wittr.) Czurda 1932, p. 79 Ploya, Figs. 1112 Vegetative cells 25-27, in diameter; chloroplast a broad band entirely filling the length of the cell, with 4 pyrenoids. Zygospores formed in the tube, dividing one of the gametangia; cylindric or drum-shaped, the free walls concave, the walls adjoining the gametangia convex; median wall smooth and brown; 48-60, in diameter, 60-70—(78 ) » long. This species is smaller than M. laetevirens (A. Braun) Wittr. and also differs in that the zygospore completely fills the gametangial cell, whereas in M. laetevirens the spore is formed entirely within the conjugation tube. In the tychoplankton of soft water lakes. Mich., Wis. Mougeotia ventricosa ( Wittr.) Collins 1912, p. 69 Vegetative cells 5-8—(9)» in diameter, 100-140» long. Zygospores unknown. Aplanospores obliquely ellipsoid to subglobose; median spore wall yellow and smooth; 12-24, in diameter, 16-29, long. Mich. [ 305 ] Mougeotia virescens ( Hass.) Borge 1913, p. 43 PI. 72, Figs. 1, 2 Vegetative cells 8-9-(11) in diameter, 30-80-(130)p» long. Zygospores formed in the tube, dividing both gametangia; quadrate with concave margins and rounded angles; wall smooth and color- less; 29-34.5u in diameter. Our specimens agree with M. virescens except that the vegetative cells are a little longer than described. In a small pond, Sawyer County, Wisconsin. Mougeotia viridis (Kuetz.) Wittrock 1872, p. 39 Pl. 71, Figs. 8-10 Filaments slender, becoming geniculate in conjugation; cells 6-Sy in diameter, 24-40-(80), long; chloroplast a broad plate extending the full length of the cell with 4-6 pyrenoids. Zygospores formed in the tube, dividing both gametangia; quadrate, the sides concave, corners retuse; median spore wall smooth and colorless; 24—32y in diameter. This is the most common species of Mougeotia in our collections. It appears in many shallow water situations and in roadside trickles, seeps from banks, etc. Tychoplankter; in several lakes; in swamps. Mich., Wis. MOUGEOTIOPSIS Palla 1894, p. 228 Filaments slender, composed of short cylindrical cells; 1 axial, plate-like, folded chloroplast without pyrenoids; conjugation scala- riform, the zygospore formed in the tube, protruding into one or both of the gametangia and not cut off from them by a wall; entire contents of the gametangial cells used in the formation of the zygospore; gametangial cells not becoming filled with lamellate pectic substances. Mougeotiopsis should be compared with Debarya, from which it may be differentiated in the vegetative condition by the presence of pyrenoids in the latter. In the reproductive phase Mougeotiopsis may be identified by the lack of pectic substances in the old gametangial cells. In our specimens a gelatinous sheath was some- times present about the filaments. Mougeotiopsis calospora Palla 1894, p. 228 Pl. 69, Figs. 4-6 Filaments light green, long and loosely entangled. Cells short- cylindric, sometimes quadrate in the vegetative state, becoming elongate in conjugation; 12-14, in diameter, 14-18» long. Chloro- [ 306 } plast a broad, folded axial plate, almost as long as the cell (sometimes ulotrichaceous in appearance). Zygospores formed in the connecting tube by’scalariform conjugation, and extending into the gametangia; oblong or rectangular-oblong; outer spore wall smooth, middle wall with deep pits; 22-25, in diameter, 33-38, long (rarely longer). This species was once described as Mesogerron fluitans Brand and included in the Ulotrichaceae because of its Ulothrix-like chloroplast. Our specimens were found only in the vegetative condition, but this plant is so distinctive that it can be assigned to M. calospora. Rare in several lakes and Sphagnum bogs. The plants seems to be confined to soft water habitats. Mich., Wis. SPIROGYRA Link 1820, p.5 Filaments long and unbranched, usually without basal-distal differentiation but sometimes with rhizoidal branches developing laterally where the filament comes in contact with substrate. Cells cylindrical, short, to very long in some species, with plane (even and smooth), replicate, or colligate (exterior H-shaped piece) end walls. Chloroplast a parietal band or ribbon which may be spirally twisted 14 to 3 (rarely 8) turns, or may be nearly straight (as in genus Sirogonium, not separated here); 1-16 chloroplasts in a cell. Conjugation either lateral or scalariform, usually by the formation of tubes, rarely by geniculate bendings of the filament so that conjugating cells are brought into juxaposition. Zygospores formed in one of the gametangial cells, which may become swollen, depend- ing upon the species; zygospores ovate, subglobose, ellipsoid, or oblong, with 3-layered wall, of which the middle layer may be smooth or decorated and colored. Aplanospores uncommon, similar to the zygospores in shape and wall markings; rarely aplanospores alone occur. Spirogyra is the largest genus in number of species and the most common of Zygnemataceae. It is identifiable in the field by its bright green, cottony growths and its slippery mucilaginous texture. In hand, a mass of filaments is easily drawn out into a long fine thread. In deep cold springs and pools Spirogyra flourishes abundantly and vegetatively, forming enormous green ‘clouds’ several feet in diameter in favorable habitats. In shallow warm water it has a tendency to form floating mats, with conjugation and subsequent disintegration of the filaments occurring. During conjugation the plant masses become dull, dirty-green or brownish, often with a burnt-orange tinge, which is almost invariably macroscopic evidence that reproduction is in progress. Some species of Spirogyra seem to [ 307 ] prefer hard water habitats with a pH between 7.0 and 8.5 (S. crassa, for example). Others are always found in shallow water which is rich in organic acids and where there is a considerable amount of disintegrating vegetation. As in most other genera of the Zygnemataceae, species identifica- tion cannot be made without mature zygospores, or in some cases aplanospores. Of the 258 or more known species of Spirogyra, only 50 have been found fruiting in our region, hence the following key is greatly limited. In those species of Spirogyra which have a large number of closely spiraled chloroplasts a count may be made easily by focusing on a band at the upper side of the cell, counting this as 1. Then by focusing down, the number of bands which are seen to be crossed by this one and added to it will give the total number of chloroplasts. Key to the Species 1. End walls of cells plane (not folded) _—____..— = -—= =~ __ 13 1. End walls of cells replicate (infolded) — ------ —-- --- —- -— —- —--—— 2) 2. Median wall of zygospore smooth ____-_-------------------------------____-__-----—- 4 2. Median wall of zygospore not smooth —______---------------------------_______---- 3 3. Median spore wall with conical projections; spores 52-63. in diameter _____——_---------------- S. borysthenica 3. Median spore wall reticulate; spores 45-75 in diameter _______- S. inconstans 4. Conjugation tubes formed only from thy irra @allg 5 4. Conjugation tubes formed from both cells ——________---_-—------- 6 5. Zygospores ellipsoid; fertile cells inflated on both sides - __ S. Spreeiana 5. Zygospores ovate; fertile cells inflated on conjugating side — S. Grevilleana 6. Chloroplasts 1 (rarely 2) in each cell _-----_________-----------— 8 6. Chloroplasts 3-5 (2-4 in some cells) === ees petites. “feiss eee tT i 7. Vegetative cells 28-33, in diameter; zygospores 35—47u in diameter; fertile cells cylindric _____________-__-_-_--_____-____ S. gratiana 7. Vegetative cells 33-45, in diameter; zygospores 45-60 insdiameter> fertileycells inflated), = S. fallax 8. Vegetative cells 8-13-(15) in Glare te re ee neni S. tenuissima 8. Vegetative cells larger _-_------------------———-—--—— 9 9. Vegetative cells 15-20 in diameter (rarely with 2 chloroplasts ); fertile cells FROGSOVSTT SUAVE oe S. inflata 9. Vegetative cells larger -._____----------- 10 10, Spores ovate 2. ee 11 10, ‘Spores ellipsoid 2. ee 12 11. Inner layer of outer spore wall scrobiculate; vegetative cells (28)-32-36-(44)u in diameter; fertile cells cylindric —__. S. protecta 11. Both median and outer walls of spore smooth; vegetative cells 19-30. in diameter; fertile cells slightly enlarged — S. Weberi 12. Fertile cells much inflated, fusiform; vegetative Cells) 24-304 mnidiamecton ee ee S. Farlowii 12. Fertile cells cylindric; vegetative cells up to 40 in diameter _____ S. laxa 13. Chloroplast 1 (rarely 2) in each cell —-.----_________-_» 14 13. Chloroplasts 2-16 in each cell __---- -- --—- 88 . Conjugating tubes arising only or mostly from the male Celleshet cee 15 . Conjugating tubes arising from both cells; or conjugation ocurring by geniculate bending of the filaments Withaue bes. pei, toLmed.— . eke ee I itz 15. Vegetative cells 15—24y in diameter ___—____-____-_-_----_______-__ S. Collinsii lea Veretativercells larger sss == ne eee ee 16 16. Median spore wall punctate; spore 37-42u in diameter. S. micropunctata 16. Median spore wall smooth; spore 44—54y in diameter... S. reftexa ieeechandes poreswallysmooth == eS on je Miechan spore: wallydecoited = eS 18 18. Vegetative cells 11-14u in Giameten] == aaeaen one A Ores S. porangabae iseeVecctaverce|iswlarger == =) = SSS eS i 19m Median spore’ wall’scrobiculate = = S. scrobiculata (oe Mediansspore: wallizcticulate= Sa Ee 20 20. Spore ovate, 43-46 in diameter______________________ S. sulcata 20. Spore ellipsoid, 35-444 in diameter. Bats S. daedaleoides 21. Spores varied in shape, ovate, ellipsoid, or irregular when seen from the same angle; 24—36y in diameter ee pe re S. pratensis 21. Spores uniform in shape when seen fromthe same angle) 222 oN 22. Vegetative cells less than 15 in diameter S. flavescens 22. Vegetative cells more than 15y in TATA CET meee ee ce ne ee ere o3 23. Spores ovate ———._______________--- 24 23. Spores ellipsoid ———________ 28 24. Spores 18-20-(35) in diameter; vegetative cells AAGLDNS fitea e 6 N12 T6421 (=) GOs a el ee aan Rear as SeaPesae i S. subsalsa 24. Spores larger; vegetative cells mostly larger_—________________________-__- 25 25. Spores 38—50u in’ diameter —_________-_—_——— S. porticalis 25. Spores smaller, (28)—33—38—(39) mu in diameter ........0....00:1 cee 26 26. Vegetative cells 24-26, in diameter; spores 94-29u in diameter __ ae Mote. ay ee ee eee Sa TPTES 26. Vegetative cells and spores larger ___---------—------------------________---------- 27 Diesbertile icelisueylingsi@s 8 a eS S. longata O7/, Wwesdulle @alls travileawec! Gin lowtin GieleS. S. suecica 28. Sporangia cylindric (rarely slightly enlarged by thetsporeybut nok millated ies=) = 23 2 29 28. Sporangia inflated on one or both sides __-----------_-________-------- 82 29. Vegetative cells 48—62u in diameter_____--------__________- S. condensata 29. Vegetative cells smaller —___________-____---_---_____-___-________-__---—- 30 30. Vegetative cells 18-26 in diameter, relatively stout, up to 904 long; spores 28-33 in diameter_______-> S. communis 30. Vegetative cells greater in diameter, but relatively more slender; up to 240y long —______— 81 31. Vegetative cells 24—30u in diameter, up to 125 long; spores 28-33 in diameter______--------------—---—---------___- S. Juergensii 31. Vegetative cells averaging larger, 28-36-39, in diameter, up to 240» long; spores 27-37 in diameter —____________------------—_-_-- S. singularis 32. Vegetative cells 40-50y in diameter______----------------_- S. circumlineata 32. Vegetative cells smaller __________--___-- 33 33. Vegetative cells 16-24» in diameter. S. gracilis 33. Vegetative cells larger ———_______-___---_--___-_—__----____ 34 34. Sporangia (female cell) inflated on both sides — 37 34. Sporangia inflated only on one side ___------—---____---------------- 35 [ 309 ] . Sporangia inflated only on outer side; vegetative cells GO—3.5 coin cian te ys 55 eater ta Ree ee eee Evy S. Borgeana . Sporangia inflated mostly on the inner (conjugating) side 36 » Vegetative cells 23—30x, in diameter. 2) sa) es S. Teodoresci wy Vegetativercells)30—40.0. im) diameters em smen bane ne ese tv) S. varians . Spores 28-33. in diameter, short, up to 50u long; sporangia’ (decidedly mnfiated ssa. Fe er eee een a S. affinis . Spores averaging smaller, 24—30u in diameter, and much longer up to 90u; sporangia slightly inflated to 38m... S. catenaeformis . Conjugation by geniculate bending of filaments, without conjugation tubes (Sirogonium of some authors) 39 ;) Conjugation| by tubes formed: from:both’cells 2s 2 ee eee 40 . Vegetative cells 38—56u in diameter; spores 41-64 inidiameter; median spore: wall smooth =) /2 ih ees =e S. stictica . Vegetative cells 51-60. in diameter; spores 63-70u in diameter; median spore wall wrinkled or granular. S. pseudo floridana Median'sporemwalliismooth) i) 28221) a JA Ue SAN Enel oe SEEN Ste 2 41 Median spore; wall: not; smooths .2...28 4. a eae oe Te ee 49 . Vegetative cells 125-150» in diameter ...__________ S. ellipsospora wNviegetative cells smalleny: 20 este See ae eke ME seen ne ee ee 42 . Conjugating cells inflated (or cylindric in S. majuscula)...............00....... 43 muConjugatingiucellsteylinidnicy serene «ohio ae pee 44 . Vegetative cells 50-80u in diameter; chloroplasts 3-8... S. majuscula . Vegetative cells 40-50. in diameter; chloroplasts 2-3 —..________. S. dubia » Vegetative cells more) than (tou: inydiameter eee 45 Vegetative cells lessithan) 49. in diameters 2 eee 46 5. Spores 60-80-(85)u in diameter, 90-170 long, ends pointed S. nitida . Spores 87-108u in diameter, 120-155 long, ends not pointed __ S. jugalis . Spores ovate, cylindric-ovate (sometimes nearly globose) ——__-_____ 47 Hespotes) ellipsoid) sess eimai i, Se dae Jal ele elie le ena BEE le 48 . Chloroplasts 3; spores ovate to subglobose, 34—48 in diameter, 48-54 long ____.._.___---_---_-__ S. triplicata . Chloroplasts 2 (rarely 3 in some cells of the filament); spores cylindric-ovate to subglobose, 31-40 in diameter, 31-68» long _ S. decimina 48. Vegetative cells 40-44u in diameter, up to 240u long; chloroplasts 3, making 1-2 turns; spores 832—40u in diameter — S. Fuellebornei 48. Vegetative cells averaging smaller, 36-41 in diameter, up to 400u long; chloroplasts 2-3, making 2% to 3% turns ._____ S. rivularis 49. Vegetative cells more than 100u in diameter —_._____________-_- 50 49" Vegetative cells less: than’\ 100” in diameter) 2s 51 50. Vegetative cells 140-165, in diameter; spores compressed-ovate; median spore wall pitted__________________- S. crassa 50. Vegetative cells 118-140-(153)u in diameter; spores compressed-spheroid; median spore wall reticulate ______ S. maxima oll iSpores\ ellipsoid st? eae ee ee eee 52 9) SPOTES OV tee eee eee ee ee eS 53 52. Zygospores 32-42 in diameter, wall finely scrobiculate S. oriertalis 52. Zygospores averaging larger, 838-62u in diameter; median spore wall irregularly sreticulate 000000 S. rhizobrachialis 53. Vegetative cells 23-25-(29)u in diameter —____________. S. aequinoctialis oo. Vegetative ;cellsy larger _ 54 o4. Fertile cells cylindric =. esos) tt) eee eee S. novae-angliae 54- Fertile’ cellsisimflated! £03 282 ee S. fluviatilis [ 310 ] Spirogyra aequinoctialis G. S. West 1907, p. 105 Pl. 72, Figs. 3, 4 Vegetative cells long-cylindric, 23-29, in diameter, up to 150 long, with plane end walls. Chloroplasts 2-3, with crenate margins and large pyrenoids, making 1 to 1% turns. Conjugation by tubes from both gametangia, the receiving cells becoming symmetrically inflated. Zygospores ovate or elongate-ellipsoid, with broadly rounded poles; median spore wall with deep pits; (40)—41—50, in diameter, (52)—72—77y long. In shallow water of lake margins. Wis. Spirogyra affinis ( Hass.) Petit 1880, p. 18 Filaments of rather stout cylindrical cells, 27-30. in diameter, up to 90u long, with plane end walls. Chloroplast solitary, making 1 to 31/2 turns. Conjugation mostly lateral, but also scalariform, tubes from both cells; sporangia inflated on both sides. Zygo- spores ellipsoid; wall layers smooth; 28—334 in diameter, 30—50, long. Common in ponds and swamps. Mich., Wis. Spirogyra Borgeana Transeau 1915, p. 23 PI77,. Figs: 7,8 Filaments of cylindrical cells, usually slender, 30-35, in diameter, up to 200, long, with plane end walls. Chloroplast solitary, making 114 to 5 turns. Conjugation scalariform; sporangia inflated only on the outer side. Zygospores ellipsoid; wall layers smooth; 33-40, in diameter, 54-70» long. Mich. Spirogyra borysthenica Kasanowsky & Smirnoff 1913, p. 139 Filaments of slender cylindrical cells, 30-40, in diameter, 130-450, long, with replicate end walls; chloroplasts 3-4, making 14 to 21/2 turns. Conjugation scalariform, tubes from both cells, fertile cells swollen to twice the diameter of the vegetative cells. Zygo- spores ellipsoid to fusiform; median wall with papillae; 52-63, in diameter, 100—180, long. Mich. Spirogyra catenaeformis ( Hass.) Kuetzing 1849, p. 438 Filaments of rather stout cylindrical cells, 24-27-(32) in dia- meter and up to 5 diameters in length, with plane end walls; chloroplast solitary, making 1 to 6 turns. Conjugation by tubes from both gametangia; fertile cells swollen; the sporangia inflated on both sides. Zygospores ellipsoid; wall layers smooth; 24-30, in diameter, 55-90, long. Mich., Wis. 311] Spirogyra circumlineata Transeau 1914, p. 293 Pl. 74, Fig. 8 Filaments of rather stout cells, 40-50, in diameter and 3-6 times their diameter in length, with plane end walls; chloroplast solitary, making 4 to 8 turns. Conjugation by tubes from both gametangia; sporangia inflated mostly on the inner (conjugating) side. Zygo- spores ellipsoid; wall layers smooth; 40-50» in diameter, 70-125p long. Mich. Spirogyra Collinsii (Lewis) Printz 1927, p. 372 Pl. 77, Figs. 4-6 Filaments of rather slender cells, 15-24, in diameter, and about 5 times as long as broad, with plane end walls; chloroplast solitary. Conjugation scalariform and lateral, the tube formed by the male gametangium only; sporangia inflated slightly on both sides to contain the spore; the male gametangium formed by a partitioning off of one end of a vegetative cell. Zygospores ellipsoid; median wall coarsely punctate; 35, in diameter, 60» long. Mich., Wis. Spirogyra communis ( Hass.) Kuetzing 1849, p. 439 Vegetative cells slender, cylindric, (18)-20-26, in diameter, (35)- 65-100, long, with plane end walls; chloroplast solitary, making 114 to 4 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid, with narrowly rounded poles; median spore wall smooth, colorless, or yellowish in age; 19-23, in diameter, 36-69, long. Common in ponds and swamps. Mich., Wis. Spirogyra condensata (Vauch.) Kuetzing 1843, p. 279 Pl. 72, Figs. 5, 6 Filaments of rather stout vegetative cells, (48)-53-62, in diameter, 45-94—(120) long, with plane end walls; chloroplast solitary, mak- ing 14 to 4 turns. Conjugation by tubes from both gametangia, or lateral; fertile cells cylindric. Zygospores ellipsoid; median spore wall smooth and brown; 34-38 in diameter, 50-75y long. In alkaline bog lakes. Mich. Spirogyra crassa Kuetzing 1843, p. 280 Pli2,, Kigs..75.8 Filaments coarse, stout, feeling glassy to the touch; vegetative cells cells (133)-—140-160, in diameter, quadrate or 2 times the diameter in length, with plane end walls; chloroplasts 6-12 (usually 8-10), [ 312 ] slender, making 14 to 1 turn. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ovate or laterally flattened, the poles broadly rounded; median spore wall finely pitted and brown; (80)—120—140, in diameter, 166-175, long. Forming dark green masses of coarse filaments in quiet water of bogs and pooled streams; apparently specific for hard water habitats. Mich., Wis. Spirogyra daedaleoides Czurda 1932, p. 180 Pl. 72, Figs. 9-11 Filaments of rather stout cylindrical cells, 30-35 in diameter, 70-148-(240) long, with plane end walls; chloroplast solitary, making 3 to 4 turns. Conjugation scalariform by tubes from both gametangia, or lateral; fertile cells becoming inflated. Zygospores ellipsoid or ovate-ellipsoid; median spore wall coarsely reticulate and brown; 35-(44) in diameter, (46)-—59-77, long. In hard water lakes. Mich., Wis. Spirogyra decimina (Mueller) Kuetzing 1843, p. 280 Filaments of rather stout cylindric cells, 34-40» in diameter, 60-125-(150), long, with plane end walls; chloroplasts 2 (rarely 3) in each cell, broad, making 2 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores cylindric-ovate, rarely subglobose; median spore wall smooth; 31-40, in diameter, 31-68— (75) long. Forming cloudy masses on false bottom of an alkaline bog lake. Mich., Wis. Spirogyra dubia Kuetzing 1855, p. 8. Tab. Phyc. V Filaments of rather stout cylindrical cells, (40)—43-50p in diam- eter and up to 21% times the diameter in length, with plane end walls. Chloroplasts 2 (sometimes 3), making 1 to 3 turns. Conjugation scalariform by tubes from both gametangia; fertile cells inflated. Zygospores globose or ovate; median wall smooth; 40p in diameter, up to 80, long. Mich., Wis. Spirogyra ellipsospora Transeau 1914, p. 294 Pl. 72, Fig. 12 Filaments of stout cylindric cells, 125-150, in diameter, 125-230- (500), long, with plane end walls; chloroplasts 3-8 narrow bands, making 14 to 5 turns. Conjugation by tubes from both gametangia; [ 313 ] fertile cells cylindric. Zygospores ellipsoid or cylindric-ellipsoid, not compressed; spore walls smooth, becoming yellow-brown in age; 100-140 in diameter, 160-255, long. This species is readily differentiated from other large forms in our collections (S. crassa and S. maxima) by the large ellipsoid spores with smooth walls. In our region it has not been collected in pure growths as have many other species of the genus. Among other filamentous algae in shallow water. Mich., Wis. Spirogyra fallax (Hansg.) Wille 1900a, p. 16 PI, 77, Wig. 10 Filaments of rather slender cylindrical cells, 33-45, in diameter and up to 8 times the diameter in length, with replicate (rarely plane) end walls; chloroplasts 3-5, making 14 to 14% turns (sometimes nearly straight). Conjugation scalariform, the tubes short but formed from both gametangia; fertile cells inflated (shortened). Zygospores ellipsoid; wall layers smooth; 45-60, in diameter. Mich. Spirogyra Farlowii Transeau 1914, p. 291 Filaments of rather long cylindrical cells 24-30, in diameter and up to 180% long, with replicate end walls; chloroplast solitary, making 214 to 6 turns. Conjugation scalariform by tubes from both gametangia; fertile cells fusiform, inflated. Zygospores ellipsoid; median spore wall smooth; 32-45, in diameter, 48-93, long. Mich. Spirogyra flavescens ( Hass.) Kuetzing 1849, p. 438 Filaments of slender cells, 11-13, in diameter and up to 4 times the diameter in length, with plane end walls; chloroplast solitary, making 1 to 2 turns. Conjugation scalariform by tubes from both gametangia, the fertile cells inflated. Zygospores ovate to cylindric- ovate; median spore wall smooth; 20» in diameter, up to 30 long. Mich. Spirogyra fluviatilis Hilse in Rabenhorst 1864-1868, Algen No. 1476 Pl. 73, Figs. 4, 5 Filaments of rather stout cells, (30)-36—40-(45) in diameter and 5-6 times the diameter in length, with plane end walls; chloroplasts 3-5, making 11% to 214 turns. Conjugation scalariform by tubes from both gametangia, fertile cells becoming inflated. Zygospores ovate; median spore wall wrinkled and irregularly pitted; 42-44-(65) in diameter, 59-77—(110) » long. In pooled streams; common in lakes and ponds. Mich., Wis. [314] Spirogyra Fuellebornei Schmidle 1903, p. 76 Pl. 73, Fig. 6 Filaments of stout cylindrical cells, 40-44 in diameter, 120-200- (240) long, with plane end walls; chloroplasts 3-4, making 1 to 2 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid, with sharply rounded poles; median spore wall smooth and brown; 32-40, in diameter, 50-80, long. In an alkaline bog lake. Wis. Spirogyra gracilis (Hass.) Kuetzing 1849, p. 438 Filaments of rather stout cells, 16-24, in diameter and up to 5 times the diameter in length, with plane end walls; chloroplast solitary, making 1% to 3 turns. Conjugation scalariform by tubes from both gametangia; sporangium inflated on the conjugation side only. Zygospores ellipsoid; median spore wall smooth; 27-30» in diameter and up to 60, long. Mich. Spirogyra gratiana Transeau 1938, p. 528 Pl. 74, Fig. 9 Filaments of elongate-cylindric cells, 28-33, in diameter, 144400» long, with replicate end walls; chloroplasts (2)-3-(4). Conjugation lateral or scalariform by tubes from both gametangia; fertile cells cylindric or merely enlarged. Zygospores ellipsoid or cylindric- ellipsoid; median spore wall smooth and yellow; 35-47, in diameter, 108-223, long. Rock pool from north shore of Lake Superior. Spirogyra Grevilleana ( Hass.) Kuetzing 1849, p. 438 Pl. 74, Fig. 11 Filaments of rather slender cells, 21-25—-(28) in diameter and up to 10 times the diameter in length, with replicate end walls; chloroplast solitary (rarely 2 in each cell), making 4-5 (up to 9) turns. Conjugation scalariform, the tubes formed from the male gametangium only; fertile cells inflated on the conjugation side. Zygospores ovate; median spore wall smooth; 30-36, in diameter and up to 214 times the diameter in length. Mich. Spirogyra inconstans Collins 1912, p. 74 Filaments of rather slender cells, 30u in diameter and up to 15 times the diameter in length, with replicate end walls; chloroplasts 8-4 (rarely only 2), making 1 to 3 turns. Conjugation scalariform [ 315 ] by tubes from both gametangia; fertile cells inflated. Zygospores ellipsoid; median wall reticulate; 45-75» in diameter and up to 125y long. Mich. Spirogyra inflata (Vauch.) Kuetzing 1843, p. 279 Filaments of rather slender cells, 15-20» in diameter and up to § times the diameter in length, with replicate end walls; chloroplast solitary (rarely 2), making 3 to 8 turns. Conjugation scalariform by tubes from both gametangia; fertile cells inflated, fusiform. Zygo- spores ellipsoid; median spore wall smooth; 42-48» in diameter and up to 96, long. Mich., Wis. Spirogyra Juergensii Kuetzing 1845, p. 222 PlN713, Figs. 7,/8 Filaments of moderately stout, long or short cylindrical cells, 24-26-(30)y in diameter, 60-125, long, with plane end walls; chloro- plast solitary, making 2 to 4 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid; median spore wall smooth and brown; 28-30-(33) in diameter, 40-75, long. Floating mats in a marsh; in swamps and ditches. Mich., Wis. Spirogyra jugalis (Fl. Dan.) Kuetzing 1845, p. 223 Filaments of large, stout cells, 90-100 in diameter, 1-114 times the diameter in length, with plane end walls; chloroplasts 3-4, making 1 to 2 turns. Conjugation scalariform by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid or cylindric- ellipsoid; wall layers smooth; 87-108, in diameter and 114 times the diameter in length. Mich. Spirogyra laxa Kuetzing 1849, p. 438 Filaments of rather stout cells, 30-33-( 40) in diameter and up to 230» long, with replicate end walls; chloroplast solitary, making 3 to 5 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid; median spore wall smooth and yellow; 30-33, in diameter, 60-82» long. Mich. Spirogyra longata (Vauch.) Kuetzing 1848, p. 279 Filaments of moderately stout cells, 20-36 in diameter and up to 10 times the diameter in length, with plane end walls; chloroplast solitary, making 2 to 5 turns; conjugation by tubes from both game- [ 316 ] tangia; fertile cells cylindric. Zygospores ovate or elongate-ovate; median spore wall smooth but with a longitudinal suture, brownish; 30—(38) in diameter, 50—(83), long. Mich. Spirogyra majuscula Kuetzing 1849, p. 441 Pl. 74, Fig. 10 Filaments of stout cells, 50-80 in diameter, 80-500 long, with plane end walls; chloroplasts 3-8, nearly straight or making less than 14 turn. Conjugation by tubes from both gametangia; fertile cells cylindric (sometimes slightly swollen). Zygospores lenticular or spheroidal, laterally compressed; median spore wall smooth and brown; 57-72» in diameter, 45-60 wide. Mich. Spirogyra maxima ( Hass.) Wittrock 1882, p. 57 Filaments of rather stout, short-cylindric cells (118)-145-153, in diameter, with plane end walls; chloroplasts 6-8, making 14 to %4 turn. Conjugation scalariform by tubes from both gametangia; fertile cells cylindric. Zygospores compressed-globose or lentil-shaped; median spore wall finely reticulate; 100-120» in diameter, 70-95, wide. In an alkaline bog lake. Mich., Wis. Spirogyra micropunctata Transeau 1915, p. 27 Pl (3, Big: 9 Filaments of fairly stout cells, 30-33-(36) in diameter, 108—114— (300) long, with plane end walls; chloroplast solitary, making 2 to 4 turns. Conjugation scalariform by tubes from the male gametangium only; fertile cells becoming slightly inflated. Zygospores ellipsoid, the poles broadly rounded; median spore wall finely and densely punctate; 37-42, in diameter, 57-70-( 100)» long. In bogs and ditches. Mich. Spirogyra mirabilis ( Hass.) Kuetzing 1849, p. 438 PL 7 7ebige | Filaments of slender cells, 24—26-(27), in diameter and up to 10 times the diameter in length, with plane end walls; chloroplast soli- tary, making 4 to 7 turns. Conjugation by tubes from both game- tangia; fertile cells inflated. Zygospores ovate to ellipsoid; median spore wall smooth and brown; 24-29, in diameter, 50-83, long. Mich. [ 317 ] Spirogyra nitida ( Dillw.) Link 1833, p. 262 Pl. 73, Fig. 10 Filaments of rather stout cells, 60-80, in diameter, 90-166—(170) » long, with plane end walls; chloroplasts 3-5, making 44 to 11% turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid or cylindric-ellipsoid, with sharply rounded poles; median spore wall smooth and brown; 60-77-(85)p in diam- eter, 90-118—( 170)» long. Tychoplankter; in shallow water of lakes and marshes. Mich., Wis. Spirogyra novae-angliae Transeau 1915, p. 26 Pl. 75, Figs. 1-3 Filaments of rather stout cells, 49-60, in diameter, 140—-240-(390) long, with plane end walls; chloroplasts 3-5, broad, making 1% to 4 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ovate to ovate-ellipsoid; median spore wall irregularly reticulate and brown; 50-60, in diameter, 82-92-( 120) long. Forming sparse floating clots in several lakes. Mich., Wis. Spirogyra orientalis West & West 1907, p. 186 Vegetative cells 30-31, in diameter, 90-160, long, with plane end walls; chloroplasts 3, making 1 to 1% turns. Conjugation scalariform by tubes from both gametangia; fertile cells inflated. Zygospores ellipsoid; median spore wall finely scrobiculate; 32-42, in diameter, 61-67 long. Mich. Spirogyra porangabae Transeau 1938, p. 525 Pl. 77, Figs. 2,3 Vegetative cells 11-14.5, in diameter, 65-145p long, with plane end walls; chloroplast solitary, making 4 to 9 turns. Conjugation scalariform by tubes from both gametangia; fertile cells slightly inflated (or merely enlarged to contain the spore). Zygospores ellipsoid; median spore wall irregularly punctate when mature, yellow; 21-27, in diameter, 47-54, long. Mich. Spirogyra porticalis (Muell.) Cleve 1868, p. 22 Pl. 75, Fig. 10 Filaments of rather stout cells, 40-50y in diameter, 68-200» long, with plane end walls; chloroplast solitary, making 3 to 4 turns. Conjugation scalariform by tubes from both gametangia; fertile [ 318 ] cells sometimes inflated. Zygospores ovate to subglobose-ovate; median spore wall smooth and yellow; 38-50, in diameter, 50-83. long. Coe in shallow water of lakes, swamps, and roadside ditches. Mich., Wis. Spirogyra pratensis Transeau 1914, p. 292 Pl. 75, Figs. 4-6 Filaments of rather slender cells, 17-20, in diameter, 80-95-(240). long, with plane end walls; chloroplast solitary (rarely 2), making 1 to 8 turns. Conjugation by tubes from both gametangia; fertile colls inflated. Zygospores ellipsoid to subcylindric-ovate; median spore wall smooth, yellow at maturity; 24-36, in diameter, 50-60- (70) » long. In a small pooled stream. Mich. Spirogyra protecta Wood 1872, p. 165 Vegetative cells 32-36-(44)» in diameter, 120-475,» long, with replicate end walls; chloroplast solitary making 4 to 5 turns. Con- jugation by tubes from both gametangia; fertile cells cylindric or slightly enlarged, sterile cells becoming inflated during conjugation. Zygospores ovate or cylindric-ovate; median spore wall smooth and yellow, inner scrobiculate; 36—42—(50)y in diameter, 66— 130, long. Mich. Spirogyra pseudofloridana Prescott 1944, p. 360 Pl. 75, Figs. 7-9 Filaments of stout cells, 51-60, in diameter and 3-5 times the diameter in length, with plane end walls; chloroplasts 4 (rarely 5), narrow, making 14 to 1% loose turns. Conjugation by geniculate bending of filaments, without tubes being formed; gametangia becoming shortened and thickened and apparently cut off from vegetative cells; fertile cells becoming slightly inflated. Zygospores ellipsoid, with narrowly rounded poles; median spore wall rough- ened with irregular granulations and wrinkles (not regularly re- ticulate), brown; 63-70, in diameter, 100-120, long. This species should be compared with S. illinoisensis Transeau and S. floridana Transeau. It is smaller than the former and has fewer chloroplasts. From the latter it differs chiefly in the decoration of the mesospore. Floating in a lagoon. Wis. Spirogyra reflexa Transeau 1915, p. 28 Vegetative cells 30-40, in diameter, 120-300, long, with plane end walls; chloroplast solitary, making 3 to 8 turns. Conjugation by tubes [ 319 ] from the male gametangia only; fertile cells grouped, in series of 2-4. Zygospores ellipsoid; median spore wall smooth and yellow-brown; 44-54 in diameter, 90-150, long. Mich. Spirogyra rhizobrachialis Jao 1936a, p. 57 Pl. 76, Figs. 1, 2 Filaments of rather stout cells (40)—45-59, in diameter, 114-240, long, with plane end walls; chloroplasts 3-5, crenate and deeply toothed on the margins, making 11% to 21% turns. Conjugation by tubes from both gametangia; fertile cells cylindric, sterile cells fre- quently forming tubes which develop highly branched rhizoidal processes at their ends. Zygospores ellipsoid; median spore wall irregularly and coarsely reticulate, brown; (38 )—40-62, in diameter, 111 be long. Our specimens agree closely with this species in habit of growth and spore characters, but vary in dimensions from the original description. Bright green cottony masses in soft water lakes. Wis. Spirogyra rivularis ( Hass.) Rabenhorst 1868, p. 243 Vegetative cells 36-41, in diameter, 100-400, long, with plane end walls; chloroplasts 2-3, making 2% to 314 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellip- soid or cylindric-ellipsoid; median spore wall smooth. Mich. Spirogyra scrobiculata ( Stock.) Czurda 1932, p. 182 Pl. 76, Figs. 3, 4 Filaments of short cells, 30-34-(40), in diameter, (30)-90-136, long, with plane end walls; chloroplast solitary, making 1 to 5 turns. Conjugation by tubes from both gametangia, the fertile cells inflated on the conjugating side; zygospores ellipsoid, median spore wall deeply pitted and brown; 33-35-(38), in diameter, 44—50-(68) long. Among other algae in swamps. Mich., Wis. Spirogyra singularis Nordstedt 1880, p. 23 Vegetative cells 29-39, in diameter, with plane end walls; chloro- plast solitary. Conjugation by tubes from both gametangia; fertile cells cylindric. Zygospores ellipsoid or cylindric-ellipsoid, not later- ally compressed; median spore wall smooth; 27-37 in diameter. Mich. [ 320 ] Spirogyra Spreeiana Rabenhorst 1863, Algen No. 988 Pl. 77, Fig. 9 Vegetative cells 18-21-(25), in diameter and up to 25 times the diameter in length; end walls replicate; chloroplast solitary, mak- ing 11/2 to 4 turns, Conjugation tubes formed from the male gametangia only; fertile cells inflated on both sides. Zygospores ellipsoid, median spore wall smooth and yellowish; 30—36, in diameter, 55—100. long. Mich. Spirogyra stictica (Engl. Bot.) Wille 1884, p. 34 Pl. 76, Figs. 5-7 Filaments of short or long cells, 38-56 in diameter, 80-300p long, with plane end walls; chloroplasts 2-6, straight or making 14 turn, Conjugation by geniculate bending of the filaments; connecting tubes not formed; the fertile cells becoming slightly swollen. Zygo- spores ellipsoid; median spore wall smooth; 41-64, in diameter, 75-118» long. In shallow water of lake margins, and in swamps. Mich., Wis. Spirogyra subsalsa Kuetzing 1845, p. 222 Pl. 73, Figs. 1-3 Filaments of slender cells 26-28. in diameter, (35)-148y long, with plane end walls; chloroplast solitary, making 114 to 3 turns. Conjugation by tubes from both gametangia; fertile cells becoming slightly swollen. Zygospores ellipsoid; median spore wall smooth, inner irregularly reticulate (?), and brown; (18)—33—35n in diameter, (30)—55—59, long. This species should be compared with S. esthonica (Skuja) Czurda and S. daedalea Lag., from which two species it differs in fundamental details of the spore characters. In swamps and other shallow water habitats. Wis. Spirogyra suecica (Borge) Transeau 1934a, p. 420 Vegetative cells 26-29. in diameter, 80-175, long, with plane end walls; chloroplast solitary. Conjugation by tubes from both gametangia; fertile cells inflated on both sides. Zygospores ovate; median spore wall smooth; 32-39, in diameter, 38-60, long. Mich. Spirogyra sulcata Blum 1943, p. 783 Filaments of rather stout cells 837-46y in diameter, 50-160, long, with plane end walls; chloroplast solitary (rarely 2), making 2 to 5 turns. Conjugation by tubes from both gametangia, which are [ 321 ] shortened, the receiving cell becoming somewhat swollen. Zygo- spores ovate; median spore wall reticulate and brown; 43-46, in diameter, 52-62» long. Wis. Spirogyra tenuissima ( Hass.) Kuetzing 1849, p. 437 Vegetative cells (8)-9-12-(15)y in diameter, 4-12 times the diam- eter in length with replicate end walls; chloroplast solitary, making 3 to 514 turns. Conjugation by tubes from both gametangia; fertile cells fusiform, inflated. Zygospores ellipsoid; median spore wall smooth and yellowish; 30, in diameter. Mich. Spirogyra Teodoresci Transeau 1934a, p. 420 Vegetative cells 23-30, in diameter, 42-90p long, with plane end walls; chloroplast solitary, making 1 to 5 turns. Conjugation by tubes from both gametangia; fertile cells greatly inflated on the conjugat- ing side. Zygospores ellipsoid, varying to ovate or globose; median spore wall smooth; 26-33, in diameter, 45-55y. long. Mich. Spirogyra triplicata (Collins ) Transeau 1944, p. 243 Vegetative cells 34-40(48), in diameter, 2-4 times the diameter in length, with plane end walls; chloroplasts 3, making 1 to 2 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zy gospores ovate to subglobose, not compressed; median spore wall smooth; 34-48, in diameter, 48-54 long. Mich. Spirogyra varians ( Hass.) Kuetzing 1849, p. 439 Ble 76 yHigs: Let Filaments of short cells, (28)-33-(40)» in diameter, 51-85-(120) long, with plane end walls; chloroplast solitary, making 1% to 4 turns. Conjugation by tubes from both gametangia; fertile cells inflated on the conjugation side only. Zygospores ellipsoid or ovate-ellipsoid; median spore wall smooth; 32-40, in diameter, 50-63-( 100) long. Mich. Spirogyra Weberi Kuetzing 1843, p. 279 Pl. 76, Figs. 8-10 Filaments of long cells, 19-30» in diameter, 80-480, long, with replicate end walls; chloroplast solitary, broad, making 3 to 614 turns. Conjugation by tubes from both gametangia; fertile cells cylindric. Zy gospores cylindric-ovate; median spore wall smooth and brown; 21-25 in diameter, 30-95, long. This species has never been found in pure growth; it seems always [ 322 | to be mixed with other filamentous algae. The unusually long, slender cells and the long ovate spores are distinctive features. , Entangled among other algae in many lakes and swamps; common. Mich., Wis. ZYGNEMA C. A. Agardh 1824, p. 77 Unbranched filaments of short or long cylindrical cells with plane end walls, inclosed by a soft (usually) mucilaginous sheath, rarely with irregular rhizoidal outgrowths of a few cells when in contact with the substrate; chloroplasts 2 (rarely 4) axial, stellate masses, each containing a large central pyrenoid with a conspicuous starch sheath. Conjugation mostly scalariform, with the zygospores formed in the connecting tube, or rarely in one of the gametangia, but not cut off by membranes from the gametangial cells. Zygospores spheri- cal, ovate, or ellipsoid, with a thick, 3-layered wall, the outer and middle layers variously sculptured with scrobiculations and puncta- tions. Asexual reproduction by aplanospores and akinetes. The genus Zygnema contains about 85 known species, and many more of these certainly occur in our region than can be listed now. Numerous collections of Zygema were made in the sterile condition and are, therefore, unidentifiable. One species was invariably found in soft water lakes attached about the culms of Scirpus spp., where it formed pale green, cottony masses. Although this species was collected repeatedly at several different seasons no fruiting speci- mens were found. This is interpreted as having a distinct ecological significance, and several possible explanations present themselves. One of these has to do with water chemistry. Species of both Zygnemataceae and Oedogoniaceae were found to flourish vegeta- tively in soft water lakes but were scarcely ever collected in a fruiting condition. In hard water lakes or in shallow ponds where there was a high concentration of organic matter and organic acids, these plants are more luxuriant and fruit abundantly. Key to the Species 1. Zygospores not formed; conjugation unknown; reproduction by aplanospores; vegetative cells 44-54 in diameter. Z. sterile 1. Zygospores formed by conjugation; aplanospores present orbabsent; vegetative cells smaller 02 so 9) peeopore wall bilge when mature: ole! tiles bei 3 2. Spore wall yellow, yellow-brown, or colorless when mature... 6 3. Spores formed in one of the gametangia________________. Z. chalybeospermum 3. Spores formed in the conjugation tube, extending mao tue, Carmietan pia oro bsesen econ eas | ae ee 4 aeeNiedian, ‘Spore wall, ‘smootlal.7) 5.000)... ade isi cetsteane nee. Z. cyanosporum Paiccian, spore «wall: punctate! oy 08 ogy) xcen he. ab aid a teeta eee 5 5. Median spore wall coarsely punctate, 33—36y in GAM CLE Ie ces ss se nnaek ust saccem ioar cea! teehee aay eae ae Z. synadelphum 5. Median spore wall finely punctate; Spores 2026 sin diameter, tA ae ee ee ete eee ee Z. carinatum 6. Spores formed mostly within the conjugating tube 9 6) Spores) formed in ome Ob the (ametam gia weeme enone Sees ec 7 7. Vegetative cells 20-24 in diameter; gametangia inflated and shortened; spore wall smooth =. Z. leiospermum 7. Vegetative cells larger in diameter; gametangia cylindricalor inflatedyonlyon-one side | 9 8 8: Mediant-wall"ofizygospore: smooths = Z. insigne 8: iMediantspore; walljscrobiculate:22%.. 1. = ee ee Z. stellinum OL \Vegetativescells 24-40. sim (diameter). 2. ee 10 Ol Wevetative cells: 14-20 ini diameter. a. ke ee ee Il 10. Vegetative cells 30-40. in diameter; spores 35-50y in diameter, wali with pitsy2=S-imt diameter ses seu se eee ee Z. pectinatum 10. Vegetative cells 24-33 in diameter; spores 24—32u in diameter, wall with pits less than 2u in diameter —___._____________ _._ Z. conspicuum 11. Median spore wall minutely punctate —..____________ Z. micropunctatum Ie Mediantspore; -walliscrobiculate === se eee Z. decussatum Zygnema carinatum Taft in Transeau, Tiffany, Taft, and Li 1934, p. 210 Pl oa bige ial Vegetative cells 16-18, in diameter, 33-36, long; fertile cells not inflated. Zygospores formed in the tube; compressed-globose, ovate, or top-shaped, compressed at right angles to the tube; median spore wall blue and punctate, with a conspicuous transverse suture; 23-26 in diameter, 29-33 long. Sporangium finally encased in a thick pectic layer. Mich. Zygnema chalybeospermum Hansgirg 1892, p. 243 Pl. 74, Fig. 2 Vegetative cells 24-27, in diameter and up to 3 times the diameter in length; fertile cells cylindrical (shortened). Zygospores formed in one of the gametangia; globose or broadly ovate; median wall blue and smooth; 30-35, in diameter, 30-38, long. Mich. Zygnema conspicuum ( Hass.) Transeau 1934, p. 208 Vegetative cells (18)-22-27-(33) in diameter, 50-90—-( 100), long; fertile cells not inflated. Zygospores formed in the tube; globose or ovate; median wall brown and rather coarsely pitted, the pits 1.5-2 in diameter; the spores 24-32, in diameter, 26-33, long. Mich. [ 324 ] Zygnema cyanosporum Cleve 1869, p. 28 Vegetative cells (17)-20-(27), in diameter and up to 9 times the diameter in length; fertile cells not inflated. Zygospores formed in the tube; globose or depressed-globose, compressed at right angles to the tube; median layer blue and smooth; 34—40, in diameter. Mich. Zygnema decussatum (Vauch.) Transeau 1914, p. 290 Vegetative cells 18-20, in diameter and up to 100, long, the wall without a thick layer of mucilage; fertile cells not inflated. Zy go- spores formed in the tube; globose or depressed-globose; median spore wall brown and scrobiculate; 27-30 in diameter. Mich. Zygnema insigne ( Hass.) Kuetzing 1849, p. 444 Vegetative cells 26-30. in diameter, 1-2 times the diameter in length; fertile cells cylindrical or inflated on one side only. Zygo- spores formed in one of the gametangia; subglobose to ovate; median wall brown and smooth; 32, in diameter, or (ovate spores) 26y in diameter, 32, long. Mich. Zygnema leiospermum DeBary 1858, p. 77 PITS 4 Bigs Vegetative cells 20-24, in diameter, quadrate; fertile cells enlarged but not distinctly inflated. Zygospores formed in one of the game- tangia; globose; median wall brown and smooth; 23-30, in diameter. Mich. Zygnema micropunctatum Transeau 1934, p: 210 Pl. 78,’ Fig. 12 Vegetative cells 14-16 in diameter, 24-52 long; fertile cells not inflated. Zygospores formed in the tube; depressed-globose or ovate, compressed at right angles to the conjugation tube; median wall yellow-brown and minutely punctate; 28-32, in diameter, 3640, long. Mich. Zygnema pectinatum (Vauch.) C. A. Agardh 1817, p. 102 Pl. 69, Figs. 9, 10 Filaments forming light green, cottony masses; vegetative eells 30-37-(40) in diameter, up to 80» long, usually inclosed by a soft mucilaginous sheath; fertile cells not inflated. Zygospores formed [ 325 ] in the tube; globose; median spore wall brown and pitted; 35-50, in diameter. Rare in a few lakes; forming floating masses among larger vege- tation or entangled about the culms of rushes in shallow water, Mich., Wis. Zygnema stellinum (Vauch.) C. A. Agardh 1824, p. 77 Filaments forming green, mucilaginous masses, floating free or sometimes in pooled seeps on banks; vegetative cells (25 )-28-26- (40) in diameter, quadrate or up to 3 times the diameter in length (mostly about 70,); fertile cells not inflated. Zygospores formed in one of the gametangia; broadly ovate or oblong; median layer brown and deeply pitted; 30-35, in diameter, 35-48, long. In Sphagnum bogs and sloughs. Mich., Wis. Zygnema sterile Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 212 Filaments scattered among other algae and seldom forming pure masses; vegetative cells 44-54» in diameter, 22-69, long, with a thick wall and inclosed by a firm pectic sheath which may be as much as 15y in thickness, the sheath often deeply constricted at the plane of the cross walls; cell contents very dense and so nearly opaque that the individual chloroplasts can scarcely be discerned. Conjugation not known; reproduction by thick-walled, scrobiculate akinetes which fill the cell when mature. Common; intermingled with other algae in shallow water, espe- cially in small lakes and ponds where there is a high concentration of decomposing organic matter. Mich., Wis. Zygnema synadelphum Skuja 1926, p. 110 Pl. 74, Fig. 1 Vegetative cells 17-21 in diameter; fertile cells not inflated Zygospores formed in the tube; globose, or compressed parallel with the conjugation tube; median layer blue and scrobiculate; 33-36. in diameter. Mich. ZYGNEMOPSIS (Skuja) Transeau 1934, p. 203 Filaments slender, composed usually of cylindrical cells which are as much as 10 times their diameter in length; chloroplasts 2 steHate or cushion-like ‘masses, containing a single pyrenoid each. Conjugation scalariform (between dissociated cells in some species ?), the gametangia persisting and becoming filled with cellulose- [ 326 ] pectic compounds, usually deposited in layers. Zygospores formed in the enlarged conjugating tube, compressed-spheroid or quadrate in front view, the median spore wall smooth or variously sculptured and decorated, brownish in color. This genus should be compared with Zygnema, especially those species which have stellate chloroplasts. It is separated from that genus chiefly by the presence of swollen and filled gametangia. Key to the Species ieevieretative cells 16—o2. 1m, diameter. ts ee 2) SCO e Lani c eorsistialler ios ae 1 BONA SERS SIP AWN ee 3 2. Zygospores ovate or quadrangular-ovate, median-spore wall ‘scrobiculate J es Z. decussata 2. Zygospores quadrate, outer wall densely punctate_.____ Z. spiralis om Median and outer spore walls smooth =.) 4 Se Medianvor outer Spore| walls decorated 5 4. Vegetative cells 8-10—(12), in diameter, with PRTOUNGEALCIMOEODOIAS{S oc. 22880 2 eb we le Z. minuta 4. Vegetative cells 10—12u in diameter, with ig piate-vkevculovoplash = oe ne a ee eae Z. Tiffaniana 5. Median spore wall finely reticulate; spores 20-40u in diameter, 30—40y long; 1 chloroplast with 2 pyrenoids Z. americana 5. Median spore wall finely punctate; spores 14—24y in diameter, 20-27 long; 2 cushion-like chloroplasts in each cell Z. desmidioides Zygnemopsis americana ( Trans.) Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 215 Vegetative cells 9-12» in diameter, 27-120, long; chloroplast with 2 pyrenoids. Zygospores formed in the tube but extending into the gametangia; ovate or quadrangular-ovate in face view, the angles retuse or rounded; median wall verrucose; 20-40. in diameter, 30-40 long. Mich. Zygnemopsis decussata (‘Trans.) Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 214 PI. 74, Fig. 3 Vegetative cells 16-20 in diameter, 24-50, long; chloroplast with 2 pyrenoids. Zygospores irregular in shape, or ovate to quadrate- ovate, somewhat compressed parallel with the conjugation tube; the angles various, either rounded, retuse, or extended; median spore wall scrobiculate; 24-30 in diameter, 30-48, long. Mich. [ 827 ] Zygnemopsis desmidioides (West & West) Transeau in Transeau, Tiffany, Taft, & Li 1934, p. 215 Pl. 69, Fig. 8 Filaments short, slender, and fragile, much constricted at the cross walls, composed of cylindrical cells, broadly rounded at the apices, 8-llp in diameter, 25-40, long. Zygospores rectangular in front view, broadly ellipsoid in side view; the median wall finely and densely punctate; 14-24, in diameter, 20-27-(30)» in long dimension. Gametangia persisting about the spore as 4 horn-like processes filled with pectic compounds. Rare; in shallow water of swamps; lake margins. Mich., Wis. Zygnemopsis minuta Randhawa 1937, p. 312 Vegetative cells 8-10. in diameter, 36-46» long; chloroplasts 2 irregular cushion-like bodies. Reproduction mostly by lenticular aplanospores. Zygospores quadrate in a 4-lobed sporangium (some- times 3-lobed), formed by remains of gametangia; median spore wall brown and smooth; 22—24, in diameter. Conjugation usually between dissociated cells. Mich. Zygnemopsis spiralis (Fritsch ) Transeau in Transeau, Tiffany ,Taft, & Li 1934, p. 214 PIS69) Migs Filaments long, composed of short cylindrical cells, 17-22» in diameter and up to 130, long; chloroplasts 2 stellate bodies. Zygo- spores quadrate in outline, formed in the enlarged connecting tube but extending into the gametangial cells which form horn-like enlargements; outer spore wall brown and densely punctate; 30-36, in diameter, 48-54, in long dimension. Mich., Wis. Zygnemopsis Tiffaniana Transeau 1944, p. 244 Pl. 74, Fig. 4 Vegetative cells 10-12 in diameter, 30-60, long; chloroplasts with 2 pyrenoids. Zygospore quadrate, the margins either retuse or straight to angles which may be produced or retuse (concave ); median spore wall smooth; 20-24, in diameter, 28-324 long. Con- jugation frequently between dissociated cells. Mich. [ 328 ] ZYGOGONIUM Kuetzing 1843, p. 280 Filaments of short-cylindric or slightly tumid cells with lateral branches, either rhizoidal or several cells in length. Chloroplasts cushion- or pad-like, 2 in a cell, or appearing as 1 duplex body with an interconnecting narrow band; a pyrenoid in each chloroplast; at times the chloroplast showing short radiate processes similar to Zygnema; nucleus in the bridge between the 2 chloroplasts; cyto- plasm usually colorless but sometimes purplish, becoming brown. Conjugation lateral or scalariform by protuberances from both gametangia; only part of the cell contents serving as a gamete. Zygospore ovate, in a sporangium which is formed between the two gametangia and which splits along a median line; spore wall smooth or decorated; gametangia not becoming filled with pectic substances but with granular residues, Reproduction also by akinetes and aplanospores (more common than zygospores ). Zygogonium ericetorum Kuetzing 1845, p. 224 Pl. 78, Figs. 8-10 Filaments with cells 15-24, in diameter and 14--114,-(4) times the diameter in length, cylindrical or slightly constricted at the cross walls; cell walls thick; chloroplasts, cytoplasm, and conjugation as described for the genus; zygospore ovate or globose, 20-25, in diameter, the median spore wall smooth. In shallow water of Black Lake, Michigan; on damp soil and tree trunks arising from water along lake margin. CLASS CHAROPHYCEAE This unique group of plants occupies an isolated position from a taxonomic point of view. They have no known ancestors nor have they given rise to other living plant forms according to present information. They are alga-like in their reproductive habits and because of their pigmentation there is ample justification for giving them a place in the Chlorophyta. In many characteristics they are quite unlike the green algae, however, and are so unique that in some systems of classification the Charophyceae are considered to be a separate division in the plant kingdom. The Charophyceae are all macroscopic, having rhizoidal, erect stem-like branches and whorls of secondary branches, or ‘leaves’. They vary in height from 2 to 60 cm., growing erect or sprawling in the bottom of lakes or slow-flowing streams. In many forms vegetative proliferation occurs by stolons and special buds or [ 329 ] ‘bulbils’ which develop on subterranean rhizoidal branches. Hence it is customary to find members of this group in compact beds or ‘meadows. The stem has definite nodes and internodes. From the former, short branches of definite growth (the ‘leaves’) and longer branches of unlimited growth develop. The leaves and secondary branches may arise in whorls or in a dichotomous or trichotomous plan. The chracteristic manner of growth in the Charophyceae is unique among the Chlorophyta. A meristematic apical cell cuts off node and internodal segments and from the former all lateral branches and sex organs are produced. In one genus cortical cells also develop from the node region and extend both anteriorly and posteriorly along the internodal cell. Reproduction is heterogamous and the sex organs are relatively complex. There are both monoecious and dioecious species. The oogonia are large, ovoid, or subglobose cells containing a single egg and are inclosed by a definite number of spirally twisted corticating cells which form a crown, the cornula, at the apex. The oogonia, like the antheridia, are produced at a node of the stem or its leaves. The antheridia are globose and usually smaller than the oogonia but are frequently conspicuous because of their red color when mature (as is also the oogonium in some species). The shell of the antheridium is composed of a definite number of flat, shield-like cells which have radiating lobes, these interlocking with lobes from other cells. The shield cells bear internally a large number of multi- cellular filaments, in each cell of which a swimming antherozoid is produced. The oogonia may be above, below, or side by side with the antheridia, depending upon the genus. The reader is referred to Groves and Bullock-Webster (1920), Fritsch (1935), and Smith (1938) for detailed discussions of the morphology of the group and of the many characteristics which are of taxonomic importance. It is a class which requires special terminology and much careful study in dealing with its taxonomy. There is 1 order and 1 family, divided into 2 clearly recognizable tribes. ORDER CHARALES FAMILY CHARACEAE In the taxonomy of this family the arrangement of the sex organs, the presence or absence of cortical cells, and the number and arrangement of these, are the major fundamental characteristics upon which differentiations are made. [ 330 ] Key to the Tribes Crown of oogonium composed of 5 cells; oogonium always above the antheridium (in monoecious species) CHAREAE Crown of oogonium composed of 10 cells (5 pairs, 2 cut off from the tip of the cortical cells of the oogonium); oogonium below or beside the antheridium; stem uncorticated_..-_-_ NITELLEAE TRIBE NITELLEAE In this tribe the stem bears whorls of short branches and 2 or more branches of indefinite growth. The plan of branching is dicho- tomous or trichotomous, and in many forms the secondary branches or ‘leaves’ all terminate at about the same level and are usually less than the internodes in length so that (especially in some species of Nitella) a beaded appearance results. The plants are entirely un- corticated and in most forms (particularly Nitella) they are limp and flexible. The coronula (‘crown’) of the oogonium is composed of 10 cells in 2 tiers at the ends of the 5 corticating cells of the female organ. The antheridium may be vertical at the end of a short stalk from the node of a fertile branchlet, or lateral (Tolypella) and either sessile or stalked. In the monoecious species the oogonia are below the antheridia (Nitella) or above and beside them (Tolypella). Key to the Genera Branching regular and symmetrical; antheridia terminal and vertical on a branchlet in the furcations; oogoniaxbclomthe antheridiay 0 fs et Nitella Branching irregular or not symmetrical, some branches longer and giving a scraggly appearance; antheridia lateral in the furcations; oogonia beside the antheridia or appeaninpatosbesabove then: 2.02 ee Tolypella NITELLA (C. A. Agardh) Leonhardi 1863, p. 69 Branches of unlimited growth, usually 2 at each node, the sex- organ-bearing branches repeatedly forked and terminating at the same level; antheridia terminal on a short stalk among the furcations of the branchlets; oogonia lateral, either just below an antheridium, or solitary on the node of a ‘leaf.’ Key to the Species 1. Plants small, 2-5—(8) cm. tall; ultimate divisions omthe branchlets: (gays) po -ecliemies 2. oat a 2 1. Plants larger; ultimate divisions of the branchlets 1-celled_....- = 8 [ 331 ] to Whorls of verticils at the nodes globular in outline, gradually decreasing in size toward the apex of the main axis, forming minute tufts’ at the tip 222 N. tenuissima . Whorls of verticils at the nodes spreading, not forming compact globules, becoming compactly arranged at the anterior end and bo forming dense clusters cone-shaped in outline —_______ N. Batrachosperma 3. Plants monoecious Usp tat Rie IE MH cide ee ee N. flexilis Se Plants. Gideciqus 222-2 ee ee ee N. opaca Nitella Batrachosperma (Reichenb.) A. Braun 1847, p. 10 Pl. 78, Figs. 1-4 Plants minute and very delicate, up to 2 cm. (rarely 3 cm.) tall, with several branches arising from a basal node; internodal cells in the lower part of the thallus 2-3 times the length of the verticils, which are in whorls of 8 at the node, and spreading, the branchlets crowded toward the apex, forming a cone-shaped cluster at the tip; branchlets once or twice divided, the ultimate rays 2-celled, the terminal cell awl-shaped; monoecious; antheridia terminal on a short stalk in the furcation of a ‘leaf, 0.135-0.210 mm. in diameter; oogonia borne laterally to the antheridia and below them, with a persistent coronula; oospore globose, 0.27-0.30 mm. in diameter, dark brown in color, the outer membrane with reticulations. This species is the smallest and the most delicate one in our collections. Like N. tenuissima, it has a gray-green color, is often found embedded in silt in the bottoms of shallow ponds and lagoons and hence is easily overlooked. Mich. Nitella flexilis (L.) C. A. Agardh 1824, p. 124 Pl. 79; Figs: 1-3 Plants large (up to 30 cm. tall) and stout, with long internodes (about 2 times longer than the branchlets), repeatedly branched, especially long and sprawling stems in deep water; nodes bearing whorls of 6-8 branchlets, with the sex-organ-bearing branchlets usually shorter, forming dense clusters, the branchlets but little divided, usually only one, the ultimate rays 1-celled and ordinarily acuminate; sex organs monoecious, the oogonia 2-3, subglobose or broadly ovoid, 0.55-0.75 mm. in diameter, 0.625-0.9 mm. long, the investing cells showing 8—9 turns; antheridium 0.5-0.75 mm. in diameter. In shallow water of soft water lakes and Sphagnum bogs; from 10-12 meters. Mich., Wis. [ 332 ] Nitella opaca C. A. Agardh 1824, p. 124 Pl. 79, Figs. 4-10 Plants large and robust with very long internodes (2-4 times longer than the branchlets); nodes bearing 6-7 branchlets which may be either simple or once-divided, ultimate rays 1-celled and mucronate; fertile branchlets crowded, forming heads; sex organs dioecious, the oogonia 1-2, broadly ovoid, 0.5-0.565 mm. in diameter, 0.65-0.7 mm. long, the investing cells showing 7-9 turns, the crown 0.25-0.4 mm. high, deciduous; antheridia 0.65-0.75 mm. in diameter. Common; a very luxuriantly growing, bushy plant, often forming dense beds, especially in soft water lakes; sometimes found at a depth of 5-8 meters. Mich., Wis. Nitella tenuissima (Desv.) Kuetzing 1848, p. 319 Pl. 80, Figs. 1-7 Plants small, tufted, 2-8 cm. high, with several branches arising from a single basal node; stem very slender, bearing whorls of 6 branchlets which are short, densely crowded and form glomerules, giving a distinct beaded appearance to the plant; the branchlets forking 3-4 times, ending in 2-celled rays; sex organs monoecious, the oogonia spherical or broadly elliptic, about 260, (0.26 mm.) in diameter, 400. (0.4 mm.) long, invested by corticating cells that show 9 turns; antheridia about 0.175 mm. in diameter. Like N. Batrachosperma, this species is often overlooked because it grows in silt, with only the tips of the branches emergent. Growing in shallow water on silty bottoms, mostly in soft water or slightly acid lakes. Mich., Wis. TOLYPELLA (A. Braun) Leonhardi 1863, p. 72 Thallus relatively coarse, (8)-10-25 cm. high, light green or gray- green in color, usually irregularly branched, presenting a scraggly appearance; sterile branches 6-16 in a verticil, of variable length; fertile branches involving several long, and one head of short, branchlets; internodes of principal filament and of primary laterals long; uncorticated; primary laterals sparsely branched; branches terminating in a series of unbranched ray cells which may be pointed or bluntly rounded at the tip; monoecious (in our specimens), the antheridia sessile or at the ends of short lateral branchlets in the furcations; oogonia usually crowded, appearing to be above and also beside the antheridia on the same node, formed either at the base of a fertile branchlet or on one of the lower nodes, the coronula persistent or not; oospore round in cross section, light to orange- brown in color. [ 333 ] Tolypella intricata Leonhardi 1863, p. 32 Pl. 78, Figs. 5-7 Thallus 8-25 cm. tall, gray-green; sparsely branched with a few primary branches and dense heads of fertile branchlets subtended by laterals of unequal length; the primary ray including but few nodes from which 2 or 8 lateral branches arise, simple or again divided, the laterals but 8 or 4 cells in length, the terminal cell sharp-pointed or sometimes bluntly rounded; fertile branchlets densely clustered and including also long, coarse branchlets of irregular length; the primary branch with 2 or 3 nodes, each bearing 3-(4) lateral branches, the ultimate rays of the fertile branches 3- or 4-celled, the lateral branch rays branched at the first node and again branching, sometimes also branching from the second node, these branches simple if there are but 2 nodes in the branchlet; antheridia sessile, up to 0.3 mm. in diameter, lateral at the nodes of the fertile branchlets; oogonia at the base of or on the nodes of the fertile branchlets, several together, appearing above or beside the antheridia; oospore 0.3-0.318-(0.4)mm. in diameter, light brown when mature, decorated with 10-11 ridges, the outer membrane yellowish, thin, and granular. In hard and semi-hard water lakes, in shallow water where there is protection from wave action and strong currents. Mich. TRIBE CHAREAE In this tribe the stems usually have but a single branch of unlimited growth arising from the nodes of the stem. The whorls of branchlets are simple, having only short bracts or leaflets at their nodes rather than bifurcations. In one genus, Chara, most species are characterized by having the internodal cells of the stem corticated. The sex organs may be monoecious or dioecious, in our specimens (Chara) with the oogonium borne above the antheridium in the monoecious species. The coronula of the oogonium in this group is composed of but 5 cells, cut off from the tips of the spiral corticating cells of the oogonium. CHARA Linnaeus 1754, p. 491 These plants are usually stout and coarse of texture, when com- pared with Nitella. They are frequently encrusted with lime and thrive best in hard or semi-hard water lakes and slowly flowing streams. It is this character which has earned for them the common name of Stoneworts. The stem in most species is corticated by elements which develop from the node cells in both directions along [ 334 | the internodal cell and so meet cortical cells from the node above and below. The cortical cells in their development themselves cut off small node cells. These show as small round units in the series; often they are spiniferous. From the node cells of the corticating cells secondary corticals may be cut off and grow down alongside the primary elements. These may be more prominent than the primary, or less so, a specific character of taxonomic value. Some- times there are two such cells cut off, one on either side of the primary cortical cell. The results of the behavior of the node cells of the cortical elements are then: 1. The node cells may not produce laterals and the cortical cells are rather large and equal in number to the leaves, which are borne at the node of the stem. This condition is known as haplostichous cortication. 2. If the node cell of the cortical series cuts off one lateral so that the cortex is com- posed of alternating primary and secondary cells the condition is known as diplostichous, and there are twice as many cortical cells as there are leaves at the stem node. 3. The node cells of the cortical series may give rise to two laterals, one on either side, so that in the circumference of the stem the primary cells alternate with two secondary cortical cells, and there are three times as many cortical cells as there are leaves in the whorl at the stem node. This condi- tion is known as triplostichous. There are irregularities in these plans of arrangement, so that it is often necessary to examine many stem sections to obtain the necessary information for taxonomic consid- erations. Rarely the stems are ecorticate. In most forms, besides bearing a whorl of leaves, the stem node is encircled by a single or double row of spine-like cells, the stipulodes. The nodes of the leaves may be smooth or they may bear leaflets or bracts (bracteoles ). Some of these may be mere papillae, whereas others at the same node may be much elongated, especially at fertile nodes where there are usually 2 or 4 long bracts about the oogonium. The last 1 to 4 cells of the leaves may be ecorticate and the general form and arrangement of these cells at the tip, and the lateral elements given off just below the uncorticated cells at the end of the leaves are characteristics which are of taxonomic value also. There are both monoecious and dioecious species. In the former condition the oogonia are always borne above the antheridia, devel- oping, however, from the same initial cell in the node of the branchlet. Only the more conspicuous species of Chara were collected, and in the present treatment I have included one which has been previously reported. Hence only a few of the many forms which [ 335 ] undoubtedly occur in the region are included. In order to make an adequate study of this interesting group, dredging and other special methods of collecting would be required. Many species of Chara listed by Robinson (1906) occur in the range of this area, but none are specifically referred to Michigan and Wisconsin. See Allen (1888-1896), Robinson (l.c.), and Groves and Bullock- Webster (1924) for the taxonomy of Chara. Key to the Species i, Siem wincomnerniedl (Sonar) 2 es Stemsscorticated (Corticatay) ie. ot 2 AA A eae eT os 3 2. Bracts about the oogonium distinctly shorter (Haehair{davempanPstaurgenn am ibncaese meme Ae aces 1 AN ON eS ee a C. Braunii 2. Bracts about the oogonium as long as or longersthan)thesmaturesinuit 262 Sie Ay Was ae ee C. Schweinitzii 3. Cortication haplostichous (see definition above )—______ C. canescens 34 Corticationsdiplastichoussor) triplostichous= 224. -- tt) ie ts Be 4 Ave Cortications G@iplostichOUS= 2 2. Flagella of equal length; lorica absent -___-----_-__ ISOCHRYSIDINEAE 2. Flagella of unequal length; protoplast inclosed) by ia lorica 9 9. Cells twisted throughout their length >>> P. helikoides 9. Gells twisted only in the caudal portion —__________________. P. tortus 10. Cell with a short, straight, almost papilla-like caudus P. acuminatus 10. Cell with a conspicuous caudus, straight, eurved, or strongly retle xec semerstaee cee 11 11% ‘Gell -with\ evenly undulate margins 98. P. crenulata 11. Cell with margin entire, irregularly undulate, orenotched: unsymmetrical yiewel. ee See | Sat 12 12. Cell unsymmetrically fusiform, somewhat euglenoid P. asymmetrica 12. Cell ovoid or orbicular in outline, symmetrical or nearly so 13 [ 395 ] 13. Cell with a prominent dorsal flange, decidedly triangular when seen in end view (cf. P. Swirenkoi, which is somewhat triangular) ____. 16 13. Cell without a dorsal flange, not triangular in end view___-_---_. 14 14 Marem’ of ‘cell’ with prominent notches 22 ee ee 15 14s. Margin-of, cell Gntinre 252.225 1) ly 8 ee 17 15. Cell with 1 or 2 lateral notches; 1 large circular paramylon body —_-.... _.-.----- ss Mia VINE t P. pseudoswirenkoi 15. Cell with several notches in both sides; 1 large auduseveral ‘stall paramylon) bodies== == ee P. Birgei 16. Cell with a strongly decurved caudus.___.____---.------------------- P. orbicularis 16. Cell with the caudus straight or only slightly curved away from the longitudinal axis -______________ P. triqueter Lier Gells p15=2 5 up inudiameter sss teow i ed ee ee el ee ee 18 24, 24. «Cells. 80=50=(60)) i inadiaimetent 82S tel 8 ee ail . Paramylon plates 2 large oval rings, at least A thecell body im length. a2 See Sa ee ee ee ee P. alatus /Paramylon:plates:smalier, 2.or'several === ee ee 19 . Cells distinctly twisted in the posterior part, just above the caudus, where there is often a swelling; one side of the’ cell much’ thicker than/the other == 23. P. Lemmermannii . Cells not distinctly twisted in the posterior portion; without a/swelling; above the caudus === 20 . Cell ovoid to ellipsoid, with a straight or only slightly curved! caudus #2 = P. caudatus . Cell broadly ovoid to orbicular, with a short Caudus.curvingrto: the letee 2. es ee P. curvicauda . Cell distinctly twisted in the posterior part just above the caudus; paramylon bodies usually 2 large and several ‘small: plates == ee P. Lemmermannii . Cells not distinctly twisted above the caudus; patamylon bodies usually 2 large sings ise ee 22 . Cell orbicular, broadest below the transverse median line; caudus deflexed mostly to the right; cell-angiilar in end View sas. Mie S00 ht eee 23 . Cell ovoid or nearly so, broadest at the transverse median lines or above: ity 2. ee ee ee 24 . Cell twisting slightly into the caudus, which is prominent and elongate, slightly deflexed P. pleuronectes . Cell not twisting into the caudus, which isnshort. and) sharply. detlexed . es ee ee P. Swirenkoi Cell broadly ovoid or orbicular, with a strongly curved caudus; cells 50-100u long —._-...---..-------------------------- P. orbicularis Cells narrowly ovoid, somewhat unsymmetrical, with a nearly straight caudus; cells up to 48 long P. anacoelus Phacus acuminatus Stokes 1885a, p. 183 Pl. 88, Fig. 4 Cells suborbicular in outline, broadly rounded posteriorly, with a short, blunt apiculation; periplast longitudinally striated; paramy- lon bodies 1-2 ring-like discs; cells 20-22 in diameter, 23-25, long. Plankter; in cedar swamp. Wis. [ 396 ] Phacus acuminatus var. Drezepolskii Skvortzow 1928, p. 113 [P. caudatus Ehrenberg ex Pochmann 1942, p. 146] Pl. 88, Figs. 17, 18 Cells ellipsoid or ovoid, slightly produced posteriorly, sometimes with the cell margins convolute, forming a short, sharp caudus; periplast longitudinally striated; paramylon bodies 2 large discs; cells 10-15, in diameter, 21-24, long. In swamps and ditches. Wis. Phacus alatus Klebs 1883, p. 312 Cells very broadly ovoid to nearly circular in outline, with a short caudus which is strongly curved and twisted to the left (when the cell is seen in ventral view); periplast longitudinally striated; para- mylon bodies 2 large plates or rings which are at least 14 the cell body in length, lateral and sometimes peripheral, one on either side of the cell; cells (16)-19-22 in diameter, 19-24, long. In a slough; among dense growths of filamentous algae. Wis. Phacus anacoelus Stokes 1888, p. 91 Pl 87, Figs: 7, 6; Plr3s, Fig: 1 Cells broadly ovoid, narrowed abruptly posteriorly to form a short caudus, which turns to the left (as seen in ventral view); paramylon bodies 1-2 circular plates; lateral margins of cells with 2-3 creases or folds, the membrane convex between the indentations; periplast longitudinally striate; cells 32-36-(40) in diameter, 40-48, long. Euplanktonic and tychoplanktonic. Wis. Phacus anacoelus var. undulata Skvortzow 1928, p. 109 [Phacus undulatus Pochmann 1942, p. 191] Pl, 87, Figes Cells broadly ovoid, produced posteriorly into a long (or short) sharply pointed caudus, oblique to the longitudinal axis of the cell, anteriorly broadly rounded but slightly bilobed because of the gullet groove; periplast longitudinally striated; margin of the cell with 2-3 bulges; 1 large centrally located paramylon disc; cells 60-65, in diameter, 80-111, long. Our specimens average much larger than the dimensions recorded for this variety, but otherwise they are in agreement. Planktonic; also found in swamps and ditches. Wis. [ 397 ] Phacus anacoelus var. undulata fa. major Prescott 1944, p. 366 PI. 89, Fig. 20 Cells broadly ovoid; ending posteriorly in a long obliquely directcd caudus; margins of cell with a deep crease on either side, forming 2 broad bulges; cells much larger than in the typical form, 64y in diameter, 111-115, long. Euplankter. Wis. Phacus asymmetrica Prescott 1944, p. 366 Pl. 88, Fig. 19 Cell irregularly ovoid-fusiform and slightly spiral in the posterior and anterior portions; extended into a curved, bluntly-pointed cau- dus posteriorly; narrowed anteriorly and with 2 irregular bulges on either side of the apex; periplast finely striated longitudinally; para- mylon bodies 2 thick twisted rings, usually lying transversely in the cell; chloroplasts numerous small ovoid discs; cell 22-25, in diam- eter, 50-53, long. This species should be compared with Phacus Raciborski Drez., which is much more slender and more nearly symmetrical. In a roadside fosse. Wis. Phacus Birgei Prescott 1944, p. 367 Pl. 87, Fig. 11 Cell broadly ovoid, produced posteriorly to form a long tapering caudus which is oblique to the longitudinal axis of the cell, broadly rounded anteriorly; flagellum as long as the cell; periplast very finely striated; margins of the cell sharply notched with 4 small indentations on either side; paramylon bodies 1 large and numerous small circular plates; chloroplasts many ovoid discs; pigment-spot (?); cell 50-60, in diameter, 70-80, long. In a small pond near Genoa City, Wisconsin. Phacus caudatus Huebner 1886, p. 5 Pl. 87, Fig. 13 Cells ovoid-pyriform, spirally twisted, produced posteriorly to form a straight, sharp caudus; broadly rounded anteriorly; periplast longitudinally striated; 1 large, disc-like paramylon body; cells 15-27, in diameter, 30-50y long. Euplanktonic and tychoplanktonic. Wis. Phacus caudatus var. ovalis Drezepolski 1925, p. 266 Pl. 88, Fig. 18 Cells elongate-ovoid, with a short, blunt caudus; cells 18.54 in diameter, 33.3» long; periplast smooth (?). With the typical form. Wis. [ 398 ] Phacus chloroplastes Prescott 1944, p. 367 Pl. 87, Figs. 15, 16 Cells broadly pyriform; produced posteriorly to form a straight or very slightly deflected caudus; broadly rounded anteriorly, with a median papilla; periplast longitudinally striated; margin of the cell entire; chloroplasts several parietal bands lying parallel with the long axis of the cell; paramylon bodies 2 large thin rings or slightly twisted bands lying lengthwise in the cell; eye-spot median, in the apical region; cell 20-22, in diameter, 29-31, long. This form should be compared with P. hispidula (Eichw.) Lemm. Plankter; from an inlet of Trout Lake, Wisconsin. Phacus chloroplastes fa. incisa Prescott 1944, p. 386 Pl. 88, Figs. 5-8 Cells pyriform or napiform in outline, tapering abruptly to a long, straight sharp caudus; periplast longitudinally striated; margin of the cell with 2 sharp notches on either side; cells 25-26p in diam- eter, 38—40p long. In cedar swamp. Wis. Phacus crenulata Prescott 1944, p. 368 Pl. 88, Fig. 9 Cells ovoid-pyriform, posteriorly extended to form a gradually tapering, sharp-pointed caudus; anterior end broadly rounded but bilobed, with a convex papilla between the lobes; flagellum as long as the cell or a little longer; margins of the cell distinctly crenulate or undulate; periplast longitudinally striated with undulating lines; paramylon bodies 2 circular discs; cells 14-15 in diameter, 34-36, long. This species should be compared with P. costata Conrad, which has spiral entire striations rather than longitudinal wavy ones. The anterior end is different in that species also. P. setosa var. crenata Skv. has spiral striations. Plankter; in a cedar swamp. Wis. Phacus curvicauda Swirenko 1915a, p. 333 Pl. 87, Fig. 14; Pl. 88, Fig. 21 Cells broadly ovoid to suborbicular in outline, slightly spiral in the posterior part, which is extended into a caudus that curves obliquely to the left (when viewed from the ventral side); anterior end broadly rounded; periplast longitudinally finely striated (or [ 399 ] smooth ?); paramylon bodies 2 large discs; chloroplasts numerous ovoid bodies; cell 24-26y in diameter, (25)-—28-30, long. Euplanktonic and tychoplanktonic. Wis. Phacus helikoides Pochmann 1942, p. 212 Pl. 87, Fig. 9 Cells fusiform or elongate fusiform-pyriform, twisted’ throughout their entire length (sometimes closely so), briefly narrowed anter- iorly and bilobed, the lobes appearing in 2 planes when seen from the side; tapering posteriorly to a spirally twisted, long, straight caudus which is about 1% the cell body in length; margins of the cell entire but with 2 or 3 bulges; periplast longitudinally and spirally striated; 1 large circular paramylon body; cells 39-(40)—54» in diameter, 70-120, long. This species should be compared with P. tortus (Lemm.) Skv., which is broader and is twisted only in the posterior portion of the cell. Not uncommon in the plankton of lakes and ponds but most frequently found in the tychoplankton of shallow water. Wis. Phacus Lemmermannii (Swir.) Skvortzow 1928, p. 114 Pl. 88, Fig. 12 Cells broadly ellipsoid to ovoid, decidedly twisted in the posterior portion (usually) and somewhat abruptly tapered to a short, sharp caudus which turns to the right (when the cell is seen from the ventral side); slightly retuse at the anterior pole and sometimes rather narrowly rounded (in our specimens); paramylon bodies either 2 moderately large rings or, more commonly, 2 larger rings and many small circular plates; cell (19)-20-30, in diameter, (27 )-32-45-( 47) » long. Plankter; in sloughs and ponds. Wis. Phacus longicauda (Ehrenb.) Dujardin 1841, p. 337 Pl, 37, Fig. 1 Cells broadly ovoid to pyriform, tapering gradually posteriorly to form a long, straight, sharply pointed caudus; anteriorly broadly rounded; periplast longitudinally striated; flagellum shorter than the cell in length; paramylon body usually in the form of a single large (or small) circular plate; cells 45-70» in diameter, 85-170n long. ace common in the euplankton and tychoplankton of lakes and swamps. Mich., Wis. [ 400 ] Phacus Nordstedtii Lemmermann 1904, p. 125 Pl. 88, Fig. 1 Cells napiform, nearly spherical but with a long, straight, sharply pointed caudus; broadly rounded anteriorly; periplast forming an envelope widely separated from an elliptical protoplast, the periplast spirally striated; paramylon bodies not observed; chloroplasts num- erous ovoid indistinct discs; cells 18.54 in diameter, 36, long. Our specimens are assigned here because of the cell shape and periplast characteristics. Judging from the original description of P. Nordstedtii, it was not clear to the author of the species whether the species actually belonged to Phacus. Our specimens are much smaller than the dimensions given for this species and perhaps should be described as a new variety. This shouild be deferred, however, until more is learned of their cytology. Plankter; from a cedar swamp. Wis. Phacus orbicularis Huebner 1886, p. 5 Pl. 87, Fig. 10 Cells orbicular in outline, with a short caudus curved to the right (when seen in ventral view); broadly rounded anteriorly; periplast finely striated longitudinally; flagellum as long as the body; para- mylon bodies 2 disc-shaped plates; cells 39-45, in diameter, 60—70- 100, long. Plankter; from a cedar swamp. Wis. Phacus orbicularis var. caudatus Skzortzow 1928, p. 112 [P. platalea Drezepolski ex Pochmann 1942, p. 179] Pl. 87, Fig.12; Pl. 88, Fig. 15 Cells broadly ovoid to nearly round in outline, spirally twisted, extended posteriorly into a long, straight, sharply pointed caudus; periplast longitudinally striated; paramylon bodies 1-2 (sometimes several) large circular plates; cells 45-47, in diameter, 65-69, long. With the typical form in a cedar swamp. Wis. Phacus orbicularis var. Zmudae Namyslowski 1921 [P. circulatus Pochmann 1942, p. 177] Pl. 88, Fig. 10 Cells orbicular in outline, produced posteriorly to form a short caudus obliquely turned to the left (as seen in ventral view); peri- plast longitudinally striated; cells 18.5-21 in diameter, 27-29 long. In a roadside fosse. Wis. [ 401 ] Phacus pleuronectes (Muell.) Dujardin 1841, p. 336 Pl. 88, Fig. 16 Cells broadly ovoid to suborbicular in outline, slightly spiral and produced posteriorly to form a stout, sharp-pointed caudus which is obliquely turned to the right (when seen from the ventral side); anterior end broadly rounded; periplast longitudinally striated; flagellum as long as or longer than the body; paramylon bodies 1-2 ring-like discs; cells (30)-37-46.8-(50)u in diameter, (42)- 50-80—( 100) » long. This is a common species in marginal waters of eutrophic lakes, especially where protected from wave action; also frequent in ponds and ditches. Mich., Wis. Phacus pseudoswirenkoi Prescott 1944, p. 368 Pl. 85, Fig. 26; Pl. 87, Fig. 2; Pl. 88, Fig. 14 Cells orbicular in outline, abruptly narrowed posteriorly and produced to form a short, sharp caudus which curves to the left (when seen from the ventral side); anterior end broadly rounded; flagellum about as long as the body; periplast longitudinally striated, with a deep, sharp, lateral notch medianly located on the right side (rarely one on the left side also); paramylon body a large, circular plate; cells 30-33» in diameter, 37-40, long. This species should be compared with P. Swirenkoi, a species which is about the same size but which has entire margins and a caudus which turns to the right. Plankter; from a cedar swamp; in ponds and ditches. Wis. Phacus pyrum (Ehrenb.) Stein 1878, III, Taf. 19, Figs. 51-54 Pl. 88, Fig. 22 Cells ovoid, narrowed gradually posteriorly to a long, straight, finely pointed caudus; broadly rounded anteriorly, but with 2 pa- pillae between which the flagellum emerges; periplast spirally ribbed; paramylon bodies 2 ring-like plates, laterally situated; cells (7)-15.6-21 in diameter, 27-30, long. Euplanktonic and tychoplanktonic. Mich., Wis. Phacus Segretii Allorge & Lefevre 1925, pp. 128, 129 Cells broadly ovoid or unsymmetrically orbicular in outline, with- out a caudus; slightly narrowed anteriorly, with a prominent ventral furrow; broadly rounded posteriorly; periplast longitudinally or slightly spirally striated; paramylon bodies in the form of 1 large and 1 smaller circular plate; cells 20-22» in diameter, 22—28p long. Typical form not observed in our collections. [ 402 ] Phacus Segretii var. ovum Prescott 1944, p. 369 Pl. 88, Fig. 23 Cells larger than in the typical form, broadly ovoid; 28-30» in diameter, 39-41, long. In swamps. Wis. Phacus Spirogyra Drezepolski 1925, pp. 234, 267 Cells unsymmetrically spherical or ovoid, with a sharply pointed caudus arising from the broadly rounded posterior; periplast spirally striated with rows of granules; cells 32, in diameter, 45, long, caudus 10, long. Typical form not observed in our collections. Phacus Spirogyra var. maxima Prescott 1944, p. 369 Pl. 87, Figs. 4-6 Cells ovoid to somewhat oblong, unsymmetrically spiral or merely twisted once, abruptly narrowed posteriorly into a long straight or curved caudus; broadly rounded anteriorly (narrowly rounded when seen from the side), with a prominent median protrusion; periplast longitudinally striated with spiral rows of granules; chloroplasts numerous discs; paramylon bodies 2 large doughnut-shaped rings; cells 35-40, in diameter, 70-80, long. This species is peculiar in the shape of the cell body which is not very much flattened. In side view it is narrower than when seen from the front. In a roadside fosse. Wis. Phacus suecicus Lemmermann in Pascher & Lemmermann 1913, p. 139 Pl. 88, Figs. 2,3 Cells broadly ellipsoid or ovate, but not quite symmetrical, with a relatively long, sharp caudus which is slightly deflected; truncate or slightly retuse at the anterior end but with a prominent, median, collar-like papilla through which the flagellum extends; flagellum as long as the cell body; cell planoconvex when seen from the side; periplast longitudinally striated with rows of sharp granules; chloro- plasts numerous circular discs; paramylon bodies 2 lateral and peripheral plates or rods lying just within the periplast; cells (14)- 19-22, in diameter, 34-36, long, 6-11, thick. Plankter; in a cedar swamp. Wis. [ 403 ] Phacus Swirenkoi Skvortzow 1928, p. 114 Pl. 88, Fig. 24 Cells orbicular in outline, slightly twisted posteriorly and extended into a short, sharp caudus which turns obliquely to the right (when seen from the ventral side); broadly rounded anteriorly; periplast longitudinally striated; margin of the cell entire; paramylon bodies 2 large circular plates; cells 35y in diameter, 48—46y long. Common in the plankton of lakes; in tychoplankton of bays and in swamps. Wis. Phacus tortus (Lemm.) Skvortzow 1928, p. 110 Pl. 88, Fig. 20 Cells broadly fusiform or napiform, broadest in the anterior third of the cell, conically rounded at the anterior end, tapering and spirally twisted in the posterior portion to form a long, straight (rarely slightly curved) caudus; periplast with spiral striations; paramylon bodies 1 or 2 large, centrally located circular plates; flagellum 24 the length of the cell body; cells (38 )—40-50-(52) » in diameter, 85-95-(112) » long. In shallow water of many swamps and in small ponds. Wis. Phacus triqueter (Ehrenb. ) Dujardin 1841, p. 338 Pl. 107, Figs. 4-6 Cells broadly ovoid, usually broadest below the median line, broadly rounded and bilobed anteriorly, narrowed unsymmetrically posteriorly to form a prominent, slightly deflected, sharply pointed caudus; the dorsal surface with a high flange, thus making the cell triangular in outline when seen from the end; a deep longitudinal furrow on the ventral side; periplast longitudinally striated, the striations extending slightly into the caudus; paramylon bodies 2 to several large rings (sometimes only 1); cells 30-45, in diameter, 37-68» long. Tychoplankter. Wis. LEPOCINCLIS Perty 1849, p. 28 Cells ovoid, ovate, elliptical or fusiform, sometimes nearly spheri- cal, with a firm and usually spirally striated periplast, round in cross section; posteriorly extended into an abruptly pointed tail-piece (rarely gradually tapering); a gullet in the anterior end where there arises a single flagellum that is once or twice the cell in length; chloroplasts numerous parietal discs; pigment-spot laterally placed [ 404 ] in the anterior region; reserve food in the form of 2 large, lateral paramylon rings, the 2 together sometimes nearly encircling the cell. Species of this genus are usually found in company with other euglenoids. They are, for the most part, not found in euplankton but occur among dense growth of algae in shallow bays, swamps, and in ponds. They nearly always appear in samples from water which is rich in organic acids and nitrogenous substances. The nature of the periplast decoration is of taxonomic value because it varies according to species. This character is often ob- scured by the density of cell contents, and it is necessary to manipu- late a specimen so that it can be seen from various angles. Key to the Species 1. Cells narrowly pyriform or narrowly ovoid, oragtially wtapering, MOStETIOTLY® Site en. Fe L. acuta 1. Cells broadly ovoid, or broadly ellipsoid, Wwitla@utwa lomGCatichis =e aepes net © 50) che cd 1h es ee ee 2 2. Cells ovoid, 39-58u long, with a short caudus L. fusiformis var. major 21 (Gellsisubplobese, ovoid; or! fusiform; ‘smaller 2S ea ee 3 8. Cells with a bipapillate protrusion at the anterior end: trou which the fagelluny emergesi 22 4 a: Cellsswithout; a. bipapillate protrusion 3 = = ee ee 5 4, Cells broadly ovoid, 19-21 in diameter_._____________ L. glabra 4. Cells ellipsoid, or narrowly ovoid, 8-104 in diameter_______ L. sphagnophila sells: iis li(jcwunciarmietet se sie Fv ES te 9 ee L. fusiformis Ba Cells largery, 22-30 inidiameter 2 oe oie oe 8 es ee es 6 6. Cells 22—25u in diameter; flagellum emerging aie (oven inudetalore Clateluoetn Sy Meh is FT ee See St eee re ee ee Ree ee L. ovum 6. Cells 28—30u in diameter; flagellum arising subapically;to nearly Naterally, 0 ee L. Playfairiana Lepocinclis acuta Prescott in Prescott, Silva, & Wade 1949, p. 89 Pl. 89, Figs. 8, 9 Cells ovoid-pyriform, tapering posteriorly to a long, sharply point- ed caudus, slightly narrowed anteriorly and rounded at the apex; periplast spirally striated downward to the right; flagellum about as long as the body; paramylon in the form of 2 curved plates, 1 on either side of the cell; chloroplasts several ovoid discs; cells 11-13, in diameter, 30-34» long. Conrad in his’monograph (1934) does not record any species which combine the characteristics of our specimens. The size of the cell and the long, tapering caudus are distinctive. Among other algae in a fosse. Wis. - [ 405 | Lepocinclis fusiformis (Carter ) Lemmermann 1901, p. 89 Pl. 89, Figs. 1-4 Cells broadly fusiform or pyriform, slightly produced posteriorly to form a blunt basal point; membrane spirally striated; paramylon bodies 2 to several circular plates; flagellum about as long as the cell; 15-17 in diameter and up to 36, long. In a roadside fosse. Wis. Lepocinclis fusiformis var. major Fritsch & Rich 1930, p. 72 Pl. 89, Figs. 7, 15 Cells elongate-ovoid to subfusiform, broadest below the midregion, produced posteriorly into a very short obtuse tail-piece; usually with a bipapillate protrusion at the anterior end; periplast sometimes with extremely fine spiral striations (almost straight in our speci- mens); paramylon bodies 2 very large oval rings, sometimes over- lapping one another; chloroplasts numerous irregularly shaped discs; cells 25-29-(39) in diameter, 39-58, long. This variety is originally described as having, at times, many small paramylon bodies, but our specimens showed only the large rings. The periplast is very faintly striated, a character seen only under favorable conditions. This species should be compared with L. Steinii Lemm. and L. costata Playf. These species are somewhat similar in shape but differ in size and details of the periplast fea- tures, as well as in the form of the paramylon bodies. Tow from a small pond. Wis. Lepocinclis glabra Drezepolski 1925, p. 269 Pl. 89, Fig. 14 Cells broadly ellipsoid or ovoid, broadly rounded posteriorly but with a short, blunt caudus; very slightly narrowed anteriorly, with a bipapillate protrusion through which the flagellum arises; flagellum about as long as the body; periplast smooth (?); paramylon in the form of 2 very large, curved plates, one on either side and in certain positions appearing as 4 plates; cells 19-21, in diameter, 25-31, long. In a roadside fosse. Wis. Lepocinclis glabra fa. minor Prescott 1944, p. 370 Pl. 89, Fig. 10 Cells broadly ovoid, with a short papilla-like caudus, broadly rounded anteriorly and ending in a bipapillate protrusion through which the flagellum emerges; flagellum about as long as the body; periplast smooth; paramylon in the form of 2 semicircular bands, [ 406 ] curving transversely at the periphery of the cell, one on either side; chloroplasts numerous, oval discs; cells 14-16 in diameter, 20-22y long, smaller than the typical form. In a tow sample from a cedar swamp. Wis. Lepocinclis ovum (Ehrenb.) Lemmermann 1901, p. 88 Pl. 89, Figs. 5, 6 Cells broadly ovate, with a short, blunt caudus, rounded both anteriorly and posteriorly; periplast spirally striated to the right; flagellum about as long as the body; paramylon in the form of 2 rings, 1 on either side of the cell; cells 22-25y in diameter, 28-30, long. oem in ditches, swamps and small ponds; also found in the shallow water of bays and lagoons among dense growths of algae; rarely euplanktonic. Mich., Wis. Lepocinclis Playfairiana Deflandre 1932, p. 227 Pl. 89, Fig. 16 Cells broadly oval with a short caudus, slightly narrowed and sharply rounded anteriorly, the gullet and flagellum attachment lateral to the apex, where there is a slight invagination on the right side; periplast smooth; paramylon bodies 2 large circular or oval rings; cells 28-30, in diameter, 46-48, long. In tows from swamps and ponds. Wis. Lepocinclis sphagnophila Lemmermann 1904, p. 124 Pl. 89, Figs. 11-18 Cells fusiform or ovoid, narrowed posteriorly into a short caudus, tapering anteriorly and forming a bluntly rounded apex which is bipapillate (in our specimens); paramylon bodies 4 plates, 2 on either side; chloroplasts relatively few ovoid discs; flagellum length (?); cells 8-10» in diameter, 22-25, long. Our specimens are assigned here because of their general agree- ment with Lemmermann’s description. Conrad (1934) reports this as a doubtful or little known species. Not infrequent in soft and acid water habitats. Wis. TRACHELOMONAS Ehrenberg 1835, p. 315 In this genus euglenoid cells are enclosed in a firm gelatinous shell which has an opening for the flagellum. The shell or test has an almost endless variety of shapes and forms of decoration, and since these features are specific the taxonomy of the genus is based [ 407 | upon characteristics of the test rather than on those of the proto- plast. The test is brown, often opaque, or tan to nearly colorless, according to the amount of iron compounds deposited in it. The test may be smooth or decorated with spines, warts, reticulations, punctations, or combinations of these. The protoplast inside is highly metabolic and has the general features of the euglenoids. There is 1 flagellum, a red pigment-spot, and numerous ovoid, disc-like chloroplasts which may have pyrenoids. Reproduction is by cell division, which takes place within the test, one of the new cells escaping through the aperture and secreting its own shell. Although a few species may appear in the euplankton, most species of Trachelomonas occur in shallow water of swamps, ditches, and lagoons as tychoplankters, especially where there is a high con- centration of organic matter and where temperatures are high. The organisms may be so abundant as to color the water brown, although they never form a conspicuous surface film as does Euglena. Key to the Species 1. Test with the flagellum opening in a neck, or Surrounded mibYyieaeCOllan earache urn ee eee See ee 2 1. Test without a neck or collar around the flagellum aperture................ 22 2; Flagellum) opening “in) a> distinct® necks. sts eee ee eee 3 2. Flagellum opening in a collar or thickened ring (*)..0.00.00.00.0ccccc... 12 3. Test globose, with 4 or 5 long, sharp spines.....................00000000-+. T. aculeata 3. West with ‘shorter, more numerous (Spimes .2..0.20). sess. cetosecescveeeseceee ec. 4 4. Test extended into a long, spine-tipped caudus ....................... T. speciosa 4. Test without a caudus, or if present not spine-tipped.......................... 5 5. lest isexangullan-ellipsoid teen e300) se Pe ee eee T. hexangulata Dilest™ some Other” SHAPE. ee ee ee Re I a eae 6 6. Test broadly ovoid, wrinkled and rugose; MECKIBiWisted WORM CURVEC tne YN cen nts cue die cnet ode a eae T. scabra GP lest shaped otherwise; mot. FugOSe!:.6..- 02 eoeeae keene ee ee ee 7 7. Test rectangular-fusiform, margins retuse, extended into a Candis ett A nok eee le be cst. rune Aceh eee aoe rhs pee T T. Girardiana 7. Test some other shape, not extended into a caudus.........0....0..0.0:000000 8 lest a-elongate-ellipsoids. east edi tee koe too ee ee ee 9 Sn Lest; oblong-cylindricor oblong: ee ee ee 10 9. Test with numerous, minute spines, punctate; Warn Of “COMAT PSIMOOEN ; 4-0-5. 00 cesco nm tosesospes ssa ae oases Poe ae T. bulla 9. Test with scattered, stout spines; collar foothed sat thes marginus eee. ee eee et ay eee reas T. sydneyensis 105 Test oval’ to,oblong. collar curveds.cn.2. cl pc euen idee ee T. similis 10. Test some other shape; collar not curved ....................... Peet Rh Ls ll (*) The thickened ring is a variable feature in some species. For question- able forms, follow through both No. 2 choices. [ 408 ] Tests anpularnly* oblong, bottle-shaped 2205. 2.2.-::...0<2-..-----o- 2! T. euchlora . Test oblong-cylindric, lateral margins parallel.........0...00000........... T. dubia . Test beset with long or short spines ...... val hic Gen 0 Ae pe ea A ie 13 . Test without spines; either smooth or with granules or warts................ 16 Wham: Of-collar beset with stout Spimes!s.5 4. Gesclcw.csteelosesdisocrs.:. T. armata EIEIO S ADELEUITE pSTMOOL ce sai a eet. ee er en aa one 14 Milestrovalyewith long-. stout; -spines= 0 este. ssetec.ves cakes T. horrida . Test broadly oval to subspherical, with short spines or sharp warts... 15 15. Test subspherical, beset with sharp warts or very short SIUIINES Fee ee ee SE cs, a eee Ma Rr a T. hispida 15op@est.oval. beset; with ‘stout Spines......221..0. 406-5 se00-p0-one- eee T. charkowiensis 1G abestmsimsaObitt ese) 2s bea ie as OS een ny ae tee acd eee ben U7 16. Test granular, rugose, OT AS PUNY he sf oe hae ne me We) Bn ioreas 20 17. Test with mammillate collar; spherical Sie ee thc aly VER T. mammillosa 17. Test without a mammillate collar; cylindric or ovalis <2 i. 18 1S eaestarcylinvelraeal Mer tort. ee ide oo. «anette Fae Rese Serres sauces onthe T. cylindrica Stes OvAltOnuspuencCal, 22. ees totes... casgeki ut eer As ae cone eee 19 19. Test spherical with an inward projecting flagellar tube........... T. varians 19. Test broadly ellipsoid or oval, with short curved collav.......... T. Playfairii 20. Test oval, (19)—23—25u in diameter, 31—33u lonmemnnitormnly seranilatey ee ey tl ho, cee a) hore tae cee aa ae T. crebea 20. Test ellipsoid to ovoid, smaller, (5)—19u in diameter.................0..0....... 21 21. Test oval, 5—11—17u in diameter, W767 gl Cosa aes On ae a T. pulchella 21. Test ellipsoid, 19a an ‘diameter. 20py, long 7 cc.ccrsapteetesneseee? T. granulosa 22. Test triangular, flagellum aperture occupying the entire ESF ec hace meant Rh ners ORME AREER UR og e PAN PATE OR RORaay ai pimpin Ra amr T. triangularis 22. Test some other SHADE: APeCKEMTE: MATTOWED \ 20.0 c5..5.65- cece esc sateen cosas sete 23 D3e Vhest A cpuentcal mon SUDSPleTICA bls foots sous sete et aastatenees eee eeeste 24 93° Test elongate, ovoid or: cylindrical’... 4 ...04:.3.c%-d.. = G. palustre Glenodinium armatum Levander 1900, p. 103 Pl. 90, Fig. 7 Cells spherical in outline, unsymmetrically divided by a broad, transverse furrow, the epicone longer, almost hemispherical but sharply rounded at the apex; the hypocone short, broadly rounded at the pole and with a short conical projection on the left side (right side as seen from the ventral surface); plates scarcely visible in the thin but firm theca; chromatophores radially arranged ovoid plates; pigment-spot present in the longitudinal sulcus which is hardly visible but which extends from the transverse furrow almost to the posterior pole; cells 19-28 in diameter, 16-29.7, long. Tychoplankter. Wis. Glenodinium Borgei (Lemm.) Schiller 1935-1937, p. 112 [Peridinium Borgei Lemmermann] Pl. 90, Figs. 8, 9 Cells broadly ovoid to subglobose, the epicone high and shortly apiculate; not dorsiventrally compressed but round in polar view; epitheca with 1 apical, 2 intercalary, and 6 precingular plates; the [ 428 ] apical plate on the dorsal side not extending to the apex; hypotheca with 5 postcingular and 2 antapical plates; cells 36-40, in diameter, 4046p. long. Tychoplankter. Wis. Glenodinium Gymnodinium Penard 1891, p. 54 Pl. 90, Figs. 10, 11 Cells broadly oval as seen in the ventral view, dorsiventrally flat- tened as seen vertically; transverse furrow broad, turning spirally to the left; longitudinal furrow extending from the epicone to the apex of the hypocone, the left margin of the longitudinal furrow with a flange which ends in a tooth at the posterior pole; epitheca with 1-(2?) apical, 4 intercalary, and 7 precingular plates; hypo- theca with 5 postcingular and 2 antapical plates; chromatophores brownish-green; cells 35, in diameter, 40, long. Tychoplankter. Wis. Glenodinium Kulczynskii (Wolosz. ) Schiller 1935-1937, p. 96 PI. 90, Figs. 12-14 Cells broadly ovoid or nearly round as seen in ventral view, flattened in polar view, the dorsal margin broadly convex; epitheca with 1 apical, 3 intercalary, and 6 precingular plates; hypotheca with 6 postcingular and 2 antapical plates; longitudinal furrow extend- ing to the apex of the hypocone; cell 30-31.5y in diameter, 35, long. Tychoplankter. Wis. Glenodinium palustre (Lemm.) Schiller 1935-1937, p. 99 [Gonyaulax palustris Lemmermann] Pl. 90, Figs. 15, 16 Cells globose with the transverse furrow slightly but clearly spiral; longitudinal furrow extending from the epicone through the hypocone; epitheca with 1 apical plate, 3 intercalary and 6 precin- gular plates; hypotheca with 5 postcingular and 1 antapical plate; cells 25-30, in diameter, 27-34, long. Plankter; in several, mostly soft water, lakes and acid bogs. Wis. Glenodinium Penardiforme (Linde.) Schiller 1935-1937, p. 113 Pl. 90, Fig. 21 Cells small, ovoid, the epicone sharply rounded and slightly api- culate, dorsiventrally flattened; the hypocone broadly rounded and emarginate at the pole; transverse furrow broad; longitudinal fur- row scarcely extending into the epicone, broadening into the [ 429 ] hypocone and reaching the posterior pole; cells 20-25, in diameter, 30-35p long. The plates are very inconspicuous in the specimens seen and their assignment is questionably made on the basis of present information. G. Penardiforme is described as having 4 intercalary and 6 precin- gular plates in the epitheca, 5 postcingular and 2 antapical plates in the hypotheca; the cell with or without chromatophores. Not uncommon; in several soft water lakes, ponds, and swamps. Wis. Glenodinium pulvisculus (Ehrenb.) Stein 1883, Ill, part 2 Pl. 90, Figs. 17, 18 Cells ovate to subglobose, the epicone and hypocone both broadly | rounded at the poles; transverse furrow winding to the left; longi- tudinal furrow extending into the epicone and posteriorly almost to the pole of the hypocone; chromatophores numerous, golden-brown bodies; cells 13-19-(29) in diameter, 23-35, long. The plates of the theca of this species are as yet incompletely known, and the assignment to the genus Glenodinium is question- able. As suggested by Eddy (1930) it may belong to Gymnodinium. Tychoplankter. Mich., Wis. Glenodinium quadridens (Stein) Schiller 1935-1937, p. 117 Pl. 90, Figs. 19, 20 Cells ovate, the epicone apiculate, the hypocone broadly rounded and furnished with 3-5 short, sharp spines, laterally and posteriorly placed; transverse furrow not spiral, usually median and equally dividing the cell; longitudinal furrow extending into the epicone, widening posteriorly and reaching the apex of the hypocone; epitheca with 1 apical, 5 intercalary, and 7 precingular plates; hypotheca with 5 postcingular and 2 antapical plates with a stout spine on each; cells 20-35, in diameter, 2480p long. Tychoplankter. Wis. HEMIDINIUM Stein 1883,p. 90 Cells unsymmetrically ellipsoid, much flattened dorsiventrally, both poles broadly rounded, the anterior less so and somewhat cone-shaped; transverse furrow incomplete, spirally descending to the left; membrane covered by a very thin theca in which there are indistinctly marked areolate plates; epitheca with 6 apical, 6 precingular plates; hypotheca with 5 postcingular, 1 intercalary, [ 430 ] and 1 antapical plate; chromatophores golden-brown fusiform bod- ies, radially arranged. The plates in this genus can be discerned only under favorable optical conditions. Hemidinium nasutum Stein 1883, p. 91 Pl. 90, Figs. 4-6 Cells elliptical or narrowly ovoid; transverse furrow incomplete, curving down to the right as seen from the ventral side; longitudinal furrow forming a narrow sulcus which extends from the transverse furrow to the posterior pole which is broadly rounded; cell 16-20, in diameter, 24-28, long. Fairly common in the plankton of several lakes, especially in marginal waters among dense beds of other algae. Wis. FAMILY PERIDINIACEAE This family has cells which are globose, or only slightly flattened, fusiform, or top-shaped. The transverse furrow is broad and hori- zontal, definitely dividing the cell into epicone and hypocone. Although usually broadly rounded anteriorly, the epicone may be narrowed and pointed at the apex. The hypocone likewise is usually broadly convex, but in a few forms it may be somewhat produced to form one or more lobes or conical projections. Reproduction is by cell division. Resting cysts of specific shape are used during periods of adverse environmental conditions. PERIDINIUM Ehrenberg 1832a, p. 38 [Peridinium Ehrenb., Stein 1883] Cells globose, ovoid, or fusiform (in fresh-water species ), usually somewhat dorsiventrally flattened, either broadly rounded at the poles or produced to form apiculations or short horns; transverse furrow infra-median and slightly spiral, the epicone sometimes with a true apex and a pore at the anterior pole, or with a false apex that is produced into a horn without a pore and is longer than the hypocone; longitudinal furrow usually broad in the hypocone and extending to the posterior pole, or not, and into the epicone slightly; flagella attached in the ventral sulcus, one winding about the cell in the transverse furrow, the other trailing; arrangement and num- ber of plates in the epitheca variable, usually 4 apical, 3 intercalary and 6-7 precingular plates, one of the apical plates extending from the top of the longitudinal sulcus to the apical pole (the rhomboid or ventral plate); hypotheca with 5 postcingulars and 2 antapical [ 431 ] plates; all plates conspicuously marked with reticular thickenings and sometimes other decorations, such as small spines, and with narrow or wide sutures between the plates which are usually striated, as is also the transverse furrow; in some species with a conspicuous flange or wing-like rim about the cell through which small ribs or concretions radiate to the margin from the surface of the plates. Key to the Species 1. Cells broadly fusiform, extended posteriorly into 1 or more processes. 2 Ti iCells) broadly rounded) posteriorly, 225 228 5S eae ee ee eee 8 (See P. cinctum var. tuberosum, however. ) 2. One posterior horn-like extension_.______-_-_.-_-----.-------------- P. wisconsinense 2. Two: posterior horn-like extensions=+ == Se P. limbatum CE Gell onl Uutancbihoo (elas @ Geet eee Eee ne es ae ee ee 6 SenGelisy lary e ten xe a hk a i ee ol PA ee 4 4.1G@ellsmeanly, cixeularsimpout line sas ee ee eee 5 4 Gellsidistinctlyslonger than broad === ss a eee P. Willei 5. Cells 35-55y in diameter; longitudinal furrow extending for some distance into the epicone______-_______ P. cinctum 5. Cells 55-80u in diameter; longitudinal furrow scarcelya extending into ‘the epiconé: 2-2) P. gatunense 6. Cells with 3 small teeth at the posterior pole___________ P. inconspicuum 6. Cells with broadly rounded smooth antapical poles _________ P. pusillum Peridinium cinctum (Muell.) Ehrenberg 1838, p. 253 P]. 91, Fig. 1-4 Cells globose, subglobose, or broadly ovoid in ventral view, very slightly flattened dorsiventrally as seen in polar view; transverse furrow broad, spiral, dividing the cell almost equally on the left side (as seen ventrally) but spiralling to a supramedian position on the right; plates thick and coarsely reticulate; epicone high and broadly rounded, epitheca with 4 apicals (including the rhomboid plate), 3 intercalary, and 7 precingular plates; hypocone broadly rounded posteriorly, hypotheca with 5 postcingular and 2 antapical plates; cells 35-55, in diameter, 40-60, long. Fairly common in both euplankton and tychoplankton. Mich., Wis. Peridinium cinctum var. Lemmermannii G. S. West 1909, p. 190 Cells 62-70 in diameter, 56-70» long, 52-53, thick; a variety in which the right antapical plate is distinctly larger than the left. Euplanktonic and tychoplanktonic. Mich., Wis. [ 432 ] Peridinium cinctum var. tuberosum (Meunier ) Lindemann 1928, p. 260 Pl. 91, Figs. 7-12 A variety larger than the typical, 63» in diameter, 66.6, long, and more nearly globose, scarcely if at all dorsiventrally flattened; in ventral view the epicone broadly rounded in general outline, with angulations at the margin where it is interrupted by the sutures of the plates, sometimes apiculate at the pole; plates variable, usually with 4 apical, 3 intercalary, and 7 precingular plates; the 2 hypothecal plates produced posteriorly to form 3 stout, blunt horns (the variety is described as having 3 antapical plates, but Wisconsin specimens seem to have but 2 in every case); the cell showing a flange that extends from the transverse furrow around to the poles; plates coarsely reticulate. Tychoplankter; in ponds and swamps. Wis. Peridinium gatunense Nygaard in Ostenfeld & Nygaard 1925, p. 10 (reprint) Pl. 90, Figs. 25, 26 Cells globose to elliptic, with angulations at the marginal sutures; (as seen ventrally), the poles broadly rounded; transverse furrow spiral with a wide border, unequally dividing the cell into a greater epicone and a shorter hypocone; the longitudinal furrow extending from high in the epicone to near the posterior pole; plates with wide, striated sutures between them, coarsely reticulate; epitheca with 13 plates; hypotheca with 2 large antapicals and 5 postcingular plates; cells 55-80, in diameter, 45-80, long. Tychoplanktonic and euplanktonic. Wis. Peridinium inconspicuum Lemmermann 1900, p. 350 Pl. 90, Figs. 22-24 Cells small, ovoid, with the apical region slightly produced and pointed, the posterior pole broadly rounded with 2 or 3 short, sharp, horn-like projections; in polar view slightly flattened dorsiventrally; transverse furrow broad, without a marginal ridge, or with a very narrow one (although the furrow is very deep), not spiral, dividing the cell into a tall epicone and a short hypocone; longitudinal furrow very broad in the hypocone, extending from the posterior pole into the epicone a short distance; epitheca with 13 plates and a true apex; hypotheca with 2 large antapical and 6 postcingular plates; cells 18.5-20, in diameter, 22-25, long. The plants are small and the plate characteristics are seen with difficulty unless empty cells are found. This species often appears in [ 433 ] great numbers, although it is less widely distributed than some other species of Peridinium in our collections. Several of the described varieties have been noted in our collections, but according to Schiller (1935) these should be referred to the typical form and the varietal names not retained. Plankter; found in several, especially soft water, lakes and in desmid habitats. Wis. Peridinium limbatum (Stokes) Lemmermann 1900c, p. (120) Pl. 91, Figs. 16-18 Cells ovate, the epicone narrowed and produced to form a promi- nent apiculation which is bifurcate and often turned to the left when viewed from the ventral side; hypocone broad, with 2 stout posterior horns; transverse furrow broad, slightly spiral, unsymmetri- cally dividing the cell into a high epicone and a short hypocone; longitudinal furrow very broad in the hypocone, extending from the posterior pole to well within the epicone; rhomboid plate extend- ing from the top of the longitudinal furrow to the apical pole, which has a true apex and pore; epitheca with 10 plates; hypotheca with 5 (?) postcingulars and 2 antapical plates (these two produced to form the posterior horns); sutures and transverse furrow striated; plates reticulate; cells 60-65, in diameter, 80-85.5 long. Rare; in the plankton of soft water lakes and in Sphagnum bogs. Wis. Peridinium pusillum (Penard) Lemmermann 1901d, p. 65 Pl. 107, Figs. 7-9 Cells ovoid, somewhat flattened dorsiventrally, the epicone slightly longer than the hypocone so that the transverse furrow is inframedian, and not spiral; epitheca slightly produced at the apex and emarginate, with 7 precingular and 6 apical plates; hypotheca with 5 postcingular and 2 antapical plates; chromatophores golden- brown; 13-20y in diameter, 18-24, long. Mich. Peridinium Willei Huitfeld-Kaas 1900, p.5 Pl. 91, Figs. 22-25 Cells large, subglobose, very little compressed dorsiventrally, broadly rounded at both poles, with a wing-like flange which forms a crest anteriorly and two lobes posteriorly, and with raised edges along the margins of the sutures of the plates (especially in mature cells); transverse furrow broad, spiral, dividing the cell unsymme- trically into a high epicone and a short hypocone, with a wide border that often extends down along the edge of the longitudinal [ 434 ] furrow, producing a wing-like flange; longitudinal furrow broad in the hypocone, extending into the epicone from the posterior pole; rhomboidal plate broadly wedge-shaped, widest at the top and reaching from the margin of the longitudinal furrow to just below the anterior pole where there is not a true apex; epitheca with 14 plates, 7 precingulars, 3 apicals (median), 2 ventral apicals, 1 dorsal apical, and a rhomboidal plate; hypotheca with the usual arrange- ment of 5 postcingular and 2 large antapical plates; cell 49-55 in diameter, 50—70y long. Plankter; in a variety of lakes; widely distributed but seldom occurring in abundance. Wis. Peridinium wisconsinense Eddy 1930, p. 300 Pl. 91, Figs. 13-15 Cells large, spindle-shaped, slightly flattened dorsiventrally when seen from the poles; epicone greatly produced to form a prominent cone and the hypocone likewise produced to form a single, stout sharply-pointed horn; transverse furrow broad, slightly spiral (in our specimens, but described as strongly spiral), almost equally dividing the cell into conical epi- and hypocones; longitudinal fur- row extending from about half way to the posterior pole to the transverse furrow but not into the epicone; rhomboidal cell ex- tending from the top of the longitudinal furrow to the apical pole which has a true apex; epitheca with 14 plates (including the rhom- boidal), 1 median apical, 2 ventral apicals, 1 right lateral apical (on the left as seen from the top), and 2 dorsal apicals; hypotheca with 5 postcingular and 2 antapical plates, one of which (left, as seen from the posterior pole) forms the posterior horn; plates coarsely reticulate; cells 48-56u in diameter, 55-64, long; cyst broadly ovoid with one pole sharply and the other bluntly pointed, the membrane thick and lamellate at the poles. Originally described from Lake Oconomowoc, Wisconsin. Common in a variety of lakes; frequently abundant in favorable habitats. Mich., Wis. FAMILY CERATIACEAE This family (erected for the genus Ceratium) has cells which are fusiform in general outline. As described below, there is a prominent apical horn in the epicone and 2-3 posterior horn-like processes in the hypocone. The longitudinal sulcus is very broad and short. The cell undergoes division in such a way that one of the new protoplasts inherits 4 apical, 2 precingular and three post- cingular plates, while the other portion retains the remaining 2 [ 435 ] precingular, the 2 antapical and 2 postcingular plates. This means that the plane of division and separation of plates is oblique. The daughter protoplasts continue to move about and gradually build in the necessary complement of plates. CERATIUM Schrank 1793, p. 34 In this genus there are broadly fusiform cells which have 3 or 4 horns, one anterior and 2 or 3 posterior. The epivalve of the theca (broad just above the girdle) soon narrows abruptly to form the apical horn, which is composed of 4 plates. The hypotheca has 5 postcingular and 2 antapical plates, the latter forming the longest posterior horn. In forms which have 3 posterior horns, one is very short. There are no broad sutures between the plates as in some of the related genera. The transverse furrow opens into a broad longi- tudinal sulcus. The entire theca is uniformly marked with a fine reticulum, the meshes of which are 5- or 6-sided. There are numer- ous brown disc-like chromatophores which are often obscured by the semi-opaqueness of the theca. Most species of Ceratium are marine but there are a few fresh- water plankters, usually occurring more abundantly in hard water than in soft water lakes. Key to the Species 1. Apical horn long and tapering, as long as or longer than the cell body and! the posterior homs — 2-2 C. hirundinella 1. Apical horn shorter than the remainder of the cell 2 2. Apical horn sharply curved and tapering (OV evel OVPUN © 0,0) 00) ¢ Meee en eee C. carolinianum 2. Apical horn straight but directed at an angle from the longitudinal axis; squarely truncate at the apex C. cornutum Ceratium carolinianum (Bailey) Jorgensen 1911, p. 14 [C. curvirostre Huitfeldt-Kaas] PI. 92, Figs. 2,3 Cells broadly fusiform in outline; epivalve broad above the transverse furrow, narrowed abruptly to form a stout, curved apical horn, with a shoulder on each side at the base; transverse furrow relatively narrow; hypotheca broad, with a short diverging horn on the left (as seen from the ventral surface), and a longer central horn which is somewhat obliquely directed; cells 65-80, in diam- eter, about twice as long as broad. Plankter; in Sphagnum bogs, ponds and ditches. Wis. [ 436 ] Ceratium cornutum (Ehrenb.) Claparede & Lachmann 1858, p. 394 Pl. 92, Figs. 8,9 Cells broadly fusiform in outline, stout, the epitheca broad above the transverse furrow, the sides rapidly converging and narrowed to form a short, stout anterior horn which extends obliquely and is truncate at the apex; transverse furrow relatively broad; hypotheca broad below the furrow, extended into 2 horns, 1 short lateral horn and 1 longer and median; cells 75-SO» in diameter, about as long as wide, or slightly longer. Rare; in the plankton of soft water lakes. Mich., Wis. Ceratium hirundinella (O. F. Muell.) Dujardin 1841, p. 377 Pl. 92, Figs. 4,5 Cells broadly or narrowly fusiform in outline, depending upon the degree of divergence of the horns; very much flattened dorsi- ventrally; epitheca with sharply converging margins from just above the transverse furrow, then narrowed more gradually to form a long horn; transverse furrow relatively narrow; body of the hypotheca broad and short below the transverse furrow, divided into a varying number of posterior horns, usually 3, sometimes only 1, the central or median horn the longest and formed by the antapical plates; plates coarsely reticulate; cells varying in size depending upon environmental conditions, 100-400, long. This species is very common, especially in hard water lakes, where occasionally it may become so abundant as to color the lake a deep brown. Such blooms develop and disappear suddenly. This species shows a great variation in the form of the cell, num- ber of horns, etc., and it is often the subject of ecological and limnological studies. It shows a remarkable periodicity and may exhibit a vertical distribution which is accompanied by some inter- esting relationships between the length of the horns and buoyancy; form of the cell and temperature, etc. The tremendous amount of nitrogen, phosphorus, and products of photosynthesis which accumulate in these organisms when they develop a bloom must certainly produce interesting limnological effects in a lake. In spite of the wealth of literature on this genus, very little seems to have been published on the role that these species play in lake biology. Mich., Wis. ORDER DINOCOCCALES These are forms which are not motile in the vegetative state and which are incapable of cell division. They exist as either free- [ 437 ] floating or sedentary attached unicells of various forms, crescent- shaped, quadrangular, or pyramidal, with the angles extended into horns or spines. Usually the wall is thick and shows lamellations where it is thickened at the poles or angles. Many have an expression similar to the encysted phase of the motile Peridiniales. In their reproductive methods the Dinococcales employ autospores or zoo- spores. There are 2-8 of these formed in a cell. In some forms the zoospores show a transverse furrow and other Gymnodinium fea- tures. The spores, upon escape, enlarge and assume the expression of the nonmotile parent cell. One family is recognized. FAMILY DINOCOCCACEAE Characteristics as described for the order. Key to the Genera i} Cells: free-toating.. lunate or arcuate,— = sss ae Cystodinium 1. Cells attached, transversely ellipsoid or inversely buaugularsneiront view ee eee 2) 2. Cells triangular or tetrahedral (especially when SEER TOMIADOVE)* aes ae ne To ea ee Tetradinium 2 Cells tellipsoid 2-5! a .2) 2 esa Raciborskia CYSTODINIUM Klebs 1912, pp. 384, 442 Cells free-floating, lunate or arcuate, the poles extended to form sharp, usually recurved spines; longitudinal and transverse furrows lacking, although the position of the furrows is represented in the swarmers formed by the division of the protoplast within the parent cell; chromatophores several to many, brown, more or less pointed or fusiform discs; nucleus conspicuous and centrally located, pig- ment-spot usually lacking. Key to the Species 1. Cells broadly crescent-shaped, the outer margin broadly convex, the mmer slightly tumidionsteighie = C. iners 1. Cells narrowly crescent-shaped, the outer margin convex, the inner margin concave (sometimes straight in the midregion) 2 2. Each pole of the cell ending in a curved spine which is twisted away from the longitudinal axis of the cell *cellsiGo U0 long seen Sh ee ee C. Steinii 2. Each pole of the cells ending in a spine, 1 straight, the other twisted away from the longitudinal axis of the cell cells| 40-60 .vlong = C. cornifax Cystodinium cornifax (Schill.) Klebs 1912, pp. 384, 442 Pl. 91, Figs. 5, 6 Cells lunate, the dorsal margin strongly convex, the inner margin concave (slightly straight in the midregion); poles extended into [ 438 ] colorless, somewhat twisted horns, one of which is recurved and is directed at an angle from the longitudinal axis; protoplast forming 2 (or only 1) Gymnodinium-like swarmers which have a wide trans- verse furrow, dividing the zoospore into a broadly rounded anterior portion and a broadly conical or sharply pointed posterior, with pigment-spot showing in the longitudinal furrow; cells 28-36y in diameter, 40-60, long (sometimes longer); swarmers about 20 in diameter, 25, long. In the tychoplankton of several lakes and swamps; frequently found in desmid habitats. Wis. Cystodinium iners Geitler 1928a, p.5 Pl. 91, Figs. 19-21 Cells crescent-shaped, strongly convex on the dorsal margin, tumid (or straight) on the ventral or inner margin, ending in sharp points at the poles, with the wall much thickened at the base of the horns, which are in the same plane with the longitudinal axis of the cell; protoplast usually showing a transverse furrow, appearing as a Gymnodinium-like cell dividing to form two swarmers; chromato- phores numerous ovoid plates; cells 25-28-(30) in diameter, 60-80p long, including the apical spines. Mich., Wis. Cystodinium Steinii Klebs 1912, pp. 382, 442 PI. 93, Figs. 1, 2 Cells crescent-shaped, the dorsal margin more strongly convex than the ventral; apices terminating in curved and slightly twisted points, each projecting at a different angle from the longitudinal axis of the cell; upon dividing producing 2 Gymnodinium-like swarmers with a broad transverse furrow and with both poles broadly rounded; pigment-spot in the longitudinal furrow; cells 25-35 in diameter, 65-100-(110), long; swarmers 30-35, wide, 40-50, long. Rare; in the tychoplankton of lakes and acid swamps. Mich., Wis. RACIBORSKIA Woloszyhska 1919, p. 199 Cells attached, inversely triangular-ellipsoid as seen from the front, ellipsoid when seen in vertical view, the poles tipped with a single stout spine; attached by a short stalk to the substrate; in side view the upper margin straight, the 2 lateral margins straight or slightly convex, converging to the thick stalk; reproduction (?). [ 489 ] Raciborskia bicornis Woloszynska 1919, p. 199 PI. 93, Figs. 4-7 Characteristics as described for the genus; cells 25-35y long, including the spines, 9-12” in diameter. Rare; attached to the aquatic moss Drepanocladus in 35 feet of water; on large filamentous algae. Wis. TETRADINIUM Klebs 1912, p. 408 Cells triangular or tetrahedral, attached by a short stalk to a substrate, the angles tipped with 1 or 2 short, stout spines; chromato- phores many small ovate discs; nucleus central; reproduction by the formation of 2 swarmers in each cell. Key to the Species Angles’ of the’ cells tipped’ with 2 spines 2 T. javanicum Aneles of the/cellsitipped with spine 2 2 T. simplex Tetradinium javanicum Klebs 1912, p. 408 PI. 93, Fig. 3 Cells inversely pyramidate when seen from the front, the dorsal margin straight or slightly convex, the lateral margins convex, con- verging to a short, stout stalk which attaches the cell to the substrate; angles of the cell furnished with 2 short curved spines: cells 35-50p in diameter. Attached to filamentous algae. Mich., Wis. Tetradinium simplex Prescott in Prescott, Silva, & Wade 1949, p. 89 Pl: 107, Fig. 2 Cells inversely triangular, sessile, with scarcely any stipe, on fila- mentous algae, the dorsal margin broadly convex in front view, the angles tipped with a single, downward projecting spine; triangular in top view, the angles bearing a short spine; cells 12-25 in diam- eter, 12-20, high. On filamentous algae in shallow water of acid ponds. Mich. CLASS CRYPTOPHYCEAE In this group the organisms are mostly motile by means of 2 apical or lateral flagella (Cryptomonadales), but coccoid forms (Cryto- coccales) have been placed here also. The cells are dorsiventrally flattened, ovoid, slipper-shaped, or reniform, and possess a longitudi- nal furrow. In some, a gullet extends inwardly from the furrow in the anterior end of the cell. The pigments are dark golden-brown, [ 440 ] localized in (usually) 2 parietal and (in our specimens ) laminate chromatophores which may possess pyrenoids. Both starch ( staining blue with iodine) and oil are produced as food reserves. The cells are uninucleate and possess a contractile vacuole. In some forms trichocysts border the furrow. There are 3 subgroups, one of which is without pigmentation. Key to the Genera Glee Pasen bi 3.5 ooo. sinin odin uct Se ee Bint Pn Chroomonas ( Cryptochrysideae ) Culllet Soresent ..22..6..5. 00. ee ee eee Ea crt ds xaces.. CRY PEOMONGS ( Cryptomonadeae ) CHROOMONAS Hansgirg 1885, p. 230 Cells swimming by 2 apical flagella, dorsiventrally flattened, elongate-ellipsoid or pyriform, broader toward the anterior end, which is unsymmetrically bilobed, narrowed but broadly rounded at the posterior end; longitudinal furrow narrow and shallow, with- out a gullet, extending farther on the ventral surface than on the dorsal; chromatophores 2 lateral parietal bands. Chroomonas Nordstedtii Hansgirg 1885, p: 230 Pl. 95, Fig. 45 Cells slipper-shaped, broader toward the anterior end, which is unsymmetrically bilobed; narrowed posteriorly but broadly rounded at the pole; chromatophores 2 broad, parietal bands; cells 9-16, long, 4-8, in diameter. Common in shallow water of lakes and among algae masses and decaying vegetation; in shallow pools and bogs. Wis. CRYPTOMONAS Ehrenberg 1838, p. 40 Cells slipper-shaped, dorsiventrally flattened, convex on the dorsal surface, flat or concave ventrally, with a broad and con- spicuous longitudinal furrow from which a gullet extends inwardly from the anterior end; flagella 2, attached on the ventral surface at the anterior end; chromatophores | or 2, lateral and parietal; starch grains often present in the form of short rods; trichocysts sometimes discernible along the margins of the furrow; contractile vacuoles 1-3. Key to the Species Gullet extending scarcely to the middle of thevcell; cells: 15-3 2inlongeemern ee ur ee OY C. erosa Gullet longer, extending nearly *4 the length of thescell-cellsilarsersupitorcosm louesiens 2a Se C. ovata [ 441 ] ~ Cryptomonas erosa Ehrenberg 1838, p. 41 Pl. 95, Fig. 39 Cells broadly ovate or ellipsoid, with the left hand margin (as seen from the ventral side) arcuate and more convex than the right; apex almost evenly bilobed, the apical depression deep, the. gullet broad, extending about 1% or less the length of the cell; chromato- phores 2 parietal elongate plates, brown (in our specimens), blue- green or reddish; cells 8-16, in diameter, 15-32, long. In stagnant waters; swamps; tychoplanktonic in small lakes. Mich., Wis. Cryptomonas ovata Ehrenberg 1838, p. 41 Pl. 95, Fig. 40 Cells broadly ellipsoid or ovate, the left hand margin (as seen from the ventral side) symmetrically convex, the right nearly straight; apex unsymmetrically bilobed, the apical depression broad and shallow, gullet extending about 34 the length of the cell; chromato- phores 2 elongate parietal plates, brown; cells 5-18 in diameter, 20-80p long. Euplankter; in lakes and ponds. Mich., Wis. [ 442 | DIVISION CYANOPHYTA In this division the cells are without chromoplastids, the pigments being diffused generally throughout the peripheral portion of the protoplast. In some forms the pigments occur as granules crowded and somewhat localized just within the cell membrane. Besides the usual complement of pigments found in the green algae (although chlorophyll-b is lacking in the Cyanophyta), phycocyanin (water- soluble) and myxophycean phycoerythrin may be present. Different concentration and combinations of these pigments are responsible for the multitudinous colors exhibited by the blue-green algae. Photosynthetic products are glycogen and glycoproteins rather than starch. Frequently proteinaceous granules (cyanophycin) are present. There is no definite nucleus, although the presence of chromatin bodies has been proved in the central region of the cell. Usually the cells or colonies of individuals are invested by muci- laginous substances, which may be either soft and watery or firm enough to form a definite sheath. The cell membrane is thin and is composed of two layers, the outer one gelatinous and contributing to the investing mucilage. Many forms contain pseudovacuoles which are dark and refractive and sometimes cause the cells to appear black, reddish, or purple. According to some investigators, these are gas vacuoles; others identify them as pockets of mucilage. Reproduction occurs principally by fission and by fragmentation, but in some of the filamentous members, akinetes, sometimes referred to as gonidia, function as reproductive cells. Sexual reproduction is unknown in the Cyanophyta. In a few forms, endospores may be employed. These are especially characteristic of the Chamaesipho- nales where gonidia-like bodies are formed from the protoplast by either simultaneous or successive constrictions or divisions. Colonial organization is very simple, and the range of architecture is limited, the branched trichome being the climax of structural complexity. As interpreted here, the Cyanophyta include 2 classes, the blue- green algae or Myxophyceae, and the Chlorobacteriaceae, a group of pigmented, bacteria-like organisms. CLASS MYXOPHYCEAE The Chamaesiphonales and Chroococcales constitute the tribe Coccogoneae, and the Hormogonales the tribe Hormogoneae of some authors. [ 443 ] Doe Key to the Orders . Cells club-shaped unicells (in our specimens) showing basal- distal differentiation; solitary, or forming rather definite layers on rocks and shells, or epiphytic; reproduction by jnon-motiles endospores=. 2-2 sateis ce ele en CHAMAESIPHONALES . Cells other shapes; not reproducing by endospores_._-_-_= 2 . Cells coccoid; solitary or united in colonies of definite or indefinite shape; reproduction by fission CHROOCOCCALES . Plants filamentous; reproduction by fission, by hormogonial fragmentation; or bysdonidiae = tit ee ee HORMOGONALES ORDER CHROOCOCCALES This group includes plants which are unicellular or which form simple colonies of cells. The colonies may be definite or indefinite in shape, but there is no differentiation of cells, or interdependence. A copious gelatinous investment is present in most forms. See Daily (1942) and Drouet and Daily (1939) for critical studies of this group. FAMILY CHROOCOCCACEAE Unicellular or colonial, free-floating or attached to submerged or aerial substrates. There are no pseudofilamentous arrangements or expanses produced as in the Entophysalidaceae, another family in this order, which is not represented in our region. Key to the Genera . Plants unicellular or forming small aggregates of 2-8 \(rarelyy pr to o2)) Cells 2) ees ee ee ee 2 . Plants composed of many cells embedded in copious mucilage, with'or without apparent: cell) sheaths: ' =. aS eee eee 8 . Cells spherical, forming small clusters of 2-4 16=32"individuals® 22 Ses Ves ee Chroococcus (in part) » Cellsslonger than stheir. diameter sie. set ies) altar ee ee et 8 . Cells occurring as blue-green chromoplast-like loovebies) sin Collodiass lnon? Gallb 4 . Cells not occurring as chromoplast-like bodies InCOlorless NOStiGe lls meee eke a eer gee ee es Rees ee 5 . Host cell adherent, bearing long bristle-like setae; usually 2-4 host cells inclosed in a common mucilage Gloeochaete . Host cell free-floating, not bearing setae, not. inelosed in colonial mucilage-1:— = sss Glaucocystis . Cells with a gelatinous sheath; several individuals inclosed by a common mucilage —.._.--.-_--------------- Chroococcus (in part) . Cells solitary or clustered in small groups, without a miucilaginous investment...) "2 a ee 6 6Cf. the symbiotic genera Glaucocystis and Gloeochaete, in which the host cells may be grouped in small families. [ 444 ] , Gells\ pear-shaped, radiately ‘arranged == Marssoniella 6. Cells some other shape, not radiately arranged —________________ io 7. Cells cylindrical and strongly curved through 7% of a circle, often lying parallel and compact within the mucilage of other algae; minute, O:o—l. in’ diameters = Cyanarcus 7. Cells ovate or oblong; larger, up to 15 in diameter__________ Synechococcus 8. Cells 10 or more times their diameter in length; cylindrical, WGUSTCUNOH MATL, TREpOUU COHEN, (OVC TUB VUCO AON 9 82 Cells sound: ovate; or/Short-cy lind ric enna ee 1C 9. Cells narrowly fusiform, with tapering aicl | POUL. APICES 2)... 5vs aes eee eee ee Dactylococcopsis 9. Cells reniform or vermiform, rounded at the apices_____________ Rhabdoderma 10. Cells oblong or short-cylindric, with rounded ends, many 10. lige doe 12. 12. 13. 13. 14. 14. 15. 15. 16. 16. Wi L7- individuals irregularly and densely crowded in copious mucilage; individual cell sheaths evident or not Anacystis (in part) Including: a. Aphanothece (see p. 465) with individual cell sheaths not evident b. Gloeothece with individual cell sheaths distinct Cells spherical or ovate, sometimes ellipsoid, not cylindrical. 1] Cells round, embedded in copious mucilage, and forming shapeless masses on submerged or more frequently aerial ‘substrates Gloeocapsa Cells of other shapes, or if round not forming Shapeless masses (00 «subspates ee 42 Cells round or ovate, dividing in 2 directions fo, £ORm. Fectan Gul argyp late spteere oe eee 13 Cells dividing in 3 planes to form spherical, ovate, Or Shapelessvealoumall masses ee 14 Cells regularly arranged in rectilinear series. Merismopedia Cells irregularly arranged to form Somewhat rectangulamsplates ee. 2 Holopedium Colony hollow, the cells arranged toward the periphery 15 Colony not hollow; cells distributed throughout the colonial smucilage: nn eS 16 Cells at the ends of branching gelatinous strands which radiate from the center of the colony oe 12 Serle) nes a Gomphosphaeria Colonies without radiating gelatinous strands______________. Coelosphaerium Cells longer than wide, distributed throughout the colonial muci- lage, with or without evident individual cell sheaths _____ Anacystis (in part) Including: a. Aphanothece (see p. 465) without evident cell sheaths b. Gloeothece with individual cell sheaths evident Gels» ‘globose 2s eS 17 Cells evenly and remotely distributed within the colonial mucilage; pseudovacuoles wanting —_____--------------------------- Aphanocapsa Cells crowded, usually very densely so, not evenly distributed throughout the colonial mucilage; pseudovacuoles usually present ____----------------------------------- Microcystis CHROOCOCCUS Naegeli 1849, p. 45 One-celled, or an association of 2-32 spherical, hemispherical or ovate individuals, either free-floating, adhering to submerged sub- strates, or forming expansions in moist aerial habitats; each cell with a sheath which may be distinct from or (as in most planktonic species) confluent with the common mucilage investing a group of cells; several generations of sheaths present as a result of successive cell divisions; sheaths either hyaline or ochraceous; cell contents homogeneous or granular, not vacuolate, light to bright blue-green, olive-green, or yellowish. The sedentary species, especially, should be compared with Gloeocapsa, a genus which in some conditions and stages of develop- ment might be confused easily with Chroococcus. Gloeocapsa forms attached, gelatinous masses on either submerged substrates or, more commonly, in aerial habitats. In Gloeocapsa, many more cells are associated in families and clusters of families than in Chroococcus; the individual cell sheaths are usually thick and conspicuous, and the gelatinous matrix in which the cells are embedded is formed of several concentric layers. A small, isolated, and little-developed clump of Gloeocapsa resembles certain species of Chroococcus. It is desirable, therefore, to see a number of plants in a collection before attempting determinations. Key to the Species 1. Cells large, 13-70 in diameter__—_-----—---_-----__--------------— 9) iei@ellstsmaller, 1-5—10p in diameter Se 3 2. Maximum diameter of cell, including sheath, 504. C. turgidu 2. Cells larger, diameter 67—70y including the sheath ____ C. giganteus 3. Colonial mucilage or individual cell sheaths lamellate = ae 4 3. Colonial mucilage or individual cell sheaths not lamellate2 44 eee ber 5 4. Cells arranged in cubical (sarciniform) packets. C. Prescottii 4, Cells not in cubical packets _______—__________- C. varius 5. Cells arranged in cubical packets of from 4-8, or in multiple packets of 32 cells in Sarcina-like families ____________. C. Prescottii 5. Cells not arranged in cubical packets 6 6. Colonies free-floating in the euplankton —____---______________-------- 7 6. Colonies adhering to substrates, or entangled among other algae in tychoplankton —__-__-------------—---=-— 9 7. Colony of many cells within a homogeneous sheath, cells: 2=2 iin: Giamete ts ie ee ee C. minimus 7. Colony of 24 or fewer cells in a homogeneous sheath, cells usually more than 3 in diameter 8 8. Cells 8-4.5u in diameter, arranged at some distance from one another. ........-----------—--—------------ C. dispersus 8. Cells 6-12—(22), in diameter, arranged close together C. limneticus [ 446 ] 9. Cells (5)-G—8—(11)u in diameter; contents pale yellow. C. pallidus 9. Cells mostly smaller than above; contents blue-green —______________ 10 10. Cells oblong; 5-7—(10) in diameter; in groups of 2 inclosed in a homogeneous sheath_.._________________-__. C. minutus 10. Cells angular or irregularly globose, 3-44 in diameter; solitary or 2 together within homogeneous sheaths, sometimes forming small masses on submerged aquatic plants. —_------_-_- C. minor Chroococcus dispersus (Keissl.) Lemmermann 1904, p. 102 PI. 100, Fie. 7 A free-floating, flattened, ovate or irregularly-shaped colony of 4-16 spherical cells which are either single or arranged in small clusters, evenly distributed at some distance from one another in the mucilaginous envelope; individual cell sheaths not evident; cell contents bright blue-green (sometimes gray-green or pale blue- green); cells 3-4.5, in diameter. This species should be compared with C. limneticus, in which the colonies are globular and the cells are larger. Euplankter. Found in many lakes of both hard and soft water. Mich., Wis. Chroococcus dispersus var. minor G. M. Smith 1920, p. 28 Pl. 100, Figs. 1-3 A variety differing from the typical in having smaller cells, 1.7- 2.5 in diameter. Rare, but has been found in several lakes. Mich., Wis. Chroococcus giganteus W. West 1892, p. 741 Pl. 100, Fig. 16 Cells hemispherical or ovate, solitary or in groups of 2-5, inclosed by a wide, hyaline, lamellate envelope of mucilage in which indi- vidual cell sheaths are evident; cell contents bright blue-green and densely granular; cells, without sheath, 54-58, in diameter, 67—70n including the sheath. This species is, by far, the largest of the genus in our region. Except for its greater size it is not unlike C. turgidus with which it should be compared. Specimens of C. giganteus collected in Vilas County, Wisconsin, are so much like a large form of C. turgidus that I am inclined to regard the former as a variety maximum of the latter. Tychoplankter. Rare; in mixtures of other algae in shallow water. Mich., Wis. [ 447 ] Chroococcus limneticus Lemmermann 1898d, p. 153 Pl. 100, Figs. 4, 5 A free-floating, spherical or ovate colony of 4-32 spherical cells rather closely and evenly arranged, sometimes in groups of 2-4 cells as a result of rapid cell division; individual cell sheath usually indistinct and confluent with the hyaline, mucilaginous colonial envelope; cell contents dull to bright blue-green, not conspicuously granular; cells 6-12-22 in diameter, without sheath. This is one of the most common of all planktonic species found in our region. Its distribution in acid or soft water habitats suggests a specificity similar to that of C. turgidus in the tychoplankton of highly acid mediums. Euplankter. Found in many lakes, especially soft or semi-soft water. Mich., Wis. Chroococcus limneticus var. carneus (Chod. ) Lemmermann 1904, p. 101 Pl. 100, Fig. 6 A variety differing from the typical by its smaller size and the irregularity of cell distribution within the colonial envelope; cells 4-16 in number, 7-9, in diameter without sheath. Euplankter. Found in several lakes. Mich., Wis. Chroococcus limneticus var. distans G. M. Smith 1916, p. 481 Pl. 100, Fig. 8 A free-floating ovoid colony of 8-32 globose or hemispherical cells, rather widely separated (or in widely separated groups of individuals) within a hyaline; homogeneous, gelatinous colonial envelope; cell sheaths confluent with the colonial mucilage; cell con- tents homogeneous, gray to light blue-green; cells 6-8 in diameter. Euplankter. Found in several soft water lakes. Mich., Wis. Chroococcus limneticus var. elegans G. M. Smith 1916, p. 619 Pl. 100; Fig; 11 A free-floating colony of ovoid cells which are circular in one view but flattened when seen from the side; cells irregularly scattered in a wide, gelatinous colonial envelope; cell contents bright blue-green and non-granular; cells 18-22, in diameter without sheaths, 20-26 in diameter including the sheath. Euplankter. Mich., Wis. [ 448 ] Chroococcus limneticus var. subsalsus Lemmermann 1901c, p. 84 Pl. 100, Fig. 10 A globose or ovoid to ellipsoid colony of 8-32 spherical cells, evenly scattered within a wide, hyaline, and homogeneous colonial envelope of mucilage; individual cell sheaths not evident; cell con- tents bright blue-green and non-granular; cells smaller than in the typical plant, 3—4.5p in diameter without sheaths. Euplankter. Found in a number of lakes; rare but widely distrib- uted in our region. Mich., Wis. Chroococcus minimus ( Keissl.) Lemmermann 1904, p. 102 A globose or elliptical colony of 4-8 spherical or ovoid cells in a wide, hyaline, non-lamellated colonial envelope; cells 2-3» in diam- eter without sheaths; contents blue-green, non-granular. Euplankter. Wis. Chroococcus minor (Kuetz.) Naegeli 1849, p. 47 Pl. 100, Fig. 12 A small gelatinous attached and amorphous mass in which cells (spherical or angular from mutual compression) are irregularly scattered, singly, in pairs, or in larger groups resulting from repeated cell division; individual cell sheaths scarcely visible, confluent with the colonial envelope; cell contents pale to bright blue-green, non- granular; cells 3-4 in diameter without sheath. Growing on moist substrates or intermingled with dense clots of miscellaneous algae; often forming small masses on Potamogeton spp. or other submerged aquatics; sometimes buried in the decaying tissues of higher plants. Wis. Chroococcus minutus (Kuetz.) Naegeli 1849, p. 46 Pl. 100, Fig. 9 A small, amorphous, mucilaginous mass in which spherical or hemispherical cells are compactly arranged within a wide hyaline envelope; individual cell sheaths indistinct, not lamellated; cell contents blue-green, either homogeneous or finely granular; cells 5-7-(10)» in diameter without sheaths. Common in a great variety of both hard and soft water lakes; tychoplankter; found among dense growths of algae and higher aquatics in shallow water of lakes, cut-offs from lakes, and in swamps; sometimes appearing incidentally in tow samples from Sphagnum bogs. Mich., Wis. [ 449 ] Chroococcus pallidus Naegeli 1849, p. 46 Pl. 100, Fig. 14 Single-celled or, more frequently, a small colony of 2-4-(8) spherical individuals inclosed by an oval or globose, wide, hyaline or yellowish, homogeneous envelope of mucilage; individual cell sheaths indistinct; contents pale blue-green; cells (5)-6-11p in diameter without sheath. Plants of this species are to be found on moist aerial substrates or scattered among algae in shallow water tychoplankton. Mich., Wis. Chroococcus Prescottii Drouet & Daily in Drouet 1942, p. 127 P1.100, Fig. 13 A free-floating colony of 4-16-32 spherical cells arranged in 2 planes to form cubes or sarciniform clusters, inclosed in a rectan- gularly shaped, hyaline, colonial envelope which is often lamellated, with individual cells or quartets of cells inclosed by a sheath; cell contents bright blue-green; finely granular, cells 5-8» in diameter; colony (of 16 cells) 18-224 wide, 30-42 long, and about as thick as wide. This plant was questionably listed as Eucapsis alpina Clements and Schantz by Prescott and Croasdale (1937). It should be com- pared with that species, the cells of which are similarly arranged but more numerous in the colony and in which the colonial sheath is without lamellations. Not uncommon in the tychoplankton of acid habitats, intermin- gled with dense growths of other algae, especially desmids, and commonly associated with C. turgidus. Mich., Wis. Chroococcus turgidus (Kuetz.) Naegeli 1849, p. 46 Pl. 100, Fig. 19 A free-floating colony of 2-4 ovoid or hemispherical cells inclosed by a very wide (usually), hyaline, and lamellate colonial sheath; cells bright blue-green, contents sometimes coarsely granular, in- closed by individual sheaths, 8-324 in diameter without sheath, 15-50, wide including sheath. Tychoplankter. Common in many lakes and in bogs. This is a relatively large species, attaining maximum size and abundance in Sphagnum bogs. Mich., Wis. [ 450 J Chroococcus varius A. Braun in Rabenhorst 1861-1878, Nos. 246, 248, 252 Pl. 100, Fig. 15 An irregularly shaped colony of 2-8 spherical cells inclosed by a hyaline, sometimes colored, gelatinous envelope, forming dark-green or brownish masses on moist aerial substrates, or among other algae in shallow water; colonial envelope lightly lamellate, individual cell sheaths not distinctly evident; cell contents blue-green or olive, not granular; cells 2-4 in diameter. Most of the records of this species in North America are from moist substrates near geysers and hot springs, or from sulphur water. Not infrequent in the tychoplankton of a variety of both hard and soft water lakes. Wis. GLOEOCAPSA Kuetzing 1843, p. 174 Essentially unicellular but with many individuals aggregated to form amorphous gelatinous masses of spherical cells, or as associa- tions of families of irregularly arranged cells, each individual in- closed by a lamellate, mucilaginous, and usually thick sheath; plant mass blue-green, reddish; yellowish, or brown; cell contents blue- green or yellowish to olive-green, homogeneous or (more often) granular, without pseudovacuoles. This genus should be compared with those attached or sedentary species of Chroococcus in which the colonial envelopes of the families are persistent and do not become confluent with the general investing mucilage. In general, Gloeocapsa masses contain many more cells than Chroococcus, and the lamellate, thicker sheaths are more conspicuous, whereas in some (especially planktonic) species of the latter genus they tend to become confluent. Key to the Species 1. Sheaths yellowish or brownish to orange_______-_----------------------- G. rupestris ee Sheathiscaeo lor es sess sein te he week eer eC Dee el 9 2. Cells 6—9u in diameter without sheaths, 11—-12u ATUL ATIVE CE TERWVA EELS res this fae aeeaeeae ea cn ene ere G. calcarea Cals: Srrvaill eer eee eo ee ae ioe aL 8 . Plants encrusting on moist substrates; cells 2-4y in diameter __ G. aeruginosa . Plants free-floating (tychoplankton ); cells 0:7=2:8a: in- diameter 2 a ee G. punctata woh Gloeocapsa aeruginosa (Carm.) Kuetzing 1845-1849, Tab. Phyc., Pl. 21, Fig. 2 Pl. 101, Fig. 6 Plant mass with firm or leathery mucilage, blue-green; cells spherical, with blue-green, homogeneous contents, arranged in small [ 451 ] families and inclosed by wide, colorless sheaths which are only slightly lamellate; cells 2-4 in diameter, with sheaths 4-8 wide. On shore and in tychoplankton of shallow lake. Mich., Wis. Gloeocapsa calcarea Tilden 1898, p. 29 Plant mass light gray-green to blue-green, forming a calcareous crust on moist substrates; cells spherical, in families of 4-16 indi- viduals inclosed in thin, colorless sheaths, 6-9, in diameter, with sheaths 11-12 wide. On wet boards, Osceola, Wisconsin. Gloeocapsa punctata Naegeli 1849, p. 51 Pl. 101, Fig. 7 Plant mass blue-green, floating or entangled among other algae, consisting of small aggregates of 4-16 individuals which are spher- ical and inclosed by thick sheaths that are weakly lamellate out- wardly but which break down and become confluent with the colonial mucilage internally; cells 0.75-2.31 in diameter; contents blue-green, homogeneous. This species may be identical with G. aurata Stiz., a species described as having yellowish envelopes that are not lamellate. Sheath color and presence or absence of lamellatigns seem to be such variable characters that alone they are inadequate for the separation of species. On soil and in tychoplankton of soft water lakes. Wis. Gloeocapsa rupestris Kuetzing 1845-1849, Tab. Phyc., 1, p. 17 Pl. 107, Fig. 13 Plant mass dark-colored, brownish, encrusting; cells blue-green, spherical, in few-celled colonies; cell sheaths thick and but slightly lamellated, yellowish or orange-brown; cells 6-9. in diameter; families 15-75, in diameter. Mich. APHANOCAPSA Naegeli 1849, p. 52 A globular, ovate, or sometimes amorphous mass, gelatinous, and free-floating, in which spherical cells are usually widely and evenly distributed through a yellowish or hyaline, homogeneous colonial mucilage; individual cell sheaths not evident; cells often in pairs as a result of recent division; contents homogeneous or finely gran- ular, pale gray-green to bright blue-green. See description of Micro- cystis, page 455. [ 452 ] These plants are common in plankton and frequently appear with Microcystis aeruginosa in water blooms, but they never become dominant components of such blooms in our region. Most species show a preference for soft water and acid habitats. Key to the Species 1. Cell endophytic in the mucilage of other algae____-_»»_=_ A. endophytica deg @elishiree=biviri tf... a2 ee ee eee se A a te 2 2. Cells 5-6u in diameter, colony usually free-floating, Sometimess attached —-..-2 5 sx 2u 5 00 Bae eRe A. rivularis Orn@ellsismiallereek 2:1 > eee Dee ernie dio ete hd 8 3. Cells bright blue-green; rather crowded ___.-_____-__________ A. Grevillei 3. Cells gray-green or bluish-green, colonial mass not deeply colored; cells not crowded (except var. conferta of A. elachista) -_-__________- 4 Al. (Calls Gs 2Mbyn, aio, Glieionetnere A. pulchra 4\. (Calls less Gein, Syn tin Ghtimneter 5 5. Cells minute, coccoid, lu in diameter or less = A. delicatissima i, Calls Tg olen ty Gliese A. elachista Aphanocapsa delicatissima West & West 1912, p. 431 Pl. 101, Figs. 8, 9 Colonies spherical or elliptical, free-floating; cells minute, bluish, evenly distributed throughout copious, colorless mucilage, 0.5-0.8p in diameter. Common in the tychoplankton of many lakes. Most frequent in soft or acid water. Mich., Wis. Aphanocapsa elachista West & West 1895b, p. 276 Colonies spherical or ellipsoid, free-floating or intermingled with other algae, small and few-celled, the colonial mass pale blue-green; cells small, globose, often in pairs and widely separated in colorless mucilage, 1.5-2.5, in diameter. Mich., Wis. Aphanocapsa elachista var. conferta West & West 1912, p. 432 PL JO Bigs. 10,07 Colonies ovate or globose, frequently irregular in shape (in our specimens commonly very large) up to 150» in diameter; cells spherical, crowded within a hyaline colonial mucilage, often with many cells in pairs, 1.6-2.0y in diameter. Euplankter. Rare to common in several soft water lakes. Mich., Wis. [ 453 ] Aphanocapsa elachista var. planctonica G. M. Smith 1920, p. 42 Pl. 101, Fig. 12 Cells less crowded than in var. conferta, evenly dispersed through- out a colorless, colonial mucilage, 2-3» in diameter. Euplankter. Rare in several, mostly soft water, lakes. Mich., Wis. Aphanocapsa endophytica G. M. Smith 1920, p. 42 Pl. 101, Fig. 18 Endophytic in the colonial mucilage of Microcystis; cells solitary or arranged in small clumps which are evenly dispersed and remote from one another; cell contents homogeneous, pale to bright blue- green; cell 2u in diameter. Reported as common in Poor Farm Lake, Wisconsin. Aphanocapsa Grevillei (Hass. ) Rabenhorst 1865, p. 50 Pl10U Figs. lo, 16 Free-floating colonies, sometimes on moist soil, spherical or, in age, irregularly shaped; cells in pairs, in groups of four and crowded, or solitary, evenly dispersed through colorless mucilage, blue-green, with pseudovacuoles, 3.8-5.5u in diameter. Rare; in the tychoplankton of several lakes. Mich., Wis. Aphanocapsa pulchra (Kuetz.) Rabenhorst 1865, p. 49 Pl. 101, Fig. 14 Colonies ovate or globose, free-floating; cells spherical, loosely and evenly dispersed within a copious mucilage, contents blue- green, finely granular, 3.4-4.5u in diameter. This is the most common species of the genus in our collections of phytoplankters. It is often a component of water blooms in hard water lakes although not infrequently found intermingled and attached among other algae in shallow water of Sphagnum bogs. The colonies often attain macroscopic size. Mich., Wis. Aphanocapsa rivularis (Carm.) Rabenhorst 1865, p. 49 Pl 101. Pigs 17 A free-floating or sessile, amorphous, or tubular to spherical colony of globose cells which have bright blue-green, granular contents; cells solitary or in pairs and scattered at some distance from one another within the colonial mucilage; cells 5-6 in diameter. The slightly larger size of the cells, and the more scattered ar- rangement separate this species from A. Grevillei. Euplankter. Mich., Wis. [ 454 ] MICROCYSTIS Kuetzing 1833a, p. 372" A free-floating or sedentary colony of numerous spherical cells closely and irregularly arranged within copious mucilage, forming ovate, globose, or irregularly shaped masses which are often lacerate or perforate; individual cell sheaths confluent with the colonial mucilage; cell contents pale or bright blue-green, or appearing black or purplish because of pseudovacuoles, present in most species, which are large and conspicuous, or sometimes numerous and small. This genus should be compared with Aphanocapsa in which the spherical cells are evenly and widely spaced within a definitely shaped (usually spherical ) colonial investment of mucilage. Unlike most of the species of Microcystis, the cells of Aphanocapsa are always without pseudovacuoles. The reader is referred to Elenkin (1924), to Drouet and Daily (1939), and to Teiling (1946), for critical remarks on the synonymy of species in this genus. In the following key those species which have been reassigned by students of the genus are given in paren- theses. Key to the Species 1. Colonies saccate, lobed and clathrate, the colonial mucilage thick and! refractiveum young, plats .- 2 =) M. aeruginosa 1. Colonies globular, or ovate, definite in shape, notepertorate’ OL CLAuanated ee ee SE ee 2 2. Cells without pseudovacuoles or, if present, simall Rand MnCOris pico tis eee nee ae ee es ee 4 2. Cells with large and conspicuous pseudovacuoles 3) 3. Colonies simple, a large mass of much crowded cells inclosed by a transparent, mucilaginous envelope PS coal (M. flos-aquae ) M. aeruginosa 3. Colonies compound, several groups of cells, each with a colonial envelope, inclosed within a common mucilage (M. ichthyoblabe ) M. aeruginosa 4. Cells 1-2u in diameter, small and numerous but uniformly distributed within the enlonial AUC ASE 4s 30) hat een SEs M. incerta 4. Cells 2-3u in diameter, compactly arranged within, the colonial mucilage ose eee eS (M. pulverea) M. incerta 7See notes by Drouet and Daily (Daily, 1942, p. 638) in which they explain the use of the generic name Polycystis Kuetz. for the species grouped under Microcystis Kuetz. I prefer to retain the latter name because it is generally accepted and well understood. Although Microcystis was used originally for a miscellany of organisms, and at one time only for flagellates, those species to which it referred in earlier times have all been transferred to their proper places in other genera. Since the name Microcystis no longer applies to any of them, there is no danger of taxonomic confusion. In any case, the creation of Polycystis as a genus by Kuetzing in 1849 was antedated by the use of that name for a genus of Uredineae (Polycystis Leveille 1846, Annales Sci. Nat. Bot., 5 (Ser. 3), p. 269). This precludes the revival of the name for the species now grouped under Microcystis. [ 455 ] Microcystis aeruginosa Kuetz.; emend. Elenkin 1924, p. 14 [M. aeruginosa var. major G. M. Smith; M. flos-aquae (Wittr.) Kirchner; M. ichthyoblabe Kuetzing] Pl. 102, Figs. 1-4 An ovate, spherical, or irregularly lobed, saccate and clathrate colony of numerous spherical cells which are much crowded within a gelatinous matrix (several colonies sometimes invested by a com- mon tegument); colonial mucilage hyaline and homogeneous, re- taining a definite shape; cell contents blue-green, highly granular and with conspicuous pseudovacuoles; cells 3-4.5u in diameter. Very common in hard water lakes, becoming especially abundant during late summer periods and appearing in such dense growths in favorable habitats as to color the water. Mich., Wis. This species is a frequent component of water blooms, especially in lakes with eutrophic characteristics, although it is common to a great variety of aquatic habitats. The tendency to float high in the water results in the formation of large, macroscopic clots and floating crusts which develop as the plants push each other above the surface. Like Aphanizomenon flos-aquae, this species is notorious as a spoiler of water for domestic uses, swimming, and recreation and often causes the death of fish in heavily infested lakes. In assigning species of Microcystis collected in this region, I have followed the nomenclature recommended by students who have given special attention to the genus. There long have been recog- nized two species names for the very common planktonic forms of Microcystis, which show considerable variation in colony form. The name M. aeruginosa Kuetz. has been used for the plant which has a perforated or clathrate and much lobed colony. The name M. flos-aquae (Wittr.) Kirch. has been applied to the form with globose, non-perforate or non-clathrate colonies. Elenkin (1924, p: 14), after a critical study, reduced this latter species to synonymy with M. aeruginosa Kuetz. At the same time he recognized two forms: fa. minor Elenkin, cells 3-54 in diameter, and fa. major ( Wittr.) Elenkin, cells 4-7, in diameter. It is held by some that the perforate condition of the colony is merely a character accompany- ing age and that the many intergrading variations are related to physical conditions in the habitat such as water currents, or to methods of collecting. Virieux (1916) and others (Drouet and Daily, 1939) also have advocated uniting M. aeruginosa and M. flos-aquae. Drouet and Daily (I.c.) have published on the synonymy of Microcystis aeruginosa and have discussed the fresh-water species [ 456 ] of the genus critically. Teiling (1946) advocates the retention of the two names. If the interpretations of Elenkin (J.c.), Drouet and Daily (l.c.) and others are followed, the name M. flos-aquae (Wittr.) Kirch. will be discarded. The view which holds that the clathrate condition is a result of age only, is not compatible with the many observations which I have made on collections of these forms in which very large, globose, solid colonies dominate the habitat, forming almost pure growths in some lakes. Such colonies mature and disintegrate without assuming the perforate and clathrate condition which one might expect to develop if age were responsible for the aeruginosa form. Illustrations of some of the various expressions which this plankter assumes are illustrated on Plate 102, Figs. 1-4. See also Fjerdingstad (1945) on the retention of these two names. Microcystis incerta Lemmermann 1899a, p. 132 [M. pulverea (Wood) Migula] Pl. 102, Fig. 5 A spherical or lobed colony, consisting usually of many small, spherical, closely arranged cells, inclosed by a thin, mucilaginous envelope; cells 0.5-2» in diameter; cell contents gray-green to light blue-green; pseudovacuoles lacking or minute and inconspicuous; colonies either tychoplanktonic, or forming blue-green granular masses on the bottom. Not uncommon, occurring in both hard and soft water lakes. Mich., Wis. The small size and compact arrangement of the cells, and the minute pseudovacuoles are characteristics which aid in the identi- fication of this species. I follow Drouet and Daily (l.c.) in assigning forms ordinarily listed under the name of M. pulverea (Wood) Migula to M. incerta Lemm. The plant listed by other authors as Anacystis pulverea Wolle has been transferred to M. glauca (Wolle) by Drouet and Daily (I.c.). Apparently it has ‘not been collected in our region. It inhabits hard water lakes rich in lime and is to be expected in lakes of southern Michigan and Wisconsin. MERISMOPEDIA Meyen 1839, p. 67 A plate-like colony of ovate or globose cells compactly or loosely arranged in rows both transversely and longitudinally, inclosed by a hyaline, homogeneous, mucilage; colony quadrangular (becoming distorted in age) or with margins rolled and convolute; cell contents homogeneous (rarely with pseudovacuoles ); individual cell sheaths [ 457 ] indistinct in most species and confluent with the colonial mucilage. The plate-like form of the Merismopedia colony and the regularity of cell arrangement make identification of this genus certain. Only in rare instances are Chroococcus cells found in a somewhat plate- like colony, and the examination of a number of individuals will confirm the identification. Key to the Species 1. Colony a very broad, membranaceous plate with imarcins convolute-and :enrolleds el. sass ERE Aen ese M. convoluta 1. Colony: ‘a; flat plate 240 Gers bon er oe eee eee eee 2 2Gellsiwithretractivesvacuo lesi a. => 45 0e.0 32 522 ia ee ae 6 5. Cells 1-1.5u in diameter, about twice the diameter in length A. nidulans 5. Cells larger, (1)—1.8-2u in diameter, slender, up to Sitimes: the diameter inilength «12 Ae) es BE A. saxicola 6. Cells ovate to nearly spherical, not cylindric -___._________. A. gelatinosa 6. Cells cylindrical, up to 3 times the diameter in length .____________»______ a 7. Plant mass very pale, gray to light blue-green_______________ 8 ice Blantemassi brig latly Colored 2.5 ee teens a See eee ee 9 8. Cells 3.3-3.7—(4.5) in diameter, up to Tu long-sdensely ramamced. ies seaee ee title 52 ee A. microscopica 8. Cells larger, 4.5-5.6u in diameter, up to 8.54 long; loosely arranged... (A. pallida—see Gloeothece rupestris ) Anacystis rupestris 9. Cells elongate-cylindric, 2.4—-3u in diameter, up to 3 times the diameter in length; loosely arranged_.____________ A. microspora 9. Cells short-cylindric, 2-83.54 in diameter, up to 2 times the diameter in length; densely arranged_________________ (A. Castagnei ) Anacystis marginata [ 466 ] Aphanothece Castagnei (de Bréb.) Rabenhorst 1865, p. 76 [Anacystis marginata Meneghini 1837] Pl. 105, Figs. 5, 6 Cells ellipsoid or ovate to subcylindric, densely arranged within a gelatinous, amorphous mass which is olive-green or brownish; cells of various shapes and sizes within the same colony, oblong or poly- gonal when compressed; 2-3.5p in diameter, 4-8» long; cell contents finely granular and olive-green. In ditches; in tychoplankton of lakes. Wis. Aphanothece clathrata G. S. West in West & West 1906, p. 111 Pl. 104, Figs. 6, 7 Colonies free-floating, irregular in shape and usually clathrate with large perforations; cells cylindrical or elongate-elliptic, straight or slightly curved, scattered through a transparent mucilage; cells 0.8-1.2u in diameter, 3-6, long. The small size of this species and the clathrate colony are char- acters which separate this species from most of the other free-floating forms of Aphanothece. Its lack of pseudovacuoles differentiates it from A. pulverulenta Bachmann, another species with minute cells (ellipsoid in shape) which possess pseudovacuoles. Floating in several soft water lakes. Mich., Wis. Aphanothece gelatinosa (Henn.) Lemmermann 1910, p. 69 Pl. 104, Fig. 8 Cells ovate, nearly spherical, compactly arranged in globular, blue-green to brown gelatinous attached masses; cell contents blue- green; cells 3.8—4y in diameter, 44.5, long. This plant is differentiated by the color of the colonial mass and by the size of the cells from Aphanothece stagnina. It is possibly only a variation of that species, and the assigned name is used here tentatively to designate a form which does not agree with typical A. stagnina. I have not seen type specimens of A. gelatinosa for comparison. In a hard water swamp and in lakes with a high calcium carbonate content. Wis. Aphanothece microscopica Naegeli 1849, p. 59 Pl. 104, Figs. 9, 10 Cells ovate to subglobose, densely arranged in small, free-floating or attached ovate colonies; cell sheaths not evident; cell contents [ 467 ] light blue-green, finely granular; cells 3.3-3.7-(4.5) in diameter, 5.5-7.5p long. This plant has smaller cells than those described for Aphanothece prasina, and they are not cylindrical. Euplankter. Mich., Wis. Aphanothece microspora (Menegh. ) Rabenhorst 1863, p. 76 Pl. 105, Figs. 7-9 Cells short-cylindric with rounded ends, loosely arranged, solitary or in pairs in small, amorphous, olive or yellow-green gelatinous masses; cells 2.4-2.7 in diameter, 6-10, long. Fairly abundant in a few hard water lakes; entangled in tycho- plankton, among filamentous algae. Wis. Aphanothece nidulans P. Richter 1884, p. 128 Pl. 104, Figs. 2,3 Cells short-cylindric, broadly rounded at the apices, densely and evenly distributed in small ovate or spherical colonies, inclosed by a colorless mucilage in which individual cell sheaths are not distinct; cells small, 1-1.54 in diameter, 3-3.5y long; cell contents pale blue- reen. : This is a euplanktonic species, often forming a major portion of a rich flocculent algal population in shallow water, especially in hard water lakes. The minute bacilliform cells give colonies the appearance of a bacterioidal mass. Mich., Wis. Aphanothece nidulans var. endophytica West & West 1912, p. 482 Pl. 105, Fig. 16 Cells within the mucilage of other colonial Cyanophyta, such as Coelosphaerium and Microcystis, where they are evenly distributed throughout the envelope of the host; cells 0.8-1.54 in diameter, 2.54.5 long. Rare; in the euplankton of lakes of fairly soft water. Wis. Aphanothece saxicola Naegeli 1849, p. 60 Pl. 104, Fig. 1 Cells cylindrical with rounded ends, 2—3.5 times longer than wide, loosely arranged, solitary or in pairs within amorphous, homo- geneous, and almost colorless mucilage; colonies free-floating or attached; cell contents pale blue-green; cells (1)-1.5-1.8-(2)p in diameter, 2.8-6y long. The cells of this species are bacilliform and are almost colorless. [ 468 ] Because of their minute size they may easily be mistaken for a colony of bacteria. Their faint bluish-green pigmentation is scarcely to be differentiated from the apparently similar color of unstained bacteria caused by light refraction in microscopical examination. The name A. saxicola Naeg. is used tentatively for this small plant. It is nearest A. nidulans P. Richt. in size but is more slender and the cells are more loosely arranged in the colonial mucilage than described for A. nidulans. According to Drouet and Daily (l.c.) Aphanothece saxicola is synonymous with Anacystis marginata Men- eghini, the original description of which does not agree with our specimens. The former name is used here, therefore, to refer to a plant which agrees with the description of A. saxicola. In Sphagnum bogs; tychoplankter in lakes. Mich., Wis. Aphanothece stagnina (Spreng.) A. Braun in Rabenhorst 1864-1869, Algen No. 1572 [Anacystis rupestris (Lyngb.) Drouet & Daily in Daily 1942, p. 650] Pl. 103, Figs. 14-16 Cells short cylindric, evenly distributed throughout an ovate or irregularly globose gelatinous mass; colonies bright green, attached and attaining macroscopic size; cell contents usually bright blue- green (sometimes pale), homogeneous; cells sheaths diffuent and not evident; cells 3.7—7 in diameter, 5—8p long. Free-floating colonies with larger cells are usually referred to Aphanothece prasina A. Braun. In his treatment of the genus, Daily has assigned the name Anacystis rupestris var. prasina (A. Braun ) Drouet & Daily to this form and does not separate it from Aphano- thece stagnina (Spreng.) A. Braun. Common in many lakes; usually in shallow water; often forming almost continuous gelatinous expanses on the bottom of favorable eutrophic habitats. Mich., Wis. COELOSPHAERIUM Naegeli 1849, p. 54 A free-floating, globular, ovate, or irregularly shaped colony of spherical or subpyriform cells arranged in the colonial mucilage, in a single peripheral layer, producing a hollow sac; cell contents pale to bright blue-green, either homogeneous or with numerous refrac- tive pseudovacuoles; colonial envelope homogeneous, or with radiat- ing, gelatinous fibrils. This genus should be compared with Aphanocapsa, in which the cells are scattered throughout the colonial mucilage. [| 469 ] Key to the Species i (Cells: 5—Fupin; Gtameter, ‘spherical. 22) 5 ee C. dubium i. (Gellsesmaller. either sphericalior ovate 2 sss ee 2 ZuCellssround, wp tor4 wai diameters sss =e eee ea C. Kuetzingianum 2. Cellssovate tovellitysoic sea Stee eo Rae ei ee ee ed eden Ces 3 3. Cells appearing dark and granular because of pseudovacuoles; 2—suein CiaMeten, S;0-Ou) ONG = at cates eee ee C. Naegelianum 3. Cells pale blue-green, without pseudovacuoles, 1[2)5pein.diameter; 2—3:2)¢ long) = 0514 Ae ae C. pallidum Coelosphaerium dubium Grunow in Rabenhorst 1865, p. 55 Pl. 106, Fig. 1 Plant a spherical or sometimes irregularly-shaped colony of spher- ical cells, or an aggregate of colonies in a common gelatinous enve- lope; free-floating; cells densely arranged in the colonial mucilage to form a peripheral layer, thus producing a hollow sphere; cell contents blue-green, either homogeneous or with pseudovacuoles; cells 5-7y in diameter; compound colonies as much as 300y in diameter. Rare in euplankton. Wis. Coelosphaerium Kuetzingianum Naegeli 1849, p. 54 Pl. 106, Fig. 2 A free-floating spherical, or ovate, gelatinous colony of spherical or subspherical cells arranged at some distance from one another (usually) at the periphery of the colonial envelope; cell contents homogeneous (rarely with pseudovacuoles ), light blue-green; cells 2.5—4u in diameter. This species is not quite so common in our collections as C. Naegelianum. It is, however, widely distributed in a variety of lakes, mostly hard or semi-hard water habitats. It seems never to become conspicuous in water blooms as does C. Naegelianum. It is to be differentiated from that species by the shape of the cells and by their lack of the reddish-brown color produced by many pseudo- vacuoles. It also lacks the radiating gelatinous fibrils in the colonial mucilage possessed by C. Naegelianum. Mich., Wis. Coelosphaerium Naegelianum Unger 1854, p. 196 Pl. 106, Fig. 4 A free-floating, spherical, ovate, or lobed colony of ovate or ellipsoid cells arranged to form a dense peripheral layer in the [ 470 ] colonial mucilage; cell contents with many pseudovacuoles, giving a dark reddish-brown or black granular appearance to the cell and making the colony opaque when viewed microscopically; colonial mucilage with many radiating fibrillar concretions which clearly show when the colony disintegrates with age; cells 2-34 wide, 3.5-6 long. This species is very common and occurs in abundance in suitable habitats such as hard water, highly nitrogenous lakes with adequate carbon dioxide content. In late summer periods these plants are often conspicuous components of water blooms. Coelosphaerium Naegelianum Unger is associated with Microcystis aeruginosa Kuetzing emend. Elenkin, Lyngbya Birgei G. M. Smith, Coelo- sphaerium Kuetzingianum Naeg. and Gloeotrichia echinulata (J. E. Smith) P. Richter (see C. Kuetzingianum above). When the colony is disintegrating the cells and the fibrils have a distinct radiate appearance and the cells seem to be at the ends of fine strands from the center of the colony. The original description of this plant agrees with our specimens. In DeToni (1907, p. 100), the name is regarded as synonymous with C. Kuetzingianum Naeg. Coelosphaerium pallidum Lemmermann 1898d, p. 154 Pl. 106, Fig. 3 A spherical or ovate colony of small, ovate cells crowded, but evenly arranged, within the periphery of the colonial mucilage; cell contents pale blue-green, without pseudovacuoles; cells 1-2.5y in diameter, 2-3.2 long; colony 30-40, in diameter. This species has smaller and more crowded cells than others in our collections. These characters, together with the lack of pseudo- vacuoles, are sufficient for identification. Rare. Found in a Sphagnum bog and in pooled streams. Wis. MARSSONIELLA Lemmermann 1900d, p. 275 A colony of 8-12 ovoid or pyriform cells, radiately arranged, with their narrow ends directed outward, inclosed by a thin, transparent, scarcely discernible investment (usually requiring a stain to demon- strate). Marssoniella elegans Lemmermann 1900d, p. 275 P]. 107, Fig. 12 Characteristics as described for the genus; cells 1.3-5p in diam- eter, 5-6 long. Euplankter. Mich. [ 471 ] GOMPHOSPHAERIA Kuetzing 1836, Dec. XVI, No. 151 A globose or ovate colony of globular or pyriform cells arranged singly or in pairs at the ends of gelatinous strands which radiate from a common center, the cells at the periphery of a colorless, mucilaginous envelope; individual sheaths of the cells usually con- fluent. Following cell division in this genus, the cells lie side by side in pairs (or in 4’s) for some time. The division is accompanied by a forking of the stalk at base of cell, which thus forms the radiating branched stalks of the colony. The cells, especially in some species, appear heart-shaped because fission begins at the outer, free pole of the cell, whereas division of the attached end of the cell is delayed. Key to the Species Cells 4-12 in diameter (some varieties smallen))wpyxitonm oncordate =). = SIRES NRE ae G. aponina Cells 1.5-2.44 in diameter, spherical or somewhat reniform G. lacustris Gomphosphaeria aponina Kuetzing 1836, Dec. XVI, No. 151 Pl. 106, Fig. 5 Cells pyriform, or cordate in stages of division, arranged at the periphery of a globular and usually wide gelatinous sheath, and at the ends of stout radiating, gelatinous strands; cells 4-5y in diam- eter, 8-12, long. Tychoplankter; common in many lakes. Mich., Wis. Gomphosphaeria aponina var. cordiformis Wolle 1882, Bull. Torr. Bot. Club, 9, p. 25 PI? 106), Fig:'6 Cells decidedly cordate, compactly arranged within a thick gela- tinous envelope, individual sheaths distinct; cells 6-12» in diameter, 12-15—-( 20)» long. Occurring with the typical plant. Mich., Wis. Gomphosphaeria aponina var. delicatula Virieux 1916, p- 69 Pl. 106, Fig. 7 A variety differing from the typical by the smaller size of the cells, which are 2-3.51 in diameter, 4.5-6. long; colonies globose or ovate and often lobed. Euplankter; uncommon. Wis. [ 472 ] Gomphosphaeria aponina var. gelatinosa Prescott in Prescott, Silva, & Wade 1949, p. 89 Pl. 106, Fig. 10 Cells pyriform, arranged in 2’s and 4's in multiple, irregularly lobed or vermiform colonies, each group of cells entirely or partially enclosed by a thick gelatinous integument, the radiating gelatinous strands common to the typical form not in evidence; cells 3.7—4p in diameter, 6-7.4, long. This variety should be compared with Gomphosphaeria aponina var. multiplex Nygaard. Plankter; in soft water lakes. Wis. Gomphosphaeria lacustris Chodat 1898, p. 180 Pl. 106, Fig. 9 Cells spherical or sometimes reniform, arranged in clusters of 4-8 individuals at the ends of fine gelatinous strands, clusters at some distance from one another in copious gelatinous envelopes; cells 1.5-2.4u in diameter. This species is sometimes abundant as a euplankter, but it is more commonly found among other algae in the tychoplankton. Although generally distributed, this species seems to prefer hard or semi-hard water lakes. It should be compared with Coelosphaerium Kuetzing- ianum. Euplankter. Mich., Wis. Gomphosphaeria lacustris var. compacta Lemmermann 1900, p. 339 | Pl. 106, Fig. 8 Cells oblong, very compactly arranged within a wide, gelatinous envelope, 1.5-2.0, in diameter, 4-6» long. Rather common in the euplankton of both hard and soft water lakes. Wis. GLAUCOCYSTIS Itzigsohn, No. 1935 in Rabenhorst 1866, Die Algen Europas; emend. Geitler 1923a A colony of 4-16 cells inclosed by the persistent mother cell wall (as in Oocystis); cells spherical or ellipsoidal, containing numerous vermiform or sometimes irregularly shaped chromatophore-like bodies which may be either peripheral or somewhat radiating and axially arranged. This interesting plant is now interpreted by most students of algae as a colorless member of the Oocystaceae (Chlorophyta ) containing protoplasts which belong to the Chroococcaceae. It is a little- [ 473 ] understood genus and rather rare, although some species seem to be widely distributed. There appears to be some confusion in the records of the plants assigned to the type species, G. Nostochin- earum. Evidence at hand appears to warrant the separation of spherical from elliptical plants and the assignment of only the latter to the type species if they possess vermiform, radiating “chromato- phores. See Geitler (1923a) and Hieronymus (1892a) on the morphology of these plants. Key to the Species Ms Gels ellijascic atl sas celses 0 ee Dae ee hE SO 2 ly: elisesplherica es sia otec22 Magla Sao 2 eo eS one Eee G. duple 2. Cells broadly elliptical with nodular thickenings at the poles® :..0i\ eis oc Uw y PE See ie eee G. oocystiformis 2. Cells elliptical, without nodular thickenings ab tne ppOles aime ki ss see NEE ute Ee) Sates Fe oe G. Nostochinearum Glaucocystis duplex Prescott 1944, p. 371 PI. 108, Fig. 1 Colony composed of 8-16 spherical cells inclosed by a much enlarged spherical mother cell wall; chromatophore-like bodies in the form of 2 stellate masses with long or short vermiform blue- green protoplasts radiating from 2 separate points; cells 40-44, in diameter; colony 150-170, in diameter. This species differs from G. Nostochinearum by its spherical shape and by the dual arrangement of the colored protoplasts. From G. cingulata Bohlin it differs in the morphology of the cell wall. In that species the cells are spherical, but the wall has a median an- nular thickening. The chromatophores are numerous and parietal. Some forms of G. Nostochinearum are described as spherical, but other features which they possess seem to warrant the assignment of the Wisconsin plants described above to a different species. Among dense clots of algae in Manitowish River, Wisconsin. Glaucocystis Nostochinearum (Itz.) Rabenhorst 1868, p. 417 PI. 108, Fig. 2 A free-floating colony of 4-8 elliptical cells inclosed by the old mother cell wall; chromatophores axial and stellate in arrangement, bright blue-green; host cell reproducing by autospore formation; cells 10-18, in diameter, 18—23.4-(28), long; colony of 4 individ- uals up to 50, long. Intermingled with miscellaneous algae in soft water ponds and acid swamps; especially common in desmid habitats. Wis. [ 474 ] Glaucocystis oocystiformis Prescott 1944, p. 372 Pl. 108, Fig. 3 Cells solitary (or in colonies ?), broadly elliptic, with nodular thickenings of the cell wall at the poles; chromatophores numerous, irregular pads at the periphery of the cell about a central, spherical, colorless vacuole (?); cells 20-27.3» in diameter, 40-45, long. This species differs from the others in the shape of cell, the form of the chromatophores, and in its possession of polar nodules. Whether the absence of colonial association or the retention of autospores within the mother cell wall is a constant feature is un- determined, but in all cases observed, the cells were solitary. In the developmental stages of G. Nostochinearum as described by Hieronymus (1892a) the chromatophores show much the same character as exhibited in G. oocystiformis. I have not found examples of the latter species showing any form of chromatophore other than that described. In a pooled stream, northern Wisconsin. GLOEOCHAETE Lagerheim 1883, p. 39 Either a single colorless cell or a group of 2-4 such individuals endophytized by ovate, blue-green protoplasts which form a cup- shaped body within the host cell; colorless cell spherical, with a single long and very fine gelatinous hair; plants inclosed in a copious, homogeneous gelatinous envelope, attached to the walls of fila- mentous algae. The genus is similar to Glaucocystis in respect to its symbiotic composition. The host cell is regarded as a colorless member of the Tetrasporaceae (Chlorophyta). As in the genus mentioned above, the colorless host cell is not well understood and merits a critical study. Gloeochaete Wittrockiana Lagerheim 1883, p. 39 P]. 108, Fig. 9 Characters as described for the genus; cells 4-8» in diameter, usually in groups of 4; gelatinous setae about 20 times the diameter of the cell in length; endophytic cells 1 (or 2 ?), ovoid, forming a blue-green cup within the host cell. Attached to filamentous algae in soft water lakes. Mich., Wis. ORDER CHAMAESIPHONALES FAMILY CHAMAESIPHONACEAE Members of this family are solitary, or gregarious and form families attached as epiphytes or develop as encrusting expansions [ 475 ] on stones, shells, and other submerged objects. In many there is a definite basal-distal differentiation, with the lower part of the cell narrowed to form an attaching stipe. Although cell division is used by a few forms, the characteristic method of reproduction is by endospores (gonidia), i.e., spore-like bodies cut out simultaneously from the entire protoplast or by successive constrictions at the anterior end of the cell. There is but a single genus represented in our collections. CHAMAESIPHON Braun & Grunow in Rabenhorst 1865, p. 148 A slender, club-shaped (sometimes ovate or pyriform) sheathed cylinder from a narrow attaching basal portion, growing epiphytic- ally on other algae or larger aquatics; sheath open at the widened apex when the cell is mature to permit the escape of 1-celled gon- idia (endospores) which are cut off successively from the anterior end of the protoplast; cell contents pale to bright blue-green, homo- geneous; sheath thin (usually), hyaline or yellowish; plants nearly always gregarious and often forming extensive patches and showing all stages of development, the germinating endospores sometimes forming a layer more than one cell in thickness on the substrate. Of the many species recognized for this genus, only three are identi- fiable in-our collections. Key to the Species 1. Cells long and strongly curved from a stipe-like base C. curvatus 1. Cells short, or elongate, straight, not Sironplyicurved {= =. a SiMe ) 2. Entire content of the cell becoming divided to form many gonidia simultaneously C. confervicola 2. Gonidia cut away from the apex of the protoplast by ysuceessive” constrictions SU stb he) te wees C. incrustans Chamaesiphon confervicola A. Braun in Rabenhorst 1865, p. 148 Pl. 108, Fig. 4 Cylindrical to claviform, usually straight, sometimes curved; 1-2 in diameter at the base, 3-9u at the apex; sheath thin, expanded above; 7% to 34 of the protoplast divided to form endospores, which are 2-4» in diameter and which may occur in double series or in groups of 4; plant either solitary or gregarious. Epiphytic on Cladophora and on submerged mosses and other aquatic plants. Wis. Chamaesiphon curvatus Nordstedt 1878, p. 4 Pl. 108, Figs. 5, 6 Several-celled, violet in color, solitary or gregarious, cylindrical, [ 476 ] strongly curved and twisted, sometimes club-shaped, with a narrow, stipe-like base, 3.8—-44 in diameter, 14-65, long. Growing on Drepanocladus in deep water (5-15 m.). Wis. Chamaesiphon incrustans Grunow in Rabenhorst 1865, p. 149 Pl. 108, Figs. 7, 8 Cylindrical, gregarious, usually straight (sometimes slightly curved ), attached to filamentous algae or leaves of aquatic plants; cells 3-6-(8) in diameter, 10-25, long. This plant was found growing on mosses and other vegetation taken from a depth of 30 feet. Mich., Wis. ORDER HORMOGONALES In contrast to the Chroococcales and Chamaesiphonales, plants in this order are filamentous, comprising a “tribe” known as the Hormogoneae, the other orders making up the “tribe” Coccogoneae. The plant may consist of a trichome of cells inclosed by a sheath which is extremely variable in character, or there may be no sheath. In one suborder, the Homocystineae, there is no differentiation of the cells within the trichome, and, also, there may or may not be basal-distal differentiation. In the other suborder, the Heterocy- stineae, there is a specialization of certain cells in the filament to form two types of structures which are of taxonomic value. One of these is the heterocyst, a thick-walled cell, usually somewhat larger and often different in shape from the vegetative cells. The contents are ordinarily homogeneous. In many cells, the wall at either pole is thickened by a plug of mucilage. The heterocyst may be terminal only, intercalary, or lateral to the trichome. Another special cell is the spore or gonidium, sometimes termed akinete. This cell is usually much-enlarged and thick-walled and has an adventitious reproductive function. The presence or absence of the heterocyst and spore, the position of these in the trichome, together with form and size, are all- important in the recognition of species in this order. Heterocysts are incapable of cell division, but they assist in vegetative repro- duction by facilitating fragmentation of the trichome, or by deter- mining points of proliferation of the trichome through branch for- mation. In some forms heterocysts are known to function as spores. Branching of the trichome may be false, or there may be true branching as a result of cell division in two planes. Reproduction by fragmentation of the trichome to form hormogonia is common to nearly all forms, whereas gonidia are employed only in certain families or genera. [ 477 ] Key to the Families 1. Heterocysts lacking; trichomes with or without a sheath; sometimes with several trichomes within a single sheath ._____ OSCILLATORIACEAE 1. Heterocysts present (rarely absent in some genera which are not represented in our collections; see Amphithrix) ___________-_______ 2 2. Trichomes exhibiting true branching (branches arising as a result of cell ‘division’ im) 2iplanes ) 2 = 5 = os ae eee ee eee 8 2. Trichomes exhibiting false branching, or without branches 4 3. Trichomes and lateral branches uniseriate; heterocysts lateral, ysually at the ends of short branches; sheaths confluent __*NosTOCHOPSACEAE 3. Trichomes and lateral branches multiseriate, or if uniseriate with thick, firm sheaths which are not confluent...._-_____ _ STIGONEMATACEAE 4. Trichomes decidedly tapering toward the apex, usually from a basal: lieterocyst,, 202... eR 2 Ate Ee a ee RIVULARIACEAE 4, ‘Tnichomes not) tapering, toward! the apex. =. 5 5. Trichomes with a definite, firm sheath; false branching frequent) 220» sae eae eee SCYTONEMATACEAE 5. Trichomes without a sheath, or with only a thin one; no branching a NOSTOCACEAE SUBORDER HOMOCYSTINEAE Simple trichomes, without cellular differentiations, with dissepi- ments (sometimes granular) except in the unicellular genus Spiru- lina, and usually sheathed. The sliding, spiral, or oscillating move- ment shown by most members is characteristic of this suborder but not confined to it. Trichomes reproduce by fission or by fragmenta- tion (to form hormogonia), sometimes breaking by means of dead cells (necridia), into sections that then increase in length by fission. The suborder comprises 1 family. FAMILY OSCILLATORIACEAE Key to the Genera i) Trichomes’ spiralled or sepularly coiled eS 2 1. Trichomes straight, bent, or entangled, but not regularly coiled _________ 4 9), Wate nonnes vate Gl Gavin Lyngbya (in part) OasTeni hommes wc vvat oui ts ges ti eee ha ere 3 3. Trichomes 1-celled, usually relatively short Spirulina 3. Trichomes much longer, many-celled, with the dissepiments sometimes indistinct..______________-_=______-________ Arthrospira 4. Trichomes without an evident sheath (though hormogonia may sometimes showsa, thinesheath)) es ee eee Oscillatoria ATT GhOmeSnwiAthy alee VAG emits Ske cl knee eae ene 5 5. Sheath containing a single trichome ——-------------—---------------______---- 6 5. Sheath containing several to many trichomes____--____________________- 9 6. Sheaths firm and definite, not sticking to or confluent with sheaths of other/plants= =) = = 2 ee Lyngbya (in part) 6. Sheaths mucous and sticky, confluent with those of other plants, often indefinite i 7. Plant mass forming erect tufts from a horizontal expanse, especially when growing on moist substrates __________ Symploca 7, splantmeasseuoet tOxmnIng erect tures eee ee 8. Trichomes lying parallel, forming planktonic fascicles. Trichodesmium 8. Trichomes entangled, forming mucous, sometimes thick, layers on a substrate________-_-—-____________- Phormidium 9. Sheaths wide, mucous, soft and sticky; freely branching -.________. 10 9. Sheaths firm and narrow; not freely branching; trichomes densely compacted and entwined Schizothrix 10. Trichomes loosely arranged, 2-4 in a sheath —______________-_. Hydrocoleum 10. Trichomes densely entangled, many within a sheath. Microcoleus SPIRULINA Turpin 1827, p. 309 A spirally twisted, unicellular trichome, cylindrical throughout and not tapering toward the apices (although briefly attenuated in some species ); spiral loose and lax, or close and tightly coiled ac- cording to species, the spiral usually very regular; trichomes free- floating and planktonic or intermingled with other algae in tycho- plankton, sometimes forming layers on moist soil, especially where water has subsided. This genus should be compared with Arthrospira, in which the trichomes are multicellular. According to the interpretations of some phycologists the two genera should not be separated. This would seem to be justifiable when the dissepiments of Arthrospira cannot be demonstrated and the trichome appears to be unicellular. See Crow (1927) on the characteristics of these two genera. Key to the Species 1. Trichomes very tightly coiled.____________-_-_-__----__________- S. subsalsa 1. Trichomes loosely coiled. ® 2. Spirals 10-12—(16) or more V1 CL A Wh a ook a Bs 1 S. princeps 2. Spirals less than 10 Sia (a (Rei uea Meche rateable iia oe os ONE er ane 3 3. Spirals 4-6u wide, very 1 GG Se aa ha I eae a bed oa, oe ee 4 3. Spirals averaging less in width, more tightly coiled ALD 4, Trichamerso ue diameters. S. laxa An Rrchome.O.— Ose a Giameter ee S. laxissima 5. Spirals 54 wide; trichomes 2 WiC Gi see ee er ae S. Nordstedtii 5. Spirals 2.5-4u wide; trichomes 1.2-1.7u wide, very long. S. major Spirulina laxa G. M. Smith 1916, p. 481 Pl. 108, Fig. 10 Trichomes loosely spiralled, forming a dark blue-green mass, 2-2.5p in diameter, spiral 4-6. wide; distance between spirals 15-20p wide; cell contents blue-green. Tychoplankter. Wis. [ 479 ] Spirulina laxissima G. S. West 1907, p. 178 PIO Figs Trichomes very slender, 0.7-0.8u in diameter, twisted in a very loose spiral, 4.5-5.31 wide; distance between spirals 17-22»; apex bluntly rounded. Euplankter. Mich. Spirulina major Kuetzing 1843, p. 183 Pl. 108, Fig. 11) Trichomes loosely spiralled, scattered among other algae, or when aggregated forming a dark, blue-green mass; trichomes 1.2-1.7p in diameter; spiral 2.5-41 wide; distance between spirals 2.7-5y. This is a very active species of great length. It is commonly found among Oscillatoria species on soil from which water has recently subsided, or on muddy shores and margins of springs, etc. Wis. Spirulina Nordstedtii Gomont 1892a, p. 252 Pl. 108, Fig. 12 Trichomes rather closely and regularly spiralled, 2» in diameter, spiral 5» wide, distance between spirals 5p; cell contents pale or bright blue-green. Plankter; also found on bottom of soft water lakes discolored by humic acids. Wis. Spirulina princeps (West & West ) G. S. West 1907, p. 179 Pl. 108, Fig. 13 Trichomes loosely spiralled, either straight or bent, 3-5y in diameter; spirals 8.8-16 wide; distance between spirals (9.5)—10- 12-(16),; cell contents bright blue-green, homogeneous or slightly granular. Among other algae in tychoplankton. Wis. Spirulina subsalsa Oersted 1842, p. 17 Pl. 108, Fig. 14 Trichomes both closely and loosely spiralled in the same indi- vidual, 1-2 in diameter; spiral 3-5, wide, often so tightly coiled that there is no space between the turns. Tychoplankter. Wis. ARTHROSPIRA Stizenberger 1852, p. 82 Trichome a long, loosely spiralled, many-celled plant, not at all or only very briefly tapering toward the apex, which is broadly [ 480 ] rounded; sheath wanting; cells quadrate or a little longer than wide, the dissepiments sometimes granular, sometimes scarcely discernible. See note under Spirulina (p. 479). These plants may form thin expansions, but more usually are found intermingled with other algae, especially Oscillatoria spp. Key to the Species TMriGhoOmeseee sa see MTS Ta Te Ce eee A. Gomontiana TrichomeswG—Gusiiciamecter: 200 ee A. Jenneri Arthrospira Gomontiana Setchell 1895, p. 430 PI. 108, Fig. 21 Trichomes very loosely spiralled, entangled to form free-floating flakes, bright blue-green, 2.5-3.2 in diameter; cells 4-5 long, with the dissepiments often scarcely discernible; cell contents vacuolate (?); width of spiral 4-6; distance between turns 16-18»; forming floating patches of much entangled and actively twisting trichomes. Tychoplankter. Wis. Arthrospira Jenneri (Kuetz.) Stizenberger 1852, p. 32 Pl. 108, Figs. 22, 23 Trichomes blue-green, scattered or gregarious, loosely coiled, not tapering toward the apices, 6-8, in diameter; cells quadrate, dis- sepiments granular, 4-5» long; spiral 10-15, wide, distance between turns 12-14n. Intermingled with other Cyanophyta filaments on mud, or in organic sediment which has collected on submerged plants. Com- mon. Mich., Wis. OSCILLATORIA Vaucher 1803, p. 165 Filamentous and elongate, without a sheath (except in hormo- gonous stages of filament development); straight, or twisted and entangled; the mature plant showing a polarity with an apical region, which is often attenuated, the basal end truncate; trichomes solitary and scattered, or forming expanded plant masses and slimy layers on submerged objects or on the bottom; microscopically usually showing an oscillating or gliding movement, especially active in the anterior portion of the trichome; apical cell smoothly rounded, or swollen and capitate, sometimes with a distinct sheath- like membrane, the calyptra; most species having cells much shorter than their width, with or without constrictions at the cross [ 481 ] walls, which sometimes have a row of granules on either side; plants often living under semi-anaerobic conditions in stagnant water. In examining species of Oscillatoria care must be used not to confuse them with Phormidium, a genus in which there are sticky but sometimes very thin sheaths, which are best seen by stainin with an aqueous dye or with chlor-zinc-iodide (see Drouet, 1937). Key to the Species i. Trichomes':10p.0r more imidiameter= see te es ee, 2 i> Erichomeswlessithany Oj oin. diameters. eet ake eee 8 2° Triehomes :25—80n) intdiameter =.= BO a ae O. princeps 2) Trichomessmallers) 222 /or less in. diameters ie es 3 3. Cells almost colorless, with large, conspicuous AI COMMON VACUOLES 2h 2s eae Rian pi Nan) A ale eae Does ey O. Bornetii 3. Cells definitely pigmented, without conspicuous alveoli, although’ sometimes; with pseudovacuoles_= 4 4 4, trichomes) constricted at the cross walls\2- =) ta ey 5 4. Trichomes not constricted at the cross walls === a 5. Trichomes slightly capitate at the apex, with a calyptra_..____ O. sancta Sawirichomes mat teapitate, withoutia: calyptra == os Cat eh 6 6. Trichomes not tapering at the apex; cells very short less/thany+$-as long, as broad —-=_ = O. ornata 6. Trichomes tapering at the apex; cells 14 OPMMOre, ass lompras sblOad) aaa tne Y wards alee Bee ee ee Mal O. chalybeu aA EI MOTHIESe IS tha LG Ib en toe fare io th ee Ae ee eee O. limosa i} Erichomesshookedsatithe apextcass =e J 8 By deen . eet a, O. curviceps SabrichomesnO!6—2/0 aiminci amie ter eee eee ee ae aes eae nee 9 8:5 Drichomes (2) =2-2—l0 a. in. diameter = 2 a es wo ee 13 GO} airichomes: 0:6—1e8icim diameter-e- ss es eee e es e 10 9) trichomes: 175-24 in diameters es ee ee ee ene itil 10. Trichomes 0.64 in diameter, 1-1.84 long... O. angustissima 10. Trichomes 0.8—1.3u in diameter, 5—7u long. O. angusta 11. Plants golden-colored, coiled, 2u in diameter____-___-_»___> O. minima 11. Plants blue-green or olive-green, straight, 1.5-1.8—(2)u in diameter. 12 12. Trichomes tapering at the apex, and bent.______________. O. acutissima 12. Trichomes not tapering at the apex, straight O. limnetica 13. Trichomes with cross walls very much thickened, sometimes nearly equalling the length of the cell cavity_______ O. articulata 13. Trichomes without conspicuously thickened cross walls... 14 14. Plants planktonic and purplish or red, usually, coloring :the, water 24s. Se se O. rubescens 14. Plants planktonic or not, but not purple On ed: anid, notacolormmgy the water.) 7 ses. es eee eee 15 IS, Dine nvorines, Qs syn. iim Ghiewnelier 16 Ns, ANmtelvomas NO, tm, ligne 26 16) Apical cellcapitate;;usually with a calyptras = = eee 17 16 4-Apical’ cell wotica pitake, ==. pe. 2 oad es ee 21 17. Trichomes slightly constricted at the cross walls...................... O. amoena 17. Trichomes not constricted at the cross walls _______»___-_______ 8 18. Trichomes tapering for a long distance in the apical region. O. splendida 18. Trichomes not at all or only briefly tapering in the apical region__________ 19 [ 482 } ») Gellsienanulaniat the’ cross walls. 0s... eee eee O. Agardhii . Cells not granular at the cross walls (rarely granular)..................... 20 . Apicalvee!liiwath a flattened ‘calyptra = Sees Ee O. prolifica . Apical cell with a cone-shaped calyptra___________________. O. amoena . ‘richemes tapering in, the apicaliregion 252 2 Set ea 2D .. Dnichomes mot tapering in the apical regions 23 2 24 » Frichomestsmaughtsthronghout (ste Spee eee O. Agardhii . Trichomes twisted and bent, or straight in the basal portion and hooked orreumvediatrthe apex i222 9a: jhe 23 . Trichomes crooked or spirally twisted at the apers, crossswalismmot pramulars 2 = O. terebriforinis . Trichomes curved but not hooked or twisted at the’ apexvierosstwallsupranular 2. 20102 O. granulata )) \Cellssnotiexanularwaptheteross walls 1.222 ee O. subbrevis -. Cells, withidistictly. granular cross’ walls 2. = 25 . Cells with rows of granules at the cross walls_____________________ O. tenuis . Cells with 1 or 2 conspicuous granules at the cross walls O. amphibia : “Apical cell capitate; usually with a calyptra Dy ay Apicalicell ot capitate ten es ee ee eee 29 . Trichomes bent or hooked at the apex, forming a plant mass __ O. anguina . Trichomes scattered in tychoplankton or euplankton, straight —_._ _. 28 . Cells 6—8u in diameter, trichomes usually scattered, appearing red or purple when in bundles —_-____________- O. rubescens . Cells 4—6u in diameter, trichomes solitary, or, when in bundles, appearing blue-green. _..O. Agardhii Reiinichomies, Sbraiplit 22.0 eee 80 . Trichomes spirally twisted, undulate, or at leastuhooked orfeurvedatythejapexs = 6a. eh ee 36 . Trichomes constricted (sometimes slightly) at the cross walls............ 34 . Trichomes not constricted at the cross wallls..............0.....0.0.cceccssenee 31 Strichomes mot appeanmp: ted or purple 2 32 . Trichomes appearing red or purple, coloring the water when abundantly present; solitary or in bundles _________________-_-------- O. rubescens . Cells 8—9.2—(10)» in diameter (sometimes curved at the apex). O. nigra MECC) s 4.3.5) => — Oe ine RaNeLer see 83 . Cells granular at the cross walls, with pseudovacuoles —__. O. Agardhii . Cells not granular at the cross walls, without pseudovacuoles__O. subbrevis . Trichomes in parallel, free-floating bundles _____________-- O. lacustris . Trichomes not in parallel, free-floating bundles___________________--____--_--- 85 pe@ellsslome: cy lita Gri Call qs ee a O. Hamelii ; Gells shorter than wide, or about quadrate_ = 2 O. tenuis Bi@ellsmongacylindrical = See es sie O. Hamelii . Cells shorter than wide, or slightly longer tianebroad:, but nearly quadnate see 87 Rerichomes .6—9—( 10) ya: amy chamleten ess = ee 38 , Ihatelrornas leostdeain Gyn tin Clerc 2 40 . Trichomes crooked and much twisted in the apical region ________- O. ornata . Trichomes regularly curved at the apex (often shraishior only slightly bent see een ee 39 . Cells granular at the cross walls, very little or Sometimes Ot at all constricted= === es O. nigra . Cells not granular at the cross walls, definitely constrctedsatithe cross walls 25 sees os Pt O. chalybea 40) Trichomesstapering ‘atithe. apex 22). a0. nk See A 4l 40. Drichomes moe tapering: at the apexsss. == eames en een es O. nigra 41. Trichomes crooked and undulate at the apex; not constricted at ‘the cross.walls = 222) = eee O. terebriformis 41. Trichomes curved at the apex, sometimes straight; constricted iat the cross.walls: oo! eed O. formosa Oscillatoria acutissima Kufferath 1914, p. 264 Pl. 109, Fig. 1 Trichomes solitary and scattered, or loosely entangled in the mucilage of other algae; gradually tapering to the apex, which is curved or bent slightly. Apical cell acute-conical, with a calyptra. Cells 1.5-2, in diameter, 114 to 3 times longer than wide; not con- stricted at the cross walls, which are not granular. Although I have not seen type specimens of O. acutissima, I have assigned our plants to this species on the basis of their agreement with Kufferath’s description. Tychoplankter; in mucilage of colonial diatoms and egg masses. Mich., Wis. Oscillatoria Agardhii Gomont 1892a, p. 205 Pl. 108, Figs. 15, 16 Trichomes interwoven to form a blue-green plant mass; occasion- ally found floating free; straight throughout their entire length, briefly tapering at the anterior end, which is usually capitate, but frequently smooth. Apical cell truncate-conical, with or without a calyptra. Cells (3.4)-5.5-6, in diameter and not constricted at the cross walls, which are granular; their length from 1% to approxi- mately equal their width (sometimes 114 times their width in length). This species shows a great deal of variation in the morphology of the apex of the trichome. The straight interwoven filaments, the cell proportions, and the granular cross walls help to identify it. Abundant in tychoplankton; generally distributed. Mich., Wis. Oscillatoria amoena (Kuetz.) Gomont 1892a, p. 225 Pl. 109, Figs. 2-4 Trichomes usually forming a thin, submerged, weft-like, blue- green mass, or sometimes scattered among other algae; usually straight but not rigid, slightly tapering toward the apex. Apical cell broad, capitate, with a cone-shaped calyptra. Cells (2.5)—4-5p in diameter, 2.5—4.2u long; usually slightly constricted at the cross walls, which are granular. In tychoplankton of littoral flora; in springs. Mich., Wis. [ 484 ] Oscillatoria amphibia C. A. Agardh 1827, p. 632 Pl. 109, Fig. 6 Trichomes straight or curved and interwoven to form a thin, blue-green plant mass on submerged objects or in moist aerial habi- tats; not tapering toward the apex. Apical cell broadly rounded, smooth, with a convex outer membrane. Cells (1.5)—2-2.8-(4), in diameter, 2-4 times their diameter in length (4-8); not constricted at the cross walls, which have a single large granule on either side, a series of paired granules showing throughout the length of the trichome. In shallow water of lakes, ponds, and swamps; on submerged objects. Mich., Wis. Oscillatoria anguina (Bory ) Gomont 1892a, p. 214 Pl. 108, Fig. 24 Trichomes entangled and interwoven to form a dark green plant mass on submerged objects, or intermingled among other algae; straight for most of their length but bent and sometimes twisted in the apical region, slightly tapering toward the apex. Apical cell slightly narrowed and capitate, with a thickened outer membrane. Cells 7-8 in diameter, short, as little as 4% of their diameter in length; not constricted at the cross walls, which are granular. Swol- len refringent cells common throughout the length of the trichome. Forming films on bottom in shallow water. Wis. Oscillatoria angusta Koppe 1924, p. 641 Pl. 109) Fig, if Trichomes loosely entangled to form a thin plant mass, or solitary; not tapering toward the apex; apical cell bluntly rounded, without a calyptra and not capitate; cells (0.8)-1.1-1.3y in diameter, (5)— 7-8-(10), long, not constricted at the cross walls; contents nearly colorless, without pseudovacuoles or conspicuous granules. Entangled and intermingled with other species of Oscillatoria and miscellaneous blue-green algae, forming a slimy layer in shallow water. Wis. Oscillatoria angustissima West & West 1897, p. 300 PI. 109, Fig. 5 Trichomes much entangled to form a thin, light blue-green plant mass, not tapering toward the apices; apical cell bluntly rounded, not capitate and without a calyptra; cells 0.6-1.0y in diameter, 1144- 3 times their diameter in length; not constricted at the cross walls, [ 485 ] which are scarcely discernible, especially in the anterior end of the trichome; cell contents almost colorless. This is the smallest species of Oscillatoria appearing in our col- lections. It is easily mistaken for a filamentous bacterium because of its size and pale color. In mass, however, it clearly shows its blue-green algal identity. Not infrequently this species is found en- tangled in the mucilage of colonial Cyanophyta. Tychoplanktonic and euplanktonic. Mich., Wis. Oscillatoria articulata Gardner 1927, p. 34 [Oscillatoria Grunowiana var. articulata (Gard. ) Drouet] Pl. 107, Fig. 22 Trichomes entangled, flexuous, forming a thin blue-green plant mass, or scattered among other algae, not tapering to the apices; apical cell rounded, not capitate and without a calyptra, but with a thickened outer membrane; cells 2.8-3.2 in diameter, quadrate or 44-14 as long as broad, not constricted at the cross walls, which are conspicuously thickened, sometimes as much as the length of the cell cavity. Mich. Oscillatoria Bornetii Zukal 1894, p. 260 Pl. 108, Figs. 19, 20 Trichomes forming a slimy, expanded plant mass, or intermingled among other algae; more or less straight but often bent or slightly sigmoid in the apical region, not tapering toward the apex. Apical cell smoothly rounded, not capitate, and without a calyptra. Cells (10)-12-16, in diameter, 3.744 long; not constricted at the cross walls; cell contents pale, almost colorless, with large quadrangular alveolations or vacuoles. Tychoplankter; in lakes and slowly flowing water. Wis. Oscillatoria chalybea Mertens in Jiirgens 1822, Dec. 18, No. 4 Pl. 109, Figs. 8, 9 Trichomes aggregated to form a dark blue-green plant mass; straight for a portion of their length but much entangled and some- times spirally twisted, gradually tapering toward the apex. Apical cell conical, with a smooth, unthickened outer membrane. Cells (6)-8-12-(13) in diameter, 4-6.8, long; slightly constricted at the cross walls, which are not granular. Tychoplankter. Mich., Wis. [ 486 ] Oscillatoria curviceps C. A. Agardh 1824, p. 68 Pl. 108, Figs. 17, 18 Trichomes forming an expanded blue-green plant mass; straight for at least a portion of their length, twisted and much entangled, scarcely tapering to the apex. Apical cell broadly rounded, not capitate, without a calyptra. Cells 10-14-(17), in diameter, 3-5y long; not constricted at the cross walls, which may be granulate. Forming floating clots; tychoplanktonic. Mich., Wis. Oscillatoria formosa Bory 1827, p. 474 Pl. 109, Figs. 10, 11 Trichomes aggregated to form a dark blue-green plant mass; straight and rather firm, curved and slightly tapering toward the apex. Apical cell conical, not capitate, without a calyptra. Cells 4-6 in diameter, 2.5—5, long; constricted at the cross walls, which are granular. Rather common on wet soil at margins of lakes, and about swamps; tychoplanktonic in shallow water of ponds. Mich., Wis. Oscillatoria granulata Gardner 1927, p. 37 Pl. 109, Figs. 12, 13 Trichomes aggregated to form an expanded plant mass; straight or somewhat curved, especially at the apex, which is slightly atten- uated. Apical cell not capitate and without a calyptra. Cells 3-5 in diameter, 14-114 times their diameter in length; not constricted at the cross walls, which are distinctly granular. Occurring as small, slimy flakes, or scattered among other algae. Wis. Oscillatoria Hamelii Frémy 1930, p. 218 Pl. 109, Fig. 14 Trichomes solitary among other algae, or sparsely aggregated to form blue-green masses; straight or undulate, not attenuated at the apices. Apical cell truncately conical, without a calyptra. Cells 7.2-8.5 in diameter, 114-2 times the diameter in length; distinctly constricted at the cross walls, which are not granular. This plant is assigned here on the basis of its agreement with Frémy’s description. The type habitat of O. Hamelii is in Africa, but the universal distribution of many species of the genus makes its appearance in North America not unusual. Forming a film on dead leaves in a stream. Wis. [ 487 ] POscillatoria lacustris (Kleb.) Geitler 1925a, p. 362 [Trichodesmium lacustre Klebahn 1895, p. 13] Pl. 109, Fig. 15 Trichomes straight, lying parallel in free-floating, flake-like bun- dles or fascicles, not tapering at the apices; apical cell broadly rounded, without a calyptra; cells compressed globose or barrel- shaped, sometimes semiquadrate, or a little longer or shorter than wide, 5-7» in diameter, 3-7» long; cell contents with many pseudo- vacuoles. The specimens assigned here are enigmatic. The bundles of trichomes strongly suggest Trichodesmium because of their arrange- ment and lack of heterocysts. They are not like Trichodesmium lacustre Klebahn, however, in respect to the morphology of the apical cell which in that species is long and attenuate, but which in our specimens is short and rotund. The suggestion has been made that the plant found in our collections is a juvenile form of Aphani- zomenon, which would appear reasonable because of the similarity in respect to trichome arrangement, cell shape, and cytology. As I have pointed out elsewhere (1942, p. 665), however, the occurrence of these bundles of trichomes in what certainly appears to be a mature condition and without any suggestion of nostochaceous characters (heterocysts, gonidia), precludes such a disposition. Geitler has assigned Klebahn’s species to Oscillatoria and relegates the Wisconsin plant previously reported by Smith (1920) to Aphani- zomenon. There is scarcely enough evidence at present to justify giving a new name to the Wisconsin plant, but it is possible that subsequent study will establish it as a new fresh-water species of Trichodesmium. Plankter; in hard or semi-hard water, especially eutrophic, lakes. Wis. Oscillatoria limnetica Lemmermann 1900, Ber. d. Deutsch. Bot. Ges., 18, p. 310 Pl. 109, Fig. 16 Trichomes solitary and planktonic or intermingled with other algae in littoral waters; straight or flexuous, not tapering toward the apex. Apical cell bluntly rounded and without a calyptra. Cells 1.5-1.8 in diameter, 314 times the diameter in length; not con- stricted at the cross walls, which are scarcely visible and are not marked by granules. In shallow water of swamps and bogs; among submerged aquatics. Wis. [ 488 ] Oscillatoria limosa (Roth) C. A. Agardh 1812, p. 35 PIZLOS) Pig7 Trichomes usually forming a very dark blue-green or brownish plant mass attached to submerged objects or forming films on sandy bottoms, although rarely solitary or loosely entangled among fila- mentous algae; straight, tapering little or not at all toward the apex. Apical cell rotund, the outer membrane thickened but without a definite calyptra. Cells 12-18—(20) in diameter, 3.7-5y long, not constricted at the cross walls, which are usually granular. Trichomes not infrequently inclosed in a hormogonous sheath. Common in stagnant water of ditches and small ponds; tycho- planktonic in lakes. Mich., Wis. Oscillatoria minima Gicklhorn 1921, p. 4 Pl. 107, Fig. 24 Trichomes somewhat coiled and spirally twisted, golden-colored, inclosed in a delicate mucilaginous sheath, not tapering toward the apex; apical cell not capitate and without a calyptra; cells 2 in diameter, 5-6, long. Mich. Oscillatoria nigra Vaucher 1803, p. 192 Pl. 109, Fig. 18 Trichomes aggregated to form a thick, mucilaginous blackish- green plant mass on submerged objects, becoming free-floating; straight or slightly twisted and entangled, slightly tapering toward the apex and curved (or straight). Apical cell rotund, not capitate and without a calyptra. Cells 8—10y in diameter, 3.7—4.5, long; slightly constricted at the cross walls, which are sometimes gran- ular; cell contents dark olive-green. Common in the shallow water of many lakes and ponds. Mich., Wis. Oscillatoria ornata Kuetzing 1845-1849, p. 30 Trichomes forming a dark, blue-green plant mass; spirally twisted at the end, not at all or scarcely tapering toward the apex. Apical cell broadly rounded, not capitate and without a calyptra. Cells 9-11p in diameter, short, 14-14 times as long as broad (2-5p long), constricted at cross walls which are granular. Mich. Oscillatoria princeps Vaucher 1803, p. 190 PE L110; Fig. 1 Trichomes solitary or loosely entangled to form small floating plant masses, which are black-green in color; individual plants [ 489 ] visible to the unaided eye; trichomes very slightly and briefly taper- ing at the apex. Apical cell usually not capitate, sometimes very slightly so, the outer membrane broadly convex and smooth. Cells 32-55—(80)» in diameter, 4-8.71 long; not constricted at the cross walls, which are not granular; cell contents densely granular. Common in tychoplankton of a variety of lakes and small ponds; in marshes. Mich., Wis. Oscillatoria prolifica (Grev.) Gomont 1892a, p. 205 Pl. 110, Figs. 2, 3 Trichomes aggregated to form a floating, purple-black expanded mass; straight, but flexible, slightly tapering toward the apex. Apical cell capitate, with a broadly flattened calyptra. Cells 2.5-5, in diameter, 4-6, long, without constrictions at the cross walls, which are sometimes granular; cell contents densely granular. Plant described as becoming lilac-colored upon drying. Tychoplanktonic and euplanktonic. Mich., Wis. Oscillatoria rubescens De Candolle 1825, Mém. Soc. Phys. Nat. Geneve, 2, p. 29 Pl. 107, Fig. 21 Trichomes solitary or forming small fascicles, appearing red or purple in the plankton; very slightly if at all tapering toward the apex. Apical cell often capitate, with a calyptra, but (in our speci- mens ) as often broadly rounded and smooth. Cells 6-8 in diameter, 2-4» long; not constricted at the cross walls, which are usually granular; cell contents with pseudovacuoles. Our specimens definitely appear to belong to this species, but the lack of capitate apical cells in most plants observed, and the non-tapering trichomes are in disagreement with the original de- scription. Euplanktonic and tychoplanktonic. In hard water lakes of south- ern Michigan; forming blooms during late winter immediately after the disappearance of ice. Oscillatoria sancta (Kuetz.) Gomont 1892a, p. 209 Pl. 110, Fig. 4 Trichomes aggregated to form a dark gray-green plant mass (in our collections), usually on submerged vegetation; straight, not at all or scarcely tapering toward the apex. Apical cell somewhat capitate, with a calyptra, and with a much thickened outer mem- brane. Cells 11—13—(20)» in diameter, 4—5y long; slightly con- stricted at the cross walls, which are conspicuously granular; cell contents coarsely granular, olive- or gray-green in color. On submerged aquatics. Mich., Wis. [ 490 ] Oscillatoria sancta var. aequinoctialis Kuetzing 1845-1549, p. 30 A questionable variety, with a diameter in the upper limits of the species range (14~-20,). Mich. Oscillatoria splendida Greville 1824, p. 305 Pl. 110, Figs. 5-7 Trichomes solitary and scattered, rarely aggregated in small, flake-like masses; straight or curved, tapering for a long distance to a fine hair at the apex. Apical cell conical and capitate. Cells 2.2-2.8 in diameter, 7.2-9» long, not constricted at the cross walls; cell contents finely granular or homogeneous, pale blue-green. Common in a variety of lakes with a high pH; generally distrib- uted. Mich., Wis. Oscillatoria subbrevis Schmidle 1901b, p. 243 Pl. 107, Fig. 23 Filaments solitary, not occurring in a plant mass; straight and not tapering toward the apices. Apical cell rounded, not capitate and without a calyptra. Cells short, 5-6 in diameter, 1-2 long, with frequent necridia in evidence; cross walls not granular; cell contents pale gray-green. Mich. Oscillatoria tenuis C. A. Agardh 1813, Algarum Decades, p. 25 Pl. 110, Figs. 8, 9, 14 Trichomes aggregated to form a blue-green mass, sometimes be- coming scattered and appearing singly among other algae. Straight or slightly flexuous, especially at the anterior end, which does not taper; hormogonous sheath frequently present. Apical cell convex, smooth, and not capitate; outer membrane sometimes slightly thick- ened. Cells (4)-5-8-(10)» in diameter, 2.5-3.2-(5)y long; con- stricted at the cross walls (sometimes only slightly so), which are granular. Generally distributed and very common in tychoplankton of a variety of lakes and ponds; in swamps and roadside ditches. Mich., Wis. Oscillatoria tenuis var. natans Gomont 1892a, p. 221 Pl. 110, Figs. 10, 11 A variety differing from the typical by having stouter trichomes (in our specimens), which are 7.4-10, in diameter; cells 3.44.6 long; apical cell truncately rounded. [ 491 ] Forming a blue-green algal film on the bottom; tychoplanktonic. Wis. Oscillatoria tenuis var. tergestina (Kuetz.) Rabenhorst 1865, p. 102 PH WMO Wigs i213 A variety differing from the typical by its smaller proportions, 5.56 in diameter; apical cell convex or cone-shaped. Drouet (1938, p. 269) states that both this variety and var. natans may be found in the same collection, suggesting that the differences in size hardly justify the use of two varietal names. Gomont in his monograph (1892, p. 221) recognizes the variety. Euplanktonic and tychoplanktonic. Wis. Oscillatoria terebriformis C. A. Agardh 1827, p. 634 Pl. 107, Figs. 25, 26 Trichomes forming a plant mass, dark steel-blue in color; spirally twisted, especially at the apex, slightly tapering in the apical region. Apical cell round or pointed, not capitate, and without a calyptra. Cells 4-6.5y in diameter, 2.5-6 long; not constricted at the cross walls. Mich. PHORMIDIUM Kuetzing 1843, p. 190 Plant mass consisting of simple, unbranched filaments within agglutinated and diffluent sheaths which form mucilaginous layers or penicillate tufts (streaming in flowing water). Trichomes cylin- drical throughout, except for a slight and brief tapering in the apical region; either parallel or entwined. Apical cell conical, blunt- pointed or capitate, with or without a calyptra. Individual sheaths usually indistinct and difficult of demonstration, although the diffluent sheaths of the plant mass are clearly in evidence. Cells shorter than wide, or quadrate; constricted at the cross walls in some species. Under certain conditions of preservation the sheath structure of species in this genus may become so difficult of demonstration that it is possible to confuse them with some forms of Oscillatoria. It is the sheath which fundamentally separates the two genera. In the field and in macroscopic appearance they may be differentiated usually on the basis of the compact, felt-like layer constructed by Phormidium. Whereas masses of some species of Oscillatoria may form somewhat similar mats, the trichomes dissociate easily when the collection is made. In Phormidium, the mat when present is compact and does not dissociate. [ 492 ] Key to the Species 1. Trichomes short, living within the mucilage of other Cyanophyta (e.g. Microcystis )...........::c1eciee P. mucicola 1. Trichomes long, forming plant masses, not living within the mucilage of other algae...................0:: eee 2 2. Trichomes with constrictions at the cross walls ..............0..:::ccees 3 2. Trichomes without constrictions at the cross walls.........0....00.0ccs 6 3° Trichomes capitate at the apex. cccgceccceecs tenn see cet ee coc eeeeencneteganeenss P. lucidum Sh Trichomes: mae Gapitate sie tee ee eee ence oon cece seascape oanestaaaee 4 4, Apical cell decidedly tapering and elongate 20.0.0... P. tenue 4. Apical cell not elongate, not or slightly tapering ............0.- es 5 5. Cells 2.5m in diameter, 2—4u long ...............cccceeeee P. minnesotense B@ells 426) in wiameters 1220 by WOM oto as. fa.se sens ewe secre: P. ambiguum 6. Trichomes decidedly twisted or hooked at the apex.............. P. uncinatum 6. Trichomes not twisted, straight or slightly curved at the apex............ 7 @. Apical “cell (capitate oc: ocoe cece ccs saceceterre erence aeons tecncbeveswerecracnenne edenes tanec 8 7. Apical’ cell not Capitate 3 pce seek tape ae anata esate ona 11 8. Trichomes with a conical, sharply pointed calyptra........ P. Setchellianum 8. Trichomes with a broadly rounded or convex calyptra.................0-+. 9 Gili hones? est reli gitar ees eee ese eee ac ote teed aera =ciaia 10 Ge kmchomies scurved. clexmwous ) eect terete ace ret rer eee: P. autumnale 10: Gells longer ‘tham wide ji )-0:2.3:5-20e 2 beeaecacon cece O00 eer veges neces P. favosum 1OksGellseshorter thane pwidese., 2 eres et neat new esterase: P. subfuscum 1 ‘Plant mass incrusted wath lime (2.222. 4-.c...5-6: 222 -casecnnsoee ee P. incrustatum ldewPlant- mass not ameristed) with ‘Mintel 2) oe. cect ce secneccenceersene see re os a 12 PIG rossi walls cerani lane oe. Bee -tosc ten. ccna ote pone ences ed P. inundatum Se ransecyralll's is carob rene aN a sce eh geet veneers are sese send gases as 13 13. Trichomes curved; cells 3—4.5u in diameter, 3.4—8» long ....... P. Corium 13. Trichomes straight; cells 4.5—12u in diameter, PNET VPP (yas a el nea eee Pd ne cee Pence nome Pc ree P. Retzii Phormidium ambiguum Gomont 1892a, _p. 178 PL Big Filaments forming a blue-green, mucilaginous layer; straight or gracefully curved, either parallel or somewhat entwined; individual sheaths usually distinct and lamellate but becoming confluent with the mucilage of the plant mass; trichomes curved or rarely straight at the apices, which are not tapering; apical cell broadly rounded, not capitate, but with a thickened outer membrane, which may give a slightly pointed appearance; cells short, disc-like constricted at the cross walls, 4-6 in diameter, 1.2—2.7 long; cell contents finely granular. Among other algae and floating free in tychoplankton. Wis. Phormidium autumnale (C. A. Ag.) Gomont 1893, p. 207 Pl. 107, Figs. 19, 20 Plant mass forming a broadly expanded, dark-green, mucilaginous layer; filaments much entangled but may be either straight or curved and flexuous; sheaths at first distinct, becoming diffluent [ 493 ] and confluent with the mucilage of the plant mass; apex slightly tapering, either straight or somewhat curved and capitate, with a calyptra; cell contents blue-green; cells 4-7 in diameter, 2-5» long, not constricted at the cross walls, which are granular. Mich. Phormidium Corium (C. A. Ag.) Gomont 1890, p. 355 Filaments compactly intertwined and entangled to form a soft but tough membranous layer, dark bluish-green to black; sheaths thin and becoming confluent with the mucilage of the plant mass, trichomes curved (or straight) and slightly tapering at the apex, but not capitate and without a calyptra; cells 3-4.5, in diameter, 3.48 long, not constricted at the cross walls; cell contents granular. Mich. Phormidium favosum (Bory ) Gomont 1892a, p. 180 Pl. 111, Fig. 2 Filaments forming a dark green expanded, thin or thick plant mass; individual sheaths not clearly evident; trichomes straight or flexuous and sometimes coiled in the distal region which tapers slightly; apical cell capitate, with a conical or hemispherical calyp- tra; cells 4.5-9, in diameter, 3-7 long, not constricted at the cross walls but with a double row of granules at the partitions; cell con- tents blue-green. In trough, at Osceola, Wisconsin. Phormidium incrustatum (Naeg.) Gomont in Bornet & Flahault 1889, p. CLIV Filaments forming a dark red or violet stratum, encrusted with lime. Trichomes parallel, or curved and entangled in thin mucous sheaths; straight at the apex and tapering slightly, not capitate. Apical cell obtuse-conical. Cells quadrate or slightly longer than wide; not constricted at the cross walls, which are sometimes gran- ular; 4-5p in diameter, 3.5-5.2 long. In a stream at Osceola, Wisconsin. Phormidium inundatum Kuetzing 1849, p. 251 Pl. 111, Fig. 3; Pl. 107, Fig. 15 Filaments forming a blue-green, gelatinous, membranous expan- sion; individual sheaths scarcely discernible, diffluent. Trichome straight and parallel, tapering at the apices to form a conical apical cell, which is not capitate. Cells quadrate or short-cylindric, 3-5 [ 494 ] in diameter, 4-8 long; not constricted at the cross walls, which are granular; cell contents granular, especially at the cross walls. Tychoplanktonic; on submerged vegetation. Wis. Phormidium lucidum (C. A. Ag.) Kuetzing 1843, p. 194 Filaments forming thick, firm mats which are dark green above but colorless within. Trichomes somewhat parallel, either curved or (at least at the ends) straight, and slightly tapering, sometimes ending in a point but with the apical cell capitate; calyptra broadly rounded; sheath diffuent and not colored by chlor-zinc-iodide reagent. Cells very short, 7-8» in diameter, 2-2.5p long; slightly constricted at the cross walls, which are granular. Mich. Phormidium minnesotense (Tilden) Drouet 1942, p. 136 Filaments forming a blue-green, thin expanse; individual sheaths indistinct, confluent with the mucilage of the plant mass; trichomes straight or slightly curved, parallel or somewhat entangled, not tapering at the distal end; apical cell broadly rounded, not capitate, and without a calyptra; cells short-cylindric, 2.5p in diameter, 2-4 long, constricted at the cross walls. Tychoplankter. Wis. Phormidium mucicola Naumann & Huber-Pestalozzi in Huber-Pestalozzi & Naumann 1929, pp. 67, 68 Pl. 111, Figs. 4,5 Filaments short, clustered or scattered in the mucilage of other blue-green algae (Microcystis). Sheaths thin, inconspicuous, difflu- ent. Trichomes parallel or scattered; up to 50, long; not tapering at the apices, which are broadly rounded or conical. Cells quadrate to short-cylindric, 1.3-2» in diameter, 1.8-3p long; constricted at the cross walls, often separated from one another; cell contents pale blue-green. This species is a frequent inhabiter of colonies of Microcystis aeruginosa, in which there may be far fewer Microcystis cells than Phormidium filaments. Rather common in hard water; euplanktonic. Mich., Wis. Phormidium Retzii (C. A. Ag.) Gomont 1892a, p. 175 PIM Hig.6 Filaments forming thin, dark blue-green skeins or tufts on sub- merged aquatics, or floating free; sheaths thin and inconspicuous, diffuent; trichomes straight, parallel, not tapering at the apices, or [ 495 ] very slightly so; apical cell truncate, with the outer membrane thickened; cells quadrate, or longer (sometimes shorter) than wide, 4.5-12u in diameter, 4.8» long, usually not constricted at the cross walls except in the distal end of the trichome; cell contents granular. On submerged aquatics or floating in small tufts in hard water lakes; forming thick, streaming tufts in flowing water; forming a membrane on casing of a spring. Mich., Wis. Phormidium Setchellianum Gomont 1892a, p: 156 Filaments forming a thin, weft-like, dark purple layer; sheaths thin and generally confluent with the mucilage of the plant mass; trichomes curved or straight, often hooked at the apex, which is not tapered, or but very slightly so; apical cell capitate with a coni- cal calyptra; cells 44.8 in diameter, 3-6» long, constricted at the cross walls; cell contents purplish. On muddy shores. Mich. Phormidium subfuscum Kuetzing 1848, p. 195 Pl. 107, Fig. 16 Filaments forming a widely expanded, thin and Jamellate plant mass, dark green (or olive) in color. Trichomes straight, agglutinated and more or less parallel, relatively short; straight at the apex and briefly tapered; sheath becoming diffluent with the mucilage of the plant mass. Apical cell capitate, with a broadly rounded calyp- tra. Cells 5.5—11p in diameter, 2—4y long, granular, not constricted at the cross walls. Cell contents sometimes granular and_ blue- green in color. On log near shoreline of lake, Mich. Phormidium tenue (Menegh.) Gomont 1892a, p. 169 PRAT, Figs 7 Filaments forming a blue-green, membranous expanse; sheaths diffuent, mucilaginous and indistinct; trichomes straight except at apices, where they are bent and attenuated; apical cell conical, smooth, neither capitate nor furnished with a calyptra; cells 1.2-8 in diameter, 2.5-5y long, constricted at the cross walls, which are not granulate; cell contents homogeneous. Common, forming thin films on submerged aquatics and inter- mingled with decaying vegetation in shallow water. Mich., Wis. Phormidium uncinatum (C. A. Ag.) Gomont 1890, p. 355 Pl. 107, Fig. 18 Filaments forming an expanded, thin but firm plant mass, either [ 496 ] floating or adherent to a substrate, dark green or brownish; tri- chomes straight or curved, briefly tapered at the apex, which is hooked or spiralled; sheaths sticky, distinct finally but becoming confluent with the mucilage of the plant mass; apical cell capitate, with a rotund or conical calyptra; cells not constricted, 6—9 in diameter, 2—6p long, granular at the cross walls; cell contents blue- green. On mud near stream, Mich. LYNGBYA Agardh 1824, p. XXV Filamentous, composed of a uniseriate, unbranched trichome of cells inclosed by a non-gelatinous, more or less firm sheath; plank- tonic and solitary, or aggregated, forming entangled masses on substrates or intermingled among other algae; some species spirally coiled; trichomes mostly cylindrical throughout and tapering very slightly, if at all, toward the apices, which are usually not capitate. In favorable habitats some of the planktonic species may become superabundant, but unlike Aphanizomenon flos-aquae and Micro- cystis aeruginosa, the plants remain distributed throughout the water and do not form sticky masses and floating scums; hence they seldom figure in water bloom disturbances. Key to the Species 1. Filaments spirally coiled or twisted, sometimes entwinedsabout other “algae. 5st t = eee ee ee a ee 2 1. Filaments straight, curved, or entangled, buiamotadelinitely coiled)... 525 2550s ee = 2. Filaments wound about and creeping over Otnenmlamentous algae. 2 Se 2 Sa ee L. epiphytica 2: Filaments not entwined about other algae 3 3. Trichomes very loosely spiralled, or merely Wwaviye(Obtenystraip hips: 2 et L. spirulinoides 3.) brichomes closely coiled and: twisted == 52 4 4, Trichomes irregularly twisted and coiled _____________-_____- L. Lagerheimia 4°vtrichomes recularly*spiralled&s 222233205 ye L. contorta Sea bilaments: 0-59 ini diametcrees oS 6 i, liibmaeaes Teas doch OO) tim Gleronelyere 8 6. Filaments euplanktonic, 20-24, in diameter; sheath Oio—40 thick: solitary) ss ee Se L. Birgei 6. Filaments tychoplanktonic, intermingled with Otheralaae: ox tormming a plant mass a 7. Filaments 44—58u in diameter; sheaths up to 5u thick; intermingled with other algae__________________-_-------------- L. latissima 7. Filaments 8—24—(28)u in diameter; sheaths thinner; usually forming) entangled plant) masses= == == a L. aestuarii S-ePlants cuplanktonic amd solitary 9 8. Plants epiphytic, adherent and forming plant masses, or entangled among other algae, tychoplanktonic__.___. 12 [ 497 ] A FGil armemtSpelale NG pepsin Gli arn © ee eee 10 Hilamemntssorria lle retook oP eae ee I Se Mal . Trichomes 11-13. in diameter, usually with, pseudovacuoles =)" 2) Ss a L. Hieronymusii . Trichomes 14—16u in diameter, without pseudovacuoles L. spirulinoides ; Plant mass*purpleyor purple-red= 2 ee L. purpurea Plants; solitany, iblue-gteen= == == see eee L. limnetica //Plantamass) purplish or purple-ted= = ee L. purpurea ‘yPlantmass (eray- 01 bltie-Sreem se eee ee 13 . Filaments small, 14—(rarely 5) in diameter________-__----------------------- 14 ) Hilaments) 5-202 nuedianicter = ee 16 . Plants forming a layer of much entangled filaments, (‘See also EZ: Diguert below) = === L. versicolor . Plants not forming a definite mass or layer; solitary or gregarious; epiphytic ________________ 15 . Filaments 1.2—2u in diameter, lying prostrate along the host plant for much of their length and then curved away to form a free apical portion; cells usually quadrate or shorter than wide __ L. Nordgaardii . Filaments 2-3.2u in diameter, arising directly from the host plant, with little of their length prostrate; cells usually longer than wide; filaments sometimes forming a plant mass, usually on Rhizoclonium or Cladophora, or other filamentous algae which do not have a mucilaginous outer wall layer L. Diguetii Filaments sl0-20u inidiameter =e ee ee eee ff Bilamentseo=) Owsine aiameten= oss eee owe en ee eee 18 . Filaments mostly straight; apical cell with a thickened outer | membrane; trichomes 11-17 in diameter ___--____-_----.----------- L. major . Filaments much entangled; apical cell without a thickened outer membrane; trichomes variable, (8)—10-20—(24) in diameter _ L. aestuarii . Filaments lying parallel, forming tufts —.__-____________ L. Taylorii . Filaments not lying parallel and not forming Gefmitestutts se 19 _ Trichomes small, 2.8-3.4u in diameter; filaments up to 5u wide; sheaths thick (2u); cells usually distinctly longer than wide —. L. versicolor . Trichomes larger; cells shorter, 1.7—3.34 long. a ee 20 . Filaments 6—10u in diameter; apical cell rotund: sheaths, thick 00) = lees he L. Martensiana . Filaments 4—6u in diameter; apical cell conical, usually capitate, with a thickened outer membrane__.....---------------------- Ih aerugineo-caerulea Lyngbya aerugineo-caerulea (Kuetz.) Gomont 1892a, p. 146 Pl Fries; 10pm Plants aggregated, forming masses of curved and loosely entangled filaments among other algae, or expansions on submerged substrates (solitary filaments frequently found scattered among other plants); filaments (4)-6-(7.5)» in diameter; trichomes 4-7» in diameter; cells varying in length from a little less to longer than the width, 2.7-7.8» long, not at all or but very little constricted at the cross walls; apices of trichomes straight, with cone-shaped or slightly capitate terminal cells. Sheaths firm, thin, sometimes with regularly [ 498 ] spaced bands of roughenings; colorless; extending far beyond the apices of the trichomes. In a variety of lakes, both acid and hard water; in Sphagnum bogs. Mich., Wis. Lyngbya aestuarii ( Mert.) Liebmann 1841, p. 492 Pl. TUS igs Plants aggregated, entangled, forming extensive layers on sub- merged substrates, or upon moist earth and stones; sometimes be- coming free-floating. Filaments varying greatly in diameter, 10-26, wide. Trichomes 8-20-(28), in diameter, tapering a little at the apices, which vary in shape, conical, truncate, or somewhat capitate. Cells 2.5-5 in length, not constricted at the cross walls. Sheaths firm, becoming thickened, lamellose, and discolored with age. This species sometimes forms very thick, felt-like layers, yellow- gray or olive-green in color, the color ordinarily masked by accumu- lated silt and debris. On stones and moist earth. Mich., Wis. Lyngbya Birgei G. M. Smith 1916, p. 482 PL 1, Fig: 9 Plants solitary, planktonic, scattered among water bloom organ- isms; filaments straight, (18)-24-(25), in diameter, with many hormogonia when aged; sheaths thick and firm, not lamellated, ex- tending far beyond the apices of the trichomes, which are broadly rounded; trichome 20-24, in diameter, not constricted at the cross walls; cells very short and disciform, 3-7,» long. This species is frequently a prominent element in the composition of water blooms which develop in lakes with a pH of 7.4-9.0. It is almost invariably associated with Microcystis aeruginosa, Aphanizo- menon flos-aquae, Anabaena flos-aquae, Stephanodiscus spp. and Melosira spp. In fact, its association with these species in eutrophic waters is so constant that during the months of July and August, at least, the relative abundance of Lyngbya Birgei G. M. Smith can be used as an approximate index of alkalinity. Although abundant in hard water lakes it does not play an important role in the water bloom disturbances of which Aphanizomenon and Microcystis are capable, because of its failure to form clots and floating masses. Common in the euplankton of many hard and semi-hard water lakes. Mich., Wis. [ 499 ] Lyngbya contorta Lemmermann 1898, p. 202 Pl M2s Higa Plants solitary and planktonic, spirally twisted or coiled (rarely straight); trichomes not tapering at their apices and withaut con- strictions at the cross walls; cells 1.5-21 in diameter, 3.5-5.6y long; sheaths thin but firm. This plant sometimes becomes dominant in the plankton of a hard water lake and so abundant as to color the water a brownish- green or a rusty-gray. In some small Iowa lakes it has been found in almost pure growth with scarcely any other phytoplanktonic spe- cies present. The dispersed habit of the plant and its failure to agglutinate account for its inability to produce the unbalanced con- ditions produced by other blue-green plankters. Eu- and tychoplanktonic. Wis. Lyngbya Diguetii Gomont in Hariot 1895, p. 169 Pl. 112, Fig. 8 Plants solitary or entangled, sometimes forming bundles, fre- quently adhering to and growing out from filamentous algae which have non-mucilaginous walls; filaments up to 3.24 in diameter, sheaths thin; trichomes 2.5-3n in diameter, cells 1.5-3.54 long; apical cell convex, smooth. This is a very common species in hard water habitats and is in- variably found associated with Cladophora and Rhizoclonium. It is similar in some characters and in habitat to Lyngbya epiphytica Wille (Nyt Mag. f. Natur., 1913, p. 25), a synonym of L. Nord- gaardii Wille, but in our region is slightly larger than that species. Mich., Wis. Lyngbya epiphytica Hieronymus in Engler & Prantl 1900, p. 67 Pl. 112, Figs. 2,3 Plants epiphytic, entangled and spirally twisted about other filamentous algae to which they are adjoined throughout their en- tire length; filaments 1.5-2.5y in diameter; trichomes without con- strictions at the cross walls; cells 1.2-2u in diameter, 1-2» long; apical cell convex, not capitate; sheath thin and close. This species is not to be confused with L. epiphytica Wille, which is synonymous, apparently, with L. Nordgaardii Wille (Frémy, Soc. Arch. et Hist. Nat. Manche, 47, p. 44, 1936). On filamentous algae. Tychoplankter. Wis. [ 500 ] Lyngbya Hieronymusii Lemmermann 1905, p. 146 Pl, 112,' Fig. 4 Plants solitary, scattered among other algae or in littoral plankton. Trichomes straight and not tapering at the apices, which are broadly convex; 11-13 in diameter. Cells 45-15 as long as wide (2.7—-4u long); usually with pseudovacuoles; not constricted at the cross walls, which are granular. Sheath rather thick, but homogeneous, not lamellose. Filaments (12)-14-19, wide. This species should be compared with L. major Menegh. and L. Birgei G. M. Smith. From the former it differs in the convex, non- tapering apices, the homogeneous sheaths, and its failure to form agglutinated masses. From the latter species it differs in size and in its possession of granular cross walls. Tychoplankter. Mich., Wis. Lyngbya Lagerheimia (Moebius ) Gomont 1890, p. 354 Pl. 112, Figs. 5, 6 Plants solitary or somewhat entangled, bent and twisted, some- times spiral; trichomes not at all or but very slightly tapering toward the apices, which are broadly conical or convex; cells 2.2—-3y in diameter, 1.5-2.8. long; cell contents coarsely granular; sheaths thin; filaments 2-2.5, wide. Among other algae in shallow water of lakes and in roadside ponds. Mich., Wis. Lyngbya latissima Prescott 1944, p. 372 PI. 112, Fig. 9 Plants solitary, planktonic, entangled among other floating algae; trichomes straight, not tapering toward the apices; cells disc-like, with contents finely and evenly granular (sometimes with coarse granules in old plants), 37-40.7 in diameter, 3.7-7.4y long; sheaths thick, 3.7-5» wide, lamellated, with outer layers wrinkled and roughened in age; filaments 44-58, in diameter. This species, found in but two habitats, may be a planktonic and unbranched expression of Plectonema Wollei. The plants described by Prescott (1944, p. 372) are about the same diameter as this large species of Plectonema, and they have some of the same sheath characteristics. The filaments are entirely unbranched and solitary, however, whereas Plectonema Wollei is branched (although infre- quently) and occurs in woolly mats. Lyngbya latissima should be com- pared also with Oscillatoria princeps when the latter is in a hor- mogonous condition and inclosed by a sheath. The sheath is not thick and lamellated as in our plant, nor are the trichomes so long. [ 501 | L. gigantea Lewis, Zirkle, and Patrick (1933), referred by Drouet (1938) to Oscillatoria princeps, differs in having thin smooth sheaths characteristic of the hormogonial phase of the latter. Our specimens are not at all tapering at the apices, and the contents of the cells are granular. Lyngbya Hummellii Borge (1934), a large species, differs from L. latissima in its smaller size (874, maximum width) and in the longer cells (6-11). Also the sheath of Borge’s species is thinner and apparently not lamellated as in our specimens. Euplanktonic and tychoplanktonic. Wis. Lyngbya limnetica Lemmermann 1898d, p. 154 Pd igo, Plants straight, solitary, planktonic; trichomes 1-2-(2.5)y in diameter, not tapering at the apices; cells 6-12 long, not con- stricted at the cross walls; cell contents coarsely granular; sheaths thin and colorless; filaments 2—2.2u wide. Euplankter. Wis. Lyngbya major Meneghini 1837, p. 12 P1112, Fig. 10 Plants solitary among other algae, or somewhat gregarious, but not forming expansions or plant masses; filaments straight; tri- chomes not or but very slightly tapering to the apices, which are indistinctly capitate in older plants, 11-17 in diameter; cells 14- 1/4 as long as wide, (2)—3.5—4u in length, not constricted at the cross walls, which are definitely granulose; cell contents homogen- eously granular; sheaths thick (3-3.7,), firm, and usually lamellated, becoming roughened in age; filament 22-26, in diameter. Caught about Utricularia and other vegetation; widely distributed in a variety of lakes, mostly hard water; tychoplanktonic. Mich., Wis. Lyngbya Martensiana Meneghini 1837, p. 23 Pl. 112, Fig. 11 Plants much entangled and interwoven to form an expanded, dark blue-green mass; trichomes 6—10—(12)y in diameter, not tapering toward the apices, which are broadly convex; cells about 1/4 as long as wide, 2.5—2.84 long, not constricted at the cross walls, contents homogeneous except for 1 or 2 conspicuous gran- ules at the cross walls; sheaths firm, moderately thick (1.5—2,); filaments mostly 6—10» (up to 14.) in diameter. This plant is assigned here on the basis of size, lack of constric- tions at the cross walls, and the tendency to form plant masses. It [ 502 } is similar to L. putealis Montagne, but that species has trichomes constricted at the cross walls. Our specimens should be compared also with L. major. Rare; in tychoplankton. Mich., Wis. Lyngbya Nordgaardii Wille 1918, p. 32 [Lyngbya epiphytica Wille 1913, p. 25] Pl. 118, Figs. 1, 2 Plants solitary or forming minute patches on the walls of larger filamentous algae (Oedogonium, Rhizoclonium), curved and vermi- form, sometimes recurved from a basal attachment; trichomes gray- green, not tapering at the apices, 1.2-2 in diameter, about as long as wide or a little shorter; sheaths very thin and transparent. On Drepanocladus from a depth of 35 feet; on filamentous algae, and in tychoplankton. Wis. Lyngbya purpurea (Hook. & Harvey ) Gomont 1892, p. 49 Plant mass highly mucilaginous, purplish red; trichomes some- times scattered among other algae, curved and flexuous, not con- stricted at the cross walls, 1.4-1.8. in diameter; sheath thin and transparent, not stained blue by chlor-zinc-iodide; cells quadrate. Mich. Lyngbya spirulinoides Gomont 1890, p. 355; 1892a, p. 146 Pld), aig. 1 Plant mass planktonic, olive-green; filaments entangled, loosely spiralled through most of their length (or all of it), rarely straight; cells light blue-green, with homogeneous or slightly granular con- tents; sheaths thin and homogeneous, sticky and colorless; trichomes 14-16, in diameter, not constricted at the cross walls nor tapering toward the apices; apical cell broadly rounded, not capitate, and without a calyptra; cells 3.46.8» long. Tychoplankter. Wis. Lyngbya Taylorii Drouet & Strickland in Strickland 1940, p. 631 Pl. 118, Fig. 3 Plants forming tufts of parallel but flexuous filaments on sub- merged substrates, or floating free. Trichomes not tapering toward the apices; very little or not at all constricted at the cross walls; 4-7, in diameter. Terminal cell broadly convex. Cells quadrate, about as long as wide or a little shorter; cell contents granular. Sheaths thin and colorless; filaments long, 6-9» in diameter. Forming a bright blue-green film on mud; tychoplankter. Wis. [ 503 ] Lyngbya versicolor (Wartmann) Gomont 1892a, p. 147 Pl. 113, Fig. 4 Plants forming a mucous expansion on submerged objects, be- coming detached and floating; filaments much entangled; trichomes not tapering toward the apices and not constricted at the cross walls, which are not granular; cells 2.8-3.44 in diameter; filaments 3-3.8-(5) in diameter; sheaths thick (up to 2), mucous. Forming compact films on submerged logs; tychoplankter. Mich., Wis. SYMPLOCA Kuetzing 1843, p. 201 Unbranched sheathed filaments, united in branching bundles or fascicles which are erect or growing out and away from the sub- strate to which they are attached (rarely free-floating); trichomes uniseriate and straight, tapering distally but very slightly; apical cell conical or broadly rounded, sometimes with a thickened outer membrane; sheaths firm and close, or confluent in the median portion of the filament only, thus producing the effect of false branching; cells quadrate or cylindric, slightly, if at all, constricted at the cross walls. Symploca muscorum (C. A. Ag.) Gomont 1890, p. 354 Pl. 113, Fig. 7 Filaments forming brownish-green, erect or procumbent tufts or fascicles (often producing Phormidium-like expansions); tri- chomes straight or wavy, parallel; cells quadrate to cylindrical, not constricted at the cross walls, 5-8. in diameter, 5-11, long; cell contents densely granular; apical cell broadly rounded or obtuse- conical; sheaths firm, thin, close. Along sides of ditches and in Sphagnum bogs; rare in our collec- tions, although a widely distributed and common species. Mich., Wis. HYDROCOLEUM Kuetzing 18438, p. 196 Trichomes few to several in relatively wide, lamellate, and color- less sheaths, which are in part close and definite, becoming diffluent, the sheaths sometimes branching; forming a cushion-like expanse (sometimes lime-encrusted ); individual trichomes tapering slightly at the apices, the terminal cell usually capitate and sometimes with a calyptra; cells quadrate or shorter than wide. Hydrocoleum oligotrichum A. Braun in Rabenhorst 1865, p. 294 Plant mass cushion-like, lime-encrusted, and brownish in color; trichomes clustered in bundles, 2-6 within a lamellate sheath, [ 504 J golden-brown in color, tapering toward the apex, which is capitate; cells 6-8» in diameter, 3-9, long. In small pools on rock cliffs, Pictured Rocks, Michigan. MICROCOLEUS Desmaziéres 1823, p.7 Plant mass consisting of many parallel trichomes inclosed by a wide, gelatinous, homogeneous and sticky sheath; trichomes with basal-distal differentiation, tapering anteriorly to conical or capitate apices, closely entwined, sliding upon one another in and out of the sheath; cells quadrate or elongate-cylindric; contents granular but without pseudovacuoles; cross walls sometimes granular; plants mostly on moist soil, sometimes submerged on old wood in a gela- tinous mixture of miscellaneous blue-green algae. This genus should be compared with Schizothrix, which has firm colored sheaths, often forms erect tufts or fascicles of filaments, and is seldom aquatic. Key to the Species i PAnical cell capitate ete Se it eles ela i M. vaginatus i Apical cell. nok-capitate <7 A. a aS 2 2. Trichomes 4—5u in diameter, constricted Sistine .CrOss Wallssw AM UAliC ee oe en ee M. lacustris 2. Trichomes 5—7u in diameter, not constricted at the cross walls; plants teuallysonymoistisoll+ = #2 ee ee M. paludosus Microcoleus lacustris (Rab. ) Farlow in Farlow, Anderson, & Eaton 1877, Algae Amer. Bor. Exsic., No. 227 Pl. 113, Fig. 6 Aquatic; forming dark blue-green patches on submerged wood or on bottom. Sheaths colorless, confluent with the sheaths of other filaments, thin and evanescent at the ends; not stained by chlor-zinc- iodide reagent. Trichomes with bluntly tapering apical cells, not capitate; 4-5, in diameter. Cells distinctly cylindrical, constricted at the cross walls; 8-14, long; contents finely granular, blue-green. Among other filamentous blue-green algae in tychoplankton and adhering to submerged substrates. Mich., Wis. Microcoleus paludosus (Kuetz.) Gomont 1892, p. 358 Pl. 113, Fig. 5 Filaments either solitary among other algae or entangled to form dark green, thready masses; sheaths either closed and pointed (some- times forked) or open; sheaths sticky but not especially confluent, not colored by chlor-zinc-iodide reagent; trichomes compactly en- twined, tapering to blunt, conical apices, which are not capitate; [ 505 J cells 5-7 in diameter, 7-13-(14) long, not constricted or granular at the cross walls; cell contents bright blue-green. On moist soil at margins of lakes; tychoplanktonic. Mich., Wis. Microcoleus vaginatus (Vauch.) Gomont 1890, p. 353 Pl. 131, Fig. 2 Plants solitary or, more often, forming dark green and shiny hori- zontal layers; twisted and branched. Sheath colorless and either cylindrical throughout or irregularly undulate and wrinkled; not stained by chlor-zinc-iodide reagent; agglutinated and either open at the end or closed and diffluent. Trichomes numerous within the sheath; not constricted at the cross walls, which are often granular; tapering slightly and briefly at the apex, which is straight. Apical cell capitate, with a calyptra. Cells 3.5-7p in diameter, 14-2 times as long as wide. Mich. SCHIZOTHRIX Kuetzing 1843, p. 230 Plant mass consisting of several to many trichomes inclosed by a copious sheath of mucilage, which is usually firm and not sticky, the sheath colorless or yellowed, especially in age, frequently forked towards the ends with but a single trichome in the ultimate divisions; filaments either single, in fascicled tufts, or in an expanded layer; trichomes twisted and intertwined, cylindrical throughout but with the apical cell tapering to a blunt or sharp point; cells cylindrical, or shorter than wide, sometimes constricted at the cross walls. This genus should be compared with some species of Phormidium in which the sheaths are agglutinated and diffluent. Key to the Species isaSheathsy colored ese sts Pes tetg tn ws oly ek ee A 8 eee 2 1 $Sheathsacolorlessrt+lti nd et eels Pd ray Ante i ae ee 3 2. Trichomes 2.8—8u in diameter, not tapering at the apices, the end bluntly rounded_______________________----- S. fuscescens 2. Trichomes 6-13» in diameter, tapering slightly toward the apices; tne end\ canically rounded = 2 S. Muelleri 3. Filaments compactly agglutinated to form erect tufts_____________. S. Friesii 3. Pilaments notpapelutinated: to stom erect tuikts =e ee ee 4 4, Filaments branching but very little, ainited: toform'-horizontalilayers=— >!) Se eee S. lardacea 4. Filaments forming cushion-like masses, or penicillate, streaming ytuits= 2S eS SS 5 5. irichomes:>—Ullpeimydiameter sash Jeeeo e | istallyiby, arsingleycell (ne ee A. limnetica . Gonidia spheroidal or broadly ovate, separated from the lieteracyst by 2 or more cells= A. planctonica . Gonidia short-cylindric, not more than twice the diameter in length, hexagonal in optical cross section. A. macrospora . Gonidia usually more than twice the diameter in length, round in optical cross section _—--------—---—-----—----_~--_------ Wa [ 511 ] a(GOMIGTaiMaSeTICS = = sd et ae Ee ee ee ee A. Felisii 17 bie, Gonidiay solitary 3) <2. 8. 15s See eS ee ee eee ieee ke, eee 18 18. Vegetative cells 4u in diameter, 4—-6u long; gonidia slender, 6u in diameter and up to 56—(70)w long................ A. Augstumalis var. marchica 18. Vegetative cells 4—6u in diameter; gonidia larger, (fc =) Syrah baWECo bE 0cVel (=) pee meee eet te NT oe AS ie ee ee 19 19. Vegetative cells 4—6u in diameter; gonidia more than twice the diameter ofthe vegetative; cells) 2 aa ee ee A. Levanderi 19. Vegetative cells 5-6u in diameter; gonidia less than twice the diameter ofthe; vepetative Cellsiss sae se esneeenemnsanaemne ene See A. affinis 20. Gonidia developing adjacent to the heterocysts —-__.._--____________-__=_ 21 20. Gonidia developing remotely from the heterocysts, scattered 25 21. Vegetative cells globose or barrel-shaped ...-- De, 21s) Vegetative cellsycyling tical 26 roasts tae A. subcylindrica Zon Vegetative cells 4=—Oye in Cidmieter mee st mise eke ee, one eee 23 220) Vegetative cells (lar genie ata teen) oo Wes Lireeenl pein used sek eens 24 23. Gonidia cylindrical, with lateral margins parallel ___________ A. oscillarioides 23. Gonidia elongate-ovate, with lateral margins convex... A. torulosa 24. Vegetative cells 7.5-9u in diameter; gonidia UL BSG (Mey Nn Soy Ole A. lapponica 24. Vegetative cells 12u in diameter; gonidia 15—20u in diameter. A. Bornetiana Zo. Vegetativercells cylindrical +2 432 he Se ee ee 26 25. Vegetative cells ovate, barrel-shaped, or truncate-globose —..._____ 27 26. Gonidia usually in series, 10-12y in diameter, with a smooth outer membrane; vegetative cells 6-74 in diameter_._...-_____-__________. A. Felisii 26. Gonidia 1 or 2 together, 3.7-4-(7)u in diameter, with a rough outer membrane; vegetative cells 3-4u in diameter —_______ A. verrucosa . Trichomes lying somewhat parallel in a thin mucilaginous layer, usually extending over the surface of large filamentous algae or stems of aquatic plants; heterocysts round, 4—6u in diameter A. inaequalis . Trichomes not parallel; irregularly entangled or solitary ‘among jother algad = 20 Se 28 * Heterocysts) spherical 2. 0 ee ae ee A. affinis » Heteroeysts elongate-ovate or ellipsoid! 2. 29 » (Gonidia,in*series, OVvate or subglobose -.....2 22. er 30 . Gonidia 1 or 2 together, elongate to subcylindric ______-___ A. aequalis » Gonidia barrel-shaped, /.5—14p longs. A. variabilis . Gonidia oblong, often with retuse margins __________________________-- *A. catenula Anabaena aequalis Borge 1907, p. 65 Pl. 115, Figs. 1, 2 Trichomes straight, forming a small plant mass, or scattered among other algae; cells somewhat quadrate or barrel-shaped, (4.5)-5.5-7.5u in diameter, 7.6-8.5y long; heterocysts ovate to sub- cylindric, (5.5)-8. in diameter, (10)-13-(15.2)» long; gonidia cylindrical, remote from the heterocysts, the wall smooth and color- less, 5-7.6u in diameter, (21)-385-41-( 49.4), long. Tychoplanktonic; intermingled with other algae in shallow water in Sphagnum bogs. Wis. [512 } Anabaena affinis Lemmermann 1898a, p. 261 Pl. 115, Figs. 10, 14, 15 Trichomes straight or flexuous, solitary and free-floating, either planktonic or intermingled with other algae in the littoral flora, inclosed in a thin, wide, mucilaginous sheath (often indistinct); cells spherical to spheroidal with either homogeneous contents or with pseudovacuoles, especially the latter when plants are solitary in the plankton, 5-6-(7) in diameter; heterocysts spherical, slightly larger than the vegetative cells, 7.5-10, in diameter; gonidia usually short-cylindric, sometimes broadly ovate and ‘truncately rounded at the poles, scattered, solitary, 9.5—12y in diameter, 17—24—(26)p long. Rare to common in euplankton and tychoplankton of several lakes. Mich., Wis. Anabaena Augstumalis Schmidle 1899a, p. 174 Trichomes twisted and flexuous, free-floating, solitary; cells barrel- shaped or somewhat cylindric, 4—5p in diameter, 5-6, long; hetero- cysts cylindrical, slightly greater (64) in diameter than the vegeta- tive cells; gonidia narrowly cylindric, 6. in diameter, 30-50-(56) » long, adjacent to the heterocysts. This species should be compared with A. circinalis, also a plankter. Euplankter. Wis. Anabaena Augstumalis var. Marchica Lemmermann 1905, p. 147 Pl. 115, Fig. 11 Trichomes flexuous (not circinate), planktonic; cells spherical to cylindric with many conspicuous pseudovacuoles, 5-7 in diameter, 5-9.5u long; gonidia cylindrical, 9.5-12» in diameter, 40-70» long, remote from the heterocysts. In the plankton of several hard water lakes. Mich., Wis. Anabaena Azollae Strasburger 1884, p. 352 Pl. 115, Figs. 12, 13 Trichomes straight or coiled, often in small clusters but more frequently solitary, inhabiting the tissues of Azolla; cells subglobose to ellipsoid, the contents granular, 4-5y in diameter, 6-8-(9.5) uw long; heterocysts ovate, 6-9.5. in diameter, 9-10-(11.5)» long; gonidia not known. The lack of gonidia in these plants makes their identification questionable. It is possible that they are only a sterile condition of a free-living species called by another name. In the tissues of Azolla; shallow water and sloughs. Wis. [ 518 ] Anabaena Bornetiana Collins 1896, p. 120 Pl. 115, Figs. 8, 9 Trichomes straight, planktonic and solitary; cells spherical or compressed globose, contents densely granular or homogeneous, 11-12 in diameter; heterocysts nearly spherical, 10-12-(14), in diameter, 12-14-(20) long; gonidia cylindrical, adjacent to the heterocysts (often one on either side) or scattered, (12.8 )—14—(20) in diameter, (50 )—66-90, long. Plankter; in lakes. Wis. Anabaena circinalis Rabenhorst 1852, p. 209 BIG Sigs 2 Trichomes planktonic, flexuous and contorted; solitary or entangled to form floating clots which are easily visible to the unaided eye. Cells spherical or depressed-globose from contact; 8-12-(14), in diameter. Heterocysts spherical or compressed, 8-10» in diameter. Gonidia remote from the heterocysts, rarely adjacent; cylindric, straight or curved; (14)-16-18, in diameter, 22-30-(32), long. This species is very common and widely distributed. It is often found associated with A. spiroides in the plankton of hard water lakes. These two species, together with Microcystis aeruginosa and Gloeotrichia echinulata, are conspicuous components of water blooms during late summer periods. Anabaena circinalis may be differentiated from A. spiroides by the shape of the spore when in the reproductive condition, by the lack of regularity in the twisting of the trichome, and by the size of the cells in the vegetative state. Mich., Wis. Anabaena circinalis var. macrospora ( Wittr.) DeToni 1907, p. 445 Pl. 116, Figs. 5,6; Pl. 120, Fig. 1 A variety with smaller vegetative cells and narrower, more elon- gate gonidia. Cells 7-8 in diameter; heterocysts 7.5-10, in diameter; gonidia 9-10.5y in diameter, 28-42, long. Euplankter. Wis. Anabaena Felisii (Menegh.) Bornet & Flahault 1888, p. 232 Pl. 116, Figs. 3, 4 Trichomes straight; solitary or in small clusters. Cells short- cylindric, 6-7 in diameter, 7-llp long. Heterocysts ovate to sub- cylindric, 7» in diameter, 12-14» long. Gonidia scattered; solitary [514 ] or in short series; remote from the heterocysts; 10-12-(14), in diameter and up to 70, long. This species should be compared with A. oscillarioides, from which it differs in having spores remote from the heterocysts, which are subcylindric rather than round. The cells in A. Felisii are cylin- drical, whereas those of A. oscillarioides are barrel-shaped. Tychoplankter. Wis. Anabaena flos-aquae (Lyngb.) De Brébisson in De Brébisson & Godey 1836, p. 36 [A. Lemmermannii P. Richter] PING: Fig. 7 Trichomes planktonic; very flexuous and contorted, sometimes coiled in an irregular spiral fashion; either solitary or entangled in a twisted mass. Cells spherical to subcylindric; (4)-5-6-(8), in diameter, 6-8—(12) » long; cell contents granular with conspicuous pseudovacuoles. Heterocysts globose or somewhat depressed at the poles; 7-9» in diameter, 6-10, long. Gonidia cylindrical or sausage- shaped; solitary, or sometimes in a series, crowded near the center of a tangle of filaments; usually adjacent to the heterocysts; (6)-8- 12-(13), in diameter, (20)-—24-30-(50)» long. Common in the plankton of hard and semi-hard water lakes; sometimes producing conspicuous water bloom growths during the warm summer months, often in association with Microcystis aeru- ginosa and Gloeotrichia echinulata. Mich., Wis. Anabaena flos-aquae var. Treleasei Bornet & Flahault 1888, p. 230 [A. Mendotae Trelease 1889, p. 123] Pl. 120, Fig. 2 A variety differing from the typical by the somewhat smaller size of the vegetative cells and by the more slender gonidia; vegetative cells 41 in diameter. Heterocysts 5 in diameter, 10» long. Gonidia 6. in diameter, 40, long. Forming dense water blooms. Wis. Anabaena helicoidea Bernard 1908, p. 52 Pl. 116, Fig. 8 Trichomes free-floating; solitary or entangled in a group; spirally twisted throughout their length. Cells ovate or somewhat barrel- shaped, with large granules of food reserve, 3.5-3.8. in diameter, 4-5 long. Heterocysts globose, 5-6» in diameter, 6 long. Gonidia small, cylindrical, 54 in diameter, 17» long. This species is quite similar to A. flos-aquae but is separated pri- [ 515 ] marily on the form of the plant, which is a loose spiral, not a tangled knot. It also should be compared with A. circinalis which has gonidia of quite different shape, relatively longer and larger. Euplankter. Wis. Anabaena inaequalis (Kuetz.) Bornet & Flahault 1888, p. 231 [A. laxa (Rab.) Braun ex Bornet & Flahault 1888, p. 120] Pl. 116, Figs. 9, 10 Trichomes straight or slightly twisted; lying parallel and entwined and inclosed by a definite sticky sheath, 7.4-8. wide; forming gelatinous strands, entangled among other algae and adherent (sometimes floating free). Cells short barrel-shaped or truncate- globose, 3.7-4.2-(5) in diameter. Heterocysts globose or ovate, 4-6» in diameter, 7.24 long. Gonidia cylindrical, scattered, with wall often golden-brown when mature; 6-8» in diameter, 15—-16— (17) long. Among other algae and floating free in marginal waters. Mich., Wis. Anabaena lapponica Borge 1913a, p. 101 PL. 116 Fig. 11 Trichomes straight, somewhat entangled; cells globose, 7.4-9.2u in diameter; heterocysts globose, 7.4-10 in diameter; gonidia cylin- drical, (11.5)-13-14-(17) in diameter, 40.7-63—( 85) » long, develo- ping on one or both sides of the heterocysts. Type specimens of this plant have not been seen for confirmation, but our material agrees with Borge’s description. The spherical shape of the vegetative cells and heterocysts separate this species from A. oscillarioides, which has barrel-shaped or elongate-ovate vegetative cells and heterocysts. Tychoplanktonic in lakes; in roadside ditches. Wis. Anabaena Levanderi Lemmermann 1906b, p. 536 PI117, Figs. 1,2 Trichomes planktonic, solitary, straight or flexuous. Cells cylin- drical, 4-6 in diameter, 11-33, long; constricted at the cross walls, which are rounded; contents with pseudovacuoles. Heterocysts spherical to ellipsoid, 6.5-8, in diameter, 6.5-9.5-(14)» long. Gon- idia solitary, ellipsoid, 8—15y in diameter, 19—45y long. Euplankter. Wis. Anabaena limnetica G. M. Smith 1916, p. 481 PIAL, Fig..3 Trichomes planktonic, solitary, straight or flexuous, inclosed by [ 516 | a mucilaginous sheath. Vegetative cells spherical or compressed at the poles, (10)-12-14-(15) in diameter. Heterocysts globular, 10—14, in diameter. Gonidia broadly ovate, near to the heter- ocysts or scattered, 17-20 in diameter, 20-30, long. Euplankter. Mich., Wis. Anabaena macrospora Klebahn 1895, p. 269 Pl. 117, Figs. 4-6 Trichomes planktonic, straight or flexuous, solitary; cells globose or somewhat ellipsoid, 5-6.5. in diameter, (5)-6-8-(9), long; heterocysts spherical, about 6, in diameter; gonidia globose to ovate, angular in optical section, not adjoining heterocysts, 17—18.5u in diameter, 24—26, long. Plankter; in many hard and semi-hard water lakes. Wis. Anabaena macrospora var. robusta Lemmermann 1898d, p- 154 Pl. 7, Fig. 7 Trichomes planktonic and solitary. Cells globose or ellipsoid, 9.7-11 in diameter. Heterocysts globose, 11.54 in diameter, 11-12y long. Gonidia globose or ovate; scattered, or adjacent to the heter- ocysts; 13.2-15, in diameter, 27-28-(34) » long. Plankter; in several hard water lakes; often appearing in water bloom associations in late summer. Wis. Anabaena oscillarioides Bory 1822, p. 308 Pl. 117, Figs. 8-10 Filaments straight, or entangled in a thin gelatinous layer or soli- tary. Cells barrel-shaped or truncate-globose, 4—6u in diameter, 7.8-8 long. Heterocysts round or ovate; 6-8» in diameter, (6)— 9.2-(10) long. Gonidia cylindrical; developing on both sides of the heterocyst (rarely on one side only); 8-10-(15.2) in diameter, 20-40-(76) » long. Spores in our specimens are larger than those originally described for this species. Forming thin films on submerged aquatics, or subaerial in swampy places and along margins of lakes. Mich., Wis. Anabaena planctonica Brunnthaler 1903, p. 292 Pl. 118, Figs. 1-3 Trichomes solitary, free-floating, inclosed in a wide gelatinous sheath; cells barrel-shaped or spherical, 9-15» in diameter, 6.5-10 long, with pseudovacuoles; heterocysts spherical, with lateral ‘wings’ of mucilage, 9—l1p in diameter; gonidia ellipsoid, 10—14, in diam- eter, 15-30, long, near or remote from the heterocysts. Plankter; in lakes. Wis. [al] Anabaena Scheremetievi Elenkin 1909, p. 125 Pl. 117, Figs. 11, 12 Trichomes planktonic; mostly straight, sometimes flexuous with a gelatinous sheath. Cells spheroidal or barrel-shaped; with pseudo- vacuoles; 8.5-9-(11)» in diameter, 8-11-(12)» long. Heterocysts spherical, 8-10.8, in diameter. Gonidia spherical to ellipsoid, some- times angular in optical section, not adjacent to heterocysts, (18) —20—22.6» in diameter, 21—24u long. Euplankter. Wis. Anabaena spiroides Klebahn 1895, p. 268 Trichomes spiral, solitary, inclosed in a thin mucilaginous sheath. Cells spherical or compressed-spheroidal, 6.5—-8 in diameter. Hetero- cysts spherical, slightly smaller than the vegetative cells. Gonidia spherical, 14 in diameter; adjacent to the heterocysts. Typical form not reported from our region. Anabaena spiroides var. crassa Lemmermann 1898d, p. 155 Pl. 117, Fig. 13; Pl. 118, Figs. 4,5 Trichomes solitary, spirally twisted, planktonic. Cells spherical, 10-11.5y in diameter. Heterocysts subspherical, 10u in diameter, 12 long. Gonidia oblong; remote from the heterocysts; 19-20, in diam- eter, 25-30p long. Plankter; in many lakes; especially abundant in late summer, appearing in water blooms with A. circinalis and A. flos-aquae. Wis. Anabaena subcylindrica Borge 1921, p. 12 Pl. 118, Figs. 6-8 Trichomes straight; solitary or forming a thin layer; adherent on submerged aquatics and entangled among other algae. Cells short- cylindric, 44.5» in diameter, 5.5-8—(10) long. Heterocysts cylin- drical, 5-7.5-(10) in diameter, 15—(18) long. Gonidia cylindrical, adjacent to heterocysts, 7—8.5u in diameter, 54—57p long. Sphagnum bogs; tychoplanktonic in soft water lakes. Wis. Anabaena torulosa (Carm.) Lagerheim 1883, p. 47 Filaments somewhat straight or irregularly bent (not coiled); forming sparsely clustered flakes. Cells subspherical or barrel- shaped, 4.2-5 in diameter; the terminal cell conical. Heterocysts globular, 6 in diameter. Gonidia elongate-ovate to subcylindric, with smooth convex lateral walls; solitary or in a series, on either side of the heterocyst; 7-12 in diameter, 18-28, long. Mich. [ 518 ] Anabaena unispora Gardner 1927, p. 59 PI. 131, Fig.5 Filaments straight or slightly curved, mostly solitary. Cells rec- tangular, 2-4 times longer than wide; 4-5, in diameter, 11-20, long; slightly constricted at the cross walls. Heterocysts elongate-ovate or subcylindric, 6 in diameter, 11y long. Gonidia solitary; developing near the middle of the filament and close to the heterocyst; elongate- ovate, the margins subparallel or slightly convex; 11-15,» in diameter, 31-35, long. Mich. Anabaena variabilis Kuetzing 1843, p. 210 Pl. 118, Figs. 9, 10 Trichomes entangled in a gelatinous plant mass, on damp soil, or floating entangled among other algae. Cells compressed-globose, 3.7-4-(6.5) in diameter. Heterocysts globular or ovate; 5.5-5.8- (8) in diameter, 5.8-6.5, long. Gonidia ovate; in series; remote from the heterocysts; 6.8—9 in diameter, 7.5-8.2—(14)» long. In seeps and ditches. Mich., Wis. Anabaena verrucosa Boye-Petersen 1923, p. 299 PIS. Figs. 11512 Trichomes straight, parallel, with a wide gelatinous sheath; grow- ing on and adherent to other filamentous algae. Cells short-cylindric, 3.3-4n in diameter, 3.3-6-(8) long. Heterocysts cylindrical, 3.6, in diameter, 5h long. Gonidia cylindrical; remote from the hetero- cysts; 4~7p in diameter, (10.5)-12-(15) long. Tychoplankter. Wis. PAnabaena Viguieri Denis & Frémy 1923, p. 122 PI. 119, Figs. 1-3 Trichomes planktonic; straight. Cells barrel-shaped to short- cylindric; 77.8 in diameter, (4)-9-10u long; with pseudovacuoles. Heterocysts globose to subglobose; 7.6. in diameter and up to 9u long; smaller than the vegetative cells. Gonidia broadly ovate; 12-14-(15) in diameter, 17-18.5p long; solitary or in 2’s; not ad- jacent to the heterocyst. This interesting plant was found in but one collection made in our area. It agrees in most respects with the description of A. Viguieri, but the cells are slightly longer. Euplankter. Wis. [ 519 ] Anabaena wisconsinense Prescott 1944, p: 378 Pl. 115, Figs. 3-7; Pl. 119, Figs. 4-8 Trichomes planktonic; straight or slightly flexuous; solitary or (more often) aggregated in parallel fashion to form small, loose, flake-like bundles; without a sheath; not tapering at the apices. Cells quadrate to cylindrical; constricted at the cross walls; 3.64 in diameter, 3.6—10.8 long; with large pseudovacuoles. Heterocysts spherical or compressed-globose, 3.6—-4.24 in diameter; only 1 in each trichome, centrally located. Gonidia elliptic-ovate to broadly oval, 7.2-8 in diameter, 10-13 long; beginning their development as a series of 3 enlarged vegetative cells, of which usually only 1 matures, so that each trichome has but a single gonidium (if more than 1, the gonidia in pairs); remote from the heterocysts. This plant is remindful of Aphanizomenon flos-aquae. It should be compared with Anabaena aphanizomenoides Forti, from which it differs in its smaller size throughout, in the shape of the gonidia, and in the location of the gonidia (remote from, rather than adjacent to, the heterocysts ). Both euplanktonic and tychoplanktonic. Wis. ANABAENOPSIS (Wolosz.) Miller 1923, p. 125 Trichomes planktonic; short and coiled, with a heterocyst at either end. Cells elongate-ovoid to subcylindric. Akinetes intercalary, re- mote from the heterocysts. Anabaenopsis Elenkinii Miller 1923, p. 125 PI. 131, Fig..4 Trichomes composed of ellipsoid or elongate-ovoid cells which contain pseudovacuoles. Heterocysts spherical, 4.6-6.7» in diameter. Akinetes broadly ovoid, 8.3-10.5u in diameter, 9.3-12 long; some- times nearly spherical, 8.3-10.7, in diameter. Cells 4.6-5.7y in diameter. Cheboygan County, Michigan. NOSTOC Vaucher 1903, p. 203 Membranous or globular or irregularly lobed colony of tangled, uniseriate unbranched trichomes of globose and bead-like, barrel- shaped, or cylindrical cells, inclosed in copious, thick mucilage which (in many species) outwardly forms a firm integument, giving the colony a fixed and definite shape; individual sheaths of the trichome confluent with the colonial mucilage; trichomes without basal-distal differentiation, made up of vegetative cells, frequent [ 520 ] heterocysts and, when mature, gonidia which are either solitary or in series. This genus should be compared with Anabaena in which some species have trichomes similarly inclosed in a thick mucilage but for which there is no definite shape. The colonial mass in Anabaena is soft, spreading, and does not retain its shape when removed from the water. Key to the Species 1. Plants inhabiting the tissues of Ricciocarpus and ROtherwlivernwOnts = ee es eee See Saree N. sphaericum (See also N. punctiforme. ) i) Plants dree-living, aquatic, or subserial 2. 2 2. Colonies globular masses of microscopic size, attached or entangled among other algae_______________ N. paludosum DeRSOl@Hics (ot sinc hOSCODICUSIZG == mee oe ee 3 3. Colony a membranous expanse, usually Subacha N. muscorum (See also N. Linckia and N. commune.) 3. Colony globular, regular in shape or lumpy and warty; mostly aquatic 4 4, Trichomes inclosed in a thick, tough, wrinkled mucilage, at first globular and solid, later becoming hollow and irregularly tuber- cular; colonies olive-green or brownish; trichomes densely en- tangled at the periphery of the colonial mass. N. verrucosum 4, Trichomes not in leathery, hollow, tubercular Colonies = ee ee 5 5. Colonies spherical, planktonic, blue; Pe erynia a vGd IMIG LOR: = roe oh SS N. caeruleum 5. Colonies not definitely planktonic; not blue 6 6. Colonies with a firm outer membrane; definite in shape; usually globular —_______ SER Seen Gi ne Ain A ls SR a tt 7 6. Colonies without a firm outer membrane or integument; usually soft and amorphous, although retaining their shape when re- THOU LaCO Dy ava Ry ee eS ee eS eee 11 q. Plants! growmay on! moist Sol 9 fe blants) crowing nh) Water ee ee ee 8 8. Cells 4-5u in diameter; gonidia elliptic or spherical, 5-7y in diameter; colonies tuberculate or expanded irregularly N. sphaericum 8. Cells 4—6y in diameter; gonidia spherical, 104 in diameter; colonies firm, globular pellets,. sometimes several adhering together; Uisulllys Price AriOUS eee se oe N. pruniforme 9. Colonial mass membranaceous, expanded (although at first form- ing elopuinr wiaSses)- = ee N. commune OuColonialamassimotanembranacecous 10 10. Cells cylindrical; constricted at the end walls, which are truncate; gonidia ellipsoid to cylindric, 6-74 in diameter, 6—14u long N. ellipsosporum 10. Cells barrel-shaped, short; gonidia oval, niin ie Lens ir powON Gc Asso es see oe N. sphaericum 11. Trichomes densely entangled, filamentous arrangement not clearly discernible —______________----------- N. punctiforme 11. Trichomes not so densely entangled that the filamentous arrange- fHent is not easily discernible es 12 12. Plants terrestrial; individual sheaths apparent; cells rather large, 5—8u in diameter; gonidia 6—7u in diameter, 10-154 long _N. microscopicum 12. Plants aquatic; individual sheaths not apparent; vegetative cells averagine smaller thanvaboye = so) ss iens eee ee 13 13. Colonies when old forming irregularly expanded, gelatinous, free- floating masses; cells cylindrical, 3.5-44 in diameter; hetero- Gystsr@vaterOr ODO tees ee ee N. carneum 1oer@ells not acyuund ni call see nen Serene ee ee 14 14. Trichomes densely and compactly entangled; gonidia/@—7 41m) diameter, (Op long. eae a N. Linckia 14, drichomes not. densely, entangled 15 15. Cells of various shapes within the same trichome, globose to elon- gate and barrel-shaped; heterocysts globose or oblong, slightly larger\than'the vegetative cells. 3 N. spongiaeforme 15. Cells all spherical or compressed-globose; heterocysts globose, larger, up to twice the size of the vegetative cellsave Vos? N. comminutum Nostoc caeruleum Lyngbye 1819, p. 201 Pig) Bigs, LOo Colony spherical, planktonic, 5-10 mm. in diameter, appearing as bright, sky-blue globules dispersed through quiet water; colonial sheath firm and tough; trichomes densely entangled; cells sub- spherical or barrel-shaped, 5-7 in diameter; heterocysts frequent, subglobose or spherical, 8-104 in diameter; gonidia apparently never described. Rather uncommon in plankton of lakes with eutrophic character- istics. Mich., Wis. Nostoc carneum C., A. Agardh 1824, p. 22 Pl. 119, Fig. 9 (showing an atypical form ) Colony olive-green or blue-green, globular, becoming irregularly lobed in age and finally expanded soft to firm; trichomes twisted and entangled but not crowded. Cells subglobose to short-cylindric, sometimes twice as long as wide, 3-4 in diameter, 6-8p long; con- stricted at the cross walls. Heterocysts ovate, 6-7 in diameter, 8p long. Gonidia ovate to oblong, 6-7» in diameter, 8-10, long. On the bottom, and floating at the surface of quiet water; forming soft gelatinous expansions when old but retaining a firm tegument. Wis. Nostoc comminutum Kuetzing 1849-1869, Tab. Phyc., 2, p. 3 Pl. 119, Fig. 12 Colony an irregularly lobed and membranaceous mass, golden- brown in color, the investing mucilage soft but retaining a definite shape when removed from the water. Trichomes twisted or some- what entangled. Cells globose or compressed-globose; 3.7-4. in [ 522 ] diameter, 3-4, long; either adjoined or separated (in different parts of the colony). Heterocysts spherical, 6. in diameter. Gonidia not observed (unknown ?). Tychoplankter; also found on bottom in shallow water. Mich., Wis. Nostoc commune Vaucher 1903, p. 222 Pl V19 3 Biggs Plant at first a brown, globular, firm, gelatinous mass, later, especially when growing on moist soil, becoming expanded; lobed and clathrate; forming tough leathery layers of considerable extent (20 cm. wide). Trichomes closely entangled and intertwined, espe- cially compact in the outer, brown, layer, less so in the colorless, softer, inner region of the colony. Cells subglobose or barrel-shaped 4-6 in diameter, 7» long; constricted at the cross walls. Heterocysts frequent, spherical, 7-8.4» in diameter. Gonidia the same shape and about the same size as the vegetative cells. On the bottom and on submerged objects; collected from depth of 20 feet in soft water lakes; on damp soil at the margin of lakes and swamps. Mich., Wis. Nostoc ellipsosporum (Desmaz. ) Rabenhorst 1865, Vol. 2, p. 169 Plant mass reddish-brown, irregularly globular. Trichomes loosely entangled. Cells subcylindric to cylindric; 4p in diameter, 6-14p long; constricted at the cross walls, which are truncate; cell contents yellowish or olive. Heterocysts subglobose or oblong, 6-7» in diam- eter, 6-14, long. Gonidia ellipsoid or cylindric-oblong; 6-8 in diameter, 14-19, long; with smooth walls. On grass at margin of lakes; on clay banks. Mich. Nostoc Linckia (Roth) Bornet & Thuret 1880, p. 86 Pl. 119, Figs. 14-16 Colonies firm and globular when young, becoming irregularly expanded, clathrate, and membranous, soft in age; blue-green in color, becoming dirty green. Trichomes much entangled, twisted. Cells subglobose or barrel-shaped, 3—4.5p in diameter. Heterocysts subspherical to ovate, 6—7.54 in diameter. Gonidia subglobose; 6—7, in diameter, 7—8» long; with dark, smooth membrane. Among clots of filamentous algae in hard water lakes; sometimes on moist earth at margin of lakes. Mich., Wis. Nostoc microscopicum Carmichael (see Harvey in Hooker 1833, p. 399) Pl. 120, Figs. 3-5 Colonies minute, blue-green or olive-green, globose or ovoid to [ 523 | somewhat irregular. Trichomes relatively loosely entangled in a colorless mucilage. Cells globose, (4.5)-5-8 in diameter; frequently not adjoined but loosely arranged in a series. Heterocysts subspher- ical or ovate, 7.3» in diameter. Gonidia ovate or subspherical, 6-7 in diameter, 10-15, long; with smooth walls. Colony 1-9 mm. in diameter. Subaerial or growing on pebbles in running water or floating and entangled among filamentous algae; common. Mich., Wis. Nostoc muscorum C. A. Agardh 1812, p. 44 Pl. 120, Fig. 6 Colony a brown, lumpy or tuberculose membrane, firm and leathery when growing:on moist soil. Trichomes crowded and much entangled. Cells variable in shape, subcylindrical, barrel-shaped, or subglobose; constricted at the cross walls; 3-4 in diameter, 5.4-6.5p long. Heterocysts globose or compressed-globose, 6-7 in diameter. Gonidia ovate, in a series, with smooth ochraceous membranes. Occurring in swamps and in shallow water of lakes, mostly soft water; common. Mich., Wis. Nostoc paludosum Kuetzing 1850, p. 1 Pl. 121, Figs. 1-3 Plant a minute, oblong or subspherical colony in which a few trichomes are loosely or (when young) tightly coiled in a wide and copious gelatinous investment. Cells barrel-shaped, 3-4 in diameter; cell contents yellowish or olive-green. Heterocysts ovate, 4-5p in diameter, 6» long. Gonidia ovate, in short series; with a smooth membrane; 4—4.5 in diameter, 6-8» long. Colony 1 mm. or less in diameter. In ditches and Sphagnum bogs; caught among mosses and mats _ of filamentous algae. Wis. Nostoc pruniforme C. A. Agardh 1812, p. 45 Pl. 120, Figs. 7, 8 A spherical or ovate colony of loosely entangled or sometimes radiating trichomes inclosed in a copious and firm gelatinous matrix; olive-green when young and changing to a black-olive in age. Cells spherical or compressed-spherical to barrel-shaped; 4-6-(7.5) in diameter, 4-7, long; cell contents blue-green or gray-green. Hetero- cysts globose or compressed-globose, 6-7 in diameter. Gonidia spherical, about 10» in diameter. This species is common in hard water lakes and slow-flowing [ 524 ] streams, rare on recently inundated soil and on moist earth from which the water has receded. The colonies often appear as marble- like bodies scattered over the bottom among submerged. grass, reeds, etc., sometimes in large numbers so that one can scoop them in double handfuls. Although the average size is 1-2.5 cm., the colonies may attain a diameter of 5 cm. Not infrequently they are mistaken for reptile eggs. Mich., Wis. Nostoc punctiforme (Kuetz.) Hariot 1891, p. 31 Pl. 121, Figs. 4,5 A small, usually attached, colony of very compactly entangled trichomes in a colorless, soft mucilage; the linear arrangement of the cells frequently not discernible. Cells compressed-globose, 3.2—4p. in diameter. Heterocysts globose, 4.5—-6y in diameter. Gonidia ovate or oblong; 5-6, in diameter, 5-8p long. Attached to large filamentous algae and to leaves and stems of submerged aquatics in hard water lakes. This species also occurs as an endophyte or a symbiont with lichens and some cycads. Mich., Wis. Nostoc sphaericum Vaucher 1803, p. 223 Pl. 121, Figs. 6-9 A globose or tubercular, olive-green colony when young, becoming flattened and somewhat membranous and brown in age; trichomes densely entangled; cells globose, 4-5y in diameter; heterocysts spherical, 7.4» in diameter; gonidia solitary or in very short series (3-4 together), ovate, 5-7 in diameter, 10» long, with a smooth brown wall. The colonies become as much as 5-6 cm. wide under favorable conditions. The species should be compared with N. pruniforme, an aquatic species, but one which sometimes appears in the same habi- tats as N. sphaericum. Growing on soil at the margins of lakes; in marshy places among grasses; in thalli of Ricciocarpus. Mich., Wis. Nostoc spongiaeforme C. A. Agardh 1824, p. 22 Pl. 121, Fig. 10 A globular colony of loosely entangled trichomes when young, becoming lobed, expanded, warty and bullate, especially when grow- ing on damp soil, the color changing from blue-green to brownish- green. Cells variable in shape within the same colony, subglobose to barrel-shaped and cylindrical; 3.4-5p in diameter, 5.4-6.5n long. Heterocysts ovate to oblong or subglobose, 4.8-8» in diameter, 7.2 [ 525 ] long. Gonidia oblong or ovate; formed in a series and becoming loosely arranged; 6-7 in diameter, 8-10, long. Growing on damp soil in marshy places; near margins of lakes. Mich., Wis. Nostoc verrucosum Vaucher 1808, p. 225 Pl. 121, Figs. 11-18 A globular or bullate, verrucose and warty, leathery mass, many colonies sometimes coalescing to form a large olive-green or brown, somewhat membranous expansion on soil or on submerged sub- strates, solid at first but becoming hollow. Trichomes densely en- tangled, especially in the outer firm layers of the colonial mucilage, less compact inward; straight and radiating, frequently with indi- vidual sheaths distinct. Cells compressed-spherical or disc-shaped, 3-4 in diameter, 2.5-4y long. Heterocysts spherical, 6. in diameter. Gonidia ovate, 5u wide, 7p long. Growing in 27-85 feet of water in semi-hard water lakes; some- times large colonies are found floating or washed onto beaches of lakes; also reported growing on rocks near a waterfall. Mich., Wis. WOLLEA Bornet & Flahault 1888, p. 223 An attached tubular, saccate-cylindric, gelatinous colony of macro- scopic size in which unbranched, simple trichomes of ovate or cylindrical cells lie parallel, their sheaths confluent with the soft colonial mucilage; heterocysts intercalary, or terminal through vege- tative fragmentation of the trichome; gonidia ovate, solitary or in a series, either adjoining the heterocyst or distantly removed from it. Wollea saccata (Wolle) Bornet & Flahault 1888, p. 223 Pl. 122, Figs. 1, 2 Characteristics as described for the genus. Plant mass irregularly tubular or bullate, closed at the top, at first attached (usually in shallow water ), later expanding and forming soft, gelatinous masses floating at the surface. Trichomes compactly arranged, mostly paral- lel with the long axis of the colony, not contorted and twisted but commonly curved. Cells ovate to subcylindric; constricted at the cross walls; varying in their diameter throughout the length of the trichome; 3.6—4.2-(5) in diameter, 5-10u long. Heterocysts ovate to subcylindric; solitary; terminal or intercalary; 4-5p in diameter, 6.5-91 long. Gonidia oblong or subcylindrical, with thin, smooth walls; usually in a series of 3-5, rarely solitary; either near the hetero- cysts or distant from them. This plant, although rare, has wide distribution in the United [ 526 ] States (Massachusetts and New Jersey to South Dakota). I have collected the species in southern Louisiana and in Panama. Attached to the sandy bottom of lakes in shallow water. Wis. NODULARIA Mertens, in Jiirgens 1822, Dec. 15, No. 4 A sheathed filament, either solitary among other algae or forming thin expansions or tufts, aquatic or subaerial, on moist soil; cells disc-shaped or compressed spheroidal, constricted at the cross walls; heterocysts similarly compressed, about 14 of the width in length; gonidia spherical or disc-shaped, occurring in short (sometimes long ) series, intercalary. Key to the Species Filaments 4—6u in diameter; gonidia 6-8» in diameter. N. Harveyana Filaments 8-12—(18) in diameter; gonidia 12” in diameter... N. spumigena Nodularia Harveyana (Thw.) Thuret 1875, p. 378 Filaments usually solitary; nearly straight, sometimes flexuous but not entangled or coiled. Sheaths colorless and thin, usually close but sometimes diffuent and becoming indistinct. Cells 4-6» in diameter, 14 the diameter in length or, before division, nearly as long as broad. Apical cell obtusely conical. Gonidia nearly spherical or compressed-spheroidal; about 8» in diameter; yellowish-brown in color. Tychoplankter; in shallow water. Wis. Nodularia spumigena Mertens in Jiirgens 1822, Dec. 15, No. 4 P]. 122, Figs. 3-5 Filaments usually entangled and clustered in a loose, gelatinous mass; sometimes solitary; 8-12, in diameter. Cells disc-shaped, very much compressed; constricted at the cross walls; 6-7.8-(10)» in diameter, 5.6 long. Gonidia intercalary but not necessarily near the heterocysts; 12, in diameter, 8—-9y, long. Uncommon; found among algae in lakes of especially hard water; also adhering to the culms of rushes submerged in shallow water. Wis. APHANIZOMENON Morren 1838, p. 11 Filamentous; united to form fusiform or plate-like bundles and flakes of parallel trichomes, which are free-floating. Trichomes relatively short, tapering very slightly at both ends. Cells quadrate- [ 527 ] rectangular, constricted at the cross walls. Heterocysts cylindric, usually but one (rarely 2) in each trichome. Gonidia cylindrical, truncate at the apices; only one in each trichome; located in the median region but not adjacent to the heterocyst. Aphanizomenon flos-aquae (L.) Ralfs 1850, p. 340 Pl. 122, Figs. 6-8 Trichomes parallel, tapering at both ends; united in bundles or fiakes to form macroscopic colonies of few or hundreds of plants. Cells 5-6 in diameter, 8-12 long. Heterocysts oblong or cylindrical, scattered in the midregion of the trichome; 7» in diameter, 12-20p long. Gonidia cylindrical; formed near the middle of the trichome but not adjacent to the heterocyst; 8» in diameter, 60-75y long. This plant is a frequent component of water blooms and in favor- able habitats may become super-abundant. Hard water lakes in which there is a high nitrogen content and an adequate supply of carbon dioxide, either free or available in half-bound carbonates, may become biologically unbalanced by excessive growth of this plant. The cells have pseudovacuoles which permit the trichomes to float high in the water, where they form sticky masses, that are sometimes many square feet in extent. Either alone or in accompani- ment with Microcystis, aeruginosa and Anabaena spiroides, this plant is not infrequently responsible for oxygen depletion in small lakes and bays, resulting in great loss of fish. The occurrence of this species is so consistently related to hard water lakes that it may be used as an index organism for high pH, and usually a high nitrogen and carbonate content (especially when the plant appears as a water bloom). Aphanizomenon flos-aquae is rarely found except in eutrophic lakes or in polluted, hard water, slow-flowing streams. An exception to this was found in Rahr Lake, Vilas County, Wisconsin, where there was a visible, although not abundant, bloom in August, Rahr Lake is a semi-hard water body with an acid marginal mat. This species may remain alive all winter in the vegetative state, sometimes thriving under ice; as with Oscillatoria rubescens, there is some evidence that such growths bring about depletion of oxygen in shallow lakes, poorly illuminated because of coverage by ice and snow. The blue-green algae are poor oxygenators in any case. Also the gonidia may carry the plant over a period of unfavorable en- vironmental conditions. Their germination and the relation of the gonidium to bundle-formation have been carefully studied under laboratory conditions by Rose (1934). Mich., Wis. [ 528 ] CYLINDROSPERMUM Kuetzing 1843, p. 211 Filaments straight, curved, or loosely entangled, each surrounded by a soft film of mucilage which is confluent with others, forming an expanded mass of indefinite shape on soil or on submerged sub- strates. Heterocysts ovate or ellipsoid, one at either end of the trichome, or at only one end. Cells cylindric or barrel-shaped and constricted at the cross walls. Gonidia ovate, ellipsoid, or sub- cylindric, adjoining the heterocyst, solitary or several in a series with smooth, punctate, or granular calls; inclosed by a thick, close sheath. Key to the Species 1. Conidia ocepering, ina: series:____ >= eae 2 i, Gonidia salitasy: aarely 2: together <= es = es 3 2. Cells 4—5u in diameter; gonidia 8—10u in diameter________ C. catenatum 2. Cells 2.3-3.54 in diameter; gonidia 4—5.5u in diameter______ C. Marchicum a. Conidia cyludrical or subcylindric-= S20 sss ee ee 4 3. .Gonidia, ellipsnid Or ovate. 6 4. Cells 1.8—2u in diameter; gonidia subcylindric, Buh Ot Sr rina amMetel ooo. 4. 2-2. Ree ee ee C. minimum 4. Cells larger, 3.8-4.5-(6) in diameter; gonidia eylindries| og subcylndric.. 3a 5 5. Gonidia cylindrical, with smooth walls._____________________--_-------- C. stagnale 5. Gonidia subcylindric, with roughened, punctate walls__________ C. majus 6. Gonidia with punctate walls when mature_______________---__---_------------------- 7 GsiGonidianwathesmoothwalls:__---- ee sere ee ee 8 ea (GOmiGta Gp line Glam ete Trea C. minutum i Gonidia 14-3, 1m diameter ee C. majus 8. Cells 2-2.54 in diameter; gonidia 8-94 in diameter________.. C. minutissimum 8%) Cellsvand conigiallarger SS 9 9. Gonidia 9-12» in diameter, 10-20u long —_.-_--_-_-_-__ C. muscicola 9. Gonidia 12—14y in diameter, 20-384 long —_.____-__--_ C. licheniforme Cylindrospermum catenatum Ralfs 1850, p. 338 Pl. 122, Figs. 9, 10 Filaments united by their confluent mucilage to form dark green patches on submerged aquatics or on damp soil. Cells rectangular to short-cylindric; slightly constricted at the cross walls; 4-5y in diameter, 4-7 long. Heterocysts ovate to ellipsoid, 4-5y in diam- eter, 4-7» long. Gonidia oblong; formed in a series adjacent to the heterocysts; with a smooth brownish wall when mature; 8-10» in diameter, 14-18, long. “ On aquatic vegetation; tychoplanktonic. Mich., Wis. Cylindrospermum licheniforme (Bory ) Kuetzing 1847, p. 197 Pl. 131, Fig. 14 Filaments entangled and forming an expanse of macroscopic [ 529 ] proportions, dark green in color. Cells short cylindric; constricted at the cross walls; 2.5-4.21 in diameter, 4-5. long. Heterocysts elon- gate, 5—6y in diameter, 7—-12u long. Gonidia solitary, elongate- ellipsoid to oblong; the wall thick and smooth; 12—14, in diameter, 20—38, long. On submerged aquatic plants or on stones which are encrusted with sediment. Mich., Wis. Cylindrospermum majus Kuetzing 1843, p. 212 Pl. 122, Figs. 11, 12 Filaments entangled to form dark green mucilaginous patches. Cells short-cylindric; slightly swollen and constricted at the cross walls; 3.7-51 in diameter, 4-6. long. Heterocysts elongate, little larger than the vegetative cells, up to 10u long. Gonidia ellipsoid to subcylindric, with a roughened and punctate wall; 14.8, in diameter, 27 long, including the sheath. In several soft water and acid lakes and pools. Wis. Cylindrospermum Marchicum Lemmermann 1910, p. 196 Pl. 122, Fig. 13 Filaments entangled, forming small mucilaginous patches. Cells short-cylindric; slightly constricted at the cross walls; 2.5-3.5 in diameter, 7.4-8.54 long. Heterocysts ovate to subquadrate-ovate, 2.5-3u in diameter, 3-4 long. Gonidia ovate to subcylindric; in a catenate series adjoining the heterocyst; with thick smooth walls; 45.5 in diameter, (12)-14.8-16, long. This plant should be compared with C. catenatum from which it differs but very slightly, chiefly in size. It was originally described as a variety of that species. On moist substrates and on vegetation in shallow water. Wis. Cylindrospermum minimum G. S. West 1914, p. 1016 Pl. 122, Figs. 14, 15 Filaments solitary, or in small clusters, straight or gracefully curved; cells rectangular to short cylindric, 1.8-2 in diameter, 1.8-3.54 long; heterocysts subglobose to ellipsoid, 2 in diameter, 2.5—2.7 long; gonidia solitary subcyclindric, 3.5—3.8 in diameter, 8—9p long, with a thick smooth wall. This species was originally described from high altitudes in the Andes. Such a record naturally casts doubt on the assignment of our specimens, but they agree so well with West's description that the disposition seems justified. I have not seen the type specimens for comparison. Rare in tychoplankton. Wis. [ 530 ] Cylindrospermum minutissimum Collins 1896, p. 120 Piast} Fig. 13 Filaments loosely entangled, forming a thin blue-green skein. Vegetative cells quadrate-cylindric; not constricted at the cross walls; 2-2.5. in diameter, 4-5p long. Heterocysts elongate, 4, in diameter, 6-8» long. Gonidia solitary or in pairs; ellipsoid; the wall smooth; 8-9, in diameter, 18-20, long. On mats of algae in shallow water; tychoplankter. Wis. Cylindrospermum minutum Wood 1874, p. 39 Filaments much entangled in a mucilaginous expanse; forming bright blue-green to dark green patches on submerged aquatics; frequently scattered in minute clusters among other algae. Cells short-cylindric or slightly swollen, with constrictions at the cross walls; 3-4, in diameter, 3.5-4.8, long. Heterocysts ovate or sub- globose, 5-7 in diameter, 7-8, long; hirsute, with long radiating gelatinous fibrils. Gonidia ovate, 6-7» in diameter, 16-19, long, with a punctate or granular wall. Common in several acid or soft water lakes and small ponds. Mich., Wis. Cylindrospermum muscicola Kuetzing 1845, p. 173 Pl. 122, Fig. 16 Filaments entangled in a mucous expanse, forming dark green patches on submerged aquatics (Potamogeton, Elodea, Ceratophy- llum). Cells quadrate to cylindric; with slight constrictions at the cross walls; 3.5-5.5p in diameter, 46.5, long. Gonidia broadly ovate; with thick, smooth wall; 9-12n in diameter, (9)—16-20, long. A rather common species, occurring mostly in hardwater habitats, alkaline swamps, and shallow lakes. The broadly ovate gonidia are characteristic. Mich., Wis. Cylindrospermum stagnale (Kuetz.) Bornet & Flahault 1888, p. 250 Pl. 122, Figs. 17, 18 Filaments entangled or parallel in a mucilaginous expanse, at- tached or floating. Trichomes with cells constricted at the cross walls. Cells slightly swollen, 3.8-4.5-(6) in diameter, 7-13.4u long. Heterocysts globular or elongate, 6-7 in diameter, 7-16 long. Gonidia ovate or sybcylindric; with thick, smooth wall, (8)-10- 15-(16) in diameter, 19-21.6-( 40)» long. This is the most common species of the genus in our collections. It is found on or among aquatic vegetation such as submerged mosses, and in shallow water on dead and decaying grasses and [ 531 ] culms of rushes. At first the plant mass is attached and spreading over the substrate, but soon becomes free-floating, forming muci- laginous flakes. Mich., Wis. Cylindrospermum stagnale var. angustum G. M. Smith 1916, ‘p. 481 Pl. 123, Fig. 1 A form with gonidia smaller than in the typical plant; vegetative cells 4-4.5 in diameter, 8-10, long; heterocysts 5.5-5.6» in diam- eter, 7-11 long; gonidia 7-9 in diameter, 18—-25y long. Benthic and tychoplanktonic. Wis. AULOSIRA Kirchner 1878, p. 238 Trichomes solitary or loosely clustered in small bundles, inclosed in a thin but definite sheath which is closed at the ends. Trichomes the same diameter throughout or narrowed in the midregion and larger toward the apices. Vegetative cells rectangular to short- cylindric, or somewhat barrel-shaped. Heterocysts intercalary; round, ovate, or subcylindric. Gonidia 1 to several in a series, some- times adjacent to the heterocysts. Aulosira laxa Kirchner 1878, p. 238 Pl. 123, Figs. 2,3 Filaments straight or slightly curved; 8» wide; usually solitary but sometimes in 2’s or 3’s, entangled and parallel, with thin, color- less, and close sheaths which are somewhat diffluent and not lamel- late. Cells short and discoid or as long as wide (rarely a little longer); 6-7.2» in diameter, 3-8 long; much constricted and often not adjoined at the cross walls; sometimes forming a double series for a short distance in the sheath. Heterocysts quadrate to angular- globose, 7.5, in diameter. Gonidia solitary or in series of 2-3; cylin- drical with rounded ends; 5-7.5p in diameter, 16-19, long. Entangled with other algae, forming soft gelatinous expanses on submerged sticks, etc. Wis. FAMILY SCYTONEMATACEAE The chief characteristic of the sheathed plants which comprise this family is their habit of forming false branches. The filaments are all uniseriate, but in Desmonema and Diplocoleon (not repre- sented in our collections), more than one trichome is inclosed by a single sheath. All the genera except 2 (Plectonema and Spelaeopo- gon) have heterocysts. These determine the point of branch devel- [ 532 ] opment in some forms, whereas in others the branching occurs between the heterocysts. The branch arises when hormogonia in the primary filament proliferate and produce series of cells that push out laterally through the sheath, often continuing to form successive branches. Occasionally branches arise in pairs when adjacent ends of two hormogonia proliferate. The sheath is usually firm and definite and sometimes lamellate. It may be colorless or ochraceous. In general, the cells are quadrate or short-cylindric, although in some species they are somewhat barrel-shaped and constricted at the cross walls. Key to the Genera iPetlcterocysts, wantin SS Plectonema 1. Heterocysts present ____——_________-_-__--_____________-__-—— 2 2. Heterocysts basal (with intercalary heterocysts sometimes also present; {oy gebavel OUR S2 520s) ee Microchaete 2. Heterocysts all intercalary; false branching frequent ——___________ 3 ey) . Branches arising in unilateral pairs, about midway between two heterocysts (sometimes branches at the heterocysts also); sheath Hsiallydlamellates=ees sete Scytonema . Branches arising singly, just below a heterocyst or a series of them. 4 4, Filaments aggregated, somewhat radially arranged in a mucilaginous layer; branching regularly dichotomous; heterocysts solitary Diplonema 4, Filaments solitary or aggregated, sometimes forming free-floating, cottony tufts; branching irregular; heterocysts solitary or 2-4 in IS OTIEGS- 4 5:75 tee ae ee as On eee ke eee Tolypothrix SCYTONEMA C. A. Agardh 1824, p. xxii A falsely branched, usually thick-sheathed, filament, the false branches ordinarily developing in pairs (rarely singly) between the heterocysts (and sometimes also at the heterocysts ); forming wooly mats or tangled clots. Trichomes solitary within the sheath, forming hormogonia in the branches. Cells quadrate or short-cylindric. Heterocysts subglobose or quadrangular-globose. Gonidia rare; glo- bose or ovate; about the same size as the vegetative cells. Sheaths sometimes homogeneous but in most species definitely lamellated, with the layers either parallel or diverging; hyaline or, especially in the main filament, ochraceous. This genus should be compared with Tolypothrix. Scytonema mirabile, for example, seldom forms branches in pairs but singly, as in Tolypothrix. ie) Key to the Species 1. Sheaths very wide, forming lateral, wing-like expansions S. alatum 1. Sheaths not forming wing-like expansions —____--------------—_--------- 2 [ 583 ] 2. Sheaths lamellate, the lamellations diverging ..________ 3 2. Sheaths not lamellate, or with lamellations parallel __.__________-_________ 5 3. Filaments 18-30-—(36) in diameter; cells 6-124 wide... S. myochrous SaMilamentst smaller’) 110i 22 Sere ee ee ee 4 4 . Forming free-floating clots with filaments more or less radiating from a common center, 10-15 in diameter_______________- S. tolypothricoides 4, Forming attached, wooly expanses; filaments 15-214 in diameter__S. mirabile 5. Cells very short, about 1% their width in length; filaments very coarse and wiry, seldom branching. __- = S. crispum 5: (Cells longer; branching) frequent= = ee S55 aft dc ec net 6 6. Heterocysts ovate or subglobose; filaments 18—24y in diameter____ S. coactile 6. Heterocysts quadrate to cylindrical; filaments 19 1G usin’ diameters sans eke eel EY a Se ee ee ve S. Archangelii Scytonema alatum (Carm.) Borzi 1879, p. 378 PI. 123, Figs. 4,5 Filaments forming dark olive-brown, wooly mats or tufts. Branches of trichomes in pairs between the heterocysts, branches relatively short. Cells short cylindric or barrel-shaped; 9-15y in diameter, 8-15» long. Heterocysts subglobose, tinged with yellow-brown. Sheaths wide; much lamellated, with the layers diverging, forming ‘wings’; with decided constrictions here and there, especially at the heterocysts. Filaments 24-66, in diameter. Tychoplankter. Mich., Wis. Scytonema Archangelii Bornet & Flahault 1887, p. 92 Pl. 123, Figs. 6, 7 Filaments in fascicles or tufts, forming brownish or gray mats and cushions. Trichomes with long, gracefully curved branches arising singly at the heterocysts, or more commonly in pairs between the heterocysts. Cells quadrate; without constrictions at the cross walls; 12-18, in diameter, 14-20, long. Heterocysts quadrate or cylindrical; either colorless or ochraceous. Sheaths thin, close, hyaline. Filaments 12-16, in diameter. Tychoplanktonic and on shore. Wis. Scytonema coactile Montagne in Kuetzing 1849, p. 305 Pl. 124, Figs. 1-3 Filaments forming thick, blue-green skeins or film-like expansions. Trichomes frequently branched, with the solitary habit predominat- ing; false brenches long and spreading. Cells quadrate or com- pressed barrel-shaped, 12-18, in diameter, 5.8-7.5. long; cell contents a deep blue-green or yellow-green, especially in the distal ends of the branches. Heterocysts scattered and infrequent; olive- [ 534 ] brown in color; ovate or subglobose; 15.6 in diameter, 19.5 long. Sheaths close and firm; colorless or light olive; not lamellate. Fila- ments 18—23.4 in diameter. All our specimens of this plant have been collected in Sphagnum bogs and soft water lakes. Wis. Scytonema crispum (C. A. Ag.) Bornet 1889, p. 156 [S. cincinnatum Thuret] Pl. 124, Figs. 4-6 Filaments forming dark brown or gray-brown wooly mats; seldom branched; coarse and wiry. Trichomes straight or somewhat bent, not tapering, frequently constricted and forming hormogonia. Cells very short, disc-like; 14-30. in diameter, 2.4-3 long. Heterocysts spherical, frequent, olive-green or yellowish, 19. in diameter. Sheath thick (3.5), firm, brown, not lamellated. Filaments 16-36 (mostly 20-30») in diameter. Frequent in hard water lakes. Forming tangled, brown clots among filamentous algae or submerged aquatics. In sections of the filament which are unbranched and in which no heterocysts occur the plant has the appearance of a coarse Lyngbya. Wis. Scytonema mirabile (Dillw.) Bornet 1889, p. 155 [S. figuratum C. A. Agardh] P]. 124, Figs. 7, 8 Filaments forming brown or dark green wooly tufts, either aquatic or terrestrial. Trichomes with long, infrequent branches usually arising singly either at the heterocysts or between heterocysts. Cells quadrate in the main filaments, cylindrical in the branches; 6-12, in diameter, 8-14p long. Heterocysts quadrate-globose to cylindric; about the same size as the vegetative cells. Sheaths thin and close in the branches, thick and with diverging lamellations in the main filaments. Filaments 15-20, in diameter. One of the most common species of Scytonema found in our region. It occurs in both soft and hard water lakes. Many times the plants have the appearance of a Tolypothrix, especially in the habit of branching. Mich., Wis. Scytonema myochrous (Dillw.) C. A. Agardh 1812, p. 38 Pl. 124, Fig. 9; Pl. 125, Figs. 1, 2 Filaments forming dark brown turfy or tomentose patches. Tri- chomes long and flexuous in wide sheaths. Cells quadrate to cylin- dric in the older portions, disc-shaped or compressed-globose in the [ 535 ] distal ends of the branches; 6-12, in diameter, 4-14u, long. Hetero- cysts quadrangular-globose, yellow-brown in color, the contents yellow-green, sheaths thick and lamellated, with layers diverging; brown in color. Filaments 18-36 wide. This species is recorded frequently from aerial habitats. On logs and stones; tychoplankter. Mich., Wis. Scytonema tolypothricoides Kuetzing 1849, p. 307 [S. mirabile var. tolypothricoides (Kuetz.) Lobik 1915, p. 42] Pl. 123, Figs. 8,9 Filaments forming dark blue-green or brown floating, cottony clots. Trichomes more or less radiating from a common center; freely branched, the branches mostly in pairs. Cells quadrate to subcylin- dric in the older portions, compressed and much shorter than wide in the branches; 6.8—12, in diameter. Heterocysts quadrate or ovate; about 10, in diameter. Sheaths wide, lamellate, at first colorless, be- coming brown or orange colored. Filaments 10-15, in diameter. Common in the plankton of a variety of lakes, mostly soft water. Appearing as Tolypothrix-like clots floating among aquatic vegeta- tion near shore. Mich., Wis. TOLYPOTHRIX Kuetzing 1843, p. 227 A sheathed, falsely branched trichome; solitary or, more usually, forming cottony tufts and expansions; the false branches mostly long and flexuous, arising from just below a heterocyst. Cells quadrate to cylindric or barrel-shaped, constricted at the cross walls. Hetero- cysts quadrangular, globose, or subglobose, single or in series. Sheath firm and thin, or somewhat gelatinous and lamellated. Gonidia ovate to elliptic, or subglobose; with a thin membrane; often occurring in a series. Key to the Species 1. Sheaths thick, about as wide, or wider than the ‘diameter of the trichome +. ~/2. e ek Se ) 1. Sheaths thin, usually close, but lamellated in some; less than the diameterof the, trichome dm width: Sos 2 eee 3 2. Trichomes 5.5—9y in diameter; cells barrel-shaped; SHG ALS INO’ SHC Kye! ... - =e ee eee ee S. mesentericum 2. Filamentous arrangement of cells apparent; more elongate branches —_- i} 3. Filaments 40-70 wide; plants mostly aquatic; branches short. and.: broad :2te= Te 6 te Sar aes eee Dera es Pe he S. mamillosum 3. Filaments 27-371 wide; plants mostly terrestrial; branches long and curved ——______—_————— S. turfaceum Stigonema mamillosum (Lyngb.) C. A. Agardh 1824, p. 42 Pl. 130, Figs. 1-3 Filaments much-branched, forming attached, dark green wooly tufts, or scattered in small entanglements among other floating algae, composed of several series of globose or ellipsoid cells; branches short, irregularly developing, narrowed at both the base and in the distal region; heterocysts numerous, compressed-ovate, cut off laterally from the vegetative cells; sheath wide, lamellate, becoming yellowish or olive-brown in age; cells 14-17, in diameter; filaments 40-70» wide; hormogonia developing in special short branches. Our collections have all been made from soft water habitats. Common in several lakes, usually attached to submerged wood; sometimes forming small clots among floating algae. Mich., Wis. [ 547 J Stigonema mesentericum Geitler 1925a, p. 184 Pl. 130, Fig. 4 A gelatinous, cushion-like mass, composed of filaments with very short, broad, irregularly developed branches in which series of glo- bose or ovate cells are arranged without definite order; heterocysts compressed globose, intercalary or lateral; cells 6-12 in diameter; sheath close, thick and lamellate, inclosing small groups of cells which form irregular lobes from the main axis; filaments 25-35 wide. Tychoplankter; in semi-hard water lakes. Wis. Stigonema ocellatum (Dillw.) Thuret 1875, p: 380 [Incl. S. tomentosum (Kuetz.) Hieronymus 1895, p- 166] Pl. 130, Figs. 5, 6 Filaments forming brown tufts or cottony masses, with long, nar- row and curved branches; trichomes partly uniseriate; heterocysts mostly lateral; cells quadrate-globose to globose, with intercellular connections, 20-30, in diameter in the principal filament, each cell inclosed by a conspicuous individual sheath which is either colorless or brown; cell contents blue- or olive-green to bright marine-green in the young cells of the branches; sheath wide and lamellated, brown in the older parts, colorless in the branches; filaments 35—45y wide. Stigonema ocellatum is a very common species, appearing in a great variety of fresh-water and aerial habitats. It is often a con- spicuous component of the algal flora in habitats where desmids abound, forming brown wooly mats on and over submerged aquatics such as the culms of Scirpus, Utricularia, decaying leaves, etc. This is the only common species of Stigonema which has but one series of cells in the filament (rarely showing a double series for short distances). Mich., Wis. Stigonema turfaceum (Berkeley ) Cooke 1884, p. 272 Pl]. 129, Fig. 5 Filaments much-branched, forming dark-colored, cushion-like masses, the branches about the same diameter as the principal filaments, long and curved, with hormogonia produced distally; trichomes of from 2-4 series of globose or much compressed- globose cells which in the hormogonia are 12, in diameter; hetero- cysts intercalary or lateral, much compressed; sheaths wide, lamel- late and yellow-brown in age; filaments 27-37,» in diameter. Tychoplankter. Mich., Wis. [ 548 ] FISCHERELLA (Bornet & Flahault ) Gomont 1895, p. 52 A branched and sheathed filament with a stouter, prostrate portion giving rise to vertically elongate, much narrower, curved or straight branches in which 1 or more hormogonia are formed; cells sub- globose, quadrate, or cylindrical, usually loosely arranged in 1 to several series in the principal filament, in a single series only in the branches; hormogonia with cells closely adjoined and usually in- creasing in diameter toward the apices; heterocysts globose, barrel- shaped, or quadrate; sheaths either colorless or brownish, homo- geneous or lamellated. This genus is considered by some to be unseparable from Stigo- nema and is, therefore, often included with it as a subgenus. When given genus rank it is differentiated principally by the unilateral arrangement of the branches, which are distinctly smaller than the main filament, and also by the habit of forming hormogonia in the apices of the branches. Key to the Species Main vfilament mostly, wiiserates = 2s. ee F. ambigua IM avin, dillewanverne Tentillawerneyey F. muscicola Fischerella ambigua (Naeg.) Gomont 1895, p. 49 Plant mass consisting of prostrate mats of interwoven filaments from which vertical fascicles arise; filaments 6-9, in diameter, giving rise to unilateral branches, which are grouped; sheaths colorless when young, becoming brownish; cells 2-3 in diameter, ovate or subglobular to quadrate in the main axis, rectangular in the branches, 4-6 times longer than wide; heterocysts cylindrical. On moist soil. Mich. Fischerella muscicola ( Borzi) Gomont 1895, p. 52 Pl. 130, Figs. 7, 8 Plant mass consisting of prostrate, irregularly spreading filaments, containing several series of cells, from which mostly unilateral and uniseriate branches arise; cells quadrate or subglobose in the main axis; branches 4—6y in diameter, developing hormogonia up to 100 in length; heterocysts globular or barrel-shaped, about the size of the vegetative cells; sheaths colorless or brownish, without lamella- tions; filaments 10-14, in diameter. In shallow water at the margin of ponds among filamentous algae and larger vegetation. Mich., Wis. [ 549 ] FAMILY RIVULARIACEAE The outstanding characteristic of plants belonging to this family is the pronounced tapering of the trichomes, which exhibit a distinct basal-distal differentiation. The sheath is firm, at least in the basal portion, and may be lamellate or homogeneous. There may be one or more trichomes within the sheath. In most forms there is a basal heterocyst or a short series of them (and rarely intercalary hetero- cysts as well), whereas in 2 genera some species are without hetero- cysts. The trichomes may be solitary or they may form colonial aggregates of spherical or hemispherical shape, or the thalli may be amorphous. In most forms there is an evident false branching which occurs immediately below an intercalary heterocyst. In at least one genus the branches lie semiparallel with the original trichome in the same sheath for some distance before they emerge. Branches may arise also by in situ proliferation of hormogonia. The presence or absence of gonidia is of taxonomic interest. These, if present, are adjacent to the heterocysts. Key to the Genera 1, Filaments numerous, closely arranged in radiate or parallel series within copious mucilage to form globular or hemispherical, free- floating worgattachedsecolonies= 1 sler es aes ae eee 2 PSbilamentsy arranged | otherwise ase sees orale eee eee oy eee Eee ee 8 2. Mucilage firm, often hard and lime-encrusted; akinetes not present; tnichomies often sparallel) compacted. 2) emer ee ee Rivularia 2. Mucilage soft (especially when the plants are mature); akinetes present; trichomes radiately arranged ________»__ Gloeotrichia (in part) 3. Trichomes contained in amorphous gelatinous mucilage; attached orgitee-Moating tes. Ate ce et! xn ee ee pak oe a ee mere eal 5 3. Trichomes not contained in amorphous mucilage; more or less solitary, or forming plant masses of definite shape 4 4, Colonial mass small, saccate and torn, with the investing mucilage lamellatetand! much folded’) 8 eee Sacconema 4. Colonial mass otherwise, large and expanded, at first attached, later free-floating, mucilage not lamellate or folded ___ Gloeotrichia (in part) BAlkimetes! salosen ies 28 20's ne Aaa § NGA) Se) teks te Pa 6 Dapakcinetes presents... = 4 eas 2 ot LE 5 ee Ld 7 6. Trichomes many, arising from a basal pseudoparenchymatous poron efithe: thalluss 26s se. CRAs a ee ee Amphithrix 6. Trichomes few together, not arising from a basal pseudoparenchy- miatousgthalllysy omnes. he sorties es). nist pee ee Calothrix (in part ) 7. Filaments freely branched, the branches inclosed within the sheath of the primary filament, forming dichotomously branched tufts; NOL TAepipiay tucbeesee whe eee Ses Cele tse te ee ree! Dichothrix 7. Filaments seldom branched; solitary or gregarious, sometimes form- ing stellate tufts; plants epiphytic on walls of other algae or inclosed in colonial mucilage; forming encrustations in aerialvhabitatse: sei tae ey bes oD Calothrix (in part) AMPHITHRIX Kuetzing 1843, p. 220 Thallus composed of erect, parallel, tapering trichomes from a basal pseudoparenchymatous tangle of closely appressed trichomes; heterocysts and akinetes wanting; plant mass often purplish. Amphithrix janthina ( Mont.) Bornet & Flahault 1886, p. 344 Pl. 131, Fig. 9 Characters as described for the genus; trichomes tapering to a fine, hair-like extremity, composed of rectangular cells; sheaths thin and colorless; cells 1.5—2.5u in diameter. Mich. CALOTHRIX C. A. Agardh 1824, p. xxiv ‘Trichomes tapering from basal heterocyst (rarely wanting) to a fine point in most species, abruptly ending in others. In some species the lower part of the trichome is cylindrical, only the apical region tapering. Vegetative cells shorter than wide below, longer than wide toward the apices; heterocysts subglobose or hemispherical, basal but sometimes intercalary also; gonidia (akinetes) often present, 1 or more in a series, adjacent to the basal heterocyst; sheaths firm, close, either homogeneous or lamellated, but not flaring away from the trichome (see Calothrix adscendens); filaments usually simple, sometimes with false branches from the midregion; plants either solitary or clustered to form stellate tufts, the basal portion of the plant lying approximately parallel with the substrate and then bend- ing away at a sharp angle (in most species); either epiphytic or endophytic (in the mucilage of other algae), growing on submerged or on exposed and moist rock surfaces, where extensive patches may be produced, sometimes becoming encrusted with lime. Key to the Species i: Akinetes present ee C. stagnalis iN eeeAtlcrnetecst a seers Gi nee oe a eA sc EB ee 2 2, Filaments definitely enlarged in the basal portion; sheaths some- ELMS LN MALeCs CONV A sect ete ae te te a ee 8 2. Filaments very gradually tapering, or cylindrical throughout much of their length and then tapering ——------—-----________________-----_-- 5 3. Filaments compactly arranged in common mucilage, forming a colonial expanse on aquatic substrates ___—_-_------_--________. C. Braunii 3. Filaments solitary, or in small tufts, intermingled among other algae, or epiphytic____________-— 4 4. Sheath close, without lamellations; scattered among Otherralpae == =e C. stellaris 4. Sheath wide, lamellated; plants attached in the mucilage Of other alee oo C. fusca [ 551 ] 5. Trichomes not tapering to a hair; short, abruptly ending C. atricha 5. Trichomes decidedly tapering, sometimes to a long hair 6 6. Filaments associated to form a colonial expanse C. parietana 6. Filaments solitary, or few together, scattered or epiphytic 7 7. Cells very short, 4-45 as long as wide; sheath brown _____C. breviarticulata i Cellsslonger-psheathycolorless\-- == = aan ED eee eee 8 8. Trichomes slender, 3.5-4u in diameter at the base; filaments DHRC ATE LEH. so ee teks Uh SOE: Sy eae URI ae Me cere C. epiphytica 8. Trichomes stouter, 12u in diameter at the base; filaments S24 evimiwdiameteyse sb.) ot Laces) Oe Saget eaace eth See ee) C. adscendens Calothrix adscendens (Naeg.) Bornet & Flahault 1886, p. 365 Pl. 130, Figs. 9-11 Filaments solitary or in small clusters, tapering from the base to apex, sheath wide, lamellated; heterocysts basal, 11, in diameter, 11.8, long; vegetative cells 9.24 in diameter, 7.4-8, long at the base; filament 12-18—( 24) wide at base. Attached to larger filamentous algae and other aquatic plants. Wis. Calothrix atricha Frémy 1930, p. 261 Pl. 129, Fig. 6 Trichomes short, solitary or in clusters of 3-4, curved and torulose, sheaths thin, colorless, not lamellated, slightly tapering to a blunt apical cell; heterocysts basal, usually in pairs, spherical, 9» in diameter; vegetative cells 7.4-81 in diameter at the base, 1-14 times as long as wide. Our plants are questionably assigned to this species originally described from Africa. The torulose character of the filaments and the shape of the cells, together with the characteristics of the sheath and the form of the apical region of the trichome, agree with the description. Wis. Calothrix Braunii Bornet & Flahault 1886, p. 368 PI. 181, Fig. 12 Trichomes parallel, gradually tapering to a point, compactly arranged to form a colonial expanse on submerged substrates; sheath thin and colorless; heterocysts hemispherical, basal; vegeta- tive cells shorter than broad or about as long, constricted at the cross walls, 6-7» in diameter at the base. On submerged vegetation and stones in hard water lakes. Wis. Calothrix breviarticulata West & West 1897, p. 240 PIP 132, Fig.l Filaments mostly solitary, tapering gradually from a broad base [ 552 ] to a long hair, 16, in diameter; sheaths thick, lamellate, discolored in age; heterocysts basal, hemispherical, 12» in diameter; cells 11-14, in diameter, very short, 145-14 as long as wide, contents blue-green. Attached to larger filamentous algae. Wis. Calothrix epiphytica West & West 1897, p. 240 Pl. 132, Figs. 2,3 Filaments either single or in small clusters, gradually tapering from base to apex, ending in a long hair; 5-7.5-(7.8) in diameter; sheaths wide, not lamellate; heterocysts basal, 4-5» in diameter; cells 4-5 in diameter at the base of the trichome, about as wide as long. On filamentous algae and submerged aquatics. Mich., Wis. Calothrix fusca (Kuetz.) Bornet & Flahault 1886, p. 364 Pl. 132, Figs. 4,5 Filaments strongly curved from short horizontal basal portions, attached in the mucilage of other algae, bulbous at the base, 11-14y in diameter, tapering to a long hair; vegetative cells 7—llp in diameter, 14 as long as wide; heterocysts basal, hemispherical, 9-10 in diameter. Attached in the mucilage of Coleochaete, Batrachospermum, and other algae inclosed in mucilage. Wis. Calothrix parietana (Naeg.) Thuret 1875, p. 381 Pl. 132, Fig. 6 Trichomes solitary or gregarious, forming dark brown patches on submerged substrates or in aerial habitats, tapering from the base, much twisted and contorted, with the basal portion of the trichome appressed on the substrate; vegetative cells very short, 5-10» in diameter, 2.53» long; heterocysts 6-10 in diameter, usually basal, quadrate-globose to hemispherical; sheaths firm, relatively thick and close, not lamellated, becoming yellowish-brown with age; filaments 10-12» wide. Attached to old logs and stones in running water; tychoplankton. Mich., Wis. Calothrix stagnalis Gomont 1895a, p. 197 PIMS2, Figs? Filaments usually gregarious in stellate clusters or tufts, rarely solitary, appressed to the substrate in the basal region but bent sharply or twisted to form an erect apical portion; trichomes tapering [ 553 ] gradually to a hair-like point from a basal heterocyst; cells short, rectangular to slightly swollen, with constrictions at the cross walls, 5-9 in diameter, shorter than wide below, becoming longer than wide in the apical region; heterocyst spherical or subspherical, basal, solitary or in pairs, 6-lly in diameter; sheaths thin, firm, gradually narrowed with the trichomes; gonidia 1-3 in series, adjacent to the heterocyst, 10.8 in diameter, 14-16, long; filament 8—(9)-10-(11), wide at the base. Common; attached to large filamentous algae such as Cladophora, Rhizoclonium, and Oedogonium. Mich., Wis. Calothrix stellaris Bornet & Flahault 1886, p. 365 Filaments solitary or clustered and radiately arranged, bent from the basal swollen portion and tapering to a fine hair from a hemi- spherical, basal heterocyst; sheaths thin, firm and close, colorless; cells 6-7 in diameter, constricted at the cross walls, 14-14 times as long as broad; heterocysts either solitary or in a series of 2-3; filaments 15-21, in diameter at the base. Attached to submerged plants. Wis. DICHOTHRIX Zanardini 1858, p. 297 In this genus the plant is composed of 2-6 tapering trichomes inclosed within a single sheath for at least a part of their length. They are usually solitary but sometimes form macroscopic, cushion- like masses or feathery tufts on submerged wood and stones, or on moist substrates; trichomes with basal heterocysts (sometimes inter- calary also), and with dichotomous false branching, a branch ex- tending for some distance within the same sheath as the principal trichome, then emerging in its own sheath and usually rebranching successively; cells quadrate, slightly swollen, or shorter or longer than their diameter, either constricted or not at the cross walls; tapering at least in the distal portion of the trichome; basal hetero- cysts connate or hemispherical; sheaths either thin and close or lamellated, sometimes with a bulbous base, tapering with the trichome or widely diverging toward the apex to form a funnel, according to the species. Key to the Species 1. Filaments 10—14, in diameter, with flexuous, Spread Gan cedlarattchesmm ee wrote ree cok x; voces Les hee ceen nese CMe en eee D. Orsiniana 1. Filaments larger, with straight or curved branches .......................00.c0000--. 2 2. Filaments coarse, 20—28u in diameter; branches bulbous at thet basca, pies Mem ne Maen kde Ee Ma a ca D. Hosfordii 2. Filaments narrower, (12)—15—18u in diameter; branches not’ bulbous’ atsthe base. .)s). scene ee D. gypsophila Dichothrix gypsophila (Kuetz.) Bornet & Flahault 1886, p. 377 Pl. 133, Figs. 1, 2 Either solitary among other algae or forming tufts and expanded strata, frequently encrusted with calcium carbonate; filaments re- peatedly branched, the branches parallel with the principal trichome and inclosed in the same sheath with it for a considerable distance; vegetative cells shorter than wide at the base and with convex walls, longer than wide toward the distal end and cylindrical without constrictions at the cross walls, 6-8, in diameter in the basal portion of the trichome; heterocysts subglobose or hemispherical, 10-12y in diameter; sheaths lamellated, at first close, then becoming funnel- shaped toward the distal end; filament (12)-15-18p wide at the base; penicillate tufts as long as 2 mm. This species varies in its sheath characters, apparently, for authen- tically named material which was compared with Wisconsin plants shows both close, tapering sheaths as well as flaring, funnel-forming sheaths. It should be compared with D. Hosfordii, a much larger plant with sheaths bulbous at the base. Forming tufts of filaments entangled among other filamentous algae in shallow water at the margin of marshy lakes. Wis. Dichothrix Hosfordii (Wolle) Bornet in Setchell 1896a, p. 190 Pl. 133, Figs. 3, 4 Plants penicillate tufts of stout, dichotomously branched filaments, 90-28 in diameter at the base; vegetative cells much shorter than their diameter, 10-15, in diameter at the base, 3-5p long, becoming cylindrical and several times their width in length in the distal region, which tapers to a hair-like point; heterocyst a short, broad cone, or hemispherical, olive or blue-green, 15-18 in diameter; sheaths lamellated and bulbous at the base, several trichomes within a sheath, the branches appressed for some distance, then emerging in their own sheath. This species is more common in our collections than D. gypsophila. It occurs among other algae in a number of both hard and soft water lakes. The greater size and the bulbous-inflated sheaths help to identify it. Mich., Wis. Dichothrix Orsiniana (Kuetz.) Bornet & Flahault 1886, p. 376 Pl. 133, Figs. 5, 6 Gelatinous, penicillate tufts, composed of slender trichomes in close and thick, lamellated, tapering sheaths; filaments branching freely, the branches extending for most of their length within the sheath of the principal trichome; trichomes subcylindric below, [ 555 ] tapering to a fine point distally; vegetative cells very short, 5-8 in diameter, 2-4, long, or quadrate; heterocysts subglobose or hemispherical, 8-10, in diameter; filaments 10-14, wide at the base. On moist earth or attached to or entangled among filamentous algae. Mich., Wis. RIVULARIA (Roth) C. A. Agardh 1824, p. 19 Filaments semiparallel or radiately arranged in copious, very firm mucilage, forming either semi-microscopic globose colonies or macroscopic, bullate or expanded masses which may be either solid or hollow; heterocysts all basal and the trichome tapering from them to fine points; frequently branched, the branches sometimes so disposed as to form transverse zones through the colonial mass; individual sheaths definite at the base but becoming diffluent toward the apex of the filament; gonidia lacking. Key to the Species Cells 4—7.5u in diameter; colonies lime encrusted... R. haematites Cells 9-12.5y in diameter; colonies not conspicuously lime encrusted..R. minutula Rivularia haematites (D. C.) C. A. Agardh 1824, p. 26 Pl. 131, Figs. 10, 11 Filaments united in attached, hemispherical colonies, inclosed by a firm mucilage and encrusted with lime, colonies frequently gre- garious and agglutinated to form an expanse as much as 8 cm. thick; filaments closely arranged and semiparallel, the false branches forming transverse tiers or zones; individual sheaths conspicuous below, firm and close, either colorless or yellow, becoming expanded and funnel-form above toward the periphery of the colony; cells 4-7.5u in diameter, twice the diameter in length in the lower part of the trichome, becoming 14 as long as wide in the apical region. On stones in lakes and flowing water. Mich. Rivularia minutula (Kuetz.) Bornet & Flahault 1886, p. 348 Pl. 136, Fig. 9 Filaments arranged in brownish, globular or hemispherical colonies, enclosed in firm mucilage, but rather loosely and radiately arranged within the colony and inclosed in wide, hyaline or brown- ish, lamellate sheaths, becoming funnel-form toward the periphery of the colony; trichomes tapering to a stout hair above from oblong or hemispherical heterocysts; cells 9-12.5 in diameter, quadrate below, becoming 3-4 times as long as wide in the apical region. Attached to submerged plants and wood. Mich. [ 556 j GLOEOTRICHIA J. G. Agardh 1842, p. 8 A free-floating or attached hemispherical or globose colony of radiating trichomes, tapering from basal heterocysts and much attenuated at the apices; colonial mucilage soft or rather firm according to species (but not rubbery and not so tough as in the genus Rivularia), either colorless or becoming ochraceous with age in some species; sheath of the trichome usually confluent but often evident in the basal part of the trichome; heterocysts solitary (rarely 2), basal as well as intercalary, globose to oval; vegetative cells short in the basal portion of the trichome but becoming barrel- shaped, longer and cylindrical distally; gonidia cylindrical, usually single, adjoining the heterocyst, rarely in a short series, the mem- brane thick and smooth. Species of Gloeotrichia are included with Rivularia by some authors. Separation is here arbitrarily made on the presence of the gonidia, Rivularia lacking them. The latter genus includes species which are always attached and which have very firm, sometimes hard mucilage, often encrusted with lime. The hemispherical col- onies of both genera are macroscopic in size and similar in general appearance. In Rivularia the colony may be hollow, and the radiat- ing filaments are in concentric zones as a result of false branching. In some species of Rivularia agglutinated and expanded gelatinous attached masses are formed. In Gloeotrichia the colonial mucilage is softer and the trichomes definitely radiate and not zoned. Branch- ing is less common. Whereas some Gloeotrichia may remain attached, most species become planktonic or free-floating, especially G. echinulata and G. natans. Key to the Species ae iGolonies elobular, planktonic... et ts G. echinulata 1. Colonies not planktonic or, if free-floating, not globular and burr-like____ 2 2. Colonies containing only a few trichomes; cells very long and cylindrical, rounded at the ends; a conspicuous granule at each GTOSSiavy alll fis Bit 2) eG Seay aa et oh Li Sao all G. longiarticulata 2. Colonies containing numerous trichomes; cells quadrate or slightly longer than wide, or shorter than wide in the basal portion; end walls not rounded or marked by conspicuous granules___ 3 3. Colonies globular or hemispherical, 1-5 mm. in diameter; attached, sometimes completely coating aquatic plants G. Pisum 3. Colonies irregularly globose or bullate, 5 mm. to 10 cm. across, becoming soft and irregularly expanded and floating when old___ G. natans Gloeotrichia echinulata (J. E. Smith) P. Richter 1894, p. 31 Pl. 134, Figs. 1, 2 A free-floating, spherical, gelatinous colony of many sheathed [ 557 ] trichomes radiating from a common center; trichomes tapering from a basal heterocyst to a fine hair-like point extending beyond the limits of the colonial mucilage and so giving a burr-like appearance; cells spherical or barrel-shaped at the base of the trichome, 8-10u in diameter, becoming long and cylindrical in the distal portion; cell contents with many pseudovacuoles; heterocysts spherical, 10n in diameter; gonidia cylindrical, 10-18» in diameter, up to 50y long, adjacent to the heterocyst; sheaths colorless, wide, without lamella- tions, covering approximately the lower third of the trichome. The colonies are macroscopic and appear as minute, dark, egg- like or burr-like bodies, opaque in the center and translucent at the periphery. The planktonic habit is associated with the pseudo- vacuoles, which are often numerous and large. As is well-known, those blue-green species which have a high degree of vacuolization show a great buoyancy, often floating at the very surface. Gloeo- trichia echinulata, like Aphanizomenon flos-aquae and Microcystis aeruginosa, often forms a dense suspension of thalli in upper lake levels. Such superabundant growths are frequently followed by unbalanced biological conditions as a result of the death and decay of plant masses. During mid-summer and throughout the warm season Gloeotrichia echinulata makes periodic blooms, sometimes becoming concentrated near the shore line and in shallow bays in such numbers as to form a veritable puree. This species undoubtedly begins its life cycle in a sedentary or attached condition, developing from gonidia of the previous genera- tion. The mechanics involved in the germination which determines the filament arrangement, the soft consistency of the colonial muci- lage, and the volume of the cell contents occupied by pseudovacuoles no doubt are responsible for the ready adoption of the planktonic habit. Hence conspicuous growths make a sudden appearance in lake plankton when large numbers of colonies become free-floating. Wind and water currents and probably a change in physiology also act to bring about a scattering and vertical distribution so that a dense surface bloom may disappear as quickly as it developed. Common in the plankton of many lakes, especially in hard water habitats. Mich., Wis. PGloeotrichia longiarticulata G. S. West 1907, p. 183 Pl. 134, Figs. 8-5 Thallus hemispherical and attached, containing relatively few, widely separated, and loosely arranged trichomes which taper to a very fine point; sheaths confluent with the colonial mucilage; cells elongate-cylindric with rounded ends, (4.5)-9.5 in diameter, 3-7 [ 558 ] times the diameter in length (in our specimens, with cells separated slightly from each other), with a conspicuous granule at each cross wall, contents not vacuolate; heterocyst subglobose to elongate- elliptic or ovate; gonidia short-cylindric, 14.81 in diameter, 27.3- (44) long with a yellowish membrane. The plant, found but once, is scantily represented in the collec- tion. The characteristics are distinctive, however, and agree closely with the description given by West; hence it is tentatively assigned to Gloeotrichia longiarticulata G. S. West. Subsequent collections are needed to confirm this identification. Attached to submerged aquatics. Wis. Gloeotrichia natans (Hedwig) Rabenhorst 1847, p. 90 Pl. 134, Figs. 6, 7 A soft, gelatinous, globose or bullate, attached colony, brown or olive-green in color, becoming free-floating and expanded to form irregularly shaped mucilaginous masses at maturity; filaments at first somewhat radiate, becoming irregularly arranged and entangled, very long and tapering from a basal heterocyst; cells barrel-shaped or subglobose below, becoming quadrate or subcylindrical distally, 7-10, in diameter; heterocysts globose or ovate, 8-12, in diameter; gonidia solitary, adjacent to the heterocyst, 12-18, in diameter, up to 250, long, with a thick wall and a sheath; basal sheath of the filament covering about a third of the length, lamellated, wrinkled, wide and funnel-shaped above. This species forms attached colonies as much as 10 cm. across under favorable conditions (quiet hard water and high tempera- tures). The mucilage is very soft, and the colonies expand and be- come floating masses by the time gonidia have reached maturity. Inasmuch as the plant mass soon fragments, this species is frequently collected in plankton catches, where it appears as irregular flakes of entangled filaments. Under such circumstances it may be differ- entiated from old colonies of Gloeotrichia echinulata by the form of the sheath, the larger size of the gonidia, and by the greater length of the flagelliform trichome. At maturity the vegetative cells dissociate, leaving the spore and the heterocyst adjoined. Common in many hard or semi-hard water lakes. Mich., Wis. Gloeotrichia Pisum (C. A. Ag.) Thuret 1875, p. 382 Pl. 134, Figs. 8-10 A firm, mucilaginous, brown or olive-green, globular or hemispher- ical colony, attached to submerged aquatics; colonies from 1 mm. to 1 cm. in diameter (usually about 5 mm.), composed of compactly [ 559 ] arranged filaments radiating from a common center and tapering from a basal heterocyst to a very fine point; colonial mucilage bounded by a leathery integument; cells short, barrel-shaped or quadrate below, becoming cylindrical in the distal portion, 4~7p in diameter, 8-12 long; heterocysts spherical or ovate, 8-11-(15), in diameter; gonidia cylindrical with broadly rounding poles, the membrane thick and sheathed, 10-15, in diameter, up to 400u long. This species is attached throughout its entire development, rarely or only incidentally becoming free-floating. In suitable hard water habitats its brown or olive globular colonies are thickly clustered and sometimes completely coat over submerged aquatics such as Potamogeton spp. and Ceratophyllum demersum. Because of the firm texture of the colonial mucilage and the compact arrangement of the filaments, the species may be confused easily with Rivularia when the plants are young, before gonidia have developed. Common in many hard or semi-hard water lakes and streams. Mich., Wis. SACCONEMA Borzi 1882, pp. 282, 298 Colonial mass amorphous or somewhat tubercular, the mucilage soft and irregularly lobed and folded, and lamellate; trichomes radiating irregularly, 2 or several within the same sheath, which is wide, lamellate, and expanded at the extremities; heterocyst and akinetes basal, the trichome tapering to fine hair-like points; plants attached to stones and other submerged substrates; one species. Sacconema rupestre Borzi 1882, pp. 282, 298 Pl. 186, Figs. 1, 2 Characteristics as described for the genus; trichomes 8-10» in diameter at the base; heterocysts globose or compressed-spheroidal; akinetes globose, 15 in diameter, with a granulose wall. On stones from a depth of 20 feet, Douglas Lake, Michigan. CLASS CHLOROBACTERIACEAE In this group of the Cyanophyta are classified minute, bacteria- like organisms of uncertain position which are weakly pigmented. The cells are spherical or bacilliform and are arranged to form amorphous, gelatinous colonies in which the cells have no definite arrangement, or the cells may form false filaments or reticulate associations. The colonies may vary greatly in size from 4-celled aggregates to gelatinous masses containing hundreds of individuals. See p. 36 in connection with chlorophyll tests involving a member of this class. [ 560 ] PELOGLOEA Lauterborn 1913, p. 99 Cells bacilliform, straight or slightly twisted, often knobby and irregular (in our specimens), solitary or in short linear series; crowded within an amorphous or irregularly globular gelatinous matrix. Pelogloea bacillifera Lauterborn 1917, p. 430 Pl. 104, Figs. 4, 5 Characteristics as described for the genus; cells bacilliform, straight or curved rods, sometimes elliptic, slightly tapering at the poles, solitary or 2-3 in linear series; densely crowded in a gela- tinous, saccate or clathrate mucilage; cells 0.6—-1.54 in diameter, 2-4, long. When this plant was collected in Scaffold Lake, Wisconsin, it was so abundant as to color the entire lake, although ordinary plankton catches failed to disclose the presence of the organism. It was found that the gelatinous colonies dissociate within the net, so that individuals or small clumps of cells only occur, these appear- ing as bacteria. Repeated collections and laboratory culture per- mitted the determination of the presence of Pelogloea bacillifera together with Plectonema nostocorum. Nannoplankter; in semi-hard water lakes; often in tychoplankton but usually found at great depths; sometimes occurring in a stratum near the bottom of a lake. Mich., Wis. [ 561 ] DIVISION RHODOPHYTA In this division the cells contain a variety of pigments, chlorophyll, phycocyanin, and phycoerythrin. The latter, a red pigment, is usually predominant, especially in the marine forms, but varying amounts of this and the other pigments produce violet, gray-green, or blue-green colors. This is especially true for the fresh-water Rhodophyta which are almost any color except red. The chromato- phore, usually axial, contains a central pyrenoid which collects starch as a food reserve. In one of the subgroups the end walls of the cells have a pore which permits intercellular cytoplasmic con- nections. The primary distinguishing characteristics of the division are the structure of the sex organs, the sexual methods of reproduction, and the types of life history entailed. Throughout the division the range of plant forms discloses an evolutionary series which has counterparts in other algal groups. There are unicellular, palmelloid, simple and branched filamentous, and frond-like expressions. In the higher forms there is often found considerable differentiation among the cells to form what might be regarded as tissues. The majority of the Rhodophyta are marine, but a few genera are either fresh-water or have representatives in inland habitats. Many of these are found in streams in alpine or subalpine situations. There are 2 subclasses, the Bangioideae and the Florideae. The former, which is the more primitive, contains 3 families in fresh water. The Florideae, a much larger group, includes the majority of species and is represented by 4 families in fresh water. CLASS RHODOPHYCEAE SUBCLASS BANGIOIDEAE In this group, the fresh-water members possess a thallus which is a branched or unbranched filament, or a ribbon-like or plate-like expanse one cell in thickness. The cell walls are thick and gelatinous and often somewhat lamellate. Unlike some of the Florideae, plants in this group do not have intercellular protoplasmic connections. The chromatophore, which is axial and stellate, contains a single pyre- noid. Pigmentation as described for the division. Asexual reproduction is by nonmotile spores. In the few known cases of sexual reproduction, divisions of the vegetative protoplast [ 562 | give rise to spermatia which fuse with vegetative cells, after which reproductive cells known as carpospores are formed. This subclass contains but a single order, the Bangiales, which is represented in our region by 2 genera. ORDER BANGIALES Characters as described for the subclass. The three families which comprise this order are the Bangiaceae, in which spores are formed by divisions of unspecialized vegetative cells, the Erythrotrichiaceae, in which spores are borne in special sporangia, and the Goniotri- chaceae, in which spores are simply modified vegetative cells formed without division of the protoplast. Only the latter family is represented in our collections. FAMILY GONIOTRICHACEAE In this family the plants are simple or branched, pseudofilamentous thalli. Reproduction occurs as described above, sexual reproduction being unknown. ASTEROCYTIS (Thwait.) Gobi 1879, p. 93 Filaments simple or branched, composed of globose or oblong cells inclosed in broad gelatinous sheaths, arranged in a more or less irregular uniseriate manner. The cells may be closely arranged, or at some distance from one another. The chloroplast is axial and stellate and contains a central, usually conspicuous pyrenoid. Asterocytis smaragdina (Reinsch) Forti 1907, p. 691 Pl. 135, Fig. 3 Characters as described for the genus; filaments simple or branched, occasionally somewhat palmeiloid, the branches develop- ing by a cell slipping to one side of the series and continuing to divide in another plane; cells 6-11 in diameter, 8-16, long. Attached to stones and to strands of coarse filamentous algae, North Trout Lake and Fishtrap Lake, Vilas County, Wisconsin; also reported (C. E. Allen correspondence) from Lake Mendota, Wis- consin. BANGIOIDEAE OF UNCERTAIN POSITION FAMILY PORPHYRIDACEAE PORPHYRIDIUM Naegeli 1849, p. 139 Unicellular but with many individuals aggregated to form an irregularly expanded, thin, gelatinous layer. Cells mostly spherical, [ 563 ] with individual gelatinous sheaths and embedded in a common gelatinous matrix; with dark red, stellate chromatophore and small, excentric nucleus. Reproduction by cell division. Forming blood-red film on moist soil and walls, especially in greenhouses. Porphyridium cruentum Naegeli 1849, p. 139 Pl. 136, Fig. 6 Characters as described for the genus. Size of cells variable: 5-9yn, 7-12, or up to 24y. On soil in greenhouse, University of Wisconsin, Madison. SUBCLASS FLORIDEAE In this advanced group of the red algae the thallus has a multi- plicity of expressions, ranging from slightly branched filaments to complex plants of macroscopic size, involving complexes of fila- ments which may be differentiated to form tissues. Growth in all these forms occurs by the activity of one or more meristematic apical cells. The sex organs, especially the female, are characteristic of the group. The carpogonium has a definite neck-like extension, the trichogyne, the shape of which varies in different genera and species and is, therefore, of taxonomic value. See Smith (1933, 1938) and Taylor (1937) for a description of morphological characteristics, methods of reproduction, and outlines of life histories. ORDER NEMALIONALES There are four fresh-water families in this order, of which three have representatives in the Wisconsin collections. The fourth family, Thoreaceae, undoubtedly is present in the plant Thorea ramosissima Bory, but as far as known this species has not been reported from the region. Sexual reproduction involves specialized female sex or- gans (carpogonia), and antheridia which develop non-motile sper- matia. In addition to gametangia, the sexual plant may produce non-motile monospores cut off from the tips of branches, especially in juvenile stages of development. FAMILY CHANTRANSIACEAE In this family the thallus is a filament which has repeated alter- nate branching and is without a conspicuous central axis. AUDOUINELLA Bory 1823, p. 340 Thallus consisting of sparingly branched filaments of cylindrical [ 564 ] cells from rhizoidal holdfasts, the branches about equal in diameter to the main filament which more or less becomes lost in the branch- ings; branches of the second and third order about equal in diameter to those of the first order; all branches ending in bluntly rounded apical cells; chromatophores discoid or plate-like bodies, without pyrenoids; color gray or violet-green; reproduction by monospores borne singly or in clusters at the ends of short branches. Sexual reproduction is known for a least one species. Members of this genus should be compared with juvenile states of Lemanea and Batrachospermum, especially if Audouinella-like plants are collected nearby, or with adult stages of other red algae. Most of the plants previously referred to species of Chantransia have been assigned to Audouinella or redefined as juvenile stages of Batrachospermum. Audouinella violacea (Kuetz.) Hamel 1925, p. 46 Pl. 135, Figs. 1, 2 Plants forming violet-green tufts from horizontal holdfast branches; filaments sparingly branched; branches scarcely tapering, varying in length from one cell to as long as the main filament; cells cylin- drical, with 2-3 plate-like chromatophores which are violet-green in color and rather metallic in appearance; filaments 8-12y in diameter. Attached in flowing water. Wis. FAMILY BATRACHOSPERMACEAE In this family the thallus has a definite axis of cells which becomes corticated by downward growing elements from node regions. Branches are given off in more or less dense and definite whorls so that a beaded effect is produced in the macroscopic appearance of the thallus. Monospores are produced at the ends of branches in juvenile stages, whereas carpogonia and clusters of antheridial cells are borne in the adult phase only. The sex organs may be monoecious or dioecious. BATRACHOSPERMUM Poth 1797, p. 36 An attached, much branched thallus consisting essentially of an axial row of large cells which cut off lateral units at definite intervals, thus determining node and internode regions; from these laterals a longitudinal investment of cortical filaments develops which more or less (depending upon the species) completely covers the axial row; also from the nodal units as well as from the cortical elements [ 565 ] themselves, out-turned fascicles of branches develop, those at the node region forming primary whorls which in many species produce a distinctly beaded appearance; cells in the axial row cylindrical, ovoid, ellipsoid, or fusiform in the branches; branching of the fasci- cles dichotomous, the ultimate branches terminating in short or long colorless hairs; entire thallus inclosed in a soft amorphous hyaline mucilage; a single massive chromatophore in each of the principal cells, and two to five disc-like or irregular chromatophores, each with a pyrenoid, in each cell of the branches; plant mass gray- or violet-green or brownish. In this genus sexual reproduction involves female (carpogonial) cells and male (antheridial) units. The latter are small, non-motile cells produced in clusters at the tips of lateral branches. The carpo- gonium is a flask-like cell with an elongate tip, the trichogyne, which receives the spermatia. The shape and location of the carpo- gonium and the form of the trichogyne are specific characters and are of taxonomic value. The trichogyne may be spatula-shaped, oblong, or lanceolate. See Kylin (1912), Sirodot (1884), and Skuja (1931) for a description of sex-organ morphology in this genus. When reproductive organs are absent, identification of species in Batrachospermum is practically impossible in most cases, and even when such organs are present, experienced judgement is often re- quired to make satisfactory determinations. Although there are more than five species of Batrachospermum in our collections, only those are listed here which have been observed in the fruiting condition. An interesting problem involving the ecology and taxo- nomy of this genus in this area awaits further studies. Batrachospermum forms dark gray-green or blue-green masses, streaming from stones or submerged wood in flowing or standing water, usually at low temperatures. Some species are less widely distributed than others and seem to be confined to acid ponds in Sphagnum bogs, where they produce growths up to 30 cm. in length on the submerged stems of Chamaedaphne or on overhanging grasses and sedges. Early in the summer, juvenile or Chantransia- stages predominate in certain habitats such as stones in flowing water. In this condition the young plants cover submerged objects with a blue-green gelatinous film. As mentioned under Audouinella above, comparison should be made between these juvenile stages of Batrachospermum and what may appear to be true Audouinella plants. Key to the Species 1. Lateral whorls of branches lacking or scarcely developed; internodes lonpesnees eee VS SE Se eee B. Dillenii 1. Lateral whorls of branches well-developed, crowded; internodes short —__ 2, [ 566 ] Peenicnoeyie clavates =... 2 eee ee 4 2. Trichogyne spatula-shaped, ellipsoid, or ovate__-—----------_--_------- 3 Sudmichogyne.spatula-shaped 2 ses eee ae B. vagum Oo einichosyne ellipsoid Or OVAte se ee ee B. Boryanum 4. Carpospores developed in outer part of a branch-whorl_______ B. ectocarpum 4, Carpospores developed in inner part of branch-whorls in axils of branchesimean the:madin axis 0". “sth eee B. moniliforme Batrachospermum Boryanum Sirodot 1884, p. 246 Pl. 136, Fig. 5 Thallus densely branched and embedded in copious mucilage, gray-green to golden-green in color; whorls conglomerate, usually closely arranged to form a decided beaded appearance; secondary branches either few or many; corticating branches many, loosely arranged; apical hairs few, slightly swollen at the base; dioecious; carpogonia on a primary lateral branch or rarely on the branches from the corticating filaments, the trichogyne ellipsoid or oval; carpo- spore masses numerous, scattered throughout the branch-whorls. Walnut Lake, Michigan. Batrachospermum Dillenii Bory 1823, p. 226 Pl. 135, Figs. 4-6 Thallus irregularly and sparingly branched, the branches rather rigid, straight or slightly curved; plant 2-5 cm. long; cortical fila- ments highly developed and inclosing the axial filament with a parenchymatous layer; lateral branching system poorly developed, the branches short with few repeated branchings, forming nodal clusters a considerable distance apart so that a jointed appearance is produced macroscopically; in the apical region the abbreviated out-turned branches numerous, compactly clustered, composed of subglobose or ovoid cells and ending in long cylindrical cells but without terminal setae; plants dioecious, the carpogonia on very short branches, produced directly from the main axis, not in whorls of branches, triangular in shape, narrowed above and then slightly inflated to form a claviform or oblong trichogyne; antheridial cells formed in transverse zones from short, out-turned branches, many occurring in ohe cluster. Scrapings from a log in flowing water. Wis. Batrachospermum ectocarpum Sirodot 1884, p. 222 Pl. 136, Fig. 4 Thallus much-branched, the whorls of branches well-developed, lobed and broadly rounded, close together, the internodes short; inclosed in copious rather firm mucilage, gray- or olive-green, up [ 567 ] to 12 cm. long; hairs few or lacking, short with bulbous bases; corticating branches few or lacking; monoecious; carpogonia on primary lateral branches in the outer part of branch-whorl, sub- tended by large cells and numerous lateral branches; trichogyne clavate. In Sphagnum bog pools; attached to stones in slowly flowing water. Mich., Wis. Batrachospermum moniliforme Roth 1800, p. 450 Pl. 136, Fig. 3 Plants stout, richly branched, with well-developed whorls of branches presenting a distinct beaded or moniliform appearance macroscopically; plant mass gray-green, violet-green, or brownish; plant masses up to 10 cm. long, forming streaming tufts (frequently in swiftly running water ); inclosed by copious, soft mucilage; plants annual; monoecious; carpogonia developed in inner part of the branch-whorls, terminal on short lateral branches in the axils, with a clavate or lageniform trichogyne; carpospore masses, dense, scat- tered throughout the plant; branches ending in long setae with a swollen base. This is the most common species of the genus in the region. It often occurs in flowing water, where it may form extensive beds on stones and gravelly bottoms. On submerged wood in streams; also in lakes. Mich., Wis. Batrachospermum vagum (Roth) C. A. Agardh 1824, p. 52 Pl. 135, Figs. 7-11 Plants freely branched, as much as 20 cm. long, forming dark olive- or gray-green arborescent masses inclosed in copious mucilage and forming soft, streaming thalli; whorls of branches well- developed, forming globose nodal masses, the branches composed of ovoid or ellipsoid-ovoid cells, ending in long hairs; the whorls quite separated in the lower part of the plant, becoming closer and coalesced distally; plants monoecious, the branch bearing the carpo- gonium consisting of 7-14 cells, developing centrally in a whorl of branches, the carpogonial cell bottle-shaped with a spatula-shaped trichogyne; antheridial units globose, few in a cluster, cut off from the tips of lateral branches; carpospores many, forming a dense mass within the center of a whorl. Attached to submerged logs in flowing water; fruiting late in summer. Mich., Wis. FAMILY LEMANEACEAE In this family the thallus is a branched, solid or hollow cylinder [ 568 J and does not show the axial plan of the Batrachospermaceae. Other essential characteristics are found in the behavior of the zygote and the method by which carpospores are formed. LEMANEA Bory 1808, p. 181; emend. C. A. Agardh 1828, p. 1 Juvenile stage composed of a branching filament, attached to rocks and other objects in swift-running fresh water; mature plant consisting of tufts of macroscopic, tubular reproductive strands which have regularly placed swellings (nodes) distributed from the tip to the basal stipe; strands generally olive-green, green, or purple, leathery, 1-40 cm. long, with nodes 0.2—2.0 mm. in diameter; antheridia produced at the nodes and carpogonia developed inter- nally, with trichogynes extending to the outside; carpospores formed within the thallus, which is hollow except for an axial filament which is either naked or closely covered with enveloping filaments; juve- nile stage maturing during winter; fruiting strands reaching their mature size in the spring and spores becoming evident in late spring. Lemanea fucina (Bory) Atkinson 1890, p. 222 Pl. 186, Fig. 7 Juvenile stage a mat or tuft 1-2 mm. high, of blue-green or green filaments; fruiting strands generally olive or yellow-green, 2-40 cm. long, with a stipe which is usually cylindric and passes abruptly into the wider portion of the strand above, strands simple or much branched, very delicate to stout, tips sometimes capillary; antheri- dial papillae and nodes either plane, or prominently raised or swollen; papillae 2-7 at each node; carpospores not developed in the internodes. Collected from Stevens Point, Wisconsin, by L. S. Cheney; speci- men in University of Wisconsin Herbarium. TUOMEYA Harvey 1858, p. 64 A macroscopic, cartilaginous and firm thallus with antler-like, dichotomous branching, brownish-green or gray-green, essentially composed of an axial row of large cells heavily invested by a mass of longitudinal, cortical filaments from which out-turned branches of ellipsoidal cells arise, thus producing a crowded pseudoparen- chymatous cortication; thallus without nodes or whorls of branches; plants monoecious, the carpogonia and antheridia developing in different regions of the same plant, the female near the meristematic apex in the main axils of the young branches. [ 569 ] Tuomeya fluviatilis Harvey 1858, p. 64 Pl. 132, Figs. 8-11 Characters as described for the genus; plant gray-green, 2-5 cm. high, cartilaginous and firm, retaining its shape when lifted from the water. Attached to logs and on the rim of a dam in swiftly flowing water. Wis. [ 570 | AN ANALYTICAL KEY TO THE GENERA Genera that are to be expected to occur in our region but have so far not been reported there are indicated by asterisks. (See also Note 2, page 92. ) 1. Plants macroscopic, 540 cm. high, growing erect from rhizoidal attaching organs and showing stem-like branches with inter- nodes and nodes from which whorls of ‘leaves’ arise (Pl. 79, Fig. 1); not inclosed in mucilage)___—_—_=———— Characeae 170 1. Plants smaller, mostly microscopic, if macroscopic and showing whorls of branches, inclosed in copious, sometimes firm, muci- | OE 2 2. Cells with pigments confined to 1 or more definite chloroplasts or chromatophores® = 3 2. Cells with pigments diffused throughout the protoplast (some- times more dense in the peripheral region ) ____--------_-----------_-___ 252, 3. Chloroplasts grass-green, chlorophyll predominating; plants form- ing starch or paramylon as a reserve food (starch-iodine test usually positive) 3) 4 (Cf. Euglena, Sphaerella, and Trentepohlia, which may have green chloroplasts masked by red pigment. ) 3. Chloroplasts or chromatophores some color other than grass- green, or with green masked by presence of other pigments; food reserve mostly oil or glycogen; carbohydrates not stained blue ype todime a ily/ (cf. the motile unicell Cryptomonas, however ) 4. Plants unicellular, solitary (See Desmids: Appendix).............0.0.0...... 5 4, Plants not solitary unicells __________-_____-________________----- 12 5. Cells motile in the vegetative state (sometimes non-motile in microscope mounts, with organs of locomotion GbSCUTE) ae 6 5. Cells non-motile in the vegetative state _________----—-—---------------__-__-- 81 6. Cells with numerous small, green, ovoid chromatophores; food reserve paramylon or oil; swimming by means of 1 or 2 long, whip-like flagella (Pl. 86, Figs. 1, 8.) aE SLL be ADs hs 172 6. Cells with 1 plate-like, cup- or star-shaped chloroplast; food re- serve starch; swimming by 2 or 4 short flagella (Pl. 1, Figs. 3, j C7 BS) eno 7 WeyBlagelle, (2,20 en SS 8 We Blage le) Ae eS 11 8. Cells ovoid to ellipsoid, with the protoplast situated at some distance within the cell wall and connected to it by radiating protoplasmic strands; chloroplast often masked by a red pig- Menit (MmAcmIALOCHTOMIC ) =.= Ee Sphaerella (in part) 8. Cells with or without a gelatinous sheath but without protoplas- mic strands connecting the protoplast to the cell wall -_--________ 9 8See Trachelomonas and Dinobryon; species are identified by shape and markings of brown or colorless empty tests or loricas. [571 ] 10. 10. . Cells round in end view; the wall simple and in 1 piece, some- times inclosed by a mucilaginous sheath ____»___ Chlamydomonas . Cells compressed when seen in end or side view; the wall bivalved and laterally extended on either side of the protoplast to form an expansion or flange, especially noticeable when seen FOIA they (SUS ee ea a aes ae ee 10 Cells lenticular or elliptical in side view; valves of wall, when viewed from the side, apparent in the vegetative condition; cells often rectangular in front view, with horn-like processes at the-angless? Shed see eee ee ed * Phacotus Cells ovate in side view; the valves of the wall evident only during cell division or release of swarmers; cells circular or OVOIGMI ATONE Vie Wis neat es EEE TL en ee nk eee a Se * Pteromonas . Cells elliptical, ovoid, or somewhat heart-shaped, with 4 flagella arising from the midregion of the anterior end Carteria . Cells ovoid in front view, quadrate in end view, with 4 rounded lobes; flagella 4, each attached in a depression of the anterior Ti Cl See ee rrp I el tle et 2h Re NET Nl eA PES TT Pyramimonas . Plant a motile colony; cells inclosed by colonial mucilage; swim- ming bysmicanston2)or4. tape lla eee See eee eee 13 . Plant non-motile in the vegetative condition; filamentous, or con- sisting of a definitely or indefinitely formed colony or aggregate of cells. (See. Desmids:)-Appendix)= 2 3 eee eee 20 . Colony composed of cells arranged to form a flat or twisted plate 14 » Colony*spherical. spheroidal "or, ovoid = = 15 > Colonysa’ circularjon rectangularplate == eens Gonium . Colony an ovoid or horseshoe-shaped plate, broadly rounded anteriorly, truncate posteriorly, with 3 prominent projections of thecolontal/investment\s = eee ee Sees *Platydorina . Colony oblong, without a gelatinous investment; cells pyriform, all directed toward the anterior end of the colony; flagella 4._Spondylomorum . Colony ovoid or spherical, with a gelatinous investment; flagella 2_____ 16 . Cells with sharply pointed lateral extensions of the protoplast, arranged to form a mediaa girdle within a spheroidal colonial Shea thy cnet AE RS ER EU he noe Ee ee Stephanosphaera «Cells: not arranged as ‘above 2s) 2 sie a oe eee 17 . Cells pyriform, broadest at the anterior end, compactly arranged in ovoidor ellipsoidal colonies 25s eS Pandorina . Cells ovoid or spheroidal, not compactly arranged within the colonial. mucilage, colonies’ globular or ovoid == === = _ 18 18. Colony spherical, involving hundreds of cells (500 to 5000 in- dividuals ); all the vegetative cells the same size and sometimes interconnected by protoplasmic strands _..____________-_--___--------------- Volvux 18. Colony spherical or obovoid, involving but a few cells (usually 32-64, rarely up to 256), without intercellular connections — 19 19. Colony spherical, containing cells of 2 sizes which are evenly dis- tributed at the periphery of the colonial mucilage — Pleodorina 19. Colony obovoid or spheroidal, containing cells all the same size aad often. arrangedian fers") a Eudorina 20. Plant a pair of trapezoidal cells adjoined along their bases Euastropsis 20. Cells otherwise arranged, or of different shape —______-_--------------------------- 21 [ 572 ] VAL 21. 22. 22. 23. 23. 24. 24, 25. 25. 26. 26. 27. 27. 28. 28. 29. 29. 380. 80. 31. Plant a definite colony or an aggregate of individuals either ad- joined or lying free from one another, sometimes invested by mucilage_...22 Plant a branched or unbranched filament, either a series of cells, or a tubular coenocyte (without cross walls), or filaments form- ing an’ attached, cushion-like thalhus= = 116 Colony of cells invested by a common mucilaginous sheath, or gelatinous matrix, (often close and discerned with difficulty; SECT DICE OSTIINICTILLIN) oc eee 23 Colony or aggregate of cells not invested by a common muci- [emuaris)s hep ae eae AT Colony attached. or adherent to'a substrate 24 Colony free-floating (sometimes entangled among other algae, butenoteattachedestovtlae rns) assess aie te eer eee eee 31 Colony saccate, bullate, intestiniform (Pl. 5, Figs. 1, 3), Or cushion-like when growing on moist substrates (Pl. 3, Figs. 8, 9); Tis llyennacKOs Cop ice ae en eS 25 Colony shaped differently; microscopic ____________-___________ 26 Cells in 2’s and 4’s, bearing long, fine pseudocilia (PI. 5, Figs. 6, 11) which extend far beyond the limits of the colonial muci- lagessplants; aquatic = Tetraspora (in part) Cells without pseudocilia; plants mostly aerial, living on moist SUIS CERCA es al Palmella (in part) Colony pyriform, narrowed to form a stipe-like basal attaching portion; cells arranged at the periphery of the colonial mucilage (ottentshowimp long, pseudocilia) = Apiocystis Colony shaped differently; without pseudocilia She Pas eae SE 27 Colony fusiform; cells fusiform (Pl. 4, Figs. 1,2), solitary or in linear pairs within the colonial mucilage and arranged with their long axes parallel; colony usually free-floating but may be at- PACHECAWHEM YOUNG. Elakatothrix (in part) Cells not fusiform and not contained in a fusiform sheath —___----- 28 Cells elliptical or subspherical, arranged in 2’s and 4’s within ungelatinized walls of mother cell; many cells inclosed by a common mucilaginous investment; a red pigment spot and an apical papilla often visible —__-- Palmella stage of Chlamydomonas Cells spherical or ovoid, scattered irregularly throughout the colonial mucilage, not inclosed within walls of old mother cells; pigment spot lacking —____.__-____---------= === == 29 Colony composed of cells inclosed in shapeless masses of muci- lage, with individual cell sheaths confluent with the common gelatine .. 30 Colony irregular, but keeping a definite shape; cell sheaths not confluent with the colonial mucilage, but definite and often lamellate (Pl. 3, Fig. 17); plants aquatic or growing on moist soil, but becoming red in some species when exposed to strong ALITA EO Tee we ee eg a Je Oe Gloeocystis (in part) [ 573 ] 31. 32. 32. 33. 383. 34. 42. 42. Coloniestshaped differently from above=._ See 82 Fragments of old mother cell walls lying scattered about and partly inclosing spherical daughter cells; colonial mass soft and shapeless, usually floating at the surface__________________ Schizochlamys Fragments of old mother cell walls lacking or, if present, not scattered among daughter cells; colonial mass of definite shape____ 83 Colonies irregularly globose or spherical; cells arranged in groups of 4, the clusters remote from one another within copious muci- lage; cells bearing long pseudocilia (visible only under favor- able optical conditions))h == = ee eee Tetraspora (in part) Colonies of various shapes; cells not arranged in groups of 4, and! without pseudocilia 2-0 0c 2 03” Ee ee ee ak 34 Cells ovoid, compactly arranged in semi-opaque mucilage, form- ing dense, simple or compound masses, adhering to one another by branching strands of mucilage (Pl. 52, Figs. 1, 2); individual cells often not apparent in older colonies because of dark muci- lage and density) of cell contents. Botryococcus (in part) . Cells not arranged in semi-opaque, irregularly shaped colonies... 35 . Chloroplast a stellate mass with radiating processes. Asterococcus (in part) si Chloroplast, not)stellate ss ee. mia bate oe eV ey 5 ate EST se ee 36 . Cells arranged in groups of 4 at the ends of branching strands formed by the remains of old mother cell walls; colony ovoid OLE IG DOSe PENAL Sai Ae Pied Slt lined Caan SEEPS ES Sie etd eee 87 . Cells not arranged at the ends of branching strands; colony of VAnLOUSS SHADES 22 see ce SE he Oe Es ee ee ee 88 . Cells reniform to sausage-shaped and some also appearing ellip- soid in each group of 4, at the ends of branching strands (gela- tinous investment usually lacking)... Dimorphococcus (in part) . Cells spherical or broadly ovoid, all the same shape, in groups of 4 at the ends of branching strands____________________________ Dictyosphaerium b Gells ssylneri cal = aks ee a ee a 39 . Cells of various shapes, fusiform, ovoid, reniform _____---------------- 42 . Cells arranged in linear series (single or double) within branched gelatinous strands; either with or without individual lamellate sheaths ea seees out os Be eRe ne aE eS, Palmodictyon (in part) t Gells\ arranged! otherwise... ee ee ee . Colonies spherical or irregularly shaped, sometimes triangular, with cell sheaths distinct and not confluent with the colonial IMC ape eae mee seu _ .. .... Gloeocystis (in part) . Colonies spherical; cells without individual sheaths, or with sheaths confluent with the colonial mucilage and not apparent ____---- 4] . Cells with cup-shaped chloroplasts containing a conspicuous pyrenoid; colony usually showing daughter colonies of smaller cells resulting. from cell division. = 2) Sphaerocystis . Cells with several peripheral, polygonal chloroplasts, each with a pyrenoid (when cells are young with but 1 cup-shaped chloro- plast; in this condition to be compared with Sphaerocystis ); colonies never containing daughter colonies, but frequently dis- integrating so that cells become solitary______ Planktosphaeria (in part ) Cells lunate or sickle-shaped, with narrow poles —_____--------------------—-- 43 Cells reniform or fusiform, with rounded apices -_.....---_------------------- 44 [574] 43. Cells strongly curved so that the poles nearly touch, scattered throughout the colonial mucilage in groups of 4, generally with the convexs walls} (apposed i) ss 9 sy Kirchneriella . Cells crescent-shaped, arranged in groups of 4, 2 of which are in one plane facing each other, and 2 at right angles to this plane, each of the latter adjoined to one pole of the cells in theyothers pair’ 25. 5. + stars, hehe gd eee iiaaa lies ie Tetrallantos (in part) peC@el sehen eh corer 02) A OE. cee ee en Oded Meee TEN oll 46 u@ellstovates seniors oroblong = 2 we ane mented) eee Wen ih 45 . Cells ovate, arranged in 4’s within a gelatinous sheath, forming Anite bap labceen eee WW sn it hub iS Ge DE aReR ee rene 6 ORS MOTE UF A Dispora . Cells reniform or oblong, reproducing by autospores usually re- tained within the old mother cell wall which may gelatinize and appear as a mucilaginous sheath... Nephrocytium (in part) . Cells solitary or in linear pairs within a fusiform, gelatinous enve- lope, multiplying by cell division. Elakatothrix (in part) . Cells arranged in parallel bundles of 4, reproducing by auto- NSE ONES. Quadrigula SPOTFeEs: _-2-_________- . Cells, or some of them, in clusters, bearing gelatinous bristles OLE SCtAG a ee ce ee ee ee Ee Te Ce en cat On eNom bell ln eco Seine EID |. 48 . Cells not bearing gelatinous bristles with or without spines................ 49 . Cells compactly arranged to form an adherent, dome-shaped cluster within the old mother cell wall which bears a dichoto- mously branched seta. (This cluster of cells results from the formation of zoospores and not from division to form successive generations of vegetative cells.) Dicranochaete (in part) 48. Cells globose, epiphytic, loosely arranged side by side to form a cluster (often solitary however), each bearing a sheathed, un- branchedwseta+@ Mose! : Pe Ue AUT 5s Chaetosphaeridium (in part) 49. Cells attached at the ends of branching gelatinous stalks, epizoic OUEMICTOSCOMiG. AuIMIaIS seca ue Oe 1. ES ee en ed 8 50 400 Gelis not so,atanged ;not.epizoie == ee te ei ee a 51 50. Cells ellipsoid or spindle-shaped, chloroplasts 1 or 2 parietal | SEPT STG KS Li AE hint Lae ee SE SAL ere Ft 0 ig ene Chlorangium (in part) 50. Cells ovate or oblong, with numerous disc-like chromatophores (sometimes referred to as chloroplasts)... Colacium (in part) 51. Cells broadly fusiform or elliptic, attached end to end to form lodsessbranching chains. 5) 27 2 Cea a Dactylococcus (in part) ey bral@ells mots SO arramG ees: Loker cee a Mee Mine ee eR 52 52. Cells globose or angular from mutual compression; aerial; forming elumps on moist substrates 22 Protococcus (in part) 52. Cells differently shaped, not forming expansions on moist substrates —__.. 53 53> Cells acienlar or stiehtly lumate = ves ee 54 So, celisiiditrerently. shaped = =) See ley 2 eh el at 55 54. Cells strongly curved, arcuate or lunate, not entangled but closely aggregated in families of crescent-shaped individuals Selenastrum . Cells straight or_slightly crescent-shaped, loosely entangled or twisted about one another; often solitary. Ankistrodesmus (in part) . Cells adjoined by their lateral or end walls to form definite pat- EernsxOr akrangements = ts ius eee ed 2 ee 56 . Cells grouped otherwise, not adjoined by their lateral walls or, itso; notstonming ‘definite patterns =. sates Be oe he 71 [ 575 ] . Cells cylindrical, adjoined at each end by 2 other similar cells :in successive order to form a network of coenocytic units, the meshes ofiwhichware?D= Or G-sid ed) 125-040 erie See Hydrodictyon . Cells attached by their lateral walls, or clustered to form other by pes ok ce neg a an ee ee ee eee 57 . Cells forming flat, circular or rectangular plates______»_ 58 Cellsmnotiorming flat plates! 2) sxx5te See eee 61 . Cells forming circular or subcircular plates which may be per- forate or continuous; marginal cells with a deep or shallow incision or sinus; cells within the plate usually somewhat different in?shape from) those atthe margin Pediastrum » Cells not arranged’ to: formucireular plates! ee ee 59 . Cells triangular or ovoid, the walls bearing 1 or more spines, LOrming quadrate plates of 4 cells cache = 2 ee Tetrastrum 2 Gellsiio& bearing splices 220 Sa a ee te 2 60 . Cells rectangular or trapezoidal, the outer free walls smooth and entire, cruciately arranged to form quadrate plates of 4 cells or TiUtiplesN OL Ai stde tee ES 2k AUS ee ek Sena ee Crucigenia . Cells trapezoidal, the outer free walls deeply incised, cruciately arranged to form subquadrate plates of 4 or 8 Pediastrum tetras . Cells bearing: spines: 2: Sethe 2 ee 62 : Gells without. spinest= 2 2). Sa ee 65 . Cells ellipsoid, bearing many needle-like spines, adjoined side by side to form clusters of indefinite number (usually 2 to 8), some- HINES :SOlitan yo tleAe ec Oe ee ak eS) Franceia (in part) . Cells with few spines (1 to 4, rarely as many as 7); cells defi- mittely darrian cece 6 ps Os ce ee 63 . Cells ovoid, adjoined side by side, forming a linear series (single or double ); spines usually few in number and mostly confined to the poles of the cells or with 1 or 2 on the lateral free walls (many minute spines in Scenedesmus hystrix) Scenedesmus (in part) . Cells spherical, arranged in groups of 4 and multiples of 4 to form compound colonies; outer free walls bearing 1-7 very long BEM eT SOLS rena ete ee 64 . Compound colony triangular in outline; spines 1 to 7 in num- | oY =i ems. ie PO SEN SS WARES Tee inte ely AIR ete a Fae ET fe Bl ae Micractinium . Compound colony always pyramidal in shape, outer free wall of cells bearing a single, stout long spine _________. *Errerella bornhemiensis . Cells spherical or trapezoidal, arranged to form hollow, spherical, or polyhedral colonies, the cells adjoined by interconnecting protuberances 228 22s ee eee Coelastrum ; ells not arranged in hollow colonics == ee 66 . Colony composed of narrowly fusiform cells radiating from a common center where they are adjoined at their poles —______ Actinastrum . Colony not composed of fusiform cells radiating from a common Ceriter esc sha Oe Is eR ee we 8s) Ee a ee 67 . Cells elliptical or fusiform, attached end to end to form branch- mip, chain-like series. +s Sos ee Dactylococcus (in part ) . Geélls not forming such branching chains 2222 = 68 . Cells ovoid, elliptical, or fusiform, adjoined by their lateral walls to form a series of 4 or more cells lying side by side in one plane.(rarely im a icurved plate) <3 Scenedesmus (in part) [ 576 ] . Cells round or, if shaped otherwise, not attached side by side id OMG yl avis men ome ae e/a 5hc And Re Ree eke A a | 69 . Cells fusiform or trapezoidal in face view, adjoined by their inner faces in groups of 4 about a common center; long axes of the COE) VIS) a || a se re, re Tetradesmus . Cells differently shaped, not attached about a common center___._____ 70 . Cells lunate or crescent-shaped, arranged in groups of 4, two cells in one plane, and two in a plane vertical to the other pair (Pl. 66, Figs. 4,5), one pole of each of the latter pair adjoined to a pole of the cells in the former; cells usually inclosed HTIBIMUCTIAD OW tie Set e $ 25 Lo ty A A oe Tetrallantos (in part) . Cells fusiform or needle-shaped, twisted about one another to form a definitely shaped knot of individuals, or a somewhat ir- Regma Cluster a ns. ee Ankistrodesmus (in part) 71. Cells held together by fragments of mother cell walls of previous generation (Pl. 53, Fig. 14; Pl. 55, Fig. 8) Pea eins) See yh? 71. Cells not held together by fragments of mother cell walls. 73 72. Cells spherical, arranged in groups of 4 or 8, fragments of older 78. 78. mother cell walls forming loops which help to hold the groups, cormnarant tip leseolontes =e smu he ot Westella . Cells both ovoid and reniform, in groups of 4, arranged at the ends of branching strands formed by old mother Gell weallllsseane sree bt a eee a De ee a Dimorphococcus (in part) . Cells pyriform, semi-lunate, or reniform, bearing spines on their outer faces, each cell at the end of a short, thick, gelatinous stalk which radiates from a common center where it adjoins stalks of otherucelis im the colomy s. 20s we ea Sorastrum . Cells of different shapes, not arranged as above... 74 . Cells spherical or broadly elliptic, closely arranged in 2’s and 4’s within the old mother cell wall, the cells separated from one another by semi-opaque masses of mucilage, sometimes with a plug of dark mucilage in the outer free wall of Cachicelle aes Sle ce 2 Lee aes 8 Pe 208 Gloeotaenium (in part) . Cells of different shapes, not separated by dark bands of mucilage_____ (a3 . Cells spherical, bearing spines; loose and temporary clusters formediiby entangling iof spines 26. =. 3.) Sate Golenkinia (in part) 2) Cellsenots bearing (spines teas Scie i aie Se 5 Te 76 m@ellstmclosed by old, mother cellwalls! a et if ; Cells not-inclosed’ by’old mother’ cellwalls 2 2). 4 78 . Cells reniform or broadly elliptic, inclosed by old mother cell walls (often gelatinized, thin, and appearing as a mucilaginous Shea thy) ete aT Pe Shr ee nh wh LRP ate Nephrocytium (in part) . Cells elliptic, moniliform, with nodules at the poles in some species, or subcylindrical, or panduriform (retuse lateral margins); old mother cell wall much expanded, S@mietimes ela tinizim sce mein eS aL ee es Oocystis (in part) Cells spherical, with several polygonal chloroplasts; arranged in spherical clumps or distributed throughout the gelatinous enve- lope (which is sometimes wanting, or TUbMap parent) eeeee-. show Memuaes ee SA oe Sh Planktosphaeria (in part) Cells more loosely arranged, sometimes solitary; chloroplasts EIQ E pO Yeo ed ee oan eee Re ene efor ste Pe ae oe 98 ST) 79 . Cells spherical, not bearing spines; subaerial or terrestrial, some- tameseregarious: and densely clustered == emeeenens eee 80 . Cells aquatic, fusiform, acicular or needle-like, loosely clustered OTA TLAN CEC et es tn esha aU ea Oe eee eee Ankistrodesmus (in part) . Cells gregarious (although sometimes solitary), but not adjoined, usually in several-celled clusters on damp soil or moist sub- strates; chloroplast not lobed = sesame Chlorococcum (in part) . Cells in dense clumps and adjoined, rarely solitary; spherical, or angular from mutual compression; chloroplast a dense, lobed plate early filling: the cell = Protococcus (in part) (Pleurococcus ) & Cells tbearingspmes Or Sete ea = «. sash einen ter tUR ee ee Lae eo 82 aw Celis#wathorit ys pimesiOr Setae 2 si: wanetens sate sree ee een teed eevee Cae eae 93 . Cells bearing a simple, sheathed seta___________. Chaetosphaeridium (in part) -/Cellsinot bearing arsbeathed! seta 2-2) Sass ee ee 88 . Cells bearing a single dichotomously branched sar 20 soe /eteee hee a fy Ca Se Dicranochaete (in part) . Cells not bearing a dichotomously branched hair____________________________ 84 . Cells ellipsoid or ovate, bearing 1 to 4 teeth or short spines, mostly at the poles; cells usually attached side by side, but sometimes: solitan= ne ein ns Scenedesmus (in part) . Cells fusiform or some other shape than above or, if ellipsoid, bearing long spines over the entire surface of the wall .._-_-_-__»____- 85 . Cells triangular, pyramidal, quadrangular, or polygonal _______»____ 86 “ Cellsvovate round fusitorm.ior acicular2 = a" ses eee eee 88 . Cells pyramidate or tetragonal (rarely pentagonal), with 4 to 6 fine, needle-like spines radiating from each angle (see, however, Rolyedtiopsisn. quadrispina) = eno: Sa ee Polyedriopsis . Cells pyramidate or polyhedral, without a tuft of needle-like spines ‘at eachmangle situ sas hn es SE a ee eS 87 . Cells triangular, polygonal, or pyramidal, consisting of a definite body with 3 short, stout spines at the angles or at the apices OP MprOCesses es sates fil t ENG. SO WO ae Tetraédron (in part) . Cells pyramidal, each angle extended into a long spine-like pro- cess, the body of the cell small in diameter and not distinguish- able trom) the ‘basesiof thes processes 25 0s. sas sae) Pee Treubaria . Cells acicular or fusiform, the poles extended to form a long, finely-pointed seta, one of which may fork at the tip and serve as jan: attaching: organs see soe alm Eola ha ee Schroederia , (Gals sete aroronllere Gye aarcinioynin 89 » Cellsiglobose; with radiating spnes= = 90 » Cells wovatéewon,jellipticalle*s.25)) Je) eee 92 . The entire wall beset with long, stout, tapering spines which ANC ADEOAGWAtEthiC bac pes e eee eae ie eam ce eee Echinosphaerella . Cells bearing needle-like, slender spines________________________- 91 . Spines needle-like throughout, gradually tapering to a Tne) 2) 0 OLE Ras Aaa a eM ENCES Bie Si Sh ene OLN Golenkinia (in part) . Spines with basal portion thickened, then tapering abruptly to a, longs inely,. pointed | tip, 3.8 gaa te ses Acanthosphaera . Cells elliptical, with fine, needle-like spines arising from all pantsyofsthes wall wlie 2 aan her Cd Bev ieee Franceia (in part) . Cells ovate or ellipsoid, with a few long spines at the poles or localized at. both poles and equator. = =o ee Lagerheimia [ 578 ] 93. 93. 94. 94. 95. 9a: 96. 96. Sle ile 98. 98. 99. 99: 100. 100. 101. 101. 102. 102. 103. 103. 104. 104. 105. 105. 106. 106. 107. 107. Cells irregularly globose or ovate, endophytic, buried within the tissues of higher aquatic plants. Chlorochytrium Cellsenotiendo phytic = ena ee 94 Cells endozoic, inhabiting the tissues of sponges, Hydra, and I0L0 202 ee Zoochlorella Wel stretch ZG ee 95 Cells epizoic, attached to small crustaceans such as Cladocera and copepods 8 96 Cells not epizoie _.98 Cells fusiform or acicular, with a single diffuse chloroplast; attached by avslender stipe = Characium (in part) Cells ovate or elliptic; chloroplast not a diffused sheet; attached by a thick stalk 97 Cells with 1 or 2 laminate, elongate chloroplasts Chlorangium (in part) Cells with many ovate, disc-like chloroplasts (usually in branched colonies. sometimes, solitary )— == Colacium (in part) Cells free-living, not epiphytic or endophytic -__________________-- 100 Cells epiphytic ———_----—--——---------—-— 99 Cells globose, gregarious, attached by the anterior end, which is elongated to form a narrow stipe; with a massive chloroplast in the upper (posterior) end of the cell; growing in the mucilage of blue-green algae_._________________------—--------------__------- Stylosphaeridium Cells fusiform or cylindrical, attached to filamentous algae or higher aquatic plants ______---------------________---- Characium (in part) Cells fusiform to acicular, much longer than their diameter_— 101 Cells not spindle-shaped but of various other forms: spherical, ovate, oblong, pyramidal, or polygonal _____-_-__________-----_---- 102 Cells narrowly fusiform, 3-6y in diameter, 50 (or more) times longer than wide ._________-__-_----------------------- Closteriopsis Cells much smaller than above, length less than 25 times the GATING LET eee en ER, | er inte ae et eae Ankistrodesmus (in part) Cells spherical, inclosed in a wide, spindle-shaped, 2-part enve- lope (the parts adjoined at the equatorial plane). Desmatractum Cells not inclosed in a spindle-shaped envelope -—---__----------~ 103 Cells spherical, wall decorated with a reticulum of ridges which form blunt or sharply pointed projections at the periphery Trochiscia Cells variously shaped; if spherical, without a Teticulum: | ee 104 Cells broadly and irregularly ellipsoid or subspherical, with thick uneven stratiiied, walls Excentrosphaera Cells spherical or of other shapes, without thick stratified walls. 105 Gells spherical 106 Cells not spherical iis Cells containing a single axial, stellate chloroplast with radiating processes which become flattened at the periphery Felice) | ee ee ae eens oe ee Asterococcus (in part) Cells not containing a stellate chloroplast) = = 107 Cells large (50-300» in diameter ), globular, containing numer- ous ovate or disc-like chloroplasts arranged in radiating cyto- plasmic strands and in a layer about the wall; chloroplasts shifting their position in response to light intensity Eremosphaera Cells smaller, without numerous ovate chloroplasts Rete: 108 [ 579 J 108. 108. 109. 109. 110. 110. JO ul ts 112. 112. 113. 113. 114. 114. 115. 115. 116. 116. 1a Uele IBGE 118. 118. Cells inclosed by a gelatinous sheath, with a parietal chloroplast that nearly covers the wall (plant usually colonial but sometimes occuring as asingle cell). => ee Gloeocystis (in part) Gells notimclosed by . seen ste ses ere: ee *Gonyaulax . Cells with 2 antapical plates, slightly flattened dorsiventrally_ Peridinium . Colony actively swimming by means of flagella ___.._.___.-__._.-_-_.--.... 248 . Colony non-motile, or cells with rhizopodal processes __.___----- 247 . Cells 2, or 4-8, irregularly arranged in a common mucilage_....Chrysocapsa . Cells 16 (rarely 32) radially arranged in a wide gela- tinous sheath which is heavily impregnated with granular Waste | PrOGUCES oul med 9 ies ye oe ew trey a2 Chrysostephanosphaera . Colony spherical, composed of ovoid or pyriform cells arranged ab thes penphery of a colomalmucilage 26 ee eee eee 249 . Plant not a spherical colony of ovoid or pyriform cells —__...-- 251 . Cells each with 2 apical cylindrical receptacles from which a longesiliciouswnodvextends/.05 Samar. ese kee ee ee ees Chrysosphaerella iiGells* not ibearing? silicious, 10ds'= 2 = eee 250 . Cells elongate-ellipsoid, or elongate-pyriform, with silicious scales in the apical region; swimming by 2 flagella of equal length Synura . Cells small,ovoid or pyriform, without apical silicious scales; flagellac2qunequal imilength! 2222.2 2 eee Uroglenopsis . Cells amoeboid, without loricas, adjoined in loose linear series by thenslong-tthin, pseudopodia 8) ee Chrysidiastrum . Cells with vase-shaped or conical loricas, forming arbuscular or diverging colonies, with 1 or 2 loricas emerging from the mouth of the lorica* below... ees SS eee Dinobryon (in part) . Plant an attached parenchymatous mass in which filamentous arrangement of cells is not clearly evident; endospores formed in the upper or outer cells of the plant mass, or of the branches__.*Pleurocapsa . Plants otherwise, not a parenchymatous mass .______------------------------- 253 . Plants unicellular or colonial, usually with an evident sheath, Which mayebesiamellated 2 ee ee 954 . Plants filamentous; cells arranged in 1 or more series and in- closed or not inclosed by a sheath (Pl. 112, Figs. 1-8). (The series of cells is termed a trichome and this, together with its sheath, is called a filament in this group of the algae.) 274 [ 590 J 254. 254, 255. 255. 256. 256. 257. 257. 258. 258. 259. 259. 260. 260. 261. 261. 262. 262. 263. 263. 264. 264, 265. 265. 266. Plant a spirally twisted, long or short unicell, usually showing Oseillatme@Or-spiral movements #22. Spirulina (in part) ear tO ter WV iSe ees a see me ee ES Ss 255 Plant an epiphyte, a sheathed, club-shaped unicell usually show- ing endospores (Pl. 108, Figs. 5, 6), which are cut off success- ively from the apex of the protoplast _____________________. Chamaesiphon Plant solitary or colonial, not forming endospores; not a club- Shiga (iitte 2) | 256 Cells embedded in a mucilaginous sheath which may be lamellate__. 262 Cells not embedded in a common mucilaginous or gelatinous matrix___.257 Celisigio bases SS SS 258 Cells longer than wide, oblong or cylindrical ___________________. 259 Cells minute, 1-5 in diameter, solitary or gregarious (usually with a sheath, but this is often not apparent)____ Chroococcus (in part) Cells larger, up to 504 in diameter (colorless host cells with vermiform, endophytic blue-green protoplasts )_______ Glaucocystis (in part) Cells solitary or sometimes in families of 2-4; oblong or broadly ovate to subcylindrical, up to 504 in diameter —___________-_____ 261 Cells in small colonies or rarely solitary, cylindrical, strongly Canved! or pyriorn == 260 Cells in small clusters, sometimes solitary, strongly curved, de- scribing nearly a complete circle, sometimes lying with long axes parallel in compact series within the mucilage of other algae __Cyanarcus Cells pyriform, radiately arranged in small colonies and inclosed by an inconspicuous gelatinous investment, which is invisible dinless stained se ie Su en Se ee Marssoniella Cells ovate, solitary or in families of 2 to 4, inclosed by old mother cell wall (colorless host cell with endophytic blue-green protoplasts), up to 504 in diameter______________ Glaucocystis (in part) Cells oblong or subcylindrical, up to 15y in diameter, not sym- | US aUSR AES 51 0 Oh Gene Re is Swe el a ee Synechococcus Cells globose, 2-16 in a mucilaginous sheath in which individual cell sheaths are visible; free-floating or adherent, sometimes Rats enlace ee eee pee ne eee ee Chroococcus (in part) Cells globose, cylindrical, or elongate, forming many-celled colonial aggregates of more than 16 individuals, inclosed by copious mucilage which may or may not be lamellated —_________. 263 Cells 10 or more times their diameter in length, cylindrical, Ret ORTH) OR PusifO ria se ee eee 264 Cells 2 or 3 (rarely as much as 8) times their diameter in length; round, ovate, or short cylindric —-—______________------------- 265 Cells narrowly fusiform, with tapering, blunt-pointed Sie ee Dactylococcopsis Cells reniform or vermiform, straight or variously curved__. Rhabdoderma Cells minute, 0.61.5 in diameter, bacilliform, crowded within a colorless colonial mucilage; pigment scarcely discernible... Pelogloea Cells larger, or not bacilliform; pigment readily discernible 266 Cells oblong or short cylindric, with poles rounded, crowded and irregularly arranged in copious mucilage; individual cell sheathsisometimes evident = ( Anacystis, in part ) Including: a. Aphanothece, with individual cell sheaths not apparent; b. Gloeothece, with individual cell sheaths apparent. [ 591 ] 280. . Cells spherical or ovate, sometimes elliptical; not cylindrical, but/very dlittle longer than “wide =. 267 . Cells round, embedded in copious mucilage with concentric lamellations; individual cell sheaths becoming confluent; plant usually formed by large numbers of cells; occurring mostly in aerial ‘habitats, sometimes aquatic 2 Gloeocapsa . Cells of different shapes, ovate, ellipsoid, or, if spherical, not forming shapeless gelatinous masses on moist substrates ——_________ 268 . Cells round, ovate, dividing in 2 planes only to form flat, usually rectangular, plates, with margins of plates sometimes rolled —________ 269 . Cells dividing in 3 planes to form spherical, ovate, or amor- POUS Vass ES ol es Se as ee ee 270 . Cells regularly arranged in rectilinear series forming rectan- Sulaky plates ita 1 a1. Toe Se A ee ae Merismopedia . Cells irregularly arranged in 2’s and 4’s but not in rectilinear SCTIES ses MTSE BLE ek Re RL aC ore PA EE Holopedium . Colony hollow, the cells arranged in one layer near the periphery. 271 . Colony not hollow, the cells distributed throughout the colonial TIRLIC Wag © oe obo eros wee eee eee ee ee 272 . Cells at the ends of branching, gelatinous strands which radiate from the center of the colony (sometimes scarcely visible) Gomphosphaeria . Colonies without radiating gelatinous strands ——________ Coelosphaerium . Cells longer than wide, distributed throughout the colonial muci- lage, with or without individual cell sheaths apparent. ( Anacystis, in part ) Including: a. Aphanothece, with individual cell sheaths not apparent; b. Gloeothece, with individual cell sheaths apparent. Be Ce llsip clo logs cts eet nete ean 273 . Cells crowded, usually very dense, not evenly distributed within the colonial mucilage; pseudovacuoles present or absent (PI. 1) 2egiti 0, ly) eee ren ce Seber eee ee Microcystis ( Polycystis ) . Cells evenly and relatively remotely spaced throughout the colonial mucilage; cell contents granular or homogeneous, with- Outs pscud Ovactiolcsmes. = @es- ten es Aphanocapsa . Heterocysts present, although sometimes infrequent —.________ 290 . Heterocysts not present; trichome with or without a sheath, sometimes more than 1 trichome within a sheath ......________-- 25 } Umichomespspirallyscoiled <=. 276 . Trichomes straight, bent, or entangled, but not regularly coiled 422 278 , TGR nemnes Wriin a Caenin Lyngbya (in part) Dutra chonie se WwitnOUcray Siacathcesete. ee ees oe os ee ee ee 277 . Plant a 1-celled trichome, up to 3004 long Spirulina (in part) . Plant a many-celled trichome, the cross walls indistinct; usually muchwongenthanla poves ss = Arthrospira . Trichomes aggregated, tapering to a point from an attached basal prostrate: cushion oficells= == Amphithrix (in part) . Trichomes not tapered, or if tapered, without a basal prostrate GUS HIOM La Cell smn tera ee ee en ia See ee ee ne ee 279 . Trichomes without a sheath (though hormogonia may show aeithiiy Seeat ins) Meee ames ett eT heh ee ee es ee Oscillatoria . Trichomes with a sheath which is usually very definite 280 . Trichomes tapering from base to apex, often ending in a Frat en 281 Trichomes not tapering, the same diameter throughout their length 282 [ 592 ] . Trichomes gregarious, apices extended; plants parallel in a Ceol STEN Fi CM ir 2s) ews oS abe Amphithrix (in part) . Trichomes diverging; plants not parallel_______________- Calothrix (in part) . Trichomes with false branching (branches sometimes infre- CGH) eee eee ee eS Plectonema ME raichormes emo t. brane lie Ce a ee 283 . Sheath containing a single trichome_____—_______-______________ 284 . Sheath containing more than 1 trichome —__——___________________. 287 . Sheath firm and definite, not adherent to sheaths of other plants andi not comhuent fee Lyngbya (in part) . Sheaths mucous and sticky, confluent with sheaths of other plants (sometimes individual sheaths indistinct unless stained ) 285 . Trichomes lying parallel, forming planktonic fascicles. *Trichodesmium . Trichomes not forming planktonic fascicles; sheaths mucous EATNGE GL PETA UT Ua tesa ce ede We, en ee eee ee nes eee ee 286 . Trichomes much entangled (sometimes parallel), forming mucous plant masses and often thick layers on substrates; sheaths watery (best demonstrated with chlor-zinc-iodide reagent—see Drouct..19a1.(p) 604) = Phormidium . Plant mass forming erect tufts from an expanse on a substrate; sheaths usually firm; plants mostly terrestrial _________ Symploca . Sheaths firm, usually branching at the ends ____________________________ 288 . Sheaths wide, mucous, soft and sticky, dividing and frequently anastomosing at the ends ____________--_---------_-----------___-- 289 . Sheath wide; trichomes few and separate, not intertwined. *Dasygloea . Sheath close, trichomes many, intertwined. Schizothrix . Trichomes loosely arranged, 2 to 4 in a sheath —_____ Hydrocoleum . Trichomes densely entangled, many within a sheath Microcoleus . Trichomes decidedly tapering from base to apex 291 . Trichomes not tapering from base to apex —----------------_---------— 295 . Filaments inclosed within a copious mucilage, many united to form a globose or hemispherical attached or free-floating thal- lus of macroscopic size ———___________-_-______-______— 292, . Filaments not inclosed in copious mucilage to form thalli 294 . Sheaths containing 2 or more trichomes. Sacconema . Sheaths containing but 1 trichome_—__--------------------------------------- 293 . Trichomes bearing cylindrical gonidia adjacent to the basal heterocyst; enveloping mucilage not hard and granular (al- though firm in 1 species); thalli free-floating or attached____ Gloeotrichia . Trichomes without gonidia; colonial mucilage hard, often gran- ular; thalli attached; trichomes radiate or often parallel in ex- panded gelatinous masses —_--.--------—-—--—--—-----——_-------= Rivularia . Filaments freely branched, the basal portion of the branches inclosed for some distance within the sheath of the primary filament; not epiphytic _—________ Dichothrix . Filaments seldom or not at all branched; branches not inclosed in the sheath of the primary filament; plants usually epiphytic; solitary or gregarious. _-_____________-___»_ Calothrix (in part) . Trichomes exhibiting true branching (branches arising as a result of cell division in 2 planes) —_______--------------------------------- 296 . Trichomes exhibiting false branching, or without branches ___--------------- 299 . Trichomes and lateral branches uniseriate; heterocysts lateral, mostly on the ends of short branches -__.----_-_--------- * Nostochopsis [ 598 ] . Trichomes and lateral branches multiseriate with wide muci- laginous sheaths, or uniseriate with close, firm sheaths; hetero- cysts not/ontthe ends of short lateral branches ee 297 . Filaments uniseriate; sheaths firm, close; heterocysts oblong EO “ey limebraca eae oo oo near te Ose ee ee Hapalosiphon (cf. Stigonema ocellatum ) . Filaments multiseriate’ (rarely uniseriate in part), with wide mucilaginous sheaths; heterocysts compressed, spheroidal, usually lnteralvonva-vesetative (cell: uses saa mete Aieee Ne ee eee eee 298 . Branches as wide or nearly as wide as the main filament; hormo- gonia not formed in the apices of the branches__.___-_»_»_»____ Stigonema . Branches narrow, erect, with hormogonia formed in their apical TES IOWA eee nj on Ria Rle es he Beg Aa Lar Be ee Re Fischerella * richomes cwithoug,branchesee et wee aie ea Ne 800 arichomes; with false branches. o sie Ca oe) eee ee eee un ae 810 . Trichomes with a basal heterocyst (sometimes intercalary hetero- cysts also): (sheath firm\and definite. 2 = 322 2) Microchaete . Trichomes without a firm sheath; heterocysts either always ter- minalwonsalwaysesitercalary == sss seal eee es See 301 » Eleterocystsi always) terminals: = 2058 oe) 8 es ee ee 302 ou Lleterocysts) always: intercalanys =. ee 803 . Heterocysts at one end, rarely at both ends, of the trichome; gonidia formed adjacent to the heterocysts__._______________. Cylindrospermum . Heterocysts at both ends of the trichome; gonidia remote from thephetenocy sts a. te eee Pore ee ee ree Anabaenopsis . Plant formed of many trichomes, often lying parallel to one EN GUOLCAY=) oy ee sea eee Sua hatn A, Nat pale so) Maple Be) heh Sell Greet DA hay ARWUED Ary ie Se DPA att 804 . Trichomes solitary or, if gregarious, entangled, not parallel _____. 306 . Trichomes surrounded by copious mucilage, forming hollow, attached, tubular or bullateamasses ses seeeen ee eee Wollea . Trichomes not forming attached, tubular or bullate masses, but occurring in free-floating bundles or fascicles __._.__.__-___________. 805 . Trichomes very slightly tapering toward both apices; many within free-floating macroscopic flakes of definite shape; gonidia always solitamy:—--2/=5 Siiat ves aa ee ee Aphanizomenon 305. Trichomes not tapering toward the apices; forming flakes of irregular outline; gonidia usually in a series (solitary in some SPECles,) |. kat ster tk se Es GY ee a ees Rl Anabaena (in part) 306. Trichomes solitary, planktonic among other algae» 807 306. Trichomes aggregated in a gelatinous mass of definite or in- definite: ‘Shapess=<4 "ae tte ke. | xe Die Bs 308 307. Cells disc-shaped, much shorter than wide; heterocysts com- pressed ___. PD) fe Last 0) Pe Ais Sa SRS RnR, Py ees Sek ST A PP Nodularia 307. Cells not disc-shaped but globose to cylindrical; heterocysts MOts COMpressed ewes mek es Fe ee i as Anabaena (in part) 308. Plant mass of definite shape, the periphery of the colonial mucilage forming aytemument ses a ee Nostoc 308. Plant mass not of definite shape; colonial mucilage soft, not bounded’ by. .a/firmtegument 22 eee 309 309. Trichomes forming small packets, entangled, sometimes sub- parallel, inclosed in a gelatinous sheath _____.-__-_______-_-__- Aulosira 309. Trichomes not forming packets, individual sheaths lacking, or MOtydehinite 2. | RUF eas Bod Neat i stale Anabaena (in part) 310. $10. 811. 811. Branches usually arising in unilateral pairs about midway be- tween the heterocysts of the main filament; sheath firm and lamellate: rarely vhomogeneous 225 ee Scytonema Branches arising singly, just below a heterocyst or a series of them_—_ 311 Filaments aggregated, somewhat radially arranged in a muci- laginous layer; branching regularly dichotomous; heterocysts S10) ey a a Se ee Diplonema Filaments solitary or aggregated, sometimes forming free- floating, cottony tufts; branching not dichotomous, arising from beneath a heterocyst or series of heterocysts Tolypothrix [ 595 ] Glossary Terms Relating to Fresh-water Algae Abscission: separation of a branch or portion of a thallus by degeneration of cells at its base, or by constriction. Achromatic: without color. Achromatin: the material of the nucleus exclusive of the chromatin. Acicular: needle-shaped. Adnate: joined along a relatively broad surface. Aerobic: using free oxygen in respiration. Agglutinate, Agglutinated: sticking together; adherent, as with mucilaginous sheaths. Akinete: a spore produced from a vegetative cell which has developed a thick wall about a concentrated food reserve. Akontae (Akontean): plants in which neither vegetative cells nor reproductive cells have flagella. Alveolar: with cavities or pits. Amoeboid: like an amoeba in locomotion or in nutrition; creeping by pseudo- odia. Agari without definite shape. Anabaenin: a pigment found in the blue-green algal genus Anabaena. Anaerobic: carrying on respiration without the use of free oxygen. Anastomose: referring to sheaths, filaments, or thalli which intermittently join and separate; sometimes joining in such a way as to form a network. Androsporange, Androsporangium: box-like cell which produces a special spore, androspore, which develops into a dwarf male plant (Oedogoniaceae ). Androspore: a spore which gives rise to an epiphytic dwarf male plant (Oedo- goniales ). Anisogametes: sex cells of a plant slightly dissimilar in size, shape, or behavior. Alternation of generations: a life cycle in which both asexual and sexual plants occur, one giving rise to the other by the production of spores, and by the fusion of gametes. Annular: ring-like. Antapical: posterior; basal; opposite the apex. Antapical plates: sections of the cell wall of Dinoflagellatae at the posterior pole. Antheridium: a male gametangium or sex organ. Antherozoid: a male gamete; sperm, or spermatozoid. Apex (Apical): forward tip; anterior end. Apical plates: sections of the cell wall of Dinoflagellatae at the anterior pole. Apiculate: abruptly tapered to a fine point. Aplanogametes: non-flagellated gametes. Aplanospore: non-motile asexual spores, formed one to several in but not the same shape as a parent cell. Aplanosporangium: cell which gives rise to aplanospores. Apposed: paired; opposite in definite relation to one another. Appressed: pressed together; closely adjoined. Arborescent, Arbuscular: branched in tree-like fashion; bushy. Arachnoid: like a web. [ 596 ] Arcuate: arched, bow-shaped, sharply crescent-shaped; strongly curved as in a drawn bow. Areolate: with openings; with thin areas (areolae), usually circular, in the wall. Articulate, Articulated: jointed; with segments. Asexual: referring to reproduction in which spores rather than gametes are used. Asexual auxospore: a resting stage formed without union of gametes (diatoms ). Attenuated: narrowed or tapering toward the ends. Autocolony: colony of cells formed by the division of one or more cells of a mother colony; or by internal division of a cell to form a miniature colony (see Pediastrum, Oocystis, Volvox). Autospore: a small replica of the parent cell formed internally, one or several together. Autotrophic: self-feeding; able to manufacture food. Auxospore: a resting spore formed by some diatoms, either sexual or asexual. Axial chloroplasts: chloroplasts in the median plane of a cell, arranged along a median line. Axis: the central or median plane of a figure, cell, or plant. Azygote, Azygospore: a spore similar in shape and wall markings to a zygo- spore (q.v.) but formed without the union of sex cells. Bacillar: rod-shaped. Basidia-like: club-shaped. Basipetalous: developing from apex toward the base. Benthon: organisms attached on the bottom of an aquatic habitat; deep-water life. Biconic: in the shape of two cones with their bases together. Bifurcate: divided into two portions, or branches, as in the forking of spines or lobes. Bilateral: on two sides; arising on two sides; the same on two sides. Biseriate: in two rows; with two series of cells. Blepharoplast: small body (the central body) associated with the nucleus; in some flagellates, the body from which the flagellum arises. Bulbous: bulb-like, swollen at one end. Caespitose (or Cespitose): clustered; in fascicles; forming a mat or tangle. Calose: a substance appearing in the walls of the Siphonales which replaces cellulose. Calyptra: a thickening; a thick covering or membrane at the tip of a trichome or organ (e.g. in Oscillatoria spp., Phormidium spp. ). Canal: tube; fine channel, as in the wall of diatoms. Capitate: with a head; swollen at one end, or at both ends. Capitellate: slightly swollen or enlarged at one end. Carotene, Carotin: an orange-colored pigment, usually associated with chloro- hyll. Gasiberne Carpogonium: female sex organ in the Rhodophyceae. Carpospore: spore arising from the fertilized egg in some Rhodophyceae. Cartilaginous: tough but pliable. Catenate: joined to form a chain. Caudus: a tail-piece. Central body: the central region of the blue-green algal cell, which upon staining shows the presence of chromatin granules; a granule associated with the nucleus in flagellated organisms. Central nodule: the thickening on the inner face of the wall of some diatoms. Centricae: diatoms which are radially symmetrical. Centrifugal: developing from the center outward, or from a point outward. [ 597 ] Centripetal: developing from without inward, or from exterior to interior. Centrosome, Centriole: a small body, usually lying just outside the nucleus; in flagellates a granule functioning in the neuromotor system. Cespitose: See caespitose. Chitin: a hard substance, C15 Hog O10 Ne, found in skeletons of lower animals and in cell walls of some algae. Chloroplast: a body (plastid) in the cell containing chlorophyll as the pre- dominating pigment. Chlorococcine tendency: evolutionary trend toward the Chlorococcales in the green algae (or in other groups) from a solitary motile cell which has ability to reproduce vegetatively by cell division to a nonmotile type of ae lawn ania or coenocytic) in which vegetative cell division is not used. Chromatophore: a colored body in a cell which has a pigment other than chlorophyll predominating. Chromatic: colored. Chromatin: the material in the nucleus which takes up dyes readily; nuclear material composing chromosomes. Chromoplasm: the portion or part of cell content containing pigments, not in- volving plastids; in Myxophyceae the cytoplasm just within the cell wall and exterior to the “central body.” Chromulinad: a type of cell similar to Chromulina which has one flagellum. Chroococcoidal: in shape or arrangement similar to Chroococcus; cluster of round cells. Chrysochrome: brown pigment found in Chrysophyceae. Cilium (pl., Cilia): fine, hair-like extensions, usually from the outer membrane of a cell; used in locomotion by ciliated protozoa; fibrils on the flagella of the Heterokontae. Cingulum: band within the diatom cell which holds the two overlapping sec- tions of the wall together. Circinate: coiled, rolled; twisted. Cirque: arranged in a circle or nearly so. Citriform: lemon-shaped. Clathrate: with openings; intermittent spaces. Clavate, Claviform: wedge-shaped. Coalesced, Coalescent: joined, united; grown together. Coccoid: round; spherical; cells as in Chroococcus, Aphanocapsa. Coenobe, Coenobium: a colony of cells arranged to form a hollow sphere. Coenocytic: with many nuclei; a thallus constructed of multinucleate cells; a thallus in which there are no cross walls. Collar: narrow neck around the flagellum-opening in a shell or lorica; some- times a sheath at the base of a bristle or hair. Colligate: united, joined, as in some species of Spirogyra which have an exter- nal collar-like piece about the cells at the cross walls. Colony: a group of individuals, joined together or merely inclosed by a com- mon sheath or investing material; a group of cells joined together to form a filament (rarely used in this sense); a cluster of individual plants, closely associated in growth. Commensal: referring to two or more species living in close association and deriving mutual benefits. Complanate: level, smooth, even, plane. Concentric: layers or structures with a common center. [ 598 ] Confluent: growing into one another; soft sheaths which run together or which become intermingled. Conidium: a spore cut off from the tip of a cell, or from a filament. Connate: pointed; united for a short distance as in the basal portion of branches. Constricted: pinched in; deeply incised. Contiguous: near-by, adjoined. Conjugation: union of gametes from cells or from plants which become joined, the gamel.s moving together in an amoeboid fashion; literally, a yoking together. Contorted: irregularly twisted. Contractile: able to expand and contract. Contractile vacuole: cavity in the cytoplasm surrounded by a membrane which shows pulsating actions, compressing and expanding. Convolute: rolled together; rolled inward from a margin. Cordate, Cordiform: heart-shaped. Coronula: a crown of cells at apex of oogonium in Characeae. Cortex, Corticating: a layer of cells or filaments which invest or grow around a central core (cell or filament), forming an inclosing layer (e.g., some Rhodophyceae, Chara). Corymb (Corymbose): a flat-topped cluster (especially when sequence of development is from outside toward the center ). Costa (Costate): rib (adj., ribbed). Craticular stage: a condition in diatoms in which successively formed cell walls nest within one another. Crenate: with a wavy surface or margin. Crenulate: finely crenate; with small scallops. Cuspidate: furnished with a tooth. Cruciate: cross-like in arrangement. Cryoplankton, Cryovegetation: plants which live in snow, especially perpetual snow banks of alpine situations. Cuneate: wedge-shaped. Cushion-like: said of a thallus composed of a mound of cells, two to many layers of cells; parenchymatous. Cylindrical: elongate and round in cross section with parallel lateral margins. Cyst: a dormant, vegetative reproductive cell, usually with a heavy wall. Cystocarp: a structure that develops around the fertilized egg in the Rhodo- phyceae in which spores (carpospores) are formed. Cystosome: soft portion of periplast of flagellates in the food-absorbing region. Cytopharynx: a canal extending back from the anterior opening in flagellates; narrow part of gullet in euglenoids. Daughter cells, Daughter segments: cells or portions of thallus that are des- cended from the same mother cell or parent plant. Decumbent: growing horizontally but with the segment ascending (c.f. pros- trate ). Deliquescent: degenerating; dissolving. Dendroid: tree-like, branching as in a tree. Dentate: toothed; with blunt-pointed projections. Depressed-globose: not quite spherical; like a slightly flattened sphere. Diastole: period of expansion in action of contractile vacuole. Diatomaceous earth: grayish-colored silicious deposit of diatom shells. Diatomin: brown pigment found in diatoms. Dichotomous, Dichotomy: divided or forked into two parts; forking branches. Dioecious:“two households”; with male and female organs on separate plants. [ 599 ] Diffluent: flowing off; dissolving away. Diploid: referring to nucleus with double number of chromosomes; a generation of plant life cycle before reduction division (cf. haploid). Disarticulate: unjointed; with segments separated. Disc (Discoid): a circular, flat body; a plate. Dissepiment: a cross partition; a cross wall. Distal: referring to the forward end; opposite from basal. Distromatic: occurring in two layers, or at two levels. Divaricate: widely separating; spreading. Diverging: extending from a common point in different directions. Dolioform: barrel-shaped. Dwarf male: a 1-celled or few-celled male plant epiphytic on the female, usually on or near the oogonia. Echinate: spiny. Egg: female gamete; non-motile heterogamete. Emarginate: a margin which is not even, but notched or with concavities. Endocellular: within the cell. Endogenous: arising from within. Endophyte (Endophytic): plant living within another plant but not neces- sarily parasitic. Endospore: a spore formed within a cell; a spore cut off from the tip of a protoplast as in Chamaesiphon. Endozoic: living within an animal but not necessarily parasitic. End piece: the unsheathed tip of a flagellum; a tail piece. Entire: smooth, not toothed or roughened. Envelope: a sheath or mass of mucilage which incloses a cell or colony. Epicone: the upper or anterior half of a dinoflagellate cell. Epiphyte (Epiphytic): plant growing on another plant but not necessarily parasitic. Epitheca: the part of the cell wall of a dinoflagellate above the transverse furrow. Epivalve: the upper or larger of the two parts of the wall of diatom cells; sometimes the upper part of dinoflagellate cells. Epizoic: attached to or growing on animals. Erect oogonium: oogonium (in the genus Bulbochaete) borne at the end of a suffultory cell (q.v.) that has been divided by a transverse wall. Euplankton: true plankton; open-water drifting organisms. Eutrophic: referring to older, shallow lakes; highly productive. Evanescent: disappearing, vanishing, especially with advanced age. Evection: to set aside or to push one part above another. Excentric (or Eccentric): off center. Exospore: the outer membrane of a zygospore wall. Eye-spot: pigment-spot; granule which is sensitive to light and usually dark red in color; found in some swimming spores or in motile vegetative cells. False branch: a branch formed by a slipping to one side of a section of a fila- ment; a branch not formed by lateral division of a cell. Family: an aggregation of cells or of similar plants. Fascicle ( Fasciculate ): a bundle or cluster. Fastigiate: narrowed to a point. Fenestrate (Fenestration): windowed; with openings. Fibrils (Fibrillate, Fibrillose ):fine fibers; slender strands. Filament: a linear arrangement of cells; thread of cells, together with sheath (Myxophyceae ). [ 600 | Filiform: thread-like. Fission: division of a cell by splitting to form two, not necessarily equal, parts; cell division without mitosis. Flaccid: soft, drooping, not rigid. Flagellum: a stout, whip-like organ of locomotion which arises within the cell. Flagelliform: whip-shaped. Flange: a longitudinal ridge extending vertically from a cell wall. Flexuous: pliable; not firm or rigid. Floccose, Flocculent: cottony, or wooly; matted. Floridean starch: a carbohydrate food reserve in the Rhodophyceae. Foliaceous, Foliose: like a leaf. Frond: a flat, leaf-like plant; a foliaceous thallus. Frustule: the shell of diatoms. Fusiform: an elongate figure broadest in the middle and tapering at each end; spindle-shaped. Gametangium: a gamete-producing cell; sex organ. Gamete: a sex cell, male or female reproductive cell. Gelatinous envelope: a sheath or investment of mucilage-like substance. Geniculate: with knee-bendings. Germling: young plant developed from a spore or zygote. Gibbous: swollen in a regular curve. Girdle: a band or belt, usually median; part of the structure just within the wall, and lateral in the cell, which holds the valves of diatoms together. Girdle view: a lateral or side view of a diatom, showing the overlapping of the two wall sections. Glaucous: grayish-green; green with a whitish overcast or ‘bloom.’ Glomerate: in compact clusters. Glomerule: a small compact cluster. Glycogen: a white carbohydrate, amorphous, similar to starch; a food reserve. Gonidium: a spore-like, thick-walled reproductive cell (see akinete ). Gonimoblasts: short filaments developing from the zygote in certain Rhodo- phyceae which cut off spores (carpospores ) at their tips. Granulose: furnished with granules. Gregarious: growing in clusters or in close associations; not solitary. Gullet: an opening through the membrane at anterior end of flagellates (euglenoids ). Gynandrosporous: in Oedogoniaceae, a condition in which androspores (spores which produce male plants) are developed in the same filament in which oogonia (female organs ) occur. Gypsum: granules of calcium sulphate found in the cells of some desmids. Haematochrome: a red pigment apparently functioning as a light screen, appearing occasionally in green algae, sometimes permanently present. Haploid: containing the half number of chromosomes (nucleus with the 1-n number); referring to a generation in the life history following reductive division. Haplontic: a haploid or 1-n generation; referring to a cell containing the re- duced number of chromosomes. Hapteron (pl. Haptera): an anchoring, finger-like organ at the base of a young lant. Heleoplanktone floating organisms in a small, shallow pond. Helotism: a form of symbiosis; two different species in close association (lichens ). [ 601 ] Hemicellulose: a hard carbohydrate somewhat similar to cellulose in walls of some algae; more common in cell walls of higher plants. Heterocyst: a specialized cell in some filamentous Myxophyceae which is usually larger than and a different shape from the vegetative cells. Heterogametes: sex cells unlike in size, shape, and behavior. Heterothallic: from two different thalli; of reproductive structures or cells borne on different parents. Heterotrophic: obtaining food in soluble or particulate form; not photosynthetic. Heterotypic division: reductive division of a nucleus; segregation of chromo- somes. Hirsute: hairy. Holdfast cell: the basal cell of a filament modified to form an attaching organ. Holophytic: obtaining food by photosynthesis. Holozoic: ingesting food like an animal. Homothallic: from similar thalli; of gametes from the same parent. Homotypic division: nuclear division (mitosis) involving a splitting of chrom- osomes; the chromosome division immediately following first meiotic division. Hormogonium, Hormogone: a fragment of a filament; a short section broken away from a mature trichome (Myxophyceae). Hormospore: a vegetative spore-like body formed from a short section of a filament that becomes invested by a thick membrane. H-shaped pieces: sections formed when a filament of cells dissociates; the H- shaped pieces formed as a result of the fact that cell walls are in two pieces which overlap in the midregion, the line of cleavage being here rather than at the cross walls of the filament. Hyaline: colorless; transparent. Hypocone: the lower part or posterior half of a dinoflagellate below the me- dian girdle. Hypotheca: the lower half of the cell wall of a dinoflagellate below the median irdle. H Weccilce: the lower or smaller of the two parts of a diatom cell wall. Hypha, Hyphal filaments: threads which inclose the central, axial filament in some Rhodophyceae (Lemanea). Hypnospore: small, thick-walled, asexual spore; especially the spores formed underground in Botrydium. Idioandrosporous: having androspores formed in filaments separate from those in which the female organs (oogonia) are produced (e.g., in Oedogonium). Imbricate: overlapping; joined in an overlapping series. Incised: cut, with narrow slits. Indurate: hard. Inferior pore: a pore in the wall in the lower part of an oogonium (Oedogon- iaceae ). Initial cell: cell which generates other cells, or which gives rise to tissue. Inner fissure: the inner part of the raphe in the pennate diatoms. Integument: a covering, sheath, or envelope. Intercalary: appearing between, inserted (as between cells), rather than ter- minal or marginal. Intercalary bands: bands which help to hold the two valves of the diatom cell together. Interpolate: to place between. Intestiniform: shaped like an intestine; tubular. Intravitam: within living tissue; e.g., to stain a living cell. [ 602 ] Intricate: tangled. Investment: an inclosing membrane or envelope. Isochrysid: cells bearing two flagella of equal length in Chrysophyceae. Isodiametric: having diameters equal. Isogamous: sex cells similar to one another in size, shape, and behavior. Isokontae (Isokontean): plants which have vegetative or reproductive cells equipped with flagella (usually 2) of equal length. Isthmus: narrow part of the desmid cell connecting two semicells (cell halves). Karyokinesis: division of the nucleus; segregation of nuclear material in cell division. Keel: a flange on the valve of some diatoms. Laciniate: torn; with a cut or lacy margin, or lace-work surface. Lacuna (Lacunate): an opening (with spaces). Lageniform: flask-shaped. Lamellate, Lamellated, Lamellose: layered, with layers. Laminate: plate-like. Lanceolate: lance-shaped; long and narrow with subparallel margins but tapered at the apex. Lateral conjugation: sexual reproduction involving a joining to two contiguous cells in the same filament (e.g., in some species of Spirogyra). Lenticular: lens-shaped; with two convex surfaces. Leucosin: a white food reserve material found in most Heterokontae. Limnoplankton: drifting organisms in lake water. Littoral: in shallow water near shore; on the shore. Longitudinal furrow: a groove in dinoflagellates lying parallel with the long axis, at right angles to the transverse furrow. Loculiferous: with small chambers or compartments. Lorica: a shell or case built around but separate from the living protoplast. Lumen: a cavity, especially the space left in a cell after spores or gametes have escaped. Lubricous: slippery. Lunate: crescent-shaped; moon-shaped. Macrogamete: the larger of two sizes of swimming gametes (e.g., Stichococcus). Macrandrous: having male plants that are as large or nearly as large as the female plants (Oedogoniaceae ). Macrozoospores: the larger of two sizes of zoospores (e.g., Ulothrix). Mammillate: with nipple-like protuberances. Marl: calcareous deposit formed by some algae, especially Chara. Matrix: investing or surrounding matter, especially mucilaginous material sur- rounding cells. Median constriction: a pinched-in or narrowed region in central portion of cell or thallus. Membranous, Membranaceous: like a membrane, a thin layer. Meristematic: referring to cells with the ability to divide rapidly. Mesospore: middle one of three layers in the wall of zygospores. Metabolic: changeable in form, varying in shape from time to time (e.g. Euglena). Microgamete: the smaller of two sizes of swimming gametes (e.g., Stichococ- cus ). Microspores: minute, spore-like bodies formed by some diatoms, questionably sexual or asexual. Microzoospores: smaller of two sizes of zoospores in Ulothrix; spores which swarm for 2 to 6 days without germination. [ 603 ] Mitosis (Mitotic): nuclear division by formation of spireme thread and chrom- osomes. Moniliform: resembling a string of beads. Monaxial: with one axis or with one row of cells. Monoecious: “of one household”; with both male and female sex organs on the same plant. Monosiphonous: formed of a single tube or filament, without cross walls. Monospores: asexual spores cut off from tips of branches, or from vegetative cells (e.g., some Rhodophyceae ). Monostromatic: referring to a prostrate thallus, one cell in thickness. Mother cell: the cell which divides itself (often internally ) into daughter cells. Motile: able to move; swimming. Multicellular: composed of many cells. Multiaxial: with more than one axis; with more than one row of cells. Multinucleate: with many nuclei. Multiseriate: with more than one row of cells; with many filaments. Nannandrous: with dwarf male plants, minute male filaments growing epiphyti- cally on the female plant (Oedogoniaceae ). Nannoplankton: very minute aquatic organisms (see plankton). Nannospores: very small vegetative cells arising from rapid cell division. Napiform: turnip-shaped. Naviculoid: like Navicula; like a little boat. Necridium: a dead cell; a somewhat differentiated cell in some filamentous Myxophyceae which permits fragmentation to occur readily. Nekton: organisms capable of swimming against water currents. Neuromotor apparatus: the bodies and fibrils interconnecting flagella and at- taching them to the centriole and the nucleus (e.g., euglenoids ). Neutral spore: a vegetative spore arising from increased cell division in certain Rhodophyceae. Nodule: a small knob. Nonparticulate: referring to substances in solution. Obconic: cone-shaped with the broader end foremost. Obovoid: inversely ovoid; with the broader end anterior or outermost. Obpyriform: inversely pear-shaped, with the broader end anterior or outermost. Ochromonad: a type of cell similar to Ochromonas (with two flagella.of un- equal length). Ocelli: raised thickenings on the walls of diatoms. Ocrea: a sheath; a layered envelope. Oligotrophic: referring to younger, deep lakes; poor in production. Ontogeny (Ontogenetic): life history of an organism. Oogamy: reproduction involving gametes of which one is an egg. Oogone, Oogonium: one-celled female reproductive organ, usually containing a single egg. Oolith: a stone-like concretion involving a fossil surrounded by deposits of calcareous material. Oospore: a thick-walled spore formed from a fertilized egg. Operculum: a lid or cap. Orbicular: spherical. Orbiculate: circular in outline. Oval: an elongate figure with convex margins and equally rounded at the ends. Ovoid: shaped like an egg; an elongate figure with unequal curvature at the poles, one being broader than the other. Ovate: see oval. [ 604 | Outer fissure: the upper part of the raphe (q.v.) in pennate (bilaterally sym- metrical) diatoms. Packet: compact cluster or aggregate of cells, often cubical. Palmella stage: a condition resembling Palmella, in which a motile cell has lost organs of locomotion, become quiescent, and undergone division to form clumps of daughter cells encased in mucilage. Palmelloid: similar to Palmella; forming clumps of mucilage-encased cells. Panduriform: fiddle-shaped; an elongate figure, broadest at the anterior end and with concave lateral margins. Papilla (Papillose): a small nipple-like swelling (adj.: bearing papillae ). Paramylon: a solid carbohydrate food reserve formed by certain euglenoids. Parenchymatous: cushion-like; composed of a mound of cells. Parietal: lying along the wall; peripheral in the cell. Parthenospore: a zygote-like spore produced from a single gamete which de- velops a thick wall. Patent oogonium: oogonium (in Bulbochaete) borne on a division of the suffultory cell (q.v.) that has been cut off obliquely from the lower cel rather than by a transverse wall; free; free spreading. Pectin, Pectose: gelatinous substance (carbohydrate) found in the wall of many algae. Pedicel: a stalk or stem, often delicate and short. Pelagic: floating organisms, especially in the ocean; surface organisms. Pellicle: a thin membrane or sheet. Pellucid: translucent, clear. Penicillate: brush-like. Pennatae: diatoms which are bilaterally symmetrical. Pericentral cell: a cell (one of several) inclosing a central cell or filament. Peridinin: a reddish pigment found in some dinoflagellates. Periphyton: organisms attached at the water level to aquatic plants. Periplast: the bounding membrane, especially the cell membrane of euglenoids. pH: relative amount of free hydrogen ions; indicator of acidity or alkalinity. Pharyngeal rods: bodies lying parallel with the gullet (e.g., Peranema). Phototactic: movement or orientation with respect to light stimulus. Phycochrysin: brown pigment found in Chrysophyceae (chrysochrome ). Phycocyanin: a blue pigment in solution in cells of Myxophyceae and some Rhodophyceae. Phycoerythrin: red pigment in Rhodophyceae and some Myxophyceae. Phycopyrin: brownish-red pigment in some dinoflagellates. Phylogeny: racial development: racial history. Pigment-spot: See eye-spot. Piliferous, Pilose: hairy. Placoderm desmid: desmid usually constricted in the midregion, with wall in two sections. Plakea: plate of cells formed by successive divisions from mother cell. Plane: smooth and even, not folded. Planoconvex: with convex surface opposite a flat surface. Planogamic heterogamy: condition of having gametes of different size, motile and non-motile. Plankton (Planktonic): floating organisms unable to swim against currents, drifting. Plasmodium: naked protoplasm as in slime molds. Plastid: any one of several kinds of bodies in the cytoplasm of a cell. Plicate: folded. [ 605 ] Plurilocular gametangium: closely arranged cluster of cells, each producing a gamete. Polar: at the end of an axis. Polar nodule: the body on the inner wall at the ends of some diatoms. Polygonal: with many sides. Pore: a hole or opening in a wall or membrane; mucilage pore; pore for en- trance of antherozoid, etc. Postcingular plates: sections of the wall of dinoflagellates lying between the median girdle and the antapical plates; posterior plates. Precingular plates: sections of the wall of dinoflagellates lying between the median girdle and the apical plates; anterior plates. Processes: extensions; lobes, arms, etc. Proliferate: to develop a new thallus or branches by vegetative cell division. Prostrate: lying down; horizontal. Protonema; Protonema stage: prostrate filaments arising from germination of spore, sometimes giving rise to upright branches. Protophyte, Protophyta: simplest of plants; often referring to organisms with both plant and animal-like characteristics. Protoplast: the living material (protoplasm) of a cell. Psammon: microorganisms inhabiting beaches or sandy shoals. Pseudocilia: false cilia; hair-like extensions similar to flagella in shape but not used for locomotion. Pseudofilament:a thread of cells incidentally arranged in a linear series; not a true filament. Pseudoparenchymatous: resembling a mound of cells but actually constructed of closely grown filaments. Pseudoraphe: a false raphe (q.v.); a clear median area in the valves of some diatoms which forms a line resembling a raphe. Pseudopodium: a false foot; a root-like extension of protoplasm usually in- volved in locomotion (see Chrysomoeba). Pseudovacuoles: false vacuoles; pockets of gas or mucilage in the cytoplasm resembling vacuoles, and usually light-refracting (Myxophyceae). Pulsating vacuoles: vacuoles which contract suddenly and expand slowly. Pulsule: non-contracting vacuole (as in dinoflagellates). Pulverulent: finely granular; powdery. Pulvinate: cushion-shaped. Punctate: with minute points or dots; with cylindrical pores. Pyramidal: in the shape of a pyramid. Pyrenoid: a proteid granule which collects starch, either within a chloroplast, on its surface, or free within the cytoplasm. Pyriform: pear-shaped, with narrow end foremost. Quadrate: square; arranged to form a rectangle. Quadripartition: division to form four units. Raceme: a cluster of reproductive structures which mature inwardly from without, the youngest structure being in the center or at the top of the cluster; racemose (adj.), arranged like a raceme. Radial: along the radius; radiating. Raphe: a fissure, slit, or channel in the wall of some diatoms. Rectilinear: arranged in straight rows in two directions. Reniform: bean-shaped; kidney-shaped. Repand: referring to cells having the lateral walls concave or undulate. Replicate: folded, especially the end walls of some species of Spirogyra. Reservoir: posterior, enlarged portion of gullet in flagellates (euglenoids ). [ 606 | Reticulate: netted; arranged in a net-work; covered with thickenings in the form of a net. Retuse: rounded at the apex but with an incision (as in heart-shape ). Rhabdosomes: small rods in the periphery of cells in some dinoflagellates. Rhizoidal: root-like, resembling rhizoids. Rhizoplast: fibril connecting flagellum base with centrosome; part of the neu- romotor apparatus in flagellated organisms. Rhizopodal: moving as an amoeba. Rhizopodal tendency: evolutionary trend from a swimming cell to a condition in which the organism is amoeboid. Rhomboid: a parallelogram with oblique angles and adjacent sides unequal. Rostrate: with a beak. Rostrate-capitate: with a beak which has a swollen tip. Rugose: roughened, as with ridges and furrows. Saccate: like a sac; balloon-shaped. Saccoderm desmids: desmids unconstricted in the mid-region and with the wall in one piece (cf. placoderm desmids ). Saggitate: arrow-shaped. Saprophyte: organism that obtains food from dead organic matter. Sarciniform: in the shape and arrangement of a cubical packet. Scalariform: ladder-like, referring to conjugation by tubes connecting two filaments. Scale-like: like a small husk or membrane. Schizophycean phycoerythrin: red pigment in the Myxophyceae. Scrobiculate: pitted, usually with round, shallow depressions. Scytonemin: a pigment found in the sheath of some Scytonema. Semi-anaerobic: see anaerobic. Semicell: cell-half of a desmid. Semilunar: somewhat crescent-shaped. Septa: a cross wall or partition. Seriate: in a linear sequence or series. Seta: a hair or bristle; sometimes a tail-piece. Setiferous: bearing a seta or hair. Sexual auxospore: spore formed by union of gametes, or from parthenogenetic development of gametes (diatoms). Sheath: a covering, an envelope, usually relatively thin and composed of mucilage. Sigmoid: like the letter S. Silicious: containing silicon. Sinus: the incision of a desmid cell in the midregion; any conspicuous invag- ination. Siphon: organ involved in the digestive apparatus of some flagellates. Siphonaceous: referring to a tubular thallus which has no cross walls (e.g., Vaucheria). Spatulate: elongate, gradually enlarged and bluntly rounded at one end. Spermatia: cells acting as male gametes; non-motile male cells, as in Rhodo- phyceae. Spermatozoid: a male gamete. Spermocarp: one of the investing cells developed about the fertilized egg (Coleochaete ). Spongiose: like a sponge; like a soft, thick mat. Spicules: needle-like scales or hard bristles. Spinescence: spines; spine arrangement. [ 607 ] Sporangium: a cell in which spores are produced (often zoospores ). Spore: a one-celled, asexual reproductive element, with or without a wall. Statolith: granule functioning as a balancing organ relating the cell to gravity. Statospore: spore smaller than the parent cell, formed within the shell (frus- tule) of diatoms. Stauros: a stake; a stout, pole-like extension; an external central nodule in some diatoms. Stellate: star-shaped. Stephanokontae: plants which have motile reproductive cells furnished with a crown of flagella. Stigma: the red granule or group of granules making up the light-sensitive spot in zoospores and flagellates. Stipe: a stalk. Stratum: a layer. Striae: delicate, long, narrow markings. Stroma: supporting tissue or mass of cells serving as a base for upright branches or other organs. Sub—-: slightly or nearly, as subglobular; under; beneath. Subbiconic: nearly or somewhat double cone-shaped. Subhexagonal: somewhat six-sided. Subparenchymatous: somewhat cushion-like; approaching the mound-like ar- rangement of cells, in two or more layers. Subpyriform: somewhat pear-shaped. Suffultory cell: a cell resulting from the division of a vegetative cell, the upper segment of which forms an oogonium, the lower segment a some- what enlarged suffultory cell. Sulcus: the longitudinal furrow in dinoflagellates. Superior pore: a pore in the upper part of an oogonium (Oedogoniaceae ). Supramedian: slightly above the median plane. Suture: furrow or groove; trough between plates in wall of dinoflagellates. Symbionts: two dissimilar organisms living together in close association. Symbiotic: a condition in which two different organisms live together. Systole: contraction period in action of pulsating vacuoles. Tangential: section or cut made at right angles to the radius. Tegument: a sheath or envelope. Terebriform: twisted or twist-hooked, augur-shaped. Test: an external shell inclosing the protoplast (e.g. Trachelomonas ). Tetrad: four cells formed by two divisions from a spore mother cell. Tetrasporine tendency: evolutionary trend in green algae from a motile uni- cell through a palmelloid condition to a Tetraspora-like expression, and then to a filamentous form. Thalloid: like a plant body which has no roots, stems, or leaves. Thallus: a plant body in which there is little or no differentiation of cells to form tissues. Tie cells: cells in the thallus of some red algae which connect peripheral cells to a central axis. Tomentose: covered with numerous fine hairs. Torulose: twisted; flexuous, as in irregularly spiralled species of Anabaena. Transverse: across the short diameter. Transverse furrow: groove extending (at least partly) around the dinoflagel- late cell in the midregion. Trapezoid: a plane figure which has two parallel sides. Trichites: silicious spicules; a tuft of bristles. [| 608 ] Trichocyst: an organelle in the cell which throws off a fibril; a stinging thread. Trichogyne: narrow extended part of female sex organ (carpogonium) in the Rhodophyceae. Trichome: a hair; a thread of cells without the investing sheath in Myxophyceae. True branching: branched by lateral division of a cell in a main filament. Truncate: flat at the top; flatly rounded. Tubercle (Tuberculate): small raised thickenings on the wall, or at the base of spines. Tychoplankton: floating or free-living organisms in shallow water of a lake intermingled with miscellaneous vegetation, usually near shore. Travertine: a deposit of chalk-like calcareous material. Umbonate: with a cone-shaped protrusion. Undulate: wavy. Uncinate: with a hooked apex. Unilateral: on one side; arising from one side only. Unilocular sporangium: a solitary, one-celled spore-producing organ. Uniseriate: arranged in a single row or series. Uninucleate: with one nucleus. Utricle: a small sac; a tubular bag or vesicle. Vacuole: a space in the cytoplasm filled with cell sap, sometimes containing granules. Valves: the two parts of the wall of diatoms, one of which is larger and fits over the smaller as a lid; the two parts of a dinoflagellate cell. Valve view: view from the top or bottom of a diatom cell so that the broader surface of the valve is seen. Ventricose: bulged or swollen on one side. Vermiform: worm-like. Verrucae: short, stout projections, smooth or armed with teeth. Verrucose: warty. Vertical canals: canals which connect both outer and inner fissures of the raphe (q.v.) in one part of the diatom cell with the fissures in the other part. Vesicle: minute sac or cavity. Volvocine tendency: evolutionary trend in green algae from a single motile cell toward simple colonies, and to colonies containing differentiated or specialized cells. Water bloom: a conspicuous and abundant growth of planktonic algae, some- times appearing suddenly, often forming a surface scum. Xanthophyll: yellow pigment associated with chlorophyll. Zonate: with bands; with concentric layers. Zoospore: a motile, animal-like spore without a cell wall. Zygospore: a thick-walled resting spore resulting from the union of gametes. Zygote: a fertilized egg; a cell resulting from the union of gametes. [ 609 | Bibliography + Important reference work * Deals with Michigan and Wisconsin algae ACKLEY, ALMA B. 1929.” New species and varieties of Michigan algae. Trans. Amer. Microsc. Soc., 48: 302-309; Pls. 35, 36. 1929a.* The algae of Mich- igan. Doctoral thesis, Ohio State University. Abstract. 1930.* The algae of Michigan. Doctoral thesis, Ohio State University. 1932.% Preliminary report on Michigan algae, exclusive of desmids and diatoms. Pap. Mich. Acad. Sci., Arts, and Letters, 15(1931): 1-49. AcTON, ELizaBETH. 1914. Observations on the cytology of the Chroococcaceae. Ann. Bot., 28: 434-454; Pls. 33,34. 1916. On the structure and origin of “Cladophora balls.” New Phytol., 15: 1-10; Figs. 1-5. Acarpu, C. A. 1810. Dispositio algarum Suecicae, Part I. Lund. 1812. Dis- positio algarum Suecicae, Parts II and II. Lund. 1812-1816. Algarum decades, I-IV. Lund. 1817. Synopsis algarum Scandinaviae, adjecta dis- positione universali algarum. 185 pp. Lund. 1824. Systema algarum, Vol. I. Lund. 1827. Aufzahlung einiger in den Ostreichischen Landern gefundenen neuen Gattungen und Arten von Algen, nebst ihrer diagnostik und _bei- gefiigten Bemerkungen. Flora, 10: 625-640. 1828. Species algarum, Vol. 2. Lund. 1828-1835. Icones algarum Europaearum. Leipzig. Acarpu, J. G. 1842. Algae maris Mediterranei et Adriatici. Paris. 1848. Nya Alger fran Mexico. Oefv. Kongl. Sv. Vet.-Akad. Forhandl., 4(1847); 5-17. 1899. Analecta algologica. Observationes de speciebus algarum minus cognitis earumque dispositione. Continuatio V. Lund. AntstroM, E. H. 1936.* The deepwater plankton of Lake Michigan, exclusive of the crustacea. Trans. Amer. Microsc. Soc., 55: 286-299. 1937.* Studies on variability in the genus Dinobryon (Mastigophora). Ibid., 56: 139-156. AutstroM, E. H., and Tirrany, L. H. 1934.* The algal genus Tetrastrum. Amer. Jour. Bot., 21: 499-507; Figs. 1-36. ALExENKO, M. A. 1888. Précis des algues chlorosporées des environs de Khar- kow. Trav. Soc. Nat. Univ. Imp. Kharkow, 21: 141-278. 1891. Matériaux pour servir a la flore des algues du gouvernement de Poltava. Ibid., 25: 47-88. 1894. Flore algues des maris et des tourbes de la vallée du Dnieper dans les limites du gouvernement de Poltava. Ibid., 27: 59-118. 1895. Matériaux pour servir a la flore des algues du gouvernement de Kharkow. Ibid., 28: 81-132. ALLEGRE, CHARLES, and JaHNn, T. L. 1943. A survey of the genus Phacus Dujardin (Protozoa): Euglenoidina. Trans. Amer. Microsc. Soc., 62: 233- 244; Pls. 1-3. ALLEN, T. F. 1880. The Characeae of America, 1-2: 1-14, Pls. 1-6. Boston. 1882. Development of the cortex in Chara illustrated by a series of American species. Bull. Torr. Bot. Club, 9: 37-47. 1883. Notes on the American species of Tolypella. Ibid., 10: 109-117. 1888-1896.+ The Characeae of America. Pls. 1-27. New York. 1900. Three new Charas from California. Bull. Torr. Bot. Club, 27: 299-304. [ 610 J Axuison, F. E., and Morris, H. J. 1930. Nitrogen fixation by blue-green algae. Science, 71: 221-223. AutorcE, P., and LeFevre, M. 1925. Algues de Sologne. Bull. Soc. Bot. France (Session Extraord., Sologne, 1925), 72(Suppl.): 123-150. (This paper is sometimes to be found bound with Vol. 77, 1930. Published bibliographies occasionally cite the latter, rather than the former, volume of this journal, giving either 1930 or 1931 as the date of publication. ) ALTEN, H. von. 1910. Beitrage zur Kenntnis der Algenflora der Moore der Provinz Hannover. Hannover Jahrb. Nat. Ges., 59: 47-69. ANDERSON, Emma N., and WaLKER, Expa R. 1920. An ecological study of the algae of some sandhill lakes. Trans. Amer. Microsc. Soc., 39: 51-85; Figs. 1-17. AnpERSSON, O. F. (O. Borge). 1890. Bidrag till kannedomen om Sveriges Chlorophyllophyceer. I. Chlorophyllophyceer fran Roslagen. Bih. Kongl. Sv. Vet.-Akad. Handl., 16, Afd. 3, (No. 5): 1-19. ANpREESEN, H. 1913. Beitrag zur Kenntnis der Physiologie von Scenedesmus acutus Meyen. Inaug. Diss. Kiel. Arcuer, W. 1861. In A. Prichard, A history of infusoria including the Des- midiaceae and Diatomaceae, 4th ed., London. 1866. [Remarks before meeting of Dublin Microscopical Club, May, 17, 1866]. Quart. Jour. Microsc. Sci., 14 (Vol. 6, n. s.): 268-272. 1867. On the conjugation of Spirotaenia condensata (Bréb.) and of Spirotaenia truncata (Arch.). Ibid., 7: 186-193; Pl. 8, Figs. 1-3. 1868. [No title]. Ibid., 8: 65. 1872. The genus Tetrapedia (Reinsch) with two new forms. Grevillea, 1: 44-47. 1872a. Notice of the genus Tetrapedia (Reinsch) and of two kindred new forms. Quart. Jour. Microsc. Sci., 12(n.s.): 351-366. 1874. Algae and Rhizopoda from the hot springs of Azores. Ibid., 16: 107. 1874a. Notes on some collections made from Furnas Lake, Azores, containing algae and a few other organisms. In J. D. Hooker, Contributions to the botany of the expeditions of H. M. S. “Challenger.” Jour. Linn. Soc. Bot., 14: 328-340. 1877. New species of Oocystis. Quart. Jour. Microsc. Sci., 17(n.s.): 104-105. Antari, A. 1913. Zur Physiologie der Chlamydomonaden. Versuche und Beobachtungen an Chlamydomonas Ehrenbergii Gorosch. und verwandten Formen. Pringsh. Jahrb. f. Wiss. Bot., 52: 410-466. Arwipsson, TH. 1938. Ueber Asterocytis, Astrocystis und Asterocystis. Bot. Notiser, 1938: 190-192. Atkins, W. R. G. 1923. The phosphate content of fresh and salt waters in its relationship to the growth of the algal plankton. Jour. Marine Biol. Assoc., 18: 119-150. Arxins, W. R. G., and Harris, G. T. 1924. Seasonal changes in the water and heleoplankton of fresh-water ponds. Sci. Proc. Roy. Dublin Soc., 18(n. s.): 1-21 (reprint). Arxinson, G. F. 1890. Monograph of the Lemaneaceae of the United States. Ann. Bot., 4: 177-229; Pls. 7-9. 1931. Notes on the genus Lemanea in North America. Bot. Gaz., 92: 225-242. ATWELL, C. B. 1889. A deep-water Nostoc. Bot. Gaz., 14: 991-292. AvERINTZEV, S. 1899. Zur Kenntnis der Protozoen-Fauna in der Umgebung von Bologoje. Trav. Soc. Imp. Natur. St. Pétersb., 30, Lvr. 1, No. 6: 238-251. Bacu, E. B. 1907.* The Characeae of Michigan. Pap. Mich. Acad. Sci., Arts, and Letters, 9: 126. BacuMann, H. 1908. Vergleichende Studien iiber das Phytoplankton von Seen Schottlands und der Schweiz. Arch. f. Hydrobiol. u. Planktonk., 3: 1-91; Figs. 1-12, I-XI. 1911. Das Phytoplankton des Siisswassers mit besonderer [ 611 ] Beriicksichtigung des Vierwaldstittersees. Mitt. Naturf. Ges. Luzern, 6: 1-213. 1920. Merismopedia Trolleri Nov. Spec. Zeit. f. Hydrol., 1; 350. 1923. Charakterisierung der Plankton-vegetation des Vierwaldstattersees mittels Netzfangen und Zentrifugenproben. Mitt. Naturf. Ges. Basel, 35: 148-167. 1928. Das Phytoplankton der Pioraseen nebst einigen Beitragen zur Kenntnis des Phytoplanktons schweizerischer Alpenseen. Zeit. f. Hydrol., 4: 50-103. Baitey, J. W. 1841. A sketch of the infusoria, of the family Bacillaria, with some account of the most interesting species which have been found in a recent or fossil state in the United States. Amer. Jour. Sci. and Arts, 41: 284-305. 1847. Notes on the algae of the United States. Ibid., 3 (Ser. 2): 80-85, 399-403. 1848. Continuation of the list of localities of algae in the United States. Ibid., 3(Ser. 2): 37-42. 1851. Microscopical observations made in South Carolina, Georgia and Florida. Smiths. Contrib. Knowledge, 2(Art. 8): 1-48; Pls. 1-3. 1855. Notes on new species and localities of microscopical organisms. I—XIV. Ibid., 7, Art. 3: 1-15. Baker, W. B. 1926. Studies in the life history of Euglena. I. Euglena agilis Carter. Biol. Bull., 51: 321-362; Pls. 1,2, Figs. A, B. Batpwin, H. B., and Wuuepte, G. C. 1906. Observed relations between dis- solved oxygen, carbonic acid and algal growths in Weequahic Lake, N. J. Rep. Amer. Publ. Health Assoc., 32: 167-182. Bearps.ey, A. E. 1901. Notes on Colorado protozoa, with descriptions of new species. Trans. Amer. Microsc. Soc., 23: 49-59; PI. 11. Bennett, A. W. 1886. Freshwater algae (including chlorophyllaceous pro- tophyta) of the English Lake District; with descriptions of twelve new species. Jour. Roy. Microsc. Soc. 1886: 1-15. 1888. Fresh-water algae (including chlorophyllaceous protophyta) of the English Lake District. IL With descriptions of a new genus and five new species. Ibid., 1888: 1-6. 1890. Freshwater algae and Schizophyceae of Hampshire and Devonshire. Ibid., 1890: 1-10. 1892. Freshwater algae and Schizophyceae of South-west Surrey. Ibid., 1892: 4-12. Bercguist, S$. G. 1936. The Pleistocene history of the Tahquamenon and Man- istique drainage region of the northern Peninsula of Michigan. Mich. State Dept. Conserv., Publ. 40( Geol. Ser., 34): 1-137. BerkELEY, M. J. 1833. Gleanings of British algae; being an appendix to the supplement to English Botany. London. BERKELEY, M. J., and Harvey, W. H. 1855-1859. In J. D. Hooker. The botany of the antarctic voyage. Part HI. Flora Tasmaniae. BERNARD, C. 1908. Protococcacées et desmidiées d’eau douce récoltées 4 Java. Dépt. Agric. Ind. Néerland. Batavia. Pls. 1-16. 1909. Sur quelques algues unicellulaires d’eau douce récoltées dans le domaine Malais. Ibid., Buitenzorg. 1910. Algues d’eau douce. Nova Guinea, 8: 253-270. BERTHOLD, G. 1878. Untersuchungen iiber die Verzweigung einiger Siisswasser- algen. Nova Acta Acad. Caes. Leop.-Carol. Germ. Nat. Curiosorum, 40: 167-230; Pls. 1-4. BERTRAND, PauL. 1927. Les Botryococcacées actuelles et fossiles et les consé- quences de leur activité biologique. Comp. Rend. Soc. Biol., 96: 695-697. Bryerincx, M. W. 1890. Culturversuche mit Zoochlorellen, Lichenengonidien und anderen niederen Algen. Bot. Zeit., 48: 725-739, 741-754, 757-768, 781-785; Pl. 7. Buarapwaya, Y. 1933. False branching and sheath-structure in the Myxophy- ceae, with special reference to the Scytonemataceae. Arch. f. Protist., 81: 243-283; Figs. 1-9. 1933a. Contributions to our knowledge of the Myxo- phyceae of India. Ann. Bot., 47: 117-143. 1934. The taxonomy of Scytonema [ 612 | and Tolypothrix including some new records and new species from India and Ceylon. Rev. Algol., 7: 149-178. 1935. The Myxophyceae of the United Provinces, India. I. Proc. Indian Acad. Sci., 2( Sec. B.): 95-107. Bicearp, E. 1933.+ Les Pediastrum d'Europe. Etude biologique et systématiquc. Trav. Lab. Bot. Univ. Cathol. Angers, 5: 1-192. 1934-1936. Les Pediastrum d‘Europe. Etude biologique et systématique. Rev. Algol., 7: 1-94, 327-418. Birce, E. A. 1898. Plankton studies on Lake Mendota. II. Trans. Wis. Acad. Sci., Arts and Letters, 11: 274-448. Birce, E. A., and Jupay, C. 1911. The inland lakes of Wisconsin. The dissolved gases of the water and their biological significance. Bull. Wis. Geol. and Nat. Hist. Surv., Sci. Ser., 22: 1-259; Figs. 1-142. 1912. A limnological study of the Finger Lakes of New York. Bull. U. S. Bur. Fisheries, 32(Doc. No. 791): 525-609. 1914. The inland lakes of Wisconsin. The hydrography and mor- phometry of the lakes, by C. Juday. Bull. Wis. Geol. and Nat. Hist. Surv., Sci. Ser., 27: 1-137. 1922. The inland lakes of Wisconsin. The plankton. I. Its quantity and chemical composition. Ibid., 64(Sci. Ser. No. 13): 1-222. BisHop, AMELIA SAMANO. 1934. Contribucién al conocimiento de las algas verdes de los lagos del valle de México. Ann. Inst. Biol., 5(No. 2): 149-177; Pls. 1-3 (reprint ). ByevyaEva, A. I. 1922. De sectione Aegagropila Kiitz. generis Cladophorae Kiitz. et de nonnullis speciebus hujus sectionis in Rossia inventis. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 1( No. 6): 86-94. Buiackpurn, K. B. 1936. Botryococcus and the algal coals. Part I. A reinves- tigation of the alga Botryococcus Braunii Kiitzing. Trans. Roy. Soc. Edin- burgh, 58( pt. 3): 841-854. Biackman, F. F. 1900. The primitive algae and the flagellata. An account of modern work bearing on the evolution of the algae. Ann. Bot., 14: 647-688; Figs: 1, 2: pees F. F., and Tanstey, A. G. 1902. A revision of the classification of the green algae. New Phytol., 1: 17-24, 47-48, 67-72, 89-96, 114-120, 133-144, 163-168, 189-192, 213-220, 238-244. BLANCHARD, Frank N. 1913. Two new species of Stigonema. Rhodora, 15: 192-200; Pl. 105. Buu, J. R. 1943.* New species of Spirogyra. Amer. Jour. Bot., 30: 782-788; Figs. 1-11. poet nae: F. 1894. Ferskvandsalger fra Ostgrénland. Medd. om Gronland, 18: 3-41; Pls. 1, 2; Figs. 1,2. 1898. Nogle Ferskvandsalger fra Island. Bot. Tids., 22: 131-188. 1899. Conspectus algarum novarum aquae dulcis, quas in insulis Faeroensibus invenit. Vidensk. Medd. fra den Naturhist. Foren. i Kjobenhavn, 1899: 317-336. 1901. Freshwater algae. Botany of the Faeroes, Part I. pp. 198-259. Copenhagen. BoercEsEN, F., and OstenreLp, C. H. 1903. Phytoplankton of lakes in the Faerées. Botany of the Faerées, Part II. pp. 613-624; Figs. 147-150. Copen- hagen. poe Knut. 1897. Die Algen der ersten Regnell’schen Expedition. I. Pro- tococcoideen. Bih. Kongl. Sv. Vet.-Akad. Handl., 23, Afd. 3, No. 7: 8-47; Pls. 1,2. 1897a. Zur Morphologie und Biologie einzelliger Algen. Oefv. Kongl. Sv. Vet.-Akad. Férhandl., 1897(No. 9): 507-529; Figs. 1-10. 1897b. Studier 6fver niigra sligten af Alggruppen Confervales Borzi. Bih. Kongl. Sv. Vet.-Akad. Handl., 23, Afd. 3, No. 3: 1-56; Pls. 1, 2. 1901. Etude sur la flore algologique d’eau douce des Acores. Ibid., 27, Afd. 3, No. 4; 1-85; Pl. }. Boxp, H. C. 1931. Life history and cell structure of Chlorococcum infusionum. Bull. Torr. Bot. Club, 57: 577-604; Pls. 32-36, Figs. 1-5. [ 613 ] Botpt, R. 1885. Bidrag till kannedomen om Sibiriens Chlorophyllophycéer. Oefv. Kongl. Sv. Vet.-Akad. Forhandl., 42(No. 2): 91-128. 1893. Nagra sdtvattens-alger friin Gronland. Bot. Notiser, 1893: 156-158. BoLocuonzEw, E. 1903. Ueber das Phytoplankton einiger Seen im Rostowshen Kreise des Gouvernement Jaroslawe und zweier Seen des Gouvernement Wadimir. Jahrb. d. Biol. Walgastation Saratow, 1903: 251-269. Borce, O. 1891. Ett litet bidrag till Sibiriens Chlorophyllophycé-Flora. Bih. Kong]. Sv. Vet.-Akad. Handl., 17, Afd. 3, No. 2: 1-16. 1892. Chlorophyl- lophyceer fran Norska Finmarken. Ibid., 17, Afd. 3, No. 4: 3-15. 1894. Siisswasser-Chlorophyceen gesammelt von Dr. A. Osw, Kihlman im nérd- lichsten Russland, Gouvernement Archangel. Ibid., 19, Afd. 3, No. 5: 1-41. 1894a. Ueber die Rhizoidenbildung bei einigen fadenformigen Chlorophyceen. 61 pp., 2 pls. Upsala. 1895. Bidrag till kannedomen om Sveriges Chloro- phycéer. II. Chlorophyllophyceen aus Falbygden in Vestergétland. Bih. Kongl. Sv. Vet.-Akad. Handl., 21, Afd. 3, No. 6: 1-26. 1896. Australische Siisswasserchlorophyceen. Ibid., 22, Afd. 3, No. 9: 1-32. 1899. Ueber tropische und subtropische Siisswasser-Chlorophyceen. Ibid., 24, Afd. 3, No. 12: 1-33. 1900. Schwedisches Siisswasserplankton. Bot. Notiser, 1900: 1-26. 1901. Siisswasseralgen aus Siid-Patogonien. Bih. Kongl. Sv. Vet.-Akad. Handl., 27, Afd. 8, No. 10: 1-40; Pls. 1,2. 1906. Siisswasser-Chlorophyceen von Feuerland und Isla Desolacion. Bot. Stud. t. F. R. Kjellman, 1906: 21-34. 1907. Beitriige zur Algenflora von Schweden. Arkiv f. Bot., 6(1906), No. 1: 1-88. 1906. [1907]. Algen aus Argentina und Bolivia. Ibid., 6( 1907), No. 4: 1-13; Figs. 1-5. 1909.* Nordamerikanische Siisswasseralgen. Ibid., 8, No. 13: 1-29. 1913. Zygnemales, Spezieller Teil. In A. Pascher, Die Siisswassser- flora Deutschlands, Oesterreichs und der Schweiz, Heft 9: 12-51, Figs. 1-79; Jena. 1918a. Beitriige zur Algenflora von Schweden. 2. Die Algenflora um den Torne-Triisksee in Schwedisch-Lappland. Bot. Notiser, 1913: 1-82, 49-64, 97-110; Pls. 1-3; Figs. 1, 2. 1918 [1919]. Die von Dr. A. Lofgren in Sao Paulo gesammelten Siisswasseralgen. Arkiv £. sBots WaNos 13): 1-108; Pls. 1-8. 1921. Die Algenflora des Takernsees. Sjon Takerns Fauna och Flora. Kongl. Sv. Vet.-Akad., 1921(No. 4): 38-48; Pls. 1, 2; Figs. 1-3. 1922 [1923]. Beitrage zur Algenflora von Schweden. 3. Arkiv. f. Bot., 18(No. 10): 1-34; Pls. 1, 2; Figs. 1, 2. 1925. Die von Dr. F. C. Hoehne wahrend der Expedition Roosevelt-Rondon gesammelten Siisswasseralgen. Ibid., 19(No. 17): 1-56; Pls. 1-6; Figs. 1-3. 1928. Siisswasseralgen. In B. Schréeder, Zellpflanzen Ostafrikas, gesammelt auf der Akademischen Studien- fahrt 1910. Teil VIII. Hedwigia, 68: 93-114; Pls. 1, 2; Fig. 1. 1933. Schwedische-chinesische wissenschaftliche Expedition nach den nordwest- lichen Provinzen. Arkiv f. Bot., 25A(No. 17): 1-18. Borce, O., and Pascuer, A. 1913. (See Borge, 1913.) Bornet, E. 1889. Les Nostocacées hétérocystées du Systema Algarum de C. A. Agardh (1824) et leur synonymie actuelle (1889). Bull. Soc. Bot. France. 36: 144-157. Bornet, E., and Franautt, Cu. 1885. Note sur le genre Aulosira. Bull. Soc. Bot. France, 32: 119-122. 1885a. Tableau synoptique des Nostocacées filamenteuses hétérocystées. Mém. Soc. Nat. Sci. Nat. et Math. Cherbourg, 25: 195-223; Ibid., 26: 137-152. 1886.+ Révision des Nostocacées hétéro- cystées contenues dans ‘les principaux herbiers de France. Ann. Sci. Nat. Bot., 3(Sér. 7): 323-381. 1886a.+ Part IL., Ibid., 4 (Sér. 7): 343-373; 1887. Part III. Ibid., 5(Sér. 7): 51-129. 1888.+ Part IV. Ibid., 7(Sér. 7): 177-262. 1888a. Note sur deux nouveaux genres d’algues perforantes. Jour. Bot., 2: [ 614 ] 161-165. 1889. Sur quelques plantes vivant dans le test calcaire des mollusques. Bull. Soc. Bot. France, 36: cxtv-cLxxvi; Pls. 6-12. BorneT, E., and Tuuret, G. 1876-1880. Notes algologiques, recueil d’obser- vations sur les algues. Paris. Bory bE St. ViNcENT, J. B. 1808. Mémoire sur le genre Lemanea de la famille des Confervés. Ann. Mus. Hist. Nat. Paris, 12: 177-190. 1808a. Mémoire sur le genre Draparnaldia de la famille des Confervés. Ibid., 12: 399-409. 1822-1831. In Dictionnaire d’histoire naturelle. Paris. Borzi, A. 1878. Note alla morfologia e biologia delle alghe ficocromacee. Nuovo Giorn. Bot. Ital., 10: 236-288. 1879. Ibid., 11: 347-388. 1882. Ibid., 14: 272-315. 1883. Studi algologici. Fasc. 1: 1-112; Pls. 1-9. Messina. 1889. Botrydiopsis, nuova genre di alghe verdi. Boll. Soc. Ital. Microsc., 1: 66-70. 1892. Alghe d’acqua dolce della Papuasia raccolte su cranii umani dissepolti. Nuova Notarisia, 3(1892): 35-53. 1894. Studi algologici. Fasc. 2: 121-378; Pls. 10-31. Palermo. 1895. Probabili accenni di conjugazione presso alcune Nostochinee. Boll. Soc. Bot. Ital., 1895, No. 6: 208-210. 1914. Studi sulle Mixoficee. I. Nuovo Giorn. Bot. Ital., 21(n. s.): 307-360. 1916. Studi sulle Stigonemaceae. Ibid., 23(n.s.): 559-588. 1917. Ibid., 24(n.s.): 65-112. BourrELty, P., and FELDMANN, J. 1946. Une algue méconne: Sphaeroplea Soleirolii (Duby) Montagne. Bull. Mus. Paris, 18(No. 5): 412-415; Figs. 1-11. BoyE-PETERSEN, JOHN. 1923. The Botany of Iceland. Vol. 2, Part 2, No. 2: 249-324. Bracuer, R. 1919. Observations on Euglena deses. Ann. Bot., 33: 93-108. Branp, F. 1899. Mesogerron, eine neue Chlorophyceen-Gattung. Hedwigia, 38: [181-184]. 1899a. Cladophora-Studien. Bot. Centralbl., 79: 145-152, 177-186, 209-221, 287-311; Pls. 1-3. 1901. Ueber einige Verhiltnisse des Baues und Wachsthums von Cladophora. Beih. Bot. Centralbl., 10: 481-521; Figs. 1-10. 1902. Zur niheren Kenntnis der Algengattung Trentepohlia Mart. Ibid., 12: 200-205; Pl. 6. 1902a. Die Cladophora-Aegagropilen des Siisswassers. Hedwigia, 41: 34-71; 1 pl. 1905. Ueber die Anheftung der Cladophoraceae, und iiber verschiedene polynesische Formen dieser Familie. Beih. Bot. Centralbl., 18: 165-193. 1907. Ueber charakteristische Algen- Tinktionen, sowie iiber eine Gongrosira und eine Coleochaete aus dem Wiirmsee. Ber. d. Deutsch. Bot. Ges., 25; 497-506. 1908. Zur Morphologie und Biologie des Grenzgebietes zwischen den Algengattung Rhizoclonium und Cladophora. Hedwigia, 48: 45-73. 1909. Ueber die Siisswasserformen von Chantransia (DC.) Schmitz, einschliesslich Pseudochantransia Brand. Ibid., 49: 107-118. 1909a. Ueber die morphologischen Verhaltnisse der Cladophora-Basis. Ber. d. Deutsch. Bot. Ges., 27: 292-300. 1918. Ueber Cladophora humida n. sp., Rhizoclonium lapponicum n. sp., und deren bostrychoide Verzweigung. Hedwigia, 53: 179-183. Branp, F., and SrockMayeER, S. 1925. Analyse der aerophilen Griinalgenanfliige, insbesondere der proto-pleurococcoiden Formen. Arch. f. Protist., 52: 265- 855; Pl. 11. Branpt, K. 1882. Ueber die morphologische und physiologische Bedeutung des Chlorophylls bei Thieren. Arch. Anat. Physiol. Abth., Heft 1: 125-150. BRAUN, ALEXANDER. 1834. Esquisse monographique du genre Chara. Ann. Sci. Nat. Bot., 1(Sér. 2): 849-857. 1845. Additional notices of the North American Charae. In G. Englemann and A. Gray, Plantae Lindheimerianae. Boston Jour. Nat. Hist., 5: 264. 1847. Uebersicht der Schweizerischen Characeen. Neue Denkschr. d. Schweiz. Ges. d. Natur., 10: 1-23 (reprint, [ 615 ] 1849). 1849. In F. T. Kuetzing, Species algarum. 1851. Betrachtungen tiber die Erscheinung der Verjiingung in der Natur. Leipzig. 1855.+ Algarum unicellularum genera nova vel minus cognita. Pls. 1-6. Leipzig. 1856. Ueber Chytridium, eine Gattung einzelliger Schmarotzergewachse auf Algen und Infusorien, Abh. K. K. Akad. d. Wiss. z. Berlin, 1855: 21-83. 1865. In L. Rabenhorst. Florae Europaea algarum aquae dulcis et submarinae. 2. Leipzig. Braun, ALEXANDER, and Grunow, A. 1865. In L. Rabenhorst. F lorae Europaea algarum aquae dulcis et submarinae. 2. Leipzig. Brépisson, A. pe. 1844, Description de nouveaux genres d’algues fluviatiles. Ann. Sci. Nat. Bot., 1 (Ser. 3): 25-81. Pls. 1, 2. Brébisson, A. de, and Godey, P. 1835. Algues des environs de Falaise décrites et dessinées. pp. 1-66. Falaise. 1836. Ibid. Mém. Soc. Acad. sci. arts et bell. lettr. de Falaise Bot., 1835: 1-62, 266-269. BreHM, V. 1910. Ueber tropisches Siisswasserplankton. Die Kleinwelt, 1: 171-175. BRETSCHNEIDER, L. H. 1926. Ueber den feineren Bau von Phacus costata Conrad. Arch. f. Protist., 53: 131-134. BristoL, B. Muriev. 1920. A. review of the genus Chlorochytrium, Cohn. Jour. Linn. Soc. Bot. London, 45: 1-28; Pls. 1-3. 1920a. On the alga-flora of some desiccated English soils. Ann. Bot., 34: 35-80; Pl. 2. Britton, M. E. 1943. New species of Chlorophyceae. Amer. Jour. Bot., 30: 799-800; Figs. 1-3. Britron, M. E., and Smirn, B. H. 1942. A new species ef Spirogyra. Ohio Jour. Sci., 42; 70. Brown, C. J. D. 1943. How many lakes in Michigan? Mich. Conserv., 12(5)i: 6—7. Brown, HeLen Jean. 1929.+ The algal family Vaucheriaceae. Trans. Amer. Microsc. Soc., 48: 86-117; Pls. 15-20. 1937." A new species of Vaucheria from northern Michigan. Ibid., 56: 283-284; Fig. 1. Brown, W. H. 1909. The plant life of Ellis, Great, Little, and Long Lakes in North Carolina. Contrib. U. S. Nat. Herb., 13(1909-1913): 323-341. BrRUNEL, JULEs. 1932. Etudes sur la flora algologique du Québec. I. Contrib. Lab. Bot. Univ. Montreal, No. 22: 3-19; Figs. 1-3. 1947. Vaucheria Schlei- cheri in North America. Contrib. Gray Herb., 165: 62-69; Figs. 1, 2. BRUNNTHALER, J. 1901. Die koloniebildenden Dinobryon-Arten. Ver. Cae KG Zool.- Bot. Ges. in Wien, Math.-Nat. Kl1., 51: 293-306. 1903. Phytoplankton aus Kleinasien. Sitz. K. K. Akad. Wiss. Wien, Math.-Nat. Kl, 112(1902), Abt. 1: 289-293. 1907. Die Algen und Schizophyceen der Altwisser der Donau bei Wien. Ver. K. K. Zool.-Bot. Ges. Wien, Math.-Nat. Kl., 57: 170-223. 1912. Systematische Uebersicht iiber die Chlorophyceen-Gattung Scenedesmus Meyen. Hedwigia, 53: 164-172. 1913. Die Algengattung Radiofilum Schmidle und ihre systematische Stellung. Oesterr. Bot. Zeit., 63(No. 1): 1-8; Figs. 1-3. 1914. Beitrag zur Siisswasser-Algenflora von Aegypten. Hedwigia, 54: 919-225. 1915.+ Protococcales. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 5. Chloro- phyceae 2: 52-205; Figs. 1-330. Jena. Bucuanan, R. E. 1907. Notes on the algae of Iowa. Proc. Iowa Acad. Sci., 14: 47-84. Buppve, H. 1940. Beitrige zur Kenntnis der bayerischen Batrachospermum- Arten aus der Umgebung von Tolz. Ber. Bayr. Bot. Ges., 24: 87-94. Buri, HEeLen F. 1938. The taxonomy of a community of blue-green algae in a Minnesota pond. Bull. Torr. Bot. Club, 65: 377-396; Figs. 1-12. Buerscuui, O. 1878. Beitrige zur Kenntnis der Flagellaten und einiger ver- wandter Organismen. Zeit. f. Wiss. Zool., 30: 205-281. 1883-1887. Masti- [ 616 ] gophora, Protozoa. In H. G. Bronn, Klassen und Ordnungen des Tier-Reiches, 1, Abt. 2; Pls. 39-55. Leipzig and Heidelberg. BURKHOLDER, Paut R. 1930. Microplankton studies of Lake Erie. Bull. Buffalo Soc. Nat. Sci., 14: 73-91. 1931. Studies in the phytoplankton of the Cayuga Lake basin, New York. Ibid., 15: 21-179. Burr, Geo. O. 1941. Photosynthesis of algae and other aquatic plants. In A Symposium on Hydrobiology, Madison. Carxins, G. N. 1892. On Uroglena, a genus of colony-building infusoria ob- served in certain water supplies of Massachusetts. 23rd Ann. Rep. State Bd. of Health, Mass., 1892: 647-657; Pls. 1-4. 1926. Biology of the Protozoa. New York. CampsELL, D. H. 1886.* Plants of the Detroit River. Bull. Torr. Bot. Club, 13: 93-94. Carter, Neuuie. 1919. On the cytology of two species of Characiopsis. New Phytol., 18: 177-186; Figs. 1-3. Carter, H. J. 1856. Notes on the freshwater infusoria of the Island of Bom- bay. No. 1. Organization. Ann. and Mag. Nat. Hist., 18(Ser. 2): 115-132, 221-249. 1859. On fecundation in the two Volvoces, etc. on Eudorina Spongilla, Astasia, Euglena and Cryptoglena. Ibid., 3( Ser. 3): 1-20. - CavanaucH, W. J., and TiLpEN, JOSEPHINE. 1930. Algal food, feeding and case-building habits of the larva of the midge fly, Tanytarsus dissimilis. Ecology, 11: 281-287. Cavers, F. 1913. Recent work on flagellata and primitive algae. New Phytol, 12: 28-36, 78-83, 107-123, 177-187, 225-232; Figs. 1-10. CEDERCREUTZ, Cart. 1924. Finnlaindische Zygnemalen. Acta Soc. Fauna et Flora Fenn., 55(No. 2): 1-7. 1931. Zwei neue Heterokontenarten. Arch. f. Protist., 75: 517-522. 1934. Die Algenflora und Algen-vegetation auf Aland. Acta Bot. Fenn., 15: 1-120; Pls. 1-5; 2 maps. CEDERGREN, G. R. 1926. Beitrage zur Kenntnis der Siisswasseralgen in Schwe- den. II. Die Algen aus Bergslagen und Wiasterdalarne. Bot. Notiser, 1926: 289-313. 1932. Die Algenflora der Provinz Harjedalen. Arkiv f. Bot., 25A(No. 4): 1-107. Cuaperaup, M. 1938. Nouvelle recherches sur l’anatomie comparée des Eugleniens: les Peranémines. Rev. Algol., 11: 189-220. Cuamsers, C. O. 1912. The relation of algae to dissolved oxygen and carbon dioxide, with special reference to carbonates. 23rd Ann. Rep. Missouri Bot. Gard., 1912: 171-207. CHANDLER, D. C. 1937. Fate of typical lake plankton in streams. Ecol. Monogr., 7: 445-479, 1939.* Plankton entering the Huron River from Portage and Base Line Lakes, Michigan. Trans. Amer. Microsc. Soc., 58: 24-41. 1944. Limnological studies of western Lake Erie. IV. Ibid., 63: 203-236. Cuapman, F. B. 1934. The algae of the Urbana (Ohio) raised bog. Ohio Jour. Sci., 834: 327-332. Cuapman, V. J. 1941. An introduction to the study of algae. New York. 1943. The aims of future research in the algae. Farlowia, 1: 5-8. CumirLewsx1, V. 1890. Matériaux pour servir 4 la flora des algues du governe- ment de Kharkow. Trav. Soc. Nat. Univ. Imp. Kharkow, 23: 79-105. Cuopat, R. 1894. Golenkinia, genre nouveau des Protococcoidées. Jour. Bot., 8: 305-308. 1894a. Matériaux pour servir a histoire des Protococcoideées. Bull. Herb. Boiss., 2: 585-616; Pls. 22-29. 1894b. Algues des environs de Genéve. Comp. Rend. Soc. Phys. et Hist. Nat. Genéve, In Arch. Sci. Phys. et Nat., 32: 623-625. 1895. Sur le genre Lagerheimia. Nuova Notarisia, 6: 86-90. 1895a. Matériaux pour servir 4 histoire des Protococcoidées. II. Bull. [ 617 ] Herb. Boiss., 3: 109-114. 1895b. Ueber die Entwickelung der Eremosphaera viridis de By. Bot. Zeit., 53: 137-142; Pl. 5. 1896. Sur la structure et la biologie de deux algues pélagiques. Jour. Bot., 10: 333-349, 405-408; PI. 3. 1897. Algues pélagiques nouvelles. Bull. Herb. Boiss., 5: 119-120. 1897a. Etudes de biologie lacustre. A. Recherches sur les algues pélagiques de quelques lacs suisses et frangais. Ibid., 5: 289-314. 1898. Etudes de biologie lacustre. B. Nouvelles remarques sur la flore pélagique superficielle des lacs suisses et francais. Ibid., 6: 49-77, 155-188. 1898a. Etudes de biologie lacustre. C. Recherches sur les algues littorales. Ibid., 6: 431-475; Pls. 14, 15. 1900. Sur trois genres nouxeaux de Protococcoidées et sur la florule planktonique d’un étang du Danemark. Mém. Herb. Boiss., 1(No. 17): 1-10; Figs. 1-20. 1902. Algues vertes de la suisse. Pleurococcoides-Chroolépoides. Matér. pour la Flore Crypt. Suisse, 1(No. 3): 1-373; Figs. 1-264. 1918. Monographie d’algues en culture pure. Ibid., 4(Fasc. 2): 1-226; Pls. 1-9. 1919. Sur un Glaucocystis et sa position systématique. Bull. Soc. Bot. Genéve, 11: 42-49; Figs. 1,2. 1921. Matériaux pour histoire des algues de la Suisse. I-IX. Ibid., 13: 66-114. 1926.+ Scenedesmus. Etude de genetique, de systématique expérimentale et d’hydrobiologie. Rev. d’Hydrol., 3: 71-258; Figs. 1-162. Cuopat, R., and Cuopat, F. 1925. Esquisse planctologique de quelques lacs francais. Festschr. Carl Schroter, 3: 436-459; Figs. 1-14. Cuopat, R., and Grinrzesco, J. 1900. Cultures pure d’algues Protococcacées. Comp. Rend. Soc. Phys. et Hist. Nat. Genéve, in Arch. Sci. Phys. et Nat., 10: 386-387. Crenxowsk1, L. 1855. Algologische Studien. 2. Protococcus botryoides Kuetz. Bot. Zeit., 13: 780-782; Pl. 11. 1865. Ueber einige chlorophyllhaltige Gloeocapsen. Ibid., 23(No. 8): 21-27; Pl. 1. 1870. Ueber Palmellaceen und einige Flagellaten. Archiv f. Mikro. Anat., 6: 421-438; Pls. 23,24. 1876: Zur Morphologie der Ulothricheen. Bull. Acad. Imp. Sci. St. Péters. 21: 529-557; Pls. 1, 2. 1881. [Algologische excursion an das Weiss Meer]. Arb. d. Kais, St. Petersb. Ges. d. Naturf., 12: 130-171. Cuarke, G. L., and Getuis, S. S. 1935. The nutrition of copepods in relation to the food cycle of the sea. Biol. Bull., 68: 231-246. CLAPAREDE, Ep., and LacuMann, J. 1857-1861. Etudes sur les infusiores et les rhizopodes. Mém. Instit. Nat. Genevois, 5( 1858): 1-260; Ibid., 6(1860): 261—482.; Ibid., 7( 1861): 1-291. Creve, P. T. 1868. Férsok till en monografi éfver de Svenska arterna af Algfamiljen Zygnemaceae. Nova Acta Reg. Soc. Sci. Upsala, 6(Ser. 3), No. 11: 1-88. Cocuran, L. C. 1932.* A thermophilic Calothrix in Michigan. Pap. Mich. Acad. Sci., Arts, and Letters, 15: 63-64. Coun, F. [1852]. Ueber eine neue Gattung aus der Familie des Volvocinen. Zeit. f. Wiss. Zool., 4: 77-116. 1856. Mémoire sur le développement et Je mode de reproduction du Sphaeroplea annulina. Ann. Sci. Nat. Bot., 5(Sér. 4): 187-208; Pls. 12, 13. 1875. Ueber parasitische Algen. Beitr. Biol. Pflan- zen, 1(No. 2): 87-108. 1875a. Die Entwickelungsgeschichte der Gattung Volvox. Ibid., 1(No. 8): 93-115; Pl. 2. Coun, F., and Wicuura, M. 1858. Ueber Stephanosphaera pluvialis. Nova Acta Caes. Leop.-Carol. Germ. Nat. Curiosorum, 26: 1-BPe TAS, 15 BA Coxer, W. C. 1919. A parasitic blue-green alga. Jour. Elisha Mitchell Sci. Soc., 35:9. Co.uins, F. S. 1896. New Cyanophyceae. Erythea, 4: 119-121. 1897. Some perforating and other algae on fresh water shells. Ihid.. 5: 95-97. 1899. [ 618 ] Notes on algae. I. Rhodora, 1: 9-11. 1901. Ibid. Ill. Ibid., 3: 132-137. 1904. Algae of the flume. Ibid., 6: 229-231. 1905. Chlorochytrium Lemnae in North America. Ibid., 7: 97-99. 1907. Some new green algae. Ibid., 9: 197-202. 1909.+* The green algae of North America. Tufts College Studies, Sci. Ser., 2: 79-480, Pls. 1-18 (reprinted and repaged by G. E. Stechert, New York, 1928). 1912.+* The green algae of North America. Supplementary Paper. Ibid., 3(No. 2): 69-109; Pls. 1, 2 (reprinted by G. E. Stechert, New York, 1928). 1918.+ Notes from the Woods Hole Laboratory. Rhodora, 20: 141-143. 1918a.t The green algae of North America, 2nd Suppl. Tufts College Studies, Sci. Ser., 4: 1-106; Pls. 1-3 (reprinted by G. E. Stechert, New York, 1928). Comenre, J. 1911. Additions a la flore des algues d’eau douce du pays toulousain et des Pyrénées centrales. Bull. Soc. d’Hist. Nat. Toulouse, 44: 9-60. Conn, H. W., and Wesster, Lucia W. 1908. A preliminary report on the algae of the fresh waters of Connecticut. Conn. State Geol. and Nat. Hist. Surv., Bull. 10: 1-78; Pls. 1-44. Conran, W. 1913. Errerella bornhemiensis nov. gen., une Protococcacée nou- velle. Bull. Soc. Roy. Bot. Belgique, 52: 237-242; Figs. 1-3. 1914. Contri- butions a l’étude des flagellates. I. Arch. f. Protist., 34: 79-94. 1914a. Algues, Schizophycées et flagellates récoltés par M. W. Reckert aux environs de Libau (Courlande, Russie). Ann. Biol. Lacustre, 7: 126-152. 1916. Revision des espéces indigénes et frangaises du genre Trachelomonas Ehrenbg. Ibid., 8: 193-212. 1920. Contributions 4 T’étude des Chrysomonadines. Acad. Roy. Belgique, Cl. des Sci., 1920: 167-189; Figs. 1-11. 1922. Contributions a étude des Chrysomonadines. Rec. Inst. Léo Errera, 10: 333-353; Figs. 1-11. 1926. Recherches sur les flagellates de nos eaux saumatres. 2. Chrysomonadines. Arch. f. Protist., 56: 167-231. 1927. Essai d'une monographie des genre Mallomonas Perty (1852) et Pseudomallomonas Chodat (1920). Ibid., 59: 423-505; Pls. 8-11. 1932. Flagellates nou- veaux ou peu connus. III (Formes nouvelles du genre Trachelomonas Ehrbg.). Ibid., 78: 463-472. 1933.+ Révision du genre Mallomonas Perty (1851) incl. Pseudo-Mallomonas Chodat (1920). Mém. Mus. Roy. d’Hist. Nat. de Belgique, 56: 1-82; Figs. 1-70. 1934.+ Matériaux pour une mono- graphie du genre Lepocinclis Perty. Arch. f. Protist., 82: 203-249. 1934a. Euglenacées nouvelles ou peu connues. Ann. Protist., 4: 171-180. 1935.+ Etude systématique du genre Lepocinclis Perty. Mém. Mus. Roy. d'Hist. Nat. Belgique, 1(Sér. 2): 1-84. 1940. Notes protistologiques. 15. Sur une Euglena du psammon de Iescaut. Bull. Mus. Roy. Hist. Nat. Belgique, 16(No. 29): 1-12. 1940a. Notes protistologiques. 16. Sur Peridinium Woloszynskae n. sp. Ibid., 16(No. 32): 1-8. Conran, W., and Kurreratu, H. 1912. Addition a la flore algologique de la Belgique. Bull. Soc. Roy. Bot. Belgique, 49(Pt. 1): 293-335. Cooxe, M. E. 1882-1884.+ British freshwater algae, exclusive of Desmidieae and Diatomaceae. 329 pp.; Pls. 1-130. London. Corpa, A. J. C. 1835-1839. Observations sur les animalicules microscopiques, won trouve auprés des eau thermales de Carlsbad. Almanach de Carlsbad, 1835-1839. Correns, C. 1893. Ueber Apiocystis Brauniana Naeg. In A. Zimmermann, Beitr. z. Pflanzenzelle. 1( Heft 3): 241-259; Figs. 1, 2. Couey, Faye M. 1935.* Fish food studies of a number of northwestern Wis- consin lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 29: 131-172. Coyie, ExizaBetu. 1930. The algal food of Pimephales promelas. (Fathead minnow). Ohio Jour. Sci., 30: 23-25. [ 619 ] Cramer, C. E. 1859. Oedogonium Pringsheimii Cramer. Hedwigia, 2: 17-19. CroAsDALE, Hannay T. 1935. The fresh water algae of Woods Hole, Mass- achusetts. 134 pp.; Pls. I-VII; maps. Philadelphia. Crow, W. B. 1922. A critical study of certain unicellular Cyanophyceae from the point of view of their evolution. New Phytol., 21: 81-102; Fig. 1. 1923. Fresh-water plankton algae from Ceylon. Jour. Bot., 61: 110-114, 138-145, 164-171. 1924. Variation and species in Cyanophyceae. Jour. Genetics, 14: 397-424; Figs. 1-8. 1924a. Some features of the envelope in Coelastrum. Ann. Bot., 38: 398-401; Figs. A, B. 1925. The reproductive differentiation of colonies in Chlamydomonadales. New Phytol., 24: 120-123. 1927. The generic characters of Arthrospira and Spirulina. Trans. Amer. Microsc. Soc., 46: 139-148. 1927a. Abnormal forms of Gonium. Ann. and Mag. Nat. Hist., 19(Ser. 9): 593-601; Figs. A-G. 1928. The morphology of the filaments of Cyanophyceae. Ann. Protist., 1: 19-36. Curtis, J. T., and Jupay, C. 1937.* Photosynthesis of algae in Wisconsin lakes. III. Observations in 1935. Inter. Rev. Ges. Hydrobiol., 35: 122-133; Figs. , 2: Tab. 1-2: Czurpa, V. 1932.+ Zygnemales. In A. Pascher, Die Siisswasserflora Mitteleu- ropas, Oesterreichs und der Schweiz. Heft 9: 1-232; Figs. 1-226. Jena. 1939. Zygnemales der Deutschen Limnologischen Sunda-expedition. Archiv. f. Hydrobiol. Suppl., 16: 398-427. Da Cunna, A. M. 1913. Contribuigao para o conhecimento da fauna de pro- tozoarios do Brasil. Mem. Inst. Oswaldo Cruz, 5: 101-122. 1914. Beitrag zur Kenntnis der Protozoen-fauna Brasiliens. II. Ibid., 6: 169-175. Dapay, F. 1907. Plankton-Tiere aus dem Victoria Nyanza. Sammelausbeute von A. Bogert, 1904-1905. Zool. Jahrb. Abt. System, 25( Heft 2): 245-262. Dairy, Fay K. 1944. The Characeae of Nebraska. Butler Univ. Bot. Studies, 6: 149-171; Figs. 1A-5C. 1946. Species of Tolypella in Nebraska. Ibid., 8: 1138-116; Figs. 1A-1C. Dairy, WM. A. 1938. A quantitative study of the phytoplankton of Lake Michigan collected in the vicinity of Evanston, II]. Butler Univ. Bot. Studies, 4: 65-83. 1942. The Chroococcaceae of Ohio, Kentucky, and Indiana. Amer. Midl. Nat., 27: 636-661; Pls. 1-6. Damann, K. E. 1938. Quantitative study of the phytoplankton of Lake Mich- igan at Evanston, Illinois. Butler Univ. Bot. Studies, 5: 27-44. DancEarp, P. A. 1888. Recherches sur les algues inférieures. Ann. Sci. Nat. Bot., 7(Sér. 7): 105-175; Pls. 11, 12. 1889. Recherches sur les Cryptomona- dinae et les Euglenae. Le Botaniste, 1: 1-38. 1889a. Mémoire sur les algues. Ibid., 1: 127-174;Pls. 6,7. 1899. Mémoire sur les Chlamydomonadinées ou histoire d’une cellule. Jbid., 6: 65-290; Figs. 1-19. 1900. Observations sur le développement du Pandorina morum. Ibid., 7: 192-211; Pl. 5. 1901. Etude sur la structure de la cellule et ses fonctions, le Polytoma uvella. Ibid., 8: 5-58; Figs. 1-4. 1902. Recherches sur les Eugléniens. Ibid., 8(1901): 97-360. 1911. Un nouveau genre d’algues. Bull. Soc. Bot. France, 58: 309-311. 1912. Recii2rches sur quelques algues nouvelles ou peu connues. Le Botaniste, 12: I-XIX; Pls. 1,2. 1938. Mémoire sur la famille des Péri- diniens. Ibid., 29: 1-180. 1939. Le genre Vaucheria, spécialement dans la région du sud-ouest de la France. Ibid., 29: 183-264. 1939a. Second mémoire sur la famille des Péridiniens. Ibid., 29: 267-808. 1939b. Sur les algues Vaucheria observées dans la région du sud-ouest et sur une nouvelle espéce de ce genre. Comp. Rend. Acad. Sci. Paris, 208: 297-299. Davis, B. M. 1894. Euglenopsis, a new alga-like organism. Ann. Bot., 8: 877- [ 620 ] 390; Pl. 19. 1896. The fertilization of Batrachospermum. Ibid., 10: 49-76; Pls. 6,7. 1904. Oogenesis in Vaucheria. Bot. Gaz., 38: 81-98; Pls. 6, 7. Davis, C. A. 1900.* A contribution to the natural history of marl. Jour. Geol., 8: 485-497. 1908. The flora. A biological survey of Walnut Lake, Michigan. Ann. Rep. Mich. Geol. Surv., 1907: 217-231. Dr, P. K. 1939. The réle of blue-green algae in nitrogen fixation in rice fields. Proc. Roy. Soc. London (B), 127: 121-139. DeBary, A. A. 1854. Ueber die Algengattungen Oedogonium und Bulbochaete. Abh. Senck. Nat. Ges. Frankfurt A. M., 1: 29-105. 1858. Untersuchungen iiber die Familie der Conjugaten (Zygnemeen u. Desmidieen). 91 pp.; Pls. 1-8. Leipzig. DeCanpotte, A. P. 1802. Rapport sur les Conferves. Jour. de Phys. et Chimie et d’Hist. Nat., 54: 421-441. 1805. Flore Francaise, II. 3rd ed. Paris. Drr.anpreE, G. 1924. Additions 4 la flore algologique des environs de Paris. II.—Flagellées. Bull. Soc. Bot. France, 71: 1115-1180. 1924a. A propos de Euglena acus Ehrenb. Rev. Algol., 1: 235-243. 1926.+ Monographie du genre Trachelomonas. Pls. 1-15. Nemours. 1926a. Contribution a la flore algologique de la Basse-Normandie. Bull. Soc. Bot. France, 73: 701-717. 1926b. Algues d’eau douce du Vénézuela (Flagellées et Chlorophycées ) récoltées par la Mission M. Grisol. Rev. Algol., 3: 211-241. 1927. Remarques sur la systématique du genre Trachelomonas Ehr. I. Bull. Soc. Bot. France, 74: 285-288. Ibid. Il. Quarte Trachelomonas nouveaux. Ibid.: 657-665. 1930. Strobomonas, nouveau genre d’Euglenacées (Trachelomonas Ehrb. pro parte). Archiv f. Protist., 69: 551-614. 1932. Contributions 4 la con- naissance des Flagellés libres. I. Ann. Protist., 3: 219-239. De Lacerpa, F. S. 1946. Oedogoniaceae de Portugal. Portugal Acta Biol., 11(Ser. B): 1-142; Figs. I-LXVIII. Denis, M., and Fremy, P. 1923. Une nouvelle Cyanophycée heterocystée Anabaena Viguieri. Bull. Soc. Linn. Normandie, 6(Sér. 7): 122-125. Denniston, R. H. 1921.* A survey of the larger aquatic plants of Lake Men- dota. Trans. Wis. Acad. Sci., Arts, and Letters, 20: 495-500. Densés, A., and Soxser, A. J. J. 1850. Sur les organes reproducteurs des algues. Ann. Sci. Nat. Bot., 4(Sér. 3): 261-282. 1856. Mémoire sur quelques points de la physiologie des algues. Paris. Desmazizres, J. B. H. J. 1823. Catalogue des plantes omises dans la botano- graphie belgique. Lille. 1825-1860. Plantes cryptogames de France. Ed. , Fase. 144 (1825-1836). Ed. II, Fasc. 1-37 (1836-1851). Ed. Novae. Fasc. 1-16 (1853-1860). Lille. Desvaux, A. N. 1818. Observations sur les plantes environs de Angers. Paris. DeTon1, G. B. 1889.+ Sylloge algarum omnium hucusque cognitarum. I. Padua. 1907. Ibid. Myxophyceae. V. (A. Forti). Padua. De Tont, G. B., and Fort, A. 1899-1900. Contributo alla conoscenza del planc- ton del Lago Vetter. Atti Reale Istit. Veneto Sci., Lett. ed Arti, 59: 537-561, 779-829. (Note: pages 537-561 erroneously occur twice in Vol. 59. The citation refers to the first series of these pages. ) DeETont, G. B., and Saccarpo, Fr. 1890. Revisione de alcuni generi di Cloro- ficee epifite. Nuova Notarisia, 1: 3-20. De WitpeMann, E. 1888. Observations algologiques. Bull. Soc. Roy. Bot. Belgique, 27: 71-80 bis. 1892. Quelques mots sur le genre Scenedesmus Turpin. Ibid., 31(Pt. 2): 218-224. 1893. Le genre Scenedesmus Meyen. Notarisia, 1893: 85-106. 1893a. Contribution a l’étude des algues de Bel- gique. Ibid., 32(Pt. 2): 88-101. 1895. Le genre Palmodictyon Nag. Bull. [ 621 ] Herb. Boiss., 3: 328-333. 1897. Encore le Pleurococcus nimbatus de Wild. Ibid., 5: 582. Diesinc, K. M. 1866. Revision der Prothelminthen. Abtheilung Mastigophoren. Sitz. K. K. Akad. Wiss. Wein, Math.-Nat. K]., 52(1865), Abt. 1: 287-401. Dit, O. 1895. Die Gattung Chlamydomonas und ihre nachsten Verwandten. Pringsh. Jahrb. f. Wiss. Bot., 28: 323-358; Pl. 5. Dittwyn, F. 1802. British conjugates. London . Driwatp, Kar. 1989. Ein Beitrag zur Variabilitét und Systematik der Gattung Peridinium. Arch. f. Protist., 93: 121-148. Dortein, F. 1916. Lehrbuch der Protozoenkunde. IV. Auflage. Jena. 1921. Mitteilungen iiber Chrysomonadinen aus dem Schwarzwald. Zool. Anz., 53: 153-173; Figs. 1-4. 1922. Untersuchungen iiber Chrysomonadinen. Arch. f. Protist., 44: 149-213. 1923. Untersuchungen tiber Chrysomonadinen. III. Arten von Chromulina und Ochromonas aus dem Badischen Schwarzwald und ihre Cystenbildung. Ibid., 46: 267-327; Pls. 15-21. Figs. A-E. Dottey, Joun S. 1933.* Preliminary notes on the biology of the St. Joseph River. Amer. Midl. Nat., 14: 193-227. Domocatta, B. P. 1926.* Treatment of algae and weeds in lakes at Madison, Wisconsin. Eng. News Record, Dec. 9, 1926: 950-954. 1935.* Eleven years of chemical treatment of the Madison lakes: its effect on fish and fish foods. Trans. Amer. Fish. Soc., 65: 115-120. Domoca..a, B. P., and Frep, E. B. 1926. Ammonia and nitrate studies of lakes near Madison, Wisconsin. Jour. Amer. Soc. Agronomy, 18: 897-911. Dorocostaisky, V. 1905. Matériaux pour servir a l’algologie du lac Baikal et de son bassin. Bull. Soc. Imp. Nat. Moscou, 1904(No. 2/3): 228-265. DreEZEPOLSKi, R. 1923. De Eugleninis se ipsis sustinentibus ex collectione facta a Dr. J. Grochmalicki in Podlachi et Lithuania. Obd. z Rozpraw i wradomosci z Muzeum im Dzied, 7/8(1922): 1-19. 1925. Przyeznek do znajomosci polskich Euglenin. (Supplément a la connaissance des Eugléniens de la Pologne.) “Kosmos,” Jour. Soc. ,Polonaise Nar. “Kopernik,” 50(Fasc. 1.A): 173-270; Pls. 1-6. Drover, F. 1937. The Brazilian Myxophyceae. I. Amer. Jour. Bot., 24: 598- 608; Figs. 1-5. 1938. Ibid. Il. Ibid., 25: 657-666. 1938a. The Oscillatoriaceae of southern Massachusetts. Rhodora, 40: 221-241, 255-278. 1939. Francis Wolle’s filamentous Myxophyceae. Field Mus. Bot. Ser., 20: 17-64; Fig. 1. 1939a. The Myxophyceae of Maryland. Ibid., 20: 3-14. 1942. Studies in Myxophyceae. I. Ibid., 20: 125-141. 1943. New species of Oscillatoriaceae. Amer. Midl. Nat., 29: 51-54. Drovet, F., and Coun, A. 1935. The morphology of Gonyostomum semen from Woods Hole, Massachusetts. Biol. Bull., 68: 422-439. 1937. Further observations on Gonyostomum semen. Bot. Gaz., 98: 617-618. Drovet, F., and Damty, WM. A. 1939. The planktonic freshwater species of Microcystis. Field Mus. Bot. Ser., 20: 67-83. Duyarpin, M. F. 1841. Histoire naturelle des Zoophytes. Infusiores, compre- nant la physiologie et la classification de ces animaux et la maniére de les estudier 4 l'aide du microscope. In Suites a Buffon. Paris. Dutton, H. J. 1941. The chromatographic adsorption of plant pigments as a limnological method. In A Symposium on Hydrobiology. Madison. Dutton, H. J., and Mannine, W. M. 1941. Evidence for carotenoid-sensitized photosynthesis in the diatom Nitzschia Closterium. Amer. Jour. Bot., 28; 516-526. Eppy, SAMUEL. 1927.* The plankton of Lake Michigan. Ill. Nat. Hist. Surv., 17: [ 622 } 203-232. 1930.+ The fresh-water armored or thecate Dinoflagellates. Trans. Amer. Microsc. Soc., 49: 277-321; Pls. 28-35. Epmonpson, C. H. 1906. The Protozoa of Iowa. Proc. Davenport Acad. Sci., 11: 1-124; Pls. 1-30. EccLeTon, F. E. 1939. Réle of the bottom fauna in the productivity of lakes. In Problems of lake biology. Amer. Assoc. Adv. Sci., Publ. No. 10: 123-181. 1939a. Freshwater communities. Amer. Mid]. Nat., 21: 56-74. EHRENBERG, C. G. 1832. Die geographische Verbreitung der Infusionthierchen in Nord-Afrika und West Asien. Abh. d. Phys. Kl. Konig]. Akad. Wiss. z. Berlin, 1829: 1-20. 1832a. Beitrige zur Kenntniss der Organisation der In- fusorien und ihre geographische Verbreitung besonders in Sibirien. Abh. d. Kéngl. Akad. Wiss. z. Berlin, 1830: 1-88. 1832b. Ueber die Entwicklung und Lebensdauer der Infusionsthiere; nebst ferneren Beitragen zu einer Verglei- chung ihrer organischen Systeme. Phys. Abh. K6nigl. Akad. Wiss. z. Berlin, 1831: 1-154. 1835. Dritter Beitrag zur Erkenntniss grosser Organisation in der Richtung des kleinsten Raumes. Abh. d. Konigl. Akad. Wiss. z. Berlin, 1833: 145-336. 1837. Zusatze zur Erkenntniss grosser organischer Aus- bildung in den kKleinsten thierischen Organismen. Ibid., 1835: 151-180. 1838. Die Infusionsthierchen als vollkommene Organismen. Leipzig. 1849. Beo- bachtung zweier generisch neuer Formen der Friihlingsgewassers bei Berlin. Monatsber. Konig]. Akad. Wiss. z. Berlin, 1848: 233-247. Ercuwa.p, V. 1847. Erster Nachtrag zur Infusorienkunde Russlands. Bull. Soc. Imp. Nat. Moscou, 20: 285-366. 1849. Ibid., 2. Ibid., 22: 400-548. 1852. Ibid. 3. Ibid., 25: 388-536. Exenxin, A. A. 1909. Neue, seltene oder interessante Arten und Formen der Algen in Mittel-Russland 1908-1909 gesammelt. Bull. Jard. Imp. Bot. Pierre le Grand, 9(No. 6): 121-154. 1915. [Note sur une algue nouvelle Leptobasis caucasica mihi (nov. gen. et sp.) suivé de la révision critique de genre Microchaete Thur.] Ibid., 15(No. 1): 5-22. 1922. Calothrix Ramenskii mihi nov. sp. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 1(No. 1): 6-9. 1922a. De nova specie Aulosirae notula. Ibid., 1(No. 8): 127-128. 1923. De Chroococcacearum classificatione notula. Ibid., 2(No. 4): 49-62. 1923a. Schema Chroococcacearum classificationis. Ibid., 2(No. 5): 65-69. 1923b. De gen. Anabaenopsis (Woloszynska ) Miller notula. Ibid., 2(No. 5): 73-78. 1924. De spec. duabus gen. Microcystis Kiitz. notula. Ibid., 3( No. 1): 12-15. 1924a. Descriptio specierum formarumque novarum e gen. Characium A. Braun et Characiopsis Borzi cum Crustaceis symbioticis. Ibid., 3( No. 8): 33-36. 1924b. De Euglenarum sine flagello sectione nova. I-II. Ibid., 8(No. 9/10): 129-160. Evenxin, A. A., and Hotiersacu, M. M. 1923. De Coelosphaerio Naegeliano Unger nonnullisque speciebus hujus generis et de Gomphosphaeria Kuetz. notula. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 2(No. 10): 145-155. 1923a. Schema specierum gen. Gomphosphaeriae Kuetz. et Coelosphaerii (Naeg.) nob. emend. Ibid., 2(No. 10): 155-157. Evenxin, A. A., and Ont, Lypia. 1926. Die Fortschutte der floristischen algologie in USSR wahrend der letzten 25 Jahre. Ver. Inter. Vereinig. f. Theoret. u. Angew. Limnol., 3: 166-177. Evenxin, A. A., and Starx, N. V. 1923. De Asterocyti ramosa (Thwait) Gobi caeterisque speciebus hujus generis notula. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 2(No. 8): 117-128. E-Nayat, A. A. 1935. Egyptian freshwater algae. Egyptian Univ. Bull. Fac. Sci., No. 4: 1-106; Figs. 1-143. 1939. On some new freshwater algae from Egypt. Rev. Algol., 8: 311-319. [ 623 ] Entz, G. 1909. Ueber die Organisationsverhiltnisse Peridineen. Math.-Natur. Berichte aus Ungarn, 25(1907): 246-274. 1926. Beitrage zur Kenntnis der Peridineen. I. Zur Morphologie und Biologie von Peridinium Borgei Lem- mermann. Arch. f. Protist., 56: 397-416. 1927. Beitrage zur Kenntnis der Peridineen. II. resp. VII. Studien an Siisswasser-Ceratien. Ibid., 58: 344-440. Ernst, A. 1902. Siphoneen-Studien. 1. Dichotomosiphon tuberosus (A. Br.) Ernst, eine neue oogame Siisswasser-Siphonee. Beih. Bot. Centralbl., 138: 115-148; Pls. 6-10. 1904. Siphoneen-Studien. III. Zur Morphologie und Physiologie der Fortpflanzungszellen der Gattung Vaucheria DC. Ibid., 16: 367-382; Pl. 20. 1908. Beitrage zur Morphologie und Physiologie von Pithophora. Ann, Jard. Bot. Buitenzorg, 22: 18-55; Pls. 1-4. EsMarcH, FERDINAND. 1914. Untersuchungen iiber die Verbreitung der Cyano- phyceen auf und in verschiedenen Boden. Hedwigia, 55: 224-273. Fartow, W. G. 1877. Remarks on some algae found in the water supplies of the city of Boston. Bull. Bussey Inst., 2: 75-80. 1883. Relations of certain forms of algae to disagreeable tastes and odors. Science, 2: 333-334. Fassett, N. C. 1930. The plants of some northeastern Wisconsin lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 25: 157-168. Fircu, C. P., BisHor, Lucie M., et al. 1934. “Water bloom” as a cause of poisoning in domestic animals. Cornell Veterinarian, 24: 31-40. Fyerpincstap, E. 1945. Planktonstudien. I. Zur Ausbreitung der Microcystis aeruginosa Kiitz. emend. W. L., Microcystis flos-aquae (Wittr.) Kirchner emend. W.-L. und Microcystis viridis (A. Br.) Lemmermann. II. Das phyto- plankton im Vejle So im Sommer 1943 nebst einigen systematischen und biologischen Bemerkungen. Dansk. Bot. Ark., 12(No. 1): 1-21. FLAHAuLt, Cu. 1887. Note sur les Nostocacées hétérocystées de la flore Belge. Bull. Soc. Roy. Bot. Belgique, 26( Pt. II): 171-179. FLANicon, THomas H. 1943. Limnological observations on three lakes in eastern Vilas County, Wisconsin. Trans. Wis. Acad. Sci., Arts and Letters, 34: 167-175. Func, Eva M. 1939. One hundred algae of West Virginia. Castanea, 4: 5}, Fuint, L. H. 1947. Studies of freshwater red algae. Amer. Jour. Bot., 34(No. 3): 125-131; Figs. 1-31. 1948. Ibid., 85(No. 7): 428-433; Figs. 1-40. FLotow, J. von. 1844. Beobachtungen iiber Haematococcus pluviatilis. Nova Acta Acad. Caes. Leop.-Carol., 20: 413-606; Pls. 24-26. Focc, G. E. 1942. Studies on nitrogen fixation by blue-green algae. I. Nitrogen fixation by Anabaena cylindricum Lemm. Jour. Exper. Biol., 19: 78-87. Forti, A. 1907. Sylloge Myxophycearum. In G. B. DeToni, Sylloge algarum. V. Padua. Franze&, R. H. 1892. Beitriige zur Morphologie des Scenedesmus. Termés- ztrajzi Fiizetek kiadja a Magyar Nemzeti Muzeum, 15: 144-165. 1892a. Zur Systematik einiger Chlamydomonaden. Ibid., 15: 273-286. 1893. Ueber einige Algenformen. Oesterr. Bot. Zeit., 43: 202-205, 247-252, 282-286, 346-350, 381-386. FREEMAN, E. M. 1899. Observations on Chlorochytrium. Minn. Bot. Studies, 2(No. 16): 195-204. Fremy, P. 1922. Algues de l'Afrique centrale équatoriale. Bull. Soc. Bot. Linn. Normandie, 5: 25-26. 1924. Contribution a la flore algologique de l'Afrique équatoriale francaise. Rev. Algol., 1: 28-49. 1927. Les Scytonémacées de la France. In Flore algologique de France, Cyanophycées. Fasc. 1. Paris and Saint-L6. (Ibid. 1925. Rev. Algol., 2: 258-279. 1926. Ibid., 3: 55-98.) 1927a. Species des Stigonemacées de Normandie: Fischerella, Stigonema, Capsosira, Nostochopsis. Bull. Soc. Linn. Bot. Normandie, 9: 41-44. 1930. [ 624 ] Les Myxophycées de l’Afrique équatoriale frangaise. 507 pp.; Figs. 1-362. Thesis. Caen. 1930a. Algues provenant des récoltes de M. Henri Gadeau de Kerville dans le canton de Bagnéres-de-Luchon (Haut-Garonne). Bull. Soc. Amis Sci. Nat. Rouen, 1928-1929: 159-227; Figs. 1-139. 1936. Une nouvelle Cyanophycée précipitant de Yoxyde de fer. Microcoleus ferrugineus Frémy n. sp. Acta Inst. Bot. Univ. Zagreb., 11: 58-62; Figs. 1-7. 1936a. Les Lyngbyées de la Normandie. Soc. d’Archeol. et d’Hist. Nat. Dept. de la Manche, 47: 116-188; Figs. 1-18. 1938. Algues d’eau douce & subaériennes des anciennes antilles danoises. D’aprés les récoltes de M. le Dr. Boergesen. Mém. Soc. Nation. Sci. Nat. et Math. Cherbourg, 43: 37-62; Figs. 1-6. FrEsENtvs, G. 1851. Ueber Sphaeroplea annulina. Bot. Zeit., 9: 241-248; Pl. 6. 1858. Beitrage zur Kenntniss mikroskopischer Organismen. Abh. Senck. Nat. Ges., Frankfurt A.M., 2: 211-242. Frizs, E. M. 1825. Systema orbis vegetabilis. Plantae homonemeae. 374 pp: Fritscu, F. E. 1902. Algological notes. I. Observations on species of Aphano- chaete. II. The germination of zoospores in Oedogonium. Ann. Bot., 16: 403-417; Figs. 1-7, 23. 1902a. Algological notes.—III. Preliminary report on the phytoplankton of the Thames. Ibid., 16: 576-584. 1903. Further observations on the phytoplankton of the River Thames. Ibid., 17: 631-647. 1905. Algological notes. VI. The plankton of some English rivers. Ibid., 19: 163-167. 1907. A general consideration of the subaérial and fresh-water algal flora of Ceylon, Part I. Subaérial algae and algae of the inland fresh- waters. Proc. Roy. Soc. London (B), 79: 197-254 .1907a. The subaérial and freshwater algal flora of the tropics. Ann. Bot., 21: 235-275. 1914. Notes on British flagellates. I-IV. New Phytol., 13: 341-351. 1916. The algal ancestry of the higher plants. Ibid., 15: 233-250; Figs. 1,2. 1918. A con- tribution to our knowledge of the fresh-water algae of Africa. Ann. S. African Mus., 9: 483-611. 1929. The encrusting algal communities of certain fast-flowing streams. New Phytol., 28: 165-196. 1929a. Evolutionary se- quence and affinities among protophyta. Biol. Rev. and Biol. Proc. Cambridge Philos. Soc., 4: 103-151; Figs. 1-7. 1929b. The genus Sphaeroplea. Ann. Bot., 43: 1-26; Figs. 1-8. 1931. Some aspects of the ecology of fresh-water algae. Jour. Ecol., 19: 233-272. 1935.+ The structure and reproduction of the algae. I. 791 pp.; Figs. 1-245. New York. 1942. The interrelations and classification of the Myxophyceae (Cyanophyceae). New Phytol., 41: 134-148; Figs. 1-5. 1945.+ The structure and reproduction of the algae. II. 939 pp.; Figs. 1-335. New York. Fritscu, F. E., and Der, P. K. 1938. Nitrogen fixation by blue-green algae. Nature, 142: 878. Fritscu, F. E., and Jonn, R. P. 1942. An ecological and taxonomic study of the algae of British soils. II. Consideration of the species observed. Ann. Bot., 6(n.s.): 371-395; Figs. 1-8. Fritscu, F, E., and Rich, FLoreNce. 1913. Studies on the occurrence and re- production of British freshwater algae in nature. 3. A four year’s observation of a freshwater pond. Ann. Biol. Lacustre, 6: 33-115. 1930. Contributions to our knowledge of the freshwater algae of Africa. 7. Freshwater algae (exclusive of diatoms) from Griqualand West. Trans. ny Soc. S. Africa, 18(1929): 1-92; Figs. 1-32. 1937. Contributions to our knowledge of the freshwater algae of Africa. 12. Algae from the Belfast Pan, Transvaal. Ibid , 25( Pt. IL): 153-228; Figs. 1-31. Fritscn, F. E., and StepHens, Epiru L. 1921. Contributions to our knowledge of the freshwater algae of Africa. 2. Fresh-water algae (exclusive of diatoms), [ 625 ] mainly from the Transkei Territories, Cape Colony. Trans. Roy. Soc. S. Africa, 9(Pt. 1): 1-72; Figs. 1-29. Frirscu, F. E., and Taxepa, H. 1916. On a species of Chlamydomonas (C. sphagnicola F. E. Fritsch and Takeda—Isococcus sphagnicolus, F. E. Fritsch). Ann Bot., 30: 373-377; Figs. 1-12. Gamwukxov, N. 1903. Ueber die Kulturen und die Uronema-Zustand der Ulothrix flaccida. Ber. d. Deutsch. Bot. Ges., 21: 522-524. Garsint, A. 1899. Intorno al plankton dei laghi di Mantova. Atti e Mem. Accad. Verona, 74(Ser. 3) Fasc. 3: 255-314. 1901. Intorno plankton del Lago Maggiore. Ibid., 76(Ser. 3), Fasc. 2: 67-80. Garp, M. 1920. Division chez Euglena limosa Gard. Comp. Rend. Acad. Sci. Paris, 170: 291-292. 1922. Recherches sur une nouvelle espéce d’Euglene (Euglena limosa nov. spec.). Bull. Soc, Bot. France, 69: 306-313. Garpner, N. L. 1927. New Myxophyceae from Porto Rico. Mem. N. Y. Bot. Gard., 7: 1-144. Gates, F. C. 1912.* The vegetation of the beach area in northeastern Illinois and southeastern Wisconsin. Bull. Ill. State Lab. Nat. Hist., 9: 255-372. Gay, F. 1888. Sur les Ulothrix aériens. Bull. Soc. Bot. France, 35: 65-75. 1891. Recherches sur le développement et la classification de quelques algues vertes. 116 pp.; Pls. 1-15. Paris. 189la. Le genre Rhizoclonium. Jour. Bot. 5: 538-58. GeirLer, L. 1921. Versuch einer Lésung des Heterocysten-Problems. Sitz. K. K. Akad. Wiss. Wien, Math.-Nat. KI., 130: 223-245. 192la. Kleine Mitteil- ungen uber Blaualgen. Oesterr. Bot. Zeit., 70: 158-167; Figs. 1-7. 1923. Studien iiber das Hamatochrom und die Chromatophoren von Trentepohlia. Ibid., 72: 76-83; Figs. 1-5. 1923a. Der Zellbau von Glaucocystis Nostochin- earum und Gloeochaete Wittrockiana und die Chromatophoren-Symbios- theorie von Mereschkowsky. Arch. f. Protist., 47: 1-24; Pl. 1. 1924. Die Entwicklungsgeschichte von Sorastrum spinulosmum und die Phylogenie der Protococcales. Ibid., 47: 440-447; Pl. 22. 1925. Beitraége zur Kenntnis der Flora ostholsteinischer Seen. Ibid., 52: 603-611. 1925a. Cyanophyceae. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 12: 1-450; Figs. 1-560. 1925b. Ueber neue oder wenig bekannte interessante Cyanophyceen aus der Gruppe der Chamaesiphoneae. Arch. f. Protist., 51: 321-360; Pls. 12, 13. 1928. Neue Blaualgen aus Lunz. Ibid., 60: 440-448. 1928a. Zwei neue Dinophyceenarten. Ibid., 61: 1-8. 1928b. Neue Gattungen und Arten von Dinophyceen, Heterokonten und Chrysophyceen. Ibid., 63: 67-83; Pl. 7. 1930. Ueber die Kernteilung von Spirogyra. Ibid., 71: 79-100. 1930-1931.+ Cyanophyceae. In L. Rabenhorst, Kryptogamen- Flora von Deutschland, Oesterreich und der Schweiz. 14, Lf. 1( 1930): 1-288; Lf. 2(1931): 289-464; Figs. 1-131. Leipzig. 193la. Untersuchungen iiber das sexuelle Verhalten von Tetraspora lubrica. Biol. Centralbl., 51: 173-187; Figs. 1-5. Getus, S. S., and Crarxe, G. L. 1935. Organic matter in dissolved and in colloidal form as food for Daphnia magna. Physiol. Zool., 8: 127-137. GeMEInHarpT, K. 1938-1939.t Oedogoniales. In L. Rabenhorst, Kryptogamen- Flora von Deutschland, Oesterreich und der Schweiz. 12, Abt. 4: 1-453; Figs. 1-539. Leipzig. Gervorr, J. 1940. Beitrage zur Kenntnis der Variabilitét und Systematik der Gattung Chlamydomonas. Arch. f. Protist., 94: 311-502; Figs. 148. Gernecx, R. 1907. Zur Kenntnis niederen Chlorophyceen. Beih. Bot Centralbl , 21( Abt. 2): 221-290; Pls. 11, 12. [ 626 ] GicktHorn, J. 1921. Ueber den Blauglanz zweier neuer Oscillatorien. Oesterr. Bot. Zeit., 70: 1-11. Gmes1, N. 1930. Die Geburt von Trachelomonas volvocina Ehrb. Arch. f. Protist., 72: 190-197; Pl. 14. Ge.in, C. G. 1826. Flora Badensis Alsatica. IV: 643-647. Carlsruhe. (Not seen. ) Gost, C. 1879. Kurzer Bericht iieber die im Sommer 1878 ausgefiihrte algolo- gische Excursion (rossice). St. Petersb. Ges. d. Naturf., 10: 93-97. 1886- 1887. Peroniella Hyalothecae, eine neue Siisswasseralge. Script. Bot. Hort. Petropol., 1(Fasc. 2): 233-250; 1 pl. Gorz, H. 1897. Zur Systematik der Gattung Vaucheria DC. speciell der Arten der Umgebung Basels. Flora, 83: 88-134; Figs. 1-55. Goynics, Mary. 1934. The cell morphology and division of Euglena deses Ehrbg. Trans. Amer. Microsc. Soc., 53: 999-310; Pls. 21-23. 1939. Some observations on Euglena sanguinea Ehrbg. Ibid., 58: 241-248; 1 pl. Gotenkin, M. 1899. Algologische Mitteilungen. Ueber die Befruchtung bei Sphaeroplea annulina und iiber die Struktur bei einigen grunen Algen. Bull. Soc. Imp. Nat. Moscou, 13: 343-361. Gomont, M. 1885. Sur deux algues nouvelles des environs de Paris. Bull. Soc. Bot. France, 32: 208-212. 1890. Essai de classification des Nostocacées homocystées. Jour. Bot., 4: 349-357. 1892. Monographie des Oscillariées (Nostocacées homocystées). Part 1. Ann. Sci. Nat. Bot., 15(Sér. 7): 263— 368; Pls. 6-14. 1892a.t+ Monographie des Oscillariées. Part 2. Ibid., 16(Sér 7): 91-264; Pls. 1-7. 1893.+ Monographie des Oscillariées (Nostocacées homocystées). Paris. 1895. Note sur le Scytonema ambiguum Kiitz. Jour. Bot., 9: 49-53. 1895a. Note sur un Calothrix sporifere (Calothrix stagnalis sp. n.). Ibid., 9: 197-202. GoroscHankn, J. 1891. Beitriige zur Kenntnis der Morphologie und Systematik der Chlamydomonaden. I. Chlamydomonas Braunii. Bull. Soc. Imp. Nat. Moscou, 1890 (No. 3): 498-520; Pls. 14,15. 1891. Beitrage zur Kenntniss der Morphologie und Systematik der Chlamydomonaden. I. Chlamydomonas - Reinhardii (Dangeard) und seine Verwandten. Pls. 1-8. Moskau. Grecer, J. 1915. Beitrag zur Kenntnis der Entwicklung und Fortpflanzung der Gattung Microthamnion Naeg. Hedwigia, 56: 374-380. Grevitte, k. K. 1824. Flora Edinensis. Edinburgh. 1830, Algae britannicae. Edinburgh. Grirrirus, B. M. 1912. The algae of Stanklin Pool, Worcestershire; an account of their distribution and periodicity. Proc. Birmingham Nat. Hist. and Phil. Soc., 12: 1-23. 1915. On Glaucocystis Nostochinearum, Itzigsohn. Ann. Bot., 29: 423-432; Pl. 19. Groves, J., and Buttock-WessTER, G. R. 1920-1924.+ The British Charophyta. I, 1920; II, 1924. Ray Society, London. Grunow, A. 1858. Die Desmidiaceen und Pediastreen einiger Oesterreichischen Moore, nebst einigen Bemerkungen iiber beide Familien im Allgemeinen. Ver. K. K. Zool.-Bot. Ges. Wien, 8: 489-502. 1867. Algen. Leipzig. Ginruer, F. 1928. Ueber der Bau und die Lebensweise der Euglenen, besonders der Arten E. terricola, geniculata, proxima, sanguinea und lucens nov. spec. Arch. f. Protist., 60: 511-590; Pls. 13-15; Figs: 1-5. Guciie_metti, G. 1910. Contribuzioni alla flora algologica Italiana. I. Proto- coccaceae raccolte nel Padovano. Nuova Notarisia, 21: 28-39. Gusrarson, A. H. 1942.* Notes on the algal flora of Michigan. Pap. Mich. Acad. Sci., Arts and Letters, 27(1941): 27-36. 1942a. Notes on some fresh- water algae from New England. Rhodora, 44: 64-69. [ 627 ] Gutwinski, R. 1890. Zur Wahrung der Prioritiét. Vor laiifige Mittheilungen iiber einige neue Algen-Species und Varietaéten aus der Umgebung von Lemberg. Bot. Centralbl., 43: 65-73. 1893. Glony stawé6w na Zbruczu. Akad. Umiej. w Krakowie Spraw. Komisyi Fizyogr., 29: 23-28. 1894. Flora glonow okolic Tarnapola. Ibid., 30: 45-173. 1894a. Glony stawow na Zbruczu (Ueber die in den Teichen des Zbrucz-Flusses gesammelten Algen). Ibid., 29: 23-38. 1896. De nonnulis algis novis vel minus cognitis. Akad. Umiej. w Krakowie, Rozpr. Wydz. Mat.-Przyr. 83: 82-63. 1897. Materyaly do flory Glonow Galicyi. Res ad floram algarum Galiciae congestae. Pars IV. A. Algae a Prof. Arsenio Dorozynski in Mizun ad Dolina anno 1896 collectae. B. Algae a Prof. Francisco Tondera in Knihynin ad Stanislowé6w anno 1894 collectae. Nuova Notarisia, 8: 125-136. 1900. Additamenta ad floram algarum Indiae Batavorum cognoscendam. Algae a cl. Dre. M. Raci- borski in montibus vulcanis: Kraktau et Slamat anno 1897 collectae. Diss. Mat.-Physic. Acad. Litter. Cracoviens, 89: 287-307; Anz. Akad. Wiss. Krakau, 1900. 400-402. 1902. De algis a Dre. M. Raciborski anno 1899. in insula Java collectis. Bull. Inter. Acad. Sci. Cracovie, Cl. Sci. Math. et Nat., 1902: 575-617; Pls. 36-40. 1909. Flora algarum montium Tatrensium. Ibid., 4: 415-560. 1913. Ueber die Algenflora und das Plankton des Tatra-Sees “Morskie Oko’. Kosmos, 1923: 1426-1437 (reprint). Haase, G. 1910. Studien iiber Euglena sanguinea. Arch. f. Protist., 20: 47-59; Pls. 4-6. Hare, Frank E. 1930. Control of microscopic organisms in public water supplies, with particular reference to New York City. New Eng. Water Works Assoc., 44: 361-385. Hatxas, E. D. 1905. Nye Arter af Oedogonium fra Danmark. Bot. Tids., 26: 3897-410. Hamet, G. 1925. Floridées de France. III. Rev. Algol., 2: 839-67, 280-309. Hami.ton, J. M. 1948. Sexual reproduction in the genus Basicladia (Thallo- phyta) Chlorophyceae. Trans. Amer. Microsc. Soc. 67: 201-205; Figs. 1-9. Hanscirc, A. 1883. Beitrage zur Kenntniss der Flora von Bohmen. I, II. Sitz. d. Konig]. Bohm. Ges. d. Wiss. Math.-Nat. Kl. Prag, 1882: 280-289. 1883a. Neue Beitrage zur Algenkunde Bohmens. Ibid., 1883: 203-211; Neue Beitrage zur Kenntniss bohmischer Algen. Ibid., 1883: 263-273; Neue Beitrage zur Kenntniss der béhmischen Algenflora. Ibid., 1883: 360-371. 1885. Anhang zu meiner Abhandlung “Ueber Polymorphismus der Algen.” Bot. Centralbl., 23: 229-233. 1885a. Ueber den Polymorphismus der Algen. Ibid., 23: 385-406. 1886.+ Prodromus der Algenflora von Béhmen. Erster Theil enthaltend die Rhodophyceen, Phaeophyceen und einen Theil der Chlorophyceen. Heft 1. Archiv f. Natur. Landes von Béhm., 5( Bot. Abth.): 3-96; Figs. 1-126. 1887. Ueber Trentepohlia (Chroolepus) artige Moosvor- keimbildungen. Flora, 70: 81-85. 1887a. Algarum aquae dulcis species novae. Oesterr. Bot. Zeit., 37: 121-122. 1888.+ Prodromus der Algenflora von Bohmen. Erster Theil enthaltend die Rhodophyceen, Phaeophyceen und Chlorophyceen. Heft 2. Archiv f. Natur. Landes von Béhm., 6(No. 5): 3-290. 1888a. Ueber die Siisswasser-gattungen Trochiscia Ktz. (Astericium Corda, Polyedrium Nag., Cerasterias Reinsch). Hedwigia, 27: 126-132. 1888b. Synopsis generum subgenerumque Myxophycearum (Cyanophycea- rum) hucusque cognitorum, cum descriptione generis nov. “Dactylococcop- sis.” Notarisia, 3: 584-590. 1888c. Beitrag zur Kenntniss der Algengattungen Entocladia Reinke, etc. Flora, 71: 499-507; Pl. 12. 1888d. De Spirogyra insigni (Hass.) Ktz. nov. var. fallaci, Zygnemate chlabeospermo nov. sp. et [ 628 ] Z. rhynconemate nov. sp., aijecto conspectu subgenerum. sectionum, sub- sectionumque generis Spirogyrae Link et Zygnematis (Ag.) DeBy. Hedwigia, 27: 253-258; Pl. 10. 1888e. Algae novae aquae dulcis. Notarisia, 3(No. 9): 398-400. 1888f. Ueber die Gattungen Herpostiron Nag. und Aphanochaete Berth. non A. Br., etc. Flora, 71: 211-223. 1889. Nachtrage zu den in Hedwigia 1888, No. 5 und 6, No. 9 und 10 verdffentlichten Abhandlungen. Hedwigia, 28: 17-19. 1889a. Resultate der vom Verfasser im J. 1888 ausge- fihrten Durchforschung, der Siisswasseralgen und der saprophytischen Bac- terien Bohmens. Sitz. d. Konig]. Bohm. Ges. d. Wiss. Math.-Nat. Kl. Prag, 1889: 121-164. 1890. Uber neue Siisswasser- und Meeres-Algen und Bac- terien, mit Bemerkungen zur Systematik dieser Phycophyten und iiber den Einfluss des Lichtes auf die Ortsbewegungen des Bacillus Pfefferi, nob. Ibid., 1890: 1-34. 1890a. Physiologische und algologische Mittheilungen. Ibid., 1890: 83-140. 1891. Algologische und bacteriologische Mittheilungen. Ibid., 1891: 300-365. 1892[1893]. Prodromus der Algenflora von Bohmen. Zweitet Theil welcher die blaugriinen Algen (Myxophyceen, Cyanophyceen), nebst Nachtragen zum ersten Theile und einer systematischen Bearbeitung der in Béhmen verbreiteten saprophytischen Bacterien und Eugleenen enthalt. Archiv f. Natur. Landes von Bohm., 8(Bot. Abth.): 1-268; Figs. 1-67. 1892a. Beitrage zur Kenntnis der Siisswasser-Algen und Bacterien-Flora von Tirol und Béhmen. Sitz. d. Konig]. Béhm. Ges. d. Wiss. Prag, 1892: 105-156. 1893. Mein letztes Wort iiber Chaetosphaeridium Pringsheimii Kleb. und Aphanochaete globose (Nordst.) Wolle. Bot. Centralbl., 56: 321-326. 1905. Grundziige der Algenflora von Niederosterreich. Beih. Bot. Centralbl., 18: 417-522. Harior, P. 1889-1890. Notes sur le genre Trentepohlia Martius. Jour. Bot., 3(1889): 345-350, 366-375, 378-388, 393-405. Ibid., 4(1890): 50-53, 85-92, 178-189, 192-197; Figs. 1-24. 1891. Le genre Polycoccus Kuetzing. Ibid., 5: 29-32. 1895. Algues du Golfe de California. Ibid., 9: 167-170. Harper, R. A. 1908.* Organization of certain coenobic plants. Bull. Univ. Wis. No. 207(Sci. Ser., 3): 279-334; Pls. 1-4. 1916. On the nature of types in Pediastrum. Mem. N. Y. Bot. Gard., 6: 91-104; Figs. 1, 2. 1918. Organisation, reproduction, and inheritance in Pediastrum. Proc. Amer. Philos. Soc., 57: 375-439; Pls. 5-6. 1918a. The evolution of cell types and contact and pressure responses in Pediastrum. Mem. Torr. Bot. Club, 17: 210-240; Figs. 1-27. Harvey, F. L. 1888. The freshwater algae of Maine. I. Bull. Torr. Bot. Club, 15: 155-161. 1889. Ibid. Il. Ibid., 16: 181-188. 1892. Ibid. II. Ibid., 19: 118-125. Harvey, H. W. 1926. Nitrates in the sea. Jour. Mar. Biol. Assoc., 14: 71—88. Harvey, W. H. 1833. Algae Gloiocladeae. In Hooker’s British Flora, 5: 385- 400. London. 1855-1859. In J. D. Hooker, The botany of the antarctic voyage. Part III. Flora Tasmania. 1858. Nereis Boreali-Americana. Ill. Chlorospermeae. Smiths. Contrib. Knowledge, 10( No. 2): 1-140; Pls. 37-50. Hassatx, A. H. 1842. Observations on the genera Zygnema, Tyndaridea and Mougeotia, with descriptions of new species. Ann. and Mag. Nat. Hist., 10(Ser. 1): 34-47. 1843. Descriptions of British freshwater Confervae, mostly new, with observations on some of the genera. Ibid., 11(Ser. 1): 428-437. 1843a. Observations on some points in the anatomy and physiology of the freshwater algae. Ibid., 12(Ser. 1): 20-30; 1 pl. 1843b. Observations on the genus Mougeotia, on two new genera of fresh water algae, and on Tyndaridea, with descriptions of species. Ibid., 12(Ser. 1): 180-188; 1 pl. 1843c. Observations on the growth, reproduction, and species of the branched fresh-water Confervae. Ibid., 11(Ser. 1): 359-364. 1845. A history [ 629 ] of fresh-water algae. 462 pp.; Pls. 1-103. London. 1852. A history of the freshwater algae, including descriptions of Desmidiaceae and Diatomaceae. 2 vols. 462 pp.; Pls. I-CIII. London. Hasstow, O. J. 1939. Einige Characeenbestimmungen. Bot. Notiser, 1939: 295-301, 817-818. Hauck, F. 1885. Die Meeresalgen Deutschlands und Oesterreichs. In Raben- horst’s Kryptogamenflora. II. Leipzig. Haypen, Apa. 1910. The algal flora of the Missouri Botanical Garden. 21st Ann. Rep. Missouri Bot. Gard., 1910: 25-48; Pls. 1-5. Hazen, Tracy E. 1899. The life history of Sphaerella lacustris (Haematococcus pluvialis). Mem. Torr. Bot. Club, 6: 211-224; Pls. 86-87. 1902. The Ulo- thricaceae and Chaetophoraceae of the United States. Ibid., 11: 135-250; Pls. 20-42. HeeErInG, W. 1906. Die Siisswasseralgen Schleswig-Holstein, etc. Jahrb. Ham- burg. Wiss. Anstal., 23(1905): 61-150. 1914.+ Ulotrichales, Microsporales, Oedogoniales. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 6. Chlorophyceae 3: 1-250; Figs. 1-384. Jena. 1921.+ Siphonocladiales, Siphonales. Ibid. Heft 7. Chlorophyceae 4: 1-103; Figs. 1-94. Jena. HeeErinc, W., and Homrexp, H. 1905. Die Algen des Eppendorfer Moores bei Hamburg. Ver. Natur. Ver. in Hamburg, 12(1904): 77-97. HernricuEer, E, 1883. Zur Kenntniss der Algengattung Sphaeroplea. Ber. d. Deutsch. Bot. Ges., 1: 483-450; Pl. 12. Henrrey, A. 1859. On Chlorosphaera, a new genus of uni-cellular fresh-water algae. Trans. Microsc. Soc. London, 7(n.s.): 25-29; Pl. 3. Henrici, A. T. 1938. Studies of freshwater bacteria. IV. Seasonal fluctuations of lake bacteria in relation to plankton production. Jour. Bact., 35: 129-139. 1939. The distribution of bacteria in lakes. In Problems of lake biology. Amer. Assoc. Adv. Sci., Publ. No. 10: 39-64. Henrici, A. T., and McCoy, ExizasetH. 1938. The distribution of hetero- trophic bacteria in the bottom deposits of some lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 31: 323-361. HERMANN, J. 1863. Ueber die bei Neudamm aufgefundenen Arten der Genus Characium. Leipzig. Hirronymus, G. 1887. Ueber einige Algen des Riesengebirges. Jahr. Schles. Ges. Vater. Kul., 1887: 293-297. 1892. Ueber Dicranochaete reniformis Hieron., eine neue Protococcacea des Siisswassers. Beitr. Biol. Pflanzen., 5: 351-372; Pls. 11, 12. 1892a. Beitraége zur Morphologie und Biologie der Algen. I. Glaucocystis Nostochinearum Itzigsohn. Ibid., 5: 461-495. 1895. Bemerkungen iiber einige Arten der Gattung Stigonema Ag. Hedwigia, 34: 154-172. HicrnsotHaM, Nor. 1942. Cephalomonas, a new genus of the Volvocales. Bull. Torr. Bot. Club, 69: 661-668; Figs. 1-43. Hirn, Kart E. 1895. Verzeichnis finlandischer Oedogoniacéen. Acta Soc. Fauna et Flora Fenn., 11(No. 6): 1-24. 1895a. Die Finnlandischen Zygne- maceen. Ibid., 11(No. 10): 1-15. 1900.+ Monographie und iconographie der Oedogoniaceen. Acta Soc. Sci. Fenn., 27: 1-395; Pls. 1-64; Figs. 1-27. 1900a. Finnlindische Vaucheriaceen. Medd. Soc. Fauna et Flora Fenn., 26(1900): 1-6 (reprint). Hopcetts, W. J. 1918. Uronema elongatum, a new fresh water member of the Ulotrichaceae. New Phytol., 17: 159-166; Figs. 1-11. 1921. A study of some of the factors controlling the periodicity of fresh-water algae in nature. Ibid., 20: 150-164, 195-227. 1922. Ibid., 21: 15-38; Figs. 1-11. [ 630 ] HorrMan, W. E., and TILDEN, JOSEPHINE. 1930. Basicladia, a new genus of Cladophoraceae. Bot. Gaz., 89: 374-384; Figs. 1-22. Horan, R. M., and Reep, E. 1918.* Notes on the phytoplankton and other algae of Douglas Lake and vicinity. Ann. Rep. Mich. Acad. Sci., 20: 153-154. Hooker, J. D. 1855-1859. The botany of the antarctic voyage. Part III. Flora Tasmaniae. Hooxer, W. J. 1833. The English flora. 5. Part 1. 432 pp. London. Hoppaucn, KATHERINE. 1930.t A taxonomic study of species of the genus Vaucheria collected in California. Amer. Jour. Bot., 17: 8329-347; Pls. 24-27. Huser, J. 1892. Contributions 4 la connaissance des Chaetophorées épiphytes et endophytes et de leurs affinités. Ann. Sci. Nat. Bot., 16(Sér. 7): 265- 359; Pls. 8-18. 1894. Sur ! Aphanochaete repens A. Braun et sa reproduction sexuée. Bull. Soc. Bot. France, 41(Sér. 3): XCIV—CII. Hvuser-PestaLozzi, G. 1919. Morphologie und Entwicklungsgeschichte von Gloeotaenium Loitelsbergerianum Hansgirg. Zeit. f. Bot., 11: 401-472. 1924. Notiz iiber Gloeotaenium Loitelsbergerianum Hansgirg. Ibid., 16: 624-626. 1925. Zur Morphologie und Entwicklungsgeschichte von Asterothrix (Cera- sterias) raphidioides (Reinsch) Printz. Hedwigia, 65: 169-178; Figs. 1-5. 1929. Das Phytoplankton naturlicher und kiinstlicher Seebecken Siidafrikas. Ver. Inter. Vereining. f. Theor. u. Angew. Limnol., 4: 343-390. 1930. Algen aus dem Knysnawalde in Siidafrika. Zeit. f. Bot., 23: 443-480. 1938.+ Das Phytoplanktons des Siisswassers. Systematik und Biologie. 1 Teil. Stuttgart. 342 pp.; Pls. 3-66. 1941. Ibid. 2 Teil. Stuttgart. Huser-Pestatozzi, G., and Naumann, E. 1929. Phormidium mucicola Nau- mann et Huber, ein Epibiont in der Gallerte pflanzlicher und tierischer Planktonorganismen. Ber. d. Deutsch. Bot. Ges., 47: 67-76. Huesner, E. 1886. Euglenaceen-Flora von Stralsund. Progr. d. Realgymnasiums zu Stralsund. Ostern. Hurr, N. L. 1923. Observations on the relation of algae to certain animals of Vadnais Lake. Univ. Minn. Biol. Sci., 4: 185-197. Hucues, E. O. 1948. New fresh-water Chlorophyceae from Nova Scotia. Amer. Jour. Bot., 35(No. 7): 424427; Figs. 1-6. Hurrretpt-Kaas, H. 1900. Die limnetischen Peridineen in norwegischen Bin- nenseen. Vidensk. Skrifter, Mat.-Nat. KI. Christiania, 1900(No. 2): 1-7. Hurcuinson, G. Evetyn. 1944, Limnological studies in Connecticut. VII. A critical examination of the supposed relationship between phytoplankton periodicity and chemical changes in lake waters. Ecology, 25: 3-26. Hyanper, C. J. 1928. The algae of Connecticut. Bull. Conn. Geol. and Nat. Hist. Surv., 42: 1-245; Pls. 1-28. Hy, T. C. 1913-1914. Les Characées de France. Bull. Soc. Bot. France, 60(1913. Mém. 26): 1-47. Note additionelle. Ibid., 61(1914): 235-241. Imuor, O. E. 1887. Studien iiber die Fauna hochalpiner Seen, insbesondere des Cantons Graubiinden. Jahrb. d. Naturf. Ges. Graubiindens, 30: 45-164. 1890. Das Flagellatengenus Dinobryon. Zool. Anz., 13: 483-488. IsRAELSSON, GuNNAR. 1938. Ueber die Siisswasserphaeophyceen Schwedens. Bot. Notiser, 1938, 113-128. Irzicsonn, H. 1850. Charologisches. Bot. Zeit., 8: 337-340. 1855. Skizzen zu einer Lebensgeschichte des Hapalosiphon Braunii. Acta Acad. Caes. Leop.- Carol., 25: 249-298. Iwanorr, L. A. 1898. Zur Entwicklungsgeschichte von Botrydium granulatum Woronin et Rostaf. Trav. Soc. Imp. Nat. St. Pétersb. Comp. Rend., 29( No. 4): 155-156. (Not seen.) 1898a. Zur Entwicklungsgeschichte von Botrydium [ 631 ] granulatum Woronin et Rostaf. Arb. d. Kais. St. Petersb. Ges. d. Naturf., 29: 1-10. 1900. Ueber neue Arten von Algen und Flagellaten (Stigeoclonium, Vaucheria, Spirogyra, Gonyostomum), welche an der biologischen Station zu Bologoje gefunden worden sind. Bull. Soc. Imp. Nat. Moscou, 1899(No. 4): 423-449, 1900a. Beitrag zur Kenntnis der Morphologie und Systematik der Chrysomonadinen. Bull. Acad. Imp. Sci. St. Pétersb. 11: 247-262; 1 pl.; Figs. A, B. IyeNcAR, M. O. P. 1923. Notes on some attached forms of Zygnemaceae. Jour. Indian Bot. Soc., 2: 1-9. 1925. Note on two species of Botrydium from India. Ibid., 4: 193-201. 1925a. Hydrodictyon indicum, a new species from Madras. Ibid., 4: 315-317. 1933. Contributions to our knowledge of the colonial Volvocales of South India. Jour. Linn. Soc. Bot., 49: 323-373. Ivencar, M. O. P., and Ivencar, M. O. T. 1932 On a Characium growing on Anopheles larvae. New Phytol., 31: 66-69. Jaun, T. L. 1946. The euglenoid flagellates. Quart. Rev. Biol., 21: 246-274; Figs. 1-6. Janet, C. 1912. Le Volvox. Limoges. 1918. Botrydium granulatum. Limoges. 1922. Le Volvox. Deuziéme mémoire. Paris. 1923. Le Volvox. Troisieme mémoire. 179 pp.; Pls. 5-21. Paris. Jao, C. C. 1934. New Oedogonia collected in China. Pap. Mich. Acad. Sci., Arts, and Letters, 19(1933): 83-92; Pls. 5-7. 1934a. Oedogonium in the vicinity of Woods Hole, Massachusetts. Rhodora, 36: 197-214; Pls. 286— 288. 1935. New Oedogonia collected in China. I. Pap. Mich. Acad. Sci., Arts, and Letters, 20(1934): 57-63; Pls. X, XI. 1935a. New Zygnemataceae from Woods Hole. Trans. Amer. Microsc. Soc., 54: 1-7; Pl. 1. 1936. Notes on Oedogonium and Bulbochaete in the vicinity of Woods Hole, Massa- chusetts. Rhodora, 38: 67-73; Pl. 407. 1936a. New Zygnemataceae collected in China. Amer. Jour. Bot., 23: 53-60. Jorcensen, E. 1911. De Ceratien. Eine kurze Monographie der Gattung Ceratium Schrank. Inter. Rev. d. Ges. Hydrobiol. u. Hydrogr., 4(Suppl.), Pt. 1: 1-124. Jounson, L. N. 1894.* Some new and rare desmids of the U.S. I. Bull. Torr. Bot. Club, 21: 285-291. 1895.* Ibid. I. Ibid., 22: 289-298. Jounson, L. P. 1944.+ Euglenae of Iowa. Trans. Amer. Microsc. Soc., 63: 97-135; Pls. 1-6. Jotxos, V. 1910. Dinoflagellatenstudien. Arch. f. Protist., 19: 178-206; Pls. 7-10. Josr, L. 1895. Beitriige zur Kenntniss der Coleochaeteen. Ber. d. Deutsch. Bot. Ges., 18: 483-452; Pl. 34. Jupay, C. 1914. The inland lakes of Wisconsin. The hydrography and mor- phometry of the lakes. Bull. Wis. Geol. and Nat. Hist. Surv., 27 (Sci. Ser. No. 9): 1-157. 1934.* The depth distribution of some aquatic plants. Ecology, 15: 325. 1942. The summer standing crop of plants and animals in four Wisconsin lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 34: 103-135; Figs. 1-4. Jupay, C., and Bircr, E. A. 1931. A second report on the phosphorus content of Wisconsin lake waters. Trans. Wis. Acad. Sci., Arts, and Letters, 26: 353-382. 1941. Hydrography and morphometry of some northeastern Wis- consin lakes. Ibid., 833: 21-72. Jupay, C., Bice, E. A., Kemmerer, G. I., and Rosinson, R. J. 1927. Phos- phorus content of lake waters of northeastern Wisconsin. Trans. Wis. Acad, Sci., Arts, and Letters, 23: 233-248. Jupay, C., Brrcr, E. A., and MELocHE, V. W. 1935. The carbon dioxide and hydrogen ion content of the lake waters of northeastern Wisconsin. Trans. [ 632 ] Wis. Acad. Sci., Arts, and Letters, 29: 1-82. 1938. Mineral content of the lake waters of northeastern Wisconsin. Ibid., 31: 223-276. Jupay, C., and ScHomer, H. A. 1935.* The utilization of solar radiation by algae at different depths in lakes. Biol. Bull., 69: 75-81. Jurcens, G. H. B. 1822. Algae aquaticae. Dec. XV. Just, L. 1822. Phyllosiphon Arisari. Bot. Zeit., 40: 1-8, 17-26, 33-47, 49-57; Jelly Jt Kammerer, G. 1938. Volvocalen und Protococcalen aus dem unteren Ama- zonasgebiet. Sitz. K. K. Akad. Wiss. Wien. Math.-Nat. K]., 147(Abt. 1): 183-228. Karsten, G. 1891. Untersuchungen ueber die Familie der Chroolepideen. Ann. Jard. Bot. Buitenzorg, 10: 1-66; Pls. 1-6. Kasanowsky, V., and Smienorr, S. 1913. Spirogyra borysthenica n. sp. Oest. Bot. Zeit., 63: 137-141. Kater, J. M. 1929. Morphology and division of Chlamydomonas with reference to the phylogeny of the flagellate neuro-motor system. Univ. Calif. Publ. Zool., 33: 125-168; Pls. 11-16; Figs. 1-7. Krerr, A. M. 1926. A preserving fluid for green plants. Science, 64(n.s.): 331-332. 1927. A new species of Aphanocapsa. Rhodora, 29: 39-41. Kersster, K. von. 1911. Untersuchungen iiber die Periodizitit des Phyto- planktons des Leopoldsteiner-Sees in Steiermark, in Verbindung mit einer eingehenderen limnologischen Erforschung dieses Seebeckens. Arch. f. Hy- drobiol. u. Planktonk., 6: 480-485. Kemmerer, G., Bovarp, J. F., and Boorman, W. R. 1924. Northwestern lakes of the United States. Bull. U. S. Bur. Fish., 39: 51-140. Kent, S. 1880-1882. (See Seville-Kent, W.) Krener, W. 1944. Notes on distribution and bio-ecology of Characeae in Ne- braska. Butler Univ. Studies Bot., 6: 131-148. Kinpte, E. M. 1915. Limestone solution on the bottom of Lake Ontario. Amer. Jour. Sci., 189: 651-656; Figs. 1-3. Kincuner, O. 1878. Algen. In F. Cohn, Kryptogamen-Flora von Schlesien Breslau. 1900. Schizophyceae. In A. Engler and K. Prantl, Die Natiirlichen Pflanzenfamilien. 1 Teil, Abt. la: 45-92. Leipzig. KissELEw, J. A. 1927. Zur Kenntnis der Algen des Aralsees. Bul. Bur. Appl Ichth., 5: 274-305. 1931. Zur Morphologie einiger neuer und seltener Vertreter des pflanzlichen Microplanktons. Arch. f. Protist., 73: 235-250. Kyettman, F. R. 1898. Zur Organographie und Systematik der Aegagropilen. Nova Acta Reg. Soc. Sc. Upsala, 17(Ser. 8): No. 7: 1-26. Kiepann, H. 1892. Chaetosphaeridium Pringsheimii, novum genus et nova species algarum chlorophycearum aquae dulcis. Pringsh. Jahrb. f. Wiss. Bot., 94: 268-282: Pl. 4. 1893. Zur Kritik einiger Algengattungen. Ibid. 25: 278-321; Pl. 14. 1895. Gasvacuolen, ein Bestandtheil der Zellen der wasser- bliithebildenden Phycochromaceen. Flora, 80: 241-282; Pl. 4. 1896. Ueber wasserbliithebildende Algen, insbesondere des Pléner Seengebiets, und iiber das Vorkommen von Gasvacuolen bei den Phycochromaceen. Forsch. Biol. Stat. z. Plén, 4: 189-206. 1899. Die Befruchtung von Sphaeroplea annulina Ag. Festschr. f. Schwendener, 1899: 81-103; Pl. 5. KLEBAnN, H., and LemMEerMaANN, E. 1895. Vorarbeiten zu einer Flora des Pléner Seengebietes. I. Forsch. Biol. Stat. z. Plon, 3: 1-17. Kress, G. 1881. Beitriage zur Kenntniss niederer Algenformen. Bot. Zeit., 39: 249-957, 265-272, 281-290, 297-308, 313-319, 329-336; Pls. 3,4. 1883. Ueber die Organisation einiger Flagellatengruppen und ihre Beziehungen zu Algen und Infusorien. Untersuch. a d. Bot. Inst. z. Tiibingen, 1: 233-862; [ 633 ] Pls. 2, 3. 1892. Zur Physiologie der Fortpflanzung von Vaucheria sessilis. Ver. d. Naturf. Ges. z. Basel, 10( Heft 1): 45-72. 1893. Flagellatenstudien. L-Il. Zeit. Wiss. Zool., 55: 265-351, 353-445; Pls. 17, 18. 1896. Die Bedin- gungen der Fortpflanzung bei einigen Algen und Pilzen. Jena. 1912. Ueber Flagellaten- und Algen- ahnliche Peridineen. Ver. Naturh. med. Vereins Heidelberg, 11(Heft 4): 367-451; Pl. 10; Figs. 1-15. 1928. Die Bedin- gungen der Fortpflanzung bei einigen Algen und Pilzen. Jena. KiercuER, J. 1896. Ueber zwei Wasserformen von Stichococcus. Flora, 82: pei . D. 1929. Notes on the life history of Tetraspora gelatinosa (Vauch. ) Desv. Arch. f. Protist., 66: 290-296; PI. 8. Koro, C. A. 1896. A report upon the Protozoa observed in Lake Michigan and the inland lakes in the neighborhood of Charlevoix, during the sum- mer of 1894. Appendix II. In: Michigan Fish Comm. Bull., 6: 3-93. Korom, C. A., and MicHENER, J. R. 1911. New genera and species of Dino- flagellates. Bull. Mus. Comp. Zool. (Harvard College), 54: 267-302. Korow, C. A., and Swezy, Oxive. 1921. The free-living or unarmored Dino- flagellata. Mem. Univ. Calif., 5: 1-562; Pls. 1-12; Figs. A-VV. Kotxwitz, R., and Kriecer, W. 1941. Zygnemales. In L. Rabenhorst, Krypto- gamen-Flora von Deutschland, Oesterreich und der Schweiz. 13, Abt. 2, Lief. 1/2. Leipzig. Korrre, Fritz. 1924. Die Schlammflora der ostholsteinischen Seen und des Bodensees. Arch. f. Hydrobiol., 14: 619-719. Korscuikov, A. A. 1917. Contribution a l’étude des algues de la Russie. Trav. Stat. Biol. Borodinskaja, 4: 219-267; Pl. 2. 1923. Zur Morphologie des geschlechtlichen Prozesses bei den Volvocales. (Russian with German sum- mary.) Arch. Russ. Protist. 2: 179-194. 1924. Zur Morphologie und Syste- matik der Volvocales. (Russian with German summary.) Ibid., 3: 45-56; Pl. 2. 1924a. Protistologische Beobachtungen. (Russian with German sum- mary.) Ibid., 3: 57-74. 1925. Beitrage zur Morphologie und Systematik der Volvocales. I, (Russian with German summary.) Ibid., 4: 153-197; Pls. 7-9. 1925a. Contribution 4 étude des algues de la Russie. Rech. algol. aux environs de la station Biol. Borodinskaja pendant ]’été 1925. 1927. On the validity of the genus Schizomeris Kiitz. (Russian with English summary. ) Arch. Russ. Protist., 6: 71-82; Pls. 5,6. 1928. On two new Spondylomor- aceae: Pascheriella tetras n. gen. et sp. and Chlamydobotrys squarrosa n. sp. Arch. f. Protist., 61: 233-238; Pl. 9; Figs. 1-5. 1928a. Notes on some new flagellates. (Russian and English.) Ibid., 7: 151-158. 19387. On the sexual reproduction (odgamy) in the Micractineae. Kharkov A. Gorky State Univ. Book No. 10( 1937): 109-126, 1941. On some new or little known flagellates. Arch, f. Protist., 95: 22-44, Korscuixov, A. A., and Anacuin, I. K. 1928. [Contribution to the study of the validity of Chlamydobotrys gracilis Korsch.]. (Russian with English sum- mary.) Arch. Russ. Protist., 7: 145-150. KossinsxajA, C. 1940. Die Algen des Neva Beckens. Akad. nauk S.S.R.R., Leningrad. Bot. Inst. Trudy, Ser. 2, Plantae Crypt. (Acta Inst. Bot. Acad. [ 634 | Sci. URSS), 4(1938): 83-106. 1940a. [Algae from the environments of Jukki]. (Russian with English summary.) Ibid., 4(1938): 107-130. Kozminsk1, Z. 1938. Amount and distribution of the chlorophyll in some lakes of northeastern Wisconsin. Trans. Wis. Acad. Sci., Arts and Letters, 31: 411-438. Kriecer, W. 1932. Untersuchungen iiber Plankton-Chrysomonaden. Die Gat- tungen Mallomonas und Dinobryon in monographischer Bearbeitung. Bot. Arch., 29: 257-329. Krocu, Aucust. 1931. Dissolved substances as food of aquatic organisms. Biol. Rev. and Biol. Proc. Cambridge Phil. Soc., 6: 412-442. Kurun, J. 1878. Ueber eine neue parasitische Alge, Phyllosiphon Arisari. Sitz. Natur. Ges. Halle, 1878: 24-26. Kueune, Paut E. 1941 The phytoplankton of southern and central Saskatche- wan. Part II. Can. Jour. Res., 19 (Sec. C): 318-322; Figs. 1-3. Kvuerzine, F. T. 1833. Algologische Mittheilungen. I. Ueber Gloionema Agh. II. Ueber eine neue Gattung der Confervaceen. Flora, 16: 513-528. 1833a. Beitrag zur Kenntniss iiber die Entstehung und Metamorphose der niedern vegetabilischen Organismen, etc. Linnaea, 8: 335-382. 1833b. Synopsis Diatomacearum oder Versuch einer systematischen Zusammenstellung der Diatomeen. Ibid., 8: 529-620. 1833-1835. Algarum dulcis germanicarum. Dec. I-XVI.-Halis Saxorum. 1835. Description de quelques nouvelles espéces de Chara. Ann. Sci. Nat. Bot., 3(Sér. 2): 64. 1839. Ueber ein neues Botrydium. Nova Acta Acad. Caes. Leop.-Carol., 19: 385. 1843.+ Phycologia generalis, oder Anatomie, Physiologie und Systemkunde der Tange. 458 pp.; Pls. 1-80. Leipzig. 1843a. Ueber die Systematische Eintheilung der Algen. Linnaea, 17: 75-107. 1845. Phycologia germanica, d. i. Deutschlands Algen in biindigen Beschreibungen. 340 pp. Nordhausen. 1847. Diagnosen und Bemerkungen zu neuen oder kritischen Algen. Bot. Zeit., 5: 164-167. 1846— 1871. Tabulae phycologicae oder Abbildungen der Tange. I-XIX; Pls. 1-1900. Nordhausen. 1849. Species algarum. 922 pp. Leipzig. Kurreratu, H. 1913. Contribution 4 la physiologie d’une Protococcacée nou- velle Chlorella luteo-viridis Chodat, nov. spec. var. lutescens Chodat, nov. var. Rec. Inst. Léo Errera, 9: 114-319; Figs. 1-28. 1914-1915. Contribu- tions 4 la flore du Luxembourg meridional. II. Chlorophycées (exclus. Desmidiacées), Flagellates et Cyanophycées. Ann. Biol. Lacustre, 7: 231- 271. Kurssanow, L. J., and SCHEMAKHANOVA, N. M. 1927. Sur la succession des phases nucléaire chez les algues vertes. I. Le cycle de développement du Chlorochytrium Lemnae Cohn. Arch. Russ. Protist., 6: 131-146; Pls. 9, 10; Figs. 1, 2. ae H. 1912. Studien iiber die schwedischen Arten der Gattungen Batracho- spermum Roth und Sirodotia nov. gen. Nova Acta. Reg. Soc. Sci. Upsala, 3(Ser. 4), No. 3: 1-40. 1917. Ueber die Entwicklungsgeschichte von Batrachospermum moniliforme. Ber. d. Deutsch. Bot. Ges., 35: 155-170. Lackey, JAMEs B. 1936. Some fresh water protozoa with blue chromatophores. Biol. Bull., 71: 492-497. 1939. Notes on plankton flagellates from the Scioto River. Lloydia, 2: 128-143. 1940. Limitations of Euglenidae as polluted water indicators. U. S. Publ. Health Rep., 55(No. 7): 268-280; Figs. 1-6. 1944.* Quality and quantity of plankton in the south end of Lake Michigan in 1942. Jour. Amer. Water Works Assoc., 36: 669-674; Figs. 1-7. LacrrHem, G. 1882. Bidrag till kannedomen om Stockholmstraktens Pedia- stéer, Protococcacéer och Palmellacéer. Oefv. Kongl. Sv. Vet.-Akad. Fér- handl., 39(No. 2): 47-81; Pls. 2,3. 1883. Bidrag till Sveriges algflora. Ibid., [ 635 ] 40(No. 2): 37-78; Pl. 1. 1884. Ueber Phaeothamnion, eine neue Gattung un- ter den Siisswasseralgen. Bih. Kongl. Sv. Vet.-Akad. Handl., 9( No. 19): 3-14; 1 pl. 1886. Algologiska bidrag. I. Contributions algologiques a la flora de la Suéde. Bot. Notiser, 1886: 44-50. 1887. Note sur /Uronema, nouveau genre des algues d’eau douce de l’ordre des Chlorozoosporacées. Malpighia, 1: 517— 523; Pl. 12. 1887a. Zur Entwickelungsgeschichte einiger Confervacéen. Ber. d. Deutsch. Bot. Ges., 5: 409-417. 1887b. Ueber einige Algen aus Cuba, Jamaica und Puerto-Rico. Bot. Notiser, 1887: 193-199. 1888. Sopra alcune alghe d’acqua dolce nuovo o rimarchevoli. Notarisia, 1888: 590-595. 1889. Studien iiber die Gattung Conferva und Microspora. Flora, 72: 179-210; Pls. 5, 6. 1890. Contribuciones a la flora algologica del Ecuador. I-II. Anal. Univ. Central de Quito, Ecuador, 4(1890-1891): 79-88. 1892. Die Schneeflora des Pichincha. Ber. d. Deutsch. Bot. Ges., 10: 517-534; Pl. 28. 1893. Chlorophyceen aus Abessinien und Kordofan. Nuova Notarisia, 4: 153-160. 1895. Studien wber die arktische Cryptogamen. 1. Ueber die Entwickelung von Tetraédron Kiitz. und Euastropsis Lagerh., eine neue Gattung der Hydrodictyaceen. Troms6 Mus. Aarschefter, 17(1894): 1-24. 1900. Vege- tabilisches Siisswasser-Plankton aus der Bareninseln (Beeren-Eiland). Bih. Kongl. Sv. Vet.-Akad. Handl., 26, Afd. 3, No. 11: 1-25. Lacuer, Karu. 1940. A turtle loss? Amer. Wildlife, 29: 41-44. 1943. Food habits and economic relations of the turtles of Michigan with special ref- erence to fish management. Amer. Mid]. Nat., 29: 257-312. Lampert, F. D. 1909. Two new species of Characium. Rhodora, 11: 65-74. Lapua, I. A. 1850.* Plants of Wisconsin. Proc. Amer. Assoc. Adv. Sci., 1849: 19-59. Larsen, E. 1904. The fresh water algae of East Greenland. Medd. om Gron- land, 30(B): 75-100. LauTERBORN, R. 1896. Diagnosen neuer Protozoen aus dem Gebiete des Oberrheins. Zool. Anz., 19: 14-18. 1899. Protozoenstudien. Flagellaten aus dem Gebiete des Oberrheins. Zeit. Wiss. Zool., 65: 365-391; Pls. 17, 18. 1913. Zur Kenntnis einiger sapropelischer Schizomyceten. Allg. Bot. Zeitschr., 19: 97-100. 1913a. Siisswasserfauna. Handwort. Naturwiss., 9: 861-920. 1914-1917. Die Sapropelische Lebewelt. Ver. Natur. mediz. Ver. Heidel- berg, 13: 395-481. Leake, Dorotuy V. 1938. Preliminary note on the production of motile cells in Basicladia. Proc. Okla. Acad. Sci., 19: 109-110. Lesour, Marie V. 1925. The dinoflagellates of northern seas. Plymouth, Eng. Lerevre, M. 1925. Contribution a la flore des algues d’eau douce du nord de la France. Bull. Soc. Bot. France, 72 (Vol. 1, Ser. 5): 689-699. 1932. Monographie des espéces d’eau douce du genre Peridinium. Arch. d. Bot., 2(1928, Mém. 5): 1-210. 1932a. Sur la structure de la membrane des Eug- lénes du groupe, Spirogyra. Comp. Rend. Acad. Sci. Paris, 195: 1308-1309. LEFEVRE, M., and BourreLuy, P. 1939. Sur la stabilité de ornamentation chez les espéces du genre Pediastrum Meyen. Comp. Rend. Acad. Sci. Paris, 208: 368-370. LEMMERMANN, E. 1895. Verzeichnis der in der Umgegend von Ploen ges- ammelten Algen. Forsch. Biol. Stat. z. Plon, 3: 18-67. 1896. Zweiter Beitrag zur Algenflora des Pléner Seengebietes. Ibid., 4: 134-188. 1896a. Zur Algenflora des Riesengebirges. Ibid., 4: 88-133. 1897. Die Planktonalgen des Miiggelsees bei Berlin. II. Zeit. f. Fisch., 1897: 177-188. 1897a. Resultate einer biologischen Untersuchungen von Forellenteichen. Forsch. Biol. Stat. z. Plon, 5: 67-114. 1898. Der grosse Waterneverstorfer Binnensee. Eine biologische Studie. Ibid., 6: 166-204. 1898a. Beitrag zur Algenflora von [ 636 ] Schlesien. Abh. Natur. Ver. Bremen, 14(1897): 241-263; Pl. 1. 1898b. Algologische Beitrage. IV—V. Ibid., 14: 501-512; Pl. 5. 1898c. Beitrage zur Kenntniss der Planktonalgen. I. Golenkinia Chodat, Richteriella Lemm., Franceia nov. gen., Phythelios Frenzel, Lagerheimia Chodat, Chodatella nov. gen., Schroederia nov. gen. Hedwigia, 37: 303-312; Pl. 10. 1898d. Beitrage zur Kenntniss der Planktonalgen. II. Beschreibung neuer Formen. Bot. Centralbl., 76: 150-156. 1899.t Das Genus Ophiocytium Naegeli. Hedwigia, 38: 20-38; Pls. 3,4; Figs. 15-18. 1899a. Das Phytoplankton sachsischer Teiche. Forsch. Biol. Stat. z. Plon, 7: 96-140; Pls. 1,2. 1900. Ergebnisse einer Reise nach dem Pacific (H. Schauinsland 1896-1897 ) Planktonalgen. Abh. Natur. Ver. Bremen, 16(1899): 313-398. 1900a. Beit- rige zur Kenntniss der Planktonalgen. III. Neue Schwebalgen aus der umgegend von Berlin. Ber. d. Deutsch. Bot. Ges., 18: 24-32. 1900b. Beitrage zur Kenntniss der Planktonalgen. IV. Die Coloniebildung von Richteriella botryoides (Schmidle) Lemm. Ibid., 18: 90-91; Pl. 3. 1900c. Beitrage zur Kenntniss der Planktonalgen. VIII. Peridiniales aquae dulcis et submarinae, Hedwigia, 39: [115-121]. 1900d. Beitrage zur Kenntniss der Planktonalgen. VI. Das Phytoplankton brackischer Gewasser Ber.d.Deutsch.Bot.Ges.,18:90—94. IX. Lagerheimia Marssonii nov. spec., Centratractus belonophora (Schmidle ) nov. gen. et sp., Synedra limnetica nov. spec., Marssoniella elegans nov. gen. et sp. Ber. d. Deutsch. Bot. Ges., 18: 272-275. 1900e. Beitrage zur Kennt- niss der Planktonalgen. XI. Die Gattung Dinobryon Ehrenb. Ibid., 18: 500- 524; Pls. 18,19. 1901. Beitriége zur Kenntniss der Planktonalgen. XII. Noti- zen iiber einige Schwebalgen. Ibid., 19: 85-92. 1901la. Beitrage zur Kennt- niss der Planktonalgen. XIII. Das Phytoplankton des Ryck und des Greifs- walder Boddens. Ibid., 19: 92-95. 1901b. Beitrage zur Kenntniss der Planktonalgen. XIV. Neue Flagellaten aus Italien. Ibid., 19: 340-348. 1901c. Zur Kenntnis der Algenflora des Saaler Boddens. Forsch. Biol. Stat. z. Plon, 8: 74-85. 1901d. Algenflora eines Moortiimpels bei Plén. Ibid., 8: 64-73. 1902. Bericht der Commission fiir die Flora von Deutschland. VI. Algen des Siisswassers. Ber. d. Deutsch. Bot. Ges., 20: [243-253, 257-263]. 1903. Beitrage zur Kenntnis der Planktonalgen. XV. Das Phytoplankton einiger Pléner Seen. Forsch. Biol. Stat. z. Plon, 10: 116-176. 1903a. Brandenbur- gische Algen. Hedwigia, 42: [168-169]. 1903b. Brandenburgische Algen. II. Das Phytoplankton des Miiggelsees und einer benachbarter Gewasser. Zeit. f. Fisch., 11(Heft 2): 73-123. 1903c. Beitriége zur Kenntnis der Planktonalgen. XVI. Phytoplankton voh Sandhem (Schweden). Bot. Notiser, 1903: 65-69. 1903d. Das Phytoplankton des Meeres. II. Beitrag. Abh. Natur. Ver. Bremen, 17: 341-418. 1904. Das Plankton schwedischer Gewas- ser. Arkiv f. Bot., 2, No. 2(1903+1904): 1-209; Pls. 1,2. 1904a. Beitrage zur Kenntnis der Planktonalgen. XIX. Das Phytoplankton der Ausgrabenseen bei Plén. Forsch. Biol. Stat. z. Plon, 11: 289-311; Figs. 1-17. 1904b. Beitrige zur Kenntnis der Planktonalgen. XVIII. Ueber die Entstehung neuer Planktonformen. Ber. d. Deutsch. Bot. Ges., 22: 17-22. 1905. Branden- burgishe Algen. III. Neue Formen. Forsch. Biol. Stat. z. Plon, 12: 145-153. 1905a. Beitrage zur Kenntnis der Planktonalgen. XX. Phytoplankton aus Schlesien. Ibid., 12: 154-163. 1905b. Beitrige zur Kenntnis der Planktonalgen. XXI. Das Phytoplankton siichsischer Teiche. Zweiter Beitrag. Ibid., 12: 164— 168. 1905c. Die Algenflora der Sandwich-Inseln. Ergebnisse einer Reise nach dem Pacific. H. Shauinsland 1896/97. Engler. Bot. Jahrb., 34: 607-663; Pls. 7, 8. 1906. Ueber die von Herrn Dr. Walter Volz auf seiner Weltreise ,gesammelten Siisswasseralgen. Abh. Natur. Ver. Bremen, 18 (1905-1906 ): 143-174; Pl. 11. 1906a. Das Phytoplankton des Meeres. Beih Bot. Centralbl., [ 637 ] 19(Heft 2): 1-74. 1906b. Beitrage zur Kenntnis der Planktonalgen. Ber. d. Deutsch. Bot. Ges., 24: 535-538. 1906c. Uber das Vorkommen von Siisswas- serformen in Phytoplankton des Meeres. Arch. f. Hydrobiol. u. Planktonk., 1: 409-427. 1907. Das Plankton der Weser bei Bremen. Ibid., 2: 393-447. 1907a. Das plankton des Jang-tse-Kiang (China). Ibid., 2: 534-544. 1907b. Bran- denburgische Algen. IV. Gonyaulax palustris, eine neue Siisswasser-Peridinee. Beih. Bot. Centralbl., 21: 296-300. 1907-1910.t Kryptogamenflora der Mark Brandenburg. Algen. I. Leipzig. 1908. Algologische Beitrage. VI. Algen aus der Biviera von Lentini (Sizilien). VII. Ueber Scheidenbildung bei Oscillatoria Agardhii Gomont. VII. Zur Algenflora des Anapo. IX. Neue Schizophyceen. X. Die Micrasterias-Formen des Kénigreichs Sachsen. XI. Oedogonium cardiacum var. minor Lemm. nov. var. Arch. f. Hydrobiol. u. Planktonk., 4: 165-192; Pl. 5. 1908a. Beitrage zur Kenntnis der Plankton- algen. XXIII. Das Phytoplankton des Lago di Varano und des Lago di Monate (Italien). Ibid., 3: 349-886; Figs. 1-25. 1908b. Beitrage zur Kenntnis der Planktonalgen. XXIV. Plankton aus Schlesien. 2 Beitrag. Ibid., 3: 386-404; Figs. 26-35. 1908c. Beitriige zur Kenntnis der Planktonalgen. XXV. Die Algen Stralsunder Rohwassers. Ibid., 3: 404-410; Figs. 86-40. 1908d. Das Phytoplankton des Menam. Hedwigia, 48: 126-189. 1910 (1907-1910). Kryptogamenflora der Mark Brandenburg. Algen. I. Leipzig. 1913.+ Euglenineae. Flagellatae II. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 2. Flagellatae 2: 115-174; Figs. 181-377. Jena. 1914. Algologische Beitrige. XII. Die Gattung Chara- ciopsis Borzi. Abh. Natur. Ver. Bremen, 23: 249-261; Figs. 1-14. 1915.+ Tetrasporales. In A. Pascher, Die Siisswasserflora Deutschlands. Oesterreichs und der Schweiz. Heft 5. Chlorophyceae 2: 21-51; Figs. 1-33. Jena. Lreonnarpi, H. von. 1863. Die boéhmischen Characeen. Lotos, 18: 55-80, 110-111. Levanper, K. M. 1900. Der Kenntniss der Lebens in den stehenden Kleinige- wissern auf den Skireninseln. Acta Soc. Fauna et Flora Fenn., 18(No. 6): 1-107. 1901. Beitrage zur Fauna und Algenflora der sussen Gewasser an der Murmankiiste. I[bid., 20( No. 8): 1-35. LEvERETT, FRANK. 1911. Surface geology of the Northern Peninsula of Mich- igan. Mich. Geol. and Biol. Surv. Publ. No. 5: 1-86. 1917. Surface geology and agricultural conditions of Michigan. Ibid., No. 25(Geol. Ser. 21): 1-223. Lewss, I. F. 1913.* Chlorochromonas minuta, a new flagellate from Wisconsin. Arch. f. Protist., 32: 249-256; Pl. 12. 1925. A new conjugate from Woods Hole. Amer. Jour. Bot., 12: 351-357; Pls. 36, 37. Lewis, I. F., Zmkie, C., and Parricx, Ruru. 1933. Algae of Charlottesville and vicinity. Jour. Elisha Mitchell Sci. Soc., 48: 207-222. Ley, S. H. 1947. Heleoplanktonic algae of North Kwangtung. Bot. Bull. Acad. Sinica, 1: 270-282; Figs. la—lh. Li, L. C. 1933. New species and varieties of freshwater algae from China. Ohio Jour. Sci., 33: 151-154. LirpMann, F. 1841. Bemiirkninger og Tillag til den danske Algeflora. Kroyers Tidsk., 1841. Kjobenhavn. 1841a. Algologisk Bidrag. Kjobbenhavn. (Not seen.) Littey, Gene. 1903. Nitella batrachosperma in Minnesota. Minn. Bot. Studies, 3: 79-82; Pl. 18. Liuicx, Lois C. 1935.,A new species of Spirulina. Amer. Midl. Nat., 16: 210-211; Figs. 1A-ID. LinpEMAN, RayMonp L. 1941. Seasonal food cycle dynamics in a senescent lake. Amer. Midl. Nat., 26: 636-673. 1942. The trophic-dynamic aspect of ecology. Ecology, 23: 399-418. [ 638 | LINDEMANN, E. 1925. Ueber finnische Peridineen. Arch. f. Hydrobiol. u. Plank- tonk., 15: 1-4. 1928. Vorlaufige Mitteilung. Arch. f. Protist., 63: 259-260. 1928a. Peridineae (Dinoflagellatae). In A. Engler and K. Prantl, Die Natiirlichen Pflanzenfamilien. 2: 1-104; Figs. 1-92. 2nd. ed. Leipzig. Linx, H. F. 1809. Nova plantarum genera e classe Lichenum, Algarum, Fun- gorum. Schrader’s Neue Journal f. die Botanik, 3(Stiick 1): 1-19. 1820. Epistola de Algis aquaticis in genera disponendis. In C. G. H. Nees von Esenbeck, Horae physicae berolinenses, pp. 1-8. 1833. Handbuch zur Erkennung der nutzbarsten und am haufigsten vorkommenden Gewachse, Dritter Teil. Berlin. LinnaEus, Cart von. 1737. Genera plantarum. Leiden. 1753. Species plant- arum. Stockholm., 1754. Genera plantarum. 5th ed. 1758. Systema naturae. Regnum animale. Vol. I. 10th ed. Leipzig. Losi, A. I. 1915. Catalogue des algues d’eau douce recueillies au Caucase ar A. A. Elenkin et V. P. Savicz dans la région Czernomorsk pendant Pété 1912. Bull. Jard. Imp. Bot. Pierre le Grand, 15(No, 1): 23-47. Louman, H. 1911. Ueber das Nannoplankton und die Zentrifugierung kleinster Wasserproben zur Gewinnung desselben in lebenden Zustande. Inter. Rev. Ges. Hydrobiol. u. Hydrogr., 4(Pt. 1/2): 1-38. LoisELEUR-DEsLoNccHamMps, J. L. A. 1810. Notice sur les plantes a ajouter 3 la flore de France, pp. 135-139. Paris. Lowe, C. W. 1927. Some freshwater algae of southern Quebec. Trans. Roy. Soc. Canada, 5: 291-316. Lucxs, R. 1907. Zur Kenntnis der westpreussischen Pediastrumarten. Jahrb. d. Westpr. Lehrevereins f. Naturk., 1906-1907: 31-49. Lunp, J. W. G. 1947. Observations on soil algae. III. Species of Chlamydomo- nas Ehr. in relation to variability within the genus. New Phytol., 46(2): 185-194; Figs. 1-3. Lyman, F. E. 1936.* Plankton of inland waters. Mich. State College Agric. Appl. Sci. Eng., Exper. Sta., Bull. No. 66: 20-24. LyncByeE, H. Cu. 1819. Tentamen Hydrophytologiae Danicae. Kjobenhavn. MacmiLan, Conway. 1894. Sphaeroplea annulina in Minnesota. Bot. Gaz., 19: 246. Macnus, P. 1883. Das Auftreten von Aphanizomenon flos-aquae (L.) Ralfs in Eise bei Berlin. Ber. d. Deutsch. Bot. Ges., 1: 129-132. Mainx, F. 1926. Einige neue Vertreter der Gattung Euglena Ehr. Arch. f. Protist., 54: 150-182. 1928. Beitrige zur Morphologie und Physiologie der Eugleninen. I. Ibid., 60: 305-414; Pl. 10. Mancin, L. 1911. Modifications de la curiasse chez quelques Péridiniens. Inter. Rev. Ges. f. Hydrobiol. u. Hydrogr., 4: 44-54; Plsaeieo: Mannine, W. M., and Jupay, C. 1941. The chlorophyll content and product- ivity of some lakes in northeastern Wisconsin. Trans. Wis. Acad. Sci., Arts and Letters, 33: 363-393. Manninc, W. M., Jupay, C., and Woir, MICHAEL. 1938. Photosynthesis of aquatic plants at different depths in Trout Lake, Wisconsin. Trans. Wis. Acad. Sci., Arts and Letters, 31: 377-410. Marsu, C. D: 1903.* The plankton of Lake Winnebago and Green Lake. Bull. Wis. Geol. and Nat. Hist. Surv., 12, Sci. Ser., No. 3: 1-94. MarsHat, F. T., and Hacue, S. M. 1938. Basicladia in Illinois. Trans. Il. Acad. Sci., 31: 111-112. Martwus, C. F. P. von. 1817. Flora cryptogamica Erlangensis. Nuremberg. MaskELL, W. M. 1887. On the fresh-water infusoria of the Wellington district. Trans. N. Z. Inst., 20: 3-19. [ 639 ] Masser, G. 1891. Life-history of a stipitate freshwater alga. Jour. Linn. Soc. Bot., 27: 457-462. Menecuint, G. 1837. Conspectus algologiae euganeae. 37 pp. Patavia. 1840. Synopsis Desmidiacearum hucusque cognitarum. Linnaea, 14: 201-240. 1842. Monographia Nostochinearum italicarum. Aug. Taurinorum. (Not seen. ) MessikoMMER, Ep. 1927. Biologische Studien im Torfmoor von Robenhausen unter besondere Beriicksichtigung der Algenvegetation. Mitt. Bot. Mus. Univ. Zurich, 122: 1-171. Meunier, A. 1919. Microplankton de la Mer Flamande. Part II. Les Péri- diniens. Mém. Mus. Roy. Hist. Nat. Belgique, 8(No 1): 1-116. Meyen, F. J. F. 1829. Beobachtungen iiber einige niedere Algenformen. Nova Acta Acad. Caes. Leop.-Carol., 14: 768-778. 1838. Neues System Pflanzen- Physiologie. Bd. 2. Berlin. 1839. Jahresberichte iiber die Resultate der Arbeiten im Felde der physiologischen Botanik von dem Jahre 1838. Arch. f. Naturg., 2: 1-153. Meyer, A. 1895. Ueber den Bau von Volvox aureus Ehrenb. und Volvox globator Ehrenb. Bot. Centralbl., 63: 225-233; Figs. 14. 1896. Die Plas- maverbindungen und die Membranen von Volvox globator, aurens und tertius mit Riicksicht auf die thierischen Zellen. Bot. Zeit., 54: 187-217; Pl. 8; Figs. 1-7. Meyer, C. I. 1922. Algae nonnullae novae baicalenses. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 1(No. 1): 13-15. 1930. Einige neue Algenformen des Baikalsees. Arch. f. Protist., 72: 158-172. Meyer, K. I. (See Meyer, C. I.) Micuta, W. 1907. In Thome, Kryptogamen-Flora Deutschland, Deutsch- Oesterreich und der Schweiz, 6, Kryptogamen 2, Algen 1. Gera. Miter, V. V. 1923. Zur Systematik der Gattung Anabaena Bory. Arch. Russ. Protist., 2: 116-126; Figs. 1-5. Moestvus, M. 1888. Beitrag zur Kenntniss der Algengattung Chaetopeltis Ber- thold. Ber. d. Deutsch. Bot. Ges., 6: 242-248; Pl. 12. 1888a. Ueber einige in Portorico gesammelte Siisswasser- und Luft-Algen. Hedwigia, 27: 221- 249. 1889. Bearbeitung der von H. Schenck in Brasilien gesammelten Algen. Ibid., 28: 309-847. 1892. Australische Siisswasseralgen. Flora, 75: 421-450. 1894. Australische Siisswasseralgen. II. Abh. Senck. Natur. Ges. Frankfurt A. M., 18: 309-350. 1895. Beitrag zur Kenntniss der Algengattung Pitho- phora. Ber. d. Deutsch. Bot. Ges., 18: 356-361. Moewvus, Franz. 1935. Ueber einige Volvocalen aus dem Geogenfelder Moor (Erzgebirge). Sitz. Abh. Naturwis. Ges. Isis in Dresden, 1933-1934: 45-51; Figs. 1-6. 1936. Neue Volvocalen aus der Umgebung von Coimbra ( Portu- gal). Bol. Soc. Broteriana, 10: 1-14; Figs. 1-6 (reprint). Mouiscu, H. 1896. Die Ernéhrung der Algen (Siisswasseralgen II. Abhand- lung). Sitz. Kais. Akad. Wiss. in Wien, Math.-Nat. KI., 105(Abt. 1): 633-648. Moore, G. T. 1897. Notes on Uroglena americana. Bot. Gaz., 23: 105-112; Pl. 10. 1900. New or little known unicellular algae. I. (Chlorocystis Cohnii}. Ibid., 30: 100-112. 1901. Ibid. II. (Eremosphaera viridis, Excéntrosphaera). Ibid., 32: 309-325. 1917. Chlorochytrium gloeophilum Bohlin. Ann. Missouri Bot. Gard., 4: 271-278; Pl. 18. Moores, G. T., and Carrer, NEE. 1923. Algae from lakes in the north- eastern part of North Dakota. Ann. Missouri Bot. Gard., 10: 393-422; Pl. 21. Moore, G. T., and KetLermann, K. F. 1904. A method of destroying or preventing the growth of algae and certain pathogenic bacteria in water [| 640 | supplies. U. S. Dept. Agric., Bur. Plant Indust., Bull. 64. Washington. 1905. Copper as an algacide and disinfectant in water supplies. Ibid., Bull. 76. Washington. Morosowa-WopyanirzkajA, N. W. 1925. Dichomologischen Reihen als Grund- lage zur Klassification der Gattung Pediastrum Meyen. Russkii Ark. Protot., 4(No. 1/2): 5-81. MorreN, Cu. 1830. Mémoire sur un végétal microscopique d’un nouveau genre, proposé sous le nomme Microsoter, ou conservateur des petites choses. Ann. Sci. Nat. Bot., 20(Sér. 1): 404-426. 1838. Recherches physiologiques sur les hydrophytes de la Belgique. Premier Mémoire. Histoire d'un genre nouveau de la tribu Confervées, nommé par lauteur, Aphanizomene. Mém. Acad. Roy. Belgique, 11: 5-20 (in unnumbered memoirs in vol. )eal spk Muetter, O. F. 1773. Vermium terrestrium et fluviatilium. Hauniae, Faber. 1776. Zoologiae Danicae prodromus, seu animalium Daniae et Norvegiae indigenarum characteres, nomina et synonyma imprimis populorium. Havnia, Hallogeriis. 1786. Animalicula infusoria, fluviatilia et marina. Hafniae et Lipsiae. wigan GrorcE. 1892-1895.* Calcareous pebbles formed by algae. Phycol. Mem., Part II( No. 13): 74-77. Nagcet, C. W. 1847. Die neuern Algensysteme und Versuch zur Begriindung eines eignen Systems der Algen und Florideen. Zurich. 1849.+ Gattungen einzelligen Algen, physiologische und systematische bearbeitet. 137 pp.; Pls. 1-8. Zurich. Namystowsk1, B. 1921. Studja Hydrobiologiczne. HII. Prace Koniisji Matew.- Przyrod. Tow. Pizyinc. Nauk. w. Pozanaiu. Ser. B. 1, z. 1(1921). Poznan. (Not seen. ) Naya . See El-Nayal. NEEDHAM, J. G., and Luoyp, J. T. 1916. The life of inland waters. Ithaca, N. Y. NEEDHAM, J. G., and NEEDHAM, P. R. 1938. A guide to the study of fresh- water biology with special reference to aquatic insects and other inverte- brate animals and phytoplankton. 4th ed. Ithaca, N. Y. NEEL, J. K. 1948.* A limnological investigation of the psammon in Douglas Lake, Michigan, with especial reference to shoal and shoreline dynamics. Trans. Amer. Microsc. Soc., 67: 1-53. Nicnots, G. E., and AcxLry, ALMa B. 1932.* The desmids of Michigan with particular reference to the Douglas Lake region. Pap. Mich. Acad. Sci., Arts, and Letters, 15( 1931): 113-140. Nisuimura, M. 1923. The theory of the spherical thallus formation of Aega- gropila Sauteri (Nees) Kuetz. Bot. Mag. Tokyo, 37: 62. Norpstept, [C. F.] O. 1876. In C. F. O. Nordstedt & V. Wittrock. 1876. I Desmidieae (Kiitz.) De Bar. Oef. Kongl. Sv. Vet-Akad. Forhandl., 33 (No. 6): 25-44. 1877. Bohuslans Oedogonieer. Ibid., 34( No. 4) 21-38. 1878. De Algis aquae dulcis et de Characeis ex insulis sandvicencibus a Sv. Berggren 1875 reportatis. Minnesskr. Fys. Sallsk. Lund, 7: 1-24; Pls. 1,2. 1879. Algologiska smisaker, II. Vaucheria-studier. 1879. Bot. Notiser, 1879: 177- 190. 1888. Freshwater algae collected by Dr. S. Berggren in New Zealand and Australia. Bih. Kongl. Sv. Vet.-Akad. Handl., 22(No. 8): 1-98. 1891. On the value of original specimens (translated from Botaniska Notiser, 1891: 76-82). Nuova Notarisia, 1891: 449-454. Norpstept, C. F. O., and Wirrrocx, V. 1876. Desmidieae et Oedogonieae ab O. Nordstedt in Italia et Tyrolia collectae, quas determinaverunt. Oef. Kongl. Sv. Vet.-Akad. Foérhandl., 33(No. 6): 25-56; Pls. 12, 18. Nowaxowsk1, L. 1877. Beitrag zur Kenntnis der Chytridiaceen. Beitr. Biol. Pflanzen, 2( No. 1): 73-100. [ 641 ] Nycaarp, G. 1932. Contributions to our knowledge of the freshwater algae and phytoplankton from the Transvaal. Trans. Roy. Soc. S. Africa, 20: 101-148. 1949. Hydrobiological studies on some Danish ponds and lakes. Kongl. Danske Vid. Selsk. Biol. Skrift., 7( No. 1): 1-293; 126 figs. OerstTeED, A. S. pE. 1842. Beretning om en Excursion til Trindelen, en alluvi- aldannelse i Odensefjord. Kjobenhavn. Onasui, H. 1926. Oedogonium nebraskensis (sic), sp. nov. Bot. Gaz., 82: 207-214; Figs. 1-20. Otive, Epcar W. 1905.* Notes on the occurrence of Oscillatoria prolifica (Greville) Gomont in the ice of Pine Lake, Waukesha County. Trans. Wis. Acad. Sci., Arts and Letters, 15(Pt. 1): 124-134. OLrManns, F. 1922.+ Morphologie und Biologie der Algen. Vol. 1: 1-459; Figs. 1-287; Vol. 2: 1-439; Figs. 288-612; Vol. 3: 1-558; Figs. 613-797. 2nd ed. Jena. Osorio TaraLy, B. F. 1941. Materiales para el estudio del microplankton del Lago de Patzcuaro (México). I. General idades y fitoplankton. Anal. Escuela Nac. Cien. Biol. (México), 2: 331-382. OsTENFELD, C. H. 1907. Beitrage zur Kenntnis der Algenflora des Kosogol- Beckens in der nordwestlichen Mongolei, mit spezieller Beriichsichtigung des Phytoplanktons. Hedwigia, 46: 365-420. 1909. Notes on the phyto- plankton of Victoria Nyanza, East Africa. Bull. Mus. Comp. Zool. (Harvard College), 52(No. 10): 171-181. OsTENFELD, C. H., and Nycaarp, G. 1925. On the phytoplankton of the Gatun Lake, Panama Canal. Dansk Bot. Arch., 4: 1-16; Figs. 1-20. Oye, P. van. 1924. Note sur Euglena acus Ehrenberg. Bull. Soc. Bot. Belgique, 56, Fasc. 2(1921-1923): 124-182. Pauia, E. 1894. Ueber eine neue, pyrenoidlose Art und Gattung der Conju- gaten. Ber. d. Deutsch. Bot. Ges., 12: 228-236; Pl. 18. Patmer, C. Mervin. 1941. A study of Lemanea with notes on its distribution in North America. Butler Univ. Studies, 5: 1-26; Figs. 1-4. Parmer, T. C. 1905. Delaware valley forms of Trachelomonas. Proc. Acad. Nat. Sci. Phila., 57: 665-675. 1925. Trachelomonas: New or notable species and varieties. Ibid., 77: 15-22. Papenruss, G. F. 1946. Proposed names for the phyla of algae. Bull. Torr. Bot. Club, 73(3): 217-218. Pascuer, A. 1909. Einige neue Chrysomonaden. Ber. d. Deutsch. Bot. Ges., 27: 247-254. 1910.’ Neue Chrysomonaden aus den Gattungen Chrysococcus, Chromulina, Uroglenopsis. Oesterr. Bot. Zeit., 60: 1-5. 1912. Eine farblose, rhizopodiale Chrysomonade. Ber. d. Deutsch. Bot. Ges., 30: BP alee TAL 6. 1912a. Ueber Rhizopoden-und Palmellastadien bei Flagellaten (Chrysomona- den), nebst einer Ubersicht iiber die braunen Flagellaten. Arch. f. Protist., 25: 153-200; Pl. 9; Figs. 1-7. 1912b. Zur Kenntnis zweier Volvokalen. Hedwigia, 52: 274-287. 1913.+ Chrysomonadineae, Cryptomonadineae. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 2. Flagellatae 2: 7-95; Figs. 1-150. Jena. 1913a. Die Heterokonten- gattung Pseudotetraédron. Hedwigia, 53(1912): 1-5; Figs. 1-6. 1913b. Zur Gliederung der Heterokonten. Ibid. 53(1912): 6-22. 1914. Ueber Symbiosen von Spaltpilzen und Flagellaten mit Blaualgen. Ber. d. Deutsch. Bot. Ges., 32: 339-352. 1914a. Ueber Flagellaten und Algen. Ibid., 32: 136-160. 1921. Ueber die Ubereinstimmungen zwischen den Diatomeen, Heterokonten und Chrysomonaden. Ibid., 39: 236-248; Figs. 1-6. 1925. Heterokontae, Phaeo- phyta. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heterokontae, Phaeophyta, Rhodophyta, Charophyta. Heft 11: [ 642 J 1-118; Figs. 1-96. 1925a. Neue oder wenig bekannte Protisten. XV. Arch. f. Protist., 50: 486-510. 1925b. Die braune Algenreiche der Chrysophyceen. Ibid., 52: 489-564. 1927. Volvocales-Phytomonadinae. In A. Pascher, Die Siisswasserflora Deutschlands, Oesterreichs und der Schweiz. Heft 4: 1-506; Figs. 1-45. Jena. 1927a. Neue oder wenig bekannte Protisten. XX. Arch. f. Protist., 58: 577-598. 1927b. Die braune Algenreiche aus der Ver- wandtschaft der Dinoflagellaten (Dinophyceen ). Ibid., 58: 1-54; Figs. 1-38. 1930. Zur Kenntnis der heterokonten Algen. Ibid., 69: 401-454; Pl. 21; Figs. 1-45. 1930a. Berichtigung zum Aufsatze: Zur Kenntnis der heterokonten Algen. Ibid., 69: 666. 1930b. Ein griiner Sphagnum-Epiphyt und seine Beziehung zu freilebenden Verwandten (Desmatractum, Calyptobactron, Bernardinella). Ibid., 69: 637-658. 1932. Einige neue oder Kritische Hetero- konten. Ibid., 77(No. 2): 305-359. 1932a. Zur Kenntnis mariner Plankton- algen. I. Meringosphaera und ihre Verwandten. Ibid., 77(No. 2): 195-218. 1932b. Ueber eine in ihrer Jurgend rhizopodial und animalisch lebende epi- phytische Alge (Perone). Beih. Bot. Centralbl., 49( Abt. 1): 675-685; Figs. 1-7. 1937-1939. Heterokonten. In L. Rabenhorst, Kryptogamen-Flora von Deutschland, Oesterreich und der Schweiz. XI: 1-1092; Figs. 1-912. Leipzig. 1940. Zur Kenntnis der Siisswassertetrasporalen I. Beih. Bot. Centralbl., 60A: 185-156; Pl. 4; Figs. 1-22. Pascuer, A., and LEMMERMANN. E. 1913. (See Pascher, 1913.) Pascuer, A., and Scuitter, J. 1925. (See Pascher, 1925.) Pavitiarp, J. 1923. A propos de la systématique des Péridiniens. Bull. Soc. Bot. France, 70: 876-882. PearsaLt, W. H. 1924. Phytoplankton and environment in the English lake district. Rev. Algol., 1: 53-67. Prestes, F. 1909. The life history of Sphaerella lacustris (Haematococcus pluvialis) with especial reference to the nature and behaviour of the zoo- spores. Centralbl. Bakt., 24: 18-22, 511-521. Penarp, C. 1891. Les Péridiniacées du Lac Leman. Bull. Trav. Soc. Bot. Genéve, 6: 1-63. PenHALLow, D. P. 1896.* Note on calcareous algae from Michigan. Bot. Gaz., 21; 215-217. Pennak, Rosert W. 1939. The microscopic fauna of the sandy beaches. In Problems of Lake Biology. Amer. Assoc. Adv. Sci., Publ. No. 10: 94-106. Perty, M. 1849. Ueber verticale Verbreitung mikroskopischer Lebensformen. Natur. Ges. in Bern Mitt., 1849: 17-45. 1852. Zur Kenntniss kleinster Lebens- formen nach Bau, Funktionen, Systematik, mit Specialverzeichnis der in der Schweiz beobachteten. Bern. PETERSEN, C. G. Jou., and PETERSEN, P. BoysEN. 1911. Valuation of the sea. I. Animal life of the sea bottom, its food and quantity. Rep. Danish Biol. Sta. to Bd. Agric., 20: 1-76. Petr, P. 1880. Spirogyra des environs de Paris. Paris. Perxorr, St. 1914. Les Characées de Bulgarie. Nuova Notarisia, 25: 35-56. Purtson, P. J. 1939. Freshwater algae of North and South Carolina. Part 1 Cyanophyceae. Jour. Elisha Mitchell Sci. Soc., 55: 83-116. Puinney, Harry K: 1943.* The filamentous algae of northern Michigan. M. A. thesis. Albion College. 1945. Notes on Cladophora. Amer. Midl. Nat., 84: 445. 1946.* A peculiar lake sediment of algal origin. Ibid., 35: 453-459. Pieters, A. J. 1894.* Plants of Lake St. Clair. Bull. Mich. Fish. Comm., No. we NII be Piayrarr, G. I. 1915. Freshwater algae of the Lismore district with an appen- dix on the algal fungi and Schizomycetes. Proc. Linn. Soc. N. S. Wales, 40: 310-362; Pls. 41-46. 1916. The genus Trachelomonas. Ibid., 40(1915): [ 643 ] 1-41. 1916a. Oocystis and Eremosphaera. Ibid., 41: 107-147; Pls. 7-9; Figs. 1-28. 1917. Australian freshwater phytoplankton. Ibid., 41: 823-852; Pls. 56-59. 1918. New and rare freshwater algae. Ibid., 43: 497-543; Pls. 54-58; Figs. 1-11. 1920. Peridineae of New South Wales. Ibid., 44( 1919): 793-818; Pls. 41-43; Figs. 1-18. 1921. Australian freshwater flagellates. Ibid., 46: 99-146; Pls. 1-9; Figs. 1,2. 1923. Notes on freshwater algae. Ibid., 48: 206-228; Figs. 1-30. PocuMan, A. 1942. Synopsis der Gattung Phacus. Arch. f. Protist., 95(No. 2): 81-252; Figs. 1-170. Pococx, Mary A. 1933. Volvox and associated algae from Kimberly. Ann. S. African Mus., 16: 473-521. 1933a. Volvox in South Africa. Ibid., 16: 523-646. Porjansky, G. I. 1923. De nova Euglenarum specie. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 1(1922): 177-183. Potiock, J. E. 1942.* Blue-green algae as agents in the deposition of mar] in Michigan lakes. Ann. Rep. Mich. Acad. Sci., 20: 247-260; Pls. 16. 17. Porzcrr, J. E. 1942.* Study on the rooted aquatic vegetation of Weber Lake, Vilas County, Wisconsin. Trans. Wis. Acad. Sci., Arts, and Letters, 34: 149-166; Figs. 1-3. Poutron, E. 1926.+ Etude sur les Heterokontées. Thesis, Univ. Genéve, Class. Sci. Ser. 10, Fasc. 11: 96 pp.; Figs. 1-13. Powers, E. B., Suretps, A. R., and Hickman, M. E. 1939. The mortality of fishes in Norris Lake. Jour. Tenn. Acad. Sci., 14: 239-260. Powers, J. H. 1905. New forms of Volvox. Trans. Amer. Microsc. Soca: 123-149; Pls. 11-14. Prescott, G. W. 1927. The motile algae of Iowa. Univ. Iowa Studies Nat. Hist., 12: 1-40; Pls. 1-10. 1931. Iowa algae. Ibid., 13: 1-235, Pls. 1-89. 193la. Iowa lake survey. A report to the Iowa State Fish and Game Com- mission. Mimeographed. 1936. Notes on the algae of Gatun Lake, Panama Canal. Trans. Amer. Microsc. Soc., 55: 501-509; Pls. LXIV-LXV. 1937.* Preliminary notes on the desmids of Isle Royale, Michigan. Pap. Mich. Acad. Sci., Arts, and Letters, 22: 201-212; Pl. 19. 1938.* A new species and a new variety of the algal genus Vaucheria De Candolle with notes on the genus. Trans. Amer. Microsc. Soc., 57: 1-10; Pls. 1, 2. 1938a. Objectionable algae and their control in lakes and reservoirs. Municipal Rev., 1(No. 2/3) [reprint; pages not numbered]. 1938b.* Further notes on the desmids of Isle Royale, Michigan. The genus Cosmarium. Pap. Mich. Acad. Sci., Arts, and Letters, 23: 203-214. 1939.* Some relationships of phytoplankton to limnology and aquatic biology. In Problems of lake biology. Amer. Assoc. Ady. Sci., Publ. No. 10: 65-78; Figs. 2-4. 1940.* Desmids of Isle Royale, Michigan. The genera Staurastrum, Micrasterias, Xanthidium, and Euastrum, with a note on Spinoclosterium. Pap. Mich. Acad. Sci., Arts, and Letters, 25(1939): 89-100. 1941.* A concluding list of desmids from Isle Royale, Michigan. Ibid., 26(1940): 23-29; Pls. 1, 2. 1942. The fresh-water algae of southern United States. II. Trans. Amer. Microsc. Soc., 61: 109-119. 1944.* New species and varieties of Wisconsin algae. Farlowia, 1: 347-385. 1948. Objectionable algae with reference to the killing of fish and other animals. Hydrobiologia, 1(No. 1): 1-18. Prescott, G. W., and CroaspaLe, Hannan T. 1937. New or noteworthy fresh water algae of Massachusetts. Trans. Amer. Microse. Soc., 56: 269-— 282; Pls. 1-3. 1942. The algae of New England. II. Amer. Midl. Nat., 27: 662-676; Pls. 1-5. Prescott, G. W., and Macnorra, ANGELINA. 1935.* Notes on Michigan des- [ 644 ] mids with descriptions of some species new to science. Pap. Mich. Acad. Sci., Arts, and Letters, 20: 157-170. Prescott, G. W., Sizva, H., and Wane, W. E. 1949.* New or otherwise inter- esting fresh-water algae from North America. Hydrobiologia, 2(No. 1): 84-91; Pls. 1-2. PrincsHEIM, E. G. 1942. Contributions to our knowledge of saprophytic algae and flagellata. III. Astasia, Distigma, Menoidium and Rhabdomonas. New Phytol., 41: 171-205. PrincsHem, N. 1856. Untersuchungen ueber Befruchtung und Generations- wechsel der Algen. Monatsber. d. Konigl. Akad. d. Wiss. z. Berlin, 1856: 925-237; 1 pl. Figs. 1-10. 1858. Beitriige zur Morphologie und Systematik der Algen. Pringsh. Jahrb. Wiss. Bot., 1: 1-81; Pls. 1-6. 1860. Beitrage zur Morphologie und Systematik der Algen. III. Die Coleochaeteen. Ibid., 2. 1-38; Pls. 1-6. Printz, H. 1913. Eine systematische Uebersicht der Gattung Oocystis Nageli. Nyt Mag. f. Natur., 51: 165-203; Pls. 4-6. 1914. Kristianiatraktens Proto- coccoideer. Skr. Vidensk. i Kristiania. Mat.-Nat. KI., 1913(No. 6): 1-128; Pls. 1-7. 1915. Beitriige zur Kenntnis der Chlorophyceen und ihrer ver- breitung in Norwegen. Det. Kgl. Norske Vidensk. Selskabs Skrifter, 1915 (No. 2): 1-76. 1915a. Die Chlorophyceen des siidlichen Sibiriens und des Uriankailandes. Ibid., 1915 (No. 4): 1-52; Pls. 1-7. 1927.+ Chlorophyceae. In A. Engler and K. Prantl, Die Natiirlichen Pflanzenfamilien. 3: 1-463; Figs. 1-366. Leipzig. 1940.+ Vorarbeiten zu einer Monographie der Trentepohlia- ceen. Nyt Mag. f. Natur., 80: 137-210. Prircuarp, A. 1841. A history of infusoria, living and fossil. London. 1861. A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign. 4th ed. London. Pitter, A. 1909. Die Emahrung der Wassertiere und der Stoffhaushalt der Gewiasser. Jena. Rasennorst, L. 1847. Deutschlands Kryptogamen-Flora, oder Handbuch zur Bestimmung der kryptogamischen Gewiichse Deutschlands, der Schweiz, des Lombardisch-Venetianischen Kénigreichs und Istriens. H, No. 2. Algen. Leipzig. 1849-1860. Die Algen Sachsen’s. 1863. Kryptogamen-Flora von Sachsen, der Ober-Lausitz, Thiiringen und Nordbohmen, mit Beriicksi- chtigung der benachbarten Linder. Erste Abtheilung. Leipzig. 1864-1868. Florae Europaea algarum aquae dulcis et submarinae. 3 Vols. Leipzig. Raciworski, M. 1889. Przeglad Gatunké6w Rodzaju Pediastrum. Rozpr. i Sprawozd. Wydz. III, Akad. Umiej.'w. Krakowie, 20: 1-37. Ratrs, J. 1844. On the British Desmidieae. Ann. and Mag. Nat. Hist., 14(Ser. 1): 187-194, 256-261, 391-396, 465-471. 1848. The British Desmidieae. 266 pp.; Pls. 1-35. London. 1850. On the Nostochineae. Ann. and Mag. Nat. Hist., 5(Ser. 2): 321-343. Ranpnawa, M. S. 1936. Contributions to our knowledge of the freshwater algae of northern India. I. Oedogoniales. Proc. Indian Acad. Sci., 4: 97-107; Pls. 6-8. 1937. Genus Zygnemopsis in northern India. Ibid., 5: 297-314; Figs. 1-8. 1938. Observations on some Zygnemales from northern India. Parts LII. Ibid., 8: 109-150, 336-366; Figs. 1-58. 1939. Genus Vaucheria in northern India. Arch. f. Protist., 92: 537-542. Rao, C. B. 1936. The Myxophyceae of the United Provinces, India.—II. Proc. Indian Acad. Sci., 3: 165-174; Figs. 1-3. 1937. The Zygnemoideae of the United Provinces, India. I. Jour. Indian Bot. Soc., 16: 269-288. 1937a. The Myxophyceae of the United Provinces, India.—III. Proc. Indian Acad. Sci., 6: 339-375. 1938. The Zygnemoideae of the Central Provinces, India.—I. Jour. Indian Bot. Soc., 17: 341-853. [ 645 ] Rawson, D. S. 1930. The bottom fauna of Lake Simcoe and its réle in the ecology of the lake. Univ. Toronto Studies, Publ. Ontario Fish Res. Lab., No. 40. 1939. Some physical and chemical factors in the metabolism of lakes. In Problems of Lake Biology. Amer. Assoc. Adv. Sci., Publ. No. 10: 9-26. Raymonp, M. R. 1937.* A limnological study of the plankton of a concretion- forming marl lake. Trans. Amer. Microsc. Soc., 56: 405-430. Rayss, TscHarna. 1915. Le Coelastrum proboscideum Bohl. Etude de planc- tologie expérimentale suivi d’une revision des Coelastrum de la Suisse. Mater. pour la Flore Crypt. Suisse, 5: 1-65; Pls. 1-20. 1930. Microthamnion Kuetzingianum Naeg. Bull. Soc. Bot.-Geneve, 21(Sér. 2): 143-160; Figs. 1-9. Rew, C. B. 1939. The effect of stream conditions on lake plankton. Trans. Amer. Micros. Soc. 58: 398-403. ReEmnBOLD, D. T. 1890. Die Chlorophyceen (Griintange) der Kieler Fohrde. Schrif. des naturw. Vereins f. Schleswig-Holstein, 8( Heft 1): 109-144. RemnuaArp, E. G. 1931.* The plankton ecology of the upper Mississippi, Min- neapolis to Winona. Ecol. Monogr., 1: 395-464; Figs. 1-11. 1941. Notes on Aphanizomenon with a description of a new species. Amer. Jour. Bot., 28: 326-329. RetnHarpt, L. 1876. Entwickelungsgeschichte der Characien (rossice). Pro- toc. de Seckt der 5. Versamml. russ. Naturf. und Aerzte in Warschau. Warsaw. REINKE, J. 1879. Zwei parasitische Algen. Bot. Zeit., 37: 473-478. Rewscu, P. F. 1867. Die Algenflora des mittleren Theiles von Franken, ent- haltend die vom Autor bis jetzt in diesen Gebieten beobachteten Siisswasser- algen, etc. Abh. Naturh. Ges. Niimberg, 3(1866): 1-238; Pls. 1-3. (Also printed separately, Niirnberg, 1867.) 1875. Contributiones ad algologeam et tungologeam. Leipzig. 1878. Contributiones ad floram algarum aquae dulcis Promontorii Bonae Spei. Jour. Linn. Soc. Bot., 16: 232-248. 1879. Eine neues Genus der Chroolepideae. Bot. Zeit., 37: 361-366. 1887. Eine neue Vaucheria der Corniculatae, sowie tiber gynandrische Bildung bei Vaucheria. Ber. d. Deutsch Bot. Ges., 5: 189-192. 1888. Familiae Polyedriearum mono- graphia. Notarisia, 3: 493-516; Pls. 4-8. RENDLE, A. B., and West, W. 1899. A new British freshwater alga. Jour. Bot., 87: 289-291. Ricu, FLoreNnce. 1932. Contributions to our knowledge of the freshwater algae of Africa. 10. Phytoplankton from South Africa Pans and Vleis. Trans. Roy. Soc. S. Africa, 20(Pt. 2): 149-188. 1935. Contributions to our knowledge of the freshwater algae of Africa. 11. Algae from a Pan in Southern Rhodesia. Ibid., 23( Pt. 2): 107-160; Figs. 1-24. Ricu, FLoRENcCE, and Pocock, Mary A. 1933. Observations on the genus Volvox in Africa. Ann. S. African Mus., 16: 427-471. Ricuter, P. 1884. In Literaturdfversigt. Algae aquae dulcis exsiccatae prae- cipue scandinavicae quas adjectis chlorophyllaceis et phychromaceis dis- tribuerunt Veit Wittrock et Otto Nordstedt. Bot. Notiser, 1884: 121-128. 1894. Gloiotrichia echinulata P. Richt., eine Wasserblute des Grossen und Kleinen Pléner Sees. Forsch. Biol. Stat. z. Plén, 2: 31-47. 1896. Scenedesmus Opoliensis P. Richt. nov. sp. Zeit. f. Angw. Mikro., 1: 83-7. 1897. Siisswasser- algen aus dem Umanakdistrikt. Bibl. Bot., 8( Heft 42): 1-12. Rickett, H. W. 1921.* A quantitative study of the larger aquatic plants of Lake Mendota. Trans. Wis. Acad. Sci., Arts, and Letters, 20: 501-527. 1924.* A quantitative study of the larger aquatic plants of Green Lake, Wisconsin. Ibid., 21: 381-414; Figs. 1-7. Ritey, Gorpon A. 1939. Correlations in aquatic ecology, with an example of their applications to problems of plankton productivity. Jour Marine Res. 2: 56-73; Figs. 14-16. [ 646 | Ripart, J. 1876. Notice sur quelques espéces rares ou nouvelles de la flore cryptogamique de la France. Bull. Soc. Bot. France, 25: 158-168. Rosinson, Cuas. Bupp. 1906.+ The Chareae of North America. Doctoral thesis, Columbia University. New York, Rox, J. 1925. Les nouvelles espéces des algues trouvées aux environs de la station biologique du Donetz du Nord. (Russian with French summary. ) Arch. Russ. Protist., 4( No. 3/4): 187-152. 1926. Untersuchungen am Phyto- plankton der Binnengewdsser in Ukaja. Ibid., 5: 1-44. Rose, Eart T, 1934. Notes on the life history of Aphanizomenon flos-aquae. Univ. Iowa Studies Nat. Hist., 16: 129-136. RosENBERG, Marie. 1939. A discussion of freshwater biology and its appli- cations. III. Algal physiology and organic production. Ann. Appl. Biol., 26: 172-174. RostTAFINsKI, J. 1875. Quelques mots sur l’Haematococcus lacustris et sur les bases d’une classification naturelle’ des algues Chlorospordes. Mem. Soc. Nat. Cherbourg, 19: 137-154. RosTAaFINSKI, J., and Worontn, M. 1877. Ueber Botrydium granulatum. Leip- zig. Bot. Zeit., 35: 649-671; Pls. 7-11. Rotu, A. W. 1797. Bemerkungen iiber das Studium der kryptogamischen Was- sergewachse. Hannover. 1797-1806. Catalecta botanica, 1-3. Leipzig. 1800. Tentamen florae germanicae. Vol. 3. Leipzig. RoussE.ET, C. F. 1914. Remarks on two species of African Volvox. Jour. Que- kett Microsc. Soc., 12( Ser. 2): 3938-394. Sanpor, Lancer. 1934. A Spirogyrak. A Spirogyrak monografikus Feldolo- gozdsa, Kulénés Tekintettel Nagymagyaroszagra. Folia Crypt., 1: 1253-1304. SAUNDERS, DE ALTON. 1894. Protophyta-Phycophyta. Flora of Nebraska. Vol. L. Lincoln. Sawyer, C. N., Lackey, J. B., and Lenz, A. T. 1943.* Investigation of the odor nuisance occurring in the Madison Lakes particularly Lakes Monona, Waubesa and Kegonsa from July 1942 to July 1943. A mimeographed re- port to the Hon. S. Goodland, Acting Governor of Wisconsin. ScHAaRscHMipT-IstvanFFI, J. 1881. Specimen Phycologiae aequatoriensis. Mag- yar Novenytanu Lapok, 5: 17-24. ScHERFFEL, A. 1899. Phaeocystis globosa n. sp. Ber. d. Deusch. Bot. Ges., 17: 317-318. 1908. Asterococcus n. g. superbus (Cienk.) Scherffel und dessen angebliche Beziehungen zu Eremosphaera. Ibid., 26A: 762-771. 1908a. Einiges zur Kenntnis von Schizochlamys gelatinosa A. Br. Ibid.: 783-795. 1911. Beitrag zur Kenntnis der Chrysomonadineen. Archit. Proust.) 22: 299-344. ScHEwrAkorFr, W. 1893. Ueber die geographische Verbreitung der Siisswasser- Protozoén. Mém. Acad. Imper. Sci. St. Pétersb., 41(Ser. 7): 1-201. ScHiLLER, J. 1933-1937.+ Dinoflagellatae. In L. Rabenhorst, Kryptogamen- Flora von Deutschland, Oesterreich und der Schweiz. 10(1933), Teil 1: 1-617; Teil 2, Lf. 1(1935): 1-160; Lf. 2(1935): 161-320; Lf. 3(1937): 321-480; Lf. 4(1937): 481-590. Leipzig. Scumuine, A. J. 1891. Die Siisswasser-Peridineen. Flora Allgm. Bot. Zeit., 74: 220-299. 1913. Dinoflagellatae (Peridineae). In A. Pascher, Die Siisswasser- flora Deutschlands, Oesterreichs und der Schweiz. Heft 3: 1-66; Figs. 1-69. ena. ee cans L. 1925. Myxophycearum in provincia Charkoviensi ( Ukrainae ) inventarum novae species et varietates. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 2(No. 6): 87-89. ScuMarpa, L. K. 1850. Neue Formen von Infusorien. Denschr. Kais. Akad. Wiss. Wien, 1( Abt. 2): 9-14; Pls. 3, 4. 1854. Zur Naturgeschichte Aegyptens. Ibid., 7( Abt. 2): 1-28. ScumMiLE, W. 1893. Beitrige zur Algenflora des Schwarzwaldes und der Rheinebene. Ber. d. Natur. Ges. Freiburg, 7: 1-45 (68-112, double paging ) [ 647 J 1894. Aus der Chlorophyceen-Flora der Torfstiche zu Virnheim. Flora, 78: 42-66; Pl. 7. 1895. Weitere Beitrage zur Algenflora der Rheinebene und des Schwarzwaldes. Hedwigia, 34: 66-83. 1895a. Einige Algen aus Sumatra. Ibid., 34: 293-307; Pl. 4. 1897. Algen aus den Hochseen des Kaukasus. Rep. Bot. Gard. Tiflis, 2: 267-276. 1897a. Beitrage zur Algenflora des Schwarzwaldes und des Oberrheins. VI. Hedwigia, 36: 1-25. 1897b. Algolo- gishen Notizen. II. Conferva Sandvichense Ag. Allg. Bot. Zeitschr., 3: 3-4. 1897c. Algologische Notizen. V—VII. Ibid., 3: 107-108. 1898. Ueber einige von Prof. Lagerheim in Ecuador und Jamaika gesammelte Blattalgen. Hed- wigia, 37: 61-75. 1898a. Ueber einige von Knut Bohlin in Pite Lappmark und Vesterbotten gesammelte Siisswasseralgen. Bih. Kongl. Sv. Vet.-Akad. Handl., 24, Afd. 3, No. 8: 1-71. 1899. Vier neue Siisswasseralgen. Oesterr. Bot. Zeit., 1899(No. 1): 1-4. 1899a. Einige Algen aus preussischen Hochmooren. Hedwigia, 38: 156-176. 1900. Algologische Notizen. VHI-IX. Allgm. Bot. Zeitschr., 5(1899): 2-4. 1900a. Algologische Notizen. X—XIII. Ibid., 5: 17-20. 1900b. Ueber einige von Professor Hansgirg in Istindien gesammelte Siisswasseralgen. Hedwigia, 39: 160-190. 1900c. Einige von Dr. Holderer in Centralasien gesammelte Algen. Ibid., 39: [141-143]. 1900d. Ueber Plank- tonalgen und Flagellaten aus dem Nyassasee. Engler’s Bot. Jahrb., 27: 229-237; Pls. 1-3. 1900e. Beitrage zur Kenntniss der Planktonalgen. Ber. d. Deutsch. Bot. Ges., 18: 144-158. 1900f. Drei interessante tropische Algen. Bot. Centralbl., 81: 417-418. 1900g. Algen des Siisswassers. Ber. d. Deutsch. Bot. Ges., 18: [107-117]. 1901. Algologische Notizen. XV. Allg. Bot. Zeitschr., 6: 233-235. 190la. Ueber drei Algengenera. Ber. d. Deutsch. Bot. Ges., 19: 10-24. 1901b. In Beitrage zur Flora von Afrika XXII. Schizophyceae, Con- jugate, Chlorophyceae. Engler’s Bot. Jahrb., 30: 239-445. 1902. Notizen zu einigen Siisswasseralgen. Hedwigia, 41: 150-163. 1902a. In Hans Simmer, Vierter Bericht tiber die Kryptogamenflora der Kreuzeckgruppe in Karnten. Allg. Bot. Zeitschr., 7(1901): 41-43, 83-86. 1903. Algen, insbesondere solche des Plankton, aus dem Nyassa-See und seiner Umgebung gesammelt von Dr, Fiilleborn. Engler’s Bot. Jahrb., 32(1902): 56-88; Pls. 1-3. 1903a. Bemerkungen zu einigen Siisswasseralgen. Ber. d. Deutsch. Bot. Ges., 21: 346-855. Scumupt, J. 1899. Danmarks blaagrénne Alger (Cyanophyceae Daniae). Bot. Tidsskr., 22: 2838-419. Scuomer, H. A., and Jupay, C. 1935.* Photosynthesis of algae at different depths in some lakes of northeastern Wisconsin. I. Observations of 1933. Trans. Wis. Acad. Sci., Arts, and Letters, 29: 173-193. ScuHraMM, J. R. 1914. A contribution to our knowledge of the relation of certain species of grass-green algae to elementary nitrogen. Ann. Missouri Bot. Gard., 1: 157-184. ScurANk, F. von Pau. 1783. Botanische Rhapsodien. Der Naturforscher, 19: 116-128. 1793. Mikroskopische Wahrnehmungen. Ibid., 27: 26-87. ScHROEDER, B. 1897. Ueber das Plankton der Oder. Ber. d. Deutsch. Bot. Ges., 15: 482-492. 1897a. Die Algen der Versuchsteiche des Schles. Fischerei- vereins zu Trachenberg. Forsch. Biol. Stat. z. Plén, 5: 29-66. 1898. Neue Beitrage zur Kenntnis der Algen des Riesengebirges. Ibid., 6: 9-47; Pls. 1, 2. 1898a. Planktologische Mittheilungen. Biol. Centralbl., 18: 525-535. 1899. Das Plankton des Oderstromes. B. Das pflanzliche Plankton der Oder. Forsch. Biol. Stat. z. Plén, 7: 15-24. 1902. Untersuchungen iiber Gallert- bildung der Algen. Ver. Naturh. med. Vereins Heidelberg, 7: 139-196. Pls. 1, 2. 1920. Schwebepflanzen aus dem Saarbor-Seen und aus den grosseren Seen bei Liegnitz. Ber. d. Deutsch. Bot. Ges., 38: 122-135. [ 648 J Scuuette, H. A. 1918.* A biochemical study of the plankton of Lake Men- dota. Trans. Wis. Acad. Sci., Arts, and Letters, 19(Pt. 1): 594-613. ScHuETTE, H. A., and ALprer, H. 1929.* A note on the chemical composition of Chara from Green Lake, Wisconsin. Trans. Wis. Acad. Sci., Arts, and Letters, 24: 141-145. ScCHUETTE, H. A., and HorrMan, A.ice E. 1921.* Notes on the chemical composition of some of the larger aquatic plants of Lake Mendota. I. Clado- phora and Myriophyllum. Trans. Wis. Acad. Sci., Arts, and Letters, 20: 529-531. Scuuuze, B. 1927. Zur Kenntnis einiger Volvocales. Arch. f. Protist., 58: 508-576. Scuutt, F. 1896. Peridiniales. In A. Engler and K. Prantl, Die natiirlichen Pflanzenfamilien. Teil 1, Abt. 1. Leipzig. SecxT, H. 1922. Estudios hidrobiologicos en la Argentina—Flagellatae. Bol. Acad. Nac. Cienc. Cordoba, 25: 430-490. 1938. Contribucién al conocimiento de las algas aerofilas en la Argentina. Ibid., 34: 108-141. Sexico, A. 1887. Untersuchungen iiber Flagellaten. Beitr. Biol. Pflanzen, 4: 145-180; P1.8. SENN, G. 1899. Ueber einige coloniebildende einzellige Algen. Bot. Zeitg., 57: 39-104; Pls. 2-3. 1900. Flagellata. In A. Engler and K. Prantl, Die Natiir- lichen Pflanzenfamilien. Teil 1, Abt. 2: 93-192; Figs. 63-140. Leipzig. SETCHELL, Wo. A. 1895. Notes on some Cyanophyceae of New England. Bull. Torr. Bot. Club, 22: 424-431. 1896. Notes on Cyanophyceae. I. Erythea, 4: 87-89. 1896a.* Notes on Cyanophyceae. II. Ibid., 4: 189-194. SETCHELL, Wm. A., and Garpner, N. L. 1903.+ Algae of Northwestern America. Univ. Calif. Publ. Bot., 1: 165-418; Pls. 17-27. SEVILLE-KENT, W. 1880-1882. A manual of the Infusoria. London. SHaw, W. R. 1894. Pleodorina, a new genus of the Volvocineae. Bot. Gaz., 19: 279-288; Pl. 27. Simmer, Hans. 1898. Erster Bericht iiber die Kryptogamenflora der Kreu- zeckgruppe in Karnthen. Allg. Bot. Zeitschr., 4: 74-78; 99-100; 118-120; 141-144; 158-159. 1901. Vierter Bericht iiber die Kryptogamen-flora der Kreuzeckgruppe in Karnten. [bid., 7: 41-48, 83-86. Sincu, R. N. 1938. The Oedogoniales of the United Provinces, India. Proc. Indian Acad. Sci., 8: 373-395. Stropot, S. 1884.+ Les Batrachospermes. Organisation, fonctions, développe- ment, classification. Paris. Sxuja, H. 1926. Zwei neue Zygnemaceen mit blauem Mesospor. Acta Horti Bot. Univ. Latviensis, 1: 109-114; 1 pl. 1926a. Vorarbeiten zu einer Algen- flora von Lettland. I. Ibid., 1: 33-54. 1926b. Vorarbeiten zu einer Algenflora von Lettland. II. Ibid., 1: 149-178. 1927. Vorarbeiten zu einer Algenflora von Lettland. HI. Ibid., 2: 51-116. 1928. Vorarbeiten zu einer Algenflora von Lettland. IV. Ibid., 3: 103-218; Pls. 14. 1930. Siisswasseralgen von den westestnische Inseln Saaremaa und Hiiumaa. Ibid., 4(1929): 1-74. 1931. Untersuchungen iiber die Rhodophyceen des Siisswassers. Arch. f. Protist., 74: 297-308. 1934. Beitrag zur Algenflora Lettlands I. Acta Horti Bot. Univ. Latviensis, 7(1932): 25-86. 1935. Die Flechte Coenogonium nigrum (Huds.) Zahlbr. und ihre Gonidie. Ibid., 8: 21-44. 1937. Siisswas- seralgen aus Griechenland und Kleinasien gesammelt von Prof. C. Regel. Hedwigia, 77: 15-70; Pls. 1-3. 1938. Die Siisswasserrhodophyceen der Deutschen Limnologischen Sunda-Expedition. Arch. f. Hydrobiol. (Suppl. ) 15: 603-637; Pls. 29-35. 1939. Beitrag zur Algenflora Lettlands. II. Acta Horti Bot. Univ. Latviensis, 11/12: 41-169. 1939a. Versuch einer systema- tischen Einteilung der Bangioideen oder Protoflorideen. Ibid., 11/12: 23-40. [ 649 ] 1948. Taxonomie des Phytoplanktons einiger Seen in Uppland, Schweden. Symbol. Bot. Upsal., 9(No. 3): 1-399; Pls. 1-39. Sxvortzow, B. W. 1917. Ueber Flagellata aus Mandschurei. Zhurnal Mikrobiol. (Petrograd), 4(No. 1/2): 55-77. 1919. Notes on the agriculture, botany and the zoology of China. XXXI. On new flagellata from Manchuria. Jour. N. China Branch Roy. Asiatic Soc., 50: 96-104. 1922. On the winter phyto- plankton of the fishponds of Foochow. Ibid., 53: 190-195. 1925. Die Euglenaceengattung Trachelomonas Ehrenberg. Eine systematische Ueber- sicht. Sungari Station zu Harbin der Ges. z. erforschung der Mandschurei, 1(No. 2): 1-101; Pls. 1-8. 1925a. Ueber einige Siisswasseralgen Umgegend von Peking (China). Arch. f. Hydrobiol. u. Planktonk., 16: 337-340. 1925b. Zur Kenntnis der Mandschurischen Flagellaten. Beih. Bot. Centralbl., 41 (Abt. 2): 811-315. 1925c. Ueber neue und wenig bekannte Formen der Euglenaceengattung Trachelomonas Ehrenberg. Ber. d. Deutsch. Bot. Ges., 43: 306-315. 1926. Ueber einige Siisswasseralgen aus der Nord-Mandschurei, im Jahre 1916 gesammelt. Arch. f. Hydrobiol. u. Planktonk., 16(Heft 3): 421-436; Figs. 1-8. 1927. Ueber neue und wenig bekannte Formen der Euglenaceengattung Trachelomonas Ehrenb. II. Ber. d. Deutsch. Bot. Ges., 44: 603-621. 1928. Die Euglenaceengattung Phacus Dujardin. Ibid., 46: 105-125; Pl. 2. 1929. Einige neue und wenig bekannte Chlamydomonadaceae aus Manchuria. Arch. f, Protist., 66: 160-163. Smitu, Gitpert M. 1913.* Tetradesmus, a new four-celled coenobic alga. Bull. Torr. Bot. Club, 40: 75-87; Pl. 1. 1914.* The organization of the colony of certain four-celled coenobic algae. Trans. Wis. Acad. Sci., Arts, and Letters, 17 (Pt. If): 1165-1220; Pls. 85-91. 1916.* New or interesting algae from the lakes of Wisconsin. Bull. Torr. Bot. Club, 43: 471-488; Pls. 24-26. 1916a.*+ A monograph of the algal genus Scenedesmus, based upon pure culture studies. Trans. Wis. Acad. Sci., Arts, and Letters, 18: 422-539; Pls. 25-33. 1916b.* A preliminary list of the algae found in Wisconsin lakes. Ibid., 18(Pt. IL): 531-565. 1917.* The vertical distribution of Volvox in the plankton of Lake Monona. Amer. Jour. Bot., 5: 178-185. 1918.7 A second list of algae found in Wisconsin lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 19: 614-654; Pls. 10-15. 1920.*+ Phytoplankton of the inland lakes of Wisconsin. Part. 1. Wis. Geol. and Nat. Hist. Surv., Bull. 57: 1-243; Pls. 1-51. 1922. The phytoplankton of the Muskoka region, Ontario, Canada. Trans. Wis. Acad. Sci., Arts, and Letters, 20: 323-364; Pls. 8-13. 1922a. The phytoplankton of some artificial pools near Stockholm. Arkiv f. Bot., 17(No, 13): 1-8; Figs. 1-28. 1924. Ecology of the plankton algae in Palisades Interstate Park, including the relation of control methods to fish culture. Roosevelt Wild Life Bull., 2: 95-195; Pls. 3-24. 1924a.*+ Phyto- plankton of the inland lakes of Wisconsin. II. Wis. Geol. and Nat. Hist. Surv., Bull. 57: 1-227; Pls. 52-88. Madison. 1926. The plankton algae of the Okoboji region. Trans. Amer. Microsc. Soc., 45: 156-233; Pls. 1-20. 1930. Notes on the Volvocales. I-IV. Bull. Torr. Bot. Club, 57: 359-370; Pls. 17,18. 1931. A consideration of the species of Eudorina. Ibid., 57: 359-364; Pl. 17. 1933.*+ Freshwater algae of the United States. 716 pp.; Figs. 1449. New York. 1937. Cryptogamic Botany. Vol. I. 545 pp.; Figs. 1-292. New York. 1944.* A Comparative study of the species of Volvox. Trans. Amer. Microsc. Soc., 63: 265-310; Figs. 1-46. Smitu, Girpert M., and Kiyver, F. D. 1929. Draparnaldiopsis, a new member of the algal family Chaetophoraceae, Trans. Amer. Microsc. Soc., 48: 196- 208; Pl. 25; Fig. 1. Smitu, J. E. 1790. English Botany, or coloured figures of British plants. London. Smitu, L. L. 1941.* A limnological investigation of a permanently stratified [ 650 ] lake in the Huron Mountain region of Michigan. Pap. Mich. Acad. Sci., Arts, and Letters, 26 (1940): 281-296. Snow, Jura. 1899.* Ulvella Americana. Bot. Gaz., 27: 309-314; Pl. 7. 1899a.* Pseudopleurococcus, nov. gen. Ann. Bot., 13: 189-195; Pl. 11. 1903. The plankton algae of Lake Erie, with special reference to the Chlorophyceae. Bull. U. S. Fish. Comm., 1902: 369-394. 1911. Two epiphytic algae. Bot. Gaz., 51: 360-368; Pl. 18. SOMMERFELDT, S. G. 1824. Physisk-Oeconomisk Beskrivelse over Saltdalen i Nordlandene. Det. Kgl. Norske Vid. Selsk-Skr. i det., 19th Aarh, 2: 1-148. STEIN, F. R. von. 1862. Der Organismus der Infusionsthiere. II, Abteilung; Naturgeschichte der heterotrichen Infusorien. Leipzig. 1878. Der Organ- ismus der Flagellaten nach einigen Forschungen in systematischer Reinen- folge bearbeitet. Der Organismus der Infusionstiere. III Abteilung. I Hifte. Die Naturgeschichte der Flagellaten oder Geisselinfusorien. Den noch nicht abgeschlossenen allgemeinen Teil nebst Erklarung der somtlichen Abbildun- gen enthaltend. 154 pp. Leipzig. 1883. Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reinenfolge bearbeitet. III Abteilung. II Hialfte. Die Naturgeschichte der Arthrodelen Flagellaten. 30 pp. Leipzig. SticknEY, M. E. 1909.* Notes on Spondylomorum quaternarium Ehrenb. Bull. Sci. Lab. Denison Univ., 14: 233-238; Pl. 6. STIZENBERGER, Ernst. 1852. Spirulina und Arthrospira nov. gen. Hedwigia, 1: 32-34. StockmayeER, S. 1890. Ueber die Algengattung Rhizoclonium. Ver. K. K. Zool.- Bot. Ges. Wien, 40: 571-586. Sroxes, A. C. 1885. Notes on some apparently undescribed forms of fresh- water infusoria. No. 2. Amer. Jour. Sci., 29(Ser. 3): 313-328; Pl. 3. 1885a. Notices of new fresh-water infusoria. IV. Amer. Monthly Microsc. Jour., 6: 183-190. 1886. Notes on Peridinium and other infusoria. Jour. Trenton Nat. Hist. Soc., 1(No. 1): 18-22. 1886a. Notices of new fresh-water infusoria. Proc. Amer. Philos. Soc., 23: 562-568; 1 pl. 1886b. Notices of new fresh- water infusoria. V. Amer. Monthly Microsc. Jour., 7: 81-86; Figs. 1-18. 1887. Notices of new fresh-water infusoria. VI. Ibid., 8: 141-147. 1888. A preliminary contribution toward a history of the freshwater infusoria of the United States. Jour. Trenton Nat. Hist. Soc., 1(No. 3): 71-819; Pls. 1-13. 1890. Notices of new fresh-water infusoria. Proc. Amer. Philos. Soc., 28: 74-80; 1 pl. 1894. Notices of presumably undescribed infusoria. Ibid., 33: 838-344. STRASBURGER, E. 1884. Das botanische Practicum. Jena. STRICKLAND, J. C. 1940. The Oscillatoriaceae of Virginia. Amer. Jour. Bot., 27: 628-633; Fig. 1. StrOM, K. Munster. 1921. The phytoplankton of some Norwegian Lakes. Videns. Skrift. I. Mat.-Nat. K]., 1921(No. 4): 1-51; Pls. 1-3. 1926. Norwe- gian mountain algae. Det. Norske Vid.-Akad. Oslo. I. Mat.-Nat. Kl. 1926 (No. 6): 1-263; 25 pls. 1928. Production biology of temperate lakes. Inter. Rev. Ges. Hydrobiol. u. Hydrogr., 19: 329-348. SuRBER, EucENE W. 1929. The utilization of sloughs in the Upper Mississippi Wild Life and Fish Refuge as fish ponds. Trans. Amer. Fish. Soc., 59: 106-1138. Swincte, W. T. 1894.* Cephaleuros mycoidea and Phyllosiphon, two species of parasitic algae new to North America. Proc. Amer. Assoc. Adv. Sci., 42: 260. Swirenxo, D. O. 1914. Zur Kenntnis der russischen Algenflora. I. Die Eug- lenaceengattung Trachelomonas. Arch. f. Hydrobiol. u. Planktonk., 9: 630- [ 651 } 647, 1915. Materialy k florie vodoroslei Rossii. Niepotoryia dannyia k sis- tematikie i geografii Euglenaceae. Obschchestvo Ispytatelei Prirody, Khar’kov. Trudy, 48(No. 1): 67-148. 1915a. Zur Kenntnis der russischen Algenflora. II. Euglenaceae (excl. Trachelomonas). Arch. f. Hydrobiol. u. Planktonk., 10: 321-339, 1928. Contributions a l'étude algologique de l'Ingoule. (Russian with French summary.) Arch. Russ. Protist., 7: 75-130 Tart, C. E. 1935. The Oedogoniaceae of Oklahoma including new species and varieties. Bull. Torr. Bot. Club, 62: 281-290; Pls. 15, 16. 1937. A new species of Vaucheria. Ibid., 64: 557; 1 fig. 1939.* Additions to the algae of Mich- igan. Ibid., 66: 77-85; Figs. 1-12. 1942. Additions to the algae of the west end of Lake Erie. Ohio Jour. Sci., 42: 251-256; Pls. 1,2. 1946. Some Oedogoniaceae and Zygnemataceae from Texas and Louisiana. Trans. Amer. Microsc. Soc., 65: 18-26; 1 pl. 1949.* New, rare, or otherwise interesting algae. Trans. Amer. Microsc. Soc., 68: 208-216, Pls. 1, 2. TANNER-FULLMAN, M. 1906. Sur un nouvel organisme du plancton du Schoen- enbodensee le Raphidium Chodati Tanner. Bull. Herb. Boiss., 6(Ser. 2): 156-158. TayLor, WM. RANpotpH. 1922. Notes on some algae from British Columbia. Rhodora, 24: 101-111. 1924. Further notes on British Columbia algae. Ibid., 26: 160-166. 1928. Alpine algal flora of the mountains of British Columbia. Ecology, 9: 343-348. 1932. Notes on the genus Anabaenopsis. Amer. Jour. Bot., 19: 454-463; Pls. 39,40. 1933. Methods for collection and study of fresh-water algae. Jour. Mich. Schoolmasters Club, 1933: 114-125. 1935. Alpine algae from the Santa Marta Mountains, Colombia. Amer. Jour. Bot., 22: 763-781; Pls. 1-3. 1935a.* Phytoplankton of Isle Royale. Trans. Amer. Microsc. Soc., 54: 83-97; Pls. 14-17. 1937.+ Marine algae of the northeastern coast of North America. 427 pp.; Pls. 1-60. Ann Arbor. Taytor, WM. Ranpotpn, and Corton, H. S. 1928. The phytoplankton of some Arizona pools and lakes. Amer. Jour. Bot., 15: 596-614; Pls. 46, 47. Temtinc, E. 1912. Schwedische Planktonalgen. I., Phytoplankton aus dem Rastasj6n bei Stockholm. Svensk Bot. Tidskr., 6: 266-281. 1916. Ibid., I. Tetrallantos, eine neue Gattung der Protococcoideen. Ibid., 10: 59-66; F igs. 1-15. 1941. Aeruginosa oder flos-aquae, eine Kleine Microcystis-studie. Ibid., 35(No. 4): 337-349; Figs. 1-12. 1946. Zur Phytoplanktonflora Schwedens. Bot. Notiser, 1946: 61-88; Figs. 1-22. TemMPeERLy, B. N. 1936. The boghead controversy and the morphology of the boghead algae. Trans. Roy. Soc. Edinburgh, 58(Pt. 3): 855-868. TrEoporesco, E. C. 1907. Matériaux pour la flore algologique de la Roumaine. Beih. Bot. Centralbl., 21(No. 2): 103-219. THIENEMANN, Aucust. 1935. Die Bedeutung der Limnologie fiir die Kultur der Gegenwart. Stuttgart. Tompson, H. D. 1896.* Report on the plants. Appendix I. In A biological examination of Lake Michigan in the Traverse Bay region. Bull. Mich. Fish. Comms, 63) 3=93) Elssl=3: THompson, R. H. 1938. A preliminary survey of the freshwater algae of eastern Kansas. Univ. Kansas Sci. Bull., 25: 5-83; Pls. 1-12. 1938a. Coronastrum, a new genus of algae in the family Scenedesmaceae. Amer. Jour. Bot., 25: 692-694; Figs. 1-10. 1947. Fresh-water Dinoflagellates of Maryland. State Md. Bd. Nat. Resources, Publ. No. 67: 3-24; Pls. 1-4. 1949. Immobile Dinophyceae. I. New records and a new species. Amer. Jour. Bot., 36 (No. 3): 301-308; Figs. 1-34. THuNMARK, S. 1945. Die Abwasserfrage der Vaxjoseen in hydrobiologische Beleuchtung. Medd. f. Lunds Univ. Limnol. Inst., No. 4: 1-239; Figs. 146. Tuuret, G. 1850. Recherches sur les zoospores des algues et les anthéridies [ 652 } des cryptogames. Ann. Sci. Nat. Bot., 14(Sér. 3): 214-260; Pls. 16-81. 1875. Essai de classification des Nostochinées. Ibid., 1(Sér. 6): 372-382. 1885. In Hauck, F. 1885. Des Meeresalgen Deutschlands und Oesterreichs. Raben- horst’s Kryptogamen-Flora. 2. Leipzig. 1887. In E. Bornet and Ch. Flahault, Revision des Nostocacées. Ann. Sci. Nat. Bot., 5(Sér. 7): 51-129. Tuuret, G., and Bornet, E. 1878. Etudes phycologiques. Paris. Tirrany, L. H. 1921. New forms of Oedogonium. Ohio Jour. Sci., 21: 272-274. 1921a. Algal food of the young gizzard shad. Ibid., 21: 113-122. 1924. Some new forms of Spirogyra and Oedogonium. Ibid., 24: 180-190; Pls. 1-3. 1926. The filamentous algae of northwestern Iowa, with special reference to the Oedogoniaceae. Trans. Amer. Microsc. Soc., 45: 69-132; Pls. 1-16. 1926a. The algal collection of a single fish. Pap. Mich. Acad. Sci., Arts, and Letters, 6: 303-306. 1927. New species and varieties of Chlorophyceae. Bot. Gaz., 83: 202-206; Pl. 9. 1928. The algal genus Bulbochaete. Trans. Amer. Mi- crosc. Soc., 47: 121-177; Pls. 14-23. 1929. A key to the species, varieties, and forms of the algal genus Oedogonium. Ohio Jour. Sci., 29: 62-80. 1930.t* The Oedogoniaceae, a monograph. 188 pp.; 64 pls. Columbus, Ohio. 1934.+* The Oedogoniaceae. Supplementary paper number one. Ohio Jour. Sci., 34: 323-326. 1934a. The plankton algae of the west end of Lake Erie. Ohio State Univ., Franz Theodore Stone Lab., Contrib. No. 6. 112 pp.; Figs. 1-374. 1936. Wille’s collection of Puerto Rican fresh-water algae. Brittonia, 2: 165-176; Pls. 1-3. 1936a. New species of Oedogonium. Trans. Amer. Microsc. Soc., 55: 1-5; Pl. 1. 1937.+ Oedogoniales. Oedogoniaceae. N. Amer. Flora, 11, Part 1. 102 pp. New York Bot. Gard. 1937a. The filamentous algae of the west end of Lake Erie. Amer. Mid]. Nat., 18: 911-951; Pls. 1-9. 1937b. Brazilian Oedogoniales. Rev. Sudamer. Bot., Montevideo, 4: 5—14; Figs. 1-6. 1938. Algae: the grass of many waters. Springfield, Ill. Tirrany, L. H., and Antsrrom, E. H. 1931. New and interesting plankton algae from Lake Erie. Ohio Jour. Sci., 31: 455-467; Pls. 1-3. Turrany, L. H., and Brirron, M. E. 1944. Freshwater Chlorophyceae and Xanthophyceae from Puerto Rico. Ohio Jour. Sci., 44: 39-50. Trrrany, L. H., and Transeau, E. N. 1927. Oedogonium periodicity in the north central states. Trans. Amer. Microsc. Soc., 46: 166-174; Figs. 1-3. TitpeN, JoserHine E. 1895. List of freshwater algae collected in Minnesota during 1884. Minn. Bot. Studies, 1(No. 20): 228-237. 1898. List of fresh- water algae collected in Minnesota during 1896 and 1897. Ibid., 2( No. 3): 25-29. 1910.* Minnesota algae. I. 328 pp.; Pls. 1-20. Minneapolis. 1935. The algae and their life relations. 550 pp.; Figs. 1-257. Minneapolis. TrmBerLake, H. G. 1902.* Development and structure of the swarmspores of Hydrodictyon. Trans. Wis. Acad. Sci., Arts, and Letters, 13: 486-522. TransEau, E. N. 1913. The periodicity of algae in Illinois. Trans. Amer. Microsc. Soc., 32: 31-40; Figs. 1-8. 1913a. Annotated list of algae of eastern Illinois. Trans. Ill. Acad. Sci., 6: 69-89. 1913b. The life history of Gloeo- taenium. Bot. Gaz., 55: 66-73; Pl. 3. 1914. New species of green algae. Amer. Jour. Bot., 1: 289-301; Pls. 25-29. 1915.* Notes on the Zygnemales. Ohio Jour. Sci., 16: 17-31. 1916. The periodicity of freshwater algae. Amer. Jour. Bot., 3: 121-133; Figs. 1-3. 1917.* The algae of Michigan. Ohio Jour. Sci., 17: 217-232. 1925.t* The genus Debarya. Ibid., 25: 193-199; Pls. 1, 2. 1926.+* The genus Mougeotia. Ibid., 26: 311-351; Pls. 1-7. 1933.+* The genus Zygogonium. Ibid., 33: 156-162; Pls. 1, 2. 1934.+* The genera of the Zygnemataceae. Trans. Amer. Microsc. Soc., 53: 201-207. 1934a. Notes on the Zygnemataceae. Ohio Jour. Sci., 34: 420. 1938. Notes on Zygnemataceae. Amer. Jour. Bot., 25(7): 524-528; Figs. 1-19. 1943. Two new Ulotrichales. [ 653 ] Qhio Jour. Sci., 43: 212-213. 1944. Notes on Zygnemataceae. Ibid., 44: 243-244, TransEau, E. N., and Tirrany, L. H. 1919. New Oedogoniaceae. Ohio Jour. Sci., 19: 240-243. TransEau, E. N., Tirrany, L. H., Tart, C. E., and Li, L. C. 1934.* New species of Zygnemataceae. Trans. Amer. Microsc. Soc., 53: 208-230; Pls. 17-21. TRELEASE, W. 1889.* The “working” of the Madison Lakes. Trans. Wis. Acad. Sci., Arts, and Letters, 7: 121-129. TressLer, W. L. 1939. The zooplankton in relation to the metabolism of lakes. In Problems of Lake Biology. Amer. Assoc. Adv. Sci., Publ. No. 10: 79-93. TressLeR, W. L., and Domoca.xa, B. P. 1931.* Limnological studies of Lake Wingra. Trans. Wis. Acad. Sci., Arts, and Letters, 26: 331-351. TressLer, W. L., Tirrany, L. H., and Spencer, W. P. 1940. Limnological studies of Buckeye Lake, Ohio. Ohio Jour. Sci., 40: 261-290. Troirzkaya, O. V. 1922. De Carteriis nonnullis minus cognitis notulae. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 1(No. 8): 114-119. 1922a. De varietate nova Anabaena Scheremetievi Elenk. Ibid., 1( No. 5): 77-78. 1928. Chlamydomonas sphaerica Troitzk. nov. sp. Ibid., 2(No. 6): 81-82. 19238a. De affinitate inter Coelosphaerium Nag. et Gomphosphaerium Kitz. Ibid., 2(No. 5): 69-78. Turner, W. B. 1893. Algae aquae dulcis Indiae orientalis. Kongl. Sv.-Vet. Handl., 25( No. 5): 1-187; Pls. 1-23. Turpin, P. J. 827. Dictionnaire des Sciences Naturelles. Vol. 50. ed. F. G. Levrault. 1828. Apercu organographique sur le nombre deux. Mém. Mus. d Hist. Nat. par les Prof. de cet establissement, 16: 296-344. Uncer, FRANz. 1854. Beitrage zur Kenntniss der niedersten Algenformen, nebst Versuchen ihre Entstehung betreffend. Denskr. Akad. Wiss. Wien, 7: 185-196. Unctr, W. B. 1941. A new variety of Trachelomonas urceolata (Protozoa, Mastigophora). Bull. Mt. Desert Isl. Biol. Lab., 1941: 15-17. 1941a, A preliminary survey of the protozoa of Beaver Lake near Salsbury Cove, Maine. Ibid., 1941: 17-18. Vaucuer, J. P. 1803. Histoire des confervés d’eau douce. Geneva. VELAsQuEZ, Grecoria T. 1939. On the viability of algae obtained from the digestive tract of the gizzard shad, Dorosoma cepedianum (Le Sueur). Amer. Mid]. Nat., 22: 376-412; Pls. 1-7. 1940.* A list of the filamentous Myxophyceae from Michigan. Ibid., 23: 178-181. Virieux, J. 1916. Recherches sur le plancton des lacs du Jura central. Ann. Biol. Lacustre, 8: 5-192; Figs. 1-46. ViscHER, W. 1920. Sur le polymorphisme de L’Ankistrodesmus Braunii (Nae- geli) Collins. Zeit. f£. Hydrol., 1: 5-50. Waern, M. 1938. Om Cladophora aegagropila, Nostoc pruniforme och andra alger i Lilla Ullevifjirden, Malaren. Bot. Notiser, 1938: 128-142. Wautstept, L. J. 1875. Monografi dfver Sveriges och Norges Characeer. Christiania. Waues, C. H. 1928. Dinoflagellates and Protozoa from British Columbia with descriptions of new species. Mus. and Art Notes (Vancouver, B. C.), 3: 1-8. 1929. Alpine Rhizopoda and Peridiniidae from British Columbia. Ann. Protist., Paris, 2: 179-183. WaxsMAN, SELMAN A. 1941. Aquatic bacteria in relation to the cycle of organic matter in lakes. In A Symposium on Hydrobiology. Madison. Wa.uicu, G. C. 1877. Observations on the Coccosphere. Ann. and Mag. Nat. Hist., 19( Ser. 4): 342-349. [| 654 J Wattrotu, F. W. 1815. Annus botanicus, sive supplementum tertium ad Curtii Sprengelii floram Halensem. Halle. 1833. Flora cryptogamica germanicae. Pars posterior. Niirnberg. 1833a. Compendium florae germanicae. IV. Niirnberg. Watton, L. B. 1915.+ A review of the described species of the order Eug- lenoidina Bloch. Ohio State Univ. Bull., 19: 343-459; Pls. 12-26; Fig. 1. 1930. Studies concerning organisms occurring in water supplies with parti- cular reference to those found in Ohio. Part. I. Ohio Biol. Surv. Bull. 5(No. 24): 1-86. Waiz, J. 1866.+ Beitrag zur Morphologie und Systematik der Gattung Vau- cheria DC. Jahrb. Wiss. Bot., 5: 127-160; Pls. 12-14. Warp, H. B., and Wuirrte, G. C. 1918. Freshwater biology. 1111 pp.; Figs. 1-1547. New York. Warminc, E. 1876. Om en Fircellet Gonium (Dujardins Tetramonas socialis). Bot. Tids., 9(Ser. 3): 69-83. WarTMANN, B., and ScHEenx, B. 1862. Schweizerische Kryptogamen. Exsic- cate. Fasc. I. St. Gallen. Watson, J. B., and TiLpEN, JosEPHINE E. 1930. The algal genus Schizomeris and the occurrence of Schizomeris Leibleinii Kiitzing in Minnesota. Trans. Amer. Microsc. Soc., 49: 160-167. Weser, Rotanp. 1933. Beitrige zur Kenntnis der Gattung Calothrix. Arch. £ Protist., 79: 391-415. We cu, Pau S. 1935. Limnology. New York. 1936.* Limnological investiga- tion of a strongly basic bog lake surrounded by an extensive acid-forming bog mat. Pap. Mich. Acad. Sci., Arts, and Letters, 21: 727-751. 1986a.* A limnological study of a small Sphagnum-leather leaf—black spruce bog lake with special reference to its plankton, Trans. Amer. Microsc. Soc., 55: 800- 312. 1938.+ A limnological study of a bog lake which has never developed a marginal mat. Ibid., 57: 344-357. 1941. Dissolved oxygen in relation to lake types. In A Symposium on Hydrobiology. Madison. Wesensurc-Lunp, G. 1908. Plankton investigations of the Danish lakes. General Part. The Baltic fresh-water plankton, its origin and variation. Copenhagen. West, G. S. 1899. The alga-flora of Cambridgeshire. Jour. Bot., 87: 49-58, 106-116, 216-225, 262-268, 291-299. 1902. On some algae from hot springs. Ibid., 40: 241-248; Pl. 439. 1904. A treatise on the British freshwater algae. 372 pp.; Figs. 1-166. Cambridge. 1904a. West Indian freshwater algae. Jour. Bot., 42: 281-294; Pl. 464. 1905. A comparative study of the dominant phanerogamic and higher cryptogamic flora of aquatic habit in three lake areas of Scotland. Proc. Roy. Soc. Edinburgh, 25(No. 11): 976-1023. 1907. Report on the freshwater algae, including phytoplankton, of the Third Tan- ganyika Expedition conducted by Dr. W. A. Cunnington, 1904-1905. Jour. Linn. Soc. Bot., 38: 81-197; Pls. 1-8. 1908. Some critical green algae. Ibid., 38: 279-289; Pls. 20,21. 1909. A biological investigation of the Peridineae of Sutton Park, Warwickshire. New Phytol., 8: 181-196. 1909a. The algae of the Yan Yean Reservoir, Victoria; a biological and ecological study. Jour. Linn. Soc. Bot., 39: 1-88; Pls. 1-6; Figs. 1-10. 1912. Algological notes.— X-XIII. Jour. Bot., 50; 321-331. 1914. A contribution to our knowledge of the freshwater algae of Columbia. Mém. Soc. Neuchat. Sci. Nat., 5: 1013- 1051. 1915. Algological Notes XIV-XVII. Jour. Bot., 53: 73-84. 1916.+ Algae. Vol. I. Myxophyceae, Peridineae, Bacillariaceae, Chlorophyceae, to- gether with a brief summary of the occurrence and distribution of fresh- water algae. 475 pp.; Figs. 1-271. Cambridge. [ 655 ] West, G. S., and Frirscu, F. E. 1927.+ A treatise on the British fresh-water algae. 534 pp.; Figs. 1-207. Cambridge. West, W. 1891. Notes on Danish algae. Nuova Notarisia, 1891: 418-425. 1892. Algae of the English lake district. Jour. Roy. Microsc. Soc. London, 1892: 713-748; Pls. 9-10. West, W., and West, G. S. 1894. New British freshwater algae. Jour. Roy. Microsc. Soc. London, 1894: 1-17. 1895. A contribution to our knowledge of the freshwater algae of Madagascar. Trans. Linn. Soc. Bot., 5(Ser. 2): 41-90. 1895a. New American algae. Jour. Bot., 33: 52. 1895b. On some fresh- water algae from the West Indies. Jour. Linn. Soc. Bot., 30(1893-1895): 264-280. 1896. On some new and interesting fresh-water algae. Jour. Roy. Microsc. Soc. London, 1896: 149-165. 1896a. Algae from Central Africa. Jour. Bot., 34: 377-384. 1897, Welwitch’s African freshwater algae. Ibid., 85: 1-7, 338-42, 77-89, 118-122, 172-188, 285-243, 264-272, 297-304. 1897a. A contribution to the freshwater algae of the south of England. Jour. Roy. Microsc. Soc. London, 1897: 467-511. 1898. Notes on freshwater algae of the West Indies. Jour. Linn. Soc. Bot., 34: 279-295. 1900. Notes on freshwater algae. II. Jour. Bot., 38: 289-299. 1900-1901. The alga-flora of Yorkshire; a complete account of the known fresh-water algae of the county. Bot. Trans. York. Nat. Union, 5, Pt. 22: 5-22; Pt. 23: 53-100; Pt. 25(1901): 101-164; Pt. 27(1901): 165-239. 1901. Fresh-water Cyanophyceae. In J. Schmidt, Flora of Koh Chang, Part 4. Bot. Tids., 24: 157-186. 1902. A contribution to the freshwater algae of the north of Ireland. Trans. Roy. Irish Acad., 32(B): 1-100. 1902a. A contribution to the freshwater algae of Ceylon. Trans. Linn. Soc, Bot., 6(Ser. 2): 123-215. 1903. Notes on fresh- water algae. III. Jour. Bot., 41: 33-41, 74-82; Pls. 446-448. 1903a. Scottish fresh-water plankton—No., 1. Jour. Linn, Soc. Bot., 35: 519-556; Pls. 14-18. 1905. Freshwater algae from the Orkneys and Shetlands. Trans. Bot. Soc. Edinburgh, 23: 3-41. 1905a. A further contribution to the freshwater plank- ton of the Scottish Lochs. Trans. Roy. Soc. Edinburgh, 41, Pt. 3: 477-518; Pls. 1-7. 1906. A comparative study of the plankton of some Irish lakes. Trans. Roy. Irish Acad., 33(B): 77-116; Pls. 6-11. 1907. Freshwater algae from Burma, including a few from Bengal and Madras. Ann. Roy. Bot. Gard. Calcutta, 6(Pt. 2): 175-260; Pls. 10-16. 1909. The phytoplankton of the English lake district. Naturalist, 1909: 115-193, 260-321; Pls. 5-7. 1912. On the periodicity of the phytoplankton of some British lakes. Jour Linn. Soc. Bot., 40: 895-432; Pl. 19; Figs. 1-4. Wue pen, R. M. 1939. Notes on New England algae I: Cyclonexis and Acti- desmium. Rhodora, 41: 133-136; Figs. 1-7. 1941. Some observations on freshwater algae of Florida. Jour. Elisha Mitchell Sci. Soc., 57: 261-271; Pls. 5,6. 1942. Notes on New England algae. II. Some interesting New Hampshire algae. Rhodora, 44: 175-187; Figs. 1-6. 1943. Notes on New England algae. III. Some interesting algae from Maine. Farlowia, 1: 9-23; Figs. 1-18. ieeece Gro. C. 1927. The microscopy of drinking water. 586 pp.; Pls. 1-19. 4th ed. New York. Wurerte, Geo. C., and Parker, H. N. 1902. On the amount of oxygen and carbon dioxide in neutral waters and the effect of these gases upon the occurrence of microscopic organisms. Trans. Amer. Microsc. Soc., 23: 108-144. Wuurtrorp, L. A. 1936. New and little known algae from North Carolina. Jour. Elisha Mitchell Sci. Soc., 52: 93-98; Pl. 12. 1938. A new green alga: Oedocladium Lewisii. Bull. Torr. Bot. Club, 65: 23-26; Pl. 2. 1943. The fresh-water algae of North Carolina. Jour. Elisha Mitchell Sci. Soc., 50: 131-170. [ 656 | Wuirney, L. W. 1937. Microstratification of the waters of inland lakes in summer. Science, 85: 224—225. Wuirtson, A. R., DUNNEWALD, T. J., and THompson, Carv. 1921. Soil survey of northern Wisconsin. Wis. Geol. and Nat. Hist. Surv. Bull. 55(Soil Ser., No. 27). Madison. Wuttson, A. R., Gers, W. J., and TostEerup, M. O, 1921. Soil survey of Wau- paca County, Wisconsin. Wis. Geol. and Nat. Hist. Surv. Bull. 54—C (Soil Ser., No. 25). Madison. Wiese, A. H. 1930. Investigations on plankton production in fish ponds. Bull. U. S. Bur. Fish., 46: 187-176. 1930a. Notes on the exposure of young fish to varying concentrations of arsenic. Trans. Amer. Fish. Soc., 60: 270-280. Wiese, A. H., RapvcuirFe, R., and Warp, Fern. 1929. The effects of various fertilizers on plankton production. Trans. Amer. Fish. Soc., 59: 94—105. Wute, N. 1879. Ferskvandsalger fra Novaja Semla samlede af Dr. F. Kjellman paa Nordenskidlds Expedition. Oefv. Kong]. Sv. Vet.-Akad. Forhandl., 36 (No. 5): 13-74. 1881. Om Hvileceller hos Conferva (L) Wille. Ibid., 38(No. 8): 3-26; Pls. 1,2. 1884. Bidrag til Sydamerikas Algflora I-III. Bih. Kongl. Sv. Vet.-Akad. Handl., 8(No. 18): 1-64; Pls. 1-3. 1887. Algologische Mittheilung. I. Ueber die Schwarmzellen und deren Copulation bei Trente- pohlia Mart. Jahrb. Wiss. Bot., 18: 426-434; Pl. 16; Figs. 1-11. 1887a. Ibid., IV. Ueber die Zelltheilung bei Oedogonium. Ibid., 18: 443-454; Pls. 16,17. 1887b. Ibid., VIII. Ueber die Gattung Gongrosira Kiitz. Ibid., 18: 484-491; 1 pl. 1897. Chlorophyceae. In A. Engler and K. Prantl, Die Natiirlichen Pflanzenfamilien. Teil 1, Abt. 2. Leipzig. 1898. Beschreibung einiger Planktonalgen aus norwegischen Siisswasserseen. Biol. Centralbl., 18: 302. 1899. New forms of green algae. Rhodora, 1: 149-150. 1900. Astero- cytis ramosa (Thw.) Gobi. Nyt Mag. f. Natur., 38: 7-10; Pl. 1. 1900a. Algologische Notizen. I-VI. Nyt Mag. f. Natur., 38: 1-27. 1901. Studien iiber Chlorophyceen. I-VII. Videns. Skrift. i Christiania, I. Mat.-Nat. K1., 1900(No. 6): 1-46. 190la. Algologische Notizen. VII-VIII. Nyt Mag. f. Natur., 39: 1-22. 1902. In F. S. Collins, I. Holden, and W. A. Setchell. Phyco- theca boreali-americana. 1908. Zur Entwicklungeschichte der Gattung Oocystis. Ber. d. Deutsch. Bot. Ges., 26A: 812-822; Pl. 15. 1909. Ueber Wittrockiella nov. gen. Nyt Mag. f. Natur., 47: 5-21; Pls. 1-4. 1910. Algologische Notizen. XVI-XXI. Ibid., 48: 281-306; Pls. 1, 2. 1911.+ Conjugatae, Chlorophyceae, Characeae. In A. Engler and K. Prantl, Die Natiirlichen Pflanzenfamilien. Teil 1, Abt. 2: 1-136; Figs. 1-70. Leipzig. 1912. Algologische Notizen. XXII-XXIV. Ueber eine neue epiphytische Art von Lyngbya. Nyt Mag. f. Natur., 51: 1-26. 1914. Botanische und zoologische ergebnisse einer Wis- senschaftlichen Forschungsreise nach den Samoainseln, dem Nauguinea- Archipel und den Salomonsinseln von Marz bis Dezember 1905. Denks. d. Mat.-Nat. KI. d. Kaiser, Akad. Wiss., 91: 1-22; Pls. 1-3 (reprint). 1918. Algologische Notizen XXV-XXIX. Nyt Mag. f. Natur., 56: 1-60; Pls. 1, 2. 1925. Vorarbeiten zu einer Monographie der Chroococcaceen. Ibid., 62: 170-209. WriuiaMson, BEN L., GREENBANK, JOHN, Mutter, E. P., et al. 1938—1939* Investigation of the pollution of the Fox and East Rivers and of Green Bay in the vicinity of the City of Green Bay. Mimeogr. by Wisconsin State Com- mittee on Water Pollution, the State Board of Health and Green Bay Metropolitan Sewerage District. * Witson, Ira T., and OppyKe, Davm F. 1941. The distribution of the chemical constituents in the accumulated sediment of Tippecanoe Lake. Investigation Indiana Lakes and Streams, 2: 16-43. Indianapolis. Witson, L. R. 1987. A quantitative and ecological study of the larger aquatic [ 657 ] plants of Sweeney Lake, Oneida County, Wisconsin. Bull. Torr. Bot. Club, 64: 199-208. 1941.* The larger aquatic vegetation of Trout Lake, Vilas County, Wisconsin. Trans. Wis. Acad. Sci., Arts and Letters, 33: 135-146. Wimmer, E. J. 1929." A study of two limestone quarry pools, Trans. Wis. Acad. Sci., Arts, and Letters, 24: 363-399. Wistoucn, S. M. 1911. Ueber eine durch Oscillaria Agardhii hervorgerfene wasserbliite, sowie iiber Spirulina flavovirens (nova sp.) mihi. Bull. Jard. Imp. Bot. Pierre le Grand, 11(No. 6): 155-161. 1914. Sur les Chrysomona- dines des environs de Petrograd. Jour. Microbiol. Petrograd, 1: 251-278. Wirtrock, V. B. 1867. Algologiska Studier, I-II. Upsala. 1868. Bidrag till kannedomen om Sveriges Zygnemacéer och Mesocarpacéer. Bot. Notiser, 1868: 187-190. 1871. Dispositio Oedogoniacearum suecicarum. Oefv. Kong}. Sv. Vet.-Akad. Forhandl., 27, No. 3(1870): 119-144. 187la. Beitrag zur Kenntnis der Zygnemaceen und Mesocarpeen. Hedwigia, 10: 88. 1872. Om Gotlands och Oelands Sotvattens-alger. Bih. Kongl. Sv. Vet.-Akad. Handl., 1(No. 1): 1-72. 1872a. Oedogoniaceae novae, in Suecia lectae, quas des- cripsit. Bot. Notiser, 1872: 1-8. 1875. Prodromus monographiae Oedogonie- arum. Nova Acta Soc. Sci. Upsala, 9(1874): 1-64; Pl. 1. 1876. In C. F. O. Nordstedt and V. Wittrock. 1876. II. Oedogonieae De Bar., Pringsh. Oefv. Kongl. Sv. Vet.-Akad. Forhandl., 33(No. 6): 44-56. 1877. On the development and systematik arrangement of the Pithophoraceae, a new order of algae. Ibid., Vol. Extra Ordine, Editum, 1877: 1-80; Pls. 1-6. 1878. Oedogonieae Americanae, hucusque cognitae, quas enumeravit. Bot. Notiser, 1878: 133-145, 1878a. On the spore-formation of the Mesocarpeae and especially of the new genus Gonatonema. Bih. Kongl. Sv. Vet.-Akad. Handl., 5(No. 5): 1-18; Pl. 1. 1880. Points-fortekning 6fver Skandinaviens vaxter, Part 4. Lund. 1882. In V. B. Wittrock and C. F. Nordstedt, Algae aquae dulcis exsiccatae. Bot. Notiser, 1882: 51-61. 1886. Om Bu..“‘clearia, ett nytt confervace-sligte. Bih. Kongl. Sv. Vet.-Akad. Handl., 12, Atd. 3, No. I: 3-10; 1 pl. Wirrrock, V. B., and Creve, P. T. 1875. In V. B. Wittrock, Prodromus mono- graphiae Oedogoniearum. Nova. Acta Soc. Sci. Upsala, 9(1874): 1-64; Pl. 1. Wirtrock, V. B., and LunpEtt, P. M. 1871. In V. B. Wittrock, Dispositio Oedogoniacearum suecicarum. Oefv. Kongl. Sv. Vet.-Akad. Forhandl., 27 (1870): 119-144. Wirrrock, V. B., and Norpstept, C. F. O. 1877-1903. Algae aquae dulcis exsiccatae (Nos. 1-1612). 1877. Algae aquae dulcis exsiccatae (Fasc. 1 and 2, Nos. 1-100). Bot. Notiser, 1877: 21-26. 1878. Algae aquae dulcis exsiccatae, etc. (Fasc. 3, Nos. 101-150; Fasc. 4, Nos. 151-200). Ibid., 1878: 67-73. 1879. Algae aquae dulcis exsiccatae (Nos. 201-298). Ibid., 1879: 20-27. 1882. Algae exsiccatae (Nos. 401-500). Ibid., 1882: 51-61. 1884. Algae exsiccatae (Nos. 601-698). Ibid., 1884: 121-128. 1886. Algae exsic- catae (Nos. 701-850). Ibid., 1886: 130-189. 1893. Algae exsiccatae (Nos. 1001-1200). Ibid., 1893: 185-200. Wo te, Francis. 1887.* Freshwater algae of the United States. 364 pp. Pls. 1-210. 2 vols. Bethlehem, Pa. Wozoszynska, J. 1914. In B. Schroeder, Zellpflanzen Oestafricas, gesammelt auf der Akademischen Studienfahrt 1910. V. Studien iiber das Phytoplankton des Viktoriasees. Hedwigia, 55: 184-223; Pls. 2-8. 1916. Polonische Siis- swasser-peridineen. Bull. Inter. Acad. Sci. Cracovie, Math. et Nat. Cl, Reihe B: Biol. Wissen., No. 8-10(1915): 260-285; Pls. 10-14. 1918. Neue Peridineen-Arten, nebst Bemerkungen iiber den Bau der Hiille bei Gymno- und Glenodinium. Ibid., No. 4-6(1917): 114-122; Pls. 11-13. 1917a. [ 658 ] Beitrag zur Kenntnis der Algenflora Litauens. Ibid., No. 4-6(1917): 123- 130. 1919. Die Algen der Tatraseen und Tiimpel. I. Ibid. (1918): 196- 200. 1925. Beitrage zur Kenntnis der Siisswasser-Dinoflagellaten Polens. Polskie Towarzystwo botaniczne (Acta Soc. Bot. Poloniae), 3: 46-69; Figs. 1-7. 1930. Beitrige zur Kenntnis des Phytoplanktons Tropischer Seen. Arch. d’Hydrobiol. u. d'Ichty., 5: 159-160; Figs. 1-6. 1936. Die Algen der Tatraseen und Tiimpel. III. Peridineen im Winterplankton einiger Tatraseen. Ibid., 10: 188-196; Pl. 9. Woop, H. C. 1867. On Oedogonium Huntii. Proc. Amer. Philos. Soc., 10: 333-335. 1869.* Prodromus of a study of the fresh water algae of eastern North America. Ibid., 11: 119-145. 1874.* A contribution to the history of the fresh-water algae of North America. Smiths. Contrib. Knowledge, 19 (No. 241): 1-262; Pls. 1-21. Woop, R. D. 1947. Characeae of the Put-in-Bay region of Lake Erie (Ohio). Ohio Jour. Sci., 47: 240-258; Pls. 1-3. 1949. The Characeae of the Woods Hole region, Massachusetts. Biol. Bull., 96( No. 2): 179-203; Pls. 1-4. Woops, A. F. 1894. Coleochaetaceae, Characeae. Flora of Nebraska, Part II. Lincoln, Nebr. Woronicuin, N. N. 1923. Algae nonnullae novae e Caucaso. I. Not. Syst. Inst. Crypt. Horti Bot. Petropol., 2(No. 7): 97-100. 1923a. Ibid. II. Ibid., 2, (No. 8): 113-116. Ibid. Ill. Ibid., 2(No. 9): 140-142. 1923b. Ibid. IV. Ibid., 2(No. 12): 192. 1924 Ibid. V. Ibid., 3(No. 6): 84-88. 1924a. Ibid. VI. Ibid., 83(No. 7): 102-106. 1924b. Matériaux pour la flore algologique des eaux douces du Caucase. V. Chlorophyceae. Zeit. Russ. Bot. Ges., 8 (1923): 78-86. 1925. Materialien zur Flora des Siisswasseralgen des Kau- kasus. Trav. Stat. Biol. du Caucas. du Nord, 1(1925): 1-7. 1925a. Beitrage zur Kenntnis der Siisswasseralgen des Kaukasus, II, III. Arch. Russ. Protist., 4, No. 3/4: 199-216. 1930. [Algen des Polar- und des Nord-Urals]. Trav. Soc. Nat. Leningrad Soc. Bot., 60(No. 3): 3-80. Worontn, M. 1869. Beitrag zur Kenntniss der Vaucherien. Bot. Zeit., OT: 137-144, 153-162; Pls. 1, 2. Wortuincton, E. B. 1939. Freshwater biology and its applications: Intro- duction. Ann. Appl. Biol., 26: 165-167. YamManoucul, S. 1913. Hydrodictyon africanum, a new species. Bot. Gaz., 55: 74-79; Figs. 1-6. Younc, O. W. 1945.* A limnological investigation of periphyton in Douglas Lake, Michigan. Trans. Amer. Microsc. Soc., 64: 1-20. ZacHarias, Otro. 1897. Biologische Beobachtungen an den Versuchsteichea des Schles. Fischereivereins zu Trachenberg. Forsch. Biol. Stat. z. Plon, 5: 10-28. 1898. Untersuchungen iiber das Plankton der Teichgewisser. [bid., 6: 89-193; Pl. 4. 1899. Zur Kenntnis der Plankton siichsischer Fischteiche. Ibid., 7: 78-95. 1903. Zur Kenntnis der niedern Flora und Fauna holsteinis- cher Moorsiimpfe. Ibid., 10: 223-289. 1903a. Drei neue Pflanzenflagellaten des Siisswassers. Ibid., 10: 290-303. 1907. Planktonalgen als Molluskennah- rung. Arch. f. Hydrobiol. u. Planktonk., 2: 358-361. 1911. Das Siisswasser- Plankton. Einfiihrung in die freischwebende Organismenwelt unserer teiche, Fliisse und Seebecken. Leipzig. ZaLEssky, M. D. 1926. Sur les nouvelles algues découvertes dans le saprope- logéne du Lac Beloe et sur une algue sapropélogéne Botryococcus Braunii Kitzing. Rev. Gen. Bot., 38: 31-42. ZaNaARDINI, G. 1858. Plantarum in mari rubro hucusque collectarum enume- ratio. Mem. Ist. Veneto, 7: 209-309; Pls. 3-14. ZANEVELD, J. S. 1939. Nitella madagascarensis, nov. spec., with notes on the Charophyta of Madagascar. Blumea, 3: 372-387. [ 659 ] ZeEDERBAUER, E. 1904. Geschlechtliche und ungeschlechtliche Fortpflanzung von Ceratium hirundinella. Ber. d. Deutsch. Bot. Ges., 22: 1-8. ZELLER, G. H. von. 1873. Algae collected by Mrs. S. Kurz in Arracan and British Burma. Jour. Asiatic Soc. Bengal, 42: 175-193. ZIMMER, CarL. 1899. Das Plankton des Oderstromes. A. Das tierische Plankton der Oder. Forsch. Biol. Stat. z. Plon, 7: 1-14. ZIMMERMANN, W. 1927. Ueber Algenbestinde aus der Tiefenzone des Bodensees. Zur Oekologie und Soziologie der Tiefseepflanzen. Zeitsch. f. Bot., 20: 1-35; Pls. 1, 2; Figs. 1-5. ZoBELL, CLaupE E. 1940. Some factors which influence oxygen consumption by bacteria in lake water. Biol. Bull., 78: 388-402. Zuxat, H. 1894. Neue Beobachtungen uber einige Cyanophyceen. Ber. d. Deutsch. Bot. Ges., 12: 256-266. References for Desmids and Diatoms Fritsch, F. E. 1935. Structure and Reproduction of the Algae. Vol. I. 791 pp. Cambridge. Hustedt, F. 1929. Die Kieselalgen. In: Rabenhorst, L. Kryptogamen-Flora Deutschlands, Osterreich, und der Schweiz. Bd. VII. Irénée-Marie, Fr. 1939. Flore Desmidiale de la Region de Montréal. 547 pp. Laprairie, Canada. Krieger, W. 1937. Die Desmidiaceen Europas mit Berucksichtigung der ausser- europdischen Arten. In: Rabenhorst, L. Kryptogamen-Flora Deutschlands, Osterreich und der Schweiz. Bd. XIII. Prescott, G. W. 1964. How to Know the Fresh-Water Algae. 272 pp. Wm. C. Brown Co. Smith, G. M. 1924. Phytoplankton of the Inland Lakes of Wisconsin. Part II. Desmidiaceae. Wisconsin Geol. & Nat. Hist. Surv., Bull. 57 (II). 227 pp. Madison. Van Heurck, Henri. 1896. A Treatise on the Diatomaceae. 558 pp. William Wesly & Son, London. West, W. and West, G. S. 1904-1912. A Monograph of the British Desmidia- ceae. Vols. I-IV. and Carter, Nellie. 1924. Ibid. Vol. V. Ray Society, London. [ 660 ] PLATES Figs. 1, 2. Fign3: Fig. 4. Fig. 5. Figs. 6, 7. Figs. 8, 9. Figs. 10, 11. Fig. 12. Figs. 13, 14. Figs. 15, 16. Figs. 17-19. Fig. 20. Fig. 21. Fig. 22. Fig. 23. Figs. 24-26. iPreAmeel Pyramimonas tetrarhynchus Schmarda, x 750 (after Smith ) Chlamydomonas angulosa Dill, x 750 Chlamydomonas Cienkowskii Schmidle, x 750 Chlamydomonas Dinobryoni G. M. Smith, x 1000 (redrawn from Smith ) Chlamydomonas epiphytica G. M. Smith, x 750 (redrawn from Smith ) Chlamydomonas globosa Snow, x 1000 (8 after Smith) Chlamydomonas polypyrenoideum Prescott, x 1000 Chlamydomonas pseudopertyi Pascher, x 500 Chlamydomonas Snowii Printz, x 1000 (redrawn from Smith ) Chlamydomonas sphagnicola Fritsch & Takeda, x 1000 Carteria Klebsii (Dang.) Dill, x 1000 (redrawn from Smith Carteria cordiformis (Carter ) Diesing, x 1000 (redrawn from Smith ) Gonium pectorale Mueller, x 500 Gonium sociale (Duj.) Warming, x 750 Pandorina morum (Muell.) Bory, x 500 Eudorina elegans Ehrenberg: 24 and 25, x 440; 26, formation of daughter colonies, x 440 [ 662 ] Fig. 1. Fig. 2 Fig. 3. Fig. 4. Fig. 5. PLATE 2 Pleodorina californica Shaw, x 250 Haematococcus lacustris (Girod.) Rostaf., x 1000 Pleodorina illinoisensis Kofoid, x 450 Volvox aureus Ehrenberg, x 266 (redrawn from Smith ) Volvox globator Linnaeus, x 266 (after Smith) [ 664 ] ni © ass ‘Ss So: ot POCONO er aan ee woooe - aos at : 5) mer? RY eee 4 Sree Rey ete 6 <>. Ce) faite La Shee y) (a) OR? Or eeeer ore ae SACO Lest SOOO RISE SOI CRA IRCD ate ORS Sac aves nee sisi aire aca Z Joy. Roe Scout Be ees se eaves igo. Fig. 2. Figs. 3—5 Figs. 6, 7. Figs. 8, 9. Figs. 10, 11. Fig. 12. Figs. 18, 14. Fig. 15. Fig. 16. Rigel, PLATE 3 Spondylomorum quaternarium Ehrenberg, x 440 (af- ter Stickney ) Spondylomorum quaternarium Ehrenberg: single cell, x 500 (after Jacobsen, ex Smith) Haematococcus lacustris (Girod.) Rostaf. 3, swim- ming cell; 4 and 5, encysted cells, x 750 Sphaerocystis Schroeteri Chodat, x 500 Palmella mucosa Kuetzing: 8, habit of colony, x 114; 9, portion of colony, x 440 Gloeocystis planctonica (West & West) Lemmermann, x 500 Volvox tertius A. Meyer, x 266 (redrawn from Smith ) Elakatothrix gelatinosa Wille: 13, x 1000; 14, x 500 (after Smith) Gloeocystis vesiculosa Naegeli, x 500 Gloeocystis gigas (Kuetz.) Lagerheim, x 1000 Gloeocystis ampla (Kuetz.) Lagerheim x 440 [ 666 | 2® EPO, GPE Gs Po, FE 2 ae) PLATE 4 Figs. 1, 2. Elakatothrix viridis (Snow) Printz: 1, x about 620 (re- drawn from Smith); 2, x 440 Figs. 3, 4. Palmodictyon varium (Naeg.) Lemmermann, x 500 Figs. 5, 6. Palmodictyon viride Kuetzing, x 500 Figs. 7-9. Stylosphaeridium stipitatum (Bachm.) Geitler & Gi- mesi: 7, x 500; 8 and 9, single cells, x 1000 Fig. 10. Asterococcus superbus (Cienk.) Scherffel, x 440 Big. 1, Asterococcus limneticus G. M. Smith, x 500 Figs. 12-14. Schizochlamys compacta Prescott, x 500 Fig. 15. Schizochlamys gelatinosa A. Braun, x 500 [| 668 ] Figs, 1, 2. Figs. 3, 4. Fig. 5. Fig. 6. Figs. 7, 8. Fig. 9. Fig. 10. Fig, AT: PLATE 5 Tetraspora cylindrica (Wahl.) C. A. Agardh: 1, habit x 1; 2, cell arrangement, x 220 Tetraspora gelatinosa (Vauch.) Desvaux: 3, habit of young colony, x 5; 4, habit of older colony, x 1 Uronema elongatum Hodgetts, x 440 Tetraspora lamellosa Prescott, x 500 Apiocystis Brauniana Naegeli: 7, colony, x 440; 8, single cell, x 1500 Tetraspora lubrica (Roth) C. A. Agardh: portion of old thallus, x 1 Apiocystis Brauniana Naegeli, « 300 Tetraspora lacustris Lemmermann, x 440 [ 670 ] PLATE 6 Big. Ulothrix aequalis Kuetzing, « 500 Bigs 2; Ulothrix cylindricum Prescott, x 500 Fig. 3. Ulothrix subtilissima Rabenhorst, « 750 Fig. 4. Hormidium Klebsii G. M. Smith, « 500 Fig. 5. Stichococcus bacillaris Naegeli, x 1500 Fig. 6. Stichococcus scopulinus Hazen, x 750 Figs. 7,8. | Stichococcus subtilis (Kuetz.) Klercher, x 750 Figs.9,10. Geminella crenulatocollis Prescott, x 750 Fig. 11. Ulothrix subconstricta G. S. West, x 750 (after Smith) Fig. 12. Ulothrix tenerrima Kuetzing, 500 Fig. 13. Ulothrix variabilis Kuetzing, « 750 Fig. 14. Ulothrix zonata (Weber & Mohr) Kuetzing, x 750 Fig. 15. Geminella interrupta (Turp.) Lagerheim, x 500 Fig. 16. Geminella mutabilis (de Bréb.) Wille, x 440 Big 7, Geminella minor (Naeg.) Heering, x 440 [ 672 ] PLATE 7 Figs. 1, 2. Hormidiopsis ellipsoideum Prescott, x 750 Figs. 3-5. Radiofilum irregulare (Wille) Brunnthaler: 3, x 1000; 4, x 750; 5, x 440 Fig. 6. Radiofilum conjunctivum Schmidle, x 750 Figs. 7-9. Binuclearia tatrana Wittrock, x 440 Fig. 10. Radiofilum flavescens G. S. West, x 590 Figs. 11-13. Schizomeris Leibleinii Kuetzing: 11, x 220; 12, x 500; 13, x 500 [ 674 ] 9,900.0 C0009 atelier ree = 2.200000 00° 9 9000000605, 9009000 } ; EE es Pay sae grey cr By \| Sees MW Y2:3 sicece Meee, . Uf He oe Hee i Hae oH 8 TRE Eb ei eee e% i A : ee fo ML es Ee ey |e |e | | | a Sf Py fe | Tees |e leone 5 < i : Pe | OT Gel pate acca Bo bai H 2 \ ” LA arent Ree of ee er | sea eae ry s., : Pe: cans z tiny 900099500, 000 200.08. “ %,, PLATE 8 Fig. 1. Microspora crassior (Hansg.) Hazen, x 750 Fig. 2. Microspora Loefgrenii (Nordst.) Lagerheim, x 750 Fig. 3. Microspora pachyderma (Wille) Lagerheim, x 750 Fig. 4. Microspora floccosa (Vauch.) Thuret, x 750 Fig. 5. Microspora Willeana Lagerheim, x 1000 Figs. 6,7. Microspora stagnorum (Kuetz.) Lagerheim: 6, x 1125; 7, x 750 Fig. 8. Microspora amoena (Kuetz.) Lagerheim, x 660 Fig. 9. Microspora tumidula Hazen, x 1125 [ 676 ] ) Jee ee PLATE 9 Figs. 1,2. Cylindrocapsa geminella var. minor Hansgirg, x 750 Figs. 3,4. Cylindrocapsa geminella Wolle, oogonia: 3, x 750; 4, x 1500 Figs. 5,6. Cylindrocapsa conferta W. West, x 750 Figs. 7,8. Stigeoclonium nanum Kuetzing, x 750 Fig. 9. Stigeoclonium polymorphum (Franke) Heering, x 750 Fig. 10. Protoderma viride Kuetzing, x 750 [ 678 | PLATE 10 Figs. 1,2. Stigeoclonium lubricum (Dillw.) Kuetzing, x 440 Figs. 3,4. Stigeoclonium subsecundum Kuetzing: 3, x 500; 4, x 440 Figs.5-7. Protococcus viridis C. A. Agardh, x 1000 [ 680 ] ree Bee ; ee ry ee ec ee mee ee a) LLL Prade ul ~ Figs. 1,2. Stigeoclonium flagelliferum Kuetzing, x 440 Fig. 3. Stigeoclonium stagnatile (Hazen) Collins, x 440 Fig. 4. Microthamnion Kuetzingianum Naegeli, x 440 Figs. 5,6. Microthamnion strictissimum Rabenhorst: 5, x 1000; 6, base of plant, x 1000 [ 682 ] PLATE 12 Figs. 1-4. Stigeoclonium pachydermum Prescott: 1, x 100; 2, x 500; 3 and 4, x 250 Figs. 5-8. Sphaeroplea annulina (Roth) C. A. Agardh: 5, portion of vegetative cell, x 650; 6 and 7, germlings, x 325; 8, portion of oogonial cell, x 650 (after Smith, courtesy McGraw-Hill Co. ) Figs.9,10. Stigeoclonium pachydermum Prescott: forms of branch- es, x 250 [ 684 ] Ze fF S= Bie Figs. 2, 3. Figs. 4, 5. Figs. 6, 7. PLATE 13 Stigeoclonium attenuatum (Hazen) Collins, x 750 Chaetophora pisiformis (Roth) C. A. Agardh: 2, habit, x 2; 3, portion of thallus, x 500 Chaetophora attenuata Hazen: 4, x 440; 5, tip of branch, x 750 Chaetonema irregulare Nowakowski: 6, filament with oogonium, x 500; 7, sporangia, x 500 [ 686 ] Figs. 1, 2. Figs. 3, 4. Fig. 5. Figs. 6, 7. Fig. 8. Fig. 9. Fig. 10. Fig. 11. PLATE 14 Chaetophora incrassata (Huds.) Hazen: 1, habit, x 1%; 2, habit of branching in main axis, x 225 Chaetophora elegans (Roth) C. A. Agardh: 3, habit, x 1; 4, x 825 Chaetosphaeridium Pringsheimii Klebahn, x about 1000 (redrawn after Klebahn, ex Collins ) Chaetosphaeridium globosum (Nordst.) Klebahn, x 750 Chaetosphaeridium ovalis G. M. Smith, x about 1000 (after Smith ) Entocladia polymorpha (G.S. West) G. M. Smith, x 440 Protoderma viride Kuetzing, x 750 Chaetophora incrassata (Huds.) Hazen: tip of branch, x 500 [ 688 ] ) SU QD i << Dig | A Fig. 1 Figs. 2, 3. Fig. 4. Fig. 5. Fig. 6. Prates5 Draparnaldia acuta (C. A. Ag.) Kuetzing: portion of main filament, x 75 Draparnaldia platyzonata Hazen: 2, portion of main fila- ment, x 150; 3, x 350 Draparnaldia plumosa (Vauch.) C. A. Agardh: portion of main filament, x 165 Draparnaldia glomerata (Vauch.) C. A. Agardh: portion of main filament, x 150 Pseudulvella americana (Snow) Wille: portion of disc- like thallus, x 440 [ 690 | = ei eae LIN COSY Ny 7 "Ga J Pirate 16 Figs. 1-5. Draparnaldia Judayi Prescott: 1, portion of main axis showing sparsely branched fascicles; 2-4, forms of setae, some of which replace lateral branches of main filament; 5, whorled arrangement of fascicles; all x 500 Fig. 6. Chaetopeltis orbicularis Berthold: habit on filamentous alga, x 440 [ 692 ] Fig. 1. Figs. 2, 3. Fig. 4. Figs. 5-7. Figs. 8, 9. PLATE 17 Aphanochaete polychaete (Hansg.) Fritsch, x 500 (re- drawn from West and Fritsch, courtesy of the Mac- millan Publishing Company ) Aphanochaete repens A. Braun, x 440 Aphanochaete vermiculoides Wolle, x 750 Coleochaete divergens Pringsheim: 5 and 6, antheridia, x 150; 7, oogonium, x 220 Coleochaete irregularis Pringsheim: 8, antheridia, x 440; 9, oogonium, x 220 [ 694 ] PuatTeE 18 Figs. 1, 2. Coleochaete Nitellarum Jost: 1, habit on Nitella; 2, oogonium, x 440 Figs. 3-5. Coleochaete orbicularis Pringsheim: 3 and 4, x 440; 5, habit on grass, x about 20 Fig. 6. Coleochaete soluta (de Bréb.) Pringsheim, x 500 Figs. 7, 8. Coleochaete pulvinata A. Braun, x 220 Fig. 9. Coleochaete scutata de Brébisson, x 75 Figs. 10,11. Coleochaete soluta (de Bréb.) Pringsheim: oogonia, x 100 [ 696 ] (i N\A PLATE 19 Figs.1,2. | Dicranochaete reniformis Hieronymus, x 1000 Fig. 3. Gongrosira Debaryana Rabenhorst, x 500 Figs. 4-8. | Trentepohlia Iolithus (L.) Wallroth: 4-5, filaments, x 125; 6 and 7, tips of branches and sporangia, x 500; 8, filaments, x 125 Figs. 9-11. Cladophora crispata (Roth) Kuetzing: 9 and 10, x 200; 11, habit of branching (diagram) [ 698 ] PuAaTE 20 Figs. 1-6. Cladophora fracta (Dillw.) Kuetzing: various expres- sions of the filaments; 1, habit of branching (diagram); 2 and 3, x 200; 4, x 100; 5, branch origin, showing lamellations of wall, x 250; 6, old, ‘winter’ stage, x 200 Fig. 7. Cladophora fracta var. lacustris (Kuetz. ) Brand, x 500 Figs. 8,9. Cladophora glomerata (L.) Kuetzing: 8, portion of main filament, x 75; 9, habit of branching, x 350 [ 700 ] Figs. 1, 2. Fig. 3. Figs. 4, 5. Figs. 6-8. PLATE 21 Cladophora glomerata (L.) Kuetzing: 1, x 37%; 2, x 225 (redrawn from Smith) Cladophora glomerata fa. Kuetzingianum (Grunow) Heering, x 150 Cladophora insignis (C. A. Ag.) Kuetzing, x 225 Cladophora oligoclona Kuetzing: 6, x 100; 7, habit of branching; 8, portion of main filament, x 100 [ 702 ] PLATE 22 Figs. 1-4. Cladophora profunda var. Nordstedtiana Brand, x 100 Figs. 5,6. Pithophora Mooreana Collins, x 60 Figs. 7-10. Pithophora oedogonia (Mont.) Wittrock: 7, x 25; 8, x 100; 9, x 30; 10, portion of cell showing chloroplasts, 4125 [ 704 ] \ \ / Fig. 1. Fig. o: Fig. 3. Figs. 4, 5. Figs. 6, 7. Figs. 8-12. PLATE 23 ?Rhizoclonium crassipellitum West & West fa., x 150 Rhizoclonium fontanum Kuetzing, x 440 Rhizoclonium heiroglyphicum (C. A. Ag.) Kuetzing, x 150 Rhizoclonium Hookeri Kuetzing: 4, large form, x 150; 5x15 Rhizoclonium Hookeri Kuetzing, drawn from an her- barium specimen: 6, x 100; 7, x 75 Basicladia chelonum (Collins) Hoffmann & Tilden: 9-11 (redrawn from Smith, courtesy McGraw-Hill Co.), x 125; 12, enlarged cells in upper limits of fila- ment showing papilla-like pores in sporangia (from specimens collected in Michigan ), x 100 [ 706 ] Fig. 1. Figs. 2, 3. Fig. 4. Figs. 5, 6. Biggie Fig. 8. Fig. 9. PLATE 24 Bulbochaete hiloensis (Nordst.) Tiffany, x about 355 (redrawn from Tiffany ) Oedogonium verrucosum Hallas, x about 285 (redrawn from Hallas, ex Tiffany Oedogonium hispidum Nordstedt, x 300 Pithophora varia Wille, x 145 Bulbochaete obliqua Lundell, x 255 Bulbochaete valida Wittrock, « 290 Geminella ordinata (West & West) Heering, x 500 [ 708 ] Bigs: 12. Fig. 3. Fig. 4. Fig. 5. FIGS G7. Fig. 8. PLATE 25 Bulbochaete alabamensis Transeau & Brown, x 290 Bulbochaete borealis Wittrock, x 590 Bulbochaete angulosa Wittrock & Lundell, x 590 Bulbochaete congener Hirn, x 590 Bulbochaete dispar Wittrock, x 300 Bulbochaete crassa Pringsheim, x 590 [710 ] Fig. 1. Fig. 2: Fig. 3. Figs. 4-6. Fig, 7. Fig. 8. Fig. 9. PLATE 26 Bulbochaete gigantea Pringsheim, x 500 Bulbochaete Furberae Collins, x 590 Bulbochaete elatior Pringsheim, x 590 Bulbochaete insignis Pringsheim: 4, x 590; 5 and 6, x 300 Bulbochaete minor A. Braun, x 590 Bulbochaete intermedia var. depressa Wittrock, x 500 Bulbochaete intermedia Debary, x 590 [ 712 ] Figs. 1, 2. Fig. 3. Figs. 4, 5. Fig. 6. Figs. 7, 8. Figs. 9, 10. Pare. 27 Bulbochaete mirabilis Wittrock, x 500 Bulbochaete Nordstedtii Wittrock, x 590 Bulbochaete polyandria Cleve: 4, x 590; 5, androspo- rangia, x 590 Bulbochaete praereticulata Jao, x 330 Bulbochaete pygmaea Pringsheim: 7, x 590; 8, x 625 Bulbochaete rectangularis Wittrock: 9, x 312; 10, x 590 [714 ] PLATE 28 Figs. 1, 2. Bulbochaete regalis (Wittr.) Tiffany, x 300 Figs. 3. 4. Bulbochaete repanda Wittrock: 3, x 312; 4, x 590 Fig. 5. Bulbochaete reticulata Nordstedt, x 500 Fig. 6. Bulbochaete scrobiculata ( Tiff.) Tiffany, x 590 Figs. 7-9. Bulbochaete varians Wittrock: 7 and 8, x 590; 9, x 312 Figs. 10,11. Bulbochaete setigera (Roth) C. A. Agardh: 10, x 500; 11, x 1600 Fig. 12. Bulbochaete sessilis Wittrock, x 440 [ 716 } PLATE 29 Figs. 1, 2. Oedogonium angustum (Hirn) Tiffany, x 312 Figs. 3, 4. Oedogonium anomalum Hin: 3, x 180; 4, x 375 Figs. 5, 6. Oedogonium capilliforme var. australe Wittrock, x 375 Figs. 7, 8. Oedogonium cardiacum (Hass.) Wittrock: 7, x 220; 8, x 440 Figs.9-11. Oedogonium diversum (Hirn) Tiffany, x 250 Figs. 12-14. Oedogonium gracilius (Wittr.) Tiffany: 12, x 625; 18 and 14, x 825 Figs. 15-17. Oedogonium grande Kuetzing, x 275 Fig. 18. Oedogonium grande var. aequatoriale Wittrock, x 300 [718 ] Figs, 1, 2: Figs. 3, 4. Figs. 5, 6. Hig: 7. Figs. 8-10. Figs. 11, 12. Figs. 13-15. PLATE 30 Oedogonium australe (G. S. West) Tiffany, x 500 Oedogonium giganteum Kuetzing: 3, x 220; 4, x 590 Oedogonium Boscii (Le Cl.) Wittrock, x 285 Oedogonium crenulatocostatum Wittrock, x 590 Oedogonium Kjellmanii var. granulosa Prescott: 8, x 285; 9, x 440; 10, x 285 Oedogonium exocostatum Tiffany: 11, x 500; 12, x 275 Oedogonium crenulatocostatum var. cylindricum (Hirn) Tiffany: 13, x 275; 14, x 590; 15, x 275 [ 720 ] PLATE 31 Figs. 1-3. Oedogonium globosum Nordstedt: 1, x 590; 2 and 3, x 800 Fig. 4. Oedogonium Hirnii Gutwinski, « 590 Figs. 5, 6. Oedogonium intermedium Wittrock: 5, x 270; 6, x 590 Figs. 7,7a. | Oedogonium oviforme (Lewin) Hirn, x 590 Figs. 8, 9. Oedogonium areolatum Lagerheim: 8, x 500; 9, x 275 Figs. 10,11. Oedogonium argenteum Hin: 10, x 600; 11, x 590 [ 722 ] Neier oo 82 Fo. y99 S000 00 Poe PLATE 32 Figs. 1,2. Oedogonium Landsboroughii (Hass.) Wittrock: 1, x Tis 2X 150 Figs. 3,4. Oedogonium plagiostomum Wittrock: 3, x 600; 4, x 300 Figs. 5,6. Oedogonium rivulare (Le Cl.) A. Braun: 5, x 250; 6, x 125 Figs. 7-9. Oedogonium sociale Wittrock: 7 and 8, x 275; 9, x 590 Fig.10._ | Oedogonium varians Wittrock & Lundell, x 600 Fig.11. | Oedogonium tyrolicum Wittrock, = 500 Fig 2, Oedogonium fennicum ( Tiff.) Tiffany, x 500 Fig.13. | Oedogonium fragile Wittrock, x 590 [ 724 ] Figs. 1-3. Figs. 4, 5. igs On. Fig. 8. Figs. 9, 10. Figs. 11, 12. PLATE 33 Oedogonium plusiosporum Wittrock, x 340 Oedogonium suecicum Wittrock, x 590 Oedogonium oviforme fa. gracile Prescott, x 590 Oedogonium patulum Tiffany, x 590 Oedogonium urceolatum Nordstedt & Hirn: 9, x 127; 10, x 590 Oedogonium carolinianum Tiffany: 11, x 500; 12, x 300 [ 726 ] Rigs. 1-3: Fig. 4. Figs. 5, 6. Figs. 7-9. Fig. 10. Figs. 11, 12. Figs. 13, 14. Figs. 15, 16. PLATE 34 Oedogonium Reinschii Roy, x 700 Oedogonium psaegmatosporum Nordstedt, x 590 Oedogonium pyriforme Wittrock, x 675 Oedogonium minus (Wittr.) Wittrock: 8, oogonium with extrusions of mucilage through the punctae of the wall; all x 600 Oedogonium Kurzii Zeller, x 300 Oedogonium autumnale Wittrock: 11, x 675; 12, x 375 Oedogonium gracilimum Wittrock & Lundell, on fila- ment of Microspora, x 750 Oedogonium Gunnii Wittrock, x 590 [ 728 ] Figs. 1-3. Fig. 4. Figs. 5-7. Figs. 8, 9. Figs. 10, 11. Figs. 12, 13. PLATE 85 Oedogonium iowense Tiffany: 1, x 375; 2, x 700; 3, x 500 Oedogonium pseudo-Boscii Hirn, x 500 Oedogonium inclusum Hirn: 5, x 500; 6 and 7, x 250 Oedogonium Borisianum (Le Cl.) Wittrock: 8, x 125; 9, x 500 Oedogonium echinospermum A. Braun, x 300 Oedogonium Wolleanum Wittrock: 12, x 350; 18, x 175 [ 730 ] Figs. 1-3. Figs. 4, 5. Figs. 6, 7. Figs. 8, 9. Fig. 10. Figs. 11-14. Figs. 15, 16. Figs. 17-19. Figs. 20, 21 PLATE 36 Oedogonium Pringsheimii Cramer: 1, x 625; 2 and 3, «312 Oedogonium pratense Transeau, x 590 Oedogonium porrectum Nordstedt & Hirn, x 590 Oedogonium pisanum Wittrock, x 600 Oedogonium nanum Wittrock, x 350 Oedogonium microgonium Prescott, x 675 Oedogonium abbreviatum (Hirn) Tiffany, x 590 Oedogonium Smithii Prescott: 17 and 18, x 500; 19, x 650 Oedogonium epiphyticum Transeau & Tiffany, x 500 [ 732 ] Bigs. 12. Fig. 3. Figs. 4, 5. Fig. 6. Figs. 7-9. Fig. 10. Pgs ae: Figs. 13, 14. Figs. 15, 16. PLATE 37 Oedogonium inconspicuum Hirn, x 650 Oedogonium bohemicum Hirn, x 590 Oedogonium spurium Hirn, x 590 Oedogonium psaegmatosporum Nordstedt, x 590 Oedogonium ambiceps (Jao) Tiffany, x 590 Oedogonium trioicum Woronichin, x 590 Oedogonium pusillum Kirchner: 11, x 730; 12, x 600 Oedogonium Woyliei Tiffany, « 355 Oedogonium calvuum Wittrock, x 590 [ 734 ] Figs. Figs. Figs. Figs. Figs Figs Meee 3, 4. 3), (0) 138: oh IOS » L112: PLATE 38 Oedogonium paucostriatum Tiffany: 1, x 600; 2, x 300 Oedogonium spheroideum Prescott: 3, x 300; 4, x 600 Oedogonium punctatostriatum DeBary: 5, x 300; 6, x 600 Oedogonium Welwitschii West & West, x 590 Oedogonium Pringsheimii var. Nordstedtii (Witt) Wittrock: 9, x 365; 10, x 590 Oedogonium tapeinosporum Wittrock, x 700 [ 736 ] Fig. 10. Pigs ii 12: PLATE 389 Oedogonium Sawyerii Prescott, x 590 Oedogonium sexangulare Cleve: 2, x 600; 3, x 300 Oedogonium gallicum Hirn, x 590 Oedogonium subsexangulare Tiffany, x 450 Oedogonium perfectum (Hirn) Tiffany: 6, x 360; 7, x 175 Oedogonium Westii Tiffany, x 325 Oedogonium rugulosum fa. rotundatum (Hirn) Tif- fany, x 500 Oedogonium striatum Tiffany, x 175 Oedogonium rugulosum fa. rotundatum (Hirn) Tif- fany, x 500 [ 788 ] Fig. 1. Fig. 2. Figs. 3-5. Figs, 6; 7. Fig. 8. Fig. 9. Fig. 10. PLATE 40 Oedogonium spiraldens Jao, x 625 Oedogonium sinuatum fa. seriatum Prescott, « 300 Oedogonium undulatum (de Bréb.) A. Braun, x 350 Oedogonium Areschougii var. contortofilum Jao, « 625 Oedogonium subplenum Tiffany, x 750 Oedogonium pseudoplenum Tiffany, x 625 Oedogonium hians Nordstedt & Hirn, « 375 [ 740 ] larger ale Fig. 2. Figs. 3, 4. Figs. 5, 6. Fige 7. Figs: 3, 9: Big. 10; Fig wale Fig. 12. PLATE 4] Oedogonium macrandrium Wittrock, x 625 Oedogonium decipiens var. africanum Tiffany, x 625 Oedogonium brasiliense Borge: 3, x 200; 4, x 440 Oedogonium acrosporum var. bathmidosporum (Nordst.) Hirn fa., x 625 Oedogonium acrosporum DeBary, x 750 Oedogonium orientale Jao, x 400 Oedogonium acrosporum var. majusculum Nordstedt, x 300 Oedogonium Croasdaleae Jao, x 340 Oedogonium macrospermum West & West, x 625 [ 742 ] PLATE 42 Figs. 1-3. Oedogonium oelandicum var. contortum Prescott, x 450 Figs. 4-6. Oedogonium Kozminskii Prescott: 4, x 750; 5, x 375 Figs. 7-9. Oedogonium polyandrium Prescott: 7 and 8, x 625; 9, x 700 Fig. 10. Oedogonium hians Nordstedt & Hirn, x 500 Figs. 11,12. Oedogonium decipiens var. dissimile (Him) Tiffany, x 625 Figs. 13,14. Oedogonium decipiens Wittrock: 13, x 700; 14, x 350 [ 744 ] Figel Figs. 2, 3. Figs. 4, 5. Figs. 6, 7. Fig. 8. Figs. 9-11. iat 1D Fig. 12x, Figs. 13, 14. Fug.) Lo: Bags: N67, Figs. 18, 19. Fig. 20. PLATE 43 Oedogonium minisporum Taft, x 365 (redrawn from are) Oedogonium oblongum var. minus Taft, x about 500 (redrawn from Taft ) Oedogonium argenteum fa. michiganense Tiffany, x about 240 (redrawn from Ackley ) Oedogonium Tiffanyi Ackley, x about 200 (redrawn from Tiffany ) Oedogonium Richterianum Lemmermann, x about 225 (redrawn from Tiffany ) Oedogonium michiganense Tiffany, x about 250 (re- drawn from Tiffany ) Oedogonium Sodiroanum Lagerheim, x about 300 (re- drawn from Tiffany ) Oedogonium capillare (L.) Kuetzing, x about 280 Oedogonium upsaliense Wittrock, x about 250 (re- drawn from Tiffany ) Oedogonium princeps (Hass. ) Wittrock, x about 185 Oedogonium americanum Transeau, x about 200 (re- drawn from Tiffany ) Oedogonium Vaucherii (Le Cl.) A. Braun, x about 260 (redrawn from Tiffany ) [ 746 ] Toe eT i Fig. Sr, V5 eh Figs. 9, 10. Pigs. 11, 12. Fig. 18. Figs. 14, 15. 6 PLATE 44 Oedogonium spirostriatum Tiffany, x 340 (redrawn from Tiffany ) Oedogonium latiusculum Tiffany, x 440 Oedogonium undulatum fa. senegalense (Nordst.) Hirn, x 500 Oedogonium crispum (Hass.) Wittrock, x 300 (re- drawn from Tiffany ) Oedogonium angustissimum West & West, x 775 Oedogonium capilliforme Kuetzing; Wittrock, « 425 Oedogonium crassum ( Hass.) Wittrock, x 275 Oedogonium mitratum Hirn, x 300 (redrawn from Tiffany ) Oedogonium cyathigerum fa. ornatum (Wittr.) Hirn, Slo Oedogonium rugulosum Nordstedt, 590 [ 748 ] Bie i. Fig. 2. Fig. 3. Figs. 4, 5. Figs. 6, 7. Figs. 8-10. Fig. 11. Figs. 12, 13. Fig. 14. Fig. 15. Fig. 16. Fig. 17. Fig. 18. Big 9: Fig. 20. Fig. 21. Figs. 22, 23. PLATE 45 Chlorococcum humicola (Naeg.) Rabenhorst, x 500 Golenkinia paucispina West & West, x 750 (redrawn from Smith ) Golenkinia radiata (Chod.) Wille, x 750 (redrawn from Smith ) Acanthosphaera Zachariasi Lemmermann: 4, x 1000; 5, x 750 (redrawn from Smith ) Chlorochytrium Lemnae Cohn: 6, x about 250 (re- drawn from Bristol-Roach); 7, x 250 Kentrosphaera gloeophila (Bohlin) Brunnthaler, « 625 Characium ambiguum Hermann, x 500 Characium curvatum G. M. Smith, x 2000 (redrawn from Smith ) Characium falcatum Schroeder, x 700 Characium stipitatum (Bachm.) Wille, x 2000 (after Smith ) Characium gracilipes Lambert, x 1000 (redraw from Smith ) Characium Hookeri (Reinsch) Hansgirg, on Cyclops, < 500 Characium limneticum Lemmermann, x 1000 (re- drawn from Smith ) Characiopsis cylindrica (Lambert) Lemmermann, x 500 (redrawn from Smith) Characium obtusum A. Braun, x 1650 Characium Pringsheimii A. Braun, x 800 Characium rostratum Reinhard: 22, x 500; 23, x 750 [ 750 ] ga ga oa rs a 3 i xia cole leer lake 5| i jo} — | Co Fig. 14. Figs. 15, 16. Figs. 17, 18: Fig. 19. Fig. 20. PLATE 46 Chlorangium stentorinum (Ehrenb.) Stein, x 500 Coelastrum scabrum Reinsch, x about 1000 (redrawn from Bohlin ) Lagerheimia citriformis var. paucispina Tiffany & Ahl- strom, x about 1000 (redrawn from Tiflany & Ahl- strom ) Dispora crucigenioides Printz, x 700 Characium acuminatum A. Braun, x about 500 (re- drawn from Braun) Ankistrodesmus Braunii (Naeg.) Brunnthaler, x 500 Desmatractum bipyramidatum (Chod.) Pascher, x 1500 Selenastrum minutum (Naeg.) Collins, x 1200 Lagerheimia quadriseta (Lemm.) G. M. Smith, x 600 Eremosphaera oocystoides Prescott, x 1250 Characium operculum Ackley, x about 850 (redrawn from Ackley ) Characium ornithocephalum A. Braun, x 650 Excentrosphaera viridis Moore, x 500 Asterococcus spinosus Prescott: 17, x 800; 18, x 600 Characium Debaryanum (Reinsch) DeToni, x 320 Chlamydomonas mucicola Schmidle, x about 200 (re- drawn from Schmidle ) Figs. 21, 2la Tetraédron quadratum (Reinsch) Hansgirg: 21, x 800; Figs. 22, 23. Figs. 24, 25. Fig. 26. Fig. 27. 21a, x 400 Tetraédron duospinum Ackley Scenedesmus perforatus Lemmermann, x 1250 Stephanosphaera pluvialis Cohn, « 1000 Characium Rabenhorstii DeToni, « 750 [ 752 ] bo ed Q Co PLATE 47 Hydrodictyon reticulatum (L.) Lagerheim, x 75 Euastropsis Richteri (Schmidle) Lagerheim, = 1000 (after Smith ) Pediastrum araneosum var. rugulosum (G. S. West) G. M. Smith, x 590 Pediastrum araneosum (Racib.) G. M. Smith, x 590 (Reticulations on walls not shown.) Pediastrum biradiatum Meyen: 5, x 600; 6, x 300 Pediastrum biradiatum var. emarginatum fa. convexum Prescott, x 750 Pediastrum boryanum (Turp.) Meneghini, x 750 Pediastrum boryanum var. longicorne Raciborski, x 590 [ 754 ] ‘ enierrts fo a aio e if oy) can oe Neto e ote ‘ NGO Sores, rug aN womans »>wXy par AD . * mre Coir ARCH YS - ES a. ° apes Bee} igo ele hee ath , . etn. 87) Z tae Ne Sy eels 2k Seer ay er Jima poe 3 hee OF gars ane wath sees Gare ee ety OSes Wate z RIT Wage oe Leet Eri cn { SiGis, SAD oes Re Una Haaren pene aeay ERE rs Gita Ay, a ih tia a Ee “ NE Gia Sir} ih fiers. ae chic eran oa vf gists EET Cie Ris ty a e 5 oS fastest Bre ONE DE Docc RaynCe enn sigan fete EDN eB WAe oo Sy NOEs STA PRS COR Ne im al a a NN te foa om pa Airariaee Bi a eUh Races) Loni mete ey A eey 3) jh) : fies here Ns : 14) oN . Ae Ha neces . =X us raat Eon sen) Nasser a Na fies, Cisiiny eeu Caan ENON fiisicte I ae Bi ead wisn AR + Sh sey Ais Par USN alee : . Pat an om) oped Nets I kee: Rica t ease Fite) SERINE LES -~ X wehugie weiiatenig hiterses st west create ese) Beret APN AY SA Aiea dar Nene com ys i f + cre ‘ Miche nen gion» f oe ’ BBaes Sa Ete el schomu eens CaS ars ie Geran ee —N yo t “ a ———S+ Figs. 9, 10. Fig.l. Fig. 12. PLATE 48 Pediastrum Boryanum (Turp.) Meneghini, « 330 (re- drawn from Smith ) Pediastrum Boryanum var. undulatum Wille, « 500 Pediastrum Boryanum (Turp. ) Meneghini, « 500 Pediastrum duplex Meyen, x 500 (redrawn from Smith) Pediastrum Braunii Wartmann, < 750 Pediastrum duplex var. clathratum (A. Braun) Lager- heim, x 500 Pediastrum integrum var. priva Printz, x 666 (redrawn from Smith ) Pediastrum duplex var. rotundatum Lucks, x 333 (re- drawn from Smith ) Pediastrum integrum Naegeli: 9, x 330; 10, x 500 Pediastrum duplex var. cohaerens Bohlin, x 500 Pediastrum duplex var. gracilimum West & West, x 333 (after Smith ) [ 756 ] PLATE 49 Pediastrum duplex var. reticulatum Lagerheim, x 333 (after Smith) Pediastrum integrum var. scutum Raciborski, x 625 Pediastrum duplex var. rugulosum Raciborski, x 750 Pediastrum glanduliferum Bennett, x 1000 (redrawn from Bisley, ex West and Fritsch, courtesy Macmillan Publishing Co. ) Pediastrum sculptatum G. M. Smith, x 333 (after Smith) Pediastrum obtusum Lucks, x 590 Pediastrum muticum Kuetzing, x 750 Pediastrum muticum var. crenulatum Prescott, x 750 [ 758 } igene Fig. 2. Fig. 3. Figs. 4, 5. Fig. 6. Figiy: 1 OU rep Fig. 9. Fig. 10. PLATE 50 Pediastrum Kawraiskyi Schmidle, x 333 (after Smith ) Pediastrum simplex (Meyen) Lemmermann, x 500 Pediastrum tetras (Ehrenb.) Ralfs, x 1000 Pediastrum simplex var. duodenarium (Bailey) Raben- horst, x 500 Pediastrum tetras (Ehrenb.) Ralfs, x 1000 Pediastrum tetras var. tetraodon (Corda) Rabenhorst, x 1000 (redrawn from Smith) Sorastrum americanum (Bohlin) Schmidle, x 500 (re- drawn from Smith ) Sorastrum spinulosum Naegeli, x 750 (after Smith ) Sorastrum americanum var. undulatum G. M. Smith, x 750 (after Smith ) ( 760 | Figs. £52. Figs. 3, 4. Figs. 5-7. Fig. 8. Fig. 9. Fig. 10. Big, i. Fig. 12. Pigel3. Fig. 14. Fig. 15. PLATE 51 Echinosphaerella limnetica G. M. Smith, x 750 (after Smith ) Dictyosphaerium Ehrenbergianum Naegeli: 3, x 312; 4 x 37d Dictyosphaerium pulchellum Wood: 5 and 6, x 500; 7, details of cells and attaching strands, x 500 Treubaria setigerum (Archer) G. M. Smith, x 750 (re- drawn from Smith ? Oocystis crassa Wittrock, x 1000 (redrawn from Smith) Oocystis Borgei Snow, x 750 Oocystis elliptica W. West, x 600 Oocystis Eremosphaeria G. M. Smith, x 590 Oocystis gloeocystiformis Borge, x 350 Oocystis gigas Archer, x 500 Oocystis pusilla Hansgirg, x 1000 (after Smith ) [ 762 ] figs.i6, 7, Fig. 8. Figs. 9, 10. Eig; PLATE 52 Botryococcus Braunii Kuetzing, x 875 (redrawn from Blackburn ) Botryococcus sudeticus Lemmermann, x 600 (redrawn from Smith ) Botryococcus protuberans var. minor G. M. Smith: 4, x 750; 5, x 1500 (redrawn from Smith) Tetraédron enorme ( Ralfs) Hansgirg fa., x 885 Trochiscia obtusa (Reinsch) Hansgirg, x 750 Gloeocystis major Gerneck: 9, x 750; 10, x 560 Botryococcus Braunii Kuetzing, x 600 (after Smith ) [ 764 ] Figg. Fig. 2, Fig. 3. Figs. 4, 5. Fig. 6. Fig. 7. Fig. 8. Fig, 9. Fig. 10. Figs. 11, 12. Fig. 13. Fig. 14. Figs. 15, 16. Bical 7. Fig. 18. Figs. 19, 20. Biga2t, Fig. 22. Fig. 23. PEATE 53 Sorastrum spinulosum N aegeli, x 590 Coelastrum cambricum Archer, x 412 (redrawn from Smith ) Coelastrum microporum Naegeli, x 350 Coelastrum proboscideum Bohlin: 4, x 825 (redrawn from Smith ); 5, x 650 Coelastrum reticulatum (Dang.) Senn, x 500 Coelastrum sphaericum Naegeli, x 237 (adapted from West and Fritsch, courtesy Macmillan Publishing Co.) Coelastrum proboscideum Bohlin, x 825 (redrawn from Smith ) Zoochlorella parasitica Brandt: cells in Ophrydium, x 500; enlarged cells, x 1000 Zoochlorella conductrix Brandt: cells within tentacles of Hydra, x 100; enlarged cells, x 590 Chlorella ellipsoidea Gerneck: x 225; 12, x 650 Chlorella vulgaris Beyerinck, x 1000 (redrawn from Smith ) Westella botryoides (W. West) de Wildemann, x 650 Westella linearis G. M. Smith, x 500 (after Smith) ‘Trochiscia aspera (Reinsch) Hansgirg, x 850 Trochiscia granulata (Reinsch) Hansgirg, « 590 Trochiscia reticularis (Reinsch) Hansgirg: 19, x 800; 20, x 1000 (redrawn from Smith ) Trochiscia Zachariasii Lemmermann, * 1000 Eremosphaera viridis DeBary, x 50 Planktosphaeria gelatinosa G. M. Smith, x 250 [ 766 ] Bigs, 6:./. Figs. 8, 9. Fig. 10. Fig. 11. Fig. 12. Figs. 13, 14. Figs. 15, 16. Fig. 17. Fig. 18. Fig. 19. Fig. 20. PLATE 54 Oocystis lacustris Chodat, x 1750 Oocystis natans var. major G. M. Smith, x 1000 Oocystis parva West & West, x 750 Oocystis pusilla Hansgirg: 4, colony, x 800; 5, single cell, « 1350 Oocystis nodulosa West & West: 6, x 250; 7, x 400 (adapted from West, ex Brunnthaler ) Oocystis pyriformis Prescott, x 590 Oocystis solitaria Wittrock, x 1000 Oocystis panduriformis var. minor G. M. Smith, x 1000 Oocystis submarina Lagerheim, x 1000 (redrawn from Smith ) Gloeotaenium Loitelsbergerianum Hansgirg, x 440 Nephrocytium Agardhianum Naegeli, x 500 Nephrocytium ecdysiscepanum W. West, x 500 Nephrocytium limneticum (G. M. Smith) G. M. Smith, x 500 Nephrocytium lunatum W. West, x 750 Nephrocytium obesum West & West, x 590 | 768 J bo He O09 PLATE 55 Lagerheimia ciliata (Lag.) Chodat, x 100 (redrawn from Smith ) Lagerheimia ciliata var. minor (G. M. Smith) G. M. Smith, x 1000 (redrawn from Smith ) Ankistrodesmus convolutus Corda, x 1000 Lagerheimia citriformis (Snow) G. M. Smith, x 1000 (re- drawn from Smith ) Lagerheimia longiseta (Lemm.) Printz, x 1000 (redrawn from Smith ) Lagerheimia longiseta var. major G. M. Smith, x 1000 (re- drawn from Smith ) Lagerheimia subsalsa Lemmermann, x 1000 (redrawn trom Smith ) Dimorphococcus lunatus A. Braun, x 750 | 770 ] Fig. 10. Figs. 11, 12. Fig. 13. Figs. 14, 15. Fig. 16. PLATE 56 Franceia Droescheri (Lemm.) G. M. Smith, x 900 (re- drawn from Smith ) Franceia ovalis (Francé) Lemmermann, x 1000 (re- drawn from Smith ) Ankistrodesmus falcatus (Corda) Ralfs, x 500 Ankistrodesmus fractus (West & West) Brunnthaler, x 700 Cerasterias staurastroides West & West, « 590 Ankistrodesmus falcatus var. tumidus (West & West) G. S. West, x 1000 (after Smith ) Ankistrodesmus falcatus var. mirabilis (West & West ) G. S. West, x 1000 (after Smith ) Ankistrodesmus spiralis (Turner) Lemmermann, x 1000 (after Smith ) Dactylococcus infusionum Naegeli, x 735 (redrawn from Smith ) Ankistrodesmus falcatus var. stipitatus (Chod.) Lem- mermann, x 590 Ankistrodesmus falcatus var. acicularis (A. Braun) G. S. West, x 1000 (redrawn from G. S. West) PrATE yo” Figeel: Closteriopsis longissima Lemmermann, x 300 Figs. 2,3. Closteriopsis longissima var. tropica West & West: 2, x 220; 3, x 400 (after Smith) Fig. 4. Schroederia setigera (Schroed.) Lemmermann, x 1000 (after Smith ) Figs. 5,6. Schroederia Judayi G. M. Smith: 5, x 1000 (after Smith); 6, x 1500 Figs. 7,8. Kirchneriella contorta (Schmidle) Bohlin: 7, x 650; 8, x 1000 Fig. 9. Selenastrum Bibraianum Reinsch, x 1000 (redrawn from Smith ) Fig. 10. Selenastrum Westii G. M. Smith, x 1000 (redrawn from Smith ) Fig. 11. Selenastrum gracile Reinsch, x 1000 (redrawn from Smith ) Big: Kirchneriella obesa var. major (Bernard) G. M. Smith, x 500 [774 ] PLATE 58 Fig. 1. Kirchneriella elongata G. M. Smith, x 1000 (redrawn from Smith ) Fig. 2. Kirchneriella lunaris ( Kirch.) Moebius, x 500 Fig. 3. Kirchneriella lunaris var. Dianae Bohlin, x 500 Fig. 4. Kirchneriella lunaris var. irregularis G. M. Smith, x 1000 (redrawn from Smith ) Fig. 5. Kirchneriella obesa (W. West) Schmidle, « 500 Figs.6,7. | Kirchneriella obesa var. aperta (Teil.) Brunnthaler: 6, x 600; 7, x 700 Fig. 8. Kirchneriella subsolitaria G. S. West, x 650 Figs.9,10. Quadrigula closterioides (Bohlin) Printz: 9, x 600; 10, x 500 [ 776 ] ee Figs. 1-3. Figs. 4, 5. Figs. 6, 7. Fig. 8. Figs. 9, 10. Figs. 11-13. Fig. 14. Figs. 15, 16. Fig. 17. igs 13: Fig. 19. Figs. 20-22. Fig. 23. Figs. 24, 25. Fig. 26. Fig. 27. Fig. 28. PLATE 59 Quadrigula Chodatii (Tanner-Fullman) G. M. Smith: 1, x 500 (redrawn from Smith); 2, x 590; 3, x 500 Quadrigula lacustris (Chod.) G. M. Smith, x 500 (after Smith ) Tetraédron armatum (Reinsch ) DeToni, x 400 Tetraédron arthrodesmiforme (W. West) Wolszyn- ska, x 175 (redrawn from Tiffany ) Tetraédron arthrodesmiforme var. contorta Wotoszyn- ska, x 1000 Tetraédron asymmetricum Prescott, x 500 Tetraédron bifurcatum (Wille) Lagerheim, x 500 Tetraédron bifurcatum var. minor Prescott: 15, x 500; 16, x 750 Tetraédron caudatum (Corda) Hansgirg, x 200 Tetraédron enorme var. pentaedricum Prescott, x 650 Tetraédron enorme (Ralfs) Hansgirg, x 650 Tetraédron caudatum var. longispinum Lemmermann, < 1000 (redrawn from Smith) Tetraédron cruciatum var. reductum Prescott, x 600 Tetraédron caudatum (Corda) Hansgirg, x 1000 (af- ter Smith ) Tetraédron hastatum (Reinsch) Hansgirg, x 100 (after Smith ) Tetraédron hastatum var. palatinum (Schmidle) Lem- mermann, x 1000 (after Smith) Tetraédron constrictum G. M. Smith, x 1000 (after Smith ) [ 778 ] Fig. 8. Figs. 9, 10. Fig. 11. Figs. 12-15. Figs. 16, 17. Fig. 18. PLATE 60 Tetraédron gracile (Reinsch) Hansgirg, x 1000 (after Smith ) Tetraédron limneticum Borge: 2-3, x 590; 4, x 1000 Tetraédron limneticum var. gracile Prescott, x 590 Tetraédron lobulatum (Naeg.) Hansgirg, x 1000 (after Smith ) Tetraédron lobulatum var. crassum Prescott, x 1000 Tetraédron lunula (Reinsch) Wille, x 1000 Tetraédron lobulatum var. polyfurcatum G. M. Smith, < 1000 (after Smith ) Tetraédron minimum (A. Braun) Hansgirg, x 1000 (14 and 15, after Smith) Tetraédron muticum (A. Braun) Hansgirg: 16, x 1000; 17, x 590 Tetraédron muticum fa. punctulatum (Reinsch) De- Toni, x 1000 (after Smith) Tetraédron obesum (West & West) Wille: 19, x 600; 20, x 650 Tetraédron pentaedricum West & West, x 1000 (23, after Smith) Tetraédron regulare Kuetzing, x 1000 (26, after Smith) Tetraédron planctonicum G. M. Smith, x 1500 Tetraédron pusillum (Wallich) West & West, x 1750 (redrawn from Turner, ex Brunnthaler ) [ 780 } Fig Figs. 2, 3. Figs. 4-7. Figs. 8-10. Pigs iL 12, Fig. 18. Figs. 14-16. Figs 17,18: Figs. 19, 20. Fig. 21. Figs. 22, 23, Figs. 24, 25. Figs. 26, 27. Figs. 28, 29. PLATE 61 Tetraédron regulare var. bifurcatum Wille, x 500 Tetraédron regulare var. granulata Prescott, x 500 Tetraédron regulare var. incus Teiling, x 500 (6 and 7, after Smith ) Tetraédron regulare var. torsum (Turner) Brunntha- ler: 8 and 9, x 500 (after Smith); 10, x 1000 Tetraédron trigonum (Naeg.) Hansgirg, x 500 Tetraédron regulare var. incus fa. major Prescott, 2500 Tetraédron trigonum var. gracile (Reinsch) DeToni, x 1000 Tetraédron tumidulum (Reinsch) Hansgirg, x 1000 Cerasterias staurastroides West & West: 19, x 2500; 20, x 4000 Scenedesmus abundans (Kirch.) Chodat, x 500 (after Smith ) Scenedesmus abundans var. asymmetrica (Schroed. ) G. M. Smith, x 500 (after Smith) Tetraédron verrucosum G. M. Smith, x 500 (after Smith ) Scenedesmus abundans var. brevicauda G. M. Smith, x 500 (redrawn from Smith ) Tetraédron Victorieae var. major G. M. Smith, x 500 (after Smith ) [ 782 ] Fig, Figs. 2, 3. Figs. 4, 5. igs 10a. Fig. 8. Fig. 9. Figs. 10-12. Figs. 13, 14. Fig, 15, Fig. 16. PLATE 62 Scenedesmus abundans var. breviccuda G. M. Smith, iy Ww A 4 (yy) AAW ’ ND ' if my NY { WY S) \) ' 7 Xi a Xs SY Rh) SM) SS we | \ WIA y SAX WY i Wi tht Wy Ua) Wy mi rh WZ a SS PLATE 81 Bigeall Chara Braunii Gmelin, x 65 Figs. 2-6. | Chara canescens Loiseleur-Deslongchamps: 2, portion of plant, x 1; 3 and 4, apices of branchlets, x 50; 5, node, x 15; 6, oogonium, x 25 Figs. 7-10. Chara excelsa Allen: 7, cortications, x 20; 8, nodes of cortical cells, x 40; 9, apex of branchlet, x 47; 10, oogonium, x 40 [ 822 ] PLATE 82 Figs. 1-5. Chara vulgaris Linnaeus: 1, portion of plant, x 12°2; apex of branchlets, x 31; 3 and 4. node, x 12; 5, oogonium, x 16 Figs. 6-8. Chara fragilis Desvaux: 6, apex of branchlet, x 18; 7, sex organs, x 14; 8, node, x 14 Figs. 9-12. Chara sejuncta A. Braun: 9, portion of fertile branch- let, x 13; 10, apex of branchlet, x 14; 11, node, x 19; 12, portion of axis showing cortical and spine cells, ein Figs. 13-15. Chara elegans (A. Braun) Robinson: 13, sex organs, x 50; 14, apex of branchlet, x 50; 15, node, x 22 [ 824 ] Wy " Wi VN i) \\ Se hy ‘NY I \ ll iS s i al aL “wy if . WHE WW, we Bien: Figs. 2, 3. Figs. 4, 5. Fig. 6. Wigs: 7,8: Fig. 9. Fig. 10. Fig i. Fig. 12. Fig. 13. Figs. 14, 15. Figs. 16, 17. Figs. 18, 19. Fig. 20. Fig. 21. Figs. 22, 23. Figs. 24, 25. Fig. 26. Fig. 27. Fig. 28. Fig. 29. Fig. 30. Papo: Fig. 32. Fig. 33. Fig. 34. Fig. 35. PLatTe 83 Trachelomonas volvocina Ehrenberg, x 938 Trachelomonas volvocina var. compressa Drezepolski: 2150023, x 1125 Trachelomonas varians (Lemm.) Deflandre, x 885 Trachelomonas triangularis Deflandre, « 1500 Trachelomonas volvocina Ehrenberg fa., x 750 Trachelomonas rotunda Swirenko, x 885 Trachelomonas intermedia Dangeard, x 885 Trachelomonas cylindrica Ehrenberg, x 885 Trachelomonas volvocina var. punctata Playfair, x 1500 Trachelomonas acanthostoma (Stokes) Deflandre, x 885 Trachelomonas lacustris Drezepolski, x 938 Trachelomonas Kelloggii (Skv.) Deflandre, x 885 Trachelomonas abrupta (Swir.) Deflandre, x 885 Trachelomonas cylindrica Ehrenberg, x 885 Trachelomonas Dybowskii Drezepolski, x 1500 Trachelomonas pulcherrima Playfair, x 885 Trachelomonas pulcherrima var. minor Playfair, x 1050 Trachelomonas armata var. Steinii Lemmermann, x DES) Trachelomonas armata var. longispina (Playf.) De- flandre, x 975 Trachelomonas pulchella Drezepolski, x 975 Trachelomonas robusta Swirenko, « 1125 Trachelomonas hispida var. coronata Lemmermann, x 885 Trachelomonas hispida var. crenulatocollis fa. recta Deflandre, « 900 Trachelomonas armata (Ehrenb.) Stein, x 1125 Trachelomonas armata fa. inevoluta Deflandre, x 900 Trachelomonas superba var. Swirenkiana Deflandre, x 900 Trachelomonas hispida (Perty ) Stein, x 885 [| 826 ] Fig g. Fig. Figs. 3, 4. lEs D) Fig. Fig. 6. Fig. 7. Figs. 8, 9. ga’ ga gq aa ga Q oO i comes Q S: oe OF ie 12. PLATE 84 Trachelomonas horrida Palmer, x 1125 Trachelomonas sydneyensis Playfair, x 885 Trachelomonas hispida var. punctata Lemmermann, x 885 Trachelomonas superba var. spinosa Prescott, x 1125 Trachelomonas Dybowskii Drezepolski, x 750 Trachelomonas hispida var. papillata Skvortzow, x 975 Trachelomonas superba var. Swirenkiana Deflandre: §, ~ 9a 91050 Trachelomonas superba (Swir.) Deflandre, x 1125 Trachelomonas superba var. duplex Deflandre, x 1125 Trachelomonas similis Stokes, x 1500 Trachelomonas speciosa Deflandre, x 885 Trachelomonas Girardiana (Playf.) Deflandre, x 885 Trachelomonas bulla (Stein) Deflandre, « 885 Trachelomonas hexangulata var. repanda Prescott, x 885 Trachelomonas crebea var. brevicollaris Prescott, x 1125 [ 828 ] PLATE 85 Figs. 1, 2. Trachelomonas dubia (Swir.) Deflandre, « 885 Fig. 3. Trachelomonas acanthostoma (Stokes) Deflandre, x 125 Fig. 4. Trachelomonas aculeata fa. brevispinosa Prescott, x 750 Figs. 5, 6. Trachelomonas hexangulata Swirenko, x 885 Figs/(. Trachelomonas scabra var. longicollis Playfair, x 1125 Figs. 8, 9. Trachelomonas Playfairii Deflandre, x 885 Fig. 10. Trachelomonas similis Stokes, x 1500 Big. 1. Trachelomonas hexangulata Swirenko fa., « 885 Fig. 12. Trachelomonas mammillosa Prescott, « 900 Fig. 18. Trachelomonas similis Stokes, x 1200 Fig. 14. Trachelomonas charkowiensis Swirenko, x 1050 Fig. 15. Trachelomonas lacustris Drezepolski, « 885 Fig. 16. Trachelomonas erecta Skvortzow, x 900 Fig. 17. Euglena gracilis Klebs, x 750 Fig. 18. Euglena oxyuris var. minor Prescott, x 750 Fig. 19. Trachelomonas spectabilis Deflandre, « 885 Fig. 20. Euglena deses Ehrenberg, x 195 Figs. 21,22. Euglena polymorpha Dangeard, = 450 Figs. 23,24. Euglena minuta Prescott, x 885 Fig. 25. Euglena proxima Dangeard, = 885 Fig. 26. Phacus pseudoswirenkoi Prescott, x 975 Fig. 27. Euglena acus var. rigida Huebner, x 900 Fig. 28. Euglena acus Ehrenberg, x 885 [ 830 ] PLATE 86 igss 2: Euglena sanguinea Ehrenberg, x 750 Fig, 3. Euglena elongata Schewiakoff, x 1200 Figs. 4-6. Euglena tripteris (Duj.) Klebs: 4 and 5, = 885; 6, x 1200 Figs. 7-9. Euglena convoluta Korshikov, x 885 Figs. 10-12. Euglena elastica Prescott, x 975 Fig. 13. Euglena Ehrenbergii Klebs, x 375 Fig. 14. Euglena convoluta Korshikov, paramylon bodies Fig. 15. Euglena Spirogyra Ehrenberg, x 885 [ 882 ] Riged, Fig. 2. Fig. 3. Figs. 4-6. Figs: 1,0. Fig. 9. Fig. 10. Rig ar Fig. 12. Fig. 13. Fig. 14. Figs. 15, 16. PLATE 87 Phacus longicauda (Ehrenb.) Dujardin, « 750 Phacus pseudoswirenkoi Prescott, x 975 Phacus anacoelus var. undulata Skvortzow, x 675 Phacus Spirogyra var. maxima Prescott: 4, x 675; 5 and 6, x 750 Phacus anacoelus Stokes: 7, x 1125; 8, apical view Phacus helikoides Pochmann, x 750 Phacus orbicularis Huebner, x 750 Phacus Birgei Prescott, x 750 Phacus orbicularis var. caudatus Skvortzow, x 900 Phacus caudatus Huebner, x 885 Phacus curvicauda Swirenko, x 900 Phacus chloroplastes Prescott, x 900 [ 834 } ig. Je Figs. 2, 3. Fig. 4. Figs. 5-8. Fig. 9. Paget; Faget Fig. 12. Fig. 13. Fig. 14. Fig. 15. Fig. 16. Figs: 7518; Rigg: Fig. 20. ag. 2, Pig. 22. Fig. 23. Fig. 24. PLaTE 88 Phacus Nordstedtii Lemmermann, x 885 Phacus suecicus Lemmermann, x 900 Phacus acuminatus Stokes, x 885 Phacus chloroplastes fa. incisa Prescott, « 900 Phacus crenulata Prescott, « 1125 Phacus orbicularis var. Zmudae Namyslowski, « 1125 Phacus anacoelus Stokes, x 885 Phacus Lemmermannii (Swir.) Skvortzow, x 900 Phacus caudata var. ovalis Drezepolski, x 900 Phacus pseudoswirenkoi Prescott, x 1050 Phacus orbicularis var. caudatus Skvortzow, x 900 Phacus pleuronectes (Muell.) Dujardin, « 885 Phacus acuminatus var. Drezepolskii Skvortzow, = 885 Phacus asymmetrica Prescott, x 1500 Phacus tortus (Lemm.) Skvortzow, = 885 Phacus curvicauda Swirenko, x 1050 Phacus pyrum (Ehrenb. ) Stein, x 750 Phacus Segretii var. ovum Prescott, x 900 Phacus Swirenkoi Skvortzow, x 1125 [ 836 ] Figs. 1-4. Figs. 5, 6. Fig. 7. Figs. 8, 9. Fig. 10. Figs. 11-13. Fig. 14. Fig. 15. Fig. 16. Pica li, Figs. 18, 19. Fig. 20. Fig. 21. Fig. 22. Fig. 23. PLATE 89 Lepocinclis fusiformis (Carter ) Lemmermann, x 900 Lepocinclis ovum (Ehrenb.) Lemmermann, x 885 Lepocinclis fusiformis var. major Fritsch & Rich, x 900 Lepocinclis acuta Prescott, x 1050 Lepocinclis glabra ta. minor Prescott, x 900 Lepocinclis Sphagnophila Lemmermann, x 1050 Lepocinclis glabra Drezepolski, x 750 Lepocinclis fusiformis var. major Fritsch & Rich, x 900 Lepocinclis Playfairiana Deflandre, = 900 Trachelomonas granulosa Playfair, x 885 Colacium vesiculosum Ehrenberg, x 585 Phacus anacoelus var. undulata fa. major Prescott, x 1050 Trachelomonas euchlora (Ehrenb.) Lemmermann, x 750 Colacium arbuscula Stein, x 885 Gymnodinium fuscum (Ehrenb.) Stein, x 675 [ 838 ] Figs. 1-3. Figs. 4-6. Fig. 7. Figs. 8, 9. Figs. 10, 11. Figs. 12-14. Figs, lo; 16: Figs. 17, 18. Figs. 19, 20. Fig. 21. Figs. 22-24. Figs. 25, 26. Figs. 27-29. PLATE 90 Gymnodium caudatum Prescott: 1 and 2, x 700; 3, x 600 Hemidinium nasutum Stein: 4 and 5, x 560; 6, x 1000 Glenodinium armatum Levander, x 700 Glenodinium Borgei (Lemm.) Schiller, x 700 Glenodinium Gymnodinium Penard: 10, x 700; 11, x about 700 (redrawn from Wotoszynska ) Glenodinium Kulczynskii (Wotosz.) Schiller, x 590 Glenodinium palustre (Lemm. ) Schiller, x 1000 Glenodinium pulvisculus (Ehrenb.) Stein, x 750 Glenodinium quadridens (Stein) Schiller, x 600 Glenodinium Penardiforme (Linde. ) Schiller, x 750 Peridinium inconspicuum Lemmermann, x 590 Peridinium gatunense Nygaard: 25, « 350; 26, x 500 Dinoflagellate cysts, x 500 [ 840 ] Figs. Figs. Figs. Figs. Figs. Figs. Figs. PLATE 91 Peridinium cinctum (Muell.) Ehrenberg, x 600 Cystodinium cornifax (Schill.) Klebs, x 300 Peridinium cinctum var. tuberosum (Meunier ) Linde- man: 7, x 600; 8-10 (after Meunier, ex Schiller), x about 188; 1] and 12, x 600 Peridinium wisconsinense Eddy: 13 and 15, x 500; 14, x 250 Peridinium limbatum (Stokes ) Lemmermann, x 750 Cystodinium iners Geitler: 19, x 750; 20 and 21, x 325 (21 redrawn from Geitler ) Peridinium Willei Huitfeld-Kaas: 22, x 600; 23 and 24, x 440; 25, x 600 [ 842 | ig Figs. 2, 3. Figs. 4, 5. Figs. 6; 7. Figs. 8, 9. PLATE 92 Synura Adamsii G. M. Smith, x 590 Ceratium carolinianum (Bailey ) Jorgensen, x 500 Ceratium hirundinella (O. F. Muell.) Dujardin: 4, cyst, x 590; 5, x 1000 Synura uvella Ehrenberg: 6, x 1250; 7, x 500 Ceratium cornutum (Ehrenb.) Claparéde & Lachmann, x 500 [ 844 ] Figs. 1, 2. Fig. 3. Figs. 4-7. Figs. 8-10. Figs. 11-13. Figs. 14, 15. Figs. 16-19. Figs. 20-22. Figs. 23-25. Figs. 26, 27. Figs. 28, 29. Fig. 30. Bigsot. Fig. 32. Figs. 33, 34. Figs. 35, 36. PLATE 93 Cystodinium Steinii Klebs, x 500 Tetradinium javanicum Klebs, x 500 Raciborskia bicornis Woloszynska, x 600 Chlorochromonas minuta Lewis, x 1500 (redrawn from Smith ) Stipitococcus apiculatus Prescott: 11 and 12, x 600; 13, x 2000 Stipitococcus capense Prescott, x 590 Stipitococcus crassistipatus Prescott, x 1000 Stipitococcus urceolatus West & West, x 2000 Harpochytrium Hyalothecae Lagerheim, x 590 Chlorobotrys regularis (W. West) Bohlin, x 590 Centritractus dubius Printz, x 1000 Mischococcus confervicola Naegeli, x 590 Characiopsis lageniformis Pascher, x 750 Characiopsis longipes (Rab.) Borzi, x 1000 Characiopsis pyriformis (A. Braun) Borzi, x 590 Gloeobotrys limneticus (G. M. Smith) Pascher, x 590 [ 846 ] Migs 1 2: Figs. 3-5. Fig. 6. Figs. 7-9. Figs. 10, 11. Fig. 12. Figs. 13, 14. Fug: Lo. Fig. 16. Figs. 17, 18. Fig. 19. Fig. 20. Figs. 21, 22. Fig, 23. PLaTE 94 Characiopsis cylindrica (Lambert) Lemmermann, x 590 Characiopsis spinifer Printz, x 590 Peroniella Hyalothecae Gobi, x 590 Peroniella planctonica G. M. Smith, x 1000 (9, redrawn from Smith ) Ophiocytium cochleare (Eichw.) A. Braun, x 590 Ophiocytium arbuscula (A. Braun) Rabenhorst, « 590 Ophiocytium elongatum var. major Prescott, x 590 Ophiocytium cochleare (Eichw.) A. Braun, x 600 Ophiocytium mucronatum (A. Braun) Rabenhorst, x 590 Ophiocytium majus Naegeli: 6, x 400; 7, x 590 Ophiocytium capitatum var. longispinum (Moebius) Lemmermann, x 1000 (after Smith ) Ophiocytium parvulum (Perty) A. Braun, x 1000 (re- drawn from Smith ) Ophiocytium capitatum Wolle, x 590 Ophiocytium bicuspidatum (Borge) Lemmermann, x 400 [ 848 ] Figs. 1-3. Fig. 4. Fig. 5. Figs. 6-8. Figs. 9, 10. Big. e Figs. 12, 13. Fig. 14. Figs 15, Figs. 16—18. Figs. 19, 20. Figs. 21, 22. Fig. 23. Fig, 24. Figs. 25, 26. Figs. 27, 28. Figs. 29-31. Figs. 32, 33. Fig. 34. Figs. 35, 36. Figs. 37, 38. Fig. 39. Fig. 40. Fig. 41. Fig. 42. Figs. 43, 44. Fig. 45. PLATE 95 Goniochloris sculpta Geitler, x 1000 Chlorallanthus oblongus Pascher, x 1500 Trachychloron biconicum Pascher, x 1500 Bumilleriopsis brevis Printz, x 1500 Arachnochloris minor Pascher, x 1500 Chlorothecium Pirottae Borzi, « 1500 Tetragoniella gigas Pascher, x 550 Diachros simplex Pascher, x 625 Pleurogaster lunaris Pascher, x 500 Chlorellidiopsis separabilis Pascher, x 1000 Pleurogaster oocystoides Prescott, x 1000 Meringosphaera spinosa Prescott, « 800 Chlorellidiopsis separabilis Pascher, x 1000 Monallantus brevicylindrus Pascher, x 1000 Perone dimorpha Pascher, x 1000 (26, redrawn from Pascher ) Botrydiopsis arhiza Borzi: 27, x 500, 28, x 1500 Characiopsis acuta (A. Braun) Borzi, x 1000 Stipitococcus vasiformis Tiffany, x 1000 Derepyxis dispar (Stokes ) Senn, x 1000 Ophiocytium gracilipes (A. Braun) Rabenhorst, x Centritractus belanophorus Lemmermann, x 500 Cryptomonas erosa Ehrenberg, x 1000 Cryptomonas ovata Ehrenberg, x 1000 Chrysostephanosphaera globulifera Scherftel, x 400 Chlorochloster pyreniger Pascher, x 625 Trachychloron depauperatum Pascher, x 1500 Chroomonas Nordstedtii Hansgirg, x 1000 [ 850 | Bigel: Figs. 2, 3. Figs. 4, 5. Fig. 6. Figs. 7-9. Fig. 10. Fig. 11. Figs. 12, 13. Figs. 14-16. Figs. 17, 18. Fig. 19. DA), ee wo wo Ww bw me 09 LO PLATE 96 Phaeothamnion confervicola Lagerheim, x 590 Ophiocytium desertum var. minor Prescott, x 590 Ophiocytium parvulum (Perty) A. Braun, x 590 Bumilleria sicula Borzi, x 590 Tribonema affine G. S. West, x 500 Tribonema bombycinum (C. A. Ag.) Derbés & Solier, x 600 Tribonema bombycinum var. tenue Hazen, x 750 Tribonema minus (Wille) Hazen: 12, x 590; 13, x 1000 Tribonema utriculosum (Kuetz.) Hazen: 14 and 15, x 590; 16, x 800 Botrydium granulatum (L.) Greville: 17, x 18; 18, x 4 Mallomonas alpina Pascher & Ruttner, x 500 Mallomonas acaroides var. Moskovensis (Wermel) Krieger, x 590 Derepyxis amphora Stokes, x 700 Mallomonas acaroides Perty, x 750 Mallomonas pseudocoronata Prescott, x 500 Mallomonas elliptica (Kisselew ) Conrad, x 500 [ 852 ] PLATE 97 igs. Mallomonas caudata Iwanoff, x 590 Fig, 2. Mallomonas fastigata var. macrolepis (Conrad) Con- rad, x 750 | Fig. 3. Mallomonas apochromatica Conrad, x 590 Fig. 4. Mallomonas producta (Zacharias ) Iwanoff, x 500 (re- drawn from Smith ) Fig. 5. Mallomonas producta var. Marchica Lemmermann, x 500 (redrawn from Smith ) Fig. 6. Mallomonas tonsurata Teiling, x 500 (redrawn from Smith ) Fig. 7. Mallomonas urnaformis Prescott, x 1000 Fig. 8. Chrysostrella paradoxa Chodat, x 800 Fig. 9. Lagynion ampullaceum (Stokes ) Pascher, x 600 Fig. 10. Lagynion macrotrachelum (Stokes ) Pascher, x 1000 Big TT: Lagynion triangularis var. pyramidatum Prescott, x 1000 Figs. 12,18. Lagynion reductum Prescott: 12, x 590; 13, x 1000 Fig. 14. Lagynion Scherffelii Pascher, x 600 [ 854 ] PLATE 98 Chrysosphaerella longispina Lauterborn, x 700 Rhizochrysis limnetica G. M. Smith, x 400 (redrawn from Smith ) Dinobryon Tabellariae (Lemm.) Pascher, x 1000 (re- drawn from Smith) Dinobryon bavaricum Imhof, x 700 Dinobryon divergens Imhof, x 750 Dinobryon calciformis Bachmann, x 1000 (after Smith) Dinobryon sertularia Ehrenberg, 500 Hyalobryon mucicola (Lemm.) Pascher, x 1000 Dinobryon sociale Ehrenberg, x 750 {| 856 | PLATE 99 Figs. 1-5. Uroglenopsis americana (Calkins) Lemmermann, x 1000 (3-5 after Smith ) Fig. 6. Chrysamoeba radians Klebs, x 1000 (after Smith) PigaT. Chrysidiastrum catenatum Lauterborn, x 500 (after Smith ) Fig. 8. Chrysocapsa planctonica (West & West) Pascher, 1000 (after Smith ) Figs.9,10. | Phaeothamnion confervicola Lagerheim, x 500 Figs. 11,12. Gonyostomum semen (Ehrenb. ) Diesing, x 500 [ 858 ] Figs, 1-3. Figs. 4, 5. Fig. 6. Fig. Figae: Fig. 9. be Fig. 10. lid al. als: 14, » Ld: BAG), Towle g. 18. g. 19. PLATE 100 Chroococcus dispersus var. minor G. M. Smith, x 825 (redrawn from Smith) Chroococcus limneticus Lemmermann, x 500 Chroococcus limneticus var. carneus (Chod.) Lemmer- mann, x 310 Chroococcus dispersus (Keiss].) Lemmermann, x 825 Chroococcus limneticus var. distans G. M. Smith, x 750 Chroococcus minutus (Kuetz.) Naegeli, x 600 Chroococcus limneticus var. subsalsus Lemmermann, x 825 (redrawn from Smith) Chroococcus limneticus var. elegans G. M. Smith, x 825 (redrawn from Smith ) Chroococcus minor (Kuetz.) Naegeli, x 590 Chroococcus Prescottii Drouet & Daily, x 600 Chroococcus pallidus Naegeli, x 590 Chrooceccus varius A. Braun, x 1000 Chroococcus giganteus W. West, x 825 (redrawn from Smith ) M erismopedia tenuissima Lemmermann, x 1250 Merismopedia elegans var. major G. M. Smith, x 500 Chroococcus turgidus (Kuetz.) Naegeli. x 590 [ 860 | \O@080, © Ode: OO0o°. 19 = PLATE 101 Figs. Merismopedia elegans A. Braun, x 500 Figs, 2-4. Merismopedia glauca (Ehrenb.) Naegeli: 2, x 590; 3, x 600; 4, x 590 Fig. 5. Merismopedia Trolleri Bachmann, x 1000 Fig. 6. Gloeocapsa aeruginosa (Carm.) Kuetzing, x 750 Lae fe Gloeocapsa punctata Naegeli, x 750 Figs. 8, 9. Aphanocapsa delicatissima West & West: 8, x 900; 9, x 1000 Figs. 10,11. Aphanocapsa elachista var. conferta West & West, x 750 Fig. 12. Aphanocapsa elachista var. planctonica G. M. Smith, x 500 Fig. 13. Aphanocapsa endophytica G. M. Smith, x 1000 (re- drawn from Smith) Fig. 14. Aphanocapsa pulchra (Kuetz.) Rabenhorst, x 500 Figs. 15,16. Aphanocapsa Grevillei (Hass.) Rabenhorst, 500 Fig. 17. Aphanocapsa rivularis (Carm.) Rabenhorst, x 825 (re- drawn from Smith ) [ 862 | Oo: ° o) © (a) SS Se, ean eeees® OOOO OO ‘GO OO 1? i H H — tans 20 fou too) So fo) (ee) % fo} & © a 22 ie) oe Oo tee PB Qc 390 9 (ome) ee) (o) fe} on @) iow ° 008 pees! ED © Qua tho ; ee US PeB) a ° i ie ch Sears) 16 3°99 : a @ 20°6, go oe Be ae, PLATE 102 Figs. 1-3. Microcystis aeruginosa Kuetz.; emend. Elenkin: 1, x 170; 2, x 1500; 3, x 940 Fig. 4. Microcystis aeruginosa Kuetz.; emend. Elenkin: unper- forated colony (M. flos-aquae ), x 750 Fig. 5. Microcystis incerta Lemmermann, x 750 Figs. 6-8. Synechococcus aeruginosus Naegeli, x 940 Fig. 9. Glocothece linearis Naegeli, x 750 Fig. 10. Merismopedia punctata Meyen, x 750 [ 864 ] Rigel Figs. 2,3: Fig. 4. Figs. 5, 6. Figs. 7, 8. Figs. 9, 10. Figs. 11, 12. Fig, 13. Figs. 14-16. PLATE 103 Gloeothece linearis var. composita G. M. Smith, x 750 Gloeothece rupestris (Lyngb.) Bornet, x 750 Rhabdoderma Gorskii Woloszynska, x 750 Rhabdoderma sigmoidea fa. minor Moore & Carter: 5, 7100s oN x Silo Cyanarcus hamiformis Pascher, x 3000 Rhabdoderma irregulare (Naumann ) Geitler, x 750 Rhabdoderma lineare Schmidle & Lauterborn: 11, x 750; 12, x 1500 Merismopedia convoluta de Brébisson, x 600 Aphanothece stagnina (Spreng.) A. Braun: 14 and 16, habit, x 1; 15, x 750 [ 866 ] S Cs —— acta a Be (WS Wer FeUCOOUU UO i! OOCDDGOO © COG; Figo, Figs. 2, 3. Figs. 4, 5. Higs Ge Fig. 8. Figs. 9, 10. PLatTe 104 Aphanothece saxicola Naegeli, x 900 Aphanothece nidulans P. Richter: 2, x 750; 3 (drawn from a specimen in the Field Museum of Natural History ), x 1500 Pelogloea bacillifera Lauterborn, x 750 Aphanothece clathrata G. S. West: 6, x 900; 7, x 1500 Aphanothece gelatinosa (Henn. ) Lemmermann, x 750 Aphanothece microscopica Naegeli: 9, x 750; 10, cells in detail, x 1500 [ 868 | BIR aS rg bes EWBINA ree yp * oy. “A OBR RVG: Pao RO VOR ANS on P, ; Ne LOS SAGE ae OD 24 Bes ote ive eae MG, Q ie ne oe CANE NS KESAY Way. ae. Figs. 1, 2. Figs. 3, 4. Figs. 5, 6. Figs. 7-9. Figs. 10-12. Figs. 13-15. Fig. 16. Puate 105 Dactylococcopsis acicularis Lemmermann: 1, x 750; 2, S25 Dactylococcopsis Smithii Chodat & Chodat: 3, x 975; 4, x 490 Aphanothece Castagnei (de Bréb.) Rabenhorst: 5, x 1875; 6, x 1500 Aphanothece microspora (Menegh.) Rabenhorst: 7, habit of colony, x 1; 8 and 9, x 900 Dactylococcopsis fascicularis Lemmermann: 10, x 500; Vand 2 se7a0) Dactylococcopsis rhaphidioides Hansgirg: 13 and 14, Pleurocapsa, 590 ~ Pleurochloridaceae, 348 Pleurococcus. See Protococcus Pleurodiscus, 296 Pleurogaster, 353, also 349, 587 Junaris, 353; Pl. 95 oocystoides, 353; Pl. 95 Polyblepharidaceae, 68 Polycystis, 455, 592 Polyedriopsis, 271, also 235, 578 quadrispina 578 spinulosa, 272; Pl. 62 [974] Porphyridaceae, 563 Porphyridium, 563, also 586 cruentum, 564; Pl. 136 Potamogeton, 531, 560 Preservatives, 1x Production in lakes, 23, 34, 35, 37, 42 Protococcaceae, 126 Protococcus, 126, also 112, 575, 578, 580 viridis, 127; Pl. 10 Protoderma, 123, also 114, 583 viride, 123; Pls. 9, 14 Pseudotetraspora, 92 Pseudulvella, 123, 114, 583 americana, 124; Pl. 15 Pteromonas, 73, 572 angulosa, 73 Pyramimonas, 68, also 572 tetrarhyncus, 68; Pl. 1 Pyrrhophyta, 423, also 1, 2, 421 Quadrigula, 259, also 234, 282, 575 Chodatii, 260; Pl. 59 closterioides, 260; Pl. 58 lacustris, 260; Pl. 59 Raciborskia, 439, also 438, 589 bicornis, 440; Pl. 93 Radiofilum, 102, also 94, 582 apiculatus. See Radiofilum conjunctivum conjunctivum, 103, also 104; Pl. 7 flavescens, 103; Pl. 7 irregulare, 104, also 103; Pl. 7 Rhabdoderma, 462, also 445, 591 Gorskii, 463, also 462; Pl. 103 irregulare, 463, also 462; PI. 103 lineare, 463, also 462; Pl. 103 sigmoidea, 462 fa. minor, 463; Pl. 103 Rhizochloridales, 344, also 343 Rhizochrysidales, 380, also 369 Rhizochrysidaceae, 381 Rhizochrysis, 382, also 381, 589 limnetica, 382; Pl. 98 Rhizoclonium, 141, also 123, 135, 137, 138, 498, 500, 503, 540, 554, 581, 584 crassipelitum, 141; Pl. 23 var. robustum, 141 fontanum, 142, also 141; Pl. 23 hieroglyphicum, 142, also 141; Pl. 23 var. Hosfordii, 142 var. macromeres, 142 Hookeri, 143, also 141; Pl. 23 Rhizolekane, 344 Rhodophyceae, 562 Rhodophyta, 562, also 2 Ricciocarpus, 521, 525 Rivularia, 556, also 550, 557, 560, 593 haematites, 556; Pl. 131 minutula, 556; Pl. 136 Rivulariaceae, 550, also 478, 509 Sacconema, 560, also 550, 593 rupestre, 560; Pl. 136 Scenedesmaceae, 272, also 211 Scenedesmus, 273, also 212, 252, 272, 575, 578, 580 abundans, 274; Pl. 61 var. asymmetrica, 274; Pl. 61 var. brevicauda, 274; Pls. 61, 62 var. longicauda, 274; Pl. 62 var. spicatus, 274 acuminatus, 275, also 278; Pl. 62 var. minor, 275 var. tetradesmoides, 275 acutiformis, 275, also 273; Pl. 62 0 | arcuatus, 275, also 273; Pl. 62 var. capitatus, 275; Pl. 62 var. platydisca, 275; Pl. 62 armatus, 276, also 274; Pl. 62 var. Chodatii, 276 var. major, 276; Pls. 62, 63 var. subalternans, 276 | —_—s Bernardii, 276, also 272, 273; Pl. 63 var. undulatum, 228; Pl. 50 bijuga, 276, also 273; Pl. 63 spinulosum, 228; Pls. 50, 53 var. alternans, 277; Pl. 63 Spelaeopogon, 532 var. flexuosus, 277 Sphaerella (See Haematococcus ) var. irregularis, 277 lacustris, 80; Pls. 2, 3 brasiliensis, 277, also 274; Pl. 63 Sphaerellaceae, 80, also 68 denticulatus, 277, also 273; Pl. 63 Sphaerocystis, 83, also 82, 574 var. linearis, 277 Schroeteri, 83, also 88, 240; Pl. 3 dimorphus, 277, also 273; Pl. 63 Sphaeroplea, 111, also 110, 581 hystrix, 278, also 273;-Pl. 63 annulina, 111; Pl. 12 incrassatulus, 278, also 273; Pl. 63 Sphaeropleaceae, 111 var. mononae, 278; Pl. 63 Sphaeropleales, 110, also 66 longus, 278, also 274; Pls. 63, 64 Sphaerozosma, 359 var. brevispina, 278 Spirogyra, 307, also 6, 7, 295, 296, 581, 583 var. ellipticus, 278 aequinoctialis, 310, also 311; Pl. 72 var. minutus, 279 affinis, 311, also 310 var. Naegelii, 279; Pls. 63, 64 Borgeana, 311, also 310; Pl. 77 obliquus, 279, also 273; Pl. 63 borysthenica, 311, also 308 opoliensis, 279, also 274; Pl. 63 catenaeformis, 311, also 310 var. contacta, 279; Pl. 63 circumlineata, 312, also 309; PI. 74 perforatus, 279, also 274; Pl. 46 Collinsii, 312, also 309; Pl. 77 quadricauda, 280, also 274; Pl. 64 communis, 312, also 309 var. longispina, 280; Pl. 63 condensata, 312, also 309; Pl. 72 var. maximus, 280; Pl. 64 crassa, 312, also 28, 48, 310, 314; Pl. 72 var. parvus, 280; Pl. 64 daedalea, 321 var. quadrispina, 280; Pl. 63 daedaleoides, 313, also 309; Pl. 72 var. Westii, 281; Pl. 64 decimina, 313, also 28, 310 serratus, 281, also 273; Pl. 64 dubia, 313, also 310 Schizochlamys, 90, also 87, 574 ellipsospora, 313, also 310; Pl. 72 compacta, 90; Pl. 4 esthonica, 321 delicatula, 90 fallax, 314, also 308; Pl. 77 gelatinosa, 90; Pl. 4 Farlowii, 314, also 308 Schizogoniales, 67 flavescens, 314, also 309 Schizomeridaceae, 104 floridana, 319 Schizomeridineae, 104 fluviatilis, 314, also 310; Pl. 73 Schizomeris, 104, also 581 Fuellebornei, 315, also 310; Pl. 73 Leibleinii, 105; Pl. 7 gracilis, 315, also 309 Schizothrix, 506, also 479, 505, 593 gratiana, 315, also 308; Pl. 74 fasciculata, 507 Grevilleana, 315, also 308; Pl. 74 Friesii, 507, also 506; Pl. 114 illinoisensis, 319 fuscescens, 507, also 506; Pl. 114 inconstans, 315, also 308 lacustris, 507; Pl. 131 inflata, 316, also 308 lardacea, 508, also 506 Juergensii, 316, also 309; Pl. 73 Muelleri, 508, also 506; Pl. 114 jugalis, 316, also 310 rivularis, 508, also 506; Pl. 114 laxa, 316, also 308 tinctoria, 508, also 507; Pl. 131 longata, 316, also 309 vaginata, 509, also 507 majuscula, 317, also 310; Pl. 74 Schroederia, 255, also 234, 578 maxima, 317, also 310, 314 Judayi, 256, also 255; Pl. 57 micropunctata, 317, also 309; Pl. 73 setigera, 256, also 255; Pl. 57 mirabilis, 317, also 309; Pl. 77 Scirpus, 548 nitida, 318, also 310; Pl. 73 Scytonema, 533, also 595 novae-angliae, 318, also 310; Pl. 75 alatum, 534; Pl. 123 orientalis, 318, also 310 Archangelii, 534; Pl. 123 porangabae, 318, also 309; Pl. 77 cincinnatum. See Scytonema crispum porticalis, 318, also 309; Pl. 75 coactile, 534; Pl. 124 pratensis, 319, also 309; Pl. 75 crispum, 535, also 534; Pl. 124 protecta, 319, also 308 figuratum. See Scytonema mirabile pseudofloridana, 319, also 310; Pl. {fe mirabile, 535, also 533, 534; Pl. 124 reflexa, 319, also 309 var. tolypothricoides. See Scytonema rhizobrachialis, 320, also 310; Pl. 76 tolypothricoides rivularis, 320, also 310 myochrous, 535, also 534; Pls. 124, 125 scrobiculata, 320, also 309; Pl. 76 ocellatum, 25 singularis, 320, also 309 tolypothrichoides, 536, also 534; Pl. 123 Spreeiana, 321, also 308; Pl. 77 Scytonemataceae, 532, also 478, 543 stictica, 321, also 310; Pl. 76 Seepage lakes. See Lakes subsalsa, 321, also 309; Pl. 73 Selenastrum, 256, also 235, 575 suecica, 321, also 309 Bibraianum, 256; Pl. 57 sulcata, 321, also 309 gracile, 257, also 256; Pl. 57 tenuissima, 322, also 308 minutum, 257, also 256; Pl. 46 Teodoresci, 322, also 310 Westii, 257, also 256; Pl. 57 triplicata, 322, also 310 Silicon, 342, 370, 375, 385 varians, 322, also 310; Pl. 76 Siphonales, 266, also 67 Weberi, 322, also 308; Pl. 76 Sirogonium, 296 Spirulina, 479, also 478, 481, 591, 592 Snapping turtle, 47, 143 laxa, 479; Pl. 108 Sodium arsenite, 45 laxissima, 480, also 479; Pl. 107 Soft water lakes. See Lakes major, 480, also 479; Pl. 108 Soils, 5, 8, 11 Nordstedtii, 480, also 479; Pl. 108 Sorastrum, 227, also 219, 577 princeps, 480, also 479; Pl. 108 americanum, 228; Pl. 50 subsalsa, 480, also 479; Pl. 108 [975] Spondylomoraceae, 79, also 68 Spondylomorum, 79. also 572 quaternarium, 80; Pl. 3 Spongilla, 235 Staurastrum, 18, 938, Pl. 3 (Appendix) Staurogenia multiseta var. punctata, 285 Stentor, 235 Stephanodiscus, 409, 943, Pl. 5 (Appendix) niagarae, 11 Stephanosphaera, 81, also 80, 572 pluvialis, 81; Pl. 46 Stichococcus, 98, also 95, 582 bacillaris, 99; Pl. 6 fa. confervoidea, 99 scopulinus, 99; Pl. 6 subtilis, 99; Pl. 6 Stigeoclonium, 114, also 98, 113, 583, 584 attenuatum, 115, also 114; Pl. 13 flagelliferum, 115; Pl. 11 lubricum, 115, also 116; Pl. 10 nanum, 116, also 114; Pl. 9 pachydermum, 116, also 114; Pl. 12 polymorphum, 116, also 114; Pl. 9 stagnatile, 117, also 114; Pl. 11 subsecundum, 117, also 114; Pl. 10 tenue, 117, also 115 Stigonema, 546, also 548, 549, 594 mamillosum, 547; Pl. 130 mesentericum, 548, also 547; Pl. 130 ocellatum, 548, also 547, 594; Pl. 130 tomentosum. See Stigonema ocellatum turfaceum, 548, also 547; Pl. 129 Stigonemataceae, 543, also 478 Stipitococcaceae, 344 Stipitococcus, 344, also 588 apiculatus, 345, also 344; Pl. 93 capense, 345; Pl. 93 crassistipatus, 345; Pl. 93 urceolatus, 346, also 344; Pl. 93 vasiformis, 346, also 345; Pl. 95 Stylosphaeridium, 91, also 579 stipitatum, 92; Pl. 4 Symploca, 504, also 479, 593 muscorum, 504; Pl. 113 Syncrypta volvox, 374 Syncryptaceae, 374 Synechococcus, 460, also 445, 591 aeruginosus, 461; Pl. 102 Synura, 375, also 19, 590 Adamsii, 375; Pl. 92 uvella, 376, also 374, 375; Pl. 92 var. longipes, 376 Synuraceae, 374 Temnogametum, 296 Temperature, 43 Tetradesmus, 282, also 272, 577 Smithii, 282; Pl. 64 wisconsinense, 283, also 282; Pl. 64 Tetradinium, 440, also 438, 589 javanicum, 440; Pl. 93 simplex, 440; Pl. 107 Tetraédron, 260, also 233, 235, 242, 271, 578, 580 armatum, 262; Pl. 59 arthrodesmiforme, 262, also 261; Pl. 59 var. contorta, 263; Pl. 59 asymmetricum, 263, also 262; Pl. 59 bifurcatum, 263, also 261; Pl. 59 var. minor, 263; Pl. 59 caudatum, 263, also 261; Pl. 59 var. incisum, 263 var. longispinum, 264; Pl. 59 constrictum, 264, also 262; Pl. 59 cruciatum, 264, also 262 var. reductum, 264; Pl. 59 duospinum, 264; Pl. 46 enorme, 265, also 262; Pls. 52, 59 var, pentaedricum, 265; Pl. 59 gigas, 265, also 261 var. granulatum, 265 gracile, 265, also 262; Pl. 60 hastatum, 265, also 262; Pl. 59 var. palatinum, 266; Pl. 59 irregulare, 263 limneticum, 266, also 262; Pl. 60 var. gracile, 266; Pl. 60 lobulatum, 266, also 262; Pl. 60 var. crassum, 266; Pl. 60 var. polyfurcatum, 267; Pl. 60 lunula, 267, also 261; Pl. 60 minimum, 267, also 261; Pl. 60 var. scrobiculatum, 267 muticum, 267, also 261; Pl. 60 fa. punctulatum, 268; Pl. 60 obesum, 268, also 261; Pl. 60 pentaedricum, 268, also 261; Pl. 60 planctonicum, 268, also 262; Pl. 60 pusillum, 268, also 262; Pl. 60 quadratum, 268, also 261; Pl. 46 regulare, 269, also 261; Pl. 60 var. bifurcatum, 269; Pl. 61 var. granulata, 269; Pl. 61 var. incus, 269; Pl. 61 fa. major, 269; Pl. 61 var. torsum, 269; Pl. 61 staurastroides, 271 trigonum, 270, also 261; Pl. 61 var. gracile, 270; Pl. 61 var. papilliferum, 270 var. setigerum. See Treubaria setigerum tumidulum, 270, also 261; Pl. 61 verrucosum, 270, also 261; Pl. 61 Victoriae, 270, also 261 var. major, 270; Pl. 61 Tetragoniella, 354, also 349, 588 gigas, 354; Pl. 95 Tetrallantos, 287, also 272, 575, 577 Lagerheimii, 287; Pl. 66 Tetraspora, 87, also 89, 126, 236, 573, 574 cylindrica, 88, also 87; Pl. 5 gelatinosa, 88, also 87; Pl. 5 lacustris, 88; Pl. 5 lamellosa, 88, also 87; PI. 5 lubrica, 89, also 88; Pl. 5 Tetrasporaceae, 87, also 82, 475 Tetrasporales, 81, also 66 Tetrastrum, 286, also 272, 576 punctatum, 286 staurogeniaeforme, 286; Pl. 66 Thorea ramosissima, 564 Thoreaceae, 564 Tolypella, 333, also 331, 585 intricata, 334; Pl. 78 Tolypothrix, 536, also 509, 533, 535, 540, 595 conglutinata, 537, also 536; Pl. 125 distorta, 537, also 536; Pl. 125 lanata, 537, also 536; Pl. 125 limbata, 538, also 536; Pl. 126 tenuis, 538, also 536, 537 var. Wartmanniana, 538 Trachelomonas, 407, also 19, 388, 389, 408, 571, 585 abrupta, 410; Pl. 83 acanthostoma, 410, also 408; Pls. 83, 85 aculeata, 408 fa. brevispinosa, 410; Pl. 85 armata, 410, also 409; Pl. 83 fa. inevoluta, 411; Pl. 83 var. longispina, 411; Pl. 83 var. Steinii, 411; Pl. 83 bulla, 411, also 408; Pl. 84 charkowiensis, 411, also 408; Pl. 85 crebea, 411, also 408 var. brevicollaris, 412; Pl. 84. cylindrica, 412, also 410; Pl. 83 var. punctata. See Trachelomonas lacustris [976] dubia, 412, also 409; Pl. 85 Dybowskii, 412, also 410; Pls. 83, 84 erecta, 412, also 410; Pl. 85 euchlora, 413, also 409; Pl. 89 Girardiana, 413, also 408; Pl. 84 granulosa, 413, also 409; Pl. 89 hexangulata, 413, also 409; Pl. 85 var. repanda, 413; Pl. 84 hispida, 414, also 409; Pl. 83 var. coronata, 414; Pl. 83 var. crenulatocollis fa. recta, 414; Pl. 88 var. papillata, 414; Pl. 84 var. punctata, 414; Pl. 84 horrida, 415, also 408, 409; Pl. 84 intermedia, 415, also 410; Pl. 83 Kelloggii, 415, also 409; Pl. 83 lacustris, 415, also 410; Pls. 83, 85 mammillosa, 415, also 410; Pl. 85 peridiniformis, 415 Playfairii, 416, also 409; Pl. 85 pulchella, 416, also 409; Pl. 83 pulcherrima, 416, also 410; Pl. 83 var. minor, 416; Pl. 83 robusta, 416, also 409; Pl. 83 rotunda, 416, also 409; Pl. 83 scabra var. longicollis, 417, also 408; Pl. 85 similis, 417, also 408; Pls. 84, 85 speciosa, 417, also 408; Pl. 84 spectabilis, 417, also 409; Pl. 85 superba, 417, also 409; Pl. 84 var. duplex, 417; Pl. 84 var. spinosa, 418; Pl. 84 var. Swirenkiana, 418; Pls. 83, 84 sydneyensis, 418, also 409; Pl. 84 triangularis, 418, also 409; Pl. 83 varians, 418, also 409; Pl. 83 volvocina, 419, also 409, 414; Pl. 83 var. compressa, 419; Pl. 83 var. punctata, 419; Pl. 83 Trachychloron, 354, also 349, 588 biconicum, 354; Pl. 95 depauperatum, 355, also 354; Pl. 95 Trentepohlia, 133, also 132, 571, 582, 584 aurea, 133; Pl. 67 var. polycarpa, 134 Tolithus, 134, also 133; Pl. 19 Trentepohliaceae, 132 Treubaria, 241, also 233, 578 setigerum, 242; Pl. 51 Tribonema, 366, also 19, 105, 218, 365, 883, 582, 587 aequale, 368 affine, 367; Pl. 96 bombycinum, 367; Pl. 96 var. tenue, 367; Pl. 96 minus, 368, also 367; Pl. 96 utriculosum, 368, also 367; Pl. 96 viride, 367 Tribonemataceae, 366 Tribonematales, 365 Trichodesmium, 479, 593 lacustre. See Oscillatoria lacustris Trochiscia, 238, also 234, 579 aspera, 239, also 238; Pl. 53 granulata, 239, also 238; Pl. 53 obtusa, 239, also 238; Pl. 52 reticularis, 239, also 238; Pl. 53 sporoides, 239 Zachariasii, 239, also 238; Pl. 53 Tuomeya, 569, also 586 fluviatilis, 570; Pl. 132 Turtles, 47, 134, 143 Tychoplankton, 3. See also Plankton Ulothrix, 95, also 94, 98, 582 aequalis, 96, also 95; Pl. 6 cylindricum, 96, also 95; Pl. 6 moniliformis, 102 subconstricta, 96, also 95; Pl. 6 [977] subtilissima, 96, also 95; Pl. 6 tenerrima, 96, also 95; Pl. 6 tenuissima, 97, also 95; Pl. 67 variabilis, 97, also 95; Pl. 6 zonata, 97, also 95; Pl. 6 Ulotrichaceae, 94 Ulotrichales, 93, also 66 Ulotrichineae, 94 Ulvales, 67 Ulvella, 583 Urococcus, 82 Uroglenopsis, 380, also 376, 590 americana, 380; Pl. 99 Uronema, 98, also 94, 582 elongatum, 98; Pl. 5 Utricularia, 502, 542, 548 Vacuolaria virescens, 421 Vaucheria, 290, also 289, 585 aversa, 291; Pl. 66 geminata, 292, also 291; Pl. 68 var. depressa, 292 hamata, 292, also 291 longipes, 292, also 291; Pl. 67 Nicholsii, 293, also 291; Pl. 67 ornithocephala, 291 orthocarpa, 293, also 291; Pl. 67 pachyderma, 293, also 291; Pl. 67 polysperma, 293, also 291; Pl. 67 sessilis, 294, also 291; Pl. 68 fa. clavata, 294; Pl. 67 terrestris, 294, also 291; Pl. 68 Vaucheriaceae, 289, also 288 Volvocaceae, 73, also 68 Volvocales, 67, also 1, 66 Volvox, 77, also 15, 73, 74, 572 aureus, 78; Pl. 2 globator, 78; Pl. 2 mononae. See Volvox tertius tertius, 79, also 78; Pl. 3 Water blooms, 7, 17, 44, 376 Westella, 237, also 234, 577 botryoides, 237; Pl. 53 var. major, 237 linearis, 237; Pl. 53 Wollea, 526, also 510, 594 saccata, 526; Pl. 122 Xanthophyceae, 2, 342 Xanthophyll, 421 Zoochlorella, 235, also 233, 236, 579 conductrix, 235; Pl. 53 parasitica, 235; Pl. 53 Zooplankton, 24 Zygnema, 323, also 23, 296, 327, 329, 581 carinatum, 324; Pl. 78 chalybeospermum, 324, also 323; Pl. 74 conspicuum, 324 cyanosporum, 325, also 324 decussatum, 325, also 324 insigne, 325, also 324 leiospermum, 325, also 324; Pl. 78 micropunctatum, 325, also 324; Pl. 78 pectinatum, 325, also 324; Pl. 69 stellinum, 326, also 324 sterile, 326, also 323 synadelphum, 326, also 323; Pl. 74 Zygnemataceae, 295 Zygnematales, 294, also 66 Zygnemopsis, 326, also 296, 581 americana, 327 decussata, 327; Pl. 74 desmidioides, 328, also 327; Pl. 69 minuta, 328, also 327 spiralis, 328, also 327; Pl. 69 Tiffaniana, 328, also 327; Pl. 74 Zygogonium, 329, also 581 ericetorum, 329; Pl. 78 re VY j a3 i jee) a rl ees vie Uf i} wif, ap) if fa 4 54 SSS oe S oe- Ono @- 0 ba me tee rer sey> yararare tase be 53525? wits gave ReBpSED tek Heesains op esa reece Sipe steng2s8 tabapea gsi ipepay eee pdfedc gees. 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