; H=? ! CD tr m o m o TUFTS COLLEGE STUDIES (SCIENTIFIC SERIES) VOLUME II PUBLISHED BY THE CHARLES HYDE OLMSTEAD FUND TUFTS COLLEGE, MASS. 1905-1909 23 CONTENTS. NUMBER I. DECEMBER, 1905. I. G. E. MARION: Mandibular and pharyngeal muscles of Acanthias and Ruia. (American Naturalist, 39, pp. 891-920, 1905.) 15 text figures i NUMBER II. MAY, 1906. II. F. W. THYNG : The squamosal bone in tetrapodous Vertebrata. (Proceedings of the Boston Society of Natural History, 32, pp. 387-425.) 3 plates, one table, and 20 text figures . 35 NUMBER (^11. JULY, 1909. III. F. S. COLLINS : The Green Algae of North America. 1 8 plates ......... 79 THE GREEN ALGAE OF NORTH AMERICA THE TU1-TS COLLEGE PRKSS TUFTS COLLEGE STUDIES, Vol. II, No. 3. THE GREEN ALGAE OF NORTH AMERICA.* BY FRANK S. COLLINS. TABLE OF CONTENTS. PAGE INTRODUCTION . . 80 CLASS HETEROKONTAE. 92 Order I. Confervales 92 Family i. Confervaceae 92 2. Botrydiaceae • •' 97 3. Chlorotheciaceae 99 CLASS CHLOROPHYCEAE. 100 Order I. Conjugates 101 Family i. Desmidiaceae (omitted) 101 2. Zygnemaceae . 102 3. Mesocarpaceae 121 Order II. Volvocales 127 Family i. Chlamydomouadaceae 128 2. Volvocaceae 131 3. Tetrasporaceae 136 Order III. Protococcales 142 Family i. Protococcaceae 142 2. Protosiphonaceae 153 3. Halosphaeraceae 154 4. Scenedestnaceae 155 5. Hydrodictyaceae 175 Order IV. Ulotrichales ^ 180 Family i. Ulotrichaceae ..." 180 2. Ulvaceae 195 3. Prasiolaceae 217 4. Cylindrocapsaceae 222 5. Oedogoniaceae 222 6. Chaetophoraceae 275 "Contributions from the Harpswell Laboratory of Tufts College, No. 32 TUFTS COLLEGE STUDIES, VOL. II, No. 3 PAGE Family 7. Herposteiraceae -510 8. Coleochaetaceae .... -512 9. Trentepohliaceae 315 Order V. Siphonocladiales 321 Family i. Cladophoraceae 321 2. Gomontiaceae 370 3. Valoniaceae - 371 4. Dasycladaceae 377 5. Sphaeropleaceae 384 Order VI. Siphonales 385 Family i. Codiaceae 386 2. Bryopsidaceae 402 3. Derbesiaceae 406 4. Phyllosiphonaceae . . 407 5. Caulerpaceae 408 6. Vaucheriaceae • 421 List of works to which reference is made ........ 433 Description of plates . 456 Index . , 463 INTRODUCTION. In the following pages it is intended to give an account of the green algae of North America, with as much detail as will en- able the student to recognize the species, and have some idea of their development and affinities. North America in this sense includes everything from the Arctic Ocean to the Isthmus of Panama, including the West India Islands. In the green algae are included not only the Chlorophyceae, in the narrower sense, but also the small class of the Heterokontae. On the other hand two families are omitted, the Desmidiaceae and the Char- aceae ; the former, though closel}^ related to the other Conju- gales, has generally been taken as a separate study, for special students ; to include it with as much detail as the other algae would practically double the size of this work ; moreover the American desmids are not well enough known at present. The Characeae, on the other hand, are widely separated from all other algae, representing the last term in a long line of develop- ment, diverging from the main line at some remote time, so remote that it is hard to guess at what point it started. THE GREEN ALGAE OF NORTH AMERICA Si Under each species will be found a concise description, with a record of the localities in which it has been found ; if in the United States, the State is given, but seldom any more exact location. Reference is given to the original publication of the binomial, also to some good plate or figure ; where there has been distributed in some set of exsiccatae a specimen that can be identified with the species in question, reference is made to this ; by preference use is made of the Phycotheca Boreali- Americana of Collins, Holden & Setchell, as being at once the fullest for American algae, and the most accessible for Ameri- can students. References are also given to three standard works : - - Harvey, 1852, Farlow, 1881, and Wolle, 1887. Where the basis of treatment of any family or genus has been the monograph of any author, reference is made to such monograph under each species. In special cases other references have , seemed desirable, and have been made. In the plates there will be found at least one figure for each genus ; in most cases these are taken from standard works, often from the original description of the species represented. Where a choice had to be made of the species to be represented, in some cases a type was selected other than the one most famil- iar to American students in the usual text books. It has not seemed necessary to furnish any glossary of botani- cal terms used, but such terms as are special to the forms here described, and which would not be found in ordinary botanical works, have been included in the index, with a reference to the page in which they are used and explained. In the present imperfect state of our knowledge of the green algae, it would be unsafe to make deductions as to distribution from the records of localities here given, that is, as to their ab- •sence from regions not noted. In fresh water algae especially the greater part of our territory is "terra incognita." Begin- ning at the north, we have Greenland, with a limited flora of fresh water algae, but probably as completely known, thanks to the Danish botanists, as that of any other region of the same size within our scope. New York and New Kngland have been considerably explored, and there are some few records from West. India Islands. The fresh water algae of California ; nd 82 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Oregon, near the coast, have been collected to a considerable extent within the past few years ; but for the rest of the United States there is only the record of a few species, here and there, at isolated stations. Lists have indeed been published, at various times, of local floras, but when the attempt has been made to see the material on which these lists were based, it has usually been found impossible ; in the few cases where the material was accessible, so many determinations were found to require correction as to make it out of the question to accept the determinations of lists whose material could not now be exam- ined. For such great regions as Canada and Mexico practically no records exist. As regards marine algae the case is not quite so bad. They follow the seashore, and it is easier to become familiar with the narrow strip that represents their distribution, than with the great enclosed area through wrhich the fresh water species are to be found. The stretches of shore of which we are still ignorant are not disgracefully long. But while in fresh water collections the green algae constitute the greater part, and include the most conspicuous forms, the collector at the shore, if not a specialist, is likely to bring away the showy brown and red algae, to the neglect of the less notable green plants. The marine flora of Greenland is as well known as that of any region of the size ; that of the New England coast has been studied for many years, but from New Jersey to Florida, published records are quite insignificant. Some recent observations at Beaufort, North Carolina, at the lab- orator}- of the U. S. Bureau of Fisheries, which the authori- ties have kindl}- allowed to be here used, to some extent supply this deficiency ; the flora of Key West is probably as well known as any tropical or subtropical flora ; lists of con- siderable completeness have been published for_ a number of the West India Islands. But beginning with the west coast of Florida, all the way round the Gulf of Mexico to the isthmus, we have practically no records ; the same is the case on the Pacific coast from the isthmus to California ; from the Mexico- California boundary north to the Arctic Ocean observations have pretty well covered the coast line, and it is not likely that any special flora has escaped our notice. This does not mean THE GREEN ALGAE OF NORTH AMERICA 83 that we are fully acquainted with any region ; even on the New England coast, which has been studied so long, species new to the region are continually turning up. Not only in comparing different regions, but in comparing different families and genera, the treatment must be unequal. For the family of the Oedogoniaceae, for instance, we have Hirn's admirable monograph, based on an ample supply of material, American as well as foreign; from this a very satis- factory account of this family can here be given, but with the proviso that species described by Him from extra-American localities will probably some time be found here. Of the genus Chlamydomonas Wille has published a thorough re- vision, but with no reference to American material or locali- ties ; little attention has been given to the genus here ; only fresh material can be used for study, so that practically the genus will remain unrepresented. A case different from both these is presented by the genus Cladophora ; probably more species have been described in this genus than in any other genus of algae, except possibly some of the minute diatoms and desmids. Cladophoras abound everywhere, in fresh and salt water ; herbarium specimens are practically as good for pur- poses of determination as the living plants ; and yet this genus presents more difficulties than any other treated in this work. Species have been described recklessly, from imperfect material, often with little or no consideration of what had before been de- scribed ; the plants vary much in response to environment, and the individual plant may vary much at different stages of growth, but except in a very few instances we have no investi- gations to show just what forms belong in the same life cycle. These three instances show the inequality that exists, and must long exist, in our knowledge of the different types about to be considered. Under each genus will be found a key, for convenience in identifying plants under consideration. These keys are based as far as possible on the more obvious characters, which are not necessarily the more important systematically, but the sys- tematic characters will be found in the appropriate place under each species. The characters used will apply only to the 84 TUFTS COLLEGE STUDIES, VOL. II, No. 3 species here given, and would mislead if used for species of other regions. Each distinction in the key being founded on a single character, it may sometimes happen that one will be led in this way to a specific description differing in other characters from the plant in hand ; in such case it may be that it is a species new to this region, and reference should be had to more general works. At the end of the descriptive part of the work will be found a list of the works referred to, arranged alphabetically by authors, the date being given after the author's name : in the text the reference will be by name and date only, full particulars of title, etc., being given in the list. This does not attempt to be a full catalogue of works on American algae ; for an account of these, published previously to 1889, see De Toui, 1889 ; for works with special reference to American algae, see Tilden, 1895 ; later than these dates the bibliographical notes in Just's Botanischer Jahresbericht, Nuova Notarisia, Botanische Cen- tralblatt and Hedwigia will be useful, as also the Index to American Botanical Literature in the Bulletin of the Torrey Botanical Club. The labels of the several numbers in the Phy- cotheca Boreali- Americana often have a prett)7 full bibliography of the species. In nomenclature, the rules of the Vienna Congress have been used as a basis ; but as these rules were adopted completely only as to the higher plants, the question of a starting point for the nomenclature of algae being referred to a future congress, it has seemed unwise at present unnecessarily to disturb well established names. As regards classification, the general ar- rangement is that of Oltmanns, 1904, but with some variations in detail. Anything of the character of the present work, whatever name appears as that of its author, represents, if it is of any value, the work of many individuals. Limitations of space pre- vent giving exact localities and collectors' names under the several species, and so man}7 have aided the \vriter by con- tributions of material from localities that he could not himself visit, that a general acknowledgement of their assistance must suffice. But a few names must be mentioned. To Prof. W. G. THE GREEN ALGAE OF NORTH AMERICA 85 Farlow of Harvard University the writer owes his first encour- agement in the stud}- of -algae; for this, for assistance and advice through many years, and for the opportunity to consult his unrivalled library and collections, the most hearty acknowl- edgement is offered. With Prof. W. A. Setchell of the Uni- versity of California the writer has been associated for many years in collecting and studying, and much of value in the present work is due to his contributions and suggestions. That so good a representation can be given of the green algae, marine and fresh water, of the Pacific coast States, is chiefly due to Dr. N. L. Gardner of Los Angeles, California, an acute observer and indefatigable collector. To many European botanists thanks are due for information as to types and for materials for comparison ; most of all to Dr. Edouard Bornet of Paris, the value of whose advice and assistance is equalled only by the unfailing promptness and courtesy with which they were given. To Prof. J. vS. Kingsley and Prof. F. D. Lambert of Tufts College, the writer is indebted for opportunities for collecting and stud}' during the seasons he has been at the Laboratory at Harpswell, Maine, and for many facilities given and kindnesses shown ; the plates which it is hoped will add materially to the value of the paper are also their work. No one can know as well as the writer how incomplete the work is, and how likely it is that errors will be detected ; but no pains have been spared to make it as complete and accurate as possible. There can be no question that a work on the sub- ject has been needed ; if this will stimulate study and increase knowledge, so that a better work can soon take its place, it will have justified its existence. Before algae are studied they must be collected, and a few hints in this regard may be of use. Only the green algae will be taken into account in this respect, but as the different types of green algae require different treatment, practically every contingency as to other types of algae will be provided for. In temperate regions the marine green algae are largely littoral plants, that is, inhabiting the zone between high and low water marks ; in quiet bays and pools they ma}7 form dense floating 86 TUFTS COLLEGE STUDIES, VOL. II, No. 3 masses, but very few have to be sought below low water mark. In the extreme north the temperature and the shore ice permit practically nothing to exist uncovered by water, and all algae must be obtained by dredging. The same result is reached, in part, in the subtropical waters of the West India region, but by different causes ; tides are slight and irregular, and exposure for any length of time to the intense sunshine would be fatal to delicate forms ; here also one must look below the surface. In many genera of marine Chlorophyceae the individual plants are large enough to be easily seen (Ulva, Cladophora, Udotea, etc.) but for the greater part only the mass, not the individual, can be distinguished (Rhizoclonium , Codiolum, etc.) while others appear as a thin film on wood or stone (Pseudendo- clonium, Pilinia, etc.) or as a coloration of the shell in which they are imbedded (Gomontia). Then there are endophytic forms (Bolbocolcon, Chlorochytrium) not at all manifest, and only to be found by dissection of the host plant. These conditions being so varied, the only safe course for a student is to collect every- thing of a green color that he does not recognize. Few of the marine green algae are specially sensitive ; in most cases they can be kept a reasonable time immersed in salt water, or packed in cloths moistened with salt water, if not subjected to higher temperature than that of the water in which they grew ; but if plants or portions of plants to be studied must be kept for sev- eral days, it is better to keep them in salt water to which enough ordinary formalin (formaldehyde) has been added to make a three per cent, solution. Of course no action of the living plant can then be observed, but the structure is main- tained practically intact for months, as far as would be needed for anything described in this work. For permanent preserva- tion of these algae, nothing is better than the herbarium form. In many genera whatever characters are needed for systematic purposes can be obtained from herbarium specimens, and in those cases where characters cannot be made out as satisfac- torily in the dried specimens as in fluid preparations, at any rate whatever is available continues so for an indefinite time, while it is only too common to find a fluid preparation worthless. As regards microscopic slides, they can be prepared so as to show THE GREEN ALGAE OF NORTH AMERICA 87 beautifully some particular structure, but here too, permanence is far from assured. Moreover the slide shows just the one thing in the one position ; there is no changing or moving it. There are some genera of tropical algae that can be prepared for the herbarium practically the same as flowering plants (cal- careous algae like Halimcda, and coarse non-calcareous forms like Avrain-cillca) by pressing between driers and then strapping or gluing to herbarium sheets. Of green algae of temperate regions Ulva and some species of Cladophora and Chactomorpha are all that can be treated in this way ; most species that are of sufficient size for the individual fronds to be shown (Bryopsis, most Cladophoras) should be mounted on paper, and the paper attached to the herbarium sheet ; the plant should be allowed to spread out in natural form in a shallow dish or pan of salt water, the paper placed under it and carefully raised, until it, with the undisturbed specimen, is lifted out. The papers are then placed on driers, specimens up, a piece of cotton cloth the size of a drier laid over all ; then another drier, specimens, cloth, etc. After this the process is much as for flowering plants ; greater or less pressure according to the char- acter of the specimens ; changes of driers as fast as they become moist, but no change of cloths ; these not to be removed until specimens are thoroughly dry and ready for the herbarium. The heaviest driers should be used, as the amount of moisture to be taken up is so much more than in land plants. Frequent change of driers, and having them thoroughly dr}^ when used, will add much to the value of the specimens. Nearly all algae prepared in this \vay will adhere to the paper. Those forms in which the individual plants are minute (Codiolum, Prasinodadus) of course cannot be treated in this way ; a small portion of the thin pasty mass can be spread with a knife on a piece of paper, and then dried without cover or pressure. It is sometimes better to use mica instead of paper for very minute forms; they are then ready, when moistened, for microscopic examination, without removing from paper to slide. Where mica is used and a large number of specimens are to be prepared, it is often convenient to add more water and drop from a pipette on the mica. 88 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The three methods just given practically ausvver all require- ments for marine algae. There are no fresh water algae that will require the first method ; a few (Cladopkora, Oedogonium) are best treated by the second, but the greater part require the third. In collecting fresh water algae it will be found to be the rare exception that a species can be recognized in the field ; one must sample everywhere ; at first the abundance of new forms will be so great that a few such samplings will give materials for hours of study ; later, as one is more familiar with the flora of a region, the proportion of novelties becomes smaller, and after a while one is satisfied if only nine out of ten collectings are thrown away after a hasty examination. On the other hand, one will often find in a small bottle of material enough forms for days of study. In such families as the Zygnemaceae and Oedogoniaceae only fruiting specimens are accurately determinable ; in all but a few of the larger forms the micro- scope is needed to decide as to the presence or absence of fruit. One must continue to collect, though the proportion of prizes will grow steadily less. As a partial recompense, one often finds minute epiphytic algae attached to the larger sterile plants and minute plankton forms lying loose among them. These minute unattached forms are very interesting, and have been studied but little in this country. Wonderful collections can sometimes be made by drawing a fine net through the water, but a surprising variety can also be found entangled among Utricularia and other water plants, or adhering to the gelatinous coating on stems and leaves of Pontcdcria, Brascnia, etc. In the latter case the material can be scraped off; in the former it is better to squeeze the plants thoroughly, remoisten and again squeeze ; this can be repeated many times before the supply of algae fails. If the liquid stands in a jar or bottle, in a ' few hours the algae will settle to the bottom ; the liquid can be drawn or carefully poured off. If then formalin be added, enough to make the liquid a three per cent, solution, the ma- terial can be studied at leisure. The effect of formalin is not permanent, and where perma- nence is needed, other preparation must be used. The technic THE GREEN ALGAE OF NORTH AMERICA 89 for microscopic, histological and cytological work is now so elaborate and varied that no attempt can be made here to give any details. Perhaps the best reference for it is Chamberlain's Methods in Plant Histology. One process specially useful in studying herbarium specimens of green algae appears not to be generally known or generally mentioned in the technical works, and it may be well to note it here. When a herbarium specimen of a green alga is mois- tened and submitted to microscopic examination, it is often found that the shape of the cell as well as of the chromatophore has been lost in the shrinking in drying, and not recovered by moistening. If then the bit of moistened alga is laid on the slide, in a drop or two of concentrated lactic acid, then warmed until bubbles appear in the fluid, it will often be found on put- ting on the cover glass and examining the specimen, that the structure of the original has been much restored. The instructions just given for collecting and preparing algae are more in the way of hints and suggestions than of full direc- tions. One learns by practice, and not much any other way ; the "knack," the little contrivances, will soon be acquired. Those who prefer fuller directions will find them in Harvey, 1852, Farlow, 1881, Setchell, 1899, Collins, 1899, West, 1904. Many kinds of algae can be kept alive for a long time, with proper care as to fresh water, light etc.; development can be studied, and often new and unexpected forms may appear; by adding certain substances to the water, reproductive organs of different kinds can often be developed ; but this, as well as the matter of pure cultures, opens up too large a field for the present work. As regards classification, a brief notice should be given. Any statement, even approximately full, of the supposed phylogeny and relations of the green algae would require more space than can be given in a work of this character. The most plausible theory now is that the green algae are descended from the Flagellates, a class of organisms that has been claimed (and de- clined) both by botanists and zoologists. The Flagellates are actively moving unicellular organisms, and in nearly all the green algae this ancestral form reappears as the zoospore, the 90 TUFTS COLLEGE STUDIES, VOL. II, No. 3 permanent condition in the ancestor being only the transient condition in the descendant. Two distinct lines seem to be traceable, from two types of Flagellates ; one producing the small class of Heterokontae, the other the remaining green algae. Some authors have further divided the latter, and as the Heterokontae derive their name from the unequal cilia of the motile stage, the name Isokontae has been proposed for algae whose motile spores have two equal cilia ; the Akontae for those with no motile ciliate stage, and the Stephanokontae for those with many cilia arranged in a circle. But -this desire for symmetry seems to come under the head of " trop de zele " ; there is fully as much reason to suppose that the Conjugales (Akontae) have lost the motile stage possessed by their ances- tors, and that some at least of the multiciliate organisms are modifications of the biciliate type. See Davis, 1908. From the nature of the case, all the forms here to be described must be arranged in a linear series, but it is to be hoped that no one will suppose that their relative rank can be determined by their position in the series. The general arrangement is from the more simple to the more complex ; Order A, the simpler, being followed by Order B, the more complex ; and in each order family a, the simpler, is followed by family b, the more complex ; but it is almost always the case that family z, the most complex of Order A, is considerably in advance of family a in Order B. A glance at one of the diagrams that have been made to show the probable filiation of the different types will give an idea of the complexity of the matter. Change is not necessariby progress ; retrogression is often evident. The preservation of the individual or of the type may be secured by very many appliances or adaptations, thus forming diverging lines of development, some reaching a point where further progress in that line is impossible, others continuing, perhaps giving off lateral lines here and there. All schemes of showing these tendencies and results assume the former existence of in- termediate forms, now extinct; and so imperfect is our knowl- knowledge of what remains, that it is evident that man}- schemes may yet be proposed before we have one satisfying all the requirements. No attempt will here be made to give any such THE GREEN ALGAE OF NORTH AMERICA 91 schemes; those interested will find them in Bohlin, 1901 a; Blackman and Tansley, 1902; West, 1904; Oltmanns, 1905. The general statement of the classification used here is this : - One small class, the Heterokontae, including algae whose motile cells have cilia of unequal length ; whose vegetative cells con- tain chromatophores colored yellowish with xanthophyll, with- out pyrenoid, and whose reserve materials are in the form of oil rather than starch. The other class, the Chlorophyceae, in- cludes all algae with true chlorophyll-green chromatophores, starch reserves, pyrenoids usually present, and whose motile cells have cilia of equal length. The Heterokontae contain but one order, Confervales ; the Chlorophyceae six ; Volvocales with the motile stage more prominent than the non-motile ; Conjugates, with no motile stage ; and four others with repro- duction by various sexual or non-sexual motile spores or by aplanospores, evidently a modification of the zoospores ; in these orders there is so much variety in this respect, other char- acters often remaining unchanged, that a classification based on the reproductive bodies would seem highly artificial, a distinc- tion based on other characters more natural. So we have the uninucleate Protococcales, the cells solitary or in loose colonies ; the membranaceous or filamentous Ulotrichales, also with uni- nucleate cells ; Siphonocladiales with multinucleate cells ; and Siphonales with no distinction of cells, the many nuclei distrib- uted all through the interior of the plant. In each of these orders there is great diversity of characters, both as to com- plexity of structure and as to reproductive characters ; ex- tremely simple vegetative growth being accompanied with very elaborate reproductive mechanism in Oedogonium and Vaitcheria, for instance ; remarkable variety of external form in the various species of Caitlerpa, with no reproductive process whatever known. In many genera, even of conspicuous plants, we still have to write " reproduction not well known " or even " repro- duction unknown." The division of the orders into families will appear as the}' are reached in the following pages, and requires no comment here. 92 TUFTS COLLEGE STUDIES, VOL. II, No. Class I. HETEROKONTAE. Motile cells with two cilia of unequal length ; chromatophore more or less distinctly yellow green ; reserve material oil, not starch ; no pyrenoids. Under this name are included by Oltmanns and others, the family Chloromonadaceae of the Flagellates, with genera of algae supposed to be derived from it ; in distinction from the great body of green algae, whose descent is from other forms of Flagellates ; the name is based on the unequal length of the two cilia, one of the two being sometimes quite imperceptible ; though the distinction may appear somewhat artificial, it seems to cover a distinct line of descent and development. Only one order of algae. Order CONFERVALES. KEY TO THE FAMILIES OF CONFERVALES. i. Terrestrial; cell vesicular, with branching underground prolonga- tions. 2. BOTRYDIACEAE. i. Chiefly aquatic ; filamentous or unicellular, without branching pro- longations. 2. 2. Unicellular; cells free or connected by gelatinous strands ; sexual reproduction by gametes. 3. CHLOROTHECIACEAE. 2. Unicellular or filamentous ; cell wall with little cellulose ; sexual reproduction unknown. i. CONFERVACEAE. Family I. CONFERVACEAE. Cells free or united in attached or free monosiphonous fila- ments ; cell wall with little cellulose, mostly pectin ; chromato- phores usually many, disk-shaped, always without pyrenoid, cells containing more or less oily matter but no starch, one or more nuclei ; asexual reproduction by zoospores with two cilia of unequal length, or by aplanospores which often seem to take the place of zoospores under certain conditions of environment ; all plants of fresh water. The Confervaceae, as here limited, include genera that have been placed at widely different points in the series of green algae, and their association here is by no means free from ques- tions ; some of them have been reported as having two cilia of equal length, some as having only one ; but these reports may be due to imperfect observations. In most of the genera there is a peculiar stratified arrangement of the cell wall, by which the THE GREEN ALGAE OF NORTH AMERICA 93 upper part fits over the lower, like the cover on a pill box ; in Conferva this results, when the cell breaks open, in the forma- tion of the so-called H sections, formed of the upper half of one cell and the lower half of the cell above it. KEY TO THE GENERA OF CONFERVACEAE. i. Cells elongate. 2. i. Cells globose or subglobose. 3. 2. Cells uuited into filaments. 4. CONFERVA. 2. Cells solitary or attached by their slender bases. 2. OPHIOCYTIUM. 3. Cells united into gelatinous filaments. 3. CHLOROBOTRYS. 3. Cells solitary, free. i. BOTRYDIOPSIS. i. BOTRYDIOPSIS Borzi, 1894, p. 199. Frond unicellular, globose or subglobose, uninucleate, free ; containing more or less numerous small chromatophores without pyrenoid. Asexual reproduction by numerous zoospores, show- ing amoeboid changes of form and having two unequal cilia. The type species, B. arhiza Borzi, has not been found in this country, but two new species have been described, as below. Nothing is known of them other than the descriptions of Miss Snow, and their distinctness from the European species may be questioned. B. ERIENSIS Snow, 1903, p. 384, PI. Ill, fig. XIII, 1-7. Cells 1 8-2 1 /j. diam.; chromatophores hexagonal when young, elon- gate when older: zoospores usually 16 or 32 in a cell, escaping through an opening in the cell wall, about 5X3 p, with red stigma, and only one cilium showing distinctly. Fig. i. N. Y. B. OLEACEA Snow, 1903, p. 385, PI. Ill, fig. XII, i-io. Similar to B . ericnsis, but less regularly globose, not over 13 //. cliam., chromatophores densely packed, a red globule near the center of the cell; zoospores 5-8X3-5 /*• N. Y. 2. OPHIOCYTIUM Nageli, 1849, p. 87. Cells free or attached to water plants, multinucleate, cylindri- cal or claviform, one end frequently capitately swollen ; straight, arched, curved in S-form or spirally ; solitary or in umbellate or corymbose families ; at each end rounded, truncate, or mucron- ate, or rounded at one end and with a stipe or spine at the other; chromatophores many, parietal, without pyrenoid; cells sometimes containing yellowish oil globules ; asexual reproduc- tion by aplanospores, or by biciliate, ovoid-oblong zoospores, formed few to many in a cell, escaping by the breaking off of 94 TUFTS COLLEGE STUDIES, VOL. II, No. 3 the cap-like end of the cell ; in some species germinating di- rectly at the summit of the mother cell, in others entirely inde- pendently. Not uncommon among other algae, especially the unattached forms ; but seldom found in large quantity. The present treat- ment of this genus follows Lemmerman, 1899, including Scia- dium, generally kept distinct on account of the new generation developing at the summit of the older cell ; but as this same development is found in varieties of some species of Ophiocvtium, in the older sense, the distinction cannot be kept up. KEY TO THE SPECIES OF OPHIOCYTIUM. i. Attached. 2. i. Free. 3. 2. Cells 5-7 ^ diain., stipe 10-14 /x long. 6. O. gracilipes. 2. Cells 3-5 M diain., stipe 2-3.5 M long. 5. O. arbuscula. 3. Bearing a stipe or spine. 4. 3. Both ends rounded or truncate. 4. O. parrulum. 4. Stipe with capitate end. i. O.majus. 4. Stipe or spine acute. 5. 5. Spine at one end. 2. O. cochleare. 5. Spines at both ends. 3. O. capitatum. 1. O. MAJUS Nageli, 1848, p. 89, PI. IV. A, fig. 2; ^em- merman, 1899, p. 29; Phyk. Univ., No. 19, b. Cells solitary, 8-17 fj- diarn., spiral or curved in S-form ; at one end with a straight or curved stipe with capitate end ; cells often with hya- line or yellowish oil globules. Fig. 2. Mass. Europe. 2. O. COCHLEARE (Eichwald) A. Braun, 1855, p. 54 ; Wolle, 1887, p. 175, PL CLVIII, figs. 8-14; Lemmerman, 1899, p. 30, PL III, figs. 10-12; P. B.-A., No. 1424. Cells solitary, 5-8 /x diam., arched or spirally twisted, bearing at one end an acute spine i- 1 2 p long. Me., Mass. Europe. 3. O. CAPITATUM Wolle, 1887, p. 176, PI. CLVIII, figs. 3«-7 ; Lemnierman, 1899, p. 31, PI. IV, figs. 16-18. Cells soli- tary, 5-10 /Jt- diam., arched, S-curved or spiral, with an acute spine 5-7 M long at each usually swollen end. Mass., N. Y. 4. O. PARVULUM (Perty) A. Braun, 1855, p. 55 ; Wolle, 1877, p. 176; Lemmerman, 1899, p. 33, PI. IV, figs. 31-33; Rabenhorst, Algen, Nos. 516, 1546. Cells solitary, 3-9 /u, diam., straight, arched or spiral, rounded at each end. Greenland, Me., Mass., N. Y. Europe. Yar. CIRCINATUM (Wolle) Lemmermau, 1899, p. 34, figs. 15-18; O. circinatnm Wolle, 1887, p. 176, PI. CLVIII, figs. THE GREEN ALGAE OF NORTH AMERICA 95 15-18. Cells solitary, 10-13 M diam., in a spiral of two to many turns, both ends rounded. Minn. Europe. Larger than the type, and always in a spiral, usually of many turns. 5. O. ARBUSCULA (A. Br.) Rabenhorst, 1868, p. 68; Lem- merman, 1899, p. 28 ; Sciadium arbuscitla A. Braun, 1855, p. 49 PI. IV; Wolle, 1877, p. 174, PI. CLVII, figs. 1-6 ; Wittr. and Nordst., Alg. Exsicc., Nos. 401, 1360. Cells always united in families, umbellate or corymbose, straight, 3-5 p. diam. ; stipe slender, 2-3.5 /* long- connecting the lower end with the basal disk. Mass. "Specimens from three or four states." Wolle. Europe. 6. O. GRACILIPES (A. Br. ) Rabenhorst, 1868, p. 68 ; Lem- merman, 1899, p. 28; Sciadium gracilipes Wolle, 1887, p. 175, PI. CLYII, figs. 7 and 8; Bohlin, 18973, PL I, figs. 27-32, 35, 39, 40; PI. II, figs. 59 and 60. Cells in a simple umbel, 5-7^ diam., stipe 10-14 M !ong, to the disk-like base. Minn. Europe* 3. CHLOROBOTRYS Bohlin, 1901, p. 34. Cells globose, with several disk-shaped chrornatophores with- out pyrenoid, with more or less oil ; cells 2-16 united by a hya- line tegument ; asexual reproduction by short cylindrical akinetes, with thickened membrane, formed from vegetative cells ; also by cell division. Only one species. C. REGULARIS (West) Bohlin, 1901, p. 34, fig. 9; West, !9Q4, p. 254, fig. 119. Cells globose, 10-27 /j. diam., united by a gelatinous coating into families up to 90 fj. diam. including the coating, cells sometimes in contact ; chrornatophores 6-30 in a cell ; asexual reproduction by division of a cell into 2-4 daughter cells, also by akinetes. Fig. 3. Common in various parts of Europe, and reported by West from the United States. 4. CONFERVA Linnaeus, 1737, p. 326. Filaments at first attached by a special basal cell, later free ; cells uniuucleate, rarely with two nuclei ; chromatophores disk- shaped, two to many in a cell, without pyrenoid, producing oil but not starch ; cell wall thin, breaking up into H sections. *O. CUSPIDATUM (Bailey) Rabeuhorst, 1868, p. 68; Wolle, 1887, p. 176, PI. CL/VIII, figs. 1-2; Closterinni cnsf>idatnw Bailey, in Ralfs, 1848, p. 219, PI. XXXV, fig. n ; Xei-HSf/iic/la .' cus^idata De Toni, 1889, p. 614. A problematical plant ; it is doubtful if it belongs to any one of the gen- era in which it has been placed, and it certainly deserves investigation. The cells are crescent-shaped with rounded ends, like a broad Clos- terimn, each end terminated by a stout spine. The cells measure 150X165 n, the spines are 15 M long. 96 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Asexual reproduction by 2-ciliate zoospores without red stigma produced 1-4 in a cell ; also by aplanospores. Under the name Conferva, dating back to the time of Pliny, Linnaeus included the greater part of the filamentous algae ; by the steady segregation of a century and a half, it has been re- duced to a small group of fresh water algae, and is here taken in the extension given it by Lagerheim, 1889, p. 194. On account of the impossibility of determining what plant was the 'type,' in the taxonomical sense, of L/innaeus, Hazen proposes to drop the name Conferva entirely, substituting the Tribonema of Derbes and Solier, of 1856. This seems rather too heroic treatment, as all the plants included in Lagerheim's Conferva have long borne that name, would certainly have been included by Linnaeus under it, and cannot be placed in any other accepted genus. , KEY TO TDE SPECIES OF CONFERVA. i. Chroruatophores 2-4, symmetrically disposed. 2. C. minor. i. Chroniatophores numerous. 2. 2. Filaments 3-6 M diam. i. C. bombycina forma tennis. 2. Filaments 6-n M diam. i. C. bombycina. 2. Filaments 11-16 M diam. 3. C. utricnlosa. i. C. BOMBYCINA Agardh, 1817, p. 78; Wolle, 1887, p. 142, PI. CXXI, figs. 8 and 9; P. B.-A., Nos. 620, 1278; Tribonema bombydnutn Hazen, 1902, p. 184, PI. XXV, figs. 1-3. Forming a yellowish or whitish floccose mass ; filaments 6-n p. diam., cells cylindrical or somewhat inflated, 2-4 diam. long ; cell wall thin ; chromatophores small or of moderate size, several in a cell. Fig. 4. Maine to No. Carolina ; Alaska to Vancouver Island ; probably everywhere. Europe. A very common spring plant in roadside pools and brooks ; the disk-shaped chromatophores distinguish it from Aftcrospora and other filamentous algae of the same size, and the dimensions separate it fairly well from other species of Conferva. Forma tenuis (Hazen) nov. comb.; Tribonema bombycinum forma tcnue Hazen, 1902, p. 185, PI. XXV, figs. 4-6; Con- ferva bombycina forma minor Wille, P. B.-A., No. 621. Cells 3-6 fji diam., 2-12 diam. long, little if any inflated; chromato- phores several, small. Greenland, Maine to N. J. Europe. A small, delicate, long-celled form, often found with the type ; it is probably only a condition, but has quite a different appear- ance. THE GREEN ALGAE OF NORTH AMERICA 97 2. C. MINOR Klebs, 1896, p. 347, PI. II, figs. i-S ; P. B.-A., No. 1327 ; Tribonema minus Hazen, 1902, p. 185, PI. XXV, figs. 7 and 8. Cells cylindrical or very slightly inflated, 5-6 p diam., 2-4 or even 6 diam. long ; chromatophores 2 or 4 in a cell, arranged in pairs. Mass, to N. J. Europe. In habit similar to C. bombycina, and in dimensions not unlike forms of that species, but quite distinct in the symmetrical arrangement of the 2 or 4 chromatophores. 3. C. UTRICULOSA Kiitzing, Decades, No. 114; Wolle, 1887, p. 140, PI. CXX, figs. 14-16; P. B.-A., Nos. 1071 and 1223; Tribonema utriculosum Hazen, 1902, p. 186, PI. XXV, figs. 9-11. Filaments 11-16 /* diam.; cells usually inflated, but somewhat irregularly, occasionally cylindrical, 1^2-6 diam. long, rarely more ; chromatophores large and often crowded ; cell wall rela- tively thick. Mass, to N. J.; Jamaica. Europe. Our largest species, having thicker cell walls and larger chromatophores than the others ; the cells less uniform in size and shape ; the Jamaica plant has cells up to 12 diam. long ; like the other species chiefly a spring plant. Many species originally included in Conferva will now be found under other genera ; in some cases, however, the descrip- tions are not sufficiently full to determine the genus. Among the latter are C. sesquipedale Montague, 1859, p. 173, from Louisiana; C. antillarum Kiitzing, 1853, p. 15, PI. XLV, fig. 2, from Trinidad; C. serpens Kiitzing, 1849, p. 372; 1853, p. 15, PI. XlyVI, fig. 2, from Texas ; C. centrifuga Agardh, 1854, p. 109, from Nicaragua. Family 2. BOTRYDIACEAE. Unicellular, multinucleate, with numerous lens- or spindle- shaped chromatophores ; with vesicular part above ground, rhizoidal part below ; asexual reproduction by uniciliate zo- ospores, and by aplanospores. Only one genus. BOTRYDIUM Wallroth, 1815, p. 153. Frond stoutly clavate or globose, with branched lower portion containing protoplasm ; asexual reproduction by uniciliate zo- ospores, formed in large numbers by simultaneous division of the cell contents, escaping by an opening at the summit ; either de- veloping into vegetative plants, or passing into resting spores with thick membrane, which later may develop vegetative plants. 98 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Under special conditions round or ovoid aplanospores may be formed in large numbers in the root portions ; these aplanospores may either produce zoospores, or grow directly into new plants. After much confusion in regard to this genus, the studies of Rostafinski and Woronin, 1877, appeared to settle the matter, and since that time the genus has been considered as consisting only of a single species, exceedingly polymorphous in its adapta- tions to varying conditions. But the more recent investigations of Klebs, 1896, and Iwanoff, 1898, show that apparently at least three species must be distinguished, and one of these constitutes a new genus, Protosiphon. The other two species continue in Botrydium. There is no way of determining to which of these three species any record of Botrydium granulatum may refer ; but fortunately all three species are included in the material distributed under that name in published American exsiccatae, and can be described here ; few other localities than those of the exsiccatae can be given, KEY TO THE SPECIES OF BOTRYDIUM. i. Portion of cell above ground clavate with thin wall. i. B. granulatum. I. Portion of cell above ground spherical with thick, stratified wall. 2. B. Wallrothii. 1. B. GRANULATUM (L,.) Greville, 1830, p. 196, PI. XIX; Rostafinski and Woronin, 1877, p. 16, in part, PL I.; Wolle, 1887, p. 155, in part, PI. CXXXI, figs. 1-9 ; P. B.-A.,No. 226. Exposed portion 1-2 mm. diain., broadly clavate or obovoid, with bright green contents and thin wall, tapering below to the much branched subterranean portion ; zoospores formed in the upper part, 10-20X5-8 /J. ; aplanospores formed in the lower por- tion, globose or oblong, up to 50 ^ diam. On moist ground, especially clay ; probably generally distributed. Fig. 5. Mass., N. Y., Cal. Europe, So. America, New Zealand. 2. B. WALLROTHII Kiitzing, 1839, p. 387; B. granulatum Rostafinski and Woronin, 1877, p. 16, in part, PI. Ill, figs. 25- 28 ; Tilden, American Algae, No. 45, in part. Exposed portion globose, rarely equalling i mm. diam., with dense, dark olive green contents and thick, much stratified membrane, passing without transition into the narrow, cylindri- cal underground portion, which for some distance is simple, then branching relatively slightly ; the wall in the upper part of this portion is so thick as almost to close the opening. On moist ground. Minn. Europe. THE GREEN ALGAE OF NORTH AMERICA 99 The specimens distributed by Miss Tilden consist of this species in company with Protosiphon botryoides (Kiitz.) Klebs. Family 3. CHLOROTHECIACEAE- Unicellular, attached ; asexual reproduction by (uniciliate ?) zoospores formed one or more in a cell ; sexual reproduction by (uniciliate ?) gametes formed one or more in the vegetative cell, or from cells developed in greater or less number within the vegetative cell ; by union of these is formed a normal plant, either directly or by means of another generation of zoospores. In one genus there is a vegetative ^ division of the cells, the daughter cells attached by gelatinous stalks in a tree-like colony. Fresh water plants. Only one genus represented here. CHARACIOPSIS Borzi, 1894, p. 151. Cells pyriform or ovoid, with several chromatophores, at- tached ; erect or oblique, with longer or shorter stipe ; asexual reproduction by uniciliate zoospores (possibly biciliate with one cilium much reduced) formed many in a cell, developing directly into a plant like the parent ; sexual reproduction by the forma- tion of numerous cells, with membrane, each producing 2-4 zoogametes, by whose conjugation is formed a resting zygote, ultimately developing into a plant like the parent. In habit the species of this genus closely resemble species of Characium, but possess a sexual reproduction, and have zo- ospores with only one cilium or with merely the rudiment of a second cilium. In Characium there is only one chromatophore ; in Gharaciopsis several chromatophores in a cell. KEY TO THE SPECIES OF CHARACIOPSIS. i. Without basal disk. 2. i. With basal disk. 3. 2. Cell ellipsoid with rounded summit. 3. C. cllipsoidea. 2. Cell lanceolate with acute or apiculate summit. 2. C. iniiiitta. 3. Stipitate, outline broadly lanceolate or ovate. i. C. acuta. 3. Sessile, outline narrowly lanceolate, acuminate, more or less oblique. 4. C. subidata. 1. C. ACUTA (A. Br.) Borzi, 1894, P- X53 > Characium acittum A. Braun, 1855, p. 41, PI. V. C.; Wolle, 1887, p. 177, PI. CLJX, fig. 2. Cell 15-20X6-10 /A, erect, straight, broadly lanceolate or ovate in outline, equall)^ attenuate each way, sub- acute, opening at the top ; stipe slender, 5-10 //, long, expanded below into a brownish disk. Pa. Europe. 2. C- MIXUTA (A. Br.) Bor/i, 1894, p. 152 ; Characium minutum A. Braun in Kiitzing, 1849, p. 892 ; 1855, p. 46, PI. ioo TUFTS COLLEGE STUDIES, VOL. II, No. 3 V. F.; P. B.-A., No. 1221. Cell 17-25X5 /j., lanceolate in outline, more or less oblique, subacute or apiculate, apiculum straight or curved ; stipe short, base not expanded. Fig. 6. Mass., Cal. Europe. 3. C. ELLIPSOIDEA G. S.West, 1905, p. 288, PL CCCCLXIV, fig. 8. Cells 15-22X8-10 /j., ellipsoid, apex obtusely rounded, stipe stout, very short, without basal disk ; chrornatophores 4. Barbados. The stipe is so short that the cell might be considered practi- cally sessile. 4. C. SUBULATA (A. Br.) Borzi, 1894, p. 152 ; P. B.-A., No. 1370 ; Characiuin subulatuin A. Braun, 1855, p. 47, PI. V. G. Cell 12-20X4-5 /x- obliquely lanceolate, sessile, with no distinct stipe, but with sharply contracted base and basal disk ; apex acuminate, more or less oblique ; cells often gregarious, with confluent basal disks. Cal. Europe. Class II. CHLOROPHYCEAE. Algae of true green color, usually producing starch, almost always with pyrenoid ; reproduction in most cases by pyriform zoospores, with cilia of equal length, attached to the smaller end ; mostly two, sometimes four, in a few genera many cilia ; zoogametes of similar form, with two or four cilia. Motionless spores of various kinds, and sexual reproduction by oogonia and antheridia, are found in many genera. KEY TO THE ORDERS OF CHLOROPHYCEAE. i. Frond of oue or more cells. 2. i. Frond usually of relatively large size, multinucleate, without dis- tinction of cells. 6. SIPHONALES. 2. Vegetative cells ciliate and motile, always or except during resting periods, or easily passing into a motile condition. 2. VOLYOCALES. 2. Vegetative cells motionless ; reproductive cells motile or not. 3. 3. Reproduction by zygospores formed by the union of two non-motile cells. i. CONJUGATES. 3. Reproduction by zoospores, zoogametes or aplanospores, not by zygospores as above. 4. 4. Cells solitary or in spherical or net-like combinations. 3. PROTOCOCCALES. 4. Cells forming simple or branched filaments or membranes, rarely proliferously branching and vesicular cells. 5. 5. Cells uuinucleate, chromatophore usually single, disk-, net-, or star-shaped. 4. ULOTRICHALES. THE GRE*EN ALGAE OP NORTH AMERICA 101 5. Cells uiulti nucleate, chromatophore net-shaped, or of numerous small disks in a cell. 5. SIPHOXOCI.ADIALES. Order I. CONJVGAI.KS. Grass-green algae, starch forming, with cell wall of cellulose, whose cells divide only in one direction, and are either isolated or in filaments ; not incrusted with lime. Zygospores formed by the union of the protoplasm of two similar or only slightly different cells ' ' aplanogametes ' ' ; after a longer or shorter resting period the outer membrane of the spore breaks, and a new vege- tative development sets in. Thick-walled resting cells "akin- etes " and asexual spores " aplaiiospores " sometimes formed; no motile spores. The Conjugales are distributed all over the world, and seem more independent of geographic limitations than other algae. Of the 47 species of Z3'gnemaceaehere described, all but three occur in Europe. While there is no such knowlege of these plants in Asia and Africa as there is in Europe and America, what species have been observed are very largely the familiar forms of the better explored regions. In view of this cosmopolitanism, any localities given must be considered as indicating where specimens have been found, not as limiting the range of distrib- ution. All are plants of fresh water, only rarely extending into brackish water. KEY TO THE FAMILIES OF CONJUGATES. i. Cells usually divided by a constriction into symmetrical halves; solitary or in filaments ; the cell arising from the germinating zygospore either taking the normal form or producing 2-8 such forms. (DESMIDIACEAE.) i. Cells cylindrical, without constrictions, always united in filaments; the new filament always formed directly from the zygospore. 2. 2. The entire protoplasmic contents of the conjugating cells uniting to form the spore. i. XYGXEMACEAE. 2. Only a part of the contents of the conjugating cells used for the spore. 2. MESOCARPACEAE. The family Desmidiaceae is not included in this work. Rich in genera and species, it constitutes a special field apart from other algae, and for its proper presentation a special treatment would be needed. The two other families are closely related and distinctly marked off from all other green algae by the character of the fructification. 102 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Family i. ZYGNEMACEAE. Filaments sometimes attached, more generally free, all cells except the original basal cell equally capable of division ; fila- ments simple or rarely with short rhizoidal branches ; chromat- ophores of different shapes in the different genera ; zygospores formed by the union of the contents of two cells, either of the same filament (lateral conjugation), or of distinct filaments (sca- lariform conjugation) ; formed either in one of the two cells, or in the passage between them. Spore with membrane of three layers, of which the middle layer, mesospore, is the thickest and usually colored brown or yellow in the ripe spore, and often with pits or other markings. In germination the two outer layers are broken, the inner forming the membrane of the new plant, which at once divides into an indivisible basal cell, and a continuously divisible filament cell. KEY TO THE GENERA OF ZYGNEMACEAE. i. Two cells uniting to form one, before the formation of the spore. 2. i. Each cell dividing; spore then formed by the union of the two sec- ondary cells. 4. ZYGOGONIUM. 2. Chrouiatophores two, star-shaped. i. ZVGNEMA. 2. Chromatophores one or more, parietal, more or less spiral. 2. SPIROGYRA. 2. Chromatophore an axial plate. 3. DEBARYA. i. ZYGNEMA Agardh, 1814, p. 33. Cells cylindrical, about as long as broad or somewhat longer ; dissepiments smooth and even ; two axillary stellate chromato- phores in each cell, each with a pyrenoid, the nucleus between the two. Conjugation lateral or scalariform ; zygospore formed either in the connecting tube or in one of the cells ; spore with median membrane colored, either smooth or pitted ; outer mem- brane colorless, smooth or with prominences. Aplanospores formed in unchanged vegetative cells and similar in appearance to zygospores. Akinetes formed from single cells taking on a thicker membrane and richer contents ; both aplanospores and akinetes exceptional. KEY TO THE SPECIES OF ZYGNEMA. i. Spore formed in the tube. Sect. PECTINATA. 2. i. Spore formed in one of the cells. 4. 2. Spore with thick, lamellate membrane. „ 2. Z. pachydermuDi. 2. Spore without thick lamellate membrane. 3. 3. Spore bluish. 3. Z. cyanospermum. 3. Spore brownish. i. Z. pectinatmn. 4. Spore with smooth median membrane. Sect. LEIOSPERMA. 5. THE GREEN ALGAE OF NORTH AMERICA 103 4. Spore with pitted median membrane. Sect. SCROBICULATA. 7. 5. Spore bluish. 4. Z. chalybeospennum. 5. Spore brownish. 6. 6. Vegetative filaments 20-22 /j. diam. 5. ' Z. leiospermum. 6. Vegetative filaments 26-30 fj. diarn. 6. Z. insigne. 7. vSpores uniformly globose. 7. Z. cruciatuin. 7. Spores usually oblong. 8. Z. stellinum. 1. Z. PECTINATUM (Vauch.) Agardh, 1817, p. 102; De Bary, 1858, p. 77, PI. I, figs. 15-19; PI. VIII, Fig. 13; Zygo- gonium pedinatum Wolle, 1887, p. 225, PI. CXLV, figs, i and 2 ; P. B.-A., No. 1216. Vegetative cells 30-37 /x diam., 1-3 diam. long ; membrane at first thin, later with a thick, gelati- nous sheath ; conjugation scalariform ; spores globose or broadly ellipsoid, about 50 /u, diam.; membrane brown, distinctly pitted. Mass., N. J. Europe, So. America. Var. ANOMALUM (Ralfs) Kirchner, 1878, p. 126; Z. anoma- luni var. crassnin Wolle, 1887, p. 224, PI. CXLJV, figs. 9-13. Cells 40-50 n diam.; membrane very thick. Vermont, Mass., Conn. Europe. Var. DECUSSATUM (Vauch.) Kirchner, 1878, p. 127; P. B.-A., 1415. Zygogoninm decussatum Wolle, 1887, p. 226, PI. CXIyV, figs. 4 and 5. Cells 18-20 ^ diam., membrane not con- spicuously gelatinous. Mass.; "Ponds, stagnant and sluggish water." Wolle. Europe. Forma TERRESTRE (Rab.) Kirchner, 1878, p. 127; P. B.-A., No. 1365. Membrane thick, dark-colored, cell shorter than in the type ; on ground along the edges of ponds. Mass. Europe. 2. Z. PACHYDERMUM W. and G. S. West, 1895, p. 266, PI. XII, figs. 1-16. Filaments flexuous, somewhat geniculate ; vegetative cells 16-23 M, usually 20 /j. diam., 2-3 diam. long; membrane up to 5 /u- thick ; short, irregular, rhizoidal branches of 2-6 cells frequent ; conjugation scalariform ; spores globose, subglobose, ellipsoid or of irregular shape, 25-35X19-26 //.; membrane up to 6 ^ thick, lamellate ; aplanospores similar but somewhat smaller and with thinner membrane. In warm muddy water. Dominica. Var. CONFERVOIDES W. and G. S. West, 1895, p. 266, PI. XIV, figs. 1-6. Cells 10-13 /a diam., I~2 diam. long; reproduc- tion unknown. With the type. The irregularly formed spores with thick, lamellate walls may be a result of the peculiar thermal conditions under which this species occurs ; but it can hardly be considered as a form of any other of our species. 104 TUFTS COLLEGE STUDIES, VOL. II, No. 3 3. Z. CYANOSPERMUM Cleve, 1868, p. 28, PL VIII, figs. 6-8. Vegetative cells about 20 ^ diam., 2-9 diam. long ; conju- gation scalariform ; spores globose, 34-40 /x diam., in the short tube; membrane bluish, smooth. Greenland. Northern Europe. 4. Z. CHALYBEOSPERMUM Hausgirg, iSSSa, p. 257 ; P. B.-A., No. 808. Vegetative cells 24-27 /u. diam., 1-3 diam. long, fertile cells shorter ; membrane delicate ; conjugation scalariform ; spores globose or subglobose, about 35 ^ diam. ; median mem- brane bluish, smooth ; cells containing spore somewhat inflated. Cal. Europe. 5' Z. LEIOSPERMUM De Bary, 1858, p. 77, PL I, figs. 7-14; Wolle, 1887, p. 222, PL CXLJII, figs. 1-3; Rabenhorst, Algen, No. 638. Vegetative cells 20-22 // diam., as long or slightly more ; conjugation scalariform or lateral ; fertile cells somewhat swollen and shortened ; spores smooth, globose or broadly ovoid, brownish, 23-30 p. diam., escaping from the cell before fully ripe. Greenland, Mass. Europe. 6. Z. INSIGNE (Hass.) Kiitzing, 1849, p. 444; 18553, p. 5, PL XVII, fig. i ; De Bary, 1858, p. 78, PL VIII, figs. 14-16: Wolle, 1887, p. 223, PL CXLJII, figs. 4-6; P. B.-A., No. 457. Vegetative cells 26-30 /x diam., length equal to diam. or up to 2 diam. ; cylindrical or swollen on one side ; conjugation scalari- form or lateral; spores 30-32 /j. diam., brownish, remaining en- closed after maturity by the persistent cell wall. Mass., N. J., Cal. Europe. Differs from the preceding species chiefly in dimensions, but also by the different behavior of the ripe spore. 7. Z. CRUCIATUM (Vauch.) Agardh, 1817, p. 102 ; Kiitzing, i855a, p. 5, PL XVII, fig. 4; Wolle, 1887, p. 224, PL CXLIV, figs, i and 2; P. B.-A., No. 758. Vegetative cells 35-54 ^ diam., as long or somewhat longer; conjugation scalariform; spores globose, brown, about 40 /* cliam., median membrane finely punctate ; fertile cells not swollen. Mass., N. J. Europe, So. America . 8. Z. STELLINUM (Miiller) Agarclh, 1824, p. 77 ; Wolle, 1887, p. 223, PL CXLIII, figs. 7-17; P.B.A., No. 1172. Vegetative cells 25-36 p diam., 1-3 diam. long; conjugation scalariform or lateral; spores ovoid or oblong, 35-48X30-35)11, brown, median membrane with rounded pits ; fertile cells hardly swollen. Fig. 7. Greenland, Mass., Conn., N. J. Europe. The dimensions are for the type ; a number of forms have been described, in some of which the cell diameter does not THE GREEN ALGAE OF NORTH AMERICA 105 exceed 10 /*. The larger forms are distinguished from Z. cruci- atum chiefly by the form of the spores, ovoid rather than glo- bose ; also by the somewhat coarser marking of the membrane. 2. SPIROGYRA L,ink, 1820, p. 5. Cells cylindrical, once to many times as long as broad ; dis- sepiments either smooth and even or with ring-like projections ; chromatophores one or more in a cell, in the form of parietal, more or less spirally bent, broad or narrow bands, each contain- ing several pyrenoids ; nucleus in the middle of the cell. Con- jugation lateral or scalariform ; spore formed in one of the two conjugating cells; median membrane colored, smooth or pitted ; germinating spore producing a more or less clavate filament. A genus of many species, of world-wide distribution ; the specific distinctions not always clear, based on the character of the dissepiments, the number and breadth of the chromato- phores, the size and form of the spore, the character of its median membrane, the inflation of the fertile cell, and, too often, the dimensions of the filaments ; this last character being too un- certain to have much weight, except when associated uniformly with other characters. The size and shape of the spore is of more importance, but it must be kept in mind that a change of position in the cell may give a totally different aspect to the spore when seen under the microscope. An ovoid spore appears circular when its axis is in the line of vision ; and a lenticular spore varies from circular to a quite narrow oval, according to the angle at which it is seen. Good plates are of the utmost use in determining species of Spirogyra ; the best work available is Petit, 1880. Of the 37 species there figured, 32 are given in the following pages, and there is no reason why the remaining five should not be expected in America. In ad- dition to the zygospores, parthenospores are sometimes formed, the usual process not extending to the union of the tubes from the two cells ; spores formed in one or both of the filament cells. Aplanospores occasionally formed, as in Zygnema. The following key may be of assistance in determining species, but in a rather general way. KEY TO THE SPECIES OF SPIROGYRA. i. Cell conjugating directly, not by a tube. 38. 5". stidica. i. Cell emitting a tube. 2. 106 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. Dissepiments plane. 3. 2. Dissepiments replicate. 27. 3. Chromatophore single. 4. 3. Chroniatophores two or more. 16. 4. Spore membrane punctate. 27. S. punctata. 4. Spore membrane smooth. 5. 5. Fertile cells not distinctly swollen. 6. 5. Fertile cells distinctly swollen. 10. 6. Cells less than 30 M diam. 7. 6. Cells 30 M diam. or more. 9. 7. Spore ovoid, slightly longer than the diam. ; cells 22-25 M diam. 9. 5. snbsalsa. 7. Spore ellipsoid, 2-3 times as long as the diam. 8. 8. Chromatophore slender, with inconspicuous pyrenoids. 7. 5. communis. 8. Chromatophore slender, with many large, distinct pyrenoids. 3. 5". Jnergensii. 8. Chromatophore broad. \. S. longata. 9. Cells 30-48 //, diam. 2. 5. porticalis. 9. Cells 48-70 fj. diam. 8» 6". condensata. 10. Fertile cells swollen on one side only. n. 10. Fertile cells swollen on both sides. 12. n. Cells 18-22 /j. diam. 21. 5. gracilis. ii. Cells 33-40 M diam. 5. 5. varians. 12. Chromatophore slender. 13. 12. Chromatophore broad. 14. 13. Cells 27-30 /A diam. ; spore 30-33x33-45 M- 18. 5. affinis. 13. Cells 40-45 M diam. ; spore about 47 M diam., of varying shape. 6. 5. fusco-atra. 14. Cells 11-13 M diam. ; spore about 20X30 /a. 20. S. flavesccns. 14. Cells 24-27 M diam. 15. 14. Cells 30-43 ft. diam. ; spore 30-42X70-120 /j.. 22. S. lutctiana. 15. Spore 30X60-75 fj.. 4. S. catenaeformis. 15. Spore 24-26X38-50 M, formed without conjugation. 19. S. mirabilis. 16. Chroniatophores two, rarely three. 17. 16. Chromatophores regularly three or more. 18. 17. Cells 27-40 /u. diam. . 10. S. decimina. 17. Cells 43-50 M diam. 26. S. dubia. 18. Spore lenticular. 19. 18. Spore ovoid, ellipsoid or subglobose. 21. 19. Cells 100 /j. diam. or more. 16. .9. maxima. 19. Cells less than 100 /u diam. 20. 20. Fertile cells little or not swollen. 15. S. orthospira. 20. Fertile cells distinctly swollen. 25. 5. bellis. 21. Cells 90-160 M diam. 22. THE GREEN ALGAE OF NORTH AMERICA 107 21. 22. 22. 22. 23- 23- 24. 24. Cells 80 fj. diam. or less. Cells 150-160 M diatn. ; chromatophores many. 17 Cells loo-no fj. diam. ; chromatophores 4-8. 13. 6 Cells 90-100 n diam. ; chromatophores 3-4. 12. Cells less than 40 /j. diam. Cells 50-80 fa diam. Chromatophores 4. 24. 23- S. crassa. setiformis. S. jug a Us. 24. 25- S. fluviatilis. Chromatophores 3, rarely 2 ; plant of brackish water. 10. 5". deciinina var. snbmarina. 25. 25. 26 26 27. 27. 28 28 29. 29. S. ternata. 26. ii. .S". nitida. S. parvispora. 28. 34- 5. protecta,. 29. 5". Weberi. 30. 30 30 31. 31. 32 32 32 33. Cells 50-65 /j. diam. 23 Cells 70-78 fj. diam. Spore 60-72 /u diam. Spore about 50 /x diam. 14. Chromatophore single. Chromatophores two or more. , Spore membrane punctate. 37 Spore membrane smooth. Fertile cells little if any swollen. 3: Fertile cells distinctly swollen. , Filaments 9-23 /a diam. . Filaments 24-33 <"• diam. Inflation cylindrical. 34. Inflation rounded or tapering at the ends. . Cells 9-12 fj. diam. ; 4-15 times as long. 3-8 times as long. 10-25 times as long, fertile cells quadrately swollen. 31. S. quadrata diam. ; fertile cells somewhat rounded. 33. 5. Grevilleana Cells 30-33 M diam. ; chromatophores broad. 35. .S". Hassallii Cells 39-42 fj. diam. ; chromatophores slender. 36. S. insignis Cells 15-18 /i diam. Cells 18-21 p diam. Cells 24-30 fj. diam. 33- S. groenlandica. 32- 28. S. tenuissima. 29. S. inflata. 30. S. Spreeiana. 33. Cells 28-33 34 34 Subgenus EUSPIROGYRA ; conjugation by means of a tube. Section CONJUGATA ; dissepiments plane. Subsection DIPLOZYGA ; each cell emitting a tube. i. S. L.ONGATA (Vauch.) Kiitzing, 1843, p. 279; Petit, 1880, p. 20, PI. V, figs. 4 & 5; Wolle, 1887, p. 214, PI. CXXXV, figs. 9 & 10 ; P. B.-A., No. 510. Filaments 20-36^ diam., cells 2-10 diam. long, chromatophore single, broad, bright green, making 2-5 turns in the cell; fertile cells not swollen ; spores broadly ovoid with rounded ends, pale yellow at maturity, twice as long as broad, entirely filling the width of the cell. Mass., R. I., N. J., Colorado. Europe, So. America. The perfectly cylindrical form of the fertile cells, barely large io8 TUFTS COLLEGE STUDIES, VOL. II, No. 3 enough to contain the spores, distinguishes this species from others of the same general dimensions. 2. S. PORTICALIS (Miiller) Cleve, 1868, p. 22, PI. V, figs. 8-13 ; Petit, 1880, p. 21, PI. V, figs. 8-12; P. B.-A., No. 365; 5. qidnina Wolle, 1887, p. 213, PI. CXXXIV, figs. 14-17. Filaments 30-48 fj. diani., cells 2-6 diam. long; chromatophore single, quite broad, dentate, bright green, making 3-4 turns in the cell ; fertile cells little or not at all swollen ; spores ovoid or subglobular, yellowish at maturity, i}4 diani. long; diam. up to 42 /j.. Mass., N. J., Pa., Iowa, Cal. Europe, Asia, So. America. A very common species, often forming extensive yellow-green masses in quiet water ; very mucilaginous ; the broad, dentate spiral, with many brilliant pyrenoids, is characteristic. Forma MINTOR Collins, P. B.-A., No. 1263. Filaments about 42 /w. diam. ; spores 30-35 fj. diam. Conn. 3. S. JUERGENSII Kutzing, 1845, p. 222 ; Petit, 1880, p. 16, PI. V, figs. 6 & 7 ; Wolle, 1887, p. 213, PI. CXLJI, figs 3 & 4: Rabenhorst, Algen, No. 1534. Filaments 24-26 /j. diam. ; cells 2/4-5 diam. long ; chromatophore single, slender, delicate green, with pyrenoids much broader than the spiral ; fertile cells slightly swollen, but no more than caused by the spores ; spores 30 /A diam., ellipsoid, twice as long as broad, golden color at maturity. Cal. ; according to Wolle, generally distributed. Europe . Nearly allied to 6". porticalis and .5". communis ; differing from the former by smaller dimensions throughout : from the latter by the different chromatophore, and by the shorter and stouter spore. 4. S. CATEXAEFORMIS (Hass.) Kiitzing, 1849, P- 43s : Petit, 1880, p. 17, PI. Ill, figs. 9-12; P. B.-A, No. 361. Filaments 24-27 /Ji diam., cells 2-5T2 diam. long; chromatophore single, quite broad, dentate, making 1-6 turns in the cell ; fruiting cell swollen, up to 36 /u diam. ; spores ellipsoid writh rounded ends, yellowish at maturity, 2-2J2 times as long as broad, up to 30 p. diam. Mass., Cal. Europe. A quite variable species, but not difficult of recognition b)r the combination of characters just given. 5. S. VARIANS (Hass.) Kiitzing, 1849, p. 439; Petit, 1880, p. 19, PI. IV, figs. i-8; Wolle, 1887, p. 212, PI. CXXXIV, figs. 8-13 ; P. B.-A., Nos. 367, 962. Filaments 33-40 p. diam., cells 2-3 diam. long ; chromatophore single, quite broad, den- THE GREEN AI^GAE OF NORTH AMERICA 109 tate or serrate, making 1-3 turns in the cell ; fertile cells swollen only on the side of the conjugation ; cells in filament which have not conjugated often much swollen and distorted; spores ovoid or ellipsoid, 1^-2}^ diam. long ; diam. 33-38 ^. Me., Mass., N. Y., N. J., Iowa, Wash., Cal. Europe, So. America. A polymorphous species, but no other species of about the same dimensions has the unilaterally inflated cells, and the ir- regularly inflated vegetative cells. 6. S. FUSCO-ATRA Rabenliorst, Algen, No. 98 ; Wolle, 1887, p. 215, PL CXIy, figs. 4-7. Filaments 40-45 ^ diam., cells 2-4 diam. long ; cylindrical or slightly constricted at the nodes ; becoming blackish with age, and purplish in the dried speci- men ; chromatophore single, making 2-3 turns in the cell : spores polymorphous, globose, ellipsoid, oblong or cylindrical, 40-47 /J. diam. Pa. Europe. This species is included with some doubt ; the description b)^ Wolle is meager and the plate little more satisfactory ; no other American record is known. No mention is made of the black- ish or purplish brown color at maturity, from which it has its name, and neither plate nor description indicates the collapsed cells surrounding the ripe spores. The two-spired filament in the figure is also suspicious. 7. S. COMMUNIS (Hass.) Kiitzing, 1849, p. 439; Petit, 1880, p. 16, PI. V, figs. 1-3 ; Wolle, 1887, p. 213, PI. CXLII, figs, i and 2; P. B.-A., No. 1416. Filaments 20-25 /*diam., cells 3-5 diam. long; chromatophore single, quite slender, making i1.-- | turns in the cell ; fertile cells not at all swollen ; spores ellipsoid with pointed ends, yellowish at maturity, 19-23 /A diam., 2-3 times as long. Mass., N. J. Europe, So. America. Often forming dense masses of dark green color in quiet water ; soft to the touch but not mucilaginous ; best character- ized by the uninflated fertile cells and by the long spores with pointed ends. 8. S. CONDENSATA (Vauch.) Kiitzing, 1843, p. 279; Petit, iSSo, p. 22, PI. IX, figs. 6-8; Wolle, 1887, p. 215; Wittr. and Nordst., Alg. Exsicc., No. 247. Filaments 48-54 ^ diam., cells as long as broad, or slightly longer or shorter ; chromato- phore single, slender, with large pyrenoids making 1-^-i)4 turns in the cell ; fertile cell not inflated; spores ellipsoid, \yz diam. long, up to 36 ^ diam., conjugation usually lateral. So. A in erica. no TUFTS COLLEGE STUDIES, VOL. II, No. 3 Var. RUSBYI Wolle, 1887, p. 215, PL CXXXIX, figs. 7-9. Filaments 62-75 /A diam. ; otherwise like the type. New Mex., N. J.? It is not clear from Wolle's account whether he had observed the type in this country, or only the var. Rusbyi. The N. J. reference is in any case doubtful, only sterile plants having been observed. 9. S. SUBSALSA Kiitzing, 1845, p. 222 ; Wolle, 1887, p. 212, PI. CXLI, figs. 3 and 4. Filaments 22-25 P- diam., cells i-i}4 diam. long; chromatophore single, making 1^-3 turns in the cell ; fertile cells little or not at all swollen ; spore ovoid, slightly longer than the diam.; diam. 18-20 /x. Florida. Europe. Included with some doubt ; the locality is not indicated as brackish. 10. S. DECIMINA (Miiller) Ktitzing, 1843, p. 279; Petit, 1880, p. 25, PI. VIII, figs. 1-3; Wolle, 1887, p. 216, PI. CXXXV, figs. 5 and 6; Wittr. and Nordst., Alg, Exsicc., No. 1372. Filaments 34-40 //. diam., cells 2-4 diam. long; chromatophores 2, rarely 3, quite broad, making 1-2 turns in the cell ; fertile cells not swollen ; spores broadly ovoid or almost globular, 38X42-75 ^, as broad as the filament. Mass., Pa., Iowa, Jamaica, St. Croix. Europe, Africa. Rather common ; usually occurring in large masses, very mucilaginous. Var. TRIPLICATA Collins, P. B.-A., No. 960. 'Chromato- phores uniformly three ; spores 34-48X48-54^; otherwise like the type. Mass., Cal. Var. Submarina n. var. Filaments 27-32 ^ diam., cells 3-6 diam. long; chromatophores 2 or 3, making 1^2-3 turns in the cell; spores ellipsoid, 2-3 diam. long, 31-37X56-120 /A ; fertile cells swollen just enough to hold the spore. Mass., Conn. Perhaps a good species, but having so many resemblances to 5". dccimina as to indicate that the differences may be due to the station, salt marsh and brackish pools, an unusual one for a Spirogyra. The principal distinctions are in the slender fila- ments, longer cells, longer spores and somewhat swollen fertile cells. n. S. NITIDA (Dillw.) Link, 1833, p. 262; Petit, 1880, p. 28, PI. X, figs. 6-10 ; Wolle, 1887, p. 217, PI. CXXXVII, figs. 7 and 8; P. B.-A., No 513. Filaments 72-78 ^ diam., cells i,],j-3 diam. long ; chromatophores usually 5, more or less THE GREEN ALGAE OF NORTH AMERICA m broad, sometimes straight and parallel, sometimes making a single turn in the cell ; fertile cells little or not at all swollen ; spores ellipsoid with tapering ends, yellowish at maturity, 1)2-2 diam. long, diam. 60-72 /u. Mass., Conn., N. J., Iowa, Cuba. Europe, Africa. Forms dark green, very mucilaginous masses ; filaments crisp and shining, when taken from the water. 6\ diluta Wood, 1872, p. 170, PI. XV, fig. 2, should probably be included in this species. 12. S. JUGAUS (Fl. Dan.) Kiitzing, 1845, p. 223; Petit, 1880, p. 28, PI. XI, figs. 3 and 4; Wolle, 1887, p. 219, PI. CXXXVIII, figs. 7 and 8 ; Rabenhorst, Algen, No. 1049. Filaments 90-100 p. diam. at the nodes, cells i-i:j diam. long, usually swollen near the middle and there reaching 115 fj. diam., chromatophores 3 or 4, quite broad, pale green, finely dentate, with many large pyrenoids, and making 1-2 turns in the cell ; fertile cells of the same form ; spores ovoid, brown at maturity, \Y-z diam. long, diam. IOO-IIO/A. Mass. Europe. Not uncommon, forming dense masses of a handsome green, hardly at all mucilaginous ; filaments firm and crisped, large enough to be visible singly. The swollen vegetative cells give the most striking character. 13. S. SETIFORMIS (Roth) Kiitzing, 1845, P- 223 : Petit, 1880, p. 29, PI. XI, figs, i & 2; Wolle, 1887, p. 219, PL CXXXVIII, figs. 1-4; Wittr. & Nordst., Alg. Exsicc., No. 747. Filaments 100-1 10 p. diam., cells about as long as broad, sometimes nearly 2 diam. long; 4 rather broad chromatophores, irregular, with sinuate margins and many large pyrenoids, making *4-i turn in the cell; fertile cells not swollen; spores ellipsoid, diam. 96-100 /u,. Mass., Pa., N. J. Europe. Quite near .5T. jugaiis, but without the swollen vegetative cells, with narrower and more irregular spirals, and somewhat smaller spore. 14. S. PARVISPORA Wood, 1869, p. 139; 1872, p. 169, PL XV, fig. 7 ; Wolle, 1887, p. 221, PL CXL, figs. 8 & 9. Fila- ments about 75 /A diam., cells 2-4 diam. long; chromatophores 4, narrow, making i1,- turns in the cell; fertile cells not swollen; spores ellipsoid, about 1^2-2 diam. long, diam. about 50^.. Florida. Quite distinct by the small size of the spores in proportion to the cells. There appears to be no record of it but the original description. ii2 TUFTS COLLEGE STUDIES, VOL. II, No. 3 15. S. ORTHOSPIRA Nageli in Kiitzing, 1849, p. 441 ; Petit, 1880, p. 30, PI. X, figs. 4 and 5 ; Wolle, 1887, p. 218, PI. CXXXVI, figs. 10-11; S. majusacla P. B.-A., No. 511. Fila- ments 60-66 /LI diam., cells 2-3 diam. long ; chromatophores 7 or 8, very slender, pale green, usually straight and parallel, some- times inclined and making a quarter turn in the cell ; fertile cells little or not at all swollen ; spores at maturity brown, len- ticular, about 72 /j. diam., by 48 /A thick. Mass., N. Y., Pa., Minn., Dakota. Europe, So. America. Usually in scattered filaments among other algae ; while in each of its characters it resembles some other species, there is no one which combines the characters of numerous, slender, straight or nearly straight chromatophores, and lenticular spores, not over 72 ^ diam. As No. 285 of Tilden, American Algae, is distributed, under the name of 6*. majuscula var. brachy- mcrcs, a plant agreeing with 6". orthospira, except that the cells are somewhat larger. No spores were found in the specimen examined, and it seems safer to include it under the type of the species. 16. S. MAXIMA (Hass.) Wittrock, 1882, p. 57; Wolle, 1887, p. 218, PL CXXXIX, figs. 3 and 4; P. B.-A., No. 512; S. oi-biculai-is Petit, 1880, p. 31, PI. XII, figs, i and 2; P. B.-A., No. 1018. Filaments 130-140 /A diam., occasionally as low- as 118 fj. ; cells as long as the diam. or slightly more or less ; chro- matophores 6 or 7, narrow, pale, very finely dentate, with large pyrenoids, making half or three-quarters of a turn in a cell ; fer- tile cells not swollen ; spores lenticular, brown at maturity, about 100-115 fji diam., by 77-84 //. thick. Pa., Cal. l^uropc, So. America. The size of the filaments given above is the usual dimension, but considerably larger or smaller are found, in exceptional cases ; the American specimens seem to be usually smaller than the European. Var. INAEOUALIS Wolle in Wittr. and Nordst., Alg. Exsicc., No. 541 ; 1887, p. 218, PI. CXXXVIII, figs. 5 and 6. Sporif- erous filaments about So p. diam., conjugating with filaments about 125 fj- diam., spores not wider than the cells in which they occur. Pa. Wittrock and Nordstedt suggest, Fasc. 21, p. 31, that this is possibly a hybridization of two species. 17. vS. CRASSA Kiitzing, 1843, p. 280, PI. XIV, fig. 4; THE GREEN ALGAE OP NORTH AMERICA 113 Petit, iSSo, p. 32, PI. XII, figs. 3 and 4; Wolle, 1887, p. 219, PI. CL,X, figs. 1-3; Phyk. Univ., No. 440. Filaments 150-160 /A diain., cells 1-2 diani. long ; chroma tophores numerous, rarely as few as 4, often 10 ; not parallel, rather slender, sinuate at the margin, with very small pyrenoids, making y2-i turn in the cell, or sometimes nearly straight ; fertile cells not swollen ; spores broadly ovoid and flattened, about i^ diam. long, diam. 140-150 /A. Mass., Pa., N. J., Iowa. Europe, So. America. The largest species of the genus, the individual filaments quite distinct to the eye, firm and crisped, somewhat mucilagi- nous. 18. S. AFFINIS (Hass.) Petit, 1880, p. 18, PI. Ill, figs. 13-14 ; P. B.-A., No. 959. Filaments 27-30 /A diam., cells 1^-3 diam. long; chromatophore single, quite slender, making 1-3^ turns in the cell, often forming only a single ring; fertile cells much swollen, often nearly or quite spherical ; spores ellipsoid, 1-1^2 diam. long, up to 30 /A diam. Lateral conjugation more common than scalariform. Jamaica, Alaska. Europe. Quite distinct by the uniformly short vegetative cells, and the bullate fertile cells. 19. S. MIRABILIS (Hass.) Ku'tzing, 1849, p. 438; Petit, 1880, p. 14, PI. Ill, figs. 3 and 4; Wolle, 1887, p. 211, PI. CXXXIV, figs, i and 2; Wittr. and Nordst., Alg. Exsicc., No. 1377. Filaments 24-27 ^ diam., cells 4-10 diam. long; chromatophore single, quite broad, making 4-7 turns in the cell ; fertile cells swollen, even before the formation of the spores, which are ovoid or ellipsoid, 24-26 /u, diam., il/>-2 diam. long ; and are formed without any observable conjugation, either lateral or scalariform. Maine, Wis. Europe, Asia. The spores of this species, though in appearance like zygo- spores, are more properly to be considered aplanospores. 20. S. FLAVESCENS (Hass.) Kiitzing, 1849, p. 438 ; Petit, 1880, p. 15, PI. HI, figs. 5 and 6; Wolle, 1887, p. 211, PI. CXXXIV, figs. 3 and 4 ; Rabenhorst, Algen Sachsens, No. 60. Filaments 11-13 /A diam., cells 3-4 diam. long; chromatophore single, quite broad, yellowish green, making 1-2 turns in the cell ; fertile cells swollen ; spores ovoid with rounded ends, yel- lowish when mature, 20 /A diam., i ^ diam. long. Florida. Europe. Possibly only a variety of the following species, from which it differs chiefly in its smaller diameter, and in the different form of the fertile cells. Wolle gives a larger diameter for the fila- ii4 TUFTS COLLEGE STUDIES, VOL. II, No. 3 ments than that noted above ; his plant seems intermediate be- tween S. flavescens and 5". gracilis. 21. S. GRACILIS (Hass.) Kiitzing, 1849, p. 438 ; Petit, 1880, p. 15, PI. Ill, figs. 7 and 8 ; Wolle, 1887, p. 211, PI. CXXXIV, fi»s- 5~7> P- B.-A., No. 1418. Filaments 1 8-2 1 /A diam.; cells 3-5 diam. long ; chroniatophore single, quite broad, rich green, making ^-3 turns in the cell ; fertile cells swollen only on the conjugating side, the other remaining straight ; spores ovoid, yellowish at maturity, diam. about 30 /j., length about double. Mass., Michigan. Europe. 22. S. LUTETIANA Petit, 1879, p. 97, PI. VI; 1880, p. 21, PI. IV, figs. 9-13; Wolle, 1887, p. 214, PL CXXXV, figs. 7 and 8 ; P. B.-A., No. 1065. Filaments 30-36 ^ diam., cells 3-7 diam. long ; chroniatophore single, broad, dentate, dark green, making 3-7 turns in the cell ; fertile cells sometimes swollen, sometimes cylindrical ; spores polymorphous, globular, ellipsoid, oblong, cylindric-ellipsoid, pyriform or reniform ; yellowish at maturity, 2-4 diam. long; diam. 30-43^. Mass., Washington, Florida ? Europe. The most distinctive character of this species is found in the polymorphous spores. Wolle's description of the Florida plant leaves considerable doubt as to its identity with Petit's species. 23. S. TERXATA Ripart, 1876, p. 162 ; Petit, 1880, p. 26, PI. VIII, figs. 4-7 ; Tilden, American Algae, No. 159, as 6". neglecta. Filaments 50-65 /j. diam., cells 1^2-2 diam. long, somewhat swollen at the middle ; chromatophores three, narrow, with apparent middle line uniting the pyrenoids, making 1)2-2 turns in the cell ; fertile cells swollen and shortened, often shorter than the diam., so that the spores are turned at right angles to their usual position ; spores ovoid, 45-66 //. diam., 1-1^2 diam. long. 111., Colorado. Europe. This species is nearly allied to S. neglecta, but the cells are shorter, especially the fertile cells, and the spores are often so closely set that the}- are side by side, their longer axes at right angles to the direction of the filament. 24. S. FLUVIATILIS Hilse in Rabenhorst, Algen, No. 1476 ; Petit, 1880, p. 27, PI. V, fig. 13; Wolle, 1887, p. 216, PI. CXXXVI, figs. 1-3; P. B.-A., Nos. 1217, 1417. Filaments 36 ju diam., cells 5-6 diam. long; chromatophores 4, slender, very pale green, making 1^2-2^2 turns in the cell : fertile cells swollen and shortened; spores ovoid, about 50 So /x. Mass., Pa. Europe. No spores have been reported from the European localities, THE GREEN ALGAE OF NORTH AMERICA 115 and Wolle's statement as to Pennsylvania localities was the first record for spores of this species ; in Massachusetts it was found sterile, attached to stones, also floating, with spores like those figured by Wolle. 25. S. BELUS (Hass.) Cleve, 1868, p. 18, PI. Ill, figs. 2-5 ; Petit, 1880, p. 31, PL X, figs. 1-3; Wolle, 1887, p. 217, PI. CXXXVII, figs. 5 and 6 ; PI. CXXXIX, figs, i and 2 ; P. B.-A., No. 359. Filaments 65-80 //, diam., cells 1^2-3 diam. long ; chromatophores 5 or 6, narrow, with large prominent py- renoids ; almost straight, or making half to three-quarters of a turn in a cell ; fertile cells swollen and shortened ; swelling sometimes only on the side opposite to the conjugation ; spores brown at maturity, lenticular, diam. 84-90 fj., thickness 55-60 p.. Mass., N. J., Pa. Europe. 26. S. DUBIA Kiitzing, 18553, p. 8, PI. XXIV, fig. 4; Wolle, 1887, p. 220, PL CXXXV, figs, n and 12. Filaments 43-50 /j. diam., cells 1^2-2^2 diam. long; chromatophores 2, rarely 3, narrow, making 1-3 turns in the cell ; fertile cells slightly swollen ; spores brownish at maturity, ovoid-ellipsoid, about 40 /i diam., 1-2 diam. long. Mass., Pa. Europe. Var. LONGIARTICULATA Kiitzing, 18553, p. 8, PL XXV, fig. i ; Wolle, 1887, p. 220; P. B.-A., No. 961. Cells 5 diam. long; chromatophores 2 or 3. British Columbia. Europe. Subsection MONOZYGA ; only one cell emitting a tube. 27. S. PUNCTATA Cleve, 1868, p. 23, PL VI, figs. 1-4; Petit, 1880, p. 24, PL IX, figs. 9-n ; Wolle, 1887, p. 215, PL CXLI, figs- 5'7- Filaments 24-27 ^ diam., cells 6-12 diam. long; chromatophore single, rather slender, with few pyrenoids, mak- ing 4-7 turns in the cell ; fertile cells swollen and shortened ; tube issuing from only one of the conjugating cells, broadening until it reaches the surface of the other cell ; spores ellipsoid, yellowish at maturity, 1^2-2 diam. long, about 36 //. diam.; median membrane finely punctate. N. J. Europe, Asia. The punctate membrane and the peculiar formation of the tubes amply distinguish this from all our other species. The latter character shows a more distinct sexual differentiation than in other species of the genus. Section 2. SALMACIS ; Dissepiments replicate. 28. S. TENUisstMA (Hass.) Kiitzing, 1849, p. 437; Petit, 1880, p. 6, PL I, figs. 1-3; Wolle, 1887, p. 207, PL CXXXII, figs. 1-3; P. B:-A., No. 456. Filaments 9-12 ^ diam., cells 4-12 diam. long; chromatophore single, slender, making 3-5^2 n6 TUFTS COLLEGE STUDIES, VOL. II, No. 3 turns iu the cell ; fertile cells much swollen, vesicular, not shortened, extreme diam. 37-42 p. ; spores ellipsoid, yellow at maturity, 2 diam. long, diam. about 30 /A. Mass., R. I. Eiirope, New Zealand. The smallest of our species and easily recognized. 29. S. INFLATA (Vauch.) Kiitzing, 1843, p. 279; Petit, 1880, p. 7, PL I, figs. 4-6 ; Wolle, 1887, p. 207, PI. CXXXII, figs. 6 and 7; P. B.-A., No. 363. Filaments 15-18 /A diam., cells 3-8 diam. long ; chromatophore single, quite broad, making 3-8 turns in the cell ; fertile cells much swollen, somewhat shortened, 42-48 i*. diam.; spores ellipsoid, dark yellow at maturity, 2 diam. long, diam. 30-36 p. Mass., Conn., N. J. Europe. Resembles .5". temtissima, but larger, with broader and more densely twisted spiral. 30. S. SPREEIANA Rabenhorst, Algen, No. 988; Petit, 1880, p. 7, PI. I, figs. 7-9 ; Wolle, 1887, p. 208, PI. CXXXII, figs. 4 and 5; P. B.-A., No. 1019. Filaments 18-21 /u, diam., cells 10-25 diam. long; chromatophore single, slender, making 1^-4 turns in the cell ; fertile cells swollen, not shortened, 30-42 /A diam.; spores ellipsoid, yellowish at maturity, 2-3 diam. long, diam. up to 36 p. Mass., Washington, Cal. Europe. The very long cells, with a loose, almost inconspicuous spiral, the swelling in the fertile cells tapering to each end of the cellr sufficiently distinguish this species. 31. S. OUADRATA (Hass.) Petit, 1874, p. 41, PI. I, fig. 2; 1880, p. 8, PL I, fig. 13; Wolle, 1887, p. 208, PL CXXXII, figs. S-io; P. B.-A., No. 366. 5". bifaria (Bailey) Kiitzing, i855a, p. 7, PL XXI, fig. 3. Filaments 24-27 /u, diam., cells 3-9 diam. long; chromatophore single, broad, making 1^2-5 turns in the cell ; fertile cell much swollen, up to 54 ^ diam., appear- ing like a rectangle with rounded corners ; spores ellipsoid or cylindric-ellipsoid, brown at maturity, 1^2-2 diam. long, diam. 42-48 /j.. Mass., N. Y., Pa. Europe. Easily recognizable by the peculiar shape of the fertile cells. According to Wolle, S. pulchella Wood, 1872, p. 164, PI. XIV, fig. 2, is a synonym of this species. The plate, though appar- ently not very characteristic, does not contradict this conclu- sion. Zygnema bifaria Bailey, from examination of authentic specimens, agrees fully with .5". quadrata. 32. S. WEBERI Kiitziug, 1843, p. 279 ; Petit, 1880, p. 9, PL I, figs. 10-12; Wolle, 1887, p. 208, PL CXXXII, fig. u ; P. B.-A., No. 368. Filaments 22-28 /A diam., cells 6-16 diam. long; THE GREEN ALGAE OF NORTH AMERICA 117 chromatophore single, slender and loose, with large pyreuoids, making 3/^-6 turns in the cell ; fertile cells not swollen, or only enough to contain the spores, which are ovoid, 1^-2 diam. long, diam. 26-30 ft. Mass., N. Y., N. J., Pa. Europe. From 6". Grei'illeana, which this species considerably re- sembles, it is distinguished by never having more than one spiral, and b}r cells little if at all swollen. 33. S. GREVILLEANA (Hass.) Kiitzing, 1849, p. 438; Petit, 1880, p. 10, PI. II, figs. 1-5 ; Wolle, 1887, p. 209, PI. CXXXII, figs. 12-13; P- B.-A., No. 362. Filaments 28-33 M diam., cells 3-10 diam. long ; chromatophore broad, usually single but occasionally two in scattered cells, making 4-5, sometimes 6-9 turns in the cell ; fertile cells much swollen ; spores ovoid with rounded ends, yellowish at maturity, 2-2^2 diam. long, diam. 30-36 p. Mass., N. J., Iowa. Europe. Often forming extensive masses, of a bright green color and lubricous. To be distinguished carefully from 5". Weberi, as noted under that species. 34. S. GROENLANDICA Rosenvinge, 1883, p. 37, PI. VII. Filaments 18-23 /* diam., cells 18-28 diam. long; chromato- phore single, making 3-8 turns in the cell ; fertile cells swollen in the middle, the swollen part cylindrical or sub-cylindrical, one-third to one-fourth the total cell length ; spores ellipsoid, 34-38X100-130 fj., dark brown; conjugation lateral; partheno- spores occurring in unswollen cells, the spores elongate, but of more or less irregular form, nearly as large in diam. as the cell. Greenland, Mass. Resembling somewhat .5". quadrata and .S". Spreeiana ; from the former it differs by the much longer cells, the swelling occupy- ing only a small part of the whole length ; from the latter by the swelling being sharply marked off from the unswollen part of the cell, and also by the color of the spore, dark brown at maturity instead of yellow. 35. S. HASSALUI (Jenner) Petit, 1880, p. 12, PI. II, figs. 6-8; Wolle, 1887, p. 210, PL CXXXIII, figs. 5-7; Phyk. Univ., No. 732. Filaments 30-35 /u, diam., cells 4-8 diam. long ; chromatophores 2, quite broad and loose, making 1^-2 turns in the cell; fertile cells slightly swollen; spores ellipsoid, 1^-3 diam. long, diam. 42-48 /a, yellow at maturity. Mass., Iowa. Europe. 36. S. INSIGNIS (Hass.) Kiitzing, 1849, p. 438; Petit, 1880, p. 13, PL III, figs i & 2; Wolle, 1887, p. 210, PL CXXXIII, n8 TUFTS COLLEGE STUDIES, VOL. II, No. 3 figs. 8 & 9 ; Wittr. & Nordst., Alg. Exsicc., Nos. 958, 1373. Filaments 38-45 /j. diam., cells 4-12 diam. long ; chrotnatophores 3, very slender, pale green, with large pyrenoids, making }4-i}4 turns in the cell ; fertile cells much swollen and shortened ; spores. ellipsoid, 1^2-3 diam. long, diam. up to 48 p.. N. J., Pa. Europe. Our only species with replicate cell walls and three spirals ; the typical form quite distinct, but connected with 5*. Hassallii by the following variety. Var. HANTZSCHII (Rab.) Petit, iSSo, p. 13; S. Hantzschii Wolle, 1887, p. 211, PI. CXXXIII, figs. lo-u ; P. B.-A., No. 364. Chromatophores usually 2, occasionally 3. Mass., Pa. Europe. Petit notes that in the conjugation in this variety, filaments with two spirals frequently unite with filaments of three spirals ; in this case the three spiral cells always function as female, receiving the contents of the two spiral cells and developing the spore. 37. S. PROTECTA Wood, 1872, p. 165, PL XIV, fig. 3; 5. elegans Cleve in Wittrock, 1868, p. 190; 6". calospora forma gracilior Cleve, 1868, p. 26, PI. VIII, figs. 2 and 3 ; .S". calospora Petit, 1880, p. u, PI. II, figs. 11-13; Wolle, 1887, p. 209, PI. CXXXIII, figs. 3 and 4; P. B.-A., No. 360. Filaments 32-36 /x diam., cell's 6-12 diam. long; chromatophore single, slender and loose, making 4-5 turns in the cell ; fertile cells little or not at all swollen, not over 42 //, diam.; spores ellipsoid or cylindric- ellipsoid with rounded ends, yellow at maturity, 2-3 diam. long, diam. 40-42 /u. ; median membrane punctate. Fig. 8. Mass., Conn., N. J., Mich. Europe. The only species occurring with us which has the replicate cell walls and the punctate membrane. It is a beautiful object under the microscope, the yellow spores with their elegant mar- gin standing out strongly against the dark green filaments. In Cleve's description of ^. calospora two forms are distin- guished ; forma a major, forma b gracilior ; afterwards the sec- ond form was raised to specific rank as .5". elegans, but this name cannot stand as there is an earlier ^". elegans Bonhome, 1858, p. 6. The genuine 5". calospora, S. calospora forma major of the original description, appears to be unknown outside of Scandi- navia, but 5". protecta seems common in this country as well as in various parts of Europe. Wittrock considers .S*. elegans to be the same as Vaucher's Conjugata longata, but the evidence THE GREEN ALGAE OF NORTH AMERICA 119 seems hardly sufficient to justify transferring the name to this species, from the so long recognized .S1. longata Ku'tz. Subgenus SIROGOXIUM. Cells directly conjugating, without formation of tube. 38. S. STICTICA (Eng. Bot.) Wille, 1884, p. 34 ; P.B.-A.,No. 1366 ; Sirogonium sticticnm Petit, 1880, p. 34, PI. VII, figs. 6-8; Wolle, 1887, p. 222, PI. CXU, figs. 8-io. Filaments 38-54 /* diam., cells 2-4 diam. long ; chromatophores 3-4, narrow, paral- lel and straight or slightly curved ; fertile cells shortened but only verj' slightly swollen ; conjugation of cells direct, by gen- icular bending towards each other of two filaments, the female filament larger than the male ; each of the original filament cells dividing into two, rarely three in the male filament ; of these cells two, one from each filament, unite to form the spore, the others remaining sterile ; spores ellipsoid, yellowish at maturity, i^ diam. long, up to 60 /x diam. Florida, Cal. So. America, Europe. Though this plant has long been kept as a distinct genus, its inclusion in Spirogyra seems justified by an intermediate form, Sirogonium ceylanicum Wittr. It is amply distinQt from any other American species by the combination of characters, linear slightly spiral chromatophores and conjugation without forma- tion of tubes. Doubtful species of Spirogyra. S. negleda Wolle, 1887, p. 216. ^S". subaeqita Wolle, 1887, p. 217; appears to belong under S. bell is. S. rivularis Wolle, 1887, p. 220; the figures in PI. CXXXVI do not agree with the descriptions of other authors. 5. adnata Wolle, 1887, p. 220, PL CXXXV, figs. 3 and 4, seems indistinguishable from 5". derimina. S. elongata Wolle, 1887, p. 221, refers to PI. CXXXV, figs. i and 2, but in the volume of plates these figures are indicated as .S. insignis var. elongata ; the dimensions of the figures agree best with 5". elongata, but under the circumstances it is uncer- tain just what Wolle's plant was. 5". elongata Wood, 1872, p. 164, PI. XIV, fig. i is 5. tenuissima (Hass.) Kiitz. 3. DEBARYA Wittrock, 1872, p. 35. Cells cylindrical, about 5 times as long as broad ; dissepi- ments even ; chromatophore an axillary plate with several pyre- noids ; conjugation between two filaments not differing in 120 TUFTS COLLEGE STUDIES, VOL. II, No. 3 appearance; zygospore formed in the tube, with smooth, sac- cate, 3Tellowish, translucent outer membrane, and browish-yellow median membrane, with three longitudinal parallel ridges, con- nected by fine, radial cross lines. D. GLYPTOSPERMA (De Bary) Wittrock, 1872, p. 35; P. B.-A., No. 1419. Mougeotia glyptosperma De Bary, 1858, p. 78, PL VIII, figs. 20-25; Wolle, 1887, p. 229, PI. CXL,VI, figs. 6-9. Filaments crisped, lubricous, 10-15 P- diam.; cells 6-12 diam. long ; fertile cells still longer ; spores ovoid, 42-49 ) ; 30-40 p. Fig. 9. Mass., Minn., Florida. Europe, New Zealand. The peculiarly striate spores, ovoid, set lengthwise of the tube, 'occupying the whole space between the filaments, dis- tinctly characterize this species. 4. ZYGOGONIUM Kiitzing, 1843, p. 280. Cells cylindrical, as long as broad to twice as long ; dissepi- ments even ; two axillary, irregular chromatophores, each with one pyrenoid ; zygospore formed in the tube between two cells not differing in appearance ; the prolongation from each cell cut off from the rest of the cell by a wall, before uniting with the prolongation from the other cell ; akinetes sometimes formed, as in Zygncma. The protoplasm that is to take part in the formation of the zygospore gathers at the newly formed tube, and is cut off from the mother cell ; then the wall at the end of the tube is dissolved where it touches the tube from the other cell, and the two recently formed small cells unite to form the spore. In Zygncma the spore is formed in a tube which still communicates with both the filament cells. This is practically the only difference between the genera, though the chromatophore is less regularly star-shaped in Zygogonium than in Zygnema. Z. ERICETORUM Kiitzing, 1845, p. 224; Z. Agardhii Wolle, 1887, p. 226, PI. CXL,V, figs. 6 and 7. Filaments 15-25 //, diam., cells 1-4 diam. long, greenish, becoming brownish, pur- plish, or blackish by exposure to air and sun ; spores globose to ovoid, 20-25 /u. diam. Fig. 10. Var. TERRESTRE Wittr. and Nordst., Alg. Exsicc., No. 1594 ; P. B.-A., No. 519. Color more uniformly purple or violet ; cells somewhat constricted at the nodes ; often with short rhizoidal branches ; wall thicker and stouter ; seldom fruiting. On moist ground. Both type and variety, Maine, Mass., Florida. Europe, So. America. THE GREEN ALGAE OF NORTH AMERICA 121 The peculiar mode of producing the zygospores places this species in a separate genus from forms like Zygnema pectinatum, which it otherwise much resembles. Zygnema Ralfsii Wolle, 1887, p. 227, appears to be a doubtful determination, and the specimens on which it is based might prove to belong to this species. Of Z. aequale Wolle says "we assume the name at a hazard " ; and of Z. parvulum " we quote it without confidence in its value" ; these names need hardly be retained. Z. pur- pureum Wolle, 1887, p. 224, is very incompletely described; neither from text or plate can be learned the form of the chrorna- tophores, nor the character of the membrane ; dimensions also are uncertain, and until further evidence it must be classed as doubtful. Family 2. MKSOCARPACEAE. Cells cylindrical, always several times as long as broad, united in unbranched filaments, rarely having short, rhizoidal branches. Chomatophore an axile plate with several pyrenoids ; nucleus at the middle of the plate. Conjugation between either two cells of the same filament or cells of two filaments. Part of the protoplasm separates from the rest in the cell ; the part so separating unites with a similar part from the other cell, to form the zj'gospore, which is either entirely in the tube con- necting the cells, or extends somewhat into one or both cells ; spore varying in form, but usually lentiform, with round or four- or six-angled outline ; outer membrane of spore colored yellow or brown, smooth or variously sculptured. Partheno- spores, akinetes, and aplanospores sometimes occur, much as in the Zygnemaceae. Only two genera of Mesocarpaceae are now recognized, Gona- toncma with two species, and the large genus Mougeotia, includ- ing the former genera Mesocarpus, Crater ospermum> Pla^iosper- >n inn, Staurospermum and Sphaerosperm i/in. The distinctions as to shape and surroundings of the spore, on which these genera were founded, have been proved to be uncertain, the types characteristic of the different genera sometimes occurring on the same plant. KEY TO THE GENERA OF MESOCARPACEAE. Aplanospores with double membrane formed in the middle part of a cell, shutting off the remainder of the cell by a wall. Conjugation un- known. 2. GONATONEM A. Zygospores formed as described for the family; aplanospores excep- tional, i. MOUGEOTIA. 122 TUFTS COLLEGE STUDIES, VOL. II, No. 3 i. MOUGEOTIA Agardh, 1824, p. XXVI. Cells cylindrical, several times as long as broad ; dissepi- ments somewhat lens-shaped ; chromatophore an axillary plate with two or more pyrenoids ; zygospores formed in the tube, sometimes occupying the whole width of one or both of the orig- inal cells, thus bounded by 2, 3, -or 4 cells ; spore with two membranes, the outer colored, smooth or sculptured ; akinetes, when occurring, with single membrane, formed by a division of the mother cell into three parts, of which the middle part be- comes the akinete. Y TO THE SPECIES OF MOUGEOTIA. i. Fertile cell bounded by 2 cells. Sect. MESOCARPICAE 2. i. Fertile cell bounded by 3 cells. Sect. PI,AGIOSPERMICAE. 14. M. tennis. i. Fertile cell bounded normally by 4 cells, exceptionally by 2 or 3. Sect. STAUROSPERMICAE. 13. 2. Conjugation scalariform. 3. 2. Conjugation lateral, rarely scalariform. 12. M. gennflexa. 2. Conjugation geniculate. 13. M. laetevirens. 3. Spore smooth. 4. 3. Spore pitted or punctate. 11. 4. Filaments 15 M diani. or less. 3. M. parvula. 4. Filaments 20 M diarn. or more. 5. 5. Spore diatn. greater than length of tube; spore extending into the cell on each side. 6. 5. Spore occupying the tube only. 9. 6. Spore 60 M diam. 5. M. minnesotensis. 6. Spore 45 M diam. or less. 7. 7. Filaments 15 n diam. or less. 7. M. delicatula. 7. Filaments 20 ^ diam. or more. 8. 8. Filaments straight. 4. M. sphaerocarpa. 8. Filaments geniculate. 6. M. divaricata. 9. Filaments about 50 M diam. 10. M. crassa. 9. Filaments 30 /j. diam. or less. 10. 10. Spores 55-60 M diam. . n. M. macrospora. 10. Spores 30-40 M diam. i. M. scalaris. ii. Spores transversely ovoid, extending into the filaments. 8. M. verrucosa. ii. Spores globose or nearly globose. 12. 12. Filaments S-io /j,, rarely 15 M diam. 2. M. nnmmuloides. 12. Filaments 25-32 /u diam. 9. M. robusta. 13. Spores punctate. 15. M. quadrangulata. 13. Spores smooth. 14. 14. Filaments bluish or purplish with age. 18. M. capucina. 14. Filaments not bluish or purplish with age. 15. THE GREEN ALGAE OF NORTH AMERICA 1 23 15. Filaments 10-12 ^ diam. 19. M. calcarea. 15. Filaments 8 /a or less. 16. 16. Spores quadrangular with concave sides. 16. M, viridis. 16. Spores quadrangular with straight sides. 17. M. elegaiitnla. 1. M. SCALARIS Hassall, 1842, p. 45; P. B.-A., No. 963 ; Mesocarpus scalaris Wolle, 1887, p. 230, PL CXL-VII, figs. 2 and 3 ; Sphaerocarpus scalaris Kiitzing, i855a, p. 2, PL V, fig. i. Filaments 25-30 fj. diam., rarely 20-23 /*> cells 2-6 diam. long, rarely more ; fertile cells somewhat elongate, slightly genicu- late ; spores 30-38 //, diam., globose or slightly ovoid, membrane yellowish brown, smooth, occupying the tube between .the two straight or very slightly bent cells.* Mass., N. J. Europe. 2. M. NUMMUI^OIDES (Hass.) De Toni, 1889, p. 713; P. B.-A., No. 714; Mesocarpus nummuloides De Bary, 1858, p. 80, PL VIII, figs. 9 and 10; Wolle, 1887, p. 231, PL CXLVIII, figs, i and 2. Filaments 8-io/x, rarely 15 /A diam., cells 5-12 diam. long; spores globose or broadly ovoid, 17-23 /x diam., rarely larger, occupying the tube but not extending into the filaments ; membrane brown, pitted. Me., Mass., N. J. Europe. 3. M. PARVULA Hassall, i843b, p. 434; Mesocarpus parvulus DeBary, 1858, p. 80, PL II, fig. 15; Wolle, 1887, p. 230, PL CXLVIII, figs. 3 & 4. Filaments 6- io/x diam., cells 5-12 diam. long; spores globose, 8-24 /u, diam., occupying the tube and sometimes projecting very slightly into the filaments ; membrane brown, smooth.! " Pools, north, south and west." Wolle. Europe. 4. M. SPHAEROCARPA Wolle, 1887, p. 227, PL CXLVI, figs, i and 2; P. B.-A., No. 1173. Filaments 20-25 /j. diam., cells 3-6 diam. long; spores spherical, about 40 p. diam., * M. reciirva (Hass.) De Toni, 1889, p. 714; Mesocarpns rccari'us Wolle, 1887, p. 231, PI. CXLVII, fig. 6, if the plate is correctly drawn, would seem to be a smaller M. scalaris, or a larger M. parvula Hass., and hardly an autonomous species. M. radicans Wolle, 1887, p. 231, PI. CXLVIII, figs. 7-10, can hardly be M. radicans Kiitz., 18553, p. i, PI. Ill, fig. i, which has rhizoidal branches smaller than the filaments, while Wolle's figures show branches as large as the filaments and of the same appearance. An examination of an authentic specimen shows the figures to be correct, although the branching is not as abundant as represented. Possibly, as suggested by Wolle, it is an abnormal condition of M. scalaris. t M. farvnla var. angusta (Hass.) Kirchner. Under this name is dis- tributed in Tilden, Auier. Algae, No. 284, a sterile plant, grown in an aquarium under abnormal conditions ; it can hardly be considered a cer- tain determination. 124 TUFTS COLLEGE STUDIES, VOL. II, No. 3 smooth, projecting from the tube into the conjugating cells.* N. J., Pa., Florida, Cal. 5. M. MINNESOTENSIS Wolle, 1887, p. 228, PI. CXL/VI, fig. 3. Filaments 15-18 /JL diarn., cells 4-5 diam. long; spores spherical, reddish brown, about 60 /j. diam., projecting much into the conjugating cells. Minn. 6. M. DIYARICATA Wolle, 1887, p. 228, PL CXL,VI, fig. 4. Filaments 20 ^ diam., cells 4-10 diam. long, fertile cells some- what geniculate ; spores about 45 //. diam., brown, projecting into the conjugating cells. Pa. 7. M. DELICATULA Wolle, 1887, p. 228, PI. CXLVI, fig. 5. Filaments 12-14 M diam., cells 4-6 diam. long; spores spherical, 25-30 p- diam., projecting slightly into the conjugating cells. Canada. The four species last named have the character in common of large spores occupying not only the whole length of the tube, but also part of each of the conjugating cells. M. sphaerocarpa has been found in California, agreeing well with Wolle's de- scription and figure ; the three others are known only by Wolle's descriptions ; if his figures are correct, it would seem difficult to place them under species before described, and they differ too much to be consolidated in one species ; there seems to be no better way than to copy the descriptions and await developments. 8. M. VERRUCOSA Wolle, 1887, p. 229, PI. CXLVIII, fig. 5. Filaments 13-14 /* diam., cells 6-10 diam. long, somewhat genic- ulate ; spores transversely ovoid, projecting into the conjugating cells, about 40X20-25 /"• ; membrane brown, coarsely granular. Alabama. An imperfectly known plant, no sterile filaments having been recorded ; but the characters seem to make it a distinct species ; unless indeed it might be an ill-preserved and inaccurately figured Debarya glyptospenna . 9. M. ROBUSTA (De Bary) Wittrock in Wittr. & Nordst., Alg. Exsicc., No. 651 ; Mcsocarpns robnstus De Bary, 1858, p. 80, PI. II, fig. 16; Wolle, 1887, p. 231, PL CXLVII, fig. 5. * M. levis (Kiitz.) Archer, 1867, Pi. VIII, figs. 1-3, is near M. sphaero- carpa, but has shorter cells and spores of about the same diameter as the filaments, but considerably longer, and set at right angles to the fila- ments. There is a somewhat doubtful report of its occurrence in the West Indies. THE GREEN ALGAE OF NORTH AMERICA 125 Filaments 25-32 /u. diam., cells 3-8 diam. long, fertile cells slightly bent; spores globose-ovoid, 40-50 /u diam., finely punc- tate, occupying the whole tube, but not projecting into the fila- ments ; membrane reddish-brown. Mass., N. J. Europe. The plant figured by Wolle has spores more nearly globose than the usual European form. 10. M. CRASSA (Wolle) De Toni, 1889, p. 716; Mesocarpus crassus Wolle, 1887, p. 230, PI. CXLVII, fig. i. Filaments about 50 fj. diam., cells 4-10 diam. long ; spores spherical, smooth, about 65 /JL diam., entirely filling the tube, but not ex- tending into the filaments. Florida. 11. M. MACROSPORA (Wolle) De Toni, 1889, p. 716; Mesa- carpus macrosporus Wolle, 1887, p. 230, PI. CXI/VII, fig. 4; P. B.-A., No. 1368. Filaments about 30 p. diam., cells 6-10 diam. long; fertile cells distinctly geniculate ; spores 55-60^ diam., occupying fully the tube, but not projecting into the fila- ments, spherical, smooth. N. H., Pa. 12. M. GENUFLEXA (Dillw.) Agardh, 1824, p. 83; P. B.-A., No. 312 ; Mesocarpiis pleurocarpus De Bary, 1858, p. Si, PI. Ill, fig. 14 ; Pleurocarpus mirabilis Wolle, 1887, p. 232, PI. CXLJX, figs. 8-15. Filaments 25-33 /j. diam., cells 2-5 diam. long, straight or geniculate, in the latter case often uniting with other filaments, but not producing fruit in this way ; spores globose or ovoid, smooth, yellowish-brown, usually formed by lateral conjugation, over the dissepiment between the two conjugating cells. N. Y., Mass., Me., N. J. Europe. A common species, forming great expansions in quiet water, pale yellowish or whitish green ; \vhen removed from the water the filaments soon tend to break up into the individual cells. Though the species is. common almost everywhere, the fruit has been considered rather rare ; but when it does occur the whole mass, no matter how extensive, is usually all in fruit at once. The scalariform conjugation is very rare, but has been observed in this country.* 13. M. LAETEVIRENS (A. Br.) Wittrock in Wittr. and Nordst., Alg., Exsicc., No. 58 ; Craterospermum laetei'ircns*Qz. Bary, 1858, p. 81, PI. Ill, figs. 1-13; Wolle, 1887, p. 235, PI. * Pleurocarpus columbianus Wolle, 1887, p. 232, PI. CXLIX, figs. 6 and 7, is described with filaments considerably larger than in M. genu- flexa ; fruit is unknown; it is probably only a form of the common species. The examination of a specimen from Bethlehem, Pa., marked Pleurocarpus coluuibianns in Wolle's writing, shows filaments from 30 to 35 fj. diam. ; but little more than in M. genuflexa. i26 TUFTS COLLEGE STUDIES, VOL. II, No. 3 CL,, figs, ii and 12; P. B.-A., No. 1367. Filaments 22-40 p. diam., cells 3-8 diam. long; conjugation geniculate ; spores short cylindrical, with the ends towards the filaments, about 40 ^ long by 45-60 ju. diam.; projecting slightly into the filaments; membrane yellow-brown, smooth. N. H., Mass. Europe. Wolle's notes on localities for this species are somewhat con- tradictory ; after "Frequent in pond near Worcester, Mass." he adds "The only specimens recognized as possibly of this genus were collected, July, 1880, in Green Pond, New Jersey." 14. M. TENUIS (Cleve) Wittrock, 1872, p. 39; Plagiosper- mum tcnue Cleve, 1868, p. 35, PI. X, figs. 6 and 7. Filaments 10-13 yudiam., cells 8-16 diam. long; one of the conjugating cells dividing into three, the lateral cells remaining sterile while the spore is formed in the central cell, the other conjugating cell being then separated from it by a wall, so that the fertile cell is bounded by three cells, two in the same and one in the other filament. Pa., Florida, N. J. Europe. Wolle describes his plant as var. minor, cells 17-18 ^ diam., and refers to Cleve's description as giving measurements 25-30 /j. diam.; evidently an error. As Wolle's plant is larger than Cleve's there is no need for preserving the varietal name. 15. M. OUADRANGULATA Hassall, i843b, p. 434 ; M. quadrata Wittr. and Nordst., Alg., Exsicc., No. 61 ; Staurospermum quadnitnm De Bary, 1858, p. 81, PI. VIII, fig. n ; Wolle, 1887, p. 234, PI. CL, figs. 6-8. Filaments 8-12 //. diam., cells 6-12 diam. long, fertile geniculate ; spores quadrangular with trun- cate or incurved angles in front view, i.e. when placed so that the two filaments are in a plane at right angles to the line of vision ; elliptic in form in side view ; occupying the width of both filaments; membrane uncolored, pitted. Mass., N. J. South Carolina. Europe. 16. M. VIRIDIS (Kiitz.) Wittrock, 1872, p. 39 ; Wittr. and Nordst., Alg. Exsicc., No. 1591 ; Staurospenmun viride De Bary, 1858. p. Si, PI. II, figs. 17 and 18; Wolle, 1887, p. 234, PI. Civ, figs. 9 and 10. Filaments 6-S ^ diam., cells 4-10 diam. long ; spores quadrangular, with concave sides ; in side view oblong ; occupying the width of both filaments, outer mem- brane colorless, smooth, depressed at the corners. Fig. ,10. N. J., Fla. Europe. 17. M. ELEGANTULA Wittrock, 1872, p. 40, PI. Ill, figs. 5-8; G. S. West, 1905, p. 284. Filaments 4-5 ^ diam., cells 15-30 diam. long; chromatophore occupying the central two thirds of the cell, with 5-8 pyrenoids ; conjugating cells genicu- THE GREEN ALGAE OP NORTH AMERICA 127 late; spore 20-24 /x long and wide, 12-14/0. thick, in face view cruciform-quadrate, in side view subelliptic with truncate apices ; outer membrane smooth, hyaline, in front view with slightly rounded angles, in side view oval. W. I. Sweden. 18. M. CAPUCINA (Bory) Agardh, 1824, p. 84; P. B.-A., Nos. 563, 1420 ; Staurospermum capucinum De Bary, 1858, p. 81 ; Wolle, 1887, p. 234, PI. CL, figs. 1-5. Filaments 15-20 /x diam., cells 6-14 diam. long, fertile cells sometimes shortened ; spores dark red to ochre color, cruciate to quadrangular with much concaved sides ; seen from the edge, linear oblong ; occupying the width of both filaments ; membrane smooth. Mass., N. J. Europe. Forming masses which except when quite young have a color ranging from bluish to deep violet. 19. M. CALCAREA (Cleve) Wittrock, 1872, p. 40, PI. II. Filaments 10-14 P- diam., cells 4-20 diam. long ; slightly genic- ulate in conjugation ; spores van-ing in form, mostly glo- bose or angular-globose, 21-50, usually 30 //, diam.; membrane brown, smooth. 'Greenland. Europe. It was in this species that the different modes of spore forma- tion, supposed to distinguish different genera, were first ob- served occurring on one individual. 2. GONATONEMA Wittrock, 1878, p. 9. Vegetative cells as in Mougeotia; conjugation unknown; aplanospore with double membrane formed in the middle of an elongated cell, the portions each side of the spore being shut off by the formation of cross walls. G. VENTRICOSUM Wittrock, 1878, p. 16, figs. 1-13; Wolle, 1887, p. 233, PI. CXIvIX, figs. 1-5; Wittf. and Nordst., Alg. Exsicc., No. 652; G. notabile, P. B.-A., No. 1174. Filaments 5-7 p. diam., somewhat bent geniculately, cells 6-16 diam. long ; spores obliquely elliptic, one side being more convex than the other; seen from the side, elliptic, 22-29 X 13-16 /A ; 12-15 p. thick, yellowish, smooth. Fig. n. Pa., Cal. Europe. Order VOLVOCALES. Vegetative cells always motile, or readily passing into a motile stage as vegetative cells, solitary or united into disk, spherical, or other shape, but not into filaments. Cells uninucleate ; chromatophore usually cup-shaped. KEY TO THE FAMILIES OF VOLVOCALES. i. Cells free, never forming colonies. i. CHLAMYDOMONADACEAE. 128 TUFTS COLLEGE STUDIES, VOL. II, No. 3 i. Cells united in colonies. 2. 2. Colonies of various form, cells motile when free, sometimes when in colonies. 3. TETRASPORACEAE. 2. Colonies spherical, ovoid, or disk-shape ; cells normally always motile. 2. VOI/VOCACEAE. Family i. CHLAMYDOMONADACEAE. Cells free, globose, ovoid, fusiform, or subcylindrical, rarely attached by gelatinous threads, with 2 or 4 cilia ; chromato- phore thick, cup-shaped, sometimes more or less split, with or without one or more pyrenoids ; asexual reproduction by zo- ospores, 2-8 formed in a vegetative cell, and similar to it in form and structure, increasing to the normal size after leaving the mother cell ; also by akinetes ; sexual reproduction by gametes, similar to the zoospores, but usually smaller, some- times 64 in a cell, in some cases with thick membrane ; in some cases the male gametes are smaller than the female ; by the copulation a spherical zygote is produced, usually red in color. When germinating it becomes green and produces asexual zoospores, in the same way as do the vegetative cells. KEY TO THE GENERA OF CHLAMYDOMONADACEAE. i. Cells fusiform. 3. CHLOROGONIUM. i. Cells spherical to ovoid. 2. 2. Protoplasmic threads passing through the cell wall. 2. HAEMATOCOCCUS. 2. No protoplasmic threads in cell wall. i. CHLAMYDOMONAS. i. CHLAMYDOMONAS Ehrenberg, 1833, p. 288. Cells globose, ovoid, or sub-cylindrical, with 2-4 cilia issuing from the same point ; cell with thin, soft, rather close coating ; chromatophore with one or more pyrenoids, and usually a red stigma ; asexual reproduction by repeated division, usually succeeded by the loss of cilia, or taking place during a Palm- ella-stage ; sexual reproduction either between similar gametes, or between male and female aplanospores. Fig. 13. Chlamydomonas forms are undoubtedly common in America, as elsewhere, but little is really known as to their identity with European species, which themselves are by no means all clearly established. De Toni, 1889, gives 6 species with some detail, and 10 "species minus notatae." Wille, 1900, notes that the genus contains about 6 species, but does not name them ; 1903, he gives 26 accepted and 23 doubtful species, of which very few coincide with species described by De Toni. Wolle, 1887, mentions as American, three species, one of them new. Miss THE GREEN ALGAE OF NORTH AMERICA 129 Snow, 1903, figures three forms found in Lake Erie and de- scribes them all as new species ; they appear to be nearly re- lated to three European species, but sufficiently distinct to give them at least a prima facie right to a place here ; one other form found in America appears identical with a described Euro- pean species; these four, with the arctic "red snow" are all that can safely be given here. As it is more than probable that these are only a small portion of the species occurring here, no key is given. 1. C. GRACILIS Snow, 1903, p. 374, PI. I, fig. I. Cells cylindrical, rarely ovoid or spherical, 10-13 /* l°ng> 5-6 p- diain.; color dull green; cilia 2, about i1/? times as long as the cell; stigma a dull red disk, about equidistant from either end ; pyre- noid at extreme posterior end. Lake Erie. Nearly related to C. angulosa Dill. 2. C. COMMUNIS Snow, 1903, p. 374, PI. I, fig. II. Cells ovoid, ellipsoid, or cylindrical, 10-13 P l°ng> 6-8 ^ diam.; color light yellowish green ; stigma inconspicuous, near anterior end ; cilia 2, slightly longer than the cell; pyrenoid near center; division longitudinal. Lake Erie. Nearly related to S. Steinii Gorosch. 3. C. GiX)BOSA Snow, 1903, p. 375, Pi. I, fig. III. Cells spherical or slightly ellipsoid, 5-8 ^ diam., cilia 2, slightly longer than the cell ; chromatophore much thickened at posterior end ; stigma small, inconspicuous ; pulsating vacuoles at anterior end ; pyrenoid at posterior end. Lake Erie. Nearly related to C. Reinhardi Dang. 4. C. MUCICOLA Schmidle, 1897, p. 17, PL II, figs. 4-8; Wille, 1903, p. 136, PL IV, fig. 6. Cells ovoid, 6-8 /x long, 3-4^ diam. ; cilia 2, longer than the cell ; pulsating vacuoles at anterior end ; no stigma ; pyrenoid near center of cell ; division transverse. Mass. Europe. 5. C. NIVAUS (Bauer) Wille, 1903, p. 147, PL III, figs. 44 and 45, PL IV, fig. 25. Cell ovoid, 26-36 ; 14-20 /A, wall thickish, uniform or thickened at the posterior end, more or less distinctly lamellate ; chromatophore cup-shaped, with one pyre- floid ; usually thoroughly colored by haematochrome ; asexual reproduction by division into aplanospores with thick, lamellate, smooth wall ; also by Palmella-stage of free, spherical, thick- walled red cells, repeatedly dividing ; sexual reproduction im- perfectly known, but resulting in a spherical or subspherical zygote, 20-34 /"• diam., with red contents and colorless wall, the 130 TUFTS COLLEGE STUDIES, VOL. II, No. 3 outer surface covered with dome-shaped prominences with hex- agonal base. Fig. 13. The "red snow' of arctic and high mountain regions; usually included in the same genus with Haematococcus pluvi- alis, often in the same species ; but Wille, 1903, seems to have determined the proper position. Greenland, Alaska. Europe. 2. HAEMATOCOCCUS Agardh, 1828, PI. XXIV. Cells similar to those of Chlamydomonas but having in the motile stages protoplasmic threads passing through the coating from the central mass to the wall ; coating usually quite thick, often different in form from the cell itself ; cell with or without red stigma, often deep red in color ; asexual reproduction by biciliate zoospores produced few in a cell ; probable sexual reproduction by smaller biciliate gametes, produced many in a cell ; but actual conjugation has not been observed. H. PLUVIALIS Flotow, 1844, p. 415, PI. XXIV, XXV; H. lacustris, P. B.-A., Xo. 114; Sphaerella lacnstris Hazen, 1899, p. 211. Resting cells spherical, 8-80 p. diam., deep red, with thick wall; dividing into 4-16 biciliate zoospores, with wide, hyaline coating, through which pass very fine, protoplasmic threads ; after a short time these spores come to rest, and divide like the parent cell ; this may continue for an indefinite number of generations ; or at any time the cells may enter into a long resting stage ; under certain circumstances the resting spore may divide into 4-32 small, narrowly cylindrical or fusiform spores, probably gametes. Fig. 14. Me. to Texas and Nebraska, Cal. Europe. Common in shallow, easily dried up pools ; forming a dull red coating on the bottom and any contained objects ; in the active state the cells are nearly or quite green, with chromato- phore covering the cell wall, and several pyrenoids. 3. CHLOROGONIUM Ehrenberg, 1837, p. 172. Cells spindle-shaped, writh two cilia at the forward end ; coat- ing very thin ; cells with two or more pyrenoids, a red stigma, and many vacuoles. Asexual reproduction by division into 4 or 8 daughter cells; sexual reproduction by zoogametes formed 1 6 or 32 in a cell, by successive division; copulation taking place between gametes of the same or different sizes, forming a round red zygospore, at whose germination 4 new individuals are produced, at first red, then green. Only one species. C. EUCHLORUM Ehrenberg, 1837, p. 172; Dangeard, iSSS, p. 114, PI. XI, figs. 5-13. Cells 25-35 M l°ng> 8 /"• diam., with thin wall and two cilia. In quiet water, aquaria, etc. Europe. THE GREEN ALGAE OF NORTH AMERICA 131 The authority for the occurrence of this species in North America is Wille, Natiirlichen Pflanzenfamilien, p. 40. Family 2. VOLVOCACEAE. Motile, biciliate vegetative cells as in Chlamydomonadaceae, but united in families of definite form, mostly spherical or ovoid, continuing motile. Asexual reproduction by the formation of daughter cells, similar to the parent ; sexual reproduction vary- ing much in the different genera, from union of similar cells, to fully specialized oogonia and antheridia. Fresh water plants. KEY TO THE GENERA OF VOLVOCACEAE. i. Cells arranged in the form of a plate with cilia on one face. i. GONIUM. i. Cells arranged in spherical, ellipsoidal, or flattened colonies; cilia not confined to one face. 3. 2. Colony ellipsoidal or spherical, cells crowded together, conical, reaching toward the center. 2. PANDQRINA. 2. Cells not crowded nor reaching towards the center of the colony. 3- 3. Colony ellipsoidal or flattened, cells uniform in size. 4. 3. Colony spherical or sphaeroidal, or if ellipsoidal, with small vege- tative and large gonidial cells. 5. 4. Colony ellipsoidal or spherical, poles not differentiated. 5. EUDORINA. 4. Colony flattened, horse-shoe-shape, poles differentiated. 4. PLATYDORINA. 5. Cells not connected by protoplasmic processes ; of two sizes, smaller vegetative at one pole and larger gonidial at the other. 3. PLEODORINA. 5. Cells connected by protoplasmic processes, not markedly different. 6. Voi/vox. i. GONIUM Miiller, 1773, p. 60. Colony in form of a quadrangular disk, with rounded angles, composed of 4-16 biciliate cells in a single layer, en- closed in a wide, colorless^ gelatinous coating, the cilia all on one side of the disk ; cells globose, or polygonal by mutual pressure ; membrane thin ; chromatophore with one large pyre- noid and red stigma. Asexual reproduction by successive division of individual cells in the colony, also by akinetes ; sex- ual reproduction not observed. KEY TO THE SPECIES OF GONIUM. i. Colony 4-celled. i- G. sociale. i. Colony i6-celled. 2. G. perforate. 132 TUFTS COLLEGE STUDIES, VOL. II, No. 3 1. G. SOCIALE (Dujard.) Warming, 1876, p. £2 ; Oltmanns, 1904, p. 150, fig. 95, 2 ; G. tetras Wittr. and Nordst., Alg. Exsicc., No. 50. Colony 4-celled, 20-48 ^ wide, vegetative cells oval, 9-20 X 5-14 A"-, often with two indentations in the outer end, cruciately arranged about a central, quadrangular, open space. N. H., Mass. Europe. 2. G. PECTORALE Miiller, 1773, p. 60; Wolle, 1887, p. 163, PI. CLI, figs. 15-18; Phyk. Univ., No. 287. Colony 25-90^ wide, composed of 16 cells, 4 central and 3 at each side; cell's 5-15 /j. diam.; akinetes spherical, 12-15 /* diam., producing 4 biciliate cells, each of which develops to the normal colony. Fig. 16. Me., Mass., Conn., N. J., Pa., N. Y., Ont., 111., Cal. Europe, Asm, Africa. In the fully developed i6-cell colony, there is a quadrangular space between the four central cells, and 16 triangular spaces among the surrounding cells ; at the four-celled stage of devel- opment this species is distinguished from G. so<.ialc by having two triangular spaces, while G. sociale has a quadrangular cen- tral opening. 2. PANDORIXA Bory, 1824, p. 600. Colony globose or subglobose, 8, 16, 32 or 64 cells forming a botryoidal mass, surrounded by a wide, gelatinous coating ; cells with close, thin membrane, red stigma, and two cilia ; chromatophore with one pyreuoid. Asexual reproduction by continued division of the cells ; sexual reproduction by the union of similar biciliate gametes, produced singly in any cell of the colony ; by the union of two such gametes, of the same or dif- ferent size, a zygote is produced, of reddish color, which after a period of rest produces 1-3 large, biciliate red zoospores ; these after a period of rest produce new colonies by vegetative divi- sion. P. MORUM (Mull.) Bory, 1824, p. 600; Ehrenberg, 1838, p. 53, PI. II, fig. 33 ; Wolle, 1887, p. 161, PI. CLIII, figs, i-io ; P. B.-A., No. 1175. Colony globose to ellipsoid, up to 220 ^ broad, usually of 16 cells, rarely more or less; cells 9-15 //. diam.; zygote with smooth external membrane. Fig. 17. Mass., Wis., 111., Cal. Europe, Asia, So. America, New Zealand. 3. PLEODORINA Shaw, 1894, p. 279. Colony spherical or ellipsoid, containing biciliate cells arranged in a single layer near the surface of the colony ; cells of two kinds, vegetative cells in the anterior part of the colony, gonidial cells in the posterior part ; cells unconnected, each with THE GREEN ALGAE OF NORTH AMERICA 133 a red stigma, one chromatophore occupying nearly the whole cell, with one to many pyrenoids ; gonidial cells developing asexually to form new colonies, by repeated divisions ; sexual reproduction unknown. A genus comprising two species, closely related to Eudorina, and until sexual reproduction has been discovered, there must be some question whether it is not a stage in the life history of the older genus. KEY TO THE SPECIES OF PI.EODORINA. i. Gonidial cells 2-3 times larger than the vegetative cells, of about the same number. i. P. californica. i. Gonidial cells somewhat larger than the four vegetative cells. 2. P. illinoisensis. 1. P. CALIFORNICA Shaw, 1894, p. 279, PI. XXVII. Col- ony up to 300 /A diarn., containing 64 or 128 cells, about equally divided between vegetative and gonidial ; gonidial cells about 2-3 times larger diameter than vegetative cells. In warm shal- low fresh water, Cal., Ind., 111. Ceylon. 2. P. ILLINOISENSIS Kofoid, 1898, p. 274, PI. XXXVI, XXXVII. Colony 46 ; 38 - - 200 ; 175 ^, containing 32, rarely 16 or 64 cells ; vegetative cells always 4 ; gonidial cells from slightly larger to twice the diam. of the vegetative cells. Fig. 1 8. In warm shallow water, 111. Germany. The ellipsoid form of this species, with the 4 vegetative cells at the forward end, distinguishes it from other species of Volvo- caceae. The colony moves forwards in the direction of the long axis, rotating at the same time about this axis ; but the rota- tion is not uniform in direction, changing frequently, like the screw of a steamer when the engine is reversed ; the movement of the colony through the water is not unlike that of the steamer's screw, except that reversing the direction of revolu- tion has no effect on the forward motion, which goes on the same, the end with the vegetative cells being always at the front. Another differentiation is that the red stigmata in the cells are brighter, as the cells are located nearer to the forward end. 4. PLATYDORINA Kofoid, 1899, p. 419. Colony much flattened, cells in one layer, but alternate!}' pointing in opposite directions ; cells differently arranged in the anterior and posterior ends ; cells all similar, biciliate, with red 134 TUFTS COLLEGE STUDIES, VOL. II, No. 3 stigma, parietal chromatophore and one pyrenoid ; asexual re- production by repeated division of all the cells, each cell thus forming a new colony ; sexual reproduction unknown. Only one species. P. CAUDATA Kofoid, 1899, p. 419, PL XXXVIII. Colony of horse-shoe-shape outline, twisted about one-eighth of a turn from right to left; maximum size 165X145X25/1; posterior end with 3 or 5 prolongations, or tails, from the common sheath ; cells 16 or 32, arranged in a marginal row of 10 or 12, and a central area of 6 or 20; oblate sphaeroidal, 15-20X15-18 ^. Figs. 19 and 20. In fresh water, 111. The alternating position of the cells, the cilia from one pro- jecting on the opposite side of the colony from the cilia of the next cell, seems to indicate an originally rounded colony, com- pressed so that the cells from opposite sides have been pushed in between each other. This, with the peculiar twist to the membrane, strongly separates this plant from all hitherto known forms. It is noteworthy that the twist of the plane is in the direction corresponding with the most frequent direction of revolution for the species. 5. EUDORINA Ehrenberg, 1832, p. 78. Colonies globose or ovoid, usually composed of 16-32-64 cells ; cells distributed nearly uniformly through the peripheral por- tion of the hyaline, gelatinous mass, globose or subglobose, with thin membrane, red stigma, and one or more pyrenoids ; externally produced into a hyaline pointed projection with two cilia, projecting from the surface of the colony. Asexual reproduction by successive division of cells, ultimately forming colonies like the parent ; sexual reproduction by oogonia and antheridia borne by separate individuals ; all the vegetative cells being transformed into antheridia, or into oogonia ; 64 fusiform or pyrifortu antherozoids, with two cilia, formed in each antheridium ; ripe oospores brownish, with smooth ex- ternal membrane, developing into new colonies. Onhy one species. E. ELEGANS Ehrenberg, 1832, p. 78, PI. II, fig. 10 ; Phyk. Univ., No. 231 ; E. stagnate Wolle, 1887, p. 160, PI. CLII, figs. 11-23. Colonies 50-200 /a diam. ; usually of 32 cells, arranged in three parallel circles of 8 each, with 4 at each pole ; cells 12-24 )"• diam. Fig. 21. In standing water, Pa., 111., Wash. Europe, So. America, New Zealand. THE GREEN ALGAE OF NORTH AMERICA 135 6. VOLVOX Linnaeus, 1758, p. 320. Colonies spherical, of from 200-20,000 cells ; cells pyriform, united by protoplasmic threads, and closely set near the surface of the sphere, the cilia projecting. A small number of cells, usually 8, are specialized as parthenogonidia, asexually form- ing new colonies by repeated division. Sexual reproduction by antheridia and oogonia ; the former containing 8-256 clavate antherozoids, with red stigma and two cilia ; oospores round, with smooth or stellate membrane ; new colonies formed by their germination, in the same wa}^ as by parthenogonidia. KEY TO THE SPECIES OF Vox, vox. i. Colonies over 500 iJ. diaru., containing several thousand cells. i. V. glohator. i. Colonies not over 300 n diam., of less than 1,000 cells. 2. V. aureus. 1. V. GLOBATOR Ljnnaeus, 1758, p. 320; Ehrenberg, 1838, p. 68, PI. IV, fig. i ; Wolle, 1887, p. 158, PI. CU, figs, i-io, GUI, figs. 1-9 ; P. B.-A, No. 1264. Colonies monoecious and usually proterandrous, 600-800 /j. diam., composed of many cells, 3,000- 20,000; vegetative cells 2-3 //, diam. ; parthenogonidia to the number of 8 formed in a colony, about 50 /u, diam. ; oogonia 20-40 in a colony, about 50 /u. diam. ; oospores brownish, outer membrane covered with stellate projections, inner membrane thick, gelatinous ; antheridia seldom over 5 in a colony, globose, 35-40 n diam., producing numerous antherozoids, 5-6 /u. long. Fig. 22. Mass., Mich., 111., Cal. Japan, Europe, One of the most striking of the fresh water algae ; the very minute cells are united into spherical colonies, large enough to be visible to the naked eye, and moving by innumerable vibra- tory cilia, two to each cell. It seems to be generally distrib- uted, and sometimes occurs in quantities in ditches and quiet pools, and is found practically throughout the year. 2. V. AUREUS Ehrenberg, 1832, p. 77; 1838, p. 71, PL IV, fig. 2; P. B.-A., No. 1176. Proterogynous ; colonies about 200 /A diam., composed of 600-900 cells; vegetative cells 4-6.5 /A diam. ; oogonia 1-15, 50-60 ^ diam., outer membrane smooth, oospore reddish-brown, 48-60 /A diam. ; antheridia numerous, 15-17 /J. diam., containing 16 closely packed antherozoids, 10-13X3-4 A<.. 111., Mich., Cal. Europe, Asia. A. smaller plant than \\ globator, and amply distinct in every particular. The three classes of reproductive organs, partheno- gonidia, oogonia, and antheridia, may occur in separate colo- 136 TUFTS COLLEGE STUDIES, VOL. II, No. 3 nies, or any two, or even all three, may occur in the same colony, but in varying proportions ; the antheridia may dis- charge the antherozoids within the mother colony, or may escape intact, and discharge their contents afterwards. The arrange- ment for cross fertilization is specially noticeable ; the oogonia in a colony ripening before the antheridia can be fertilized only by antherozoids from another colony. It is interesting to observe, here in what was a debatable land between animals and plants, as efficient arrangements for cross-fertilization as we find among flowering plants. Family 3. TETRASPORACEAE. Cells normally imbedded in gelatine, in structure like cells of Chlamydomonas, but usually without cilia ; dividing vegeta- tively ; asexual reproduction by cells assuming 2 or 4 cilia, escaping from the gelatine, and after a relatively long free existence, coming to rest, and producing a normal colony directly or after a Palmella stage ; sexual reproduction by the division of a cell into several zoogametes, by whose copula- tion is formed a zygote, germinating at once or after a resting period. KEY TO THE GENERA OF TETRASPORACEAE. i. Cells without order in formless gelatine. i. PALMEIXA. i. Cells and colony with some definite form and arrangement. 2. 2. Cells radiately arranged»in a botryoidal mass. 2. BOTRYOCOCCUS. 2. Cells not radiately arranged. 3. 3. Each family enclosed in a tough, elastic membrane. 3. INEFFIGIATA. 3. Membrane, if any, soft and delicate. 4. 4. Cells borne on filamentous, branching stalks. 5. 4. Cells without definite stalks. 6. 5. Frond soft and loose, gelatine not very conspicuous. 7. PRASINOCLADUS. 5. Frond firm, at first solid, later hollow. 8. COHINSIELLA. 6. Mature frond a hollow sac of definite form. 7. 6. Mature frond an expanded membrane or long filament. 4. TETRASPORA. 7. Sac solitary, pyriform. .5. APIOCYSTIS. 7. Sacs subcylindrical, united at base. 6. PALMODACTYLON. i. PALMELLA Lyngbye, 1819, p. 203. Cells spherical, with bell-shaped chromatophore and one pyre- noid, with broad, gelatinous, diffluent membrane; asexual re- THE GREEN ALGAE OF NORTH AMERICA 137 production by cell division in all directions, cells separating or joined in small families, forming irregular gelatinous masses ; also by akinetes and by ordinary cells developing cilia and be- coming motile ; sexual reproduction by biciliate gametes. A genus in which have been included at various times a mul- titude of forms which had no character in common but that of single cells contained in a general gelatinous mass. Many of these supposed species have been found to be stages of growth of Ulothrix, Chaetophora and other genera ; indeed a Palmella- stage is recognized in the development of a large part of the green algae. Only one species can now be considered as a dis- tinct organism in itself. P. MINIATA lyeiblein, 1830, p. 338; Wolle, 1887, p. 193, PL CLXII, fig. 10 ; Chodat, 1894, p. 587, PL XXII, figs. 1-15. Cells varying much in size, 3-40 //. diam., colored by haemato- chrome, orange-, brick-, or blood-red, or yellow, solitary or united 2-8, forming irregular gelatinous masses ; membrane thick, hyaline, more or less distinctly lamellate, diffluent ; spor- angia 10-12 /u. diam., each producing 4-8 zoospores ; or a single cell developing to a biciliate zoospore-like form ; sexual repro- duction by gametes similar to the smaller zoospores. In moist places, generally distributed. Fig. 23. Europe. Var. AEOUALIS Nageli, 1848, p. 67, PL IV. D, fig. 2 ; Wolle, 1887, p. 193, PL CLXII, fig. 10 ; P. B.-A., No. 1314. Cells of nearly uniform size, 12-15 P- diam.; color brick-red, easily changing to green ; wall thinner and less distinctly lamellate than in the type. Cal. Europe. 2. BOTRYOCOCCUS Kiitzing, 1849, p. 892. Cells ovoid-cuneate with rounded ends, radiately arranged in rounded colonies, united in botryoidal masses by a gelatinous coating, free or attached. Chromatophore covering the cell wall, without pyrenoid ; asexual reproduction by cells becom- ing biciliate and motile ; they soon come to rest, divide, and take a red color ; in these cells gametes are formed, which by conjugation form a spherical zygospore, whose further develop- is unknown. B. BRAUNII Kiitzing, 1849, p. 892 ; Wolle, 1887, p. 195, PL CXXIV, figs. 1-4; P. B.-A., Nos. 263, 1177. Family about i mm. diam., botryoidal and more or less lobed, at first green, later brownish-red ; cells ovoid or irregular, about 6 ^ diam. Floating in stagnant fresh water. Fig. 24. Mass., N. J., Cal. Europe. 138 TUFTS COLLEGE STUDIES, VOL. II, No. 3 3. INEFFIGIATA W. and G. S. West, 1897, p. 513. Cells ellipsoid or ovoid, with parietal chromatophore (and pyrenoid ?) often colored brick-red, united in spherical or sub- spherical families, the cells superficial ; each family surrounded by a tough, elastic membrane, with various irregular folds, lobes, processes and spines, the older membrane often including several generations of families ; asexual reproduction by cell division, the families separating as the}7 become too large. The cells, have considerable resemblance to those of Botryo- coccus Braitnii ; the aggregations are more complex, the outer membrane seems quite distinct from anything found in Botryo- coccus, but until we know more of the life history of the two forms, their distinctness is open to question. I. NEGLECTA W. and G. S. West, 1897, P- 5°3 >' I9°3. P- So, PL CCCCXIyVII, figs. 1-6. Cells 3-5X6-10 /x; families 20-50^ diani.; aggregations of successive families up to 350 p. In standing water. Fig. 25. Me., Mass. Europe. 4. TETRASPORA Link, 1809, p. 9. Colony (frond) gelatinous, membrauaceous ; saccate, tubular or plane ; containing globose cells in a single layer, scattered more or less in 2s and 43, the thick cell wall diffluent into the general membrane. Asexual reproduction by successive divis- ion of cells in the plane of the membrane ; also by cells becoming ciliate and motile; they later come to rest, lose their cilia, form a gelatinous membrane, and divide by 23 and 45 ; also by akin- etes. Sexual reproduction by the conjugation of small, biciliate gametes, produced 8 in a cell, the zygospore germinating at once. A genus in which quite a number of species have been de- scribed, some of them not very sharply distinguished. They are all fresh water plants, and are very common in brooks and pools. KEY TO THE SPECIES OF TETRASPORA. I. Frond cylindrical at all ages. i. T. cylindrica. i. Frond cylindrical only when young, if ever. 2. 2. Frond an irregularly inflated sac. 3. T. gelatinosa. 2. Frond at first tubular, but soon splitting into irregular segments, often much perforate. 2. T. lubrica. i. T. CYLINDRICA (Wahl.) Agardh, 1824, p. iSS; Kiitzing, 18493, PL XXX; Wolle, 1887, p. 190, PL CLXV, figs. 7 and 8 ; P. B.-A., Nos. 908, 1510. Frond attached, up to one meter long, seldom more, up to 2 cm. diarn., cylindrical, unbranched, THE GREEN ALGAE OF NORTH AMERICA 139 with stipitate base, and usually somewhat clavate tip ; consist- ency firmer than in other species of the genus; cells 14-17 /x. diarn., with thick and sharply marked wall, generally showing little of the arrangement in fours. Minn., Montana, Alaska. Europe. The type is easily recognizable by its resemblance in habit and texture to Enteromorpha intestinalis ; but the following variety is more like other species of the genus. Var. extensa (Tilclen) Collins, nov. comb. ; Tetraspora extensa. Tilden, Amer. Algae, No. 48. Fronds very long, according to the author up to 35 meters, narrow, not over i cm. wide ; or irregularly expanded with a diameter of 5 cm.; gelatinous, bright green ; cells spherical, more or less in groups of four, 10-15 )"• diam. In sluggishly flowing water, in tanks of State fish hatcheries, St. Paul, Minn. Much more gelatinous than the type, but apparently not dis- tinct ; probably a variety due to local conditions. 2. T. LUBRICA (Roth) Agardh, 1824, p. 188 ; Wolle, 1887, p. 191, PI. CIvXV, figs. 9-1 1 ;'P. B.-A., Nos. 63, 861. Frond at first attached, tubular or saccate ; soon splitting and forming irregular expansions, often with many rounded openings, some- times quite net-like ; up to 20 cm. long and wide, very gelatin- ous, usually yellowish in color; cells 7-11 p- diam., generally in fours. Fig. 26. Europe, So. America, New Zealand. Very common in spring, apparently everywhere throughout the Northern United States ; the perforated and net-like form is usually known as var. lacunosa Chauvin, but really has no characters by which it can be distinguished from the type. 3. T. GELATINOSA (Vauch.) Desvaux, 1818, p. 18 ; Wolle, 1887, p. 191 ; Phyk. Univ., No. 693 ; Ulva gelatinosa Vaucher, 1803, p. 244, PI. XVII, fig. 2. Forming inflated bullate masses, not lacunose ; very soft and gelatinous; cells 2.5-13 //. diam., very different sizes being found side by side in the same frond. Me., Mass., N. J., Iowa, Cal. Europe. Generally distributed in quiet water ; the fronds are more rounded than in other species, and the lack of uniformity in the size of the cells is marked. But there are intermediate forms between it and T. lubrica* *T. bullosa, noted in practically all manuals of fresh water algae, is now pretty well known to be a Monostroma ; it seems to be not uncommon in Europe, but no American specimens have been seen. The American specimens passing under the name of T. bullosa var. cylindracea (Hilse) 140 TKTFTS COLLEGE STUDIES, VOL. II, No. 3 Forma UNIFORMIS Collins, P. B.-A., No. 1265. Forming rounded, gelatinous masses not over 3 cm. diatn.; cells 6-8 //. diam., varying but little in size. Cal. 5. APIOCYSTIS Nageli in Kiitzing, 1849, p. 208. Colony microscopic, vesicular, attached by a stipe-like base, containing more or less numerous cells, scattered or arranged in circles, the thick wall diffluent into the general gelatinous mass of the colony ; chromatophore nearly covering the cell wall, with one pyrenoid ; cells dividing in all directions. Asexual repro- duction by cells becoming biciliate as in Tetraspora ; sexual reproduction by the union of smaller, biciliate gametes. A. BRAUNIANA Nageli, 1848, p. 67, PI. II. A, fig. i ; Wolle, 1887, p. 202, PI. CXXIII, figs. 6-10 ; Wittr. and Nordst., Alg. Exsicc., No. 356. Colony pyriform, pale green, 20-100 ^ diam., about twice as long ; containing usually 8-32, rarely up to 300 globose cells, 6-8 /u. diam. Growing on various algae in ponds and ditches.* Fig. 27. Maine, Mass., Fla. Europe, New Zealand. 6. PALMODACTYLON Nageli in Kiitzing, 1849, p. 234. Colonies microscopic, unattached, in the form of elongate sacs, simple or branched, often radiating from a common center ; con- taining globose, thick-walled cells. Asexual reproduction as in Palm dl a. P. VARIUM Nageli, 1848, p. 70, PI. II. B, fig. i ; Wolle, 1887, p. 189, PI. CXXIV, figs. 8 and 9. P. simplex Nageli, 1848, p. 70, PI. II. B, fig. 2 ; Wolle, 1887, p. 189. Colonies composed of many simple or branched, more or less radiately arranged sacs, up to 50 /u. diam. by 280 /u. long ; cells at first in 4-8 longitud- inal series, later crowded and without order, 4-7 /j. diam. Fig. 28. Maine. Europe. P. simplex appears to be merely a young or undeveloped state. "In stagnant fresh water" according to Wolle, but no definite locality given. Rabenhorst, all, as far as seen, appear to be young stages of T. lubrica or T. gelatinosa. The plants distributed as P. B.-A., No. 64, and in Til- den, Amer. Algae, No. 47, seem to correspond with T. gclafinosa fortna b. of Rabenhorst, 1868, p. 40. T. macrospora F. L. Harvey, 1892, p. 119, PI. CXXVI, figs. 1-6, should probably be included under T. gelatinosa. * A. elongata F. L. Harvey, 1892, p. 120, PL CXXVI, figs. 6-1 1, from Maine, differs from the type only in the more elongate form of the colony, and the slightly larger cells; but A. Branniana varies enough to in- clude the form and sizes given for A. elongata. THE GREEN ALGAE OF NORTH AMERICA 141 7. PRASINOCLADUS Kuckuck, 1894, p. 261. Plants filamentous, branching above ; filaments formed of compartments, those below empty, the terminal containing green cells ; cells with band-shaped chromatophore and red stigma. Reproduction by cells becoming 4-ciliate, otherwise unchanged. P. SUBSALSUS B. M. Davis in P. B.-A., No. 564; Englenop- sis subsalsa Davis, 1894, p. 388, PI. XIX. Filaments monil- iform, when mature about }{ mm. long, at first simple, then di-tri-chotomously branching ; cells oblong, 12-20X6-9 /a; chro- matophore bright green, usually extending round the cell, with no pyrenoid ; compartments of filament about the same size as the cells, separated from each other by 1-4 thin, hyaline cross- walls ; cilia at the lower end of the motile cells. Forming a thin coating, velvety or gelatinous, on pebbles, Spartina, etc. ; salt marshes and sheltered rock pools. Fig. 29. Mass., Me. Oltmanns, 1904, p. 136, proposes the family Chlorodendraceae for this and a few other forms, as being perhaps the nearest rela- tives of the Flagellates among the green algae ; but while the resemblance is striking, the line of connection with undoubted members of the Tetrasporaceae is so continuous, from Prasino- cladus subsalsns through P. lubricns Kuckuck, Ecballocystis pid- vinata Bohlin, E. japonica Yendo, and CoHinsiella tuberculata Setchell and Gardner, that the inclusion of all these forms in the Tetrasporaceae seems justified. 8. COLLINSIELLA Setchell and Gardner, 1903, p. 204. Frond gelatinous, solid or later hollow, composed of pyri- form cells, on dichotomous, gelatinous stalks tapering down- ward from the cells ; all enclosed in the general gelatine. Chromatophore band-shaped, with one large pyrenoid ; zo- ospores (?) formed from the contents of the cells. C. TUBERCULATA Setchell and Gardner, 1903, p. 204, PI. XVII, figs. 1-7; P. B.-A., No. 909; Ecballocystis Willeana Yendo, 1903, p. 199, Pi. VIII, figs. 1-15. Frond dark green, firmly gelatinous, tuberculate; cells 12-20X9-12 /u; cells divid- ing, one daughter cell remaining in position, the other pushing on, at the end of the tapering stalk ; this division many times repeated ; lower part of the frond attached to the substratum by filamentous outgrowth from the lower cells. Zoospores (?) 8-16, or sometimes more, in the cells in the middle and upper part of the frond. Forming minute tubercles on stones in pools. Fig. 30. Vancouver Isl. to Cal. 142 TUFTS CoLivEGK STUDIES, VOL. II, No. 3 The description given is made by combining the record of Setchell and Gardner with that of Yendo. The arrangement of the cells on long, dichotomous stalks, together with the firm, solid frond, seem to justify maintaining Collinsiella as a genus distinct from Ecballocystis. The transformation of vegetative into motile cells has not been observed in the genus, but is to be expected, as in other respects the genus resembles Prasino- cladus. Order PROTOCOCCALES. Vegetative cells motionless, solitary or in spherical or net-like combinations, rarely filiform. Cells uni-, rarely multi-nucleate ; chrotnatophore usually single, disk- or cup-shaped. KEY TO THE FAMILIES OF PROTOCOCCALES. i. Cells free or united in gelatinous colonies. 2. I. Cells united in regular, net- or disk-shaped colonies, not gelatinous. 5. HYDRODICTYACEAE. 2. Cells multinucleate, relatively large, irregularly branched. 2. PROTOSIPHONACEAE. 2. Cells uninucleate, of definite form. 3. 3. Cells spherical, relatively large, with many disk-shaped chromato- phores. 3- HAI.OSPHAERACEAE. 3. Cells of various forms, with single chromatophore. 4. 4. Cells dividing vegetatively. 4. SCENEDESMACEAE. 4. Vegetative cell-division rare and abnormal. i. PROTOCOCCACEAE. Family i. PROTOCOCCACEAE. Unicellular, spherical or pyriform, rarely irregular; free or attached ; asexual reproduction by zoospores or aplanospores ; sexual reproduction by zoogametes in some instances ; normal cell-division rare and exceptional. Marine or fresh water. The genus Protococcus formerly contained a heterogeneous collection of unicellular plants, which have since been all trans- ferred to widely separated genera, and the genus is now hardly recognized by any good authority. The order and family which derived their names from it still remain in good repute. P. ovalis Hansgirg in Foslie, 1890, p. 159, PI. Ill, fig. 12, was founded on a form found in tide pools near high water mark in Norway, and the same form has been found in a similar station in Maine. It has ovoid or ellipsoid cells, 8-10X9-12 /A, with thin wall and yellow-green contents, solitary or congregated in THE GREEN ALGAE OF NORTH AMERICA 143 a formless mass. Until more is known of its history, it cannot be properly located. KEY TO THE GENERA OF PROTOCOCCACEAE. i. Cells attached at base or with basal prolongation. 2. i. Cells without basal attachment or prolongation. 3. 2. Fresh water ; chromatophore cup-shaped ; one pyrenoid. 6. CHARACIUM. 2. Marine; chromatophore more or less broken ; several pyrenoids. 7. CODIOL,UM. 3. Endophytic. 4. 3. Not endophytic. 5. 4. Color more or less deep red. 4. RHODOCHYTRIUM. 4. Color green. 6. 5. Cell membrane with spines, ridges, or other projections. 2. TROCHISCIA. 5. Cell membrane smooth. i. CHI.OROCOCCUM. 6. Zoospores and gametes biciliate. 3. CHI,OROCHYTRIUM. 6. Zoospores 4-ciliate ; gametes unknown. 5. CHLOROCYSTIS. i. CHLOROCOCCUM Fries, 1825, p. 356. Cells spherical with usually thin membrane ; chromatophore covering nearly the whole cell wall, with one pyrenoid ; asexual reproduction by biciliate zoospores, produced many in a cell. The species of this genus are found in fresh water, and more especially in wet places on land, often where there are impuri- ties from sewage or other animal matter that would be fatal to most green algae. It is extremely hard to draw a line between Chlorococcum and Gloeocystis on the one hand and Zoochlorella on the other. KEY' TO THE SPECIES OF CHLOROCOCCUM. i. Endozoic. 3. C. endozoicum. i. Not endozoic. 2. 2. Forming thin coatings in moist places. i. C. huwicola. 2. Forming gelatinous submerged masses. 2. C. infusionum. 1. C. HUMICOLA (Nag.) Rabenhorst, 1868, p. 58 ; P. B.-A., No. 1066; Cystococcus humitola Niigeli, 1848, p. 85, PI. III.E. Cells varying much in size, 3-25 p. diam., spherical, solitary or united by 2-4; membrane thin, uniform, hyaline. Fig. 31. Greenland, Mass., R. I. Europe. Forming thin green coatings in moist places, especially under dripping water. 2. C. INFUSIONUM (Sclirank) Meneghini, 1846, p. 27, PI. II, fig. 3; P. B.-A., No. 1 1 19. Cells spherical, 15-45 144 TUFTS COLLEGE STUDIES, VOL. II, No. 3 rarely larger ; loosely united into light green, gelatinous masses ; wall sometimes rather thick, hyaline, more or less distinctly lamellate. Mass. Europe. Forming soft, easily scattered gelatinous masses on sub- merged objects. 3. C. ENDOZOICUM Collins, P. B.-A., No. 1323. Cells 10-25 I*, diam., spherical, thin-walled. In the mantle of the mussel, Mytilus ednlis, in tide pools. Me. C. natans Snow, 1903, p. 383, PI. Ill, fig. XI, is uncomfort- ably near C. infusionum, none of the characters given in the description being distinctive. 2. TROCHISCIA Kutzing, 1845, p. 129. Cells globose or subglobose, with several parietal chromato- phores and one or more pyrenoids, with thick membrane, having various spines, ridges, or other projections ; asexual reproduction rarely by cell division, more commonly by aplano- spores, formed many in a cell by repeated division, escaping by dissolution of the mother cell wall, with membrane at first smooth, later developing characters of the mother cell. Some of the species of Trochiscia are fresh water plankton algae, some inhabit moist places, especially dripping rocks. Care is sometimes needed to distinguish them from spores of desmids, or from unicellular stages of other algae. The knowl- edge of the American species is nearly all derived from the observations of Reinsch, 1886, and a careful comparison of his descriptions and figures is likely to leave one in a state of seri- ous doubt as to the validity of some of the species ; there are certainly three types ; respectively with warty projections, spines, and wavy ridges ; it may be that three species, one of each type, would include all our forms. KEY TO THE SPECIES OF TROCHISCIA. i. Membrane beset with papillae, spines, or wart-like prominences. 2. i. Membrane beset with wavy ridges. 5. 2. Projections warty and irregular. 3. 2. Projections spine-like. 4. 3. Projections rather distant, bluntish ; cells 18-23 p. diam. i. T. granulata. 3. Projections densely set, acutish ; cells 14-17 M diam. 2. T. aspera, 4. Spines pyramidal, of unequal length. 3. T. hirta. THE GREEN ALGAE OF NORTH AMERICA 145 4. Spines very slender, all about 5 /u, long. 4. T. aciculifera. 5. Ridges intersecting, enclosing angular areas. 5. T. reticularis. 5. Ridges parallel or concentric. 6. 6. Membrane one-sixth cell diam. 7. T. obtusa. 6. Membrane one-third cell diam. 6. T. arguta. 1. T. GRANULATA (Reinsch) Hansgirg, 1888, p. 128; P. B.-A., No. 761. Acanthococcus granulatus Reinsch, 1886, p. 239, PI. XI, figs. 3, .4, and 7. Cells solitary or united in small families, globose, 18-22 /xdiam., membrane one-fifth to one-sixth cell diam., covered with rather distant, bluntish, warty projec- tions. Mass. Europe, So. America. 2. T. ASPERA (Reinsch) Hansgirg, 1888, p. 128; Acantho- coccus asper Reiusch, 1886, p. 239, PL XI, fig. 2. Cells soli- tary, globose, 14-17 /A diam. ; membrane one-eighth to one-ninth cell diam., densely covered with somewhat acute, warty projec- tions. Dominica. Europe. 3. T. HIRTA (L/agerh.) Hansgirg, 1888, p. 128; Acantho- coccus hirtus L,agerheim, 1882, p. 78, PI. Ill, figs. 38 and 39 ; Wittr. and Nordst., Alg. Exsicc., No. 446. Cells solitary or united in small families, globose, 22-32 ^ diam., membrane one- eighth to one-ninth cell diam., with pyramidal spines of unequal length, one-fourth to one-fifth the cell diam. Fig. 32. Green- land. Europe. 4. T. ACICULIFERA (L,agerh.) Hansgirg, 1888, p. 129; Acanthococcus aciculiferus Reinsch, 1886, p. 241, PI. XI, fig. i. Cells solitary or united in small families, globose, subglobose or ovoid, 15-30 [i. diam. ; densely coated with very numerous slender spines, up to 5 /u. long. Mass. Europe. 5. T. RETICULARIS (Reinsch) Hansgirg, 1888, p. 129; P. B.-A., No. 1514; Acanthococcus reticularis Reinsch, 1886, p. 241, PL XI, figs. 12 and 14 ; including T. sporoides (Reinsch) Hans- girg, Acanthococcus sporoides Reinsch, 1886, p. 242, PL XII, fig. 24; and T. Reinschii Hansgirg, Acanthococcus sp., Reinsch, 1886, p. 242, PL XI, fig. 13. Cells solitary or united in 5-8-celled families; globose or subglobose, 15-37 p- diam., membrane one- eighth to one-ninth cell diam., with ridgy or wavy prominences, running in various directions, and intersecting to form 24-70 angular areas. Fig. 32. Mass., 111. Europe. T. sporoides, according to description and figures, differs only in not forming families, and in having 60-70 areas formed by the more numerous ridges, while T. reticularis has 24-36. T. Reinschii shows no difference whatever in the description, and 146 TUFTS COLLEGE STUDIES, VOL. II, No. 3 the figure shows only a slight difference in the form of the prominences on the ridges. 6. T. ARGUTA (Reinsch) Hansgirg, 1888, p. 129; Acantho- coccus argutus Reinsch, 1886, p. 242, PL XII, figs. 19 and 23. Cells solitary, globose, 31-43 p. diam., membrane very thick, up to y$ the total cell diam., being 12-15 V-', ridges wavy, parallel, or concentric, the projections subacute. 111. Europe. 7. T. OBTUSA (Reinsch) Hansgirg, 1888, p. 130; Acantho- coccus obtusus Reinsch, 1886, p. 243, PI. 'XII, fig. 21. Cells solitary, globose, 34-37 /* diam., membrane T6 cell diarn., with parallel or concentric wavy ridges, waves obtuse. Mass. Europe . 3. CHLOROCHYTRIUM Cohn, 1874, p. 87. Cells rounded or irregular, with parietal chromatophore and one or more pyrenoids ; asexual reproduction by akinetes, and by biciliate zoospores with red stigma, formed by repeated division, escaping singly or enclosed in a gelatinous mass ; sexual reproduction by biciliate gametes similarly formed, leav- ing the mother cell in a gelatinous mass, within which they copulate, producing a 4-ciliate zygote, which finally penetrates the tissue of the host plant, and there develops to the full size. Marine and fresh water. KEY TO THE SPECIES OF CHLOROCHYTRIUM. i. In fresh water plants. 2. i. In marine plants. 3. 2. A prolongation of the cell wall remaining where the zygote entered the host. i. C. Lemnae. 2. Cell entirely enclosed, no prologation to surface of host. 2. C. Knyanum. 3. Cells with pointed base. 3. C. Schmitzii. 3. Base of cell not pointed. 4. 4. Cell subhemispherical, base flattened. 4. C. derinatocolax. 4. Cells globose or subglobose. 5. C. inclusiim. i. C. LEMNAE Cohn, 1874, p. 87, PI. II; Klebs, 1881, p. 250, PI. Ill, figs. i-io. Endophytic in Lemna trisulca ; cells ovoid, ellipsoid or irregular, up to ioo/xdiam.; sexual reproduc- tion by biciliate .pyriform gametes, formed many in a cell, escaping by the breaking of the cell wall, enclosed in a gelat- inous vesicle, within which they conjugate ; the subspherical zygote escaping and continuing active, germinating only when falling on a frond of Lemna ; here attaching itself by the ciliate end, and pushing a tubular extension in between two epidermis cells of the host, the interior part expanding and the protoplasm passing into it, and developing to the normal form and size ; THE GREEN ALGAE OF NORTH AMERICA 147 the entering tube remaining as a cellulose thread with a knob- like expansion at the surface of the host. In autumn the cell may develop to a thick-walled akinete, producing gametes in the spring. Fig. 33. N. H. Europe. 2. C. KNYANUM Cohn and Szymanski in Kirchner, 1878, p. 102 ; Klebs, 1881, p. 255, PI. Ill, figs. 11-15 ; P. B.-A., No. 1518. Cells of varying form but usually more or less elongate, often with a distinct neck-like prolongation ; up to 100 /u, long ; zoospores formed many in a cell, escaping through an opening in the body of the cell, not in the neck-like prolongation, enclosed in gelatinous vesicle, from which they soon escape without copulation ; ovoid rather than pyriform, soon coming to rest and penetrating the host plant ; thick-walled akinetes as in C. Lemnae. Sexual reproduction unknown. In old fronds of Ceratophyllum, Elodea, Lemna minor, L. gibba, etc., but never found in L. trisnlca. Mass. Europe. As P. B.-A., No. 1517 was distributed an endophytic alga in Sphagnum from Wood's Hole, Mass,, under the name of C. Archcrianum Hieronymus, 1887, p. 296. The identification must be considered doubtful, in view of the scanty description given by the author of the species, and of some peculiarities of the Wood's Hole plant, which may make even its generic posi- tion uncertain. 3. C. SCHMITZII Rosenvinge, 1893, P- 964. fig- 56. Cells clavate or ovoid, with rounded apex and no papilla, and pointed base; up to 370 p. long by 90 /u. diam.; chromatophore occupy- ing the greater part of the cell wall, with two or more pyreuoids. Endophytic in various crustaceous marine algae, Pctrocelis, Cruoria, etc. Greenland to Me., Alaska to Washington. Northern Europe. 4. C. DERMATOCOLAX Reinke, 1889, p. 88. Cells about 30X20 /j., seen from above rounded or oval, nearly plane below ; external surface convex, subhemispherical or subconical ; asex- ual reproduction by numerous zoospores, 4-6 //. long, escaping by an opening in the end of the papilla formed at the apex of the cell at the time of fructification. In Chactopteris pliiniosa, Sphacdaria racemosa, etc. Greenland. Northern Europe. 5. C. INCLUSUM Kjellman, 1883, p. 320, PI. XXXI, figs. 8-17 ; P. B.-A., No. 514. Cell globose or subglobose, or irreg- ular by conditions of the host plant; usually 80-100 /A diam., sometimes more than twice that size ; wall at first thin, later thickening ; chromatophore covering the whole surface, with many pyrenoids ; when fruiting a cone-shaped prolongation is 148 TUFTS COLLEGE STUDIES, VOL. II, No. 3 formed, reaching to the surface of the host plant ; through this the zoospores escape. In fronds of Iridaca, Sarcophyllis, etc. Greenland, Alaska to Cal. Northern Europe. 4. RHODOCHYTRIUM Lagerheim, 1893, p. 43. Cell dark red in color, with rhizoidal branching prolongations among the cells of the host plant ; developing numerous bicili- ate gametes which escape through a narrow neck, and unite to form a zvgote which penetrates between the epidermis cells of the host, and develops a cell like the original one ; the gametes may also develop to such a cell without copulation. Thick walled resting cells also formed, whose development is unknown. The genus seems intermediate between algae and fungi ; whether it possess chlorophyll is not certain ; the mycelium-like prolongations appear to draw nourishment from the host. Only one species is known. R. SPILANTHIDIS Lagerheim, 1893, p. 43, PI. II. Cell spherical to ovoid, or irregularly rounded, 100-200 ^ diam., with relatively thin wall, communicating with the exterior of the host by a tube, the end of which opens to give passage to the gametes ; branching prolongations abundant, diminishing to about 4 /a in the final divisions ; gametes obconic to spherical with two cilia attached to the red anterior end ; resting cells 100-200 /A diam., with thick, stratified wall. In stems and leaves of Ambrosia artemisiifolia. Fig. 34. South Carolina. So. America. 5. CHLOROCYSTIS Reinhard, 1885, p. 4. Cells as in Chlorochytrium, but asexual reproduction by 4-cil- iate zoospores ; no sexual reproduction known. C. COHNII (Wright) Reinhard, 1885, p. 4, PI. I; Moore, 1900, p. 100, PI. X; P. B.-A., Nos. 565, 1121. Cells 16-26 /x diam., spherical or nearly so, chromatophore bright green, usually somewhat star-shaped and covering only part of the cell wall, but sometimes covering the whole, with one large pyre- noid ; zoospores of two sizes, one spherical, 6-7 //. diam., the other pyriform, 2.5-3.5 ^ diam., both 4-ciliate, escaping through an opening in the cell wall ; either kind of spore can germinate, and no conjugation has been observed. Fig. 35. Greenland to Mass. Europe. This species forms dense coatings on EntcroDiorpha, Schizo- ncma and other marine plants, often penetrating into the tissue of the host, but apparentlj7 never entirely covered by the latter. THE GREEN ALGAE OF NORTH AMERICA 149 6. CHARACIUM A. Braun in Kiitzing, 1849, p. 208. Cells with cup-shaped chromatophore and one pyrenoid, from narrowly lanceolate or subcylindrical to broadly ellipsoid or subglobose, often more or less bent, attached by a pointed end or by a stipe-like prolongation to the substratum ; asexual repro- duction by biciliate zoospores of two sizes, escaping by a hole or slit in the cell, also by akinetes ; the occurrence of gametes is doubtful. A genus of many species differing much in size and propor- tions of the cell, attached to larger fresh water algae or other objects ; common, but easil}' overlooked. Borzi, 1895 has re- moved a number of species, forming a new genus, Charadopsis, allied to the Confervaceae ; some of the species remaining in Charaduin are imperfectly known, and may, when more fully studied, also require removal. KEY TO THE SPECIES OF CHARACIUM. i. Growing on animals. 2. i. Not on animals. 3. 2. Ovoid or broadly ellipsoid. 8. C. De Baryanum. 2. Elongate. n. 3. Sessile. i. C. sessile. 3. With longer or shorter stipe. 4. 4. Stipe with distinct basal disk. u. C. Pringsheimii. 4. Stipe without distinct basal disk. 5. 5. Obtuse. 6. 5. Acute. 10. 6. Globose to broadly ellipsoid. 7. 6. Lanceolate to ellipsoid. 8. 7. Having a rounded stopper-like body at apex of cell. 6. C. obtusum. 7. Without such body. 5. C. heteromorphum. 8. Narrowly lanceolate to linear. 4. C. strictum. 8. Ellipsoid. 9. 9. Stipe about 4 /J- long. 3. C. Naegelii. 9. Stipe extremely short. 2.- C. Sieboldii. 10. Diarn. 15 /x or more. 9. C. acnminatitm. 10. Diam. 8 M or less. 7. C. ambiguum. ii. With slender prolonged summit. 12. C. gracilipes. ii. With blunt summit. 10. C. cyli ndri cum. i. C. SESSILE Hermann, 1863, p. 26, PI. VII, fig. 6 ; Wolle, 1887, p.§ 177, PI. CL,IX, fig. i. Cells 7-9 ^ diam., at first globose, 'later developing a small apiculum, but continuing sessile. N. J. Europe. 150 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. C. SIEBOLDII A. Braun in Kiitzing, 1849, p. 208; 1855, p. 32, PI. III. A. ; G. S. West, 1905, p. 286. Cells 15-25X4-9 n\ erect, straight, when young elongate-ellipsoid or lanceolate, rather obtuse ; when adult short ellipsoid or obovoid, obtuse ; stipe short, without basal disk. Barbados. Europe. 3. C. NAEGELII A. Braun in Nageli, 1848, p. 86, PI. III. D. ; Wolle, 1887, p. 178, PI. CUX, fig. 4; Rabenhorst, Algen, No. 512. Cells 20-42X7-18 /x, erect, straight, at first narrowly lanceolate, later oblong or ellipsoid, always obtuse; stipe slender, about 4^ long, base not swollen. Mass., Pa., Neb. Europe. 4. C. STRICTUM A. Braun, 1855, p. 37, PI. V. A. ; P. B.-A. No. 1371. Cells 23-30X6-7 fj., narrowly lanceolate or linear- oblong, straight, apex obtuse or rounded ; stipe very short, slightly swollen at the base. Mass., Cal. Europe. 5. C. HETEROMORPHUM (Reinsch) Wolle, 1887, p. 178, PI. CUX, fig. 6; Hydnanum heteromorphum Reinsch, 1875, p. 80, PI. XI, fig. 3. Cells 20X8-18 fji, globose to ellipsoid, taper- ing below into the stipe ; zoospores escaping by a wide opening at the summit ; cell after escape of the zoospores subcylindrical, about 6 fj. diam. Pa. Europe. It may be a question whether the cell continues to live after the emission of the zoospores; Reinsch's brief note does not give sufficient information. 6. C. OBTUSUM A. Braun, 1855, p. 39, PL III.E. Cell straight, 22-33 P- long, at first oblong-ellipsoid, later broadly ovoid and about half as broad as long ; with a rounded stopper- like body at the apex of the cell ; stipe very short, slightly thickened at the base. Mass. Europe. 7. C. AMBIGUUM Hermann, 1863, p. 26, PI. VII, fig. 9; Wolle, 1887, p. 177, PI. CUX, fig. 5. Cells 24-32X4-8 /x, erect, obliquely and narrowly lanceolate or ensiform, uniformly attenuate to each end, apex cuspidate, with a sometimes curved apiculum ; stipe short, slender, not swollen at the base. Mass., Pa. Europe. 8. C. De Baryanum (Reinsch) nov. comb. ; Dadylococcus De Baryanus Reinsch ,1875, p. 78, PI. XI, fig. i ; i879a, p. 38. PL I, figs. 21-24. Cells oblong to ovoid, 20-25X30-40 /*, with rela- tively stout stipe, about 15 /* long, swollen at the point of attachment into a small, thick disk. On the minute crustacean, Cyclops. Mass., Mich. Europe. Reinsch records observing the development of the mature plant just described from a motile cell about 25 p. diam., with THE GREEN ALGAE OF NORTH AMERICA 151 red stigma ; also the division of the protoplasm of an adult cell into several daughter cells ; apart from this, the development is unknown. 9. C. ACUMINATUM A. Braun in Kiitzing, 1849, p. 892 ; Hydrocytium acuminatum A. Braun, 1855, p. 26, PI. II. A. Cells 35-4OX 15-20 /x,, oblong or ovoid, apex shortly acuminate, stipe short, sometimes slightly swollen at the base. Mass. Europe. 10. C. CYUNDRICUM Lambert, 1909, p. 65, PI. 79, figs. 10-13 ; P. B.-A., No. 1269. Cell 24-430^ long, io-2o/xdiam., cylindrical with rounded apex ; tapering at the base into a short stipe, without basal disk. On the minute crustacean Branchipus vernalis. May. Mass. n. C. PRINGSHEIMII A. Braun, 1855, p. 106 ; Wolle, 1887, p. 177, PI. CLIX, fig. 3; Wittr. and Nordst., Alg. Exsicc., No. 153. Cells 20-25X6-10 /x, erect, somewhat oblique, ovoid or lance-ovoid, shortly acuminate, apiculum usually oblique ; stipe short, expanding below into a minute, yellowish disk. Mass., Pa. Europe. 12. C. GRACILIPES Lambert, 1909, p. 65, PI. 79, fig. 3-6; P. B.-A., No. 1270. Cell regularly curved, 80-480 ^ long, 7-13/1* diam., middle part fusiform, tapering above into a long seta, below into a long filiform stipe, attached to the substratum by very minute rhizoids. On Branchipus vernalis. Fig. 36. May. Mass. 7. CODIOLUM A. Braun, 1855, p. 19. Frond unicellular, ovoid to clavate or sub-cylindric, the cell wall prolonged below into a longer or shorter stipe, attached by a simple or forked expansion ; chromatophore covering the cell wall or more or less broken, with several pyrenoids ; asexual reproduction by quadriciliate zoospores, many in a cell ; also by larger aplanospores (?). The structural plan of all the species of this genus is identi- cal ; a deep green cell with thick wall, prolonged below into a slender, colorless stipe ; but the proportions and dimensions vary very much. The colored part, known as the clava, may be broadly oval, up to 120 /j. diam. ; or it may be almost cylindrical, not over 25 //, diam. The total length varies be- tween 175 and 2700 p., the shorter forms having the largest diameter of clava, and the longer forms tapering very gradually from the base to the only slightly clavate apex ; in these slender 152 TUFTS COLLEGE STUDIES, VOL. II, No. 3 forms the clava may occupy from one-tenth to three-fourths of the total length, the clava and stipe may be plainly distinct, or may pass into each other imperceptibly. The plants are mostly gregarious, often growing in abundance over long stretches of shore between tide marks, either alone or in company with other small algae ; though comparison of specimens collected at dif- ferent times and places will show many gradations of form, it is usually found that all the plants of one collecting are uniform in character. Quite a number of species have been described, but it has seemed best here to recognize only three, including others under them as forms. KEY TO THE SPECIES OF i. Growing among the tissues of other algae. i. C. Petrocelidis. i. Free. 2. 2. Clava ovoid, much thicker than the stipe. 2. C. gregarium. 2. Clava narrowly clavate, not much thicker than the stipe. 3. C. p n si 1 1 inn. 1. C. PETROCELIDIS Kuckuck, 1894, p. 259, fig. 27. Fronds endophytic, in tissue of Petrocelis ; clava ovoid or obovoid, 65-90X20-30 /u, ; stipe very slender, usually terminating below in a point. Me. to Mass. Northern Europe. The cells are developed among the vertical filaments of the host, and can be detected only by microscopic examination. The endophytic habit of this species renders the stipe unneces- sary, and it has become little more than a rudiment. 2. C. GREGARIUM A. Braun, 1855, p. 20, PL I ; Farlow, i88i,p. 58; P. B. -A., No. 165. Clava ovoid, 250-500X65- 100 /x, sharply distinguished from the stipe, which varies from 600- 1000 /* in length, and 20-30 ^ in thickness. Occurs usually in company with Calothrix, etc., on rocks and shells, along the New England coast ; rarely found unmixed, or forming so large a proportion of the mixture as to be noticeable except in micro- scopic examination. Fig. 37. Me. to N. Y. Europe. Forma intermedium (Foslie) nov. comb. ; C. intermedium Foslie, 1887, p. 193, PI. II, figs. 1-12; Wittr. and Nordst., Alg. Exsicc., No. 954. Stipe 170-250X25-40^ ; clava 150-300 >< 55- no fji. Me. Northern Europe. An extreme form, with much swollen, sometimes almost spherical clava, and short, stout stipe. It has been found among Calothrix scopidorum on islands off Portland harbor, Maine. THE GREEN AI.GAE OF NORTH AMERICA 153 3. C. PUSILUM (Lyng.) Kjellman, 1883, p. 318. Fronds long, very slender at base of the stipe, widening slowly to the clava, which is seldom over 60 /u diam. Forma TYPICUM Wittr. and Norclst., Alg. Exsicc., No. 457 ; P. B.-A., No. 1126. Widening uniformly from base of stipe to summit of clava ; stipe about twice as long as clava ; total length up to 2 mm. ; greatest diam. about 60-70 ^. The typical C. pusillum has been found in America only in Eastern Maine, where it forms velvety coatings on rocks about half-tide level, unmixed with any other alga, and forming ex- tensive patches on exposed rocks. Forma AMERICANUM Wille, in P. B.-A., No. 869. Stipe 5-10 times as long as clava, otherwise like the type. On rocks near high water mark, at Marblehead, Mass., forming a coating unmixed with other plants. Forma longipes (Foslie) nov. comb. ; C. longipes Foslie, iSSi, p. n, PI. II, fag. 4; P. B.-A., No. 26. Division be- tween stipe and clava usually marked, the lower part of clava being about double the diam. of the summit of the stipe ; stipe 30-60 p. diam., as long as clava ; total length up to 1200 //., larg- est diameter 100 fj.. This form is abundant along the coast of Maine, forming a practically unmixed coating on rocks at half tide over consid- erable stretches. In drying, the individual plants adhere in such a way as to leave the transparent stipes exposed in minute spots, giving the surface a mottled appearance, characteristic and readily recognized, but not easy to describe. Something of the same appearance is found in the other forms of these species, but not to the same extent. Family 2. PROTOSIPHONACEAE. Unicellular, terrestrial, relatively large algae, multinucleate ; chromatophore large and net-like ; cells often giving out color- less prolongations, developing into normal cells at the end ; sexual reproduction by zoogametes, asexual reproduction by zoospores. Only one genus. PROTOSIPHON Klebs, 1896, p. 221. Frond unicellular, multinucleate, with net-like chromatophore and many pyrenoids ; in form spherical, cylindrical, or irregu- lar, writh a slender, usually unbranched prolongation, penetra- ting the moist ground on which it grows ; cells dividing vege- 154 TUFTS COLLEGE STUDIES, VOL. II, No. 3 tatively, the divisions each sending down root-like prolongations. Sexual reproduction by biciliate gametes, formed several to many in a cell, and by conjugation forming a star-shaped zygote, which after a period of rest develops directly to a normal plant. Under certain conditions the gametes do not conjugate, but assume a rounded form, and soon develop to a normal plant. Asexual reproduction by aplanospores formed many in a cell, often colored red with haematochrome ; these have a longer or shoiter resting period, and either develop directly to normal plants, or produce biciliate gametes, similar to those already described. Only one species. P. BOTRYOIDES (Kiitz.) Klebs, 1896, p. 222, PI. I, figs. 1-16, P. B.-A., No. 1268 ; Botrydinm granidatnm Rostafinski and \yoronin, 1877, p. 16 in part, PI. V ; Tilden, American Algae, No. 45, in part. Exposed part ^2-5 mm. diam., vegetative di- vision usually into 4-16 cells; zoospores 15-20X5-8^; aplano- spores globose, about 40 //. diam'. On moist ground, especially clay. Fig. 38. Conn., Minn., Cal. Europe. This species seems to occur usually in connection with one or both species of Botrydinm, and was described by Rostafinski and Woronin as a condition of that genus. In Miss Tilden's specimens it is in company with B. Wallrothii Kiitz. Family 3. HALOSPHAERACEAE. Unicellular, spherical, plankton algae of relatively large size ; cell thin-walled, uninucleate, with numerous disk-shaped chro- matophores, usually with pyrenoids. Asexual reproduction by obconic zoospores, or by aplanospores. Fresh water and marine. KEY TO THE GENERA OF HALOSPHAERACEAE. i. Reproduction by numerous aplanospores. 2. EXCENTROSPHAERA. t. Reproduction by division into 2, rarely 4 cells. i. EREMOSPHAERA. i. EREMOSPHAERA De Bary, 1858, p. 56. Cells solitary, uninucleate, free, large, spherical, with num- erous small chromatophores, either parietal or radiating from the center, with 1-4 pyrenoids; cell wall normally^thin, but sometimes gelatinizing freely ; cells often showing several con- centric walls ; cells dividing into 2, rarely 4 cells, freed by the breaking up of the mother cell wall ; resting cells with thick walls and brick-red contents, ultimately resuming the normal condition. Fresh water. Only one species. E. VIRIDIS De Bary, 1858, p, 56, PI. VIII, fig. 26; Wolle, 1887, p. 200, Pl.XCLXVII, fig. ii ; P. B.-A., No. 458. Fig. 39. THE GREEN ALGAE OF NORTH AMERICA 155 Characters of the genus ; appearing under two forms : Var. MAJOR Moore, 1901, p. 311, PI. X, figs, i and 2; P. B.-A., No. 1315. Cells 70-150 /A diam. Var. MINOR Moore 1901, p. 311, PI. X, fig. 3. Cells 30-50^ diani. Greenland, Me., Mass., Conn. Europe. The unusually large size of this unicellular alga, the perfect spherical form, bright green color, and varied, often quite sym- metrical arrangement of the small chromatophores, make it an interesting object. Chodat, 1895, describes forms and modes of propagation which if confirmed would change its position among the green algae, and also identify, as stages of growth, other supposedly distinct forms. The long continued and care- ful studies by Moore failing to show anything of the kind, the present position seems the best for it. 2. EXCENTROSPHAERA Moore, 1901, p. 322. Cells uninucleate, solitary, free, large ; spherical, ellipsoidal, or sometimes irregular and angular ; chromatophores large, angular, more or less radiately arranged, covering the entire wall, each with numerous minute pyrenoids ; asexual reproduc- tion by numerous aplanospores, escaping by an opening in the cell wall, and increasing in size until the normal dimensions are reached. Fresh water. Only one species. E. VIRIDIS Moore, 1901, p. 322, PI. XII. Cells bright green, 22-55 M diam., spores 2-3 /j. diam. Fig. 40. Vt., Mass. Europe. In general appearance resembling small forms of Eremosphaera with which it often occurs; very likely the " Centrosphaera- state " of Eremosphaera described by Chodat should really be referred to this genus. Family 4. SCENEDESMACEAE. Unicellular ; cells spherical, or developing into various forms, with bell-shaped chromatophore, solitary, or united by gelatine in more or less regular colonies ; asexual reproduction by aplan- ospores. Fresh water, rarely marine plants. KEY TO THE GENERA OF SCENEDESMACEAE. I. Living in the cells of lower animals. i. ZOOCHI.ORELLA. i. Not living in the cells of animals. 2. 2. Cells contained in an extensive, gelatinous thallus. 3. 2. No external gelatinous thallus. 5. 3. Sporangia much larger than vegetative cells. 12. HORMOTILA. 156 TUFTS COLLEGE STUDIES, VOL. II, No. 3 3. Sporangia not specialized. 4. 4. Thallus a membrane or mass. 10. SCHIZOCHLAMYS. 4. Thallus a simple or branching filament. n. ELAKATOTHRIX. 5. Mature cell solitary. 6. 5. Mature cells united in colonies. 12. 6. Mother cell elongate, acicular or fusiform, dividing by oblique walls into daughter cells. 2. RHAPHIDIUM. 6. Daughter cells formed in the interior of the mother cell. 7. 7. Cells angular, often with much developed projections. 8. 7. Cells rounded. 10. 8. Cells with distinct polyedral central mass. 7. TETRAEDRON. 8. Cells of rays from a common center, without distinct central mass. 9- 9. Rays unbranched. 9. CERASTERIAS. 9. Rays di-trichotomously divided. 8. THAMNIASTRUM. 10. Cells with spines. 5. CHODATELLA. 10. Cells without spines. n. ii. Cells ovoid. 4. OOCYSTIS. ii. Cells reniform. 6. NEPHROCYTIUM. ii. Cells spherical. 3. PALMELLOCOCCUS. 12. Cells elongate, side by side in a single or double series. 13. SCENEDESMUS. 12. Cells arranged symmetrically about a center. 13. 13. Cells arranged in one plane. 14. CRUCIGENIA. 13. Cells radiating in all directions. 14. 14. Cells lunate or sickle-shaped. 19. 14. Cells not lunate or sickle-shaped ; united to the centre by gelati- nous strands or stipes. 15. 15. Stipes short, unbranched. 16. 15. Stipes branched. 17. 16. Cells with spinous projections. 18. SORASTRUM. 16. Cells without spinous projections. 17. COELASTRUM. 17. Cells in series on gelatinous strands. 21. DICTVOCYSTIS. 17. Cells at the ends of gelatinous strands. 18. 18. Cells spherical. 19. DICTYOSPHAERIUM. 18. Cells reniform, ovoid or cordate. 20. DIMORPHOCOCCUS. 19. Cells united by the convex sides. 15. SELENASTRUM. 19. Cells in no definite order in a common gelatinous envelop. 16. KlRCHNERIELLA. i. ZOOCHLORELLA Brandt, 1882, p. 140. Cells free, minute ; spherical, ellipsoid or flattened, with chro- matophore covering part of the cell wall, apparently without pyrenoid ; asexual reproduction by aplanospores formed by suc- cessive division in a cell, freed by rupture of the wall. THE GREEN ALGAE OF NORTH AMERICA 157 The two species noted below live in various lower fresh water animals ; they are so intimately associated with the hosts that they \vere long supposed to be integral parts of the same ; in many cases the alga cell divides at the same time as the host cell. Beyerinck, 1890, has proposed a genus Chlorella, includ- ing these species and some free species, which latter he thinks have been included under Chlorococcum ; it is difficult to see why Zoochlorella should be superseded, unless the ground is that it was described by a zoologist, and not by a botanist. KEY TO THE SPECIES OF ZOOCHLORELLA. i. Cells 3-6 fj. diatn. i. Z. condudrix. i. Cells 1.5-3 M diam. 2- Z. parasitica. 1. Z. CONDUCTRIX Brandt, 1882, p. 140. Endozoic ; cells 3-6 /j. diani., in tissues of Hydra and allied fresh water organ- isms. Fig. 41. Mass. Europe. 2. Z. PARASITICA Brandt, 1882, p. 140; P. B.-A., No. 1515. Endozoic; cells 1.5-3 ^ diam. ; in tissues of Spongilla, Ophry- dium and other fresh water organisms. Mass. Europe. 2. RHAPHIDIUM Kiitzing, 1845, p. 144. Cells elongate, acicular or fusiform, straight or variously curved, with pointed or rounded ends ; chromatophore nearly covering the cell wall, usually without pyrenoid ; cell dividing by oblique cross walls into 2-32 daughter cells, which separate soon after attaining their full shape and size ; less frequently remaining attached in bundles, or to the wall of the mother cell. Widely distributed fresh water plankton algae. KEY TO THE SPECIES OF RHAPHIDIUM. i. With a long seta at each. end. 4. R. setigeruin. i. Without setae. 2. 2. Cells 12-25 diam. long, ends very acute. i. R. falcatum. 2. Cells 3-12 diam. long, ends obtuse or apiculate. 3. 3. Cells variously twisted and curved. 2. R. convolittum. 3. Cells straight or nearly so, relatively stout. 3. R. Braunii. i. R. FALCATUM (Corda) Cooke, 1882, p. 19, PI. VIII, fig. 4 ; R. polymorphum Wolle 1887, p. 197; P. B.-A., No. 1179. Cells bright or yellowish green, slender, fusiform, at the middle sometimes swollen, sometimes constricted; ends very acute; straight or variously curved ; 1.5-3.5 p diam., 15-25 diam. long, up to 90 fji ; usually united 2-32 in a bundle. Greenland to Fla. and westward, Porto Rico. Europe. A common and variable species ; Micrasierias falcatus is the first name used for any of the forms now included in this species, 158 TUFTS COLLEGE STUDIES, VOL. II, No. 3 and must be considered as the type ; other forms found with us are as follows : — Var. ACICULARE (A. Br.) Hansgirg, 1886, p. 118; R. poly- morphum var. aciculare Wolle, 1887, p. 197, PI. CLX, figs. 22 and 23 ; R. aciculare Wittr., Nordst. and L,agerh., Alg. Exsicc., No. 1243. Very slender, 1.5-3 /* diam., 15-20 diam. long, acicular, straight or slightly curved, usually solitary. Mass., Pa., Neb. Europe. Var. FUSIFORME (Corda) Hansgirg, 1886, p. 119; R. fascicu- latum Nageli, 1848, p. 82, PI. IV. C, fig. i; P. B.-A., No. 1512. Fusiform, gradually tapering to each end; diam. 2-6 p., cells 12-20 diam. long, straight or more or less curved, fascicu- lately clustered. Fig. 42. Mass., Pa. Europe. 2. R. CONVOLUTUM (Corda) Rabenhorst, 1868, p. 46 ; Wolle, 1887, p. 198, PL CL,X, figs. 1-5. Cells variously curved, con- volute or contorted, 3.5-5 p- diam., 3-12 diam. long, ends obtuse or apiculate ; cells usually solitary. Me., Mass., Pa., Neb. Europe. 3. R. BRAUNII Nageli in Kiitzing, 1849, p. 891 ; Wolle, 1887, p. 198, PI. CLX, figs. 26 and 27; Wittr., Nordst. and L,agerh., Alg. Exsicc., No. 1245. Cells cyclindric-fusiform, relatively short and stout, 5-8 ^ diam., 4-6 diam. long, straight or somewhat curved, slightly tapering at both ends, subobtuse ; solitary or in pairs, rarely 3 or 4 together. Mass., Pa. Europe. 4. R. SETIGERUM (Schroder) W. and G. S. West, 1901, p. 122. Rcinschiclla f sctigera Schroder, 1897, p. 489. Cells fusi- form, the apices attenuate into long, fine setae. Diam. 3-6 /u. ; length 60-85 /A ; chromatophore with one pyrenoid. Mass. Europe. R. FRACTUM W. and G. S. West, 1899, p. 279, from Domin- ica, is described as near to R. Braunii, but somewhat narrower ; the special character given is the division of the chromatophore into four subequal parts. As the description was made from dried specimens, it is not impossible that this appearance is due to the preparation for cell division, in which case the distinction from R. Braunii would not be clear. 3. PALMELLOCOCCUS Chodat, 1894, p. 429. Cells free, globose, with wall of two or more layers, with one or more disk-shaped chromatophores without pyrenoid, often concealed by an orange-red coloring ; asexual reproduction by bipartition of the cell, also by division into numerous aplano- spores, which escape in a gelatinous vesicle. THE GREEN ALGAE OF NORTH AMERICA 159 KEY TO THE SPECIES OF PALMELLOCOCCUS. i. Chromatophores several, no coloring matter present. 3. P. therinalis. i. Chromatophore single, usually concealed by reddish coloring matter. 2. 2. Cells 3-15 M diam. ; plant of greenhouses, etc. i. P. miniatus. 2. Cells 10-40 /j. diam. ; plant of salt marshes. 2. P. marinus. 1. P. MINIATUS (Leiblein) Chodat, 1894, P- 429, PL XXV, figs. 11-26; 1902, p. 183, fig. 80; Phyk. Univ., No. 689; Pro- tococcns viridis var. miniatns Wolle, 1887, p. 181, PI. CLXII, fig. 5. Cells 3-15 fj. diam., orange red, with more or less oil ; forming a gelatinous coating on walls of greenhouses, etc. Fig. 43. Very generally distributed. 2. P. MARINUS Collins, 1907, p. 198; P. B.-A., No. 1316.* Cells 10-40 /j- diam., including wall about 2 p. thick; color from deep orange to green ; aplanospores 8-64 in a cell, spore wall quite thick while still in the mother cell ; mass of spores retaining the spherical form long after the disappearance of the mother cell wall. Among various algae in salt marsh pools. Maine. 3. P. THERMALIS G. S. West, 1904, p. 287, PI. CCCCLXIV, fig. 21. Cells 2-6 /u, diam., deep green, membrane thin and firm ; chromatophores 2 or 3, parietal disks ; aplanospores 4-16 in a cell. In hot springs. Dominica. 4. OOCYSTIS Nageli in A. Braun, 1855, p. 94. Cells ovoid ; chromatophores single or small parietal disks or grains, with or without pyrenoid ; asexual reproduction by division of the contents into 2-8 daughter cells, in the expanded membrane of the mother cell, sometimes a third generation formed before the mother cell wall breaks up. • Quite a number of species have been described in this genus, four of which have been reported in America ; it is likely that others will be found. Only numbers 3 and 4 can be considered as safely identified with the European forms of the same names. KEY TO THE SPECIES OF OOCYSTIS. i. Cells with a tubercular thickening at each end. 3. O. solitai ia. i. Cells without tubercular thickening. 2. 2. Chromatophores several in a cell. 4. O. crassa. *By mistake the combination Plenrococcits marinus was used in the description in Rhodora ; the following text indicates that Palmcllo- coccus is meant; the proper form is used in P. B.-A, No. 1316. 160 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. Chromatophore entire or halved. 3. 3. Ends rounded. i. O. Borgei. 3. Ends acute or subacute. 2. O. lacustris. 1. O. BORGEI Snow, 1903, PI. II, fig. 7. Cells ellipsoidal or slightly fusiform, ends rounded, wall uniform or slightly thick- ened at one end, with no projection, 9-13 fj. long ; chromatophore single, with pyrenoid ; cells in colonies of two or a multiple of two, free or united in a common gelatine. In plankton, Lake Krie. Sweden. 2. O. LACUSTRIS Chodat, 1897, p. 296 ; 1902, p. 190, fig. 103. Cells broadly fusiform, with membrane somewhat thick- ened at the subacute ends, chromatophore single or in distinct halves, without pyrenoid ; mother cell wall persistent, retaining the characteristic form. In plankton, Lake Erie. Europe. 3. O. SOLITARIA Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 244; P. B.-A., No. 1178. Cells generally soli- tary, occasionally 2-4 together, ellipsoid, 13-35X7-18 /*, with several chromatophores ; membrane thickish with a tubercular projection at each end. Fig. 44. Greenland, Me., Mass., Conn., Cal., West Indies. Europe, So. America. Forma MAJOR Wille, 1879, p. 26. Cells about 40X22^; often in 4-celled colonies, 60X50 /A. Alaska. Northern Europe. 4. O. CRASSA Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 355. Cells usually in twos, ellipsoid to fusiform, I4-23X 10-18 /A, with several chromatophores ; membrane thin, only slightly thickened at the ends. Me., Mass. Europe. 5. CHODATELLA Lemrnermann, 1898, p. 309. Cells ovoid or ellipsoid, the membrane bearing two to many setae not thickened at the base ; chromatophores one or many, parietal, with or without pyrenoid ; cells free or contained in the mother cell wall. Reproduction as in Ooeystis. This genus differs from Ooeystis only by the presence of the setae. Several European species have been described and may be expected here ; the following species, the only one yet reported here, is known only from Lake Erie. C. CITRIFORMIS Snow, 1903, p. 381, PI. II, fig. VIII. Cells ellipsoidal with an obtuse projection at either end, 13-23 X 8-20 //,; chromatophore single, with pyrenoid ; setae slender, in whorls about the projections at the ends of the cells. Fig. 45. Lake Erie. 6. NEPHROCYTIUM Nageli, 1848, p. 79. Cells somewhat curved, ovoid or reniform ; asexual reproduc- THE GREEN ALGAE OF NORTH AMERICA 161 tion by the division of the contents of a cell into 2-16 similar daughter cells, which remain enclosed for a longer or shorter time in the persistent mother cell wall ; chromatophore covering nearly the whole surface of the cell, with one pyrenoid. KEY TO THE SPECIES OF NEPHROCYTIUM. I. Daughter cells 2-7 fj. diam., 3-6 diarn. long. i. N. Agardhianutn. i. Daughter cells 11-22 fj. diam., 2 diam. long. 2. N. Naegelii. 1. N. AGARDHIANUM Nageli, 1848, p. 79, PI. III.C ; Wolle, 1887, p. 197, PI. CIvXIII, figs. 12-15, 17 ; Wittr. and Nordst., Alg. Exsicc., No. 528. Daughter cells 2-7 ^ diam., 3-6 diam. long ; usually 2-4-8 together, somewhat spirally arranged within the mother cell wall which may reach a length of 60 /U-. Fig. 46. Me., Mass. Europe. 2. N. NAEGELII Grunowin Rabenhorst, 1868, p. 62 ; Wolle, 18.87, P- :97- Daughter cells 11-22 /A diam., about 2 diam long; usually 16 together, irregularly arranged within the mother cell wall. Me. Europe. 7. TETRAEDRON Kiitzing, 1845, p. 129. Cells solitary, free, with parietal chromatophore occupying the whole or nearly the whole of the cell wall, with one pyre- noid ; of very various form, either polyhedric with 4-many angles, or flattened, 3-many angled, and in side view more or less elliptic ; angles from obtuse and rounded to very much pro- longed and often branched, sometimes repeatedly and finely di- vided ; asexual reproduction by aplanospores, formed 3-many in a cell, developing into the typical form of the mature plant either before or after escape from the mother cell. A genus containing species differing greatly in form, some of them very much like stages in the development of other algae ; Hydrodictyon and Pcdiastrum, for instance, produce "polyhe- dric" resting spores, and it is probable that some such forms have been described as species of Tetraedron. Whether forms here included will some time have to be removed for such reason can be decided only by future investigations. It now seems probable that some Tetraedron species, at least, are autonomous forms, not forming part of the life cycle of any other plant. Polyedrium Nageli, is a better known name for this genus than Tetraedron Kiitzing, and more appropriate ; but the latter has a priority of four years. KEY TO THE SPECIES OF TETRAEDRON. i. Cells flattened, 3 or more sided. 2. i. Cells polyhedric, but often quite irregular. 10. 162 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. Angles entire and unarmed. 3. 2. Angles spinous or forked. 6. 3. Membrane finely granulate-punctate. 5. T. pundulatum. 3. Membrane with a network of ridges. 6. T. reticulatum. 3. Membrane smooth. 4. 4. Cells triangular. 2. 7". mnticum. 4. Cells quadrangular. 5. 5. Cells 15-21 /j. diam. 3. 71. tetragoniun. 5. Cells 6-1 1 ft diam. 4. T. minimum. 6. Angles prolonged into many fine divisions. 8. T. gradle. 6. Angles mucronate or spinous only. 7. 7. Angles mucronate. i. T. tngonnm. 7. Angles spinous. 8. 8. Quadrate. 9. 8. Polygonal. 10. T. angnlositin. 9. Regularly quadrate, with short spines. 7. T. quadratum. 9. Irregularly 3- or 4-sided, with long spines. 9. T. quadricuspidatum. 10. Angles unarmed and undivided. n. 10. Angles spinous or prolonged and divided. 12. ii. Cells 17-26 p. diam. n. T. pachydermum. ii. Cells 65 /x or more in greatest diam. 13. 7". gigas. 12. Angles spinous but not lobed. 13. 12. Angles lobed or divided. 14. 13. Membrane thick, lamellate; sides plane or slightly concave ; one stout spine at each angle. 12. T. regulare. 13. Membrane thin ; sides convex, unequal ; i or 2 spines at each angle. 14. T. armatum. 14. Angles forked with rounded sinus and two sharp teeth. 15. T. bifnrcatntn. 14. Angles several times lobed or forked. 16. T. cnorme. i. T. TRIGONUM (Nag.) Hansgirg, 1888, p. 130; Polye- drinm trigonum Nageli, 1848, p. 84, PI. IV. B, fig. i ; Reinsch, 1888, p. 497, PI. IV, fig. i. Cells triangular, 12-37 /* diam.; thickness 6-16 ^ ; sides slightly sinuate, angles rounded, mucro- nate. Fig. 47. Mass., 111., Pa., Neb., Porto Rico. Europe, Asia. Reinsch gives four forms of this species, distinguished only by dimensions ; the American plant comes under forma majus Briigger, with diam. of 36 ^. Var. PUNCTATUM (Kirchner), Hansgirg, 1888, p. 130; Polye- diium trigonum var. punctatum Kirchner, 1878, p. 104; Wolle, 1887, p. 184. Membrane granulate, mucro small, papilla-like. N. j., Pa., Neb. Europe. THE GREEN ALGAE OF NORTH AMERICA 163 2. T. MUTICUM (A. Br.) Hansgirg, 1888, p. 131 ; Polyedrium muticum A. Braun, 1855, p. 94; Reinsch, 1888, p. 498, PI. IV, figs. 2, 4 and 6. Cells triangular, 13-28 p. diani., 7-10 ^ thick ; sides slightly sinuate, angles rounded, unarmed. Mass., 111., Pa. Europe, Australia. The Mass, plant comes under forma majus Reinsch ; sides slightly convex, angles rounded ; 23-28 /u, diam., 10-11 ^ thick ; the 111. plant under forma punctidatum Reinsch; sides slightly concave, membrane finely punctate, diam. 18-21 fj.. In general form and dimensions this species is much like T. trigonum, but has more rounded angles and lacks the spine or mucro characteristic of T. trigonum. 3. T. TETRAGONUM (Nag.) Hansgirg, 1889, p. 18 ; Polye- drium tetragonum Nageli, 1848, p. 84, PI. IV. B, fig. 2 ; Reinsch, 1888, p. 499, PI. IV, fig. 10 a and b ; P. trigonum var. tetrago- num Wolle, 1887, p. 184, PI. CLIX, figs. 7-10. Cells quad- rangular, sides slightly sinuate, angles rounded. Diam. 15- 21 p.. Mass., 111., Pa., Neb. Europe, Australia, So. America. Characterized by the squarish outline, with rounded angles and slightly concave sides, with no projections of any kind ; it varies slightly as to dimensions, but not otherwise. 4. T. MINIMUM (A. Br.) Hansgirg, 1888, p. 131 ; Wittr. and Nordst., Alg. Exsicc., No. 1573; Polyedrium minimum A. Braun, 1855, p. 94; Reinsch, 1888, p. 499, PI. IV, fig. 2; Wolle, 1887, p. 185, PI. CUX, figs. 28-34. Cells quadrangu- lar, 6- 1 1 i* diam., sides rather deeply emarginate, angles rounded; in side view elliptic, 3-6 //. thick. Me., Pa. Europe, Asia, So. America. Resembles a small T. tetragonum, but according to Reinsch, is not connected by intermediate forms. 5. T. PUNCTULATUM (Reinsch) Hansgirg, '1889, p. 18 ; Polyedrium punctulatum Reinsch, 1888, p. 500, PL IV, fig. 8. Cells quadrangular, 18-21X21-30 ^ ; in side view rhomboidal, 15-18 ju. at the thickest ; sides straight or slightly and irregularly repand, angles obtuse ; membrane thin, not lamellate, finely granular-punctate. Mass. Europe. Our plant is forma rectangulare Reinsch, with cells longer than wide. 6. T. RETICULATUM (Reinsch) Hansgirg, 1889, p. 18 ; Polye- dnitm reticulatum Reinsch, 1888, p. 498, PI. IV, fig. 3. Cells triangular, 26-30 /u, diam. ; with equal and nearly straight sides, 164 TUFTS COLLEGE STUDIES, VOL. II, No. 3 angles somewhat rounded ; membrane thin, covered with a net- work of very delicate ridges. Cuba. Europe, Africa. 7. T. QUADRATUM (Reinsch) Hansgirg, 1889, p. 18; Polye- drium quadratum Reinsch, 1888, p. 499, PI. IV^fig. 7. Cells regularly quadrate, sides straight or slightly convex, angles obtuse, each with a single spine ; membrane rather thick, dis- tinctly of two layers; diam. 17-34^; membrane 2-4.5 /x thick. The type occurs in Europe ; we have only forma minus acutum ; cell 17-18 p. diam.; angles subacute ; membrane only indistinctly lamellate. 111. 8. T. GRACILE (Reinsch) Hansgirg, 1889, p. 19 ; Polyedrium gracile Reinsch, 1888, p. 502, PI. VII, fig. i. Cells four-angled, sides equal, emarginate or deeply and obtusely incised, angles prolonged, three times forked, divisions divergent, ultimate divisions very slender, acute ; prolongations from the angles as long as the diam. of the cell ; cell in side view narrowly elliptic, with prolonged ends ; total diam. of cell 35-46 p. ; dis- tance between centers of sides 18-20 /J-. Mass. Var. ten ue (Reinsch) nov. comb. ; Polyedrium gracile var. tenue Reinsch, 1888, p. 502, PI. VII, fig. la. Sides very deeply in- cised, lobes of the angles in all orders very slender. Mass. 9. T. QUADRICUSPIDATUM (Reinsch) Hansgirg, 1889, p. 18 ; Polyedrium quadricuspidatiim Reinsch, 1888, p. 500, PI. VI, fig. 2. Cells 50-95X36-63 fj-, with 3 or 4 unequal sides, convex or concave, each angle ending in a long, acute, stout spine, 13-14^ long ; membrane thin, thickened at the angles ; cells in side view narrowly elliptic, with attenuate, spinous ends. Mass. Europe. Quite irregular in outline of the cell, but characterized by the four stout spines ; in Mass, is reported the type, also forma inaequale Reinsch, which seems to differ only in having spines of unequal length. 10. T. angulosum (L,arsen) nov. comb. ; Polyedriuvi angu- losum Larsen, 1904, p. 104, fig. 8. Cells more or less irregu- larly polygonal, with rounded angles, each with two short spines. Greenland. Possibly identical with Polyedrium irregulare Reinsch, 1888, p. 508, PI. VII, fig. 3. 11. T. PACHYDERMUM (Reinsch) De Toni, 1889, p. 603; Polyedrium pachydcrmum Reinsch, 1888, p. 504, PI. V, fig. 2. Cells 6-8-angled, 17-26 i*. diam., sides usually equal and sym- metrical, emarginate, angles rounded, obtuse ; in side view THE GREEN ALGAE OP NORTH AMERICA 165 elliptic ; membrane very thick, up to 5 //., of 2-many lamellae. Mass. Europe, The type is not reported with us, but only forma minus and forma leptodermum ; both forms have cells 17-19/0. diani., mem- brane thinner and less lamellate than in the type ; from Reinsch's description and figures it is not easy to find any distinction be- tween the two forms. 12. T. REGULARE Kiitzing, 1845, p. 129; Polyedrium tetrae- dricum Nageli, 1848, p. 84, PI. IV. B, fig. 3. Cells tetraedric, usually 14-50 /u, diam., sides plane or slightly concave, angles obtuse, each with a short spine ; membrane thick, distinctly lamellate. Many varieties and forms have been described ; w7e have only var. longispinum (Reinsch) De Toni, 1889, p. 605 ; Polyedrium tetraedricum var. longispinum Reinsch, 1888, p. 506, PL V, fig. la ; P. B.-A., No. 1466. Spines longer, up to half the length of a side. Mass. Europe. 13. T. GIGAS (Wittr.) Hansgirg, 1888, p. 131 ; Polyedrium gigas Wolle, 1887, p. 184, PL CL,IX, figs. 11-14; P- tumidulum var. rotundatum Reinsch, 1888, p. 506, PL VI, fig. 3a. Cells irregularly 5-6-angled, 65-75X35-45 /", sides concave, angles unarmed. Me., Mass., Pa. Europe, New Zealand. 14. T. ARMATUM (Reinsch) De Toni, 1889, p. 611; Polye- drium armatum Reinsch, 1888, p. 508, PL VI, fig. i. Cells 22-31 /u, diam., with irregular, rounded sides, and 3 or 4 incon- spicuous rounded angles, each with i or 2 stout spines, 5-8 //, long ; membrane rather thick, not lamellate. Mass. Europe. Beside the type we have var. minus Reinsch, 1888, p. 508, PL VI, fig. ic ; Cells 22 /j. diam., flattened, with 3 nearly straight sides, and 2 spines at each angle. 15. T. BIFURCATUM (Wille) L/agerheim, i893a, p. 160 ; Polyedrium trigonum var. bifurcatum Wolle, 1887, p. 184, PL CLIX, figs. 15-18. Cells tetraedric, about 30 p. diam., 3 or 4- angled, angles bifurcate, with sharp tips. Cuba, Porto Rico. So. America. 16. T. ENORME (Rail's) Hansgirg, 1888, p. 132; Polyedrium enormeWolle, 1887, p. 184, PL CLIX, figs. 19-23. Cells irreg- ularly tetraedrical, generally 25-45 /x, diam., angles prolonged, colorless, often deeply lobed, sometimes repeatedly forked : divisions mucronate. Me., Pa. Europe. With many varieties and forms, based on dimensions and on i66 TUFTS COLLEGE STUDIES, VOL. II, No. 3 the number and size of the angular projections ; all passing into each other without any sharp line. 8. THAMNIASTRUM Reinsch, 1888, p. 513. Cells solitary, free, composed of six branches issuing at right angles from a common center, di-trichotomously divided ; ulti- mate divisions acute, spreading. Only one species. T. CRUCIATUM Reinsch, 1888, p. 513, PI. VIII, fig. 3. Char- acters of the genus; ultimate divisions 100-200, 1-2 ^ diam. Fig. 49. Mass. Nothing being known as to the reproduction of the plant, wrhich has not been reported since its original discovery, its position here is provisional only, and based on habit characters. 9. CERASTERIAS Reinsch, 1867, p. 68. Cells solitary, free, consisting of elongate rays from a com- mon center, without distinct central body ; otherwise as in Tet- raedron . Doubtfully distinct from Tetraedron, differing only in the greater development of the projections and consequent reduc- tion of the main body. KEY TO THE SPECIES OF CERASTERIAS. i. Rays acute. i. C. raphidioides. i. Rays obtuse. 2. C. stanrastroides. 1. C. RAPHIDIOIDES Reinsch, 1867, p. 68, PI. V, fig. i ; 1888, p. 511. Rays 3-8, subulate, acute. Fig. 48. With many forms, of which we have two. Var. INCRASSATUM Reinsch, 1888, p. 512, PL VIII, fig. 4 f. Cell consisting of 4 or 5 rays, 2.5-3X10-15 /*, 3 or 4 arranged in a whorl at one end of the other ray ; or 2 or 3 in a whorl about one continuing the direction of the single ray, the single ray acuminate, other rays equal with rounded or sometimes acumi- nate ends. Mass. Europe, Africa. Var. INAEOUALE Reinsch, 1888, p. 512, PL VIII, fig. 4, a-c. Single ray 10-15X2-3 p., with acute 16wer end, at upper end with 3 similar acute rays, and 3 rays of about half the length, with obtuse ends. Mass. Europe, Africa. 2. C. STAURASTROIDES W. and G. S. West, 1895, p 268, PL XIV, fig. 16. Rays four, elongate, attenuate, minutely granulate, apex obtuse; thickness of central portion, 9-10 ^; total diam., 30-35 p.. On trees. Dominica. Polyedrium minutum Larsen, p. 104, fig. 7, would seem to be- long here, apparently intermediate between the two species. THE GREEN ALGAE OF NORTH AMERICA 167 10. SCHIZOCHLAMYS A. Braun in Kiitzing, 1849, p. 891. Cells spherical or ellipsoid, irregularly distributed through the colorless gelatine, free floating or attached to water plants ; chromatophore filling the cell, without pyrenoid ; cell dividing into two daughter cells, the mother cell wall remaining in 2 or 4 pieces, about the new cells. Only one species. S. GELATINOSA A. Braun in Kiitzing, 1849, p. 891 ; 1856, PI. LJI ; P. B.-A., No. 369. Forming an irregular mass, up to 10 cm. long, pale or yellowish green ; cells globose or ellipsoid, 11-14 P- wide, sometimes arranged by 2 or 4. Fig. 50. Me., Mass., Alaska, Cal. Europe. Much like a Tctraspora, but not membranaceous, and distin- guished by the persistent pieces of the mother cell wall, several generations of which may be found enclosed within the oldest. ii. ELAKATOTHRIX Wille, 1898, p. 302. Cells ovoid or fusiform, with parietal chromatophore covering all the wall except at the ends, with a large pyrenoid ; in a gen- eral gelatinous sheath ; cell dividing by a cross wall, the daugh- ter cells maintaining a longitudinal arrangement for a longer or shorter time. E. AMERICANA Wille, 1899, p. 150; P. B.-A., No. 607; Pusola viridis Snow, 1903, p. 389, PI. II, fig. VI. Cells ovoid or fusiform, 12-25X6-15 /u,, dividing across the middle, the daughter cells growing out obliquely, effacing the original lon- gitudinal order ; the gelatinous sheath in the form of a laciniate, anastomosing thallus, attached to various plants and reaching a length of several cm.; later forming floating masses of indefi- nite form. Fig. 51. Conn., L,ake Erie. 12. HORMOTILA Borzi, 1883, p. 99. Cells spherical, ovoid or ellipsoid, with one pyrenoid ; either arranged 2-4-8-16 together in a wide, more or less firm, often concentrically lamellate gelatinous mass, which may form a con- siderably extended stratum ; or distributed at intervals along colorless, branching, cylindrical, gelatinous bands. Asexual reproduction by zoospores, formed in ovoid sporangia, much larger than the vegetative cells ; zoospores 8 or more in a spor- angium, ovoid or ovoid-oblong, with red stigma, and prolonged to a point with two cilia ; escaping through a lateral opening. Only one species. H. MUCIGENA Borzi, 1883, p. 99, Pis. VIII and IX; P. B.-A., No. 1218. Cells 4-12 ju, diatn., sporangia to 3o/u,diam., zoospores 3-5X1-2.5 ^ ; mass reddish or bluish. On woodwork, etc., in standing fresh water. Fig. 52. Cal. Europe. i68 TUFTS COLLEGE STUDIES, VOL. II, No. 3 13. SCENEDESMUS Meyen, 1829, p. 774. Colonies free, of 2-8 cells, in one row, or in two rows side by side ; ovoid or with pointed ends, all smooth or all or part with spines or horns ; chromatophore nearly filling the cell, with one pyrenoid ; division either by longitudinal walls through each cell, or also by a wall through the length of a colony, dividing each cell across the middle ; daughter cells escaping either singly or united in colonies ; the free cells often differing con- siderably in form from the normal colony cells. Common in gatherings of miscellaneous algae from still water; in such collections made in warm weather one is almost certain to find colonies of Sccnedesmus ; but it is unusual to find them constituting the bulk of a collecting. KEY TO THE SPECIES OF SCENEDESMUS. i. Ends of cells obtuse or rounded. 2. i. Ends of cells acute. 2. S. obliquus. 2. Terminal cells of series with long projections. 5. S. qnadricauda. 2. All cells similar. 3. 3. Cells without teeth or spines. i. S. bijuga. 3. Cells with teeth or spines. 4. 4. Cells covered with minute spines. 4. S. Hystrix. 4. Cells with denticulate ends. 3. S. dcnticulatus. 1. S. BIJUGA (Turp.) Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 1567; P. B.-A., No. 1220; .S". obtusus Wolle, 1887, p. 173, PI. Civ VI, figs. 22-24. Colonies of 4-8 cells; cells oblong-ellipsoid or ovoid, with rounded ends, 7-18X4-7 p-, arranged in a single or double row. Greenland, Me., Mass., Neb., Cal. Europe. Var. ALTERNANS (Reinsch) Hansgirg, 1886, p. 114; P. B.-A., No. 1181. Cells broader than in the type, in two rows, alternately placed ; merely a form, hardly worthy of a name. Porto Rico, Cal. E/trope. Var. flexuosus (L,emmermann) nov. comb. ; J?. bijitgatns var. flexuosns L,emrnermann, 1898, p. 191, PI. V, fig. i ; Snow, 1903, p. 375, PI. I, fig. IV. Cells 8-16-32 in a single series, io-2o> 5-8 ju. L,ake Erie. Europe. 2. S. OBLIQUUS (Turp.) Kiitzing, 1833, p. 609; P. B.-A., No. 1320; S.acutus Nageli, 1848, PI. V. A, fig. 3. Colonies of 4-8 cells, cells fusiform with acute ends, usually in a single series, 5-27X3-9 /«.. Fig. 53. Me., Mass., Neb., Barbados, Cal. Europe. THE GREEN ALGAE OF NORTH AMERICA 169 Var. DIMORPHUS (Turp.) Hansgirg, 1886, p. 116; 6". acutus var. dimorphus Rabenhorst, 1868. p. 64; 5". dimorphus P. B.-A., Nos. 1020 and 1319. Cells united in a single series, end cells crescent-shaped, median cells straight. Me., Mass., Neb., Cal. Europe. 3. S. DENTICULATUS L,agerheim var. UNEARIS Hansgirg, 1886, p. 268. Colonies of 4-8 cells, in a nearly straight line, 4-5 ju, wide, to 15 n long ; each end with two minute teeth. Greenland, Mass., Trinidad, Washington. Europe. The tj'pe with ovoid or oblong cells, 7-8X5-11 p, occurs in Europe, but has not yet been reported from America. 4. S. HYSTRIX Lagerheim, 1882, p. 62, PI. II, fig. 18. Col- onies 2-8-celled ; cells oblong cylindric, straight with rounded ends, in a single series, 12-18X3-6^; membrane with numer- ous short spines. Porto Rico. Europe. 5. S. OUADRICAUDA (Turp.) Brebisson, 1835, p. 66 ; Ralfs, 1848, p. 190, PI. XXXI, fig. 12 ; S. caudatus Wolle, 1887, p. 172, PI. CLVI, figs, ii and 12; P. B.-A., No. 1321. Colo- nies of 2-8 cells, oblong-cylindric with rounded ends, 9-33X3-12 ju,, arranged in a single series or in two alternating rows ; end cells usually with long, filiform projections ; intermediate cells with rudimentary or no projections. Greenland, Me., N. H., Mass., Ohio, Neb., Wyo., Jamaica. Europe, Asia, New Zealand. A very common species, the description above applying to the typical form ; a number of varieties and forms have been de- scribed, of which we have probably a good part ; the four fol- lowing forms occur commonly :— Forma TYPICUS Kirchner, 1878, p. 98. Projections on ter- minal cells only. Forma SETOSUS Kirchner, 1878, p. 98. Projections on some median cells. Forma HORRIDUS Kirchner, 1878, p. 98. Projections on all cells. Forma ABUNDANS Kirchner, 1878, p. 98; Wittr. & Nordst., Alg. Exsicc., No. 525. Terminal cells with median as well as terminal projections. Var. ELiviPTicus W. &. G. S. West, iSgsa, p. 83, PI. V, fig. * Among the doubtful forms of the genus must be reckoned .S". rotunda- tits Wood, 1872, p. 91 ; S. polymorphus Wood, 1872, p. 91; 5. antennatus var. rectus Wolle, 1887. p. 172, PI. CLVI, figs. 16 and 17. i jo TUFTS COLLEGE STUDIES, VOL. II, No. 3 6; G. S. West, 1905, p. 287. Cells perfectly ellipsoid, about 12X5 p-, 4 in a single series, 2 strong spines, curved outward, on each terminal cell ; the two median cells with one such spine each, in opposite directions. Barbados. Madagascar. 14. CRUCIGENIA Morren, 1830, p. 404. Colonies free, of 4-8-16, rarely more cells, lying in the same plane, with perforations at places where the cells have divided and separated from each other ; cells with parietal chromato- phore and one pyrenoid, smooth or with prominences, touching at the middle or at the outer end, and enclosed in more or less plentiful gelatine ; asexual reproduction by the division of a cell into 4 daughter cells, arranged like the mother colony. Fresh water plankton algae. KEY TO THE SPECIES OK CRUCIGENIA. i. Cells apiculate. 3. C. apiculata. i. Cells not apiculate. 2. 2. Cells ovoid, oblong, or somewhat curved, 4-32 in a colony. i. C. rectangular is. 2. Cells rhomboidal, 4 in a colony. 2. C. crucifera. 1. C. RECTANGULARIS (A. Br.) Gay, 1891, p. ioo, PI. XV, fig. 151 ; Wittr. and Nordst., Alg. Exsicc., Nos. 53, 171. Cells 4-6X5-7 //., 4-8-16-32 in a colony, 13-55 ^ square, with rounded angles; always in groups of 4, with a quadrangular opening in the center of the group ; fragments of the mother cell wall sometimes persistent ; cells oval or oblong, touching near the outer end, or curved and touching near the middle. Fig. 54. Greenland, Mass. Europe, Asia. 2. C. crucifera (Wolle) nov. comb. ; Staurogenia cruciata Wolle, 1887, p. 171, PI. CI/VII, figs. 9-n. Cells rhomboidal, equilateral, with incurved sides and rounded angles, four form- ing a colony of the same form as the individual cell; "cells with a cruciform marking on the surface." Wolle. Pa. The figures given by Wolle are very rudimentary, but seem to indicate a distinct species. The cruciform marking of the cells is probably due to cell division in process. 3. C. APICULATA (Lemmermann) Chodat, 1902, p. 207 ; Snow, 1903, p. 376, PI. I, fig. V. Cells elongate, ovoid, or by pressure at one end subtriangular, 5-8X3-5 (*•, with an apiculum at one end, sometimes at each end ; united in fours or multiples of four in a flat, more or less regularly rectangular plate. In reproduction each cell divides to form 4 daughter cells, THE GREEN ALGAE OF NORTH AMERICA 171 which often remain attached by the general gelatinous envelop, forming a rectangular plate, which may measure as much as 150 i*. on a side, and in which the number of cells is normally some power of four. L,ake Erie. Europe. 15. SELENASTRUM Reinsch, 1867, p. 64. Cells crescent or sickle-shaped, with parietal chromatophore and no pyrenoid ; usually united in families of 4-8-16 ; asexual reproduction by division of cell into 4 daughter cells, which arrange themselves like the parent. KEY TO THE SPECIES OF SELENASTRUM. i. Cells less than 10 /u from tip to tip. i. 5. minutiiin. i. Cells 16 /j. or more from tip to tip. 2. S. Bibraianuin. 1. S. MINUTUM (Nag.) Collins, P. B.-A., No. 1422; Raph- idium minutum Nageli, 1848, p. 82, PI. IV. C, fig. 2. Cells crescent-shaped, usually uniformly curved ; 7-9 p. from tip to tip to tip, 2-3 fji wide at middle ; cells rarely continuing united, usually free. Fig. 55. Mass. Europe. 2. S. BIBRAIANUM Reinsch, 1867, p. 64, PI. IV, fig. 2 ; P. B.-A., No. 1317. Cells crescent- or sickle-shaped, uniformly curved or with tips straight ; families of four cells joined at the middle of the convex side of each cell ; these four-celled families often united in subspherical colonies of 8 or 16 cells ; cells 16-23 yu, long, 5-8 fji wide at thickest part. Me., Mass., Wash. Europe. 16. KIRCHNERIELLA Schmidle, 1893, p. 83. Cells arcuate or crescent-shaped, uninucleate, with parietal chromatophore and usually one pyrenoid, loosely aggregated without apparent order in a large gelatinous mass ; asexual re- production by division into 4 or 8 daughter cells. K. LUNARIS (Kirchner) Moebius, 1894, p. 331 ; Chodat, 1902, p. 202, figs. 121 and 122. Cells crescent-shaped, with rounded ends, 3-5 fj. diam. at middle, 6-10 ^ long. Fig. 56. Me., Mass. Europe. Var. DIANAE Bohlin, 1897, p. 20, Pi. I, figs. 28-30 ; P. B.-A., No. 1513. Cells more curved, tips acute and often not in the same plane. Me., Mass. So. America. The 'genus differs from Sclenastrum by the absence of any definite arrangement of the individual cells, and by the presence of an ample enclosing mass of gelatine. Both type and variety of K. lunaris occur among water plants in ponds, etc. 17. COELASTRUM Nageli in Kiitzing, 1849, p. 195. Cells spherical to polygonal, uninucleate, with bell-shaped 172 TUFTS COLLEGE STUDIES, VOL. II, No. 3 chromatophore and one pyrenoid ; asexual reproduction by suc- cessive division into 2-32 cells, escaping by the splitting of the mother cell wall into halves, still attached in part ; cells remain- ing separate or uniting into a colony, spherical or sub-spheri- cal, solid or hollow, joined by the gelatinous outer coating of the cell wall. Widely distributed fresh water plankton algae ; here arranged chiefly according to Senn, 1899, which is a care- ful revision of the genus. KEY TO THE SPECIES OF COELASTRUM. i. Cells united by arm-like processes from the membrane. 5. C. reticitlatiiin. i. Cells in contact or united by quite short processes. 2. 2. Cells with a short, free, external projection. 3. 2. Cells without external projection. 4. 3. Interspaces about equal to diam. of cell. 3. C. proboscidcuni. 3. Interspaces much smaller than diam. of cell. 4. C. cambricum. 4. Cells spherical or slightly elongate ; interspaces very small. i. C. microporum. 4. Cells ovoid, mutually compressed ; interspaces i-i cell diam. 2. C. sphaericuin. 1. C. MICROPORUM Nageli in A. Braun, 1855, p. 70; Senn, 1899, p. 53. PI. II, figs. 11-17 : P- B.-A., No. 1423. Cells 6-16 //. diam., spherical or slightly elongate and laterally compressed, united by the gelatinous surfaces ; interspaces much smaller than the cell diam. ; colony 40-55 p. diam. Mass., Pa., Porto Rico. Europe. 2. C. SPHAERICUM Nageli, 1848, p. 98, PI. V.C., fig. i ; Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 1241. Cells 4-20 /A diam., ovoid, mutually much flattened, deformed mostly at the outer pole ; intervals between the cells about equal to half the cell diam. ; colony 20-90 p. diam. Cuba. Europe. 3. C. PROBOSCIDEUM Bohlin, i8g7a, p. 33, PI. II, figs. 19-22 ; Senn, 1899, p. 59, PI. II, figs. 18-22; Wittr., Nordst. and lyagerh., Alg. Exsicc., No. 1240; C. microporum Wolle, 1887, p. 170, PI. ClyVI, figs. 1-3, not of Nag. Cells 7-40 p. diam., varying in form, but usually more or less angular, and with the outer pole prolonged in some form, and crowned with a gelat- inous thickening, vatying much in size and shape ; colonies usually of 2-16 cells in a loose network with relatively large open spaces. Greenland, Me., Mass., N. J. Eiiropc, So. America. C. microporum var. speciosum Wolle, 1887, p. 170, PI. fig. 4, with projections like C. proboscideum, but with cells THE GREEN ALGAE OF NORTH AMERICA 173 united by gelatinous filaments, is difficult to locate, and may possibly belong in another genus. Nothing can be determined until the plant is rediscovered. 4. C. CAMBRICUM Archer, 1868, p. 65 ; PWolle, 1887, p. 170, PL ClyVI, fig. 5. Cells 6-12 fjt- diam., angular and somewhat lobed, with a truncate projection at the middle ; interspaces quite small ; colony 20-70 /u. diam. Fig. 57. Mass. Eitrope. 5. C. RETICULATUM (Dangeard) Senn, 1899, p. 40, fig. i. Cells 2-4-8-16, 6-24 fj. diam., connected with each other by more or less numerous, arm-like prolongations of the membrane, forming a basket-like network about the spherical or spheroidal colony, which may continue intact for some time after the for- mation of daughter cells in each cell of the colony. Lake Erie. Europe. 18. SORASTRUM Kiitzing, 1845, p. 144. Colonies unattached, solid, composed of 4-32 cordate, cune- ate, reniform, or suboviform cells, which are united at the center of the colony by short stipes, and radially arranged ; cells with 1-4 spines, projecting from the larger (external) end of each cell ; chromatophore single, with one pyrenoid ; asexual repro- duction by the colony breaking up into its individual cells, which then, either at once or after division, develop each a new colony, which bursts through the membrane. Differs from Coelastrnm chiefly in the shape of the cells, and in that the colon)' breaks up before the development of the new colonies begins ; but the reproduction is not fully understood. KEY TO THE SPECIES OF SORASTRUM. i.. Outer angles of cells rounded, each with 2 spines. 1. S. spinulosuiii. i. Outer angles of cells ending each in a short, conical point. 2. S. bidtHitatiiiii. 1. S. SPINULOSUM Nageli, 1848, p. 99, PI. V.D; Wolle, 1887, p. 171, PI. ClyVI, figs. 6-10. Colony 23-60 //. diam.; cells 8-32, cuneate, outer end somewhat emarginate or subcordate, and with two pairs of spines about 15/0, long on each cell. Fig. 58. Me., Mass., Neb., Washington, Porto Rico. Europe. 2. S. BIDENTATUM Reiusch, 1867, p. 86, PI. IV, fig. i. Colony globose, about 30 /u. diam., of 8-16 cells, wedge-shaped, elliptic in surface view, with a deep sinuate incision in the outer edge, the angles slightly prolonged and somewhat acute. Porto Rico. Europe. 19. DICTYOSPHAERIUM Nageli, 1848, p. 72. Cells originally spherical, with cup-shaped chromatophore 174 TUFTS COLLEGE STUDIES, VOL. II, No. 3 and one pyrenoid ; repeatedly dividing by twos and fours, the last generation being at the apices of dichotomous, gelatinous strands, radiating from the position of the original cell, and be- ing part of the cell wall left behind in the course of the daughter cells outward ; the whole enclosed in a general gelatinous mass; asexual reproduction by the transformation of a cell into a bicil- iate zoospore, germinating immediately, or by its division into 2-4 daughter cells, giving rise to a new colony. Widely dis- tributed plankton algae. KEY TO THE SPECIES OF DICTYOSPHAERIUM. i. Cells ovoid or ellipsoid. i. D. Ehrenbergiannm. i. Cells spherical. 2. D. pulchelliun. i. Cells reniform .or cordate. 3. D. rcniformc. 1. D. EHRENBERGIANUM Nageli, 1848, p. 73, PI. II. E; Wolle, 1887, p. 186, PI. CIvVI, figs. 29-31 ; Massee, 1891, p. 457, PI. XII. Cells ovoid or ellipsoid, 6-10X4-7 M, membrane thin ; colonies ovoid or globose, of 16-64 cells, up to So /u. diani. Fig. 59. N. J. Europe. The first division of the cell is into four ; all subsequent divi- sions into two, each division in a plane at right angles to the plane of the previous division ; reproduction by biciliate zo- ospores, each formed from the contents of a cell, germinating immediately. 2. D. PULCHELLUM Wood, 1872, p. 84, PI. X, fig. 4 ; Senn, 1899, p. 74, PI. Ill, figs. 1-12; P. B.-A., No. 1511. Cells spherical, 5-9 /* diam., colonies up to 65 /A diani.; gelatinous coating ample, with distinctly radiate structure ; reproduction not observed. Me., Mass., Pa. Europe. 3. D. RENIFORME Bulnheim, 1859, p. 22, PI. II, fig. 6 ; Wolle, 1887, p. 186, PI. CLVI, fig. 28 ; Rabenhorst, Algen, No. 789. Cells reniform or subcordate, usually 10-20X6-10 /x ; colonies to 70 p. diam., somewhat irregular in form ; gelatinous coating often with ciliate projections. Me., Mass., N. J., Pa. Europe. 20. DIMORPHOCOCCUS A. Braun, 1855, p. 44. Cells on gelatinous strands radiating from the center, at the end of each strand 2-8 cells ; all cells similar, or differing in the same group ; chromatophore occupying only the middle part of the cell, \vith one pjTrenoid. Free floating plants, resembling Dictyosphaerium : the develop- ment not well understood. D. CORDATUS Wolle, 1887, p. 199, PI. CLX, figs. 30-38;- THE GREEN ALGAE OF NORTH AMERICA 175 P. B.-A., No. 159. Cells all reniforrn to cordate, the lobes turned outward, 4-8 //, diam. Fig. 60. Me., Mass., N. Y., N. J., Pa., Fla. The European D. lunatus A. Br. has cells in groups of four ; two intermediate cells ovoid, obtuse ; two lateral cells lunate ; there is no certain record of its occurrence here, but it is to be expected. 21. DICTYOCYSTIS L,agerheim, 1890, p. 5. Cells in series on gelatinous branching threads radiating from a central point ; chrotnatophore star-shaped, with one pyre- noid. D. HITCHCOCKII (Wolle) I,agerheim, 1890, p. 5 ; Dictyosphae- rium Hitchcockii Wolle, 1885, p. 126; 1887, p. 186, PI. CLVII, fig. 12. Cells 9-13X15-20 /x, ovoid, the longest dimension in the line of radiation. Fig. 61. N. J. Removed from Dictyosphaerium on account of the stellate chrornatophore, and the cells arranged along the gelatinous filaments, not merely at their ends. Family 5, HYDRODICTYACEAE. Cells multinucleate, with net-shaped chromatophore, with one or more pyrenoids ; united in families of definite form ; asexual reproduction by biciliate zoospores, uniting to form a family either in the mother cell, or in a gelatinous vesicle issuing from it ; sexual reproduction by gametes escaping from the mother cell, and by copulation forming a resting zygote, from which, by various intermediate stages, the normal vegetative form is produced. Fresh water plants. KEY TO THE GENERA OF HYDRODICTYACEAE. i. Colonies net-shape. i. HYDRODICTYON. i. Colonies disk-shape. 2. PEDIASTRUM. i. HYDRODICTYON Roth, 1800, p. 531. Colonies unattached, composed of very many cylindrical mul- tinucleate cells united at the ends by three, rarely by two or four, to form a cylindrical, wide-meshed net with closed ends ; cells all alike ; asexual reproduction by zoospores, formed in great numbers in a cell, finally arranging themselves in a mi- nute net, which is freed by the breaking up of the mother cell ; sexual reproduction by zoogametes formed in still larger num- bers in a cell, and escaping by an opening, either conjugating or developing parthenogenetically ; from the resting spore thus formed come 2-5 large zoospores, developing into irregular angular cells, " polyhedra " in which are developed many small zoospores, uniting to form a new net. Only one species. 176 TUFTS COLLEGE STUDIES, VOL. II, No. 3 H. RETICULATUM (L,.) Lagerheim, 1883, p. 71 ; Kiitziug, 1856, PI. XXXV; Wolle, 1887, p. 169, PI. CUV, figs. 11-20; P. B.-A., No. 65. Cells usually several diameters long, length up to i cm., 100-200 p. wide ; families i or 2 dm. long ; zoospores to 20,000 in a cell, gametes to 100,000. Fig. 62. Generally distributed in fresh water. Europe. A very attractive plant in appearance, the net-like frond be- ing found from microscopic size to one or two dm. in length, the cells and meshes varying correspondingly. 2. PEDIASTRUM Meyen, 1829, p. 772. Colonies unattached, disk-shaped, of round or star-shaped outline, continuous or perforate, composed of marginal cells of different shape from the interior cells ; cells multinucleate, with net-form parietal chromatophore and one pyrenoid ; asexual reproduction by biciliate zoospores, which escape from the cell enclosed in a vesicular coating, within which they arrange themselves to form a new colony ; or by the formation of a new colony in a cell, without intervention of zoospores ; sexual re- production by smaller gametes, more in a cell, copulating to form an irregular Polyedrium-like zygote, within which a new colony is formed, in the same way as in a cell of the mother colony. Species of this genus are common in fresh water plankton, and in most gatherings of miscellaneous algae from quiet water in warm weather. Their regular disks, continuous or open- work, with variously toothed or spiny marginal cells, are inter- esting objects ; but while types of the species seem clearly dis- tinct, in practice many intermediate forms will be found. A rather conservative course has been followed as regards recognizing species ; but it should be noted that Chodat, 1902, p. 224, includes as forms of P. Boryanum, the species P. forci- patum, P. vaginn and P. augulosum ; this may sometime be fully justified, but for the present it will be more convenient to retain them as species. KEY TO THE SPECIES OF PEDIASTRUM. i. Marginal cells undivided, cuspidate, i. Marginal cells bilobed. 2. 2. Lobes of marginal cells simple. 3. 2. Lobes of marginal cells etnarginate, bidentate or bind. 7. 3. Disk continuous. 4- 3. Disk perforate. 7- P- duplex. THE GREEN ALGAE OF NORTH AMERICA 177 4. Lobes of marginal cells incurved, forcipate. 3. P. forcipafian. 4. Lobes of marginal cells straight or nearly so. 5. 5. Margin finely tuberculate-crenulate. 5. P. vagnin. 5. Margin not tuberculate-crenulate. 6. 6. Lobes ending in short, broadly triangular teeth. 6. P. angulosuin. 6. Lobes ending in linear teeth. 4. P. Boryanuin. 7. Disk continuous. 8. P. tetras. 7. Disk perforate. 9. P. biradiatinn . 8. Marginal cells with a single tooth or cusp. i. P. simplex. 8. Marginal cells tridentate. 2. P. tricornutuin. 1. P. SIMPLEX Meyen, 1829, p. 772, PL XLJII, figs. 1-5 ; Wolle, 1892, p. 168, PI. IvXIV, fig. 17; Wittr. and Nordst., Alg. Exsicc., No. 524. Family of 8-16, rarely 32 cells, up to 75 /A diam.; arrangement much varied, disk continuous or per- forate ; each marginal cell ending in a single aculeate tooth or spine. Var. STURMII (Reinsch) Wolle, 1892, p. 168, PI. LXIV, fig. 1 8. Cells arranged in one or two series about a large cen- tral open space. Var. DUODENARIUM (Bailey) Rabenhorst, 1868, p. 71 ; Wolle, 1892, p. 169, PI. L/XIV, fig. 20. Disk with a central open space, surrounded by four cells, four openings in the form of arcs of circles between these cells and the 12 cells of the outer row. Mass., N. Y., Ohio, 111. Europe, So. America. These varieties are hardly worthy to be distinguished by name, being merely two of the many forms assumed by this species. None of the forms, however, need be mistaken for any other species, as there is no other species in which each cell ends in a long, aculeate projection. 2. P. TRICORNUTUM Borge, 1892, p. 4, fig. 3. Disk contin- uous, rounded, 32-40^ diam.; marginal cells 10-18X9-10 /a, tra- peziform, with three teeth on the margin ; disk cells polygonal. Greenland. Northern Europe. 3. P. FORCIPATUM (Corda) A. Braun, 1855, P- 86 > Wolle, 1892, p. 169, PI. L/XIV, figs. 21, 30-31. Cells 8-16, rarely more, forming a continuous disk ; disk cells about 24 //, wide, polygonal or slightly incurved on the outer side ; marginal cells deeply incised, bilobed, lobes incurved, acuminate. Mass., N. J., Pa. Europe. The small disks, and especially the forcipate prolongations of the marginal cells, seem sufficiently characteristic. 4. P. BORYANUM (Turp.) Meneghini, 1840, p. 210; Nageli, 1848, p. 95, PI. V.B, fig. i ; Wolle, 1892, p. 169, PL L.XIV, 178 TUFTS COLLEGE STUDIES, VOL. II, No. 3 figs. 29-32; P. B.-A., No. 1180. Cells 4-64, rarely 128, 10-20 ^ wide, forming a continuous, circular or elliptical disk ; disk cells 4-6-angled, the external side varying from prominent to repand ; marginal cells more or less emarginate or bilobed, each lobe ending in a longer or shorter terete, obtuse to capitellate projection. Fig. 63. Greenland, Me., Mass., N. J., Pa., Ohio, 111., Neb., Cal., Alaska. Europe, Asia, So. America. A very common and widely distributed species, with many varieties ; to be recognized more by the general combination of characters than by any one detail, though the two terete pro- longations from each marginal cell are usually sufficiently characteristic. Var. UNDULATUM Wille, 1879, p. 28 ; P. nndnlatum (Wille) Boldt, 1893, p. 157, fig. i. Cells sometimes 256 ; larger than in the type ; disk cells with irregularly undulate margin ; marginal cells distinctly bilobed. Greenland. Europe. Var. GRANULATUM (Kiitz.) A. Braun, 1855, p. 90 ; P. B.-A., No. 1324 ; with smaller cells and families, and verrucose mem- brane. Greenland, Nebraska and California. 5. P. VAGUM Kiitzing, 1845, p. 143; A. Braun, 1855, p. 82, PL VI, figs. 27-28 ; P. B.-A., No. 1519. Cells 32-128 in a disk, disk continuous, of varying form, up to 250 ^ wide, cells in disk to 30 /j. wide, 5-6-angular ; marginal cells about 10 p. wide, with two short, obtusely triangular projections ; margin and membrane generally finely tubercular-crenulate. Greenland, Me., Mass. Eiirope, So. America. The large disk of irregular form, composed of many cells, with the crenulate margin, makes this quite a distinct species. 6. P. ANGULOSUM (Ehrenb.) Meneghini, 1840, p. 211 ; A. Braun, 1855, p. 84, PI. VI, fig. 26 ; Wolle, 1892, p. 169, PL LXIV, fig. 28. Cells 16-64, UP to 19 /A diam., 5-6-angular, forming a continuous disk, up to 120 /x diam. ; marginal cells with truncate base, wider above, with a more or less deep sinus, the inner side of the ray prolonged in a slightly incurved tooth, the outer edge with a slight apiculum. Me., N. J., Ohio, Neb., Alaska. Europe, Asia. Each marginal cell has a projection on each side of the cen- tral rounded sinus ; the inner edge of this terminates in a sub- linear tooth, not exactly on the radial line, but parallel to the tooth on the other side, of the sinus ; the outer edge of the pro- jection has merely a small apiculum, as if produced by the pressure of the adjacent cell. THE GREEN ALGAE OF NORTH AMERICA 179 7. P. DUPLEX Meyeu, 1829, p. 772, PI. XLIII, figs. 6-20; P. pertusum Wolle, 1892, PI. LXIV, figs. 33, 34; Wittr. and Nordst., Alg. Exsicc., No. 1237. Cells 8-32, 6-28 /a wide, form- ing a disk perforate with many rounded openings of varying size ; disk cells quadrangular, or emarginate on one or more sides ; marginal cells joined only at the base, deeply bilobed, lobes straight, each ending in an acute or obtuse, not capitellate prolongation. Mass., Me., N. J., 111., Neb. Europe. A common species, and with many varieties; but fairly well recognized by the numerous rounded openings. Var. CLATHRATUM A. Braun, 1855, p. 93 ; Wittr. and Nordst., Alg. Exsicc., No. 1562. Disk cells deeply emarginate, making the openings proportionally larger than in the type. Mass., Neb. Eitrope. Var. BRACHYLOBUM A. Braun, 1855, p. 93, PI. VI, fig. 25 ; Wolle, 1892, PI. IvXIV, fig. 35. Disk and marginal cells only slightly emarginate ; openings and marginal projections incon- spicuous. Me. Europe. 8. P. TETRAS (Ehrenb.) Ralfs, 1844, p. 469, PI. XII, fig. 4 ; P. Ehrenbergii A. Braun, 1855, p. 97, PI. V.H. ; Wolle, 1892, p. 170, PI. LXIV, figs. 25-27. Cells 4-16, 9-20 /A wide, disk cells polygonal, one side repand or with a very deep and narrow incision ; marginal cells very deeply incised, lobes emarginate, bidentate or bifid. Me., Mass., N. J., Ohio, 111., Neb., Colo., Porto Rico, Mexico. Europe, Asia, So. America. The small continuous disk, with deep linear incisions in nearly every cell, and with cell lobes divided, easily identifies this species. 9. P. BIRADIATUM Meyen, 1829, p. 773, PI. XUII, figs. 21-22; P. rotnla A. Braun, 1855, p. 101, PI. VI, figs. 1-3. Cells 8-32, 9-21 /u. wide ; disk cells deeply incised, leaving rather large openings ; marginal cells attached at the base only, in- cised to or below the middle, each division ending in two acute or obtuse denticulations. Greenland. Europe. From P. duplex, which has a similarly perforate frond, this can be distinguished by the double division of the marginal cells, giving two projections to each lobe. Var. EMARGINATUM (A. Braun) L,agerheim, 1882, p. 54; P. rotula var. cmarginatum A. Braun, 1855, p. 102, PI. VI, figs. 4, 8, 9, n. Disk cells slightly sinuate-emarginate ; marginal cells less deeply incised, divisions emarginate, bidentate or sub- truncate. Greenland. Europe. i8o TUFTS COLLEGE STUDIES, VOL. II, No. 3 Order ULOTRICHALES Simple or branched filaments, sometimes membranes, rarely in few-celled families ; cells uninucleate, chromatophore usually single, band-, disk-, net-, or star-shape, generally with one or more pyrenoids. Marine and fresh water. KEY TO THE FAMILIES OF ULOTRICHALES. i. Chromatophore star-shaped ; zoospores unknown. 3. PRASIOLACEAE. i. Chromatophore net-, disk- or band-shaped. 2. 2. Cells usually red or brown by haematochrome ; frond filamentous, branching. 9. CHROOLEPIDACEAE. 2. Vegetative cells true green. 3. 3. Fronds unbranched filaments. 4. 3. Fronds branched or membranaceous, rarely in few-celled families. 6. 4. Sexual reproduction by isogamous gametes, i. ULOTRICHAS^S. 4. Sexual reproduction by oogonia and antheridia. 5. 5. Chromatophore net-shaped. 5. OEDOGONIACEAE. 5. Chromatophore disk- or band-shaped. 4. CYLINDROCAPSACEAE. 6. Frond membranaceous, either flat or forming a tube. 2. ULVACEAE. 6. Frond filamentous, branching, or a few-celled family ; usually with hairs. 7. 7. Sexual reproduction by isogamous zoogametes. 6. CHAETOPHORACEAE. 7. Sexual reproduction by oogonia and antheridia. 8. 8. Vegetative filaments prostrate. 9. 8. Vegetative filaments erect. 5. OEDOGONIACEAE. 9. Oospore with cellular envelope; vegetative filaments radiate or united to a disk. 8. COLEOCHAETACEAE. 9. Oospore without cellular envelope; vegetative filaments irregularly spreading. 7. HERPOSTEIRACEAE. Family i. ULOTRICHACEAE. Frond a normally unbranched, uniseriate filament, rarely partly multiseriate, of uniuucleate cells, each of which, with the exception of the basal cell, when present, is capable of produc- ing spores or gametes. Chromatophore either a single, complete or broken band, or a network, or one to several disks ; usually with one or more pyrenoids. Asexual reproduction by bi- or 4- ciliate zoospores, by akinetes, or by aplanospores ; sexual repro- duction by the conjugation of biciliate zoogametes. THE GREEN ALGAE OF NORTH AMERICA 181 A family of fresh water and marine algae, fairly well marked off from other forms by the characters just given ; but it is by no means easy to determine by hasty inspection whether a plant belongs to this family or to the Cladophoraceae . In external ap- pearance and even by ordinary microscopic inspection, there is no test to distinguish Ulothrix, Hormiscia, or Chaeto mo rpha ; only by actual acquaintance with the individual species can one acquire any certainty of determination. In the arrangement of this family Hazen, 1902, has been fol- lowed, except that Conferva has been removed. While there may be some doubt as to the distinctness of all the species he h«s accepted, and he himself expresses some such doubt, his work represents the only careful and continued study that has been made of the living plants in this country, and may well be accepted until modified by later investigations. KEY TO THE GENERA OF ULOTRICHACEAE. i. Filaments uionosiphonous below, parenchymatous above. 4. SCHIZOMERIS. i. Filaments monosiphonous throughout. 2. 2. Cells loosely attached, in a wide, gelatinous sheath. 3. RADIOFIUJM. 2. Cells forming a cylindrical or moniliform filament, without ex- ternal gelatinous sheath. 3. 3. Without pyrenoid. 6. MICROSPORA. 3. With one or more pyrenoids. 4. 4. Chromatophore a parietal disk or plate. 5. STICHOCOCCUS. 4. Chromatophore a zonate band, sometimes incomplete. 5. 5. Apical and basal cells attenuate. 2. URONEMA. 5. Apical and basal cells little if at all differentiated, i. UI.OTHRIX. i. ULOTHRIX Kiitzing, 1833, p. 517. Filaments of a single series of uninucleate cells, all similar, and, with the exception of the attached basal cell, capable of division and of producing spores. Chromatophore band-shaped, with one or more pyrenoids. Asexual reproduction by aplano- spores and akinetes, also by 4-ciliate zoospores, with red stigma, formed 1-4 in a cell, germinating immediately; sexual repro- duction by biciliate zoogametes formed 8 or more in a cell, germinating after conjugation. External conditions may induce many modifications of the normal process ; resting spores may be formed, ultimately producing zoospores ; filaments may break up into individual cells, and these by copious formation of gelatine pass into a Palmella or a Gloeocystis condition. 182 TUFTS COLLEGE STUDIES, VOL. II, No. 3 A genus of marine and fresh water species, of world-wide dis- tribution ; by no means easy to distinguish from species of Hor- jniscia, Chactomorpha, etc., whose filaments are also of a single series of cylindrical or somewhat inflated cells. The number of nuclei can be ascertained only by careful examination, and while the shape of the chromatophore is of a different type in each genus, the variations from the type are many and perplex- ing. In herbarium specimens the chromatophore characters are usually indistinct. In general, Chactomorpha is firmer and stiffer, and has longer cells than Ulothrix ; none of our species of Ulothrix exceeds 50 /A cliam., while few species of Chaetomor- pha are less than 100 /u diam. Hormiscia species also are usually of larger dimensions than Ulothrix species, but there is little difference in cell length or consistency. As between the two genera, the only tests are the number of nuclei, requiring pretty careful study, and the form of the zoospores, ascertain- able only occasionally. As regards dried specimens, only per- sonal acquaintance with the various species, or comparison with authentic specimens, is of any use. KEY TO THE SPECIES OK ULOTHRIX. i. Marine or brackish. 2. i. Fresh water. 5. i. Thermal. 2. U. caldaria. 2. Occasionally branching. 12. U. laetevirens. 2. Always simple. 3. 3. Cells usually much shorter than their diameter. 10. U. flacca. 3. Cells usually longer than their diameter. 4. 4. Chromatophore a more or less complete ring at the middle of the cell. 9. U. implexa. 4. Chromatophore a curved lateral disk, extending from the pyrenoid in all directions, but not filling the cell. n. U. subflaccida. 5. Filaments not over 9 M diatn.; pyrenoid single. 6. 5. Filaments 1 1-45 /x diam.; pyrenoids several. 7. 6. Filaments 7-9 M diam. 3. U . tcnarima. 6. Filaments 5-6 /j. diam. i. U. rariabilis. 7. Mature filaments 25-45 M diam. 8. U. zonata. 7. Filaments not over 20 fj. diam. 8. 8. Filaments torulose. 6. U. moniliforntis. 8. Filaments not torulose. 9. 9. Cells 1-2 diarn. long. 7. U. aequalis. 9. Cells not over \ diarn. long. 10. THE GREEN ALGAE OF NORTH AMERICA 183 10. Cells 15-20 //. diatn. 4. U. tenuissima. 10. Cell ii /x cliam. 5. U. oscillarina. 1. U. VARIABILIS Kiitzing, 1849, p. 346; Hazen, 1902, p. 152, PI. XXI, figs. 5-7 ; P. B.-A., Nos. 1022, 1373 ; ? U. subtilis var. variabilis Wolle, 1887, p. 136, PL CXVIII, figs. 15-16. Filaments 5-6 //. diam., cells cylindrical, ^2-1 ^ diani. long, wall very thin and delicate ; chromatophore usually occupying about half the cell wall, often quite irregular in shape and position ; pyrenoid single, small. Europe. This species forms floccose masses in brooks and quiet waters. It has been reported from Greenland, a few localities in the- eastern States, from Trinidad, and from California. 2. U. caldaria (Kiitz.) nov. comb. ; Gloeotila caldaria Kiitz- ing, 1849, p. 363.; 1853, p. 10, PI. XXXII, fig. 3; U. subtilis var. thermarum Wolle, 1887, p. 136, PL CXVIII, figs. 18 and 19; Hormiscia flaccida var. caldaria Tilden, Amer. Algae, No. 130. Filaments soft and mucilaginous, bright or dull green, 5-8 p- diam., cells 1-3 diam. long, cylindrical; chromatophore (in dried specimens) apparently occupying the entire cell wall. Forming long strings and floccose masses in warm or hot water. Yellowstone Park ; Pa. Europe. Our only distinctly thermal species. 3. U. TENERRIMA Kiitzing, 1843, p. 253, PL IX, fig. i ; Hazen, 1902, p. 151, PL XXI, figs. 3 and 4; P. B.-A., No. 1468. U. subiilis var. tenerrima Wolle, 1887, p. 136, PL CXVIII, fig. 17. Forming light green silky masses, often of considerable length; filaments 7-9 /x diam.; cells cylindrical, J/3 -i J/3 diam. long; wall very thin; chromatophore zonate, or contracted to one side of the cell ; pyrenoid single. Vt, Mass., Cal. Europe. The single pyrenoid seems to distinguish this species from all others except U. variabilis ; these two species are certainly quite near each other, but U. tenerrima is a larger species, with the chromatophore more fully and regularly developed. The material from California distributed "as P. B.-A., No. 1468, is in the Gloeocystis state, and its connection with this species though probable is not certain. 4. U. TENUISSIMA Kiitzing, i833a, p. 518; Hazen, 1902, p. 149, PL XX, figs. 5 and 6; P. B.-A., No. 1021. Filaments dark green, 15-20^, rarely 25 /xdiam.; cells cylindrical, except when fruiting, about ^ diam. long; chromatophore a broad band. 184 TUFTS COLLEGE STUDIES, VOL. II, No. 3 This species resembles young conditions of U. zonata, and even Hazen, on whose authority it is given, is in doubt if it may not have to be included in the commoner species when bet- ter known. The distinctions are in the darker color, thinner cell wall and shorter cells, characters which are notoriously va- riable in this genus. The only localities are near New York city and in Alaska. Europe. 5. U. OSCILLARINA Kutzing, 1845, p. 197; ? Wolle, 1887, p. 137, PI. CXVIII, figs. 34-36; Hazen, 1902, p. 150; P. B.-A., No. 613. Forming soft mucilaginous masses; filaments about ii /u. diam.; cells /^-/^ diam. long, rarely i diarn.; chromato- phore a broad band. Mass. Europe. In quiet or slowly running water. The short cells and soft, mucilaginous consistency are the chief distinguishing characters. Wolle reports it from Wisconsin, but if his figure is drawn from Wisconsin specimens, there might be some question as to the identity of his plant with the present species. Hazen reports the specimens in the Wolle herbarium not to be Ulothrix. U. oscillarina appears to be a plant of summer rather than of spring. 6. U. MONILIFORMIS Kiitzing, 1849, p. 347 ; 1852, PI. LXXXVIII, fig. 4; Hazen, 1902, p. 157; P. B.-A., No. 612. Filaments 11-14 f- diam., more or less crisped, torulose, light green, with thick walls ; cells about as long as broad. Europe. This may be the fruiting condition of •some other species, but it has not yet been identified with any, and it is quite distinct in form from any of the species here recorded. It has only one authentic locality with us, in Conn. 7. U. AEQUALIS Kiitzing, 1845, p. 197 ; Wolle, 1887, p. 134, PI. CXVIII, figs. 3-5 ; Hazen, 1902, p. 150 ; Phyk. Univ., No. 577. Filaments 13-16 /Adiam., cylindrical, cells 1-2 diam. long. Europe. A rather imperfectly known species, but considered quite dis- tinct by Hazen. The only definite locality is near New York City. 8. U. ZONATA (Web. and Mohr) Kiitzing, i833a, p. 519; Wolle, 1887, PL CXVII, figs. 1-19; Hazen, 1902, p. 147, PL XX, figs. 1-4; P. B.-A., Nos. iga and 1023. Forming yellow- ish green masses; filaments usually 30-40 \*. diam., sometimes as low as 11 //. at the base of young filaments, rarely 45 /j. in old THE GREEN ALGAE OF. NORTH AMERICA 185 filaments; cells cylindrical or somewhat swollen, ^i-i^> diam. long when full grown, longer in young filaments ; cell wall at first thin, growing thicker ; chromatophore a broad or narrow band at the middle of the cell, with several large pyrenoids. Fig. 64. Greenland, Northern U. S. from Me. to Alaska. Europe. A common species in spring, attached to sticks or stones in streams or pools ; the filaments are nearly the same diameter throughout, or smallest at the base, considerably larger above ; the cells are usually actually as well as relatively longer near the base. It is not likely to be mistaken for other fresh water species of Ulothrix, but it is not unlike Microspora crassior and M. amoena, which occur in similar stations. The characters of the chromatophores and of the cell wall can be depended on for distinction in the living plant. 9. U. IMPLEXA Ktitzing, 1849, p. 349 ; 1852, PI. XCIV, fig. 2 ; Hazen, 1902, p. 153, PI. XXI, figs, i and 2 ; P. B.-A., No. 115. Forming light green, soft masses, cells 6-15 ^ diam., sometimes slightly swollen at the middle, about as long as broad, chromatophore occupying only the middle part of the cell, often an incomplete ring. Atlantic coast and Alaska. Europe. Rather common from New Jersey to Greenland, usually near high water mark, and where it is more or less exposed to the in- fluence of fresh water ; most frequent in spring. Reported from Florida by Wolle, but the identification is doubtful. 10. U. FLACCA (Dillw.) Thuret in L,e Jolis, 1863, p. 56; Farlow, iSSi, p. 45; Hazen, 1902, p. 155, PL XX, figs. 7-9; P. B.-A., Nos. 17, 1123; Hormotrichum speciosum and H. bore- ale Harvey, 1858, p. 90. Forming bright or dark green, often much entangled masses or skeins ; cells 10-25 /"• diam., %-y\ as long as broad ; when producing spores up to 50 /j. broad, and swollen in the middle ; chromatophore occupying the whole of the cell wall. Atlantic and Pacific coasts. Europe. Common between tide marks from New Jersey to Greenland, and occurring on the Pacific coast from Washington to Califor- nia ; in southern New England chiefly on Fitcus and Spartina (Hazen, 1902, p. 156) ; more northerly, abundant on rocks and woodwork, often forming, in company with Hormiscia penidlli- formis and Bangia fusco-purpurea, a band along the shore be- 1 86 TUFTS COLLEGE STUDIES, VOL. II, No. 3 tween half tide and low water mark, for a long distance. It is most abundant in winter and spring, but is found more or less throughout the year. Several species have been segregated by Wille, 1901, from U. flacca ; the new species are not at all easy to distinguish, except when living ; probably all have passed as forms of U. flacca in this country. The most certain marks of this species are the always free filaments, with short cells, quite occupied by the chromatophore, which is of nearly even thick- ness throughout. n. U. SUBFLACCIDA Wille, 1901, p. 27, PI. Ill, figs. 90- 100 ; P. B.-A., No. 1275. Filaments 5-25 p. diam., attached by a rounded basal cell ; cells 1-2 diam. long, rarely more or less ; chromatophore a curved parietal disk, with one pyrenoid ; zoospores formed 8 in a cell, broadly ovoid. Segregated from U. flacca by Wille, this species is to be rec- ognized chiefly by the longer cells, with the chromatophore quite thick at one side, where the pyrenoid is situated, thinner in all directions, often not extending around the cell or to the ends. The only locality with us is at California, where it was found growing on a steamer whose daily route passed from fully salt to fully fresh water. Such exceptional conditions would naturally have their results on the plant, and it is of course possible that under more normal conditions it would be different. At present it answers well to Wille's species. 12. U. laetevirens (Klitz.) nov. comb. ; Schizogonium laete- virens Kutzing, 1845, p. 194; P. B.-A., No. 313. (?) U.conso- ciata Wille, 1901, p. 25, PI. II, figs. 82-89. Filaments 10-25 p. diam., two or three often firmly grown together laterally, more or less entangled and creeping ; with not infrequent branches, issuing at a wide angle, and usually much more slender than the main filament, of many cells, which are generally 1-3 diam. long ; filaments tapering towards the base, the lower cells of the densely packed filaments often subparenchymatously united ; cells y±-Y\ diam. long, rarely more; chromatophore covering nearly or quite all of the cell wall, but thicker at one side, where the pyrenoid is situated ; zoospores usually 8 in a cell ; akinetes formed singly from the cells. On woodwork between tides. Canada, Me., Cal. Europe. The Canadian plant grew on alder logs at Cap a 1'Aigle ; the material distributed as P. B.-A., No. 313, on fence rails be- THE GREEN ALGAE OF NORTH AMERICA 187 tween tide marks, at Eagle Island, Penobscot Bay, Maine. This material agrees very well with authentic specimens of Schizogonium laetevirens from Calvados, the locality given by Kiitzing ; whether Bangia laetevirens Harvey in Hooker, 1833, p. 317, is the same, can hardly be determined ; that species is ignored by Harvey in his later works. The description of U. consociata Wille would seem to indicate the same species. It is our only species of this genus with branching filaments ; the laterally united filaments are also characteristic, resembling those of Schizogonium ; they arise, however, by the union of distinct filaments, not by longitudinal division of a single filament. The genus Hormospora Brebisson, has cells practically like those of Ulothrix, but located at a greater or less distance from each other in a relatively large gelatinous filament. Several species have been described, but Cienkowski, 1876, has shown that under certain conditions a species of Ulothrix passed into a state agreeing perfectly with the description of Hormospora, and then by further development into a Palmetto, state. Gay, 1891, states that he has examined a number of authentic speci- mens of the original species, H. mutabilis Breb., and found all stages from normal Ulothrix to typical Hormospora. At least four species in this genus were proposed by Wolle at different times, but in Wolle, 1887, pp. 133, 189, he appears to have given up his belief in them. In PI. CXXIV of the same work are figured a number of forms, one of which, H. purpurea Wolle, 1880, p. 22, seems to be a good species, but until more is known of its life history, its affinities must be doubtful, but with a prob- ability that it belongs with the Rhodophyceae , among the Bangi- aceae. It has been distributed from Pa. in Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 1358, and from N. H. in P. B.-A., No. 1374. Fig. 65. The only other species for which there is a record in this region has recently been described by G. S. West, who thinks that the genus should be maintained, at least provision- ally. As this species is quite different from species previously described, and, if a condition of Ulothrix, probably related to i88 TUFTS COLLEGE STUDIES, VOL. II, No. 3 some undescribed species, it appears well to give the descrip- tion here. H. SCALARIFORMIS G. S. West, 1905, p. 282, PI. CCCCL.XIV, figs. 6 and 7. Cells narrowly oblong-ellipsoid, rather distant, 7-8.5 by about 2.5 /x, set transversely in the cylindrical, gelati- nous filaments, 13-17 p- diam. Barbados. 2. URONEMA L,agerheim, 1887, p. 517. Filaments attached, simple, of a single series of cells, apical and basal cells attenuate ; chrornatophore a parietal disk, with two pyrenoids, rarely only one pyrenoid ; asexual reproduction by 4-ciliate zoospores produced singly, sometimes two, in any cell of the filament, escaping by an opening, germinating at once ; also by aplanospores, formed one in a cell. Only one species. U. CONFERVICOLA Lagerheim, 1887, p. 518, PL XII, figs, i-io; Wittr. and Nordst., Alg. Exsicc., No. 910. Filaments up to i mm. long, solitary, cylindrical, apical cell acuminate, basal cell attenuate, terminating in a callus; cells 4-6 p. diam., 2^-4 diam. long, basal and terminal cells considerably longer; usualh^ attached to other algae. Fig. 66. W. I., Cal. Europe. Gaidukow, 1903, claims that under certain conditions a plant that he designates as Ulothrix flaccida var. genuina Hansgirg, developed filaments with pointed ends ; and that therefore Uro- nema should be, at most, merely a subgenus of Ulothrix. There might be some question as to what species Gaidukow had under investigation ; Hansgirg gave a very broad extension to Ulo- thrix flaccida, and his views on polymorphy of algae are well known ; as here understood, Ulothrix flaccida Kiitz. belongs in the genus Stichococcus, having only one pyrenoid to a cell, bicil- iate asexual zoospores, and no differentiated basal cell. This certainly does not agree with Uronema, and as U. confervicola has been found in very distant stations, practically the same, it seems best to retain it, pending further developments. 3. RADIOFILUM Schtnidle, 1894, p. 47. Cells usually not as long as broad, subglobose, ellipsoid or lenticular, with parietal chrornatophore and one pyrenoid, ar- ranged in longitudinal series, in a wide, gelatinous, cylindrical sheath. R. APICULATUM W. and G. S. West, 1895^ p. 52 ; Bohlin, THE GREEN ALGAE OF NORTH AMERICA 189 1897, p. 10, PI. I, figs. 6-8; P. B.-A., No. 1421. Cells lenticu- lar with sharp edge, about 6 ^ diam., 4 /u, thick, set transversely in a transparent gelatinous sheath, 20-25 V- diam. Fig. 74. Mass. So. Atncn'cu. The filaments of this species are found among various unat- tached algae in quiet water. The cell wall appears to consist of two equal parts, something like two soup plates set face to face ; in the filament these show the edge view, the outline being an oval with acuminate ends. 4. SCHIZOMERIS Kutzing, 1843, p. 247. Frond filiform, unbranched, of a single series of cells below, increasing in size above, cells dividing in all directions ; repro- duction by biciliate zoospores with red stigma ; asexual (?). Fresh water. Only one species. S. L,EIBLEINII Kutzing, 1843, p. 247, PI. XII, fig. i ; Wolle, 1887, PI. CXXV. ; P. B.-A., No. 69. Frond up to 20 cm. high, rather stiff, 20-25 M diam. at base, up to 150 ^ above; terete below, with more or less deep and frequent constrictions above; cells 15-30 //. diam., roundish or angular, with rather thick, often lamellate membrane ; zoospores formed in the upper part of the frond, freed by the breaking of the cross walls, the side walls dissolving later ; zoospores thus issuing from the summit of the frond. Fig. 67. In quiet fresh water. Mass., R. I., N. J., Pa., Fla. Europe, So. America. 5. STICHOCOCCUS Nageli, 1848, p. 76. Filaments without special basal cell, slender, consisting of few or many cells ; chromatophore a parietal disk or plate, not covering more than half the cell wall, containing one pyrenoid. Vegetative reproduction by the breaking up of the filament into individual cells, which may be considered as akinetes ; asexual reproduction by biciliate zoospores without stigma, formed singly in a cell, escaping by a small hole in the wall, and ger- minating without forming a holdfast. Species of Stichoccocus occur in fresh water, rarely in salt or brackish water, and also in moist places not under water. The smaller species of Ulothrix, with chromatophore of irregular shape, are not easily distinguished from species of Stichococcus ; but the biciliate spore of the latter, the absence of a basal cell, and the tendency of the filaments to break up into individual cells, seem to justify keeping it as a separate genus. 190 TUFTS COLLEGE STUDIES, VOL. II, No. 3 KEY TO THE SPECIES OF STICHOCOCCUS. i. Cells cylindrical. 2. i. Cells swolleji. 4. 2. Plant of moist places, not submerged. i. 5. badllaris. 2. Aquatic. 3. 3. Marine. 3. S. marinus. 3. Fresh water. 6. 4. Cells usually over 5 /* diam. 4. 5. subtilis. 4. Cells usually under 5 fj. diam. 5. 5. Cells 3-3.5 fJ- diam., i-io diam. long. 2. S. scopulinus. 5. Cells 2.5-3 f- diam., 1-4 diam. long. i. S. badllaris f. confervoideus. 6. Plant of moist places, not submerged. 5. S.flaccidus. 6. Fresh water plants, submerged. 7. 7. Unbranched ; filaments readily breaking up. 6. S.fluitans. 7. With rhizoidal branches ; not readily breaking up. 7. S. rivularis. 1. S. BACILLARIS Nageli, 1848, p. 77, PI. IV. G., fig. i ; Hazen, 1902, p. 160, PI. XXII, fig. i ; P. B.-A., No. 1024. Filaments pale green, 2.5-3 ^ diam., cylindrical, of 2-24 cells, very readily separating; cells 1-4 diam. long; chromatophore elliptical, thin and pale. Fig. 69. On damp ground, rocks, and on flower-pots in greenhouses. Nova Scotia, N. H., Mass., N. Y., Kansas, N. C., Cal. Europe. Forma CONFERVOIDEUS Hazen, 1902, p. 160, PI. XXII, figs. 2 and 3. Submerged form ; filaments longer, not so readily breaking up. Found among other algae, in rather quiet water, forming crisped or floccose masses. Mass, to N. ]. 2. S. SCOPULINUS Hazen, 1902, p. 161, PI. XXII, figs. 4-6. Filaments forming long, bright green, lubricous masses ; cells cylindrical, 3-3.5 /A diam., i-io diam. long; wall very thin, chromatophore pale, slender ; pyrenoid indistinct. Slightly larger than S. badllaris forma confervoidea , and with longer cells ; at the original locality, near New York city, the only station yet recorded, it formed long skeins on dripping rocks ; when collected it soon breaks up, or produces abundant zoospores. 3. S. MARINUS (Wille) Hazen, 1902, p. 161, PI. XXI, figs. Sand 9; Ulothrix variabilis var. marina Wille, P. B.-A., No. 615. Filaments dark green ; cells cylindrical, 5-6 /A diam., cells 1-2 diam. long; chromatophore a roundish or oblong plate; pyrenoid indistinct. Me., R. I., Conn., Cal. Northern Europe. The only marine species ; much more slender than any of our THE GREEN ALGAE OP NORTH AMERICA 191 marine species of Ulothrix, which are the only plants for which it could be mistaken. 4. S. SUBTILIS (Kiitz.) Klercker, 1896, p. 103; Hazen, 1902, p. 162, PI. XXI, figs. 10-13; Ulothrix subtilis Wolle, 1887, p. 135, PI. CXVIII, figs. 9 and 10, in part; P. B.-A., No. 614. Forming extensive, bright green, lubricous masses ; filaments long, cylindrical, 5-6.5 yu, diam., rarely 8 //. ; cells 1-3 diam. long ; wall thin, chromatophore elliptical, with a small pyrenoid ; fila- ments showing little tendency to break up. Greenland, Me., Vt. to Pa., Cal. Europe. Very common in spring, especially where water is running over rocks ; also in watering-troughs and in pools ; less com- mon at other seasons. 5. S. FLACCIDUS (Kiitz.) Gay, 1891, p. 79, PI. XI, figs. 101- 106 ; Hazen, 1902, p. 164, PI. XXI, figs. 14-17 ; P. B.-A., Nos. 116, 1222; Ulothrix flaccida Wolle, 1887, p. 137, PI. CXVIII, figs. 27-28. Filaments rather short, forming floccose or inter- woven masses; cells 6-9.5 /"• diam., somewhat swollen, %-\ diam. long, occasionally up to 2 diam.; cell wall fairly thick ; chromatophore broad, with a large pyrenoid. On wet rocks and soil, and on the bark of trees. Mass., N. Y., Cal., and probably generally distributed. Europe. Only slightly larger than .5". subtilis, but with cells usually shorter, distinctly swollen, and with a thicker wall ; a plant of moist places rather than submerged. 6. S. FLUITANS Gay, 1893, p. CLXXIV, fig. i ; P. B.-A., No. 759; Hazen, 1902, p. 165, PI. XXII, figs. 7-9. Filaments yellowish green, crisped and interwoven, sometimes geniculate, with a strong tendency to break up, 6.5-9 ^ diarn., cells 1-3 diam. long ; chromatophore large and thick, nearly concealing the inconspicuous pyrenoid. Mass., N. J. Europe. In the two American localities this species occurs on smooth rocks swept by rapid water from a cascade ; the filaments are unaffected by the current, but when removed to quiet water break up into individual cells in a very short time. 7. S. RIVULARIS (Kiitz.) Hazen, 1902, p. 166, PI. XXII, fig. 10-13; Ulothrix rividaris Wolle, 1887, p. 136, PI. CXVIII, figs. 6-8, 29-33. Forming bright green tufts ; filaments some- what geniculate but not easily breaking up, 8-n ^ diam., of few cells ; giving out hooked rhizoidal branches ; cells 1-2 diam. long, somewhat swollen ; chromatophore orbicular to rhom- 192 TUFTS COLLEGE STUDIES, VOL. II, No. 3 boidal, sharply marked, pyrenoid large. On rock or earth in •rapid streams. N. H., Conn. Europe. Of about the same size as ^S. fluitans, but with filaments more distinctly geniculate, cells less easily separable, and especially characterized by the rhizoidal branches. 6. MICROSPORA Thuret, 1850, p. 221. Filaments simple, usually unattached and with no special basal cell ; chrornatophore a granular sheet covering the cell wall more or less completely, sometimes with perforations, with- out pyrenoids but with scattered starch granules. Cell wall composed of laminae, so arranged that when the filaments break up for the escape of zoospores, the pieces remain in the shape of cylinders open at both ends, with a cross wall near the middle, the so-called 'H section." Asexual reproduction by 2- or 4- ciliate zoospores, i or 2 in a cell ; also by smaller 2-ciliate zo- ospores, formed several in a cell ; both kinds germinating directly ; whether the smaller kind may also act as gametes is uncertain. Aplanospores and akinetes also formed. A widely distributed genus of fresh water algae, formerly in- cluded in Conferva, and in some respects allied to the Hetero- kontae, but on the whole nearer to the Ulotrichaceae, by the form of the chromatophore and the chemical nature of the cell contents, as well as by the form of the spores. These characters, however, are of little use except in the study of fresh material. KEY TO THE SPECIES OF MICROSPORA. i. Cells thick-walled. 2. i. Cells thin-walled. 5. 2. Cells less thati 15 M diam. 4. M. pachyderma. 2. Cells 16 M diaui. or more. 3. 3. Cells distinctly swollen. 3. M. Loefgrenii. 3. Cells cylindrical or nearly so. 4. 4. Cells 20 fj- diam., 1-2^ diain. long. 5. M. Wittrockii. 4. Cells 21-25 fj. diam., 1-2 diam. long. 2. J\I. ainoena. 4. Cells 28-33 /a diaui., 1-2 diam. long. r- M. crassior. 5. Cells ii /xdiani. or more. 6. 5. Cells 10 fji. diam. or less. 7. 6. Cells 11-14 M diam. 7- M- Willeana. 6. Cells 14-17 M diam. 6. M.floccosa. 7. Cells 5-7 M diam. 10 . M. quadrata. 7. Cells 7-9.5 ft. diam. 8. 8. Cells cylindrical. 8. M. stagnorum. 8. Cells slightly constricted. 9. Af. tuwidula. THE GREEN ALGAE OF NORTH AMERICA 193 1. M. CRASSIOR (Hansg.) Hazen, 1902, p. 169, PI. XXIII, fig. 2; P. B.-A., No. 1070; Af. amocna forma crassior Wille, 1899, p. 149. Filaments long, dark green, nearly cylindrical, 28-33 p. diani., cells 1-1.6 diam. long, with wall 2.5-3 M thick ; lamellate structure usually distinct ; chromatophore dense, covering the whole cell wall and hiding the large nucleus. The largest species of the genus, the nearest species, M. amoena, being considerably smaller, with thinner walls and rela- tively shorter cells. It forms thick tangled masses in rapid brooks, from May to October. Mass, to N. Y. Europe. 2. M. AMOENA (Kiitz.) Rabenhorst, 1868, p. 321 ; P. B.-A., No. igb as Ulothrix sonata, No. 616; Hazen, 1902, p. 170, PI. XXIII, fig. i ; Conferva amoena Wolle, 1887, p. 140, PI. CXXI, figs 1-5. Filaments long, dark or bright green, nearly cylindri- cal, 21-25 M diam.; cells 1-2 diam. long, with wall about 2 p. thick ; chromatophore dense, covering the whole cell wall, and hiding the quite large nucleus. In rapid brooks, forming more or less tangled, often quite long masses, April to July. Mass, to N. J. Europe. 3. M. LOEFGRENII (Nordst.) Lagerheim, 18873, p. 417 ; Hazen, 1902, p. 171, PI. XXIII, figs. 3 and 4; Wittr. and Nordst., Alg. Exsicc., No. 17. Filaments long, 16-20 p. diam., cells distinctly swollen, 1-2 diam. long, wall about 2.5 p. thick ; chromatophore dense, covering the whole cell wall, concealing the nucleus. N. Y., Mass. Europe, So. America. Smaller than M. amoena, and with distinctly swollen cells; but otherwise of the same character as that species and M. cras- sior. 4. M. PACHYDERMA (Wille) L,agerheim, 18873, p. 415; Conferva pachyderma Wille, 1881, p. 13, PI. IX, figs. 28-35. Filaments 8-14 /*diam., cells i/^'3 diam. long, wall up to 3 p. thick; akinetes rounded-quadrate to ellipsoid, not larger than the vegetative cells. Greenland. Europe. 5. M. WITTROCKII (Wille) Lagerheim, iSSya, p. 417; Hazen, 1902, p. 172, PI. XXIII, figs. 5-7; Wittr. and Nordst., Alg. Exsicc., No. 422. Filaments long, silky, light green, per- fectly cylindrical, about 20 p. diam.; cells 1-2^2 diam. long, wall about 1.5 /* «thick, not distinctly lamellate: chromatophore thin, often perforated, or not occupying the full length of the cell, the large nucleus usually quite distinct. Vermont, Mass., N. Y. Europe. A more delicate plant than any of the preceding species and apparently common in early spring, often in company with M. stagnorum . 194 TUFTS COLLEGE STUDIES, VOL. II, No. 3 6. M. FLOCCOSA (Vauch.) Thuret, 1850, p. 222, PI. XVII, figs. 4-7; Hazen, 1902, p. 173, PL XXIV, figs. 1-4; P. B.-A., No. 864. Conferva floccosa Wolle, 1887, p. 140, PI. CXX, figs. 21-25. Filaments bright or yellowish green, cylindrical or very nearly so, 14-17 (rarely 18) //.diam.; cells 1-2^2 diam. long, with thin walls ; chromatophore pale green, often perforated or in net form ; akinetes 18-22 /u. diam., sphaeroidal, cuboidal or subcylin- drical. Fig. 68. Mass, to N. J., Vancouver I. Europe. A very common spring plant, forming loose floccose masses in slow streams and quiet waters. 7. M. WILLEANA Lagerheim in De Toni, 1889, p. 228; Hazen, 1902, p. 17-5, Pi. XXIV, figs. 5-7; P. B.-A., Nos. 619, 1326. Filaments cylindrical, light green, 11-14^, diam.; cells ^2-1^2 (rarely 2) diam. long, wall thin ; chromatophore vari- able, but usually denser than in M. floccosa ; akinetes 14-16.5 /u, diam., spherical to subcylindrical. Mass, to N. J., Alaska, Cal. Europe. Occurring in the same localities as M. floccosa, and much re- sembling the latter, but with somewhat smaller filaments and decidedly smaller akinetes. 8. M. STAGNORUM (Kiitz.) L,agerheim, 1887 a, p. 417; Hazen, 1902, p. 176, PI. XXIV, figs. 12-13 ; P- B.-A., No. 618. Filaments cylindrical, 7.5-9.5 (usually 8) /x diam., cells 1-3 diam. long, wall thin ; chromatophore not dense, and often occupying only the middle part of the cell. Greenland, Maine to N. J. Europe, So. America. A common species of early spring, but occurring also in summer and autumn, often in company with other species of Microspora or Ulothrix. 9. M. TUMIDULA Hazen, 1902, p. 177, PI. XXIV, figs. S-n ; P. B.-A., Nos. 1025, 1277. Filaments with distinct constrictions at the dissepiments, 6.7-9.5 (usually 7.5) p. diam. ; cells 1-2 diam. long ; chromatophore rather dense, nearly or quite cover- ing the cell wall ; akinetes S-n ^ diam., spherical or flattened. Greenland, Mass., to N. J., also at Banff, Canada. Forming dull green skeins or floccose masses in brooks and pools ; much like I\l. stagnorum, from which it is distinguished by the distinctly contracted dissepiments and the more uniform chromatophore. 10. M. OUADRATA Hazen, 1902, p. 178, PI. XXIV, figs. 14 and 15; P. B.-A., No. 1276. Filaments light green, perfectly cylindrical, 5.5-7 /^ diam. ; cells >^-i diam. long, with very thin THE GREEN ALGAE OF NORTH AMERICA 195 wall ; chroniatophore a fine even coating over all the cell wall, often including the dissepiments. Vermont and Mass, to N. Y. Forming light green floccose masses, in still or slow water ; has been collected from May to October, which would seem to indicate less of a spring plant than most species of Microspora. Its very fine filaments with short cells distinguish it quite clearly from our other species. Family 2. ULVACEAE. Membranaceous, plane, or tubular fronds ; cells uninucleate, with disk-shape chromatophore and one pyrenoid ; asexual re- production by 4-ciliate zoospores (sometimes biciliate ?) ; sexual reproduction by biciliate gametes. The membrane is in the form of a tube, a sac, or a flat expan- sion ; in the latter case it may consist of one or two layers of cells ; in the simplest forms there may be merely two rows of cells side by side, or in some parts of the frond, only a single series of cells. Spores and gametes may be formed in any cell of the frond except the lowest cells, which may send down rhizoidal prolongations, uniting to form a stipe. Of world-wide distribution ; marine, rarely fresh water plants ; usually gregarious, often growing in great quantities. They are specially plants of the literal zone, occasionally extending down for a short distance into the sublitoral. KEY TO THE GENERA OF ULVACEAE. T. Frond tubular, rarely of one or two series of cells. 2. i. Frond tubular only in the early stages, if ever. 3. 2. Frond gelatinous ; cells in loosely united longitudinal series. 2. ILEA. 2. Not specially gelatinous; membrane parenchymatous. i. ENTEROMORPHA. 3. Minute ; adherent by the entire lower surface. 5. PROTODERMA. 3. Larger; adherent only at the base. 4. 4. Frond of a single layer of cells. 3. MONOSTROMA. 4. Frond of two layers of cells. 4. UI/VA. i. ENTEROMORPHA Link, 1820, p. 5. Frond originating in a single series of cells, which by re- peated division form a tubular frond, the membrane of which consists of a single layer of cells ; in some of the simpler species the tubular stage is not reached, and the frond in the adult state consists of two or a few series of cells, united without any 196 TUFTS COLLEGE STUDIES, VOL. II, No. 3 interior space. All the cells of the frond, except the lowest, capable of producing zoospores or gametes, which are dis- charged through an opening in the cell wall. A large genus, connected with Ulva by E. linza, in which the tube is compressed, and the membranes united in the median part ; on the other hand, Monostroma grocnlandicinn is hardly to be distinguished from some of the simple filiform species of Enteromorpha. E. intestinalis is found the whole world over, and other species are very widely distributed. They are found not only in the sea, but about salt springs and salt mines ; they abound in brackish water, and are occasionally found in quite fresh water. At places whe.^ the salinity of the water is subject to much change, very perplexing forms occur ; specimens collected near the salt mines at Syracuse, N. Y., show in the same frond char- acters of E. compressa, E. crinita, and E. marginata. It is impos- sible to- say what is the normal form ; the specimens must be considered as teratological. Specimens from Great Salt Lake, Utah, also show abnormal forms. KEY TO THE SPECIES OF ENTEROMORPHA. I. Frond flat, the membranes free at the margins, but united between. 19. E. linza. I. Frond of one to a few series of cells, not tubular. 2. i. Frond tubular. 3. 2. Frond simple. i. E.percursa. 2. Frond branched. 2. E. cruciata. 3. Cells not arranged in longitudinal series except in the very youngest parts. 4. 3. Cells more or less in longitudinal series, usually in the greater part of the frond. 9. 4. Cells of the new generation in twos, threes and fours, in the wall of the mother cell. 16. E. fascia. 4. Mother cell wall not persisting after division. 5. 5. Frond with short, spine-like ramuli, in addition to branches. 8. E. acanthophora. 5. Frond with more or less plentiful branches. 6. 5. Frond simple or with a few proliferations. 7. 6. Frond with flattened rachis branching from the margin. 17. E. micrococca var. subsalsa. 6. Frond filiform ; branches with contracted base, expanding upwards. 10. E. compressa. THE GREEN ALGAE OF NORTH AMERICA 197 7. Cells 10-16 /j. diatn. ; fronds usually inflated and constricted ; often of large size. 18. E. intestinalis. 7. Cells 4-8 i*. diam. ; fronds usually short. 8. 8. Membrane 8-10 /x thick ; cells 5-7 fj. diam. n. E. minima. 8. Membrane 15-20 fj, thick ; cells 4-5 M diam. 17. E. micro cocca. 9. Fronds simple, inflated and flexuous. 15. E.flexuosa. 9. Fronds simple or with occasional proliferations ; not inflated. 10. 9. Fronds regularly branched. n. 10. Frond narrowly linear, strongly compressed. 13. E. marginata. 10. Frond filiform, 2-8 cells wide, tubular only in the widest parts ; branches two cells wide. 3. E. torta. 10. Frond filiform, tubular, of uniform diameter; of numerous series of squarish cells. 14. E. prolifera var. tubnlosa. ii. Frond beset with numerous thorn-like branches. 12. E. salina var. polyclados. ii. Branches proliferous, similar to main filaments. 14. E. prolifera. ii. Branches of successive orders, tapering from base to apex. 12. 12. Chromatophore filling cell. 13. 12. Chromatophore not filling cell, giving a net-like appearance. 14. 13. Ultimate ramuli short, spine-like, not nionosiphonous. 9. E. ramtilosa. 13. Ultimate ramuli of a single series of cells. 6. E. crinita. 13. Ultimate ramuli polysiphonous, of a few symmetrically placed series of cells. 7. E. erecta. 14. Ultimate ramuli of a single series of cells. 4. E.phimosa. 14. Ultimate ramuli not of a single series of cells. 5. E. clathrata. i. E. PERCURSA (Ag.) J. G. Agardh, 1842, p. 15 ; P. B.-A., Nos. 469, 968 ; Tetranema percursum Areschoug, 1846, p. 192, PL II. A. Frond filiform, in the earliest state of one row, afterwards of two rows of cells, placed symmetrically side by side ; cells 10-15 f- wide, from once to twice as long. Greenland to N. J. ; Alaska to Cal. Europe. A common species, forming masses in upper tide pools, and in ditches in marshes, etc. It often grows in company with other species, but is easily distinguished on microscopic exam- ination by the double row of cells, usually in exact symmetry, side by side. The small chromatophores occupy only part of the cell room, giving the same net-like appearance found in E. clathrata. 198 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. E. CRUCIATA Collins, 1896, p. 3 ; 1903, p. 27, PI. XLIII, fig. i ; P. B.-A., No. 222. Frond filiform, branching, mostly of a single series of cells, but at the points of branching often of two or more series ; branches issuing at right angles or nearly so, usually opposite but sometimes alternate or secuncl, simple, usually short, tapering ; rnonosiphonous portions 20-30 // diam- eter ; cells about as long as broad, cell wall thick; in the irregular masses, where several branches issue near together, the cells are rounded and sometimes reach a diameter of 50 p. This plant is very different from other species of Enteromor- pha, the nearest being E. percursa ; but E. cruciata has nothing of the symmetry and uniformity that especially characterize E. percursa. The monosiphonous parts with few and short branches remind one somewhat of Rhizodonium, but the branches are often of many cells, and wherever several branches issue near the same point, an irregular mass of cells is formed. It was found in a lagoon at Eagle Island, Penobscot Bay, Maine, connecting with the sea only at excep- tionally high tides, in floating masses in company with Clado- phora expansa, Lyngbya, etc., in July, 1894, aud is not known elsewhere. 3. E. TORTA (Mert.) Reinbold, 1893, p. 201 ; P. B.-A., No. 223. Frond filiform, compressed, simple or with occasional long proliferous branches, which usually consist of only two rowys of cells ; cells rectangular, always in longitudinal and mostly in cross series. Me., Barbados. Europe. A very slender species, the main filaments only 2-8 cells wide, and only in the wider forms showing any open space within. The branches are few, at wide angles, and are seldom over two cells wide. They resemble somewhat the fronds of E. percursa, but the cells in the latter are more symmetrically arranged ; and E. percursa is always simple and never has over two rows of cells, as do most of the older parts of this plant. 4. E. PLUMOSA Kiitzing, 1843, p. 300, PI. XX, fig. i ; E. Hopk/'rkii Harvey, 1849-51, PI. CCLXIII ; 1858, p. 58; P. B.-A., No. 463; Ulva Hopkirkii Farlow, iSSi, p. 44. Frond filiform, cylindrical or somewhat compressed, very slender and delicate, much and repeatedly branched, the branches tapering and ending in a single series of cells ; cells about 8 p. wide in the monosiphonous part, below about 1 2 X 20 /u,, with THE GREEN ALGAE OF NORTH AMERICA 199 quite small chromatophores ; always in longitudinal and often in transverse series. Me. to W. I. Europe. One of the most attractive of our Enteromorphas both in habit and microscopically. There are other species which occasion- ally have short monosiphonous branches, but in E. plumosa nearly every young branch terminates in a monosiphonous series of considerable extent. Common in northern New England, growing largely on Cladophora glaucescens and on rocks and shells in rock pools ; also in quiet bays. 5. E. CLATHRATA (Roth) Greville, 1830, p. 181 ; P. B.-A., No. IvXXVIII ; Ulva clathrata Farlow, 1881, p. 44. Frond fili- form, cylindrical or compressed, much branched in all direc- tions, the branches tapering from base to summit, but not end- ing in a single series of cells ; cells rectangular, usually longer than broad, always in longitudinal series, the chromatophore noticeably smaller than the cell. Me. to W. I.; Alaska. Europe ', Tasmania, New Zealand. A species of warm quiet waters, where it often forms great floating masses ; it differs from most other species in having a real system of branching of various orders ; also in the chroma- tophore smaller than the cells. From E. plumosa, which agrees with it in these particulars, it differs by the absence of mono- siphonous ramuli. It is common at some points in southern Mass., and probably along the coast to the south ; but so many forms have been included under this name in older records, that few localities are certain. It is not common north of Cape Cod. Ulva clathrata var. Rothiana forma prostrata Farlow, 1881, p. 44, P. B.-A., No. 459, seems nearer to E.prolifera. 6. E. CRINITA (Roth) J. G. Agardh, 1882, p. 144 ; P. B.-A., Nos. 460, 965, 1325. Frond filiform, cylindrical or compressed, much and repeatedly branched, the branches tapering, the smallest usually of a single series of quite short cells ; cells al- most always in longitudinal series, often rounded, quite or nearly filled by the chromatophore. Me. to N. J.; Gulf of Mex- ico, Alaska to Cal. Europe. In habit this common marine species resembles E. clathrata, but the latter lacks the short-celled monosiphonous ramuli ; monosiphonous ramuli are found in E. p/i/inosa, but the net-like cells of the latter are quite distinct from the cells of E. crhiitn, which resemble those of E. prolifera, though somewhat smaller. 200 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The material distributed as P. B.-A., No. 1325, was from a station once connected from the sea, but cut off for several years, the water becoming quite fresh. The Enteromorpha grew in company with species of Oedogonium, Spirogyra, and other fresh water genera, and was as abundant as ever, the only noticeable change being a greater development of the mono- siphonous part in proportion to the rest. 7. E. ERECTA (L,yng.) J. G. Agardh, 1882, p. 152 ; P. B.-A., No. 461. Frond filiform, with numerous long, usually erect branches, more slender than the main filament ; the ulti- mate ramuli of varying length, polysiphonous, the cells being symmetrically arranged in successive segments, similar to those of Polysiphonia ; cells in the main stem and branches in longi- tudinal and usually in transverse series. Fig. 70. Me. to W. I. Europe. The most distinctive character of this species is found in the polysiphonous ramuli ; in habit it is not unlike E. crinita, but the cells of E. erecta are usually more symmetrically arranged in the older parts of the frond, and more rectangular. It is not uncommon as a plant of exposed shores. 8. E. ACANTHOPHORA Kiitzing, 1849, p. 479; 1856, p. 12, PI. XXXIV, fig. i ; P. B.-A., No. 515. Frond more or less proliferously branched, the branches usually somewhat enlarged upwards, beset with numerous short, spine-like ramuli, with broad base and acute tip ; cells 6-8 /A diam., roundish angular, showing no longitudinal arrangement except indistinctly at the tips of the ramuli ; marine and fresh water. Cal., at shore, and in mountains up to 300 meters. So. America, New Zealand. Somewhat resembles E. ramulosa, but the cells are much smaller, with hardly any indication of longitudinal arrangement ; the substance is less firm, and the color is lighter. The fronds seem to collapse irregularly in drying. The spine-like ramuli vary in abundance, sometimes almost covering the frond ; the regular branches are not very numerous, and seem quite dis- tinct from the ramuli. 9. E. RAMULOSA (Eng. Bot.) Hooker, 1833, p. 315 ; Har- vey, 1849-51, PI. CCXLV ; Ulva clathrata var. ramulosa Far- low, 1 88 1, p. 44. Frond tubular, rather stiff, much branched; branches with short, spine-like ramuli ; cells rather rounded, showing longitudinal series only in the ultimate divisions. Mass, to W. I. Europe, New Zealand, Australia^ THE GREEN ALGAE OF NORTH AMERICA 201 A coarse species, readily recognized by its habit. It appears to be not uncommon on the southern part of the Atlantic coast, but rare in New England. The color is usually a rather deep or dark green ; the main branches are quite long, and are everywhere beset with short, tapering ramuli ; the cells are rounded, almost entirely occupied by the chroniatophore ; with- out any definite arrangement, except in the ramuli. 10. E. COMPRESSA (L,.) Greville, 1830, p. 180, PL XVIII. Frond tubular, more or less compressed, sometimes constricted, varying much in dimensions ; branches usually simple, cylin- drical or expanding above, in either case narrowed at the base, similar in appearance to the main stem ; cells in no definite order; membrane rather thin. Greenland to N. J.; Alaska to Cal. Europe, So. America, Tasmania. A variable species, but now understood in a narrower sense than formerly, and including only forms with branches con- tracted at the base, with cells 10-15 /* diam., arranged in no definite order, and with membrane not thickened. Forma SUBSIMPLEX J. G. Agardh, 1882, p. 137; P. B.-A., No. 964. Frond hardly branched, of uniform diameter. Me. Europe. 11. E. MINIMA Nageli in Kiitzing, 1849, p. 482 ; 1856, p. 16, PI. XLIII, fig. 3 ; P. B.-A., Nos. 468, 912. Frond i-io cm. long, 1-5 mm. broad, simple or slightly proliferous, soft and delicate, membrane S-io /A thick, cells angular, 5-7 ^ diam., arranged in no definite order. Greenland to Conn.; Alaska to Mexico. Europe, So. Pacific. A small species, resembling E. compressa, but smaller in di- mensions of fronds and size of cells. It is probably common, but is easily overlooked among the larger and better known species of the genus. The extreme thinness of the frond gives it a very soft and delicate feeling to the touch, which is the best character by which to recognize it when growing. It seems to grow mostly in the lower half of the literal zone. Forma RivutARiS Collins, P. B.-A., No. XXVI. Color pale, fronds to half a meter in length, substance more delicate than in the type. These differences are probably due to its place of growth, running fresh water, Alaska. Forma GLACIALIS Kjellman, 1877, p. 50; P. B.-A., No. 1183. Frond 9-13^ thick; cells 5-8 ^ diam.; forming a dense 202 TUFTS COLLEGE STUDIES, VOL. II, No. 3 coating on rocks covered only at high tide, and at other times wet with water from melting ice. Greenland ; Mass. The habitat given with the description is that of the original arctic locality ; the Mass, specimens agree with the Greenland plant, though growing in summer, free from glacial conditions. 12. E. SALINA Kutzing, 1845, p. (247; 1856, p. 13, PI. XXXVI, fig. i ; P. B.-A., No. 659. Frond filiform, tubular, with a few branches, which are sometimes opposite, of two or more rows of cells, or in the youngest of a single series ; cells quadrangular, 14-16 p. square, or slightly longer than broad, in longitudinal series throughout ; membrane thickened on both sides. Fla., Louisiana. Europe - The slender fronds with relatively large cells in longitudinal series distinguish this species with tolerable distinctness from any others within our limits. Var. POLYCLADOS Kutzing, 1845, p. 248 ; E. polyclados Kut- zing, 1856, p. 13, PL XXXVI, fig. 2. Filaments beset with more or less numerous short, horizontal, spine-like ramuli. Florida. 13. E. MARGINATA J. G. Agardh, 1842, p. 16 ; Kutzing, 1856, p. 15, PI. XLI, fig. i; P. B.-A., No. 466. Frond fili- form, compressed, simple or with a few proliferous branches ; cells 4-8 n diam., squarish, arranged in longitudinal series, very distinctly in the two or three rows at each side, less so on the middle portion. Me. to N. J. ; Great Salt Lake, Utah; Cal. Europe. A small species and apparently not common, occuring mostly on stems and roots of Spartina, etc. The color is usually quite a deep green ; the fronds are comparatively narrow, seldom over 15-20 cells wide, and the width continues quite uniform through- out a filament, the margin being straight and even. Usually the fronds are simple, but occasionally one finds a few prolifer- ous branches. 14. E. PROLIFERA (Fl. Dan.) J. G. Agardh, 1882, p. 129, PI. IV, figs. 103 and 104; P. B.-A., Nos. 470,610, 913. Frond up to several meters long and 2 cm. diameter, tubular or com- pressed, with more or less abundant proliferous branches, which are usually simple, but sometimes also proliferous ; branches varying much in length and diameter; cells 10-12 n, in the younger parts always arranged in longitudinal series, which become less distinct in the older parts; membrane 15-18 THE GREEN ALGAE OF NORTH AMERICA 203 /A thick, not much exceeding the dimensions of the cells in cross section. Greenland to W. I. ; Alaska to Cal. Europe. A common species, formerly included in E. comprcssa or E. intestinalis, to the former of which it is most allied, but from which it differs in the longitudinally seriate cells, very manifest in the younger portions, and disappearing only in the quite old parts. In habit it is very variable, from slender, slightly branched forms, only a few cm. long, to richly and repeatedly branched fronds ; branches sometimes long and slender, some- times short and very densely set, sometimes long and short intermingled quite without order. It appears to prefer some- what sheltered localities where it is not left bare for any consid- erable time at low tide. It is found in fresh water in several stations in the western states, as well as about salt springs. Var. arctica (J. Ag.) nov. comb. ; E. arctica J. G. Agardh, 1882, p. 124, PI. IV, figs. 100-102. Cells smaller and rounded, membrane 20-30 p. thick, cells 10-14 /x in cross section, usually longer than broad, sometimes double their breadth. Green- land. Spitsbergen. Var. TRABECUivATA Rosenvinge, 1893, p. 961, fig. 55. More slender than the type, with long, capillary branches ; the cen- tral cavity traversed by transverse and oblique " trabeculae." Greenland. Var. TUBULOSA (Kiitz.) Reinbold, 1889, p. 117; P. B.-A., No. 471. E. tubulosa Kutzing, 1856, p. n, PI. XXXII, fig. 2. Slender, slightly branched, of nearly uniform diameter through- out. In ditches in marshes. Mass. ; Great Salt Lake, Utah ; reported from Barbados. Europe. 15. E. FLEXUOSA (Wulf.) J. G. Agardh, 1882, p. 126; P. B.-A., No. 462. Frond cylindrical, tubular, simple, taper- ing to a filiform stipe below, above inflated, flexuous and intes-' tine-like; cells 6-8X8-12 fj., roundish polygonal, in longitudinal series ; membrane somewhat thickened on the inside ; chro- matophore filling the thick-walled cell. Fla., Southern Cal. Warmer waters generally. This is a southern species, and on our Florida shores appears to take the place of E. intestinalis in the north. From the latter it differs in having somewhat smaller cells, arranged in regular series ; also somewhat more delicate membrane. From E. com- pressa it is also distinguished by the arrangement of the cells, 204 TUFTS COLLEGE STUDIES, VOL. II, No. 3 and its habit is dissimilar ; from both these species it differs in having a thicker wall between the cells. 16. E. FASCIA Postels and Ruprecht, 1840, p. 21 ; Wittr. and Nordst., Alg. Exsicc., No. 1052. Frond elongate, tubular- compressed, from a slender stipe ; sparingly branched ; cells 4-6X6-8 /A, roundish angular, in no apparent order, often -con- taining 2-4 daughter cells. Behring Sea. In the form of the frond not unlike E. intestinalis,, but with a different arrangement of cells, somewhat recalling Ilea fulves- cens. The latter, however, is much softer and more gelatinous, and the cells are arranged in longitudinal series, and more sym'- metrical in all respects. The characteristic arrangement of cells is not always distinct, and in its absence the species is dis- tinguished from E. intestinalis chiefly by the smaller cells. Can hardly be considered a well established species. 17. E. MICROCOCCA Kiitzing, 1856, p. n, PI. XXX, fig. 2 ; P. B.-A., No. 66. Fronds 1-5 cm. long, 1-5 mm. wide, tubular or compressed, simple or slightly proliferous, much curled and twisted ; cells angular, 4-5 ^ diam., in no definite order; thick- ness of membrane, 15-20 /x. Greenland to Mass. ; Alaska to Mexico. Europe. The smallness of its cells distinguishes it from all our species but E. minima, in which the dimensions are only slightly larger ; but the latter species has a very thin and delicate membrane, while in E. micrococca it is relatively quite thick, the thickening being specially pronounced on the inner side ; this gives it a coarser feeling to the touch than E. minima. Its favorite habitat on the New England coa-t appears to be on the surface of shaded, steep or vertical cliffs, < specially where the flow or drip of fresh water keeps it continually moist. Forma BULLOSA Collins, P. B.-A., No. 1067. Fronds large, irregularly inflated, to 5 cm. diam. Hal>it of E. intestinalis forma maxima, but structure of E. micrococca. Cal. Forma SUBSALSA Kjellman, 1883, p. 292, PI. XXXI, figs. 1-3; P. B.-A., Nos. 467, 1068. Rachis flattened, with numer- ous patent branches from the edges ; innch twisted and con- torted, color dark green ; growing in lagoons and marshes. Greenland, Mass., Wash. Europe. 18. E. INTESTINALIS (L.) Grevlle, 1830, p. 179; J. G. Aga dh, 1882, p. 131, PI. IV, fig. 109; Harvev, 1846-51, PI. CLIV ; P. B.-A., No. 464; Ulva Enteromorpha var. intestinalis THK GREEN ALGAE OF NORTH AMERICA 205 Farlow, 1881, p. 43. Frond simple or having at the base a few branches similar to the main frond, or occasionally a few pro- liferations above ; length varying from a few centimeters to sev- eral meters ; diameter from 1-5 cm. ; at first attached by a short, cylindrical stipe, but soon detached and floating ; cylin- drical or expanding above, more or less inflated, often much crisped and contorted, and irregularly and strongly constricted ; cells 10-16 /u diam., in no regular order; thickness of membrane varying from 50 //. below to 20 /* above ; cells in cross section from 12 to 30 /a. A common and exceedingly variable species, occurring throughout our range except on the southern Atlantic coast, where E. flexuosa appears to take its place ; also in forma tennis in fresh water. There are many intermediate forms that con- nect it with E. compressa, but in its typical form it is distin- guished by the internally thickened membrane, and by the in- testinal appearance, which is indicated by both its generic and its specific names. It is especially a plant of quiet waters, where it sometimes attains enormous dimensions. Europe, Brazil, Japan. Among the many forms of this species that have been de- scribed, the following have been recognized in America : - Forma CYLINDRACEA J. G. Agardh, 1882, p. 131 ; P. B.-A., No. 465. Frond long and slender, of uniform diameter; usu- ally floating unattached. Mass, to Conn., Alaska. Forma CLAVATA J. G. Agardh, 1882, p. 131 ; P. B.-A., No. 966. Frond attached, clavate from a filiform stipe, usually more or less contorted. N. S. to Conn.; Alaska to Cal.; in fresh water, alt. 200 meters, Cal. Forma MAXIMA J. G. Agardh, 1882, p. 132; P. B.-A., No. 1182. Floating, unattached; inflated and bullate. Me. to N. J.; Alaska. Forma TENUIS Collins, 1903, p. 23 ; E. intestinalis Tilden, Amer. Algae, No. 125. Frond attached, clavate from a taper- ing stipe ; membrane thin and delicate, not thickened within. In size and shape of cells and habit of frond, like forma clavata of salt water ; the difference in the character of the membrane may be due to the peculiar station, artesian running water. So. Dakota.* *This may be the same as E. intestinalis var. crispa Kiitzing, 1849, p. 478 ; but the description of the latter variety is insufficient to determine; " Phycomate majori inflate undulato-crispo. In aqua dulci." 206 TUFTS COLLEGE STUDIES, VOL. II, No. 3 19. E. LINZA (L,.) J. G. Agardh, 1882, p. 134, PI. IV, figs. 110-112; P. B.-A., Nos. 16,967; Ulva linza Harvey, 1846-51, PL XXXIX ; 1858, p. 59 ; U. enteromorpha var. lanceolata Far- low, 1881, p. 43. Frond lanceolate or linear-lanceolate, simple, 1-5 dm. long, 1-20 cm. broad; stipe short, hollow; upper part of the frond flat, the membranes grown together as in Ulva, ex- cept at the edges, where they remain free. Me. to W. I.; Alaska to Cal. Etirope, So. America, Tasmania. The forms of this species are divided by J. G. Agardh under forma crispata, with edges much crisped and folded, and forma lanceolata, edges even or plicate, not crisped. In one or the other of these forms the species seems common on the whole coast of the U. S.; whether extending farther south is not cer- tain. It grows on stones, woodwork and other algae, usually in places seldom or never left bare by the tide. The smaller forms look like forms of E. intestinalis, but in the latter the frond, though often collapsed, is tubular throughout; in E. linza the two membranes adhere, except at the edges, where there is a narrow open space, around which the cells are arranged, in cross section nearly in a circle. 2. ILEA Fries, 1825, p. 336. Frond filamentous, hollow, gelatinous, the cells mostly in twos and fours, enclosed within the wall of the mother cell, and arranged in distinct longitudinal series, the series loosely con- nected laterally. Only one species. I. FULVESCENS (Ag.) J. G. Agardh, 1882, p. 115 ; P. B.-A., No. 264; Enteromorpha aureola Kiitzing, 1856, p. 14, PI. XL,, fig. 3. Characters of the genus. Fig. 71. Me. to N. J.; Alaska. Europe, So. Pacific. This plant grows in dense tufts, the filaments usually 5-20 cm. long, the diam. being seldom over 2 mm., but specimens have been found one meter long, 2 cm. diam. The fronds are soft and gelatinous, the color varying from dark green to brown- ish or yellow. The cells have a distinctive Gloeocapsa-like arrangement, and are in longitudinal series so distinct that by pressure on the cover glass they readily separate, appearing like free filaments of one or two cells wide. It grows best in places where streams of fresh water empty THE GREEN ALGAE OF NOXTH AMERICA 207 into the sea, occupying the space between high and low water marks ; so that twice each day its medium is changed from sea water to quite fresh water, and back again. It appears to be common from Maine to New Jersey, and is found at salt springs at Sussex, New Brunswick, 20 miles from the sea. 5. MONOSTROMA Thuret, 1854, p. 13. Frond at first a closed tube or sac, which later opens or splits, forming a membranous expansion, of a single layer of cells, ex- cept at the base, where it is thickened, and may consist of sev- eral layers of elongated cells. Two- or four-ciliate zoospores and biciliate gametes formed in any of the cells of the monostro- matic part, issuing through an opening at the surface of the frond. In some of the species of this genus the saccate form has not been observed, but it probably occurs in all. Its persistence varies much, from M. latissimum, in which the frond forms a flat expansion when only two or three mm. high, to M. groen- landiciiDi, in which the greater part of the frond continues tubu- lar through its whole life, only the upper part opening at the time of the formation of the spores. Some of the smaller species do not exceed i dm. in length ; others, like M.jnscum, may reach 5 dm. It has representatives in all oceans, and several species inhabit by preference brackish water ; one species lives in fresh water exclusively, and some of the marine and brackish species occasionally occur also in fresh water. KEY TO THE SPECIES OF MONOSTROMA. i. Frond always tubular. 2. I. Frond tubular only in an earl}' stage of growth. 3. 2. Tube filiform. i. M. groenlandicum. 2. Tube intestine-like, collapsing. 4. M. arcticuin var. intestinifornie. 3. Frond saccate till plant is well developed : then splitting part or all of the way to the base. 4. 3. Frond saccate only in the early stages or not at all. 5. 4. Segments rather broad, irregularly divided. 2. M. Grevillei. 4. Segments narrowly linear, simple, forked or palmate. 3. M. Lactuca. 5. Frond dark to dull green, not adhering to paper, n. M. fiiscum. 5. Frond light or bright green, adhering generally to paper. 6. 6. Mature frond divided into distinct segments. 7. 6. Frond broadly lanceolate to orbicular, not divided into segments. 8. 2o8 TUFTS COLLEGF STUDIES, VOL. II, No. 3 7. Segments linear or lanceolate, frond about 6 /j. thick above. 5. M. pulchrum. 7. Segments few, broad ; frond 25-45 M thick ; cells close. 4. M. arcticum. 7. Segments obovate, frond 18-36 /j. thick ; cells not closely set. 7. M. crepidinum. 8. Frond not over 30 /a thick, except near the base. 9. 8. Frond 40-50 /* thick. 12. 9. Frond not usually much plicate. 10. 9. Frond usually much plicate. 13. 10. Cells arranged in distinct groups of 4. 9. M. quaternarium. 10. Cells not in distinct groups of 4. n. ii. Cells in longitudinal and transverse series. 12. M. leptodermum, ii. Cells not in series. 8. M. latissiinum. 12. Chromatophore in cross section not over 9 /j. high. 6. M. undulatum. 12. Chromatophore in cross section about 15 M high. 10. M. orbiculatuin. 13. Frond much lobed, margin distinctly thinner than base. 10. M. orbiculatuin var. ziariuin. 13. Frond not much lobed ; thickness nearly uniform. 6. M. undulatum var. Farlowii. i. M. GROENLANDICUM J. G. Agardh, 1882, p. 107, PI. Ill, figs. 80-83; P. B.-A., No. 13. Frond filiform, tubular, cylin- drical, up to 15 cm. long, from a very slender base expanding to i mm. diameter ; apex broken only at exit of spores. Cells in the lower part of the frond loosely arranged in twos and fours, roundish angular ; in the upper part more evenly distri- buted, more or less closely set. In cross section the membrane is 25-35 /"• thick ; the cells radiately elongate, 2-4 times as long as broad ; in the younger parts the central cavity is filled with a gelatinous substance, which disappears as the plant becomes older. Spores or gametes formed first at the summit of the frond, and developing successively in lower cells. Greenland to Mass.; Alaska. This plant has no external resemblance to a Monostroma, and was placed in this genus with a mark of doubt by both Farlow and Rosenvinge. It appears like a slender, unbranched Entero- morpha, but seems, however, to be in structure more nearly related to Monostroma. It occurs from April to June in New England ; in July at Newfoundland ; and from May to August in Greenland. On the Atlantic coast it grows in. rather dense tufts, at the lower limit of the literal zone, in company with THE GREEN ALGAE OF NORTH AMERICA 209 Spongomorpha arcta, Bangia fusco-purpurea, Hormiscia, etc. In all specimens from the Pacific coast that have been examined, the cells are decidedly smaller than in specimens from the Atlantic ; 8-10 p. diam. in the former, 12-16 //, diani. in the latter, seen superficially. 2. M. GREVILLEI (Thuret) Wittrock, 1866, p. 57, PI. IV, fig. 14; Farlow, 1881, p. 41 ; P. B.-A., No. 15; Ulva Lactuca Harvey, 1846-51, PI. CCXUII ; 1858, p. 60. Frond attached, at first saccate, then opening at the top, and ultimately splitting to the base ; soft and delicate, pale green ; membrane 15-20 /A thick, cells quadrate with rounded angles, closely set ; in cross section horizontally oval, 12-14 P- high. Sporiferous cells enlarged, vertically elongate in cross section ; cell wall dis- solving after emission of spores. Greenland to N. J.; Alaska to Cal. Europe. The saccate form is plain in young plants, and may persist for some time when growing in still water ; but at exposed points the frond is soon torn open, and in mature plants all trace of the original shape is lost, wherever growing. An early spring plant except in Arctic regions, where it con- tinues till August. Var. VAHUI (J. Ag.) Rosenvinge, 1893, p. 949; M. Vahlii J. G. Agardh, 1882, p. 109, PI. Ill, figs. 84-89. More slender in form, often cylindrical, retaining its saccate shape longer, and with cells arranged in more or less distinct longitudinal series. An early spring plant. Greenland to Mass.; Alaska. Var. lubricum (Kjellman) nov. comb.; M. lubricimi Kjellman, 18773, p. 48, PI. IV, figs. 8 and 9. Frond up to 15 cm. long, pale or whitish green, delicate, very lubricous and flaccid, of irregular outline, laciniate, plicate, margin often crisped and lacerate; frond 18-22 /j. thick; cells seen superficially, circular or rounded angular, often in twos or fours, cell wall thick ; in cross section horizontally ovate or oblong, 4.5-8 /x high. Green- land, Alaska. Northern Erirope. This has never been found attached, but always as shapeless floating fronds ; with our imperfect knowledge of it, it is prob- able that it is a form of M. Grevillei in which the cells are some- what shrunken, the membrane much gelatinized. 3. M. IvACTUCA (Roth) J. Ag., 1882, p. 102, PI. Ill, fig. 90 ; Areschoug, Alg. Scand. Exsicc., No. 121 ; P. B.-A., No. 1271. Frond at first an elongate, obconical sac, soon splitting to the base into linear, simple or forked laciniae, usually with 210 TUFTS COLLEGE STUDIES, VOL. II, No. 3 crisped edges ; membrane 20-25 )"• thick ; cells seen superficially parenchymatously united, chromatophore not filling the cell ; cells angular, often arranged in twos, threes or fours ; in cross section rounded, horizontally elongate, 15-18 /x high. Cell walls persisting after emission of spores. Mass., R. I., Conn. Europe, A spring plant, nearly allied to M . Grevillei, but quite dis- tinct in habit and texture. It has a thicker membrane, which is also firmer and less lubricous. M '. Grcvillci forms at first a globular or obovate sac, splitting into broad segments of indefi- nite shape ; M. Lactuca at first is a longer sac, and divides into long, sublinear laciniae, often with a tapering stipe-like base ; when these laciniae are simple, the resemblance to Enteromorpha linza is striking ; when they fork, which is often the case, the resemblance to £ r/va fasciata is equally marked ; there are some fronds with quite distinct palmate division of the laciniae. 4. M. ARCTICUM Wittrock, 1866, p. 44, PL II, fig. 8 ; P. B.-A., No. 910. Frond attached, at first saccate, soon splitting into a few broad laciniae ; subradiately plicate, with crisped margin ; pale green, becoming yellowish in drying ; membrane 25-45 /j. thick ; cells 4-6 angled, closely set, irregularly placed ; in cross section either vertically or horizontally oval, 10-30 ^ high. Greenland, Alaska. Northern Europe. A northern species, chiefly distinguished from M. Grcvillci by the thicker frond, which is saccate only in the earliest stages and afterwards appears as a rather broad membrane, not split up into strips, as is usual in M. Grcvillci. M. saccodcuui Kjell- man, 1883, p. 296, PL XXVIII, figs, i-io; M. cylindraccion Kjellrnan, 1883, p. 295, PL XXX, and M. angicava Kjellman, 1883, p. 297, PL XXIX, seem to be forms of M. arcticnm. Var. intestiniforme (Rosenv.) nov. comb. ; M. Grevillei var. intestiniforme Rosenvinge, 1893, p. 953, fig. 52. Frond tubular, to 50 cm. long ; membrane 25-50 //.thick ; cells rounded, closely set, vertically oval in cross section, 15-20^ high; usually ar- ranged in more or less distinct series longitudinally. Green- land. Resembles in habit M. Grevillei var. Vahlii, but in thickness of membrane and size and shape of cells agrees with M. arcticuin ; it is rather persistently tubular, and except by careful ex- amination of its structure, is liable to be mistaken for Entero- morpha intestinal is. THE GREEN ALGAE OP NORTH AMERICA 211 5. M. PULCHRUM Farlow, 1881, p. 41 ; P. B.-A., No. 658. Frond divided into linear or lanceolate segments with slender base, much crisped at the margin, light green, membrane about 6 /j. thick in the upper part, up to 15 /A near the base, cells roundish, rather irregular in form. A beautiful species, extremely delicate, adhering so closely to paper when mounted that it is almost impossible to detach it for examination. It occurs on rocky shores, usually epiphytic on other algae, from April to June. Newfoundland to R. I. 6. M. UNDULATUM Wittrock, 1866, p. 46, PI. Ill, fig. 9. Frond membranaceous, soft and flaccid, with strongly undulate margin ; 40-50 //. thick ; cells angular, closely set, showing somewhat of an arrangement in twos, threes, and fours ; in cross section about 20 /u, high, semicircular or oval ; chromato- phore not occupying the full height of the cell ; not over 10 ^ in the middle. Greenland. Northern Europe. The typical form has a thicker frond than any other species but M. fuscum, which is not likely to be mistaken for it, being amply distinct by its color and consistency. Var. FARivOwn Foslie, 1890, p. 114; P. B.-A., No. 406. Frond similar to the type, but less than 30 /j. thick. Greenland to Mass. Norway. 7. M. CREPIDINUM Farlow, 1881, p. 42; P. B.-A., No. 220. Frond delicate, light green, 5-15 cm. long, flabellately orbicu- late, when fully developed split nearly or quite to the base, seg- ments obovate ; membrane 18-36, rarely 45 //.thick ; cells round- ish-angular, when actively dividing forming compact groups of 2, 3, or 4, separated by rather wide spaces. Mass, to N. J. On woodwork between tide marks, also on rocks ; it is usually in rather dense tufts, which have a rich dark green color, though the individual frond is light green. It resembles in habit the European M. Wittrockii, but has a thicker frond, with cells more elongate horizontally in cross section. M. Wittrockii is more membranaceous in texture, not adhering well to paper. 8. M. LATISSIMUM (Ktitz.) Wittrock, 1866, p. 33, PI. I, fig. 4; P. B.-A., Nos. 14, 1122. Frond at first attached, afterwards floating ; thin and soft, glossy, of irregular shape, more or less plicate near the even or undulate margin ; membrane 20-25 P- thick, cells 4-6-cornered or roundish, closely set, without order or more or less distinctly in twos, threes, and fours; in cross section vertically oval or nearly circular, 14-18 // high. Me. to Fla.; Alaska to Washington. Europe, Africa, New Zealand. 212 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Apparently not uncommon in quiet waters, especially in ditches in marshes, where the water is sometimes brackish rather than salt. At first it is attached to various objects, but soon becomes loosened and floats freely, sometimes in such abundance as to quite fill a ditch from bottom to surface. It appears in spring, and continues, chiefly in the floating state, through the summer. The arrangement of cells varies in plants from the same locality, and even in different parts of the same frond ; indeed, the shape of the cells, whether seen from above or in cross section, is liable to vary in any species of Monostroma, or in different stages of growth of the individual. 9. M. OUATERNARIUM (Ku'tz.) Desmazieres, Plantes Crypt, de France, Troiseme Serie, No. 603, 1859 ; Wittrock, 1866, p. 37, PL I, fig. 5; P. B.-A., No. 567; Ulva quatcrnaria Kiitz- ing, 1856, p. 6, PI. XIII, fig. 2. Frond at first attached, soon becoming free, soft and delicate, irregularly lobed and folded, 20-23 V" thick ; cells rounded, when active!}' dividing set closely in threes and fours within the mother cell wall ; in cross section semicircular or oval, 15-17 /A high. In brackish or fresh water, Washington to Cal. ; various fresh water localities throughout the western U. S. Europe. 10. M. ORBICULATUM Thuret, 1854, P- 388; Wittrock, 1866, p. 39, PI. II, fig. 6 ; Alg. Am. Bor., No. 173. Frond mem- brauaceous, attached by fibrils, or later free ; soft and flaccid, sub-orbicular or irregular in outline, often radially plicate, with undulate margin, 30-40 ^ thick ; cells angular, varying much in size and arrangement, often irregularly elongate, closely set, but with chromatophore not occupying the whole cell ; in cross section vertically oval, 25-30 ^ high. In fresh and brackish water. Bermuda, Cal. Europe. L,ike other species, this varies much in color, the Bermuda plant being a full green, the California plant quite pale. In the Bermuda specimens the frond is somewhat thinner than the type, and the radical fibrils are strongly developed. Var. VARIUM Collins, igoga, p. 26. Frond very much lobed and plicate, forming a rosette-like expansion, attached at the center ; frond 50-60 p. thick in the older part, diminishing to 16 P at the margin. On muddy shore near low water mark. So. Mass. The much divided and very much folded frond is quite differ- ent in appearance from the typical Af. orbiculatnm, but no differ- THE GREEN ALGAE OF NORTH AMERICA 213 ence can be seen in the form and dimensions of the cells, except that the membrane is thicker in the older parts and thinner in the younger in var. varium, than in the type, in which the frond is of nearly uniform thickness. ii. M. PUSCUM (Post, and Rupr.) Wittrock, 1866, p. 53, PI. IV, fig. 13. Frond membranaceous, at first tubular, soon split- ting, dull green, more or less lobed but not divided to the base ; membrane 20-35 /* thick ; cells 4-6-angled, very closely set; in cross section quadrate, with only slightly rounded corners ; occupying nearly the entire thickness of the frond. Greenland, Alaska. Northern Europe. Under this species are included two forms, which, with the type, pass into each other with 110 dividing line, while they are sharply marked off from all other species of the genus in nearly eveiy respect. The very young plant is in the form of a closed tube, which soon splits down one side, and spreads out to form a flat membrane ; not splitting into several segments, as in the Grevillei group. Compared with other species of Monostroma, the fit sen in forms are thick and coarse, blackish when dried, staining the paper on which they are mounted, and not adher- ing well to it. Forma BLYTTII (Wittr.) Collins, 1903, p. 12 ; M. /?#'//// Witt- rock, 1866, p. 49, PI. Ill, fig. ii ; Farlow, 1881, p. 41 ; M.fus- cum, P. B.-A., No. 715. Frond deep green, blackish in drying, 60-70 /u, thick ; cells " palisade-form " in cross section. Fig. 72. Greenland to R. I. ; Vancouver Island, Washington. A plant of late autumn and winter in New England, in tide pools and also on pebbles in the sublitoral zone ; great quanti- ties are sometimes washed ashore by storms, the stones on which they grew remaining attached to them. Forma SPLENDENS (Wittr.) Collins, 1903, p. 12; P. B.-A., No. 911 ; M. splendcns Wittrock, 1866, p. 50, PI. Ill, fig. 12. Frond deep green, glossy, 50-55 p. thick, more deeply parted than in the other forms ; cells similar to those of forma Blyttii, or more rounded. Alaska to Vancouver I. Northern Asia. 12. M. LEPTODERMUM Kjellman, 1877, p. 52,- PI. I, figs. 23 and 24; P. B.-A., No. 1272; M. zostericohnn Tilden, Amer. Algae, No. 388. Frond cuneate-obovate or divided into segments of that form ; cells squarish, in distinct series, longitudinal and transveVse ; the former often radiate, the latter concentric ; mar- 214 TUFTS COLLEGE STUDIES, VOL. II, No. 3 gin more or less undulate ; membrane 7-10 p. thick, cells quad- rate in cross section, 5-8 p. high. Greenland (?), Mass., Wash. Arctic Sea. This species has the most delicate frond of all the genus, except M.pulchrum, and grows in spring below low water mark or in pools. It was founded by Kjellmau on specimens found unattached, without basal part ; Rosenvinge, 1893, p. 944, identifies with it a plant from Greenland, with a filiform, tubu- lar stipe of varying length. No such stipe has been seen in the specimens from Massachusetts and Washington ; hundreds of specimens of all stages of growth have been examined, without finding any indications of a stipe. The structure of our plant agrees with Kjellman's description and figures, and his name is here retained ; it may be that the Greenland plant is distinct from that of northern Europe.* • 4. ULVA Linnaeus, 1753, p. 1163. Frond membranaceous, flat, consisting of two layers of cells, in any of which, except those in the thickened base, zoospores or gametes may be formed, issuing through an opening in the surface of the frond. Marine. KEY TO THE SPECIES OF ULVA. i. Frond divided into distinct segments. 3. U.fasciata. i. Frond entire or irregularly lobed or laciniate. 2. 2. Frond minute, triangular or reniforrn, with distinct stipe. 2. U. calif or nica. 2. Frond ample, at first lanceolate, later of no definite outline. i. U. Lactuca. i. U. LACTUCA Linnaeus, 1753, p. 1^163; Thuret and Bor- net, 1878, p. 5, Pis. II, III ; U. Lactuca var. Lactuca Farlow, 1 88 1, p. 43. Frond very variable in shape, at first attached and generally of a lanceolate or ovate-lanceolate form ; later of irreg- ular shape, and often detached and floating. The cells usually vertically elongate in cross section ; seen from the surface irregularly angular, closely set ; thickness of the frond very variable. Fig. 75. "There have been several reports of M. thermalis fro,m interior points of the United States, and in some cases the determination was confirmed by J. G. Agardh. But the latter, 1882, p. no, expresses considerable doubt as to whether what he understands as M. thermalis, is the same as the Ulva thermalis of Meneghiui, 1837, p. 21. All the American speci- examined, including several in Herb. Farlow, prove to be species of Enteromorpha. THE GREEN ALGAE OF NORTH AMERICA 215 A very common plant over the whole world, and extremely variable in form, thickness and color. Two fairly marked types can be distinguished in the species as found with us on both Atlantic and Pacific coasts, connected by innumerable forms. Var. RIGIDA (Ag.) Le Jolis, 1863, p. 38; Farlow, 1881, p. 42 ; P. B.-A., No. 407. Frond at first lanceolate or ovate- lanceolate, firm and stiff, with a distinct stipe ; later somewhat irregularly divided, and often with numerous perforations of various sizes ; cells vertically elongate in cross section. This is a common form of exposed shores, but occurs also sometimes in quieter waters. In its earlier stages it is dis- tinctly lanceolate in outline, but this form is afterwards lost by irregular growth. It is firm in texture, the color deepening as the plant grows older, finally becoming brownish or blackish ; the cells have their greatest length at right angles to the surface of the frond, being sometimes three times as long as wide. Var. LATISSIMA (L.) DC., 1805, p. 9 ; P. B.-A., No. LXXVI. Frond irregular in outline, soon becoming detached and passing most of its life in a floating condition ; thinner than var. rigida, lighter colored, and with cells nearer square in cross section. This is a common form of creeks and lagoons, where it forms floating sheets, often of several square meters in extent. Var. MESENTERIFORMIS (Roth) Collins, 1900, p. 45. Frond much contorted and bullate, forming crumpled masses, lying loose on the bottom. This form is strikingly distinct in appearance, forming much crisped and wrinkled masses, usually of a dark green color, lying on the bottom in creeks and quiet bays. It is so twisted and grown together that only by tearing can even a small piece of it be spread out flat. In cross section the cells are nearer square than those of the type. It is common in marshy pools near Bridgeport, Conn., and will probably be found in similar places. Known elsewhere only in the Baltic. 2. U. CALIFORNICA Wille, P. B.-A., No. 611. Frond 1.5 to 2 cm. long, up to 1.5 cm. wide, triangular or reniform with wavy edge, sometimes with proliferations of a few cells each ; passing quickly into a flattened, tapering stipe. The cells of the stipe, which on the inner side form rhizoidal prolongations, are in cross section about quadrate ; the cells in the upper part 216 TUFTS COLLEGE STUDIES, VOL. II, No. 3 of the frond are rather irregularly polygonal with rounded cor- ners ; no noticeable arrangement in longitudinal series ; frond about 30 n thick. A species with minute fronds, with more definite outline than is usual in species of this genus. It is known only from Cali- fornia, where it forms a rather dense coating on rocks near high water mark. Hardly enough is known of this plant to decide whether its position is permanently assured. 3. U. FASCIATA Delile, 1813, p. 153, PI. LVIII, fig. 5; Harvey, 1858, p. 58; P. B.-A., No. 221. Frond divided into more or less linear segments, margin smooth or undulate ; in cross section the two layers of cells separate somewhat at the margin, which is rounded, with a small, open space between the rows. Fla., W. I., Cal. Warm waters all over the world. The structure of the frond is similar to that of U. Lactuca, ex- cept the margin, which resembles Enteromorpha linza ; but the shape of the frond, with definite divisions, is quite distinct in the typical form. On the Californian coast, however, it is hard to draw the line between this and U. Lactuca, either from the shape of the frond or from its structure. Even in the typical form there is much diversity as to the divisions of the frond ; they may be dichotomous or apparently lateral ; their width may vary from 5 mm. to 5 cm. ; and the frond may reach a length of a meter ; the margin may be smooth and even, or much crisped and undulate ; in this last it corresponds to forms of Enteromorpha linza. Four forms have been distinguished on the Pacific coast, passing into each other more or less. Forma TAENIATA Setchell, P. B.-A., No. 862. Lobes slen- der and elongated, crisped and ruffled ; prominent teeth on the margins near the base of the frond. Forma CAESPITOSA Setchell, P. B.-A., No. 809. Divisions numerous, irregular ; fronds intricately entangled, forming a dense coating on the rocks. Forma LOBATA Setchell, P. B.-A., No. 863. Lobes short and broad, seldom crisped or ruffled. Forma EXPANSA Setchell, P. B.-A., No. L,XXVII. Frond ample, of generally orbicular outline, lobes broad or narrow, more or less sinuous, margin much ruffled ; frond 60-70^ thick, cells somewhat elongate in cross section. THE GREEN ALGAE OF NORTH AMERICA 217 PROTODERMA Kiitzing, 1843, p. 295. Frond a minute disk, closely attached to the substratum, formed originally of radiating, branching filaments, which, ex- cept at the margin, are united to a sub-parenchymatous layer of one or more cells in thickness ; cells with parietal disk-shaped chromatophore and one pyrenoid ; asexual reproduction by aplanospores and by biciliate zoospores with red stigma. The proper position of this genus is quite uncertain ; West, 1904, places it in the Pleurococcaceae ; Oltmans, 1904, ignores it ; it must be placed somewhere, and in the Ulvaceae is as good a place as any. There is no doubt that immature organ- isms of many kinds have passed under the name of P. viride, but P. marinum is more distinct. KEY TO THE; SPECIES OF PROTODERMA. i. Fresh water. i. P. viride. i. Marine. 2. P. marinum. ^ i. P. VIRIDE Kiitzing, 1843, p. 295 ; 1856, p. 6, PI. XI, fig. i. Frond pale green, at first circular, later more or less irregular; filaments parenchymatously united in the interior of the disk, free at the margin ; cells in the young frond with thin wall, cylindric to cuneate, 3-6 p. wide, usually 2-3 times as long ; in middle of adult frond 6-8, or even 12 /x. wide, 1-2 times as long, spherical, ovoid, or ellipsoid, with thick wall ; zoospores globose to ovoid, 3-3.5 p diam. ; aplanospores globose to ellip- soid, 2-3 fj. diam. Fig. 73. On wood and stones in ponds. Mass., Barbados. Europe. ' 2. P. MARINUM Reinke, 1889, p. Si ; P. B.-A., No. LJII. Forming thin coatings of irregular form, composed of angular, parenchymatously united cells, 6-12 p. wide, irregularly placed, except at the margin, there in rather indistinct radiating series. Me. to Conn. Europe. Common as a thin green film on pebbles in pools and at low water mark, along the New England coast ; probably elsewhere. Family 3. PRASIOLACEAE. Filamentous or membranaceous ; cells with star-shape chro- matophore and one pyrenoid ; asexual reproduction by segment- ation of the frond, by akinetes and by aplanospores; sexual reproduction unknown. Fresh water or marine. KEY TO THE GENERA OF PRASIOLACEAE. i. Frond normally of a single series of cells, occasionally expanding laterally to two or a few series. i. SCHIZOGONIUM. 2i8 TUFTS COLLEGE STUDIES, VOL. II, No. 3 i. Frond at first of a single series of cells, soon becoming a membrane. 2. PRASIOLA. i. Frond at first of a single series of cells, soon becoming a terete multi- cellular filament. 3. i. SCHIZOGONIUM Kiitzing, 1843, p. 245. Frond normally a filament of a single series of cells, but at times dividing longitudinally, so as to form ribbon-shaped fronds, two or a few cells wide ; cells usually shorter than their diameter, with central stellate chromatophore and one pyrenoid ; asexual reproduction by akinetes and aplanospores. Usually terrestrial algae, normally filamentous, occasionally dividing longitudinally, but not forming distinctly foliaceous expansions. Gay, 1891, gives a broader extension to the genus, adding 6". cri spurn, which appears here as Prasiola crispa. This species produces filamentous fronds which may or may not develope into membranes ; it connects the two genera, and it is not easy to decide under which to include it. KEY TO THE SPECIES OF SCHIZOGONIUM. i. Uniseriate filaments cylindrical ; multiseriate not uncommon. i. S. tmirale. i. Uniseriate filaments moniliform or crenulate ; longitudinal cell- division in a single cell or in a few successive cells. 2. S. crenulafiiui . 1. S. MURALE Kiitzing, 1843, p. 246; Gay, 1891, p. 87, PI. XIII, figs. 122-125. Forming a soft, tomentose stratum, bright or dull green ; filaments flexuous, simple or rarely with short, few-celled branches; cells usually 10-14 /A diam., occasionally a little more or less ; often biseriate ; rarely pluri-seriate. On moist earth, rocks, trees, etc. N. H., Alaska. Europe. Var. ALPINUM Farlow, P. B.-A., No. 70. Submerged; forming long, loose, floating tufts in mountain brooks. N. H. 2. S. CRENULATUM (Kiitz.) Gay, 1888, p. 72 ; 1891, p. 88, PI. XIII, fig. 131. Forming a thin stratum, bright or dull green ; filaments more or less moniliform or crenulate, rather stiff, entangled, 11-14 f- diam., occasionally one or a few cells duplicated ; cells about as long as broad, more or less swollen at the middle, walls between the cells quite thick. Fig. 76. On moist wood, etc. N. H., Mass. Europe. 2. PRASIOLA (Ag.) Meneghini, 1838, p. 36. Fronds membranaceous, monostromatic, attached by short fili- form prolongations, by the edge of the membrane, or by a thick- THE GREEN ALGAE OF NORTH AMERICA 219 ened stipe ; cells with stellate chromatophore and one pyrenoid, dividing to form groups of fours, these groups forming similar larger groups, the spaces between the groups of various orders constituting narrower or wider spaces, running in definite direc- tions through the frond. Asexual reproduction, ist, by the breaking off of small portions of the frond, which attach them- selves and grow independently ; 2d, by akinetes formed from individual cells assuming thick walls : these akinetes may develop either directly into a filament or membrane, or indi- rectly by aplanospores, several in each akinete ; 3d, by aplano- spores, formed 4-8 in a cell, by walls in 2 or 3 directions ; sexual reproduction unknown. The species of this genus resemble small forms of Ulva or Monostroma ; most of them are so minute as to be barely notice- able, but some may reach a length of 10 cm. Some species grow in cold mountain streams, but most of them are found in moist places, not immersed ; some inhabit by preference quite uncleanly stations ; a few species are marine. While there have been reports of the production of zoospores, it is now gen- erally supposed that these reports were based on misapprehen- sions, and that the reproduction is asexual and non-motile. In the character of the frond, and in the formation of spores, there are quite interesting similiarities between Prasiola and Porphyra. KEY TO THE SPECIES OF PRASIOLA. i. Marine. 4- P- borealis. i. Fresh water or terrestrial. 2. 2. Frond with long, stipe-like base. 3. 2. Stipe short or wanting. 4. 3. Frond near base of a single series of cells. i. P. calophylla. 3. Frond always of several series of cells. 2. P.fluviatilis. 4. Terrestrial. 5. P. crispa. 4. In cold mountain streams. 3. P. mexicana. i. P. CALOPHYLLA (Spreiig.) Meneghini, 1838, p. 36; Jes- sen, 1848, p. 14, PI. I, figs. 1-3; P. B.-A., No. 1273. Fronds linear to narrowly cuneate, with truncate apex, many from the same holdfast, seldom over i cm. long, i mm. wide ; cells near the base in a single series, about 10 ^ long by 3-5 ^ broad ; farther up in two rows, the number increasing towards the upper part of the frond or as the frond grows older ; the series of cells and the intercellular lines nearly parallel throughout ; cells near the apex of the frond about 3-5 ^ square ; thickness of frond about 15 /A; cells S-io /j. high in cross section. Wash., Cal. Europe. 220 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The minute linear fronds with filiform stipe and truncate apex, distinguish this species from others of the genus. 2. P. FLUVIATILIS (Sommerf.) Areschoug in Lagerstedt, 1869, p. 28; Wittr. and Nordst., Alg. Exsicc., No. 1234; P. Sauteri, Jessen, 1848, p. 15, PI. I, figs. 4-9. Fronds cuneate- lanceolate to obovate, to 10 cm. high, 2 cm. wide, apex obtuse, not truncate ; cells near the base in a few series, above more numerous ; series of cells and intercellular spaces parallel be- low, more areolate in the upper part ; cells 4-6 /j. wide ; frond 13-19 /A thick, cells 8-13 /x in cross section. Greenland, Alaska. Europe. A plant of cold mountain streams, iti general shape some\vhat like P. calophylla, but larger, with rounded apex, and without monosiphonous stipe except at very early stages. 3. P. MEXICANA J. G. Agardh, 1847, p. 6 ; Jessen, 1848, p. 19, PI. I, figs. 17-20 ; P. B.-A., No. 1186. Frond up to 10 cm. long and wide, of more or less rounded outline, attached by a short, thickened stipe; cells 6-16 /* diam., rather closely set ; asexual reproduction by division of frond, by akinetes more rounded than the vegetative cells, and with slightly thicker wall ; and by aplanospores formed 8-16 in a cell, in the upper marginal portion of the frond, from subglobose to oblong, 6-8 ^ wide, up to 14 /u. long. In cold mountain streams, sometimes at very high altitudes. Wyo., Oregon, Colo., Mexico. So. America. In appearance quite like a small Ulva ; the areolate character is not so conspicuous as in some other species ; at the formation of the aplanospores the margin for a greater or less depth be- comes softer and of lighter color, very much in the same way as on the formation of the antheridia in Porphyra. 4. P. BOREALIS Reed. 1902, p. 160, PI. XV. Fronds cune- ate to obovate, stipitate or sessile, margin crenulate, crisped or entire, soft membranaceous, 33-45 p- thick, 5-10 mm. high, in tufts of several from one holdfast ; cells in distinct tetrads, areo- lar arrangement manifest ; cells 4-9 p. diam., seen superficially ; in cross section oblong or palisade-form, 11-14 P- high- On rocks near high water mark. Alaska. The fronds of this species are very generally infested with a fungus, Guignardia Alaskana Reed ; it has its counterpart in antarctic regions in Prasiola tesselata Kiitz., infested by G^lig- nardia Prasiolae (Winter) Reed. 5. P. CRISPA (Lightf.) Meneghini, 1838, p. 36; Jessen, THE GREEN AI.GAE OP NORTH AMERICA 221 1848, p. 18, PI. I, figs. 10-16; Wolle, 1887, p. 106, PI. XCI, figs. 25-27; P. B.-A., Nos. 1069, 1184. Frond of indefinite form, rounded, lacerate, or plicate, without stipe, attached to substratum by the edge of the frond or by fine fibrils ; usually in dense masses ; fronds sometimes as much as 10 cm. high or wide, but usually much smaller ; generally 13-16 p. thick ; cells squarish or rectangular, 8-13 //, diam., in cross section square or slightly higher than wide. Fig. 77. In moist and especially in unclean places. Greenland, Newfoundland, Alaska, Cal. Europe. The description given above is of the normal adult frond ; along with this are generally found very narrow forms, only two or three cells wide, and also forms of a single series of cells ; the latter agreeing in every way with what has been known as Hormidium parietinum or H. imcrale ; these have been distri- buted as P. B.-A., Nos. 969, 1274; but every gradation can be found between these and the typical Prasiola fronds, and there is little doubt that under certain conditions or in certain stages the Prasiola develops the Harmidium forms. The areolate structure is not so clear in P. crispa as in some other species, but it shows distinctly enough in the younger plants, becoming less distinct as the plant grows older.* 3. GAYELLA Rosenvinge, 1893, p. 936. Frond filiform, simple or very slightly branched, at first of a single series of cells, later dividing longitudinally into many series, but always remaining filiform, not flat ; cell structure as in Prasiola. Marine. G. POLYRHIZA Rosenvinge, 1893, p. 937, figs. 45 and 46; P. B.-A., No. 914. Frond at first a simple filament of a single series of disk-shaped cells, 10-12 ^ diam., attached to the sub- stratum by a rhizoidal projection from the lower cell ; later attached at various parts of the filament by rhizoidal growths, one or two from a cell ; increasing in diameter by growth and division of cells, up to 70 //. diam.; terete or somewhat irregular in surface, but not flattened ; cells with parietal chromatophore and one pyrenoid ; in the mature plant showing superficially an arrangement in longitudinal and transverse lines ; in cross sec- tion an arrangement by 2-4-8-16, etc., in somewhat Gloeocapsa- like form ; asexual reproduction by aplanospores, arranged in * P. Gardneri Collins, P. B.-A., No. 1185, there placed with some doubt in this genus, seems on further study to belong rather to the blue-green algae. 222 TUFTS COLLEGE STUDIES, VOL. II, No. 3 longitudinal and horizontal series. Figs. 78, 79. Greenland, Alaska. Borgesen, 1902, p. 482, includes Gayella in Prasiola crispa as subspecies manna. It is certainly hard to draw the line be- tween Prasiola, Schizogonium and Gayella ; but the habit of Gay- ella is so distinct from the other two genera, that until we have definite evidence of the connection, it would seem better to maintain the genus. Family 4. CYLINDROCAPSACEAE. Frond a monosiphonous, rarely partly polysiphonous filament, at first attached, later free, composed of cells with parietal chro- matophore and one pyrenoid ; asexual reproduction by zoospores has been reported, but is not fully confirmed ; akinetes as in Ulothrix ; sexual reproduction by antheridia and oogonia, 2-4 antheridia formed by division of a vegetative cell, each anther- idium producing 2 spindle-shaped, biciliate, yellowish spermato- zoids, escaping through an opening in the side wall ; oogonium formed from a swollen vegetative cell, containing one oospore, fertilized by spermatozoids entering by an opening in the wall ; fertilized oospore reddish, development unknown ; the unferti- lized oospore may develop parthenogenetically, remaining green, and dividing to form a new filament. Fresh water. Only one genus. CYLINDROCAPSA Reinsch, 1867, p. 66. Characters of the family. In its vegetative characters Cylindrocapsa is nearly related to Ulothrix, but in fructification it shows considerable resemblance, and is the only alga having any considerable resemblance, to the Oedogoniaceae. C. GEMINELLA Wolle, 1887, p. 104, PI. XCI, figs. 1-17 ; P. B.-A., No. 570. Filaments 14-16 /u. diam. (or more ?) subtoru- lose, with thick, distinctly lamellate wall ; oospore globose, about 50 /a diam., lamellate wall about 10-15 p. thick. In stand- ing water, free or adhering to other algae. Fig. 80. Mass. ; " N. Y. to Florida and westward," Wolle.* Eiirope. Family 5. OEDOGONIACEAE. Fronds aquatic, in one European species terrestrial, consisting *C. amoena Wolle, 1887, p. 105, PI. XCI, figs. 18-23, with filaments cyl- indrical, 7-12 fj. diam., cells 2-3 diam. long, fructification by zoospores of two sizes, can hardly be recognized from the description ; there is really nothing to indicate that it is a Cylindrocapsa. THE GREEN ALGAE OF NORTH AMERICA 223 of simple or branching filaments, of a single series of uninucle- ate cells ; chromatophores generally of many longitudinal bands, with many pyrenoids ; cell division by the rupture of a circular ring, which forms the membrane of the new cell. Asexual re- production by multiciliate zoospores, each produced from the entire contents of a cell, and germinating immediately ; also in some cases by akinetes. Sexual reproduction by oogonia and antheridia ; oogonia single or seriate, formed by transformation of vegetative cells ; opening by a lid or a pore to admit the spermatozoids ; when fertilized the oospore assumes a mem- brane ; after a period of rest the oospore produces four zoospores (occasionally fewer or more), which germinate at once. Anther- idia either in the same filament with the oogonia or in separate individuals ; male plants either of about the same sized cells as the female plants, or much smaller ; in the latter case the male plants arise from androspores, similar to zoospores but smaller ; spermatozoids produced one or two in an antheridium, smaller than the androspores, but of similar appearance. Fresh water. The Oedogoniaceae are distinct from all other families, only the very small family of the Cylindrocapsaceae showing any near relationship. There are two genera of world- wide dis- tribution, Oedogonium and Bulbochaete ; Oedocladium, a mono- typic genus, is found in Europe. The vegetative structure is of the simplest, but the mode of cell division is found nowhere else ; the reproductive characters are elaborate and varied, and the special variations peculiar to the different species seem to be quite constant. A very thor- ough study of the family has been made by Hirn, and his mono- graph is the basis for the following pages ; his descriptions have been closely followed, few changes or additions being required for present purposes. i. OEDOGONIUM Link, 1820, p. 5. Frond of a single, unbranched series of cells, vegetative cells cylindrical, rarely with constrictions; basal cell with holdfast ; terminal cell obtuse, apiculate or produced into a lon^ seta ; all cells capable of division ; oogonia produced dirt-ctly by division of a vegetative cell. In this genus there are more definite characters for distinc- tion of species than in any other of the larger genera of grei ' algae, and these characters are qu'te constant in each specie> ; abnormal developments are of course to be expected, but tiny 224 TUFTS COLLEGE STUDIES, VOL. II, No. 3 can usually be recognized as such. The chief difficulty lies in the fact that different organs may be distributed over two or three distinct classes of filaments, and it is by no means easy to get all in the same collecting. Add to this the fact that differ- ent species frequently grow together, so that it is rather the ex- ception to make a collection all of one species, and it will be seen that it is only too easy to overlook one of the forms of the species under consideration, or to mistake for it a filament of another species. The peculiarities of the species of Oedogonium require a num- ber of special names to be used in the descriptions, and they may be summarized as follows : the antheridia and oogonia may occur on the same filament (monoecious species)or on separate fila- ments (dioecious) ; in the latter case the male filaments may be nearly similar to the female (macrandrous species) or very much smaller (nannandrous). In the latter case the male filaments (nannandres, dwarf males) are minute plants of a few cells each, epiphytic on the female filament, usually on the oogonium or on the cell below it (suffultory cell). These dwarf males are produced by the germination of special spores (androspores) produced in androsporangia ; the androsporangia are short cells, usually narrower than the vegetative cells of the filaments in which they occur ; they are either single or two or more in a series ; they occur in the same filament as the oogonia (gynan- drosporous species) or in separate filaments (idioandrosporous) ; when the former they may be directly above the oogonium (epigy- nous) or a short distance above the oogonium (subepigynous), di- rectly below the oogonium (hypogynous), or a short distance below (subhypogynous). When occurring without any reference to the oogonium they are said to be scattered. The dwarf males may be unicellular, the spermatozoids being produced in the single cell, or pluricellular ; in the latter case the antheridium may be produced merely by a partition forming in the originally unicellular male (antheridium interior) ; or in a cell or in the upper of two or more cells formed at the summit of the male by the typical Oedogonium cell division (antheridium exterior) ; in this case the^part below the antheridium is known as the stipe, and may^be one to several celled. An antheridium may pro- THE GREEN ALGAE OF NORTH AMERICA 225 cluce one or two spermatozoids ; in the latter case the sper- matozoids may be formed side by side, with a vertical par- tition (division vertical), or one above the other (division horizontal). The oogonium receives the spermatozoid either by a round opening in the wall (poriferous oogonium), or by the upper part of the oogonium separating from the lower part by a circular division all around the wall (operculate). The pore may be opposite the middle of the spore (pore median), higher up (pore superior), or lower down (pore inferior). In the operculate species the same distinction is indicated by division median, superior or inferior. The membrane of the oospore may consist of one to three layers ; in the latter case these are known as the outer membrane or exospore, median membrane or mesospore, and inner membrane or endospore. In the monoecious species the antheridia occupy positions similar to those of the androsporangia in the nannandrous gynandro- sporous species, and are similarly known as epigynous, etc. The formation of the spermatozoids is the same as in the nan- nandrous species. The subdivision of the genus is largely artificial ; the usual division is into monoecious, dioecious macrandrous, and dioe- cious nannandrous species ; but interesting parallelisms may be found between the first and third of these series. There seem to be more species of limited distribution in this genus than in most genera of green algae, but it may be due to imperfect knowledge ; certainly some species occur at widely distant sta- tions. Undoubtedly many species not yet recorded for North America will be found here when more attention is paid to them. They are all species of quiet or slowly flowing water, and may be found at any time, except when the water is frozen over. KEY TO THE SPECIES OF OEDOGONIUM. i. Macrandrous. 2. I. Nannandrous. 45. 2. Oogonium opening by a pore. 3. 2. Oogonium opening by a lid. 33. 3. Spores globose. 4. 3. Spores ellipsoid. 17. 4. Pore median. . 5. 4. Pore supramedian. 7. 4. Pore superior. n._ 226 TUFTS COLLEGE STUDIES, VOL. II, No. 3 5. Membrane of oospore smooth. 5. Membrane of oospore pitted. 5. Membrane of oospore spinous. 6. Monoecious. 6. Dioecious. 7. Pore slightly above the middle. 7. Pore almost superior. 8. Monoecious. 8. Dioecious. 9. Oogonia subglobose or subdepressed-globose. 9. Oogonia subglobose or subellipsoid-globose. 10. Monoecious. 10. Dioecious. 8. ii. Oogonia manifestly swollen, ii. Oogonia little if any swollen. 12. Membrane of oospore smooth. 12. Membrane of oospore pitted. 13. Monoecious. 13. Dioecious. 12 14. Vegetative cells 12-17 /j. diam. 14. Vegetative cells 20-30 /u diam. 15. Monoecious. 15. Dioecious. 16. Oogonia '3 to y2 wider than vegetative cells. 15- 16. Oogouia scarcely wider than vegetative cells. 3. Oe. Magnusii. 4. Oe. suecicmii. \. Oe. cryptoporuui. 2. Oe. rufesccns. 8. 10. 9- 7. Oe. cardiacum. 5. Oe. obsoletnni. >. Oe. plitsiospormn. 9. Oe. varians. Oe. franklin ia n uin. 12. 15- 13- 13. Oe.foveolatiim. 14. Oe. plagioslomutn. 10. Oe. fragile. n. Oe. Vancherii. 14. Oe. genicnlatitm. 16. Oe. cap ill I forme. 16. Oe. capillare. 18. 27- 19. 21. 20. Oe. rivulare. 18. 19. 17. Oe. npsaliense. Oe. Richterianum. 17. Oogonia manifestly swollen. 17. Oogonia little if any swollen. 18. Membrane of oospore smooth. 18. Membrane of oospore ribbed or pitted. 19. Monoecious. 19. Dioecious. 20. Division of antheridial cell vertical. 20. Division of antheridial cell horizontal. 21. Membrane of oospore ribbed. 21. Membrane of oospore areolate or pitted. 22. Ribs continuous and entire. 22. Ribs not continuous and entire. 23. Monoecious. 23. Dioecious. 24. Ribs composed of elongate dots. 24. Ribs distinctly dentate. 25. Membrane of oospore areolate. 23. Oe. crenulato-costatuin far. aitrcnni. 25. Membrane of oospore pitted. 26. 22. 25- 23- 24. Oe. paiudosum. 21. Oe. Boscii. 22. Oe. margaritiferum. 23. Oe. crenu la fo-costa finn. 20. THE GREEN ALGAE OF NORTH AMERICA 227 26. Oogonia 38-48 M diam. 25. Oe. punctatum. 26. Oogonia 70-83 //• diam. 24. Oe. taphrosporum. 27. Membrane of oospore smooth. 28. 27. Membrane of oospore pitted. 70. Oe. giganteuin. 28. Monoecious. 26. Cte. martinicense. 28. Dioecious. 29. 29. Oogonia 63-75 /j. diam. 27. Oe. Landsboroughii. 29. Oogouia 65 fj. diam. or less. 30. 30. Vegetative cells 3-9 diam. long. 31. 30. Vegetative cells i %-3 diam. long. 31. Oe. mexicanuin. 31. Oogonia oboviform. 28. Oe. oboviforme. 31. Oogonia suboboviform to oboviform-ellipsoid. 32. 32. Male plants stouter than female. 29. Oe. pachyandrium. 32. Male plants more slender than female. 30. Oe. grande. 33. Oospores globose. 34. 33. Oospores ellipsoid. 42. 34. Division of oogoniuui median. 35. 34. Division of oogonium superior. 36. 35. Cells with spiral markings. 32. Oe. punctato-striatuin. 35. Cells with walls plain. 33. Oe. Howardii. 36. Monoecious. 37. 36. Dioecious. 38. Oe. Pringsheiinii. 37. Vegetative cells with three nodulose swellings. 41. Oe. nodulosum. 37. Vegetative cells cylindrical. 38. 38. Oogonium when mature pyriform or subpyriforrn. 39. 38. Oogonium when mature oboviform-globose to subglobose. 40. 39. Oogonium 26-30 M diam. 34. Oe. Pithophorae. 39. Oogonium 40-45 ^ diam. 71. Oe. pyriforme. 40. Oogonia distinctly swollen. 41. 40. Oogonia little swollen. 37. Oe. autumnale. 41. Vegetative cells 15 ^ diam. or less. 35. Oe. crispuin. 4T. Vegetative cells 16 p. diam. or more. 36. Oe. obesum. 42. Membrane of oospore smooth. 43. 42. Membrane of oospore ribbed. 42. Oe. nobile. 43. Oogonia oblong-ellipsoid or ellipsoid. 44. 43. Oogonia pyriform. 72. Oe. sanctae thomae. 44. Vegetative cells 3-7 ju diam. 40. Oe. gracillimum. 44. Vegetative cells 10-18 M diam. 39. Oe. Ahlstrandii. 45. Dwarf males pluricellular. 46. 45. Dwarf males unicellular. 66. 46. Antheridium exterior. 47. 46. Antheridium interior. 64. 47. Oogonium opening by a pore. 48. 47. Oogonium opening by a lid. 62. 228 TUFTS COLLEGE STUDIES, Voiv. II, No. 3 48 48 49. 49. 49. 50 50 51. 51. 52. 52. 53. 53. 54. 54. 55. 55. 56. 56. 57. 57. 58. 58. 59. 59. 60. 60 60. 61. 61. 62. 62. 63. 63. 64. 64. 65. 65. 66. 66. 67. 67. 68. 68. , Oospore globose. Oospore ellipsoid. Pore median or slightly above. Pore superior. Pore inferior. Membrane of oospore smooth. Membrane of oospore spinous. Oogonium 30-37"^ diam. Oogonium 49-53 M diam. Oogonium subdepressed-globose. Oogonium subglobose to ellipsoid. 46. Membrane of oospore smooth. Membrane of oospore spinous. Oogonia solitary. Oogonia usually seriate. 59 Spines without order. Spines arranged spirally. Spines scanty ; oogonia subglobose. Spines dense ; oogonia depressed-globose. 49. diam. ; veg. cells 15-35 M diam. 50 diam. ; veg. cells 32-59 /u diam. Oogonium 51-64 Oogouium 63-78 49- 58. 50. S3- 52. Oe. Hunt ii. Si- 52. 43. Oe. Braunii. 44. Oe. flavescens. 45. Oe. putt gens. Oe. echinospcnnuni. 54- 55- 47. Oe. irregulare. Oe. nniltisporii in. 56. 57- 48. Oe. armigeniiii. Oe. echinatnin. Oe. stellatuiH. Pore median or slightly higher. Pore superior. Membrane of oospore smooth. Membrane of oospore spinous. Membrane of oospore smooth. Membrane of oospore ribbed. Membrane of oospore pitted. Suffultory cell not swollen. Suffultory cell swollen. Oospore globose. Oospore ellipsoid. Oogonia 14-23 /u diam. Oogonia 30-56 /u diam. Oogonium opening by a pore. Oogouium opening by a lid. Membrane of oospore smooth. Membrane of oospore ribbed. Oospore globose. Oospore ellipsoid. Division of oogonium medium. Division of oogonium inferior. 53- 57- 58. 60. Oospore nearly or quite filling the oogonium. Ooospore not nearly filling the oogonium. 67. i. Oe. Donne I Hi. 59- 60. Oe. sexangulare. 54. Oe. Hystrix. 61. Oe. Wolleanuin. Oe. concatenatnui. 55. Oe. crassiusculum. 56. Oe. Borisiamini. Oe. macrandriuui. 63- 61. Oe. longatuin. 62. Oe. acrospornni. 65- 64. Oe. undulatiiin. 73. Oe. cataract u »t. 63. Oe. cyathigerum. 67. 69. Oe. pluviale. 68. Oe. platygynum. 69. Oe. Areschougii. 68. THE GREEN AI,GAE OF NORTH AMERICA 229 69. Oogonium 20-27 <"• diam. 65. Oe. Rothii. 69. Oogonium 30-38 M diam. 70. 70. Oospore depressed. 66. Oe. decipiens. 70. Oospore globose. 74. Oe. londinense. MACRANDRIA, PORIFERA, GLOBOSPORA. 1. OE. CRYPTOPORUM var. VULGARE Wittrock, 1874, p. 7; Him, 1900, p. 73, PI. I, fig. 2 ; Wolle, 1887, p. 70, PI. LXXIV, figs. 1-2; P. B.-A., No. 1525. Monoecious; oogonia single or more usually 2-5 seriate, oboviform-globose or depressed-glo- bose, opening by a median pore ; oospore depressed-globose, nearly filling the oogonium ; membrane smooth ; antheridia 1-4 celled, subepigynous, hypogynous or scattered ; spermato- zoid single. veg. cell, 5-8 M diam., 3-6 diam. long. oogonia, 18-23 /x " 18-26 ti long. oospores, 16-23 /* " I5-I9 M " anth. cell, 5-7 /u " 9-12 M " Mass., Pa., N. J., sec. Wolle. Europe, Australia. The type, with somewhat larger measurements in every direc- tion, oogonia single, antheridia 1-7 celled, occurs in northern Europe, but has not been found here. 2. OE. RUFESCENS Wittrock, 1870, p. 134; Wolle, 1887, p. 89, PI. L,XXXI, figs. 16 and 17 ; Him, 1900, p. 76, PI. I, fig. 4 ; P. B.-A., No. 521. Monoecious; oogonia single or 2-3, obovi- form- or depressed-oboviform-globose, pore median ; oospore globose or depressed-globose, filling the oogonium or nearly so, membrane smooth ; male plants slightly more slender than the female ; antheridia up to i2-celled ; spermatozoid single. veg. cell, female, S-iOitdiam., 4-7 diam. long. veg. cell, male, 7-9 M " 4-6 oog., 22-24 M " 22-30 M long. oos., 21-23 /j. " 17-22 n " anth. cell, 6-8 ^ " 8-12 M " R. I., Conn. Europe. Subsp. IvUNDELiyii (Wittr.) Him, 1900, p. 77, PI. I, fig. 6; P. B.-A., No. 1428. Oogonia and oospores more depressed, the former subdepressed- or depressed-globose ; vegetative cells somewhat shorter and in comparison with the oogonia somewhat stouter than in the type ; oogonia solitary or two. veg. cell, female, 19-12 n diam., 3-4/4 diam. long. veg. cell, male, S-io /x " 3-4 " " oog., 22-25 <"• " 23-27 M long. oos., 19-23,0. " 15-22 M " anth. cell, 7-8 ^ <( 6-12 M " Maine, Cal. Europe. 230 TUFTS COLLEGE STUDIES, VOL. II, No. 3 3. OE. MAGNUSII Wittrock, 1874, p. 38; Him, 1900, p. 81, PI. II, fig. 14: Wittr. and Nordst., Alg. Exsicc., No. 109. Ditfecious ; oogonia single, rarely 2, depressed-globose, pore median ; oospore same form as oogoninm and fully filling it, with triple membrane ; median pitted, others smooth ; anther- idia up to 8-celled ; spermatozoid single. veg. cell, 7-10 /u diain., 1/^-4 diain. long, oog., 24-27 /j. " 21-26 /JL long, oos., 22-25 M " jS-23 M " anth. cell, S-IO-M " 5-11 M " Mass. Northern Europe. 4. OE. SUECICUM Wittrock, 18723, p. 5; Hirn, 1900, p. 82, PI. II, fig. 15. Dioecious; oogonia single, subglobose, rarely ellipsoid-globose, pore median ; oospore globose, nearl}- filling the oogonium ; epispore with subulate spines ; male plants about the same size as the female or slightly smaller ; anther- idium 2-4-?-celled, generally in the upper part of the filament ; spermatozoid single ? ; basal cell elongate, terminal cell obtuse. veg. cell, 9-14 M diaui., 3-7 diam. long, oog., 32-38 /j. " 18-26 M long, oos. with spines, 30-37/1* " 30-37 M " auth. cell, 10-12 M " 9-12 /j. " Mass. Europe, Australia, The only macrandrous dioecious species with spinous oospores. 5. OE. OBSOLETUM Wittrock, 1874, p. 9; Wolle, 1887, p. 71, PI. L,XXIV, fig. 3, PI. LXXVI, figs. 6 and 7; Hirn, 1900, p. 83, PI. II, fig. 16. Monoecious; oogonia single, sub- globose or depressed globose, pore slightly above the middle ; oospore globose or depressed-globose, not quite filling the oogonium, membrane smooth ; antheridia 1-3 celled, subepigy- nous ; spermatozoid single. veg. cell, 9-15 M diam., 3-5 diam. long. oog., 34-39 M " 34-43 ji long. oos., 30-34 M " 28-32/11 " anth. cell, 8-9 /j. " 12-16 M " Pa. Sweden. This species and the following are included only on account of Wolle's reference, which is quoted as to this species with a ? by Hirn. The two following species closely resemble it. Oe. obsoletum and Oc. plusiosporum are monoecious ; Oc. cardiacum is dioecious, and of somewhat larger dimensions. Oc. obsoletum generally has longer vegetative cells than the others, and oogonia shorter than their diameter, while Oc. plusiosporum has THE GREEN ALGAE OF NORTH AMERICA 231 a stouter aspect, and almost ellipsoidal oogonia. Of. cardiacnm has two spermatozoids in each antheridial cell, the others one spermatozoid only. 6. OE. PLUSIOSPORUM Wittrock, 1874, p. n; Wolle, 1887, p. 72, PI. LXXIV, figs. 20 and 21 ; Him, 1900, p. 84, PI. II, fig. 17. Monoecious; oogonia single, subglobose or ellipsoid- globose, pore slightly above the middle ; oospore globose or nearly so, not quite filling the oogonium, membrane smooth ; antheridia up to 6-celled, subepigynous, subhypogynous, or scattered ; spermatozoid single ; terminal cell obtuse. veg. cell, 12-19 M diam., 2-4 diani. long, oog., 34-45 ft " 35-50 ft long, oos., 30-39 ft " 3°-39 M " anth. cell, 12-14 M " 8-12 /* " Pa., N. J., Cal. Northern Europe. 7. OE. CARDIACUM (Hass.) Wittrock, 1870, p. 135; Him, 1900, p. 85, PI. Ill, fig. 19. Dioecious; oogonia single, very rarely 2, subglobose or subcordiform-globose, pore slightly above the middle ; oospore globose, not filling the oogonium, membrane smooth ; male plants slightly more slender than the female; antheridia up to lo-celled, spermatozoicls binate, division horizontal ; basal cell elongate, terminal cell obtuse. veg. cell, female, 18-30 ,udiam., 3-7 diatu. long. veg. cell, male, 15-25 M " 3-7 " " oog., 48-70 fj. " 58-78 ft long. oos., 42-60 /a " 42-60 ft " anth. cell, 15-21 ft " 10-14 M " Pa., Ontario. Europe, Africa, So. America. The range in dimensions is considerable ; in most cases the plants approach the lower limit, only rarely the upper. Var. CARBONICUM Wittrock, in Wittr. and Nordst., Alg. Ex- sicc., No. 504; Him, 1900, p. 87, PI. IV, fig. 22, is reported from Iowa by Wolle, 1887, p. 90, PI. lyXXXII, figs. 14 and 15. It has oogonia not uncommonly double, oboviform or globose- oboviform, pore higher than in the type, oospore the same form as the oogonium, and not quite filling it. 8. OE. FRANKLINIANUM Wittrock, in Wittr. and Nordst., Alg. Exsicc., No. 309; Wolle, 1887, p. 89, PI. LXXXII, figs. 7-9; Him, 1900, p. 88, PL II, fig. 18. Dioecious; oogonia single (very rarely 2), subglobose (or sub-ellipsoid-globose), pore superior ; oospore globose, almost filling the oogonium, mem- brane smooth ; male plant rather more slender than the female ; atitheridia i-3-celled ; spermatozoids 2, division horizontal. 232 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, female, 9-12 M diatii., 3-8 diani. long. veg. cell, male, S-io /j. " 3-9 " " oog., 26-31 /u " 29-41 M long. oos., 24-30 M " 24-30 n " anth. cell, 8-9 M " 5-7 /* " N. J., Pa. So. America. Resembling Oe. cardiacum, but a more slender plant, and with pore higher up on the oogonium. 9. OE. VARIANS Wittrock and Lund in Wittrock, 1874, p. ii ; Him, 1900, p. 89, PI. IV, fig. 23 ; Oe. polymorphnni Wolle, 1887, p. 73, PI. L,XXIV, figs. 16-19. Monoecious; oogonia single, very rarely 2, depressed- or subdepressed-pyriform- globose, pore nearly superior ; oospore globose, not filling the oogonium, membrane smooth ; antheridia to g-celled, scattered ; spermatozoids binate, division horizontal ; basal cell elongate, terminal cell obtuse. veg. cell, i2-i6^diam., 3-9 diam. long, oog., 35-5° v. " 34-55 /x long. OOS., 31-41 M " 30-41 fJi " anth. cell, H-I5M " 5-7 M " N. J. Europe. Characterized specially by the high position of the pore, and by the antheridia, in series of several, irregularly placed among the vegetative cells. 10. OE. FRAGILE Wittrock, 1870, p. 120 ; Wolle, 1887, p. 71, PI. LXXIV, figs. 4-6 ; Him, 1900, p. 96, PI. V, fig. 33 ; P. B.-A., No. 1477. Monoecious ; oogonia single, globose or subobovi- form-globose, pore superior ; oospore globose, filling the oogo- nium, membrane smooth ; antheridia i-3-celled, hypogynous or subepigynous ; spermatozoids binate, division horizontal ; basal cell elongate. Fig. 81. veg. cell, 12-17 M diam., 4-.7 diam. long. oog., 42-50 M " 44-55 M long. oos., 39-46 M " 39-46 M " anth. cell, 12-15 M " 10-12 M " Mass., Pa. Europe. Beside the type, Hirn notes and figures, PI. VI, fig. 34, a form, not named, from Massachusetts, with dimensions of cells, oogonia and oospores about 3 ^ more than the type ; the an- theridia may be up to 6 in a series, occurring irregularly in the filament. 11. OE. VAUCHERII (L,eCl.) A. Braun, 18553, p. 40, PI. II, fig. 13 ; Hirn, 1900, p. 97, Pi. VI, fig. 36; Wittr. and Nordst., THE GREEN ALGAE OF NORTH AMERICA 233 Alg. Exsicc., No. 20. Monoecious ; oogonia single, oboviform or suboboviform-globose, pore superior ; oospore globose or sub- globose, not quite filling the oogonium, membrane smooth, usually thick ; antheridium up to 4-celled, subepigynous or hypogynous ; spermatozoids binate, division horizontal ; basal cell elongate. veg. cell, 20-30 fj. diam., iK-4 diam. long. oog., 40-55 M " 45-65 M long. oos., 35-50 /x " 35-52 n " auth. cell, 17-24,0. " 6-ir fj. " Mass. Europe, Asia. Resembling Oc. fragile, but with vegetative cells stouter and shorter, while the oogonia are of about the same size. 12. OE. PLAGIOSTOMUM var. GRACIUUS Wittrock, 1878, p. 142; Hirn, 1900, p. 101, PI. VI, fig. 40. Dioecious; oogonia single, oboviform-globose, pore superior ; oospore globose or sub-globose, about filling the oogonium, with thick, smooth membrane ; male plant about the same size as the female ; antheridia i-5-celled, often alternating with vegetative cells; basal cell elongate. veg. cell, female, 20-25 /"diam., 2-3^ diam. long. veg. cell, male, 20-23 /"• " 2~4 " " oog., 36-42;* " 46-57 M long. oos., 34-39-" " 36-44 M " anth. cell, 19-22,". " 7-10 M " N. Y., Mexico. The type, with vegetative cells about 2 ^ thicker, oogonia and oospores 7 /j- more diam., occurs in Europe; the dimensions given above are for Mexican specimens ; those from Ithaca, N. Y., have cells a little more slender. 13. OE. FOVEOLATUM Wittrock, 1878, p. 133; Hirn, 1900, p. 106, PL VII, fig. 46. Monoecious; oogonia single, rarely 2, oboviform- or subellipsoid-globose, pore superior ; oospore glo- bose or subellipsoid-globose, filling or not quite filling the oogo- nium, membrane double, outer with net-like markings, inner smooth ; antheridia i-7-celled, hypogynous, subepigynous, or scattered ; spermatozoids binate, division horizontal ; basal cell elongate, terminal cell obtuse. veg. cell, 14-23 M diam., 2^-5 diam. long, oog., 37-49 M " 38-57 ji long, oos., 33-46 M " 34-48 M " anth. cell, 15-19 M " 8-12 M " St. Thomas. So. America. 234 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The net-like marking of the spores is found in some other species, but the only one with which there is any danger of mis- take is Oe. scrobiculatum , which can be distinguished by being dioecious, and having ellipsoid spores. 14. OE. GENICULATUM Him, 1898, p. 28 ; 1900, p. 106, PI. VIII, fig. 48 ; P. B.-A., No. 411. Monoecious ; oogonia single, slightly swollen, oboviform or oboviform-globose, pore superior; oospore not filling the oogonium, globose or sub-depressed- globose, sometimes appearing subquadrangular ; membrane thick, smooth; antheridia i-5-celled, subepigynous, subhypo- gynous or scattered, often alternating with vegetative cells. veg. cell, 37-48 M diatu., 1^-3 diam. long. oog., 56-63 fj. "' 56-67 fj. long. oos., 48-59 n " 48-59 M " anth. cell, 37-44 fj. " 5-9 /u " California. Noticeable in this species is the fact that the oogonia' pro- ject but little beyond the vegetative cells ; a few other species are similar, but they are all dioecious. 15. OE. CAPILLIFORME Kiitzing, 1849, p. 367 ; Wolle, 1887, p. 88, PI. LXXV, figs. 11-13; Him, 1900, p. 107, PL VIII, fig. 49; Roumeguere, Alg. Exsicc., No. 685, as Oe. capillare. Dioecious ; oogonia single, slightly swollen, oboviform or sub- oboviform, pore superior ; oospore ellipsoid-globose or cylin- drical-globose and appearing quadrangular, sometimes with a slight constriction at the middle, more rarely globose or sub- globose, not filling the oogonium, membrane smooth ; male plant slightly more slender than the female ; antheridia 2-5-, rarely lo-celled, often alternating with the vegetative cells ; spermatozoids binate, division horizontal ; basal cell elongate, terminal cell obtuse or apiculate. veg. cell, female, 28-38 ^ diam., iK-3 diam. long, veg. cell, male, 25-30 M " 1^-3 " " oog., 42-50 M " 51-62 /x long, oos., 37-45 /j. " 40-50 /j. " anth. cell, 20-25 /u " 8-10 M " Reported by Wolle, but questioned by Hirn as to being of the type. From St. Louis, Mo., is recorded a forma valida, one- seventh to one-tenth larger. Var. AUSTRALE Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 704; Hirn, 1900, p. 109, PI. IX, fig. 52; P. B.-A.% No. 1189; Oe. princeps Wolle, 1887, P- 93- PL IvXXVIII, fig. 3 ; THE GREEN ALGAE OF NORTH AMERICA 235 Oe. stagnate Wolle, 1887, p. 88, PL LXXXIII, figs. 3-6. Oogonia slightly less swollen and usually a little shorter, obovi- form-globose or sub-globose ; oospore globose or subglobose ; dimensions between the type and forma valida. N. Y., Mex- ico, So. Dakota, Minn., Montana, Neb., Cal., Vancouver. Africa, So. America. Forma DIVERSUM Hirn, 1900, p. no, PI. IX, fig. 54; Oe. stagnale Tilden, Amer. Algae, Nos. 122, 545. A robust form, with oospores varying from depressed-globose to cylindric-glo- bose ; filaments a third to a fourth larger than in the type. Colorado, Montana, Minn. Forma DEBARYANUM (Chmiel.) Hirn, 1900, p. 108, PI. VIII," fig. 50. Oospore usually globose or subglobose, rarely cylin- drical-globose, 38-50 /j. diam., 40-53 /* long; other dimensions slightly smaller than in the type. Greenland. Russia. A variable species, a number of other forms occurring in other countries ; we have no species for which it is liable to be mistaken, if the organs of both sexes are well developed. 16. OE. CAPiLiyARE (L.) Kiitzing, 1843, p. 255, PI. XII, figs, i-io; Wolle, 1887, p. 87, PI. I^XXXIII, figs. 7 and 8; Hirn, 1900, p. 112, PI. XI, fig. 58. Dioecious; oogonia sin- gle, little or not at all swollen, cylindrical or subcylindrical, pore superior ; oospore not filling the oogonium, globose or somewhat cylindric-globose, sometimes slightly constricted at the middle, rarely depressed-quadrangular-globose, membrane smooth ; male plant about the same size as the female or slightly less ; antheridia i-4-celled, usually alternating with vegetative cells ; spermatozoids binate, division horizontal ; basal cell elongate, terminal cell obtuse or short-apiculate. veg. cell, female, 38-55 M diam., 1-2 diam. long, veg. cell, male, 35-50 ^ " 1-2 " oog., 40-60 (L " 45-75 p. long. - oos., 30-52 M " 36-65 M " anth. cell, 30-48^ " 5-10 fj. " Only known here by the general report by Wolle, without locality. Europe. MACRANDRIA, PORIFERA, ELLIPSOSPORA. 17. OE. UPSALIENSE Wittrock, 1870, p. 125 ; Hirn, 1900, p. 115, PI. XII, fig. 60; Wittr. and Nordst., Alg. Exsicc., No. 1 8. Monoecious ; oogonia single, oboviform or suboblong- ellipsoid, pore superior ; oospore same form as the oogonium, filling the latter, membrane smooth; antheridia i-2-(rarely 3-) celled, subhypogynous ; antheridia, oogonia and vegetative cells- 236 TUFTS COLLEGE STUDIES, VOL. II, No. 3 often alternating ; spermatozoids binate, division vertical ; vege- tative cells varying much in diameter in the same filaments ; suffultory cells often larger and shorter than the others ; basal cell elongate, terminal cell obtuse. veg. cell, 13-20 M diaru., 4-8 diam. long. oog., 45-5O M " 66-100 M long. COS., 42-47 M " 60-75 M " anth. cell, 15-18 M " 7-10 fj. " Greenland, N. H., Michigan. Europe. A special character of this species is the variation in size of the cells in the same filament. The cells under the oogonia are the stoutest and shortest, those directly over the oogonia the longest and most slender. The antheridial cells are vety sel- dom over 2 in a series. 18. OE. RICHTERIANUM Lenimerman, 1895, p. 26, figs. 1-3; Him, 1900, p. 117, PI. XII, fig. 63 ; P. B.-A., No. 1429. Monoecious ; oogonia single or 2, oboviform or subellipsoid, pore superior ; oospore suboboviform or subellipsoid, rarely globose-ellipsoid, quite or nearly filling the oogonium, mem- brane smooth; antheridia i-6-celled, subhypogynous, subepi- gynous or scattered ; spermatozoids binate, division horizontal ; basal cell usually elongate. veg. cell, 12-21 ,u diam., 3-6K diaru. long, oog., 36-48^ " 48-74 /"long, oos., 35-43 M " 43-59 M " anth. cell, 12-15 M " 6-9 /"• " Mass. Europe. 19. OE. RIVULARE (LeCl.) A. Braun, i855a, p. 23, PI. I, figs, i-io; Wolle, 1887, p. 92, PI. LXXXIII, figs, i and 2 ; Him, 1900, p. 119, PL XII, fig. 66; Phyk. Univ., No. 70. Dioecious ; oogonia single or 2-7-seriate, oboviform, pore superior ; oospore oboviform, ellipsoid or subglobose, not nearly filling the oogonium, membrane smooth; male plant somewhat more slender than the female ; antheridia to i3-celled; sperma- tozoids binate, division horizontal ; basal cell elongate. veg. cell, female, 35-45 ^diam., 3-8 diam. long, veg. cell, male, 30-36 y. " 4-8 " oog., 70-85 M " 130-160 M long. OOS., 55-/0 M " 65-100 M " anth. cell, 21-28 M " 14-26 M " Iowa, Florida. Northern Europe. A large species, easily recognizable by the size, the oogonia man)- in a series, and the oospore much smaller than the oogo- THE GREEN ALGAE OF NORTH AMERICA 237 ilium ; the aiithericlia are usually many in a series. Wolle's reference appears to be the only authority for its occurrence in America. 20. OE. PALUDOSUM (Hass.) Wittrock, 1870, p. 124; Wolle, 1887, p. 74, PI. LXXV, fig. i ; Him, 1900, p. 120, PI. XIII, fig. 69. Monoecious; oogonia single, ellipsoid, pore superior; oospore ellipsoid, filling the oogonium, membrane triple, outer and middle layers with longitudinal lines, 27-35 in number, con- tinuous, rarely anastomosing ; antheridia i-8-celled, scattered, often in the upper part of the filament ; spermatozoids binate, division vertical. veg. cell, 15-20 fj. diain., 3-7 diam. long, oog., 39-48 fj. " 66-84 M long oos., 36-45 M " 54-63 M " anth. cell, 14-16 M " 6-13 /u. " Type reported by Wolle from Pa., but questioned by Him. Northern Europe. Var. AMERICANUM Norclstedt in Him, 1900, p. 121, PI. XIII, fig. 72. Oogonia larger, ellipsoid; oospore of same shape, fill- ing- the oogonium. veg. cell, 14-23 M diam., 3-7 diam. long, oog., 54-63 M " 75-9° M !°ug- oos., 49-57 M " 69-75 M " anth. cell, 12-18 p. " 7-12 (j. " So. Carolina. The peculiar sculpture of the spore is sufficient to distinguish this and the following species from all others. The outer sur- face of the external membrane is smooth, but its inner surface and the outer surface of the median membrane are marked with longitudinal lines, arranged like the meridians of a sphere. The two species are distinct in the arrangement of the organs of fructification, Oc. paludosum being monoecious, Oe. Boscii dioe- cious. 21. OE. BOSCII (LeCl.) Wittrock, 1870, p. 136; Wolle, 1887, p. 91, PI. LXXXII, figs. 11-13; Hirn, 1900, p. 122, PI. XIII, fig. 73; Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 1213. Dioecious; oogonia single (very rarely double) oblong- ellipsoid, pore superior; oospore ellipsoid, not nearly filling the oogonium ; marked as in Oc. paludosnui ; male plant somewhat more slender than the female. 238 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, female, 14-23 M diam., 3-6 diam. long. veg. cell, male, 13-18 M " 4-6 " oog., 39-51 M " 75-110 M long. oos., 36-43 M " 56-70 M " anth. cell, 13-14 M " 6-16 M " Greenland, Mass., Conn., Cal. Europe, So. America. Forma DISPAR Him, 1900, p. 124, PI. XIV, fig. 76 ; P. B.-A., No. 1226. Oospore smaller, ellipsoid-globose or sub-globose; oogonia shorter, sometimes suboviform. veg. cell, 14-21 ,u diam., 4-7 diam. long. oog., 38-45 /j. " 70-92 M long. oos., 34-43 M " 44-55 fj. " Mass., Pa., Cal. Var. OCCIDENTALS Him, 1900, p. 125, PI. XIV, fig. 77. More slender in all parts, vegetative cells longer ; male plant same diameter as the female. veg. cell, female, 8-15 M diam., 6-n diam. long. veg. cell, male, 8-15 M " 6-u " " oog., 33-38 fj. " 75-100 fj. long. oos., 32-37 fj. " 45-50 fj. " anth. cell, 12-13 n " 10-16 M " Kittery, Maine. 22. OE. MARGARITIFERUM Nordstedt and Him in Him, 1900, p. 128, PI. XV, fig. 83. Dioecious; oogonia single, sub- oblong or suboviform-ellipsoid or subellipsoid, pore superior; oospore ellipsoid or globose-ellipsoid, not nearly filling the oogonium, or rarely nearly filling it ; membrane triple, with longitudinal lines on the inner surface of the outer membrane and the outer surface of the median membrane ; lines 30-35, sometimes anastomosing, not continuous, but made up of some- what elongate dots ; male plant somewhat more slender than the female ; antheridia to lo-celled ; spermatozoids binate, divi- sion vertical. veg. cell, female, 23-28 /u diam., 3/4-7 diam. long. veg. cell, male, 17-23 fj. " 4^-7 " " oog., 50-63 M " 82-100 M long. oos., 48-61 fj. " 55-75 M " auth. cell, 18-20 M " 7-13 ^ " So. America. Hirn considers as probably belonging to this species the plant figured by Wood, 1872, PI. XVIII, fig. 4, but not named, and on this probability it is here included. It varies considerably in the size and shape of the oogonium and oospore, but on care- THE GREEN AI«GAE OF NORTH AMERICA 239 fill examination should be easily distinguished by the dotted, not continuous " meridians " on the spore. 23. OE. CRENULATO-COSTATUM Wittrock, 1878, p. 139; Him, 1900, p. 129, PI. XV, fig. 84; P. B.-A., Nos. 810, 1426. Dioecious; oogonia single or 2-3, rarely 4-5, oboviform or subellipsoid, rarely oblong-ellipsoid, pore superior; oospore same form as the oogonium, filling or nearly filling the latter, membrane triple, external membrane smooth, median mem- brane with 14-20 longitudinal, crenulate, sometimes anastomos- ing lines ; male plant somewhat more slender than the female ; antheridia 2-6-celled, often alternating with vegetative cells ; spermatozoids binate, division horizontal ; terminal cell, which not infrequently is an oogonium, obtuse or short-apiculate. veg. cell, female, 10-18 M diam., 2^-7 diam. long. veg. cell, male, 9-13 /j. " 3^-6 " " oog., 3°-36 /"• " 40-65 M long. oos., 28-34 M " 37-55 M " anth. cell, 9-12 /j. " 9-14 n " Mass., Conn., N. Y., Pa. Forma CYUNDRICUM Him, 1900, p. 129, PI. XV, fig. 85 ; P. B.-A., No. 118, as Oe. Boscii. Ooogonia and oospores of variable form, generally cylindric-oblong, rarely ellipsoid or obovate-ellipsoid ; longitudinal lines slightly crenate or almost entire ; oogonia single or 2-4 ; vegetative cells slender. veg. cell, 11-16 /* diarn., 4-10 diam. long. oog., 30-36 fj. " 42-81 M long. oos., 2 7-34 M " 40-65 n " Mass., Conn., Mo. Var. AUREUM Tilden, Amer. Algae, No. 123; 1898, p. 90, PI. VIII, fig. 1-3 ; Him, 1900, p. 130, PI. XV, fig. 87. Slender, oogonia shorter than in the type, single or 2-3 ; oospore obovoid to globose-ellipsoid, not quite filling the oogonium ; lines of the oospore only scantily toothed, connected by distinct cross-lines. veg. cell, 10-13 /a diam., 3/^-9 diam. long, oog., 30-35 ^ " 38-50 M long. oos., 29-33 /* " 35-43 M " In warm water, Yellowstone National Park. The peculiar character of the "meridians' identifies this species in its various forms, much as the latter differ in other particulars. Him thinks it probable that under this name should be included Oe. apiculatwn Wolle, 18773, p. iSS. 24. OE. TAPHROSPORUM Nordstedt and Him in Hirn, 1900, 240 TUFTS COLLEGE STUDIES, VOL. II, No. 3 p. 133, PI. XVI, fig. 91; P. B.-A., No. 813. Dioecious; oogonia 2-6 or single, oboviform or oboviform-ellipsoid, pore superior ; oospore globose or ellipsoid- globose, not filling or nearly filling the oogonium, membrane double, outer membrane pitted, inner smooth ; male plants about the same size as the female ; antheridium 2-?-celled ; terminal cell, which sometimes is an oogonium, obtuse. veg. cell, female, 25-38 M diam., 4-10 diani. loug. veg. cell, male, 26-33 /* " 4-9 " " oog., 70-83 /J. " 81-113 M long. oos., 58-65 M " 62-70 /j. " anth. cell, 24-32 /j. " 8-12 /u " Mass. So. America. 25. OE. PUNCTATUM Wittrock, 1878, p. 142; Hirn, 1900, p. 132, PI. XV, fig. 89. Dioecious; oogonia 2-4-seriate or single, oboviform, rarely globose-oboviform, pore superior ; oospore oboviform, almost filling the oogonium, rarely subglo- bose, and then not filling the oogonium, membrane double, outer membrane densely pitted, inner membrane smooth ; male plants about the size of the female ; antheridia i-5-celled, often alternating with the vegetative cells ; spermatozoids binate, division horizontal ; basal cell elongate ; terminal cell, which is frequently an oogonium, obtuse. veg. cell, female, 15-22 /udiam., 3-6 diam. long. veg. cell, male, 15-22 n " 3-6 " " oog., 38-45 fj. " 52-65 M long. oos., 37-43 M " 43-55 <" " auth. cell, 15-17^ " 6-10 M " Vera Cruz, Mexico. A species closely resembling this, Oc. scrobiculatum Wittr., has been described from Equador ; the dimensions are somewhat larger, the vegetative cells in the female plant ranging from 16-30 fj. ; the oogonia are usually solitary. 26. OE. MARTINICENSE Hirn, 1900, p. 134, PI. XVI, fig. 92 ; Oe. crassum Wolle, 1887, p. 74, PL L,XXVI, figs. 2 and 3. Monoecious ; oogonia single, oboviform or suboboviform, pore superior ; oospore oboviform or oboviform-ellipsoid, almost fill- ing the oogonium, membrane smooth, usually rather thick ; antheridia i-5-celled, hypogynous ; spermatozoids binate, divi- sion vertical. veg. cell, 33-37 ^ diam., 3/^-6>^ diam. long, oog., 68-74 n " 96-124 ^ long, oos., 66-72 fj. " 81-96 M " anth. cell, 33-35 n " 5-7 M " Iowa, Kansas, Island of Martinique. THE GREEN AI«GAE OP NORTH AMERICA 241 Resembles Oe. Landsboroughii, but the latter is dioecious. 27. OE. L/ANDSBOROUGHII (Hass.) Wittrock, 1874, p. 35; Wolle, 1887, p. 91, PI. LXXXI, figs. 8-n; Him, 1900, p. 135, PI. XVI and XVII, fig. 94; P. B.-A., No. 663. Dioe- cious; oogonia single, rarely 2, oboviform or suboboviform, pore superior ; oospore oboviform to ellipsioid, filling or not quite filling the oogonium, membrane smooth ; male plant gen- erally a little more slender than the female ; antheridia to 25- celled ; spermatozoids binate, division vertical ; basal cell elongate, apical cell obtuse. veg. cell, female, 31-40 /u. diam., 3-6 diam. long. veg. cell, male, 30-37 v- " 4-6 oog., 63-75 fj. " 85-110^ long. j oos., 59- 7° M " 73-102 M " auth. cell, 27-35 /u " 9-20 n " Mass., Conn., N. Y., Mexico. Europe, So. America. A widely distributed species, and varying somewhat, but not as much as some other species ; a form has been found in Mex- ico with veg. cells 37-51 /«• diam., otherwise like the type.* 28. OE. OBOVIFORME Wittrock, 1878, p. 140; Him, 1900, p. 141, PI. XX, fig. 103. Dioecious; oogonia single, obovi- form, pore superior; oospore oboviform, about filling the oogonium, rarely ellipsoid-oboviform, and then not quite filling the oogonium, membrane smooth ; male plant about the same size as the female ; antheridia to ig-celled ; spermatozoids binate, division vertical ; basal cell elongate. veg. cell, female, 21-33 /a diam., 3/^-9 diam. long, veg. cell, male, 21-31 /x " 3/4-9 oog., 55-65 fj. " 80-107 fj. long, oos., 54-61 ij. " 70-85 M " anth. cell, 21-28 /j. " 5-13 /* " Vera Cruz, Mexico. So. America. Quite close to Oe. grande, but distinguished by the obovi- form oogonia. 29. OE. PACHYANDRIUM Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 5 ; Wolle, 1887, p. 89, PI. LXXV, figs. 9 and 10 ; Hirn, 1900, p. 142, PI. XX, fig. 104. Dioecious; oogonia single or rarely 2, very rarely 3, suboboviform or *Wolle, 1887, p. 92, PL I/XXVI, figs. 7 and 8, describes anew var. major of Oe. rivulare (L,eCl.) A.Br.; Hirn, 1887, p. 141, thinks that this may belong under Oe. crassum, forma amplum (Magn. & Wille) Hirn ; re- sembling Oe. Landsboroughii, but of larger dimensions; the dimensions given by Wolle are, however, larger than anything recorded for any form of Oe. crassum. 242 TUFTS COLLEGE STUDIES, VOL. II, No. 3 oboviform-ellipsoid, pore superior; oospore ellipsoid, not filling the oogonium, membrane smooth ; male plant generally some- what stouter than the female; antheridia i-4-celled; spermato- zoids binate, division vertical. veg. cell, female, 30-36 M diam., 3-6/^ diam. long, veg. cell, male, 32-45 » " 2-3^ " oog., 53-47 M " 84-108 M long, oos., 51-57 M " 69-85 M " anth. cell, 30-43 M " 11-20 M " Pa. and N. J., according to Wolle, but questioned by Him. The species so much resembles forms of Oe. grande that it is quite possible that Wolle's plants were really the latter, which occurs at a number of American stations. 30. OE. GRANDE Kiitzing, 1845, p. 200; Wolle, 1887, p. 95, PI. LXXVI, fig i ; Him, 1900, p. 143, PI. XXI, fig. 105 ; P. B.-A., No. Sn. Dioecious; oogonia single, rarely 2-5, slightly swollen, suboboviform, pore superior ; oospore same form as the oogonium, not quite filling it, membrane smooth ; male plant slightly more slender than the female ; antheridia i-8-celled ; spermatozoids binate, division vertical ; basal cell elongate. veg. cell, female, 28-37 n diam., 2^-5 diam. long, veg. cell, male, 28-33 /* " 2^-5 oog., 49-60 n " 86-100 M long, oos., 47-58 M " 64-93 ^ " anth. cell, 25-33 ,u " n-iS M " Ontario, Me., Mass., Conn., Pa., Cal. Europe, Australia. A species of varying forms, some of which have received names in Hirn's monograph, some being only mentioned, with- out name. Among the latter is the form from Massachusetts, distributed as P. B.-A., No. 519, with veg. cells 4-11 diam. long, oogonia up to 126 p. long, oospores to 104 /*, the diameter about as in the type ; while among the named varieties is Var. ANGUSTUM Him, 1900, p. 146, PL XXI, fig. no; P. B.-A., No. 410. Slender, veg. cells and oogonia elongate, antheridia to 36 cells, oogonia sometimes 4 in succession. veg. cell, female, 19-30 p. diam., 3/^-11 diam. long, veg. cell, male, 19-25 M " 4-9 oog., 42-52 /u " 62-1 10 M long, oos., 40-50 fj. " 60-89 M " anth. cell, 18-22 M " 7-15 M " Mass. So. America. THE GREEN ALGAE OF NORTH AMERICA 243 Var. AEQUATORIALE forma HORTENSE Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 1017 ; Hirn, 1900, p. 145, PI. XXI, fig. 109. Smaller than the type in all parts, oosporesless completely filling the oogonium, sometimes globose-ellipsoid, and then not nearly filling the oogonium. veg. cell, female, 24-33 M diam., 2-4 /4 diani. long. oog., 42-5 1 n " 63-88 M long. oos., 38-49 fj. " 48-72 A* " These measures are for forma hortense ; in the variety the vegetative cells and oogonia are proportionately longer. Green- laud. Ecuador. 31. OE. MEXICANUM Wittrock, 1878, p. 138; Hirn, 1900, p. 147, PI. XXII, fig. in; Tilden, Amer. Algae, No. 257. Dioecious; oogonia single, slightly swollen, cylindric-obovi- form, pore superior ; oospore of the same form as the oogo- nium, filling or nearly filling it, membrane smooth ; male plant a little more slender than the female ; antheridia to 8-celled ; spermatozoids binate, division vertical. veg. cell, female, 34-41 M diam., i^-3/^ diam. long. veg. cell, male, 30-38 A4 " 2-3 oog., 53-63 <" " 76-110 At long. oos., 51-60 /j. " 63-80 M " anth. cell, 28-35 /a " 7-17 fj. " Mass., So. Dakota, Mexico. Ne*arly related to Oe. grande, but with vegetative cells aver- aging larger and considerably shorter, oogonia more nearly cylindrical, and more completely filled by the oospore. MACRANDRIA, OPERCULATA, GLOBOSPORA. 32. OE. PUNCTATO-STRIATUM De Bary, 1854, p. 47, PI. II, figs. 15 and 16; Wolle, 1887, p. 91, PI. LXXXV, figs. 3-5; Hirn, 1900, p. 152, PL XXIII, fig. 123; Rabenhorst, Algen, Nos. 214, 2276. Diocecious ; oogonia single, depressed-globose, operculate, division median ; oospore depressed-globose, not quite filling the oogonium, membrane smooth ; male plant slightly more slender than the female ; antheridia to lo-celled, cells slightly swollen ; spermatozoid single ; membrane of the vegetative cells and oogonia marked with spirally placed dot- like pores ; basal cell depressed-globose or subhemispherical, not elongate, membrane vertically plicate. 244 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, female, 18-22 /x diam., 2-6 diam. long. veg. cell, male, 16-19x1 " 2-6 " " oog., 48-55 /x " 38-48 /x long. oos., 40-51 xi " 35-43 M " anth. cell, 16-19 M " 6-12 /x " basal cell, 28-31 xi " 21-25 M " Greenland, Florida. Europe, So. America. Quite distinct from other American species, by the spiral markings of the cell walls, as well as by other characters. The Florida locality, Wolle's determination, is perhaps doubtful. 33. OE. HOWARDII G. S.West, 1904, p. 281, PI. CCCCLXIV, figs. 1-5. Dioecious; oogonia solitary, globose or subglobose, operculate, division median ; oospore globose or sub-depressed- globose, filling the oogonium ; antheridia pluricellular ; sper- matozoid single ; vegetative cells slightly but distinctly capitel- late ; basal cell of filament subhemispherical or subspherical, not elongate. veg. cell, female, 9.5-11 xt diam. 2-4 diam long. veg. cell, male, 7-5-9 M • " 2-4 " " oog., 29-33 xc " 29-33 x<. long. oos., 25-29 /x " 25-29x1 " anth. cell, 7-5-9 <" " 8-14x1 " basal cell, 14-16x1 " 10-11 xt " Barbados. With basal cell similar to Oe. pnnctato-striatum, but smaller in all dimensions, and without the spiral markings of the latter species. 34. OE. PITHOPHORAE Wittrock, 1878, p. 141 ; Him, 1900, p. 157, PI. XXIV, fig. 134. Monoecious ; oogonia single, pyri- form-globose, operculate, division superior; oospore globose, almost filling the oogonium, membrane smooth, often thickish ; antheridia i (or more ?)-celled, subepigynous ; basal cell elon- gate. veg. cell, 9-11 tt diam., 2^-4^ diam. long, oog., 26-30 xi " 27-35 xt long, oos., 25-29 xc " 24-29 xc " anth. cell, S-io /x " 7-9 xi " St. Thomas, W. I., epiphytic on Pithophora Cleveana. 35. OE. CRISPUM (Hass.) Wittrock, 1874, p. 10 ; Wolle, 1887, p. 72, PI. lyXXIV, figs. 11-15; Hirn, 1900, p. 159, PL XXV, fig. 138; Wittr. and Nordst., Alg. Exsicc., Nos. 209, 508 ; Tilden, American Algae, No. 543. Monoecious; oogonia single, very rarely 2, oboviform-globose, operculate, division THE GREEN ALGAE OF NORTH AMERICA 245 superior ; oospore globose or subglobose, almost filling the oogonium, membrane smooth ; antheridium i-5-celled, subepi- gynous or hypogynous ; spermatozoids binate, division hori- zontal ; basal cell elongate, terminal cell obtuse. veg. cell, 12-16 n diam., 3~4/^ diam. long, oog., 37-45 M " 41-53 M !oQg- oos., 35-43 V- " 37-43 M " anth. cell, 8-14 p. " 7-12 M " Greenland, Pa., Vancouver, Minn., Alaska, Cal. Europe, Asia, Africa, Australia, So. America. Perhaps the commonest and most widely distributed species of the. genus, and including many varieties and forms, two of which occur within our limits. Var. GRACILESCENS Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 509 ; Him, 1900, p. 162, PI. XXV, fig. 143 ; P. B.-A., No. 518. Slender, oogonia and oospores varying in form, oogonia oboviform-globose to oboviform-pyriform or sub- ellipsoid, generally single, rarely 2 or 3 ; oospores globose to ellipsoid. veg. cell, 10-14 M diam., 3-5 diam. long. oog., 33-39 M " 33-51 M long. oos., 32-37 M " 33-42 fj. " anth. cell, 9-10 /j. " 7-9 /u " Mass., Minn., (Pa.?), Mo. So. America. The Pa. locality is surmised from Wolle's figure, which may represent this variety, though given as Oe. vernale (Hass.) Wittr. Var. URUGUAYENSE Magnus and Wille in Wille, 1884, p. 39, PL II, fig. 63; Him, 1900, p. 164, PI. XXVI, fig. 145; Wittr. and Nordst., Alg. Exsicc., No. 311, as Oe. crispum f. typtcuTn. Smaller, veg. cells shorter, oogonia single, subobovi- form-globose ; oospore filling the oogonium ; antheridia subepi- gynous, hypogynous or sometimes scattered. veg. cell, 10-14 M diam., 1^-3^2 diam. long, oog., 3°-38 M " 33-43 M long, oos., 27-35 /j. " 27-37 M '" anth. cell, 8-13 t* " 6-12 /* " Pa. So. America. 36. OE. OBESUM (Wittr.) Him, 1900, p. 166, PI. XXVI, fig. 148. Monoecious; oogonia single, oboviform-globose, oper- culate. division superior ; oospore globose, not quite filling the oogonium, membrane smooth, often thickened ; antheridia 1-2- 246 TUFTS COLLEGE STUDIES, VOL. II, No. 3 celled, subepigynous or more rarely subh)Tpogynous ; sperniato- zoids binate, division horizontal. veg. cell, 12-15 i" diam., . 2/4~5 diaui. long. oog., 40-43 M " 38-44 M long. oos., 33-35 M " 33-35 /x " anth. cell, 11-14 M 10-15 n " Mass. Europe. Resembles Oc. crispum, but the oospores are smaller in pro- portion to the oogonia, and the oogonia are always solitary ; from Oc. autumnalc it is distinguished by the smaller but longer vegetative cells. 37. OE. AUTUMNALE Wittrock, 1874, p. ii ; Wolle, 1887, p. 73, PI. LXXXI, figs. 1-5; Him, 1900, p. 167, PI. XXVI, fig. 151. Monoecious ; oogonia single, oboviform-globose, opercu- late, division superior ; oospore globose or subglobose, filling or nearly filling the oogoniurn, membrane smooth ; antheridia 1-2- celled, subepigynous, hypogynous or scattered ; spermatozoids binate, division horizontal ; basal cell elongate, terminal cell shortly acute. veg. cell, 16-20 fj. diam., 1/4-2 YZ diam. long. oog., 39-45 /x " 45-51 M long. oos., 37-42 M " 37-44 M " anth. cell, 15-18 y. " 9-10 fj. " Pa. Europe. Not far from Oc. crisp u in, but with stouter and shorter vege- tative cells, and relatively less swollen oogonia. Its occurrence in America has no other proof than the reference in Wolle. 38. OE. PRINGSHEIMII Cramer, 1859, p. 17, PL I, figs. 1-4; Wolle, 1887, p. 90, PI. LXXXII, figs. 4-6; Him, 1900, p. 170, PI. XXVII, fig. 155; Rabenhorst, Algen, No. 790. Dioe- cious ; oogonia 2-6-seriate or single, suboboviform-globose, operculate, division superior ; oospore globose, almost filling the oogonium, membrane smooth, thickish ; male plant slightly more slender than the female ; antheridia to lo-celled, always alternating with vegetative cells ; spermatozoids binate, divi- sion horizontal ; basal cell elongate, terminal cell obtuse or short-apiculate. veg. cell, female, 14-20 /j. diam., 2-5 diam. long, veg. cell, male, 12-16 /u " 2-4 " ." oog., 35-43 fj. " 36-46 M long, oos., 3°-37 /" " 3°-37 M " anth. cell, 11-15 /* " 6-9 M " N. Y., Pa., Florida. Europe, Africa, Australia. THE GREEN ALGAE OF NORTH AMERICA 247 A widely distributed species, but the occurrence with us of the typical form is recorded only by Wolle, who does not men- tion var. Nordstcdtii, which certainly does occur here ; possibly his plants belong rather to the variety. Var. NORDSTEDTII \Vittrock in Wittr. and Nordst., Alg. Exsicc., Nos. 8 and 205; Him, 1900, p. 171, PI. XXVII, fig. 156. Smaller, oogonia single, rarely 2, oboviform-globose, oospore not quite filling the oogoniutn. veg. cell, female, 10-16 M diam., 2-4}^ diam. long. veg. cell, male, 9-15 M " 2-4^ " oog., 28-39 fj. " 36-45 Mong. oos., 26-34 n " 27-34 M anth. cell, 9-12 /* " 8-9 n " Greenland, Minnesota, Cal. Europe, Asia. MACRANDRIA, OPERCULATA, ELLIPSOSPORA. 39. OE. AHLSTRANDII Wittrock in Wittr. and Nordst., Alg-. Exsicc., No. 401 ; Him, 1900, p. 183, PI. XXIX, fig. 179. Monoecious; oogonia ellipsoid, single, operculate, division su- perior ; oospore ellipsoid, filling the oogonium, membrane smooth; antheridium i-2-celled, hypogynous ; spermatozoids binate, division horizontal : terminal cell obtuse. veg. cell, 10-18 M diain., 3-10. diam. long, oog., 34-42 M " 57-69 M long. COS., 34-41 M " 53-62 fJ. " anth. cell, 13-17 M " 9'12 /" " N. Y. Sweden. 40. OE. GRACiivLiMUM Wittrock and Lund in Wittrock, 1874, p. 15 ; Wolle, 1887, p. 74, PI. LXXV, fig. 2 ; Him, 1900, p. 184, PI. XXIX, fig. 180. Monoecious; oogonia single, oblong, operculate, division superior ; oospore oblong-ellipsoid, not filling the oogonium, membrane smooth ; antheridia subepi- gynous, hypogynous or subhypogynous, unicellular ; spermato- zoids binate, division horizontal. veg. cell, 3^-7 ^diam., 4^-6 diam. long, oog., 14-19 M " 34-40 /j. long, oos., 13-17 /"• " 24-32^ " anth. cell, 3-5 M " 4'7 /* " Pa. Europe. 41. OE. NODULOSUM Wittrock, 1872, p. 22, PL I, figs. 8-10 ; Him, 1900, p. 187, PI. XXIX, fig. 184. Monoecious; oogonia single or 2, oboviform-globose, more rarely oboviform-ellipsoid, operculate, division superior ; oospore globose or subglobose, more rarely globose-ellipsoid, almost filling the oogonium, mem- 248 TUFTS COLLEGE STUDIES, VOL. II, No. 3 brane smooth, often thick ; antheridia i-3-celled, subepigynous or hypogynous ; spermatozoids binate, division horizontal ; vegetative cells with two undulate constrictions ; basal cell elongate, not constricted ; terminal cell obtuse or apiculate. veg. cell, 20-29 P diam., i/^-4/^ diatn. long. oog., 48-57 <"• " 56-73 . M long. oos., 46-53 M " 49-56 M " anth. cell, 18-25 /u, " 7-9 fj. " The type occurs in Europe, Asia, Australia, and So. America, but has not been reported from No. America ; but we have Var. COMMUNE Him, 1900, p. 187, PI. XXX, fig. 185; P. B.-A., No. 74, as Oe. nodulosum. Oogonia and oospores larger, the former suboboviform-ellipsoid to ellipsoid, more rarely globose-ellipsoid. veg. cell, 22-29 /"• diam., iK-4/^ diam. long, oog., 64-74^ " 70-90 /along. • oos., 56-70 M " 67-80 /j. " anth. cell, 18-26 M " 7-10 //. " Mass. Finland. The specific name is due to the constrictions in the vegetative cells, each cell appearing to consist of three parts, separated by necks. No other American species has this character. 42. OE. NOBILE Wittrock, 1874, p. 14; Hirn, 1900, p. 189, PI. XXX, fig. 188. Monoecious; oogonia single, very rarely 2, ellipsoid or suboboviform-ellipsoid, operculate, division superior ; oospore ellipsoid-globose or globose, not filling the oogonium, membrane triple ; outer membrane smooth, median membrane with 30-35 continuous longitudinal lines, rarely anas- tomosing, inner membrane smooth ; antheridia i-3-celled, hypo- gynous ; spermatozoids binate, division horizontal. veg. cell, 16-20 /j. diam., 5-9 diam. long. oog., 57-65 M " 67-90 M long. oos., 48-55^ " 67-79 /u. " anth. cell, 18-19 /u " 9-13 n " The dimensions given are of the type occurring in Norway ; the American form, occurring in Mass., has dimensions as follows : — veg. cell, 14-20 fj. diam., 6-n diam. long. oog., 57-63 M " 81-95 ^ long. oos., 55-60 M " 67-79^ " anth. cell, 14-19 M " 13-17 M " As the characters otherwise agree, the form does not seem to require a special name. This species has the spore membrane THE GREEN ALGAE OP NORTH AMERICA 249 similar to that of Oc. Boscii, but is distinguished by the opercu- late oogonium, as well as by other characters. NANNANDRIA, ANTHERIDIUM EXTERIUS, PORIFERA, GLOBOSPORA. 43. OE. BRAUNII Kiitzing, 1849, p. 366; Wolle, 1887, p. 79, PI. LXXIX, figs. 6 and 7 ; Him, 1900, p. 194, PI. XXXII, fig. 197; Wittr. and Nordst., Alg. Exsicc., No. 15. Dioecious, nannandrous, gynandrosporous ; oogonia single, ellipsoid or subglobose, pore median ; oospore globose, not quite filling the oogonium, membrane smooth ; suffultory cell slightly or not swollen ; androsporangia i-2-celled ; basal cell elongate, ter- minal cell obtuse ; dwarf males near the oogonia, often on the suffultory cell, stipe sometimes 5-celled, antheridium external, unicellular, stipe slightly curved. veg. cell, 13-15 M diam., 2-4 diam. long, suf. cell, 16-20 ^ " i&-2# " oog., 30-37 it. " 33-43 /x long, oos., 27-33 M " 27-33 M " andr. cell, 13-15 M " 11-12 M " nan. stipe, 7-12 /j. " 20-28 M " anth. cell, 5-8 ^ " 9-10 M " N. J., Pa. Europe, Africa. 44. OE. FLAVESCENS (Hass.) Wittrock, 1870, p. 127, PI. LIU, fig. 9; Wolle, 1887, p. 78, PI. IvXXVIII, figs, i and 2; Him, 1900, p. 196, PI. XXXII, fig. 199. Dioecious, nannan- drous, idio- or gynandrosporous ; oogonia single, ellipsoid or subglobose (sometimes sub-hexagonal-globose), pore median ; oospore globose, not quite filling the oogonium, membrane smooth; suffultory cell similar to other veg. cells; androspor- angia i-9-celled ; dwarf males slightly curved, on the suffultory cell, antheridium external, i- (or 2-) celled. veg. cell, 18-23 IJL diam., 4-6 diani. long. oog., 49-52 /j. " 51-60 M long. oos., 45-49 /* " 45-49 /* " andr. cell, 17-20 M " 8-18 /* " nan. stipe, 11-12 M " 36-45 /u. " anth. cell, 9-10 ju. " 15-20 M " Mass., Minn. Sweden. Somewhat like the preceding species in character, but of larger dimensions ; the oogonium is often of hexagonal form when young, later becoming globose. 45. OE. PUNGENS Him, 1900, p. 199, PI. XXXII, fig. 203. 250 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Dioecious, nannandrous, gynandrosporous ; oogonia single, de- pressed-globose or subglobose, pore median or slightly higher ; oospore subglobose, nearly filling the oogoniurn, epispore cov- ered with subuliform spines ; suffultory cell similar to other veg. cells; androsporangia hypogynous, i- (or more-?) celled; dwarf males slightly curved, on the suffultory cells, antheridium external, i-2-celled. veg. cell, 12-16 M diam., 4-6 diam. long, oog., 40-48 M " 40-50 M long, oos., 37-44 /u " 35-43." " andr. cell, 14-16 M " 10-15 M " nan. stipe, 9-12 M " 20-30 /x " anth. cell, 6-7 M " 8-12 M " So. Carolina. This species was collected by Ravenel, but the specimen re- mained unnoticed until Hirn found it and published it in his Monograph in 1900. It is quite similar in character to Oe. aster, a Swedish plant, also of a single station, which has a similar spinous oospore, but is smaller in all its dimensions, with longer cells ; Oe. echinospermum has similar spines on the oospore, but has stouter vegetative cells, so that the oogonia do not appear so swollen ; they are moreover ellipsoid instead of depressed. 46. OE. ECHINOSPERMUM A. Braun in Klitzing, 1849, p. 366; Wolle, 1887, p. 86, PL LXXXIV, fig. 7; Hirn, 1900, p. 199, PI. XXXIII, fig. 204; Wittr. and Nordst., Alg. Exsicc., Nos. 12, 506. Dioecious, nannandrous, gynandro- oridioandro- sporous ; oogonia single, ellipsoid-globose or subglobose, pore median ; oospore globose, almost filling the oogonimn, epispore with subulate spines ; suffultory cell not swollen ; androspor- angia i-5-cellecl, dwarf males slightly curved, on the suffultory cell, antheridium external, i-2-celled. veg. cell, 18-30 /JL diam., 2)4-4)4 diam. long, oog., 39-50," " 41-57 Mlong. oos., 38-47 /u " 38-49 p. " andr. cell, 21-25 M " 9^5 M " nan. stipe, 10-15 M " 26-35 M " anth. cell, 6-12 n " 6-15 M " Mass., N. Y., N. J., Pa. Europe. Var. HORRIDUM Hirn, 1900, p. 201, PI. XXXIII, fig. 205; Oe. echinospermum var. ? Wolle, 1887, p. 86, PI. LXXXV, THE GREEN ALGAE OF NORTH AMERICA 251 figs. 6-9. Larger, spines of the oospore longer and denser; antheridiuni pluricellular. Florida. The distinctions between Oe. echinospermum and Oe. pungens were given under the latter species ; the var. horridum has quite a different appearance from the type, and when better known may prove to be a distinct species. 47. OE. IRREGULARS Wittrock, 1870, p. 128; Wolle, 1887, p. 79, PI. LXXVIII, figs. 4 and 5 ; Hirn, 1900, p. 202, PI. XXXIII, fig. 207. Dioecious, nannandrous ; oogonia single, globose or subdepressed-globose, pore superior ; oospore globose, filling the oogonium, membrane smooth ; stiff ultory cell not swollen ; dwarf males straight, near or on the oogonium ; an- theridiurn exterior, i-4-celled. veg. cell, 15-20 /JL diam., 2^-4 diam. long. oog., 37-45 M " 36-47 M long. oos., 36-42 /x " 34-41 /x " nan. stipe, 12-15 M " 20-24 /j. " anth. cell, 10-12 /* " 6-8 ^ " Florida. Northern Europe. This species is in habit much like the monoecious Oe. fragile ; the globose oogonia often occur throughout a long vegetative filament, with only one or two vegetative cells between ; the short dwarf males are usually at right angles to the filament. 48. OE. ARMIGERUM Hirn, 1900, p. 203, PI. XXXIII, fig. 208. Dioecious, nannandrous ; oogonia single, subglobose, pore superior ; oospore globose, almost filling the oogonium ; epispore with subulate spines ; suffultory cell similar to other veg. cells ; dwarf males curved, on the suffultory cell, stipe not seldom 2-4-celled ; antheridium exterior i- (or more- ?) celled. veg. cell, 9-11 M diam., 4-10 diam. long, oog., 29-33 M " 32-35 /"• long, oos., 26-29 fj. " 26-29 M " lower cell, nau. stipe, 7-8 M " 20-24 M " upper cell, nan. stipe, 4.5-6 ^ " 21-30 /* " anth. cell, 5-6 M " 7-8 n " So. America. This species and the following, Oe. echinatum, are notably smaller than our other species with spinous spores ; Oc. echina- tum is larger than Oc. armigenim, with more spherical oogonia and oospores ; the spines are, moreover, rather conical than aculeate. The only reason for including Oe. annigcncm here is 252 TUFTS COLLEGE STUDIES, VOL. II, No. 3 that the figures given by Wolle for Oe. echinatum seem to Hirn to be more like Oe. armigeruin, which was undescribed at the time Wolle's book was published, than like Oe. echinatum. They are much more complete than Wood's figures, but Wolle does not give the localit}7 of the plant from which they were made. 49. OE. ECHINATUM (Wood) Wittrock, iSySa, p. 137 ; Hirn, 1900, p. 204; Androgynia cchinata Wood, 1872, p. 198, PI. XVIII, fig. 3. Dioecious, nannandrous ; oogonia single, glo- bose, usually depressed, pore superior ; oospore same form as the oogonium, nearly filling it, epispore with narrowly conical spines ; dwarf males nearly straight, near the oogonia. veg. cell, 8-12 M diam., 6-14 diam. long. oog., 35-36 M " oos., 25-26 /j. " 25-26 fj. long. Pa. A quite imperfectly known species; see notes under Oe. arm igcrnm. 50. OE. STELLATUM Wittrock, 1870, p. 129 ; Wolle, 1887, p. 85, PI. LXXXIV, figs, i and 2; Hirn, 1900, p. 205, PI. XXXIV, fig. 210. Dioecious, nannandrous, gynandrosporous ; oogonia single or 2-3, oboviform-globose, pore superior ; oospore globose, about filling the oogouium, epispore with conical spines, arranged in 4-7 occasionally anastomosing spirals, sufful- tory cell hardly swollen ; androsporangia i-3-celled, generally subepigynous ; basal cell elongate, terminal cell slender, hya- line, obtuse ; dwarf males nearly straight, on the suffultory cells, antheridium exterior, i-2-celled. veg. cell, 15-35 M diam., 3-6 diam. long. oog., 51-64 /x " 56-70 M long. oos., 50-58 M " 50-58 M " andr. cell, 14-19 M " 13-20 M " nan. stipe, 11-13-" " 45'52 M " anth. cell, 6-9 /x " 8-13 M " Florida. Europe, Africa, Australia, So. America. From the previously noted species with spinous spores this is distinguished by the spiral arrangement of the spines, which are also stouter and relatively shorter than in the species before mentioned. These characters it shares with Oe. Donnellii, which is, however, a larger plant in every way. The great variation in the diameter of the vegetative cells in the same filament is a noticeable character of this species. THE GREEN ALGAE OF NORTH AMERICA 253 51. OE. DONNELLII Wolle, 1880, p. 48; 1887, p. 85, PL LXXXIV, figs. 3-6 ; Him, 1900, p. 206, PI. XXXIV, fig. 211. Dioecious, nannandrous, idioandrosporous ; oogonia single, rarely double, slightly swollen, oboviforra-globose, pore supe- rior ; oospore globose, not fully filling the oogonium ; epispore with conical spines, arranged in 5-7 occasionally anastomosing spirals ; suffultory cell not swollen ; androsporangia 4-io-celled ; dwarf males slightly curved, on the suffultory cell, rarely on the oogonium ; antheridium exterior, i-2-celled. veg. cell, 41-59 M diam., iK'3 diain. long. oog., 63-78^ " 70-93 M long. oos., 60-70,1' " 60-70/11. " andr. cell, 40-45 p- " 10-12 n " nan. stipe, 16-21 /x " 63-74^ " anth. cell, 14-15 M " 8-22 ^ " Florida. Hirn's examination of authentic specimens enabled him to correct and complete the descriptions and figures of Wolle. 52. OE. HUNTII Wood, 1869, p. 333 ; 1872, p. 198, PI. XVII, fig. 2; Wolle, 1887, p. 85, PI. LXXXIV, fig. 9; Him, 1900, p. 208, PI. XXXIV, fig. 213 ; P. B.-A., No. 1471. Dioe- cious, nannandrous ; oogouia single, subglobose or subobovi- form-globose, pore inferior ; oospore globose, not filling the oogonium, epispore with four raised spiral lines ; suffultory cell similar to other vegetative cells ; basal cell elongate, terminal cell tapering, produced into a long hyaline seta ; dwarf males nearly straight, on the suffultory cells ; antheridium exterior, i- (or 2-?) celled. veg. cell, 15-25 M diam., 2^-3^ diam. long, oog., 50-60 M " 52-60 Mong. oos., 38-42 M " 38-42 M " nan. stipe, n M " 52 /"• " anth. cell, 10 M " 30 ^ " Mass., Pa. Wood's record was long the only one for this species, which he found growing in his aquarium. Wolle merely condenses Wood's description, and Him copies it, and gives dimensions taken from Wood's figures. Its nearest relative seems to be Oe. spirale from Java, but in the latter the arrangement of the spirals is quite different. For occurrence in Mass., see Collins, igoSb, p. 57. 53. OE. SEXANGULARE Cleve in Wittrock, 1870, p. 131 ; Wolle, 1887, p. 82, PI. LXXIX, figs. 8 and 9 ; Him, 1900, p. 254 TUFTS COLLEGE STUDIES, VOL. II, No. 3 211, PI. XXXV, fig. 216; Wittr. and Nordst., Alg. Exsicc., No. 12. Dioecious, nannaiidrous, gynandrosporous ; oogonia single, rarely double, sexangular-ellipsoidal, having the great- est width and the pore slightly above the middle ; oospore same form as the oogonium, quite filling it, membrane smooth ; suffultory cell not or slightly swollen ; androsporangia 1-3- celled, dwarf males on suffultory cells, slightly curved ; stipe sometimes 2-3-celled ; antheridium exterior, unicellular. veg. cell, 9-16 ft diam., 3-7 diam. long. oog., 29-33 M " 33-39 M long. oos., 27-31 n " 31-36 M " andr. cell, 13-14 M " 10-14 M " nan. stipe, 7-9 /* " 21-30 //. " anth. cell, 6-7 /u " 9-12 M " Pa. Europe. Var. MAJUS Wille, 1880, p. 68; Hirn, 1900, p. 212, PI. XXXV, fig. 217; P. B.-A., No. 522. Larger, oogonia most swollen at the middle, pore median. veg. cell, 15-23 M diaui., 2-3 diam. long. oog., 36-42 M " 4!-45 /* long. oos., 34-40 n " 39-43 M " andr. cell, 14-18 /x " 8-10 M " nan. stipe, 7-9 M " 18-30 M " anth. cell, 6-8 /* " 6.5-10 /* " Mass. Europe. The form of the oogonium easily distinguishes this from all other species, American or foreign. 54. OE. HYSTRIX Wittrock, 1870, p. 133 ; Wolle, 1887, p. 87, PI. LXXXIV, fig. 8; Him, 1900, p. 213, PI. XXXV, fig. 218. Dioecious, nannandrous, gyuandrosporous (or possibly idioandrosporous); oogonia single, ellipsoid, pore median; oospore ellipsoid, nearly filling the oogonium, covered with sub- ulate spines ; suffultory cell little or not swollen ; androspor- angia i-3-celled, terminal cell obtuse ; dwarf males slightly curved, on the suffultory cell ; antheridium exterior, unicellular, veg. cell, 17-28 M diam., i%-4/^ diatn. long, oog., 38-48 M " 45-65 M long, oos., 37-46 M " 43-55 M " andr. cell, 17-18 M " 13-18 /u " nan. stipe, 10-11 M " 22-25 M " anth. cell, 6-8 M " 9-14 M " Pa. Europe. Distinguished from all other spinous species by the elongate spines and the very short dwarf males. THE GREEN ALGAE OF NORTH AMERICA 255 55. OE. CRASSIUSCULUM var. IDIOANDROSPORUM Wittr. and Norclst., Alg. Exsicc., Nos. 208, 310; Wolle, 1887, p. 80, PL LXXVII, figs. 14-19; Him, 1900, p. 215, PI. XXXV, fig. 220; P. B.-A., Nos. 72, 716. Dioecious, nannandrous, idioan- drosporous ; oogonia single or 2, globose-oboviform to globose ; oogonia ellipsoid-globose to angular-oboviform or angular-glo- bose, nearly filling the oogonium ; pore superior; membrane smooth, thick ; suffultory cell similar to the other vegetative cells; androsporangia 2-5-celled ; dwarf males nearly straight, on or near the suffultory cell ; antheridium exterior, i- (or more- ?) celled. veg. cell, 25-36 /a diam., 2)^-5^ diam. long, oog., 48-59^ " 57-9° Mlong. oos., 42-57 M " 50-66 M " andr. cell, 30-34 /a " 12-21 /x " nan. stipe, 14-16 /x " 60-70 /x " anth. cell, 8-10 /x " 10-18 /x " Me., Mass., Conn., N. Y., N. J., Pa., Minn., So. Dakota. Northern Europe. The type, occurring in northern Europe, is gynandrosporous, and never has the angular oospores. The plants from Maine and Mass., distributed under No. 72, P. B.-A., have the oospores and oogonia broader and more globose, often 4 in a •series ; the androsporangia are more slender. From the three following species, resembling it in many particulars, Oe. crassi- iisadum in all its forms can be distinguished by the unswollen suffultor)- cell ; the unusually thick membrane is also to be noted. 56. OE. BORISIANUM (Led.) Wittrock, 1870, p. 132; Wolle, 1887, p. 81, PI. LXXVIII, figs. 6-9; Him, 1900, p. 217, PI. XXXVI, fig. 223; P. B.-A., No. 517. Dioecious, nannaudrous, gyuaudrosporous or idioandrosporous ; oogonia single, or rarely 2-3, oboviform or quadrangular-ellipsoid, pore superior; oospore ellipsoid or oboviform, sometimes quadrangu- lar-ellipsoid, not quite filling the oogonium, membrane smooth ; suffultory cell swollen ; androsporangia i-7-celled, in the upper part of the filament, often subepigynous ; basal cell elongate; terminal cell, which may be an oogonium, short-apiculate or obtuse, or sometimes produced in a long, hyaline seta ; dwarf males slightly curved, on suffultory cell ; antheridium exterior, i-2-celled. 256 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, suf. cell, oog., oos., andr. cell, nail, stipe, anth. cell, Mass., Pa., Cal. A common species !5-23 M diam., 31-38 /* " 40-50 M " 35-46 AI " 16-19 M " 12-15 /" " 3-6 diatu. long. " M long. 55-90 48-60 tt " 15-23 /x " 35'47 -" " 7-10 M " 11-15 M " Europe, Australia, So. America. distinguished from Oe. crassiusculum by the much swollen cell below the oogonium ; the cells are rela- tively slender just above the oogonium, and increase rapidly and uniformly to and including the oogonium ; above this the cell is slender again ; from the two following species, Oe. Wolle- anum and Oe. concatcnatum, it is distinguished by the oospore being smooth, not striate. 57. OE. WOLLEANUM Wittrock, 18783, p. 137 ; Wolle, 1887, p. 82, PI. L,XXX, figs. 4 and 5 ; Him, 1900, p. 220, PI. XXXVII, fig. 226 ; Wittr. and Nordst., Alg. Exsicc., No. 107. Dioecious, nannandrous, gynandrosporous or idioandrosporous ; oogonia single or 2, more rarely 3-4, suboboviform or quadran- gular-ellipsoid, pore superior, membrane with raised longitud- inal lines on the inner surface ; oospore same form as the oogo- nium, quite filling it, membrane double ; external membrane with 25-35 longitudinal raised lines, rarely anastomosing ; inner membrane smooth ; suffultory cell swollen ; androsporangia 1-3- celled, often subepigynous, or scattered in the upper part of the filament ; basal cell elongate ; terminal cell, which is some- times an oogonium, short acute or acuminate ; dwarf males on suffultory cell, stipe slightly curved ; antheridium exterior, 1-3- celled. veg. cell, suf. cell, oog., oos., andr. cell, nan. stipe, anth. cell, Greenland, Mass 21-30 fj. diam. 45-56 M " 58-68 fj. " 56-66^ " 21-30/4 " 15-24 /x " 9-14 M " 3-8 diaui. long. ^-2 long. 69-89 65-83 M " 18-25 M " 54-60/1* " 7-11 M " Conn., N. J., Pa., Minn., Fla. Europe, Asia, So. America. A cosmopolitan species, and generally quite uniform in its characters; it is distinguished from Oc. Bonsiamim and Oe. con- catcnatum by the lines on the oogonium and the oospore, the two fitting closely, the elevations on one into the furrows in THE GREEN AL.GAE OF NORTH AMERICA 257 the other ; Oc. Borisianum has smooth spores ; Oe. concatcnatum has dotted lines on the median membrane of the oospore, but the outer membrane and the oogonium are smooth. One form and one variety are to be noticed. Forma INSIGNE (Nordstedt) Hirn, 1900, p. 222, PI. XXXVII, fig. 227. Stouter, lines on the oospore and oogonium 35-40, oogonia i-io, androsporangia to lo-celled, antheridia i-4-celled. The dimensions are one-fourth or one-fifth larger in all parts than in the typical form. N. J. Sweden. Var. CONCINNUM Hirn, 1900, p. 222, PL XXXVII, fig. 228. Smaller ; oospore not quite filling the oogonium ; lines on the membrane of the oospore finely crenulate. The dimensions are about one-tenth smaller than in the type. Minn. 58. OE. CONCATENATUM (Hass.) Wittrock, 1874, p. 25 ; Wolle, 1887, p. Si, PI. LXXIX, figs. 1-3, and var. sctigerum Wolle, 1887, p. 82, PL LXXIX , figs. 4 and 5 ; Hirn, 1900, p. 223, PL XXXVIII, fig. 330. Dioecious, nannandrous, gynan- drosporous ; oogonia single or 2-6, suboviform or quadrangular- ellipsoid, pore superior ; oospore same form as the oogonium, nearly filling it, membrane apparently triple ; outer membrane smooth, median membrane with pits, more or less distinctly ar- ranged in 30-35 longitudinal series, inner membrane smooth ; suffultory cell swollen; androsporangia i-4-celled; basal cell elongate, terminal cell obtuse ; dwarf males curved, on sufful- tory cell ; antheridium exterior, i-4-celled. veg. cell, 25-40 fj. diam., 3-10 diam. long, suf. cell, 50-62 p. " i^-2>4 " oog., 63-83 fj. " 76-105 M long, oos., 60-76 /j. " 67-95 fj, " andr. cell, 25-28 fj. •' 15-36 fj- " nan. stipe, 17-25-" " 5°-75 M " anth. cell, J3-T5 M " 12-25 M " Mass., N. J., Pa., Alaska. Europe. Various forms of this species are found in Europe, but only the type has been recorded in this country. The distinctions between this species and the three preceding have been already indicated. 59. OE. MULTISPORUM Wood, 1869, p. 141 ; Wolle, 1887, p. 78, PL LXXX, figs. 6 and 7 ; Hirn, 1900, p. 232, PL XXXIX, fig. 239. Dioecious, nannandrous ; oogonia single or 2-3, sub- oviform or subglobose (pore superior ?) ; oospore globose, nearly 258 TUFTS COLLEGE STUDIES, VOL. II, No. 3 filling the oogonium (membrane smooth ?) ; (suffultory cell of same form as the other vegetative cells ?) ; dwarf males slightly curved, near the oogonium ; antheridium exterior, i- (or more-?) celled. veg. cell, 12-14 M diam., \~%.-\^ diatn. long. oog., 31-35 M " 28-33 M long. OOS., 27-29 M " 25-29 /"• " nan. stipe, n M " 26 /u " anth. cell, 7-9 M " 9 /" " Pa. The description is incomplete, but is all that can be obtained from Wood's figures and text ; no original specimens are known. 60. OE. MACRANDRIUM Wittrock, 1870, p. 130, PI. I, figs. 3-5 ; Wolle, 1887, p. 80, PI. LXXXII, figs. 1-3 ; Him, 1900, p. 233, PI. XXXIX, fig. 240; Wittr. and Nordst., Alg. Ex- sicc., Nos. 108, 505, 1217. Dioecious, nannandrous ; oogonia single or 2-3, rarely 4 ; globose-oboviform, operculate, division superior ; oospore globose, more rarely oboviform-globose, not fully filling the oogonium, membrane smooth ; suffultory cell of same form as the other vegetative cells ; terminal cell obtuse or very shortly apiculate ; dwarf males on or near the oogonium, stipe much curved, sometimes 2-3-celled ; antheridia i-7-celled. veg. cell, 15-20 M diam., 3-5 diam. long, oog., 36-42 M " 43-54 M long, oos., 31-37 M " 33-39 M " nan. stipe, 12-13 M " 24-33 M " anth. cell, 9-10 /j. " 7-10 M " Mass., Pa. Europe. Var. AEMULANS Hirn, 1900, p. 235, PI. XXXIX, fig. 242 ; Oe. Lundense Wolle, 1887, p. 79, PI. LXXVII, figs. 9 and 10 ; Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 1402. Some- what smaller in all dimensions, as well as more variable ; oogonia 2-6. Pa., Cal. So. America. From similar American species this is distinguished by the manner in which the operculum separates from the lower part of the oogonium ; the parts are not parallel, but more as if hinged at one side and open at the other. 61. OE. LONGATUM Kiitzing, 1853, p. n, PI. XXXIII, fig. 6; Wolle, 1887, p. 95, PI. LXXV, fig. 3; Hirn, 1900, p. 239, PI. XL,, fig. 248; P. B.-A., No. 812. Dioecious, nannandrous; THE GREEN ALGAE OF NORTH AMERICA 259 oogonia single or 2, more rarely 3, oviform or ellipsoid, oper- culate, division superior; oospore ellipsoid, about filling the oogonium, membrane sometimes very finely crenulate ; sufful- tory cell similar to other vegetative cells ; basal cell elongate, terminal cell obtuse ; dwarf males on the oogonium ; anther- idium exterior, i- (or more-) celled, curved. veg. cell, 4-7 fj- diam., 2-5 diam. long. oog., 16-18 M " 21-25 ,u long. oos., 15-17 M " 17-19 M " nan. stipe, 5-6 M " 10-15 M " anth. cell, 4-5 M " 5-6 M " Mass., Pa. Europe. A very slender species, usually found as scattered filaments among other species of Oedogoninm. The curved antheridia seem peculiar among the American species. 62. OE. ACROSPORUM De Bary, 1854, pp. 47, 60, 94, PI. Ill, figs. 1-12; Him, 1900, p. 244, PI. XLI, fig. 254; Oc. acro- sporum var. connectens P. B.-A., No. 409. Dioecious, nannan- drous, gynandrosporous (or idioandrosporous) ; oogonia single, terminal, ellipsoid, operculate, division near summit, operculum minute, deciduous ; membrane of oogonium with longitudinal, sometimes anastomosing ridges on the inner surface ; oospore quite filling the oogonium, the outer membrane with 23-30 longitudinal, very finely crenulate ridges, closely fitting between the ridges of the oogonium, and connected by delicate trans- verse striae ; inner membrane smooth ; suffultory cell somewhat swollen ; basal cell elongate, terminal cell obtuse ; androspor- angia i-2-celled, hypogynous ; dwarf males curved, on the suf- fultory cell, stipe sometimes 2-3-celled, upper cells long, antheridium exterior, i-2-celled. veg. cell, 13-21 fj. diam., 3-6 diatu. long. suf. cell, 17-25-" " i #-3 oog., 38-48 n " 50-63 M long, andr. cell, 16-21 M " 12-15 /" " lower cell, nan. stipe, 9-12 ^ " 30-38 M " upper cell, nan. stipe, 6-8 M " 55-?i i" anth. cell, 6-8 fj. " 9-15 M " Mass. Europe, Asia, So. America. Our only species of Ocdogonium in which each fertile filament bears one terminal oogonium, and none elsewhere. Forma BOREALE (Wolle) Him, 1900, p. 245, PI. XLI, fig. 256 ; Oe. acrosporum var. borealc Wolle, 1887, p. 84,- PI. LXXIX, 260 TUFTS COLLEGE STUDIES, VOL. II, No. 3 figs. 10 and u. Filaments of few cells, vegetative cells shorter than in the type, 14-16 ^ diam., 3-5 diam. long. N. J., Pa. Probably a local form. Var. FLORIDENSE Wolle, 1887, p. 83, PI. LXXXV, figs, i and 2; Him, 1900, p. 246, PI. XLJ, fig. 258. A slender form, with long vegetative cells, suffultory cells more swollen than in the type ; dwarf males very long, stipe 2-3-celled. veg. cell, 7-8 M diam., 5-11 diain. long, oog., 33-35 M " 45-50 M diam. Florida. Var. BATHMIDOSPORUM (Nordst.) Him, 1900, p. 246, PI. XLJI, fig. 259; Oe. acrosporum, P. B.-A., No. 163. Smaller, with fewer ridges on oogonium and oospore, about 11-17, dis- tinctly crenate, with distinct striae between ; stipe of dwarf male unicellular. veg. cell, 12-17 /"• diam., 3-8- diam. long, suf. cell, 15-22 M " 2/2-5 oog., 30-40,0. " 40-54 M long, nan. stipe, 9-11 M " 9-12 M " ANTHERIDIUM INTERIUS, PORIFERA, ELLIPSOSPORA. 63. OE. CYATHIGERUM Wittrock, 1870, p. 131, PI. I, figs. 6 and 7 ; Hirn, 1900, p. 252, PL XLJII, fig. 265. Dioecious, nannandrous, idioandrosporous ; oogonia single or 2-3, subovi- form or quadrangular-ellipsoid, pore superior ; oospore same form as the oogonium, filling it, membrane triple ; outer mem- brane smooth, median membrane with 16-25 longitudinal, continuous, rarely anastomosing, often curved, ridges, inner membrane smooth ; basal cell elongate, terminal cell, which sometimes is an oogonium, obtuse ; dwarf males goblet-shaped, curved, on the suffultory cell, rarely on the oogonium ; anther- idium interior. veg. cell, 21-30 M diani., 2-10 diam. long, suf. cell, 42-48 M " i-V2,'< " oog., 57-66,1* " 70-100 fj. long, oos., 51-62 ^ " 60-75 M " anth. cell, 23-30 /j. " 12-30 M " nan. cell, 12-15 M " 50-58 M " The type is European, and has not yet been found in this country. We have Forma ORNATUM (Wittrock) Hirn, 1900, p. 254, PI. XLJII, THE GREEN ALGAE OF NORTH AMERICA 261 fig. 267 ; with longer dwarf males, 60-75 p., and slightly longer oospores ; otherwise like the type. Mexico. Forma AMERICANUM Wolle, 1887, p. 77, PI. LXXXI, figs. 20-22 ; Hirn, 1900, p. 256. More slender than the type, with shorter vegetative cells, and dwarf males on the oogonium, not on the sufftiltory cell. veg. cell, 17-21 Aidiam., i/£-j cliam. long. oog., 45-50 /j. " 55-63 M long. oos., 39-40 M " 44-46 /j. " nan. cell, 12-15 /"• " 5<>54 M " Pa. The long, goblet- like dwarf males are characteristic of this species, and have given it its specific name. The interior antheridium is often hard to distinguish, and the species was at first described as having unicellular antheridia. The dwarf males, with the much swollen suffultoty cells, and the irregular lines on the oospore, make a combination of characters that clearly distinguishes the species, and this combination is found in all the forms and varieties. ANTHERIDIUM INTERIUS, OPERCULATA. 64. .OE. TNDULATUM (Breb.) A. Braun in De Bary, 1854., p. 94; Wolle, 1887, p. 76, PI. LXXVII, fig. 8; Hirn, 1900, p. 257, PI. XLV, fig. 273; Wittr. and Nordst., Alg. Exsicc., No. 702, in part. Dioecious, nannandrous, gynandrosporous or idioandrosporous ; oogonia single or 2, subglobose or ellipsoid- globose, operculate, division inferior, oospore globose or sub- globose, almost filling the oogonium, membrane smooth, gener- ally thick ; suffultory cell not or only slightly swollen ; andro- sporangia to 7-celled ; vegetative cells four times undulate- constricted ; basal cell elongate, not undulate ; terminal cell, which sometimes is an oogonium, obtuse ; dwarf males elongate- obconic, generally on the suffultory cell, more rarely on other vegetative cells near the oogonium ; antheridium interior. veg. cell, 12-22 /x diaui., 3-5 diam. long. oog., 48-56 M " 50-75 M long. oos., 42-50 M " 42-52 M " andr. cell, 15-21 n " 7-14 n " nan. cell, S-io M " 48-65 /j. " Europe, Australia, So. America. Reported by Wolle, but the only definite American locality recorded is Martha's Vineyard, Mass., and the plant there is 262 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Forma SENEGALENSE (Nordst.) Hirn, 1900, p. 261, PI. XLV, fig. 277 ; P. B.-A., No. 73. Oogonia and oospores somewhat smaller than in the type, dwarf males shorter ; oogonia to 5- seriate ; vegetative cells with the three median swellings repand, the terminal swellings entire. veg. cell, 15-22 M diatu., 3-5 diaui. long, oog., 42-52 M " 44-63 M long, oos., 3 7-44 M " 36-44 M " andr. cell, 15-19 M " 9-18 M " nan. cell, 6-8 M " 37-44 /j. " ]\Iass. Africa. The description and the measurements just given are founded on the specimens distributed in P. B.-A., No. 73; the original forma scnegalense from Africa, has oogonia not over 3-seriate, and swellings of the vegetative cells entire. As with Oc. cyathi- gcruin, so in this species the antheridia appear to be unicellular unless good material is carefully examined. The peculiar form of the vegetative cells easily distinguishes it from all our other species, Oc. nodulosnm being the only other with similar con- strictions, but there is no danger of confounding the two, if the constrictions are counted ; these two are our only species which are recognizable even when sterile. NANNANDRES UNICELLULARES ; OPERCULATA, GLOBOSPORA. 65. OE. ROTHII (LeCl.) Pringsheim, 1858, p. 69, PI. V, fig. 4 ; Him, 1900, p. 265, PI. XL/V7, fig. 282 ; P. B.-A., No. 520. Dioecious, nannandrous, gynandrosporous ; oogonia single or 2-3-seriate, subdepressed-globose, operculate, division median, narrow ; oospore depressed-globose, almost filling the oogonium, membrane smooth ; suffultory cell not swollen ; androsporangia i-4-celled, s'ubhypogynous, hypogynous, subepigynous or scat- tered ; dwarf males oboviform, unicellular, on the oogonium. veg. cell, 6-io/xdiaui., 3-8 diam. long, oog., 20-27 fj. " 16-27 M l°ng- OOS., 17-25 fJ. " 14-20 fJL " andr. cell, 6-8 M " 5-10/1 " nan. cell, 4 /u, " 11-12 M " Mass. /-'./trope. 66. OE. DECIPIENS Wittrock, 1874, p. 18 ; Wolle, 1887, p. 75, PI. LXXVII, figs. 5 and 6; Hirn, 1900, p, 266, PL XLVI, fig. 283; Wittr. and Nordst., Alg. Exsicc., No. 602, in part. Dioecious, nannandrous, gynandrosporous ; oogonia single, or THE GREEN ALGAE OF NORTH AMERICA 263 2-3, subdepressed-globose, operculate, division median, rather narrow ; oospore subdepressed or depressed-globose, almost fill- ing the oogonium, membrane smooth ; suffultory cell not swollen ; androsporangia to 6-celled, subepigynons, hypogy- nous or scattered ; dwarf males oboviform, unicellnlar, on the oogoninm. veg. cell, 9-12 n diatn., 3-5 diam. long, oog., 30-38 p. " 27-40 M long, oos., 25-34 n " 23-28 M " andr. cell, 9-10 p. " 8-15 p. " uan. cell, 6-7 M " 13-15 M " N. J., Iowa. Europe. Somewhat resembling Oe. Rothii, but a larger plant. 67. OE. ARESCHOUGII Wittrock, 1870, p. 122, PI. I, figs, i and 2 ; Wolle, 1887, p. 76, PI. LXXVII, fig. 7 ; Him, 1900, p. 270, PI. XlyVI, fig. 289. Dioecious, nannaudrous, gynandro- sporous ; oogonia 2-6 or single, subdepressed- or depressed- pyriform- globose, operculate, division median, broad ; oospore globose, rarely subdepressed-globose, not nearly filling the oogonium, membrane smooth ; suffultory cell of the same form as the other vegetative cells; androsporaugia i-6-celled, sub- epigynous or hypogynous, or more rarely scattered ; vegetative cells capitellate ; basal cell elongate, terminal cell, which some- times is an oogonium, obtuse; dwarf males oboviform, unicel- lular, on the oogonium. veg. cell, 8-13 M diam., 4-6 diam. long, oog., 34-39-" " 36-4o M long, oos., 22-26 fj. " 22-25 M " andr. cell, 9-11 /* " 10-12 /u, " nan. cell, 6-7 //. " 13-15 /u. " Greenland, N. J. Europe, So. America. Forma ROBUSTUM Hirn, 1900, p. 271, PI. XL,VI, fig. 290. Idioandrosporous ; larger in all parts than the type, especially as to the vegetative cells ; oogonia to 8-seriate. veg. cell, 12-17 M diam., 3-6 diam. long, oog., 36-40 /x " 36-53 p. long. OOS., 30-32 M " 27-31 ju. " andr. cell, 9-12 p. " 10-13 f- " nan. cell, 6-8 /*, " 14-15 M " England. Hirn includes provisionally under this form the plant from Minnesota, distributed in Tilden, American Algae, No. 3, as 264 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Oe. obtnincatum var. oblatum Tilden, though the dimensions vary somewhat, being veg. cell, 15-20 /j. diani., 1/4-2)4 diatn. long. oog., 37-4- M " 35-38 Along. 68. OE. PLATYGYNUM Wittrock, i872a, p. i ; Wolle, 1887, p. 75, PL LXXVII, figs. 1-4; Him, 1900, p. 276, PI. XLVII, fig. 301 ; Wittr., Nordst. and L,agerh., Alg. Exsicc., No. 1218. Dioecious, nannandrous, gynandrosporous and idioandrospor- ous ; oogonia single or very rarely 2, depressed-oboviform, with 7-12 rounded prominences arranged in a whorl around the middle, operculate, division inferior ; oospore depressed- or subde- pressed-globose, not quite filling the oogonium, membrane smooth ; suffultory cell not or slightly swollen ; androsporangia 1-3 celled ; vegetative cells slightly capitellate, terminal cell obtuse ; dwarf males unicellular, oboviform, very small, on the oogonium. veg. cell, 6-10 /j. diam., 2-5 diatn. long, oog., 21-30 /j. 16-24 A4 long, oos., 17-24 M " 15-20 n " andr. cell, 6-8 ^ " 7-8 ^ "' nan. cell, 4.5-5 P. " 8.5-9.5 M " X. J., Pa., Fla., Minn. Europe, So. America. The peculiar form of the oogonium, with the whorl of projec- tions, is not found in any other American species. 69. OE. PLUVIALE Nordstedt in Rabeuhorst, Algen., No. 2257 ; Him, 1900, p. 280, PI. XLVIII, fig. 311 ; P. B.-A., No. 1190. Oe. fonticola Wolle, 1887, p. 93, PI. IVXXV, figs. 4-6. Dioecious, nannandrous, idioandrosporous ; oogonia single, very rarely 2-3, oboviforrn-globose or subglobose, operculate, divi- sion superior ; oospore subglobose or subellipsoid-globose, almost rilling the oogonium, membrane smooth ; suffultory cell not swollen ; vegetative cells varying much in diameter in the same individual ; basal cell elongate, terminal cell obtuse ; androsporangial plants often somewhat more slender than the female ; androsporangia to lo-celled ; dwarf males broadly oboviform, unicellular, on the oogonium. veg. cell, female, 22-29 V- diam., 54-2 diam. long, veg. cell, male, 18-27 ^ " 1-2 " oog., 34-45 M " 34-50 M long, oos., 32-40 M " 3!-43M " aiidr. cell, 17-25 ^ " 6-13 /j. " nan. cell, 10 n " l4-*5 M " Cal. Europe. THE GREEN ALGAE OF NORTH AMERICA 265 Wolle says frequent, but gives no definite locality. The con- siderable variation both in length and diameter of cells in the same plant, is quite noticeable. SPECIES OF WHICH THE ORGANS OF FRUCTIFICATION ARE ONLY PARTLY KNOWN. 70. OE. GIGANTEUM Kiitzing, 1845, p. 200; Wolle, 1887, p. 94, PI. LXXVI, figs. 1-6 ; Him, 1900, p. 295, PL XXIII, fig. 115; Phyk. Univ., No. 177. Oogonia single, slightly swollen, cylindric-oboviform, pore superior ; oospore cylindric-ellipsoid or subellipsoid, nearly filling the oogonium, membrane appar- ently triple; outer membrane smooth, median with 25-30 longi- tudinal series of pits ; inner membrane smooth ; suffultory cell often larger than the other vegetative cells, but not swollen. veg. cell, 30-50 fi diam., z-4/4 diam. long, suf. cell, 40-60 /j. " i>£-3>£ " oog., 53-69 M " 67-106 /x long, oos., 51-65 M " 65-103 /j. " Mentioned by Wolle, but without exact locality ; we have no other species with similar markings to the spore. 71. OE. PYRIFORME Wittrock, 1874, p. 39; Wolle, 1887, p. 95, PI. IvXXVII, figs. 11-13; Him, 1900, p. 303, PI. XXV, fig. 137. Oogonia single, pyriform, operculate ; antheridia 2-3- celled, subepigynous, hypogynous or scattered. veg. cell, 13-16 M diam., 3/^-6 diam. long, oog., 40-45 fj. " 54-60 M long. ?anth. cell, 10-12 n " 9-12 /* " N. J. Australia. A very imperfectly known species ; but the form of the oogonium is peculiar; pyriform, or perhaps better, "top- shaped." 72. OE. SANCTI THOMAE Wittrock and Cleve in Wittrock, 1874, p. 40; Him, 1900, p. 304, PI. XXIX, fig. 173. Oogonia single or 2-3, pyriform, operculate, division superior; oospore pyriform-oboviform, not quite filling the oogonium, membrane smooth ; basal cell subhemispherical, not elongate ; terminal cell very slender, subhyaline. veg. cell, 7-15 M diam., 2-6 diam. long, term, cell, 2-4 M " 5-7 " oog., 28-33 M " 36-50 M long, oos., 25-30 /x " 28-35 M " basal cell, 14-23 AC " 8-12 /j. " St. Thomas, W. I. 266 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Somewhat resembling Oe. pyri forme, but a smaller plant, and with peculiar basal and terminal cells. 73. OE. CATARACTUM Wolle, 1887, p. 77, PI. L,XXXV, figs. 10-12 ; Hirn, 1900, p. 308, PI. XI^II, fig. 264. Dioecious, nannandrous, idioandrosporous ; oogonia single or 2, often ter- minal, oboviform-globose, subglobose or broadly ovate, pore superior ; oospore globose or oboviform-globose, almost filling the oogonium ; androsporangia 2-6-celled, dwarf males much curved., on suffultory cell or sometimes on the cell below this ; antheridium interior ? veg. cell, 28-38 /u diatn., J^-3 diatu. long. oog., 55-6° /* " 60-75 M long. oos., 50-55 M " 50-60 M " andr. cell, 26-30 M " 10-15 M " nan. cell, 10 M " 65 /* " Pa. Although this description appears to be fairly complete, the species is placed by Hirn among those insufficiently known, as Wolle's statements in regard to the male plant are contradictory ; this being given as unicellular and also as having internal an- theridia. Hirn suggests that it may be a form of Oe. crassius- culum. 74. OE. LONDINENSE Wittrock, 1874, p. 39; Wolle, 1887, p. 94, PI. L,XXV, figs. 7 and 8 ; Hirn, 1900, p. 317. Oogonia 2 or i, globose, division median, oospore globose, almost filling the oogonium ; antheridia (or androsporangia ?) i-2-celled, hy- pogynous. veg. cell, 10-15 M diani., !/^-5 diarn. long, oog., 33-35 M " 33-43 M long. OOS., 27-32 H " 27-32 M " anth. cell? 12 /u. " 10-11 M " N. J., according to Wolle. A very imperfectly known species, and American only with some doubt, there being no other record than Wolle's. 2. BULBOCHAETE Agardh, 1817, p. XXIX. Filaments branching ; vegetative cells increasing in size to upper end ; basal cell often lobed, attached to substratum ; ter- minal cell of each filament and branch produced into a long, hyaline seta with a bulbous base ; plant increasing mostly by division of the basal cell of the principal filament or of a branch ; oogonia arising by a double division of a vegetative cell. THE GREEN ALGAE OF NORTH AMERICA 267 There is no danger of mistaking a Bulbochacte, even in the sterile condition, for any other alga ; the erect, branching frond, with cells larger at their top than at their bottom, and every branch ending in a long seta with a bulbous base, are unmis- takable characters. In the determination of species much the same distinctions are used as in Oedogonium, and also charac- ters drawn from the formation of the oogonium ; as this arises by a double division of the vegetative cell, the suffultory cells are two, and according as the upper of the two is longer or shorter than the lower, or of the same length, we have the char- acters, dissepiment inferior, superior or median. If the two partition walls have formed directly across the axis of the orig- inal cell, we have oogonium erect ; if one of them is oblique, giving one of the cells a five-angled appearance in section, we have oogonium patent. The species of Bulbochacte are found in the same stations as Oedogonium, and though not so common as species of the latter, they are by no means infrequent, and are distributed all over the world. KEY TO THE SPECIES OF BULBOCHAETE. i. Spores globose. 2. i. Spores ellipsoid. 10. • 2. Oogonia erect. i. B. Brebissonii. 2. Oogonia patent. 3. 3. Oogonia 60 /u diam. or more. 4. 3. Oogonia not over 56 jj. diam. . 5. 4. Gynandrosporous. 8. B. setigera. 4. Idioaudrosporous. 18. 5. Oogouiuni biconic- or subquadraugular-globose. 7. B. angulosa. 5. Oogonium depressed- or subdepressed-globose. 6. 6. Dissepiment of suffultory cell about median. 7. 6. Dissepiment of suffultory cell superior. 8. 7. Membrane of oospore minutely crenulate. 2. B. intermedia. 7. Membrane of oospore strongly crenulate. 3. B. crcnnlata. 8. Oogouia 44-56 /j. diam . 6. B.dispar. . 8. Oogonia rarely equalling 46 //. q. 9. Gynandrosporous. 4. B. Nordstedtii. 9. Idioaudrosporous. 5. B . polyandria. 10. Monoecious. \\. 10. Dioecious. 13. 268 TUFTS COLLEGE STUDIES, VOL. II, No. 3 ii. Vegetative cells about as long as broad, moniliform. ii. B. monile. ii. Vegetative cells longer than broad, subcylindrical. 12. 12. Oogonium 20-25 M diam. 12. B. nana. 12. Oogonium 26-35 M diam. 13. B. niirabilis. 13. Suffultory cell without dissepiment. 14. B.pygmaea. 13. Suffultory cell with dissepiment. 14. 14. Oogonium about ij£ times as long as broad. 15. 14. Oogonium about i^ times as long as broad or more. 19. B. minor. 15. Oogonium 26-39 f- diain. 16. 15. Oogonium 44-60 /u diam. 18. B '. insignis. 16. Vegetative cells repand. 17. B. repanda. 16. Vegetative cells cylindrical. 17. 17. Cells rectangular in longitudinal section. 16. B. rectaiignlaris. 17. Cells oval or subtriangular in longitudinal section. 15. B. variansf. sub simp lex. 18. Dwarf males shorter than the oogonium. 9. B. crassiuscnla. 18. Dwarf males longer than the oogonium. 10. B.gigantea. GLOBOSPORAE. 1. B. BREBISSONII Kiitzing, 1855, p. 19, PI. L/XXXVI.B ; Hirn, 1900, p. 323, PI. LJ, fig. 330; Rabenhorst, Algen, No. 1055. Dioecious, nannandrous, gynandrosporous ; oogonia depressed-subquadrangular-globose, erect, below terminal setae or androsporangia ; dissepiment of suffultory cell very low ; epispore of oospore scrobiculate ; androsporangia scattered or epigyuous, i-3-celled ; dwarf males on oogonia, more rarely near them, antheridium interior, stipe slightly curved, shorter than the antheridium. veg. cell, 17-20 fj. diam., 3-4^ diam. long. oog., 42-50 M " 37-45 M long, andr. cell, 11-15 M " 12-18 /x " nan., 10-12 M " 28-33 <" " Mass., Alaska. Northern Europe. The only species with interior antheridium and erect oogonia. 2. B. INTERMEDIA De Bary, 1854, p. 72, PI. IV, figs. 1-7 ; \Volle, 1887, p. 97, PI. lyXXXVI, figs. 1-3 ; Hirn, 1900, p. 326, PI. LJI, fig. 333 ; P. B.-A., No. 973. Dioecious, nannan- drous, gynandrosporous ; oogonia sub-depressed-globose, pat- ent, below the androsporangia ; dissepiment of suffultory cells about median ; epispore of oospore pitted or more rarely smooth- ish ; androsporangia i-, rarely 2-celled, epigynous, more rarely scattered ; dwarf males on oogonium ; antheridium interior, stipe slightly curved, shorter than the antheridium. Fig. 82. THE GREEN ALGAE OF NORTH AMERICA 269 veg. cell, 17-20 fji diam. 2-3 '< diam. long. oog., 40-48 fj. " 31-40 M long. andr. cell, 11-13 M " 7-12 M " nan., 9-10 /j. " 21-26 /j. " Greenland, Conn., Pa., Alaska. Europe, Australia. Forma SUPRAMEDIANA (Wittr.) Him, 1900, p. 328, PI. LIT, %• 335 ; Wittr. and Nordst., Alg. Exsicc., No. 509, in part. Oogonia smaller, usually below the terminal setae ; dissepiment of suffultory cells somewhat above the middle, rarely quite near the middle ; androsporangia scattered. veg. cell, 17-20 M diam., 2-3 diam. long. oog., 40-45 M " 32-37 M long. anth. cell, 11-12 /x " 7-11 M " nan., 9-10 M " 20-25 /"• " Pa. A common species and variable ; the plants distributed as P. B.-A., No. 973, have vegetative cells and oogonia .somewhat more slender than in the type. 3. B. CRENULATA Pringsheini, 1858, p. 72, PI. VI, fig. 4; Wolle, 1887, p. 97, PI. I.XXXVI, fig. 4; Him, 1900, p. 331, PI. LIII, fig. 337. Wittr. and Nordst., Alg. Exsicc., No. 602, in part. Dioecious, nannandrous, gynandrosporous ; oogonia subdepressed-globose, patent, below the terminal setae or the androsporangia, rarely under vegetative cells ; dissepiment of suffultory cells usually median or slightly lower ; epispore of oospore distinctly pitted ; androsporangia epigynous or scat- tered, i-5-celled ; dwarf males on oogonium or near it, antherid- ium interior, stipe slightly curved, shorter than the antheridium. veg. cell, 16-20 M diam., 2-3^ diam. long. oog., 43-48 n " 35-43 n long. anth. cell, 10-15 /j. " 7-10 /j. " nan., 9-10 M " 24-26 .a " Europe, Austi'alia. Quite doubtfully American, there being no authority other than Wolle's description and figures. 4. B. NORDSTP;DTII Wittrock, 1874, p. 44; Him, 1900, p. 332, PI. LIII, fig. 340 ; P. B.-A., No. 717. Dioecious, nannan- drous, gynandrosporous ; oogonia depressed sub-quadrangular- globose or depressed-globose, patent, below the androsporangia, or very rarely below the terminal setae ; dissepiment of sufful- tory cells superior, rarely sub-median ; epispore of oospore finely pitted or nearly smooth; androsporaugia i -celled, epigyuous ; dwarf males on oogonium ; antheridium interior, stipe slightly curved, shorter than the antheridium. 270 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, 14-17 M diaru., 2-5 diarn. long, oog., 36-43 M " 29-36 M long, andr. cell, 10-12 /j. " 9-12 n " nan., 9-10 M " 23-25 M " Greenland, Conn., Alaska. Europe, Australia. 5. B. POLYANDRIA Cleve in Wittrock, 1870, p. 140; Wolle, 1887, p. 98, PI. LXXXIX, figs. 6-9; Him, 1900, p. 334, PL LIV, fig. 342. Dioecious, nannandrous, idioandrosporous; oogonia subdepressed-globose, patent, under terminal setae or vegetative cells ; dissepiment of suffultory cells superior, more rarely submedian ; epispore of oospore finely pitted or nearly smooth ; androsporangia lo-celled ; dwarf males on oogoniuni ; autheridium interior, stipe slightly curved, shorter than the antheridium. veg. cell, 15-20 M diaru., 3-5 diam. long, oog., 39-46 fj. " 32-42 M long, audr. cell, 12-14 M " n-^SM '•' nan., 8-9 M " 23-26 M " Fla. Europe, So. America. 6. B. DISPAR Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 401 ; Him, 1900, p. 335, PI. LIV, fig. 334. Dioecious, nannandrous, gynandrosporous or idioandrosporous ; oogoniuni large, subdepressed-globose, patent, under terminal setae, or more rarely under vegetative cells ; dissepiment of suffultory cells superior, more rarely sub-median ; membrane of oospore thick, epispore manifestly finely pitted ; androsporangia scat- tered, i-2-?-celled ; dwarf males on oogoniuni ; antheridium in- terior, stipe slightly curved, shorter than the antheridium. veg. cell, 16-21 M diatu., 2-4j< diam. long, oog., 44-56 /j. " 42-51 /ulong. andr. cell, 12-16 /j. " 10-12 M " nan., 9-11 M " 23-36 /x " Greenland. Sweden, 7. B. ANGULOSA Wittrock and Lund in Wittrock, 1874, p. 45 ; Hirn, 1900, p. 336, PI. LIV, fig. 346 ; B. elachistandra Wolle, 1887, p. 97, PL LXXXXVL fig- 5- Dioecious, nan- nandrous, gynandr.osporous ; oogonia patent, biconic- or sub- quadrangular-globose, with truncate apex, sides of cone some- what retuse, below terminal setae, or more rarely below andro- sporangia ; dissepiment of suffultory cells a little above median ; membrane of oospore smooth ; androsporangia scattered or epi- gynous, i-3-celled ; dwarf males on oogoniuni, antheridium interior, stipe slightly curved, shorter than the antheridium. THE GREEN ALGAE OF NORTH AMERICA 271 veg. cell, 13-18 M diam., 1,5-2-2 y, diam. long, oog., 36-42 n " 33-39 M long, andr. cell, 10-11 M " 9-10 n . " nan., 8-9 M " 18-21 M " Europe, Africa. American only by Wolle's reference. 8. B. SETIGERA (Roth) Agardh, 1-817, p. 71; Wolle, 1887, p. 98, PL LXXXVI, fig. i ; Wittr. and Nordst, Alg. Exsicc., No. 702 ; Him, 1900, p. 339, PI. L/V, fig. 351. Dioecious, nan- nandrous, gynandrosporous ; oogonia sub-depressed- or de- pressed-quadrangular-globose, patent, generally below terminal setae, more rarely below androsporangia or vegetative' cells ; membrane of oospore thickened ; dissepiment of suffultory cells usually slightly above median ; epispore of oospore pitted ; androsporangia scattered or more rarely epigynous, i-3-celled ; dwarf males on oogonium or near it ; antheridium interior, stipe slightly curved, shorter than the antheridium. veg. cell, 25-28 /a diam., 2)4-5 diam. long, oog., 70-80 M " 56-65 M long, andr. cell, 16-20 fj. " 10-18 /u. " nan., 11-14 M " 30-36 ^ " Conn., N. J., Fla., S. C. Europe, So. America. B. Canbyi Wood, 1872, p. 202, Pi. XVI, fig. 6, is considered by Hirn to be included in this species. 9. B. CRASSIUSCULA Nordstedt, 1877, p. 30, PL III, figs. 14- 15; Hirn, 1900, p. 341, PL L,V, fig. 352; Wittr. and Nordst., Alg. Exsicc., No. 703. Dioecious, nannandrous, idioandro- sporous ; oogonia depressed-subquadrangular-globose, patent, below terminal setae or more rarely vegetative cells ; dissepi- ment of suffultory cells superior, rarely submedian ; epispore of oospore pitted ; androsporangia 1-4- celled ; dwarf males on oogonium or near it ; antheridium interior, stipe slightly curved, shorter than the antheridium. veg. cell, 22-27 /a. diam., 2)4-5)4 diam. long, oog., 60-78 M " 50-62 ,u long, anth. cell, 16-19 /u. " 10-13 M " nan., 12-14 M " 30-34 fj- " Greenland. Europe, Australia. 10. B. GIGANTEA Pringsheim, 1858, p. 71, PI. VI, fig. i ; Wolle, 1887, p. 99, PL L-XXXVII, fig. i ; Hirn, 1900, p. 347, PL LVII, fig. 359. Dioecious, nannandrous, idioandrosporous ; oogonia sub-depressed-globose or depressed-oboviform-globose, patent, below terminal setae, rarely below vegetative cells; dis- 272 TUFTS COLLEGE STUDIES, VOL. II, No. 3 sepiment of suffultory cells submedian ; epispore of oospore reticulately pitted ; androsporaugia i-5-celled ; dwarf males slightly longer than the oogoniura, on the same ; antheridium interior, stipe about twice as long as the antheridium, bent. veg. cell, 24-32 p diam., 2-3'2 diam. long, oog., 60-70 ,a " 50-58 M long, andr. cell, 18-20 /u " 10-14 yu " nan. stipe, 10-13 M " 2§-45 M " anth. cell, 13-14 M " 20-30 n " Pa. Europe, Australia. ELLIPSOSPORAE. 11. B. MONILE Wittrock and Lund in Wittrock, 1874, p. 50; Him, 1900, p. 348, PI. LVII, fig. 360; P. B.-A., No. 1432; B. nana Wolle, 1887, p. 100, PI. LXXXVII, fig. 6. Monoe- cious, generally few-celled, vegetative cells short, hardly as long as broad, sides often convex, cells then submoniliform or sub- globose ; oogonia ellipsoid, patent or more rarely erect, below terminal setae or vegetative cells ; antheridia i-2-?-celled, erect or patent, subepigynous or scattered. veg. cell, 11-16 /JL diam., r diam. long, oog., 22-25 M " 3°-37 /" long, auth. cell, S-io M " 68 M " Mass., N. J. Sweden. 12. B. NANA Wittrock, i872a, p. 7, PI. I, fig. 9 ; Him, 1900, p. 349, PJ. LVII, fig. 362. Monoecious ; oogonia ellipsoid, patent, below terminal setae or vegetative cells ; antheridia 1-2- celled, erect, more rarely patent, subepigynous or scattered. veg. cell, 10-15 Mdiam., i-i/4 diam. long, oog., 20-25 M " 33-40 M long. anth. cell, 7-9 M " 6-9 M " Greenland, Alaska. Europe. 13. B. MIRABILIS Wittrock, 1870, p. 137, PI. I, figs. 8 and 9 ; Wolle, 1887, p. 100, PI. LXXXVII/figs. 2 and 3 ; Him, 1900, p. 351, PI. LVIII, fig. 365 ; P. B.-A., No. 1431. Monoe- cious ; oogonia ellipsoid or suboblong-ellipsoid, patent, or more rarely erect, below terminal setae or vegetative cells ; anther- idia i-4-celled, erect or patent, subepigynous or scattered. veg. cell, 15-20 M diam., 1/^-2 diam. long, oog., 26-33^ " 46-58 >j. long, anth. cell, 9-12 M " 6-9 M " Greenland, N. J., Minn. Europe, Australia. THE GREEN ALGAE OF NORTH AMERICA 273 14. B. PYGMAEA Pringsheim, 1858, p. 74, PI. VI, fig. 10 ; Wolle, 1887, p. 100, PI. LXXXVII, figs. 4 and 5 ; Wittr. and Nordst., Alg. Exsicc., Nos. 4, 1401; Him, 1900, p. 356, PI. LIX, fig. 372. Dioecious, nannandrotis, gynandrosporous ; vegetative cells short, not longer than wide ; primary filament of the plant curved, short ; oogonia ellipsoid, patent, below ter- minal setae or vegetative cells ; suffultory cell without dissepi- ment; androsporangia subepigynous or scattered, i-?-celled; dwarf males near oogonium, antheridium exterior, i-3-celled. veg. cell, 11-15 M diam., %-i diam. long, oog., 22-25^ " 32-40 M 'long, andr. cell, 7-10 /j. " 6-9 n " nan. stipe, 11-12 M " 15-19 M anth. cell, 7-8 n " 7-8 M " Europe. Only American authority Wolle's reference. 15. B. VARIANS var. SUBSIMPLEX (Wittr.) Him, 1900, p. 357, Pis. LIX, LX, fig. 374; B. subsimplex^NQ\\z, 1887, p. 101, PI. XC, fig. 5. Dioecious, nannandrous, gynandrosporous ; oogonia ellipsoid, erect or more rarely patent, below terminal setae, androsporangia or vegetative cells ; androsporangia scat- tered, epigynous or subepigynous, i-2-?-celled ; dwarf males near or on oogonium ; antheridium exterior, i-3-celled. veg. cell, 13-18 j«diam., i^-i?/ diam. long, oog., 26-30 ,u " 39-46 /j. long, andr. cell, 10-14 M 7-16 M 'nan. stipe, 11-14 M " J5-24 /"• " antb. cell, 7-8 M " 5-7 p. " Pa. Europe, Asia, Australia, So. America. The type with dimensions about one-fifth tr one-fourth larger, and with oogonia more generally patent, is found only in Europe. B. dumosa Wood, 1872, p. 202, PI. XVIII, fig. 6, ac- cording to Hirn should be included in this variet}'. 16. B. RECTANGUI.ARIS Wittrock, 1870, p. 142 ; Wolle, 1887, p. 102, PI. XC, fig. i ; Hirn, 1900, p. 359, PI. LX, fig. 376; P. B.-A., No. 516. Dioecious, nannandrous, gynandro- sporous; little branched, branches often very long ; vegetative cells in cross section subrectangular ; oogonia ellipsoid, patent or more rarely erect, below terminal setae or androsporangia, more rarely vegetative cells ; androsporangia scattered or epigy- nous, i-?-celled ; dwarf males near oogonium or more rarely on it ; antheridium exterior, i-4-celled. 274 TUFTS COLLEGE STUDIES, VOL. II, No. 3 veg. cell, 16-23 fj, diam., iX"2 diain. long, oog., 3I-39V " 45-63 M long, andr. cell, 13-16 M " 10-27 /" " nan. stipe, 14-18 /x " 22-27 /* " anth. cell, S-io /j. " 57 M " Mass., R. I., Conn., Pa. Europe. Var. HILOENSIS Nordstedt, 1878, p. 22; Wolle, 1887, p. 102, PI. XC, figs. 2-3 ; Him, 1900, p. 361, PI. LX, fig. 377. Smaller, vegetative cells longer, androsporaugia generally epigynous, more rarely scattered. veg. cell, 14-19 M diam., 1 34-2j^ diam. long, oog., 28-32 M " 47-51 Mloug. aiidr. cell, 12-14 M " 13-16 M " nan. stipe, 13-14 M " 22-24 M " anth. cell, 8-9 /* " 5-7 M „" Australia . Wolle's reference is the only American report. B. rcdangnlaris and B. varians resemble each other consider- ably, but the latter is more branched and has shorter cells. 17. B. REPANDA Wittrock, 1874, p. 55 ; Wolle, 1887, p. 102, PI. XC, fig. 4 ; Him, 1900, p. 363, PI. LXI, fig. 380 ; P. B.-A., No. 814 ; B. rhadinospora Wolle, 1887, p. 103, PI. LXXXIX, figs. 4 and 5. Dioecious, nannandrous, gynandrosporous ; oogonia subobloug-ellipsoid, patent or erect, below androspo- rangia, terminal setae or vegetative cells ; androsporangia epigynous or subepigynous, i-?-celled; dwarf males near or. on oogonium ; antheridium exterior, i-3-celled ; vegetative cells sometimes repand. veg. cell, 12-17 fj. diam., 2-3>2 diam long, oog., 26-36 M " 43-58 M long, andr. cell, 13-15 A* " ]6-2i M " nan. stipe, 11-15 M " 21-27 ^ " anth. cell, 7-10 fj. " 5-7 M " Greenland, Mass., Me., N. J., Fla. Europe. 18. B. IXSIGNIS Pringsheim, 1858, p. 73, PI. VI, fig. 7 ; Wolle, 1887, p. 101, PL LXXXVIII, figs. 2 and 3 ; Him, 1900, p. 364, PI. L.XII, fig. 383 ; P. B.-A., Nos. 1332, 1430. Dioe- cious, nannandrous, gynandrosporous; oogonia ellipsoid, erect or patent, below androsporangia, terminal setae or vegetative cells ; androsporangia epigynous or subepigynous, more rarely scattered, i-?-cellecl ; dwarf males near or on oogonium : -anther- ididium exterior, i-3-celled. THE GREEN ALGAE OF NORTH AMERICA 275 veg. cell, 19-25 M diam., 2^-3^ diam. long. oog., 46-56 fj. " 70-90 M long. andr. eel], 16-20 M " 9-25 M " nan. stipe, 16-19 M " 29-33 M " anth. cell, 10-13 n " 7-10 p. " Mass., N. J., Alaska. Europe, Australia. Var. RETICULATA (Nordst.) Him, 1900, p. 365, PI. L,XII, fig. 384. Epispore reticulate-denticulate, with doubly dentate longitudinal ridges, the teeth united to each other by transverse ridges ; the longitudinal ridges more or less wavy and crooked, sometimes anastomosing ; dimensions about the same as in the type. The netted surface above described is sometimes found, bu exceptionally and in less degree, on oospores of the type ; the variety merely has it more marked and more generally. Mass. Europe. 19. B. MINOR A. Braun in Kiitzing, 1849, p. 422 ; Wolle, 1887, p. 101, PI. LXXXVII, fig. 7; Him, 1900, p. 369, PI. IvXIII, fig. 390. Dioecious, nannandrous, gynandrosporous ; oogonia subobloug-ellipsoid, erector more rarely patent, below terminal setae, androsporangia, or more rarely vegetative cells ; androsporangia epigynous, subepigynousor scattered, i-?-celled ; dwarf males near or on the oogonium ; antheridium exterior, i-4-celled. veg. cell, 18-25 M diam., 1/^-2 diam. long. oog., 32-42 fj. " 59-69 M long. andr. cell, 15-16 /x " 16-21 M " nan. stipe, 12-15 M " 22-24 <" " anth. cell, 6-10 M " 6-7 p. " N. J. Sweden. Family 6. CHAETOPHORACEAE. Fronds filamentous, except in a few doubtful forms, usually much branched, sometimes united in disk-like expansions ; cells uninucleate, with band- or disk-shaped chromatophore, often somewhat divided or with projections ; with one, rarely more pyrenoids ; hairs almost always present, but varying in charac- ter ; asexual reproduction by 4-ciliate, in some cases biciliate zoo.spores, by aplanospores, akinetes, and with special Palmella and Schizomeris stages in many genera ; sexual reproduction in many genera by gametes similar to the zoospores. This family includes both fresh water and marine forms, but the larger part is fresh water. There is a great range in differ- entiation between the extreme forms, and some forms are in- 276 TUFTS COLLEGE STUDIES, VOL. II, No. 3 eluded here which have little resemblance to the more typical genera, but for which no more appropriate place could be found. KEY TO THE GENERA OF CHAETOPHORACEAE. i. Fronds erect with differentiated base and apex. 2. i. Fronds creeping or expanded, no differentiated base and apex. 5. 2. Fronds less than i mm. high, tips not acute nor setiferous. 22. MlCROTHAMNION. 2. Fronds larger, tips generally acute or setiferous. 3. 3. Filaments united in gelatinous thalli of definite form. 23. CHAETOPHORA. 3. Filaments practically free. 4. 4. Fascicled ramuli different in character from stem. 25. DRAPARXALDIA. 4. Stem, branches and ramuli little differentiated. 24. STIGEOCLONIUM. 5. Filaments originally creeping, producing short, erect branches, closely packed into a thin layer. 6. 5. No dense layer of vertical filaments distinct from basal layer. 8. 6. Fresh water. 7. 6. Marine. 21. PILINIA. 7. Cells of filaments seldom over 10 ,u diam.; sporangia little if any larger than vegetative cells. 20. CHLOROTYLIUM. 7. Cells of filaments seldom under 20 M diam.; fructification in swollen terminal cells. 19. GOXGROSIRA. 8. Filaments more or less united laterally. 9. 8. Filaments not united. 18. 9. Forming an irregular loose incrustation. 9. PSEIDENDOCLONIUM. 9. Forming a definite disk. 10. 10. Disk mouostromatic. u. 10. Disk polystromatic. 14. ii. Setae or hairs more or less abundant. 12. ii. No setae or hairs. 13. 12. Radiating filaments turning up at the end. 10. ENDOCLONIUM. 12. Radiating filaments not turning up at the end. 15. OCHLOCHAETE. 13. Disk formed by filaments radiating from a center. 14. PRINGSHEIMIA. 13. Disk formed by the union of irregular filaments. 13. EPICLADIA. 14. Setae or hairs present. 16'. 14. No setae or hairs. 15. 15. On shells of turtles. n. DERMATOPHYTOX. 15. On algae, stones, etc.; marine. 12. ULVELLA. 16. Hairs gelatinous. 16. CHAETOPELTIS. 16. Setae not gelatinous. 17. THE GREEN ALGAE OF NORTH AMERICA 277 17. Setae articulate. 18. ARTHROCHAETE. 17. Setae inarticulate. 17. CHAETOBOLUS. 18. Cells solitary. i. DIPLOCHAETE. 18. Cells united in filaments. 19. 19. Epiphytic or in loose tissue of other algae. 20. 19. Living in the membrane of other algae or in outer coating of mol- lusks. 24. 20. Fresh water. 4. CHAETOSPHAERIDIUM. 20. Marine. 21. 21. Setae present. 22. 21. Xo setae. 23. 22. Setae arising from the ends of upright cells. 5. ACROCHAETE. 22. Setae arising from small special cells. 8. BOLBOCOLEON. 23. Basal network with short vertical branches. 7. PSEUDODICTYON. 23. Branching irregular, no definite network. 6. ENDOPHYTOX. 24. In cell wall of algae. 2. ENDODERMA. 24. In outer coating of mollusk shells. 3. TELLAMIA. In addition to the genera given in the foregoing key, there are a few others which may be reduced or rudimentary forms belonging to this family ; the cells have the same structure, some species at least produce zoospores and aplanospores, and all have regular vegetative cell-division ; there seems to be no better place for them. i. Cells in older plants borne on stalks formed from the cell wall. 27. UROCOCCUS. i. Cells never stalked. 2. 2. Cells dividing and soon separating, or forming small irregular masses or short filaments. 26. PLEUROCOCCUS. 2. Cell wall persisting and enclosing walls of later generations. 3. 3. Division in one direction. 28. DACTYLOTHECE. 3. Division in two or three directions. 4. 4. Families encircled by one or more opaque bands. 31. GLOEOTAENIUM. 4. No opaque bands. 5. 5. Families spherical or irregular. 6. 5. Families united into subcylindrical, branching thalli. 32. PALMODICTYON. 6. Families enclosed in a spherical, gelatinous envelop. 30. GLOIOCOCCUS. 6. Families with no general envelop. 29. GLOEOCYSTIS. i. DIPLOCHAETE Collins, 1901, p. 242. Cells solitary or a few united into a gelatinous, subfilamen- tous series, globose, flattened, ellipsoid or ovoid, furnished with 2j8 TUFTS COLLEGE STUDIES, VOL. II, No. 3 two or more long, simple, sheathless setae ; chromatophore single, parietal (with pyrenoid?). Reproduction unknown. D. so LIT ARIA Collins, 1901, p. 242. Epiphytic ; cells 25-30 //. diam., with wall 5-8 p. thick, little or not at all lamellose ; setae two, arising from the lower half of the cell, usually opposite, straight, tapering, 4-6 /j. thick at base. Fig. 99. On Laurencia obtusa, Jamaica. W. and G. S. West published, 1903, p. 79, Polychaetophora gen. n. Thallus minute, of few cells, filamentous, or some- times unicellular; cells subglobose, ellipsoid or ovoid, mem- brane very thick and strongly lamellate ; each cell furnished with 8-12 long, flexuous, simple, sheathless setae; chromato- phore single, parietal, often indistinct (with one pyrenoid?). P. lamcllosa sp. unica, PI. CCCCXLVIII, figs. 1-4. Characters of the genus. This seems to be quite distinct from Diplochaete, but G. S. West, 1908, p. 279, PI. XX, figs. 1-6, published Poly- chaetophora simplex sp. n. Cells subglobose or ovoid, membrane thin and homogeneous ; dorsal part of each cell furnished with 2-4 long, flexuous, simple, sheathless setae. If the genus be extended so as to include this species, it would certainly include Diplochaete sol-itaria, and as the genus Diplochactc has priority, that name must be used. It is unfortunate that a more appro- priate name should have to give place to one less appropriate to most of the species, but there seems to be no other course avail- able than to revise the original description of Diplochactc, and to include the two British species of the Wests as D. lamellosa (W. and G. S. West) Collins nov. comb., and D. simplex (G. S. West) Collins nov. comb. 2. ENDODERMA Lagerheim, 1883, p. 74. Frond microscopic, creeping on or within other algae or aquatic plants ; filaments irregularly branched, with or without hairs; cell division mostly terminal; chromatophore a parietal layer with one or more pyrenoids ; zoospores 2-4-ciliate, with .stigma, formed 4 or more in a cell, escaping by a hole and soon germinating ; asexual reproduction by biciliate zoogametes without stigma is probable, but not certain. A genus of a few species, marine and fresh water ; ours all with one pyrenoid and without hairs. THE GREEN ALGAE OF NORTH AMERICA 279 KEY TO THE SPECIES OF ENDODERMA. i. Endophytic, marine, i. Epiphytic, fresh water. 4- 2. In leaves of Zostera. 3. E. perforaiis. 2. In marine algae. 3- 3. Cells averaging 9 /u diarri., cylindrical. i. E. Wittrockii. 3. Cells averaging 6 /x diam., irregular. 2. E.viride. 4. Cells subglobose to ellipsoid. 4. E. Pithophorae. 4. Cells much flattened. 5. E. polymorphum. 1. E. WITTROCKII (Wille) L,agerhehn, 1883, p. 75 ; Hazen, 1902, p. 226, PI. XLII, fig. i ; P. B.-A., Nos. 265, 1469. Fila- ments simple or irregularly branched, with tapering ends ; branches sometimes united laterally ; cells cylindrical, 5-10 /*, usually 9 /A diam., i-i^ diam. long, with one pyrenoid ; growing in the cell walls of brown, less commonly of red algae ; repro- duction little known. Fig. 100. Me. to Conn. Europe. Probably common in summer and autumn, but easily over- looked, as there is seldom anything in the appearance of the host to indicate the presence of the endophyte. It has been found most frequently in Elachista fucicola, but occurs in other algae; at times it is quite common in Desmotrichum undulation. 2. E. VIRIDE (Reinke) lyagerheim, 1883, p. 74 ; Entodadia viiidis Reinke, 1879, p. 476, PI. VI. Filaments usually much branched, 3-8 /u, usually 6 /JL diam., cells 1-6 diam. long, some- times cylindrical, oftener irregularly swollen and contorted, with one pyrenoid ; terminal cell blunt or tapering ; growing in cell walls of various algae. Mass. Europe. A smaller plant than the preceding, and with more irregular branching. In Europe it has a more southern range than E. Wittrockii, and it is to be expected in localities south of Cape Cod. 3. E. PERFORANS Huber, 1892, p. 3 16, Pi. XIV. Filaments 3-5 /LI diam., endophytic in the dead leaves of Zostera marina ; cells more or less irregular in form and of varying length, with one pyrenoid ; larger, rounded cells formed here and there, up to 14 /A diam; asexual reproduction by ovoid or subspherical 4-ciliate zoospores with stigma, formed in the larger cells, 8 in a cell. Me., Mass. Europe. The slender filaments creep among the epidermis cells of the host, while the larger cells and sporangia are formed within the large cells of the inner layer of the Zostera. The zoospore comes to rest on the surface of a Zostera leaf and emits a tube 280 TUFTS COLLEGE STUDIES, VOL. II, No. 3 which penetrates the outer layer of the host, and begins to branch almost immediately. The species is probably to be found everywhere in the dead and faded Zostera leaves in marsh pools. 4. E. PITHOPHORAE West, 1905, p. 283. Epiphytic; fila- ments not over 200 //.long, irregularly branched, branches atten- uate, more or less concrete ; cells 25-38 /x diam., subglobose, ellipsoid, ovoid, or oblong ; apical cell 10-16 ^ diam. ; cell with one pyrenoid, membrane 3-4 ^ thick. Barbados. This species was found growing on Pithophora Cleveana, on or in the immediate vicinity of the intercalary spores ; like the following species it is not at all endophytic, and thus connects Endoderma with Epicladia, but the filaments do not unite to form a definite disk. 5. E. POLYMORPHUM West, 1905, p. 283, PI. CCCCLXIV, fig. 19. Epiphytic; filaments up to 250 /u. long, irregularly branching and anastomosing; cells flattened, polymorphous, very irregular in form, 15-39X6-20^; thickness of membrane 3-7.5 fj. ; cell with one pyrenoid. Barbados. This species occurs on the same host as E. Pithophorae , but on vegetative cells only ; the flattened cells, with very irregular outline, seem to distinguish it from its companion. 3. TELLAMIA Batters, 1895, p. 315. Frond of radiating, irregularly branched filaments, creeping in the periostracum of mollusca ; parietal chromatophore nearly filling the cell, with one pyrenoid ; cells often swollen ; asexual reproduction by zoospores, formed in slightly swollen cells. The two known species occur often in company, in the outer skin of the shells of Littorina, forming a more or less dense net- work, but not penetrating the shell itself. The color of the shells they inhabit is changed from bright yellow to some shade of dull yellow or brown. T. CONTORTA Batters, 1895, p. 316, PI. XI, figs. 18-24. Filaments yellowish green or brown, densely and irregularly branched; cells 6-9X3-10 /A, ovoid or ellipsoid; branching of two kinds, horizontal, similar to the main filament, branches sometimes falcate or coiled, often anastomosing ; vertical, branches short, often united laterally, with acute terminal cells ; inflated cells, up to 20 fj. diam., occasionally occurring in the horizontal branches. Figs, in, 112. On Littorina palliata Gould. Southern Mass. England. THE GREEN ALGAE OF NORTH AMERICA 281 The irregularly and densely branched fronds form an open or almost continuous layer in the membrane, sending short branches up and down, to the outer surface of the membrane, or to the surface of the shell. In England it is generally ac- companied by the other species, T. intricata Batters, with more cylindrical cells and looser branching ; this species has not yet been noticed in this country. 4. CHAETOSPHAERIDIUM Klebahn, 1891, p. 7. Frond microscopic, epiphytic on various algae ; cells globose or hemispherical, with disk-shaped chromatophore and one py- renoid, bearing above a very long, delicate sheathed hair ; cells dividing by a horizontal wall, the daughter cell then passing to the side of the mother cell, or emitting a tubular projection, at the end of which is formed a new setiferous cell ; reproduction by motile spores, but character and development unknown. When a setiferous cell has divided and formed a tube, the con- tents of the lower (daughter) cell passes through the tube to the new cell ; the tube either disappears as in C. globosum, or re- mains an empty utricle as in C, Pringsheimii. KEY TO THE SPECIES OF CHAETOSPHAERIDIUM. i. Utricles short and evanescent ; general gelatinous envelop present. i. C. g lob o sum. i. Utricles well developed ; no general gelatinous envelop. 2. C. Pringsheimii. 1. C. GLOBOSUM (Nordst.) Klebahn, 1893, P- 3°6« PI- XIV, figs. 5-10; Hazen, 1902, p. 229; Aphanochaete globosa Wolle, 1887, p. 1 19, 'PI. CV, fig. 5. Cells 12-18 /x diam., sheath 16-17 /"• long, 2-3 fji diam. ; cells closely set, utricles inconspicuous, gen- eral gelatinous coating ample. On algae, chiefly Oedogonium. N. H. to N. J., Neb. Europe. 2. C. PRINGSHEIMII Klebahn, 1891, p. 7 ; 1892, p. 268, PI. IV. Cells 9-12 /a cliam., sheaths 13-18 p. long, about 2 p. diam. ; cells united by well developed, persistent utricles into creeping filaments, sometimes with erect ends ; no general gelatinous coating. On algae, chiefly Coleochacte. Fig. 104. Canada, near Lake Superior. Europe. There may be some doubt whether the plant figured by Hazen, 1902, PI. XL,II, figs. 3 and 4, is really C. Pringsheimii, as stated, or a form of C. globosiim ; a comparison of this plate with Klebahn's plate would seem to indicate that they were not the same species. 282 TUFTS COLLEGE STUDIES, VOL. II, No. 3 5. ACROCHAETE Pringsheim, 1862, p. i. Epiphytic or endophytic ; filaments creeping, branching, artic- ulate, bearing short erect branches, which often end in a slender tube containing a long, slender seta ; chromatophore parietal, with one. or more pyrenoids ; sporangia formed from terminal cells of erect branches, bearing no setae, producing many bicili- ate zoospores, which germinate to produce the parent form ; sexual reproduction reported, but uncertain. Marine. KEY TO THE SPECIES OF ACROCHAETE. i. Cells seldom 2 diam. long. 2. A. parasitica. i. Cells longer, 2-6 diam. i. A. repens. 1. A. REPENS Pringsheim, 1862, p. 2, PL II; P. B.-A., No. 1279. Creeping filaments 7-9 ^ diam., cells 2-6 diam. long, usually with several pyrenoids; sporangia elongate-ovoid, 8-12 <2o-4O fj.. Fig. 101. In the cortical layer of Chorda Jilitni, Laininaria, etc. Mass. E-urope. The setae are sometimes very abundant in this species, some- times so rare that a careful examination is needed to find any. 2. A.- PARASITICA Oltmanns, 1894, p. 208, PI. VII, figs, i- 10 ; Rosenvinge, 1898, p. 114. Creeping filaments 8-12 /A diam., cells about i *~ diam. long, with disk-shaped chromatophore and one pyrenoid ; sporangia somewhat clavate, usually projecting above the surface of the host plant, about 25 X 10-12 p.. In old fronds of FUCKS. Greenland. Europe. 6. ENDOPHYTON Gardner, 1909, p. 371. Filaments endophytic in red algae, sparingly and irregularly branched in the medulla of the host, more freely near the sur- face ; cells \vith band-shaped chromatophore and one pyrenoid ; sporangia at the surface of the host, on short erect branches, producing pyriform, biciliate zoospores. E. RAMOSUM Gardner, 1909, p. 372, PI. XIV, figs. 3 and 4. Filaments 4-6 p. diam., often tortuous and irregular, cells 6-8 diam. long ; sporangia clavate, 10-12 /* diam., pointed when young ; zoospores numerous, 3 p. diam., escaping by an opening at the end of the sporangium. Fig. 121. In fronds of Iridaea laminarioides Bory, Gigartina radula (Esper) J. Ag. Cal. Forming patches usually a few mm. diam., but which may be confluent and cover considerable areas, usually near the base of the frond of the host. In Gigartina the patches show more reddish than the rest of the frond. 7. PSEUDODICTYON Gardner, 1909, p. 374. Filaments endophytic in larger algae, much branched, long THE GREEN ALGAE OF NORTH AMERICA 283 and tortuous, the branches at right angles, forming a network among the cells of the host ; short branches arising from the cells of the network, the terminal cell of each branch develop- ing into a sporangium at the surface of the host. Cells with parietal chromatophore and one large pyrenoid. Evidently nearly related to Endophyton, but there is a sharper differentiation between the two parts of the frond, the definite horizontal network, and the short fruiting branches. The net- work has a superficial resemblance to Microdidyon, but the re- semblance is probably only superficial. P. GENICULATUM Gardner, 1909, p. 374, PI. XIV, figs. 5 and 6. Young cells 3-4 p. diam., becoming larger with age ; vertical branches of 2-3 cells arising from practically all the cells of the network ; sporangia 8-12 ^ diam. Fig. 120. In the cortical layer of Laminaria Sinclaiiii, near San Francisco, Cal. The patent branches of the main filaments usually reach to a neighboring filament, thus forming a network with subrec- tangular meshes, each enclosing 4-8 cells of the host ; from this network arise vertically short branches reaching to the surface of the host and terminating in sporangia with rounded ends ; the nature of the reproductive bodies formed in these sporangia is not known. The plant is found chiefly in the terminal part of the blade of the host. 8. BOLBOCOLEON Pringsheim, 1862, p. i. Frond microscopic, epi- or endophytic in various algae ; fila- ments creeping, branching, consisting of irregular rounded cells, on the upper (outer) side of which are borne smaller bulb- shaped cells, prolonged into a tube, from which projects a long, slender hair ; ^chromatophore in the filament cells a parietal per- forate layer with 5-10 pyrenoids ; in the piliferous cells an irregularly toothed plate with two pyrenoids. Reproduction by biciliate zoospores, produced in large numbers in the filament cells ; whether sexual or asexual is not known. Only one species. B. PILIFERUM Pringsheim, 1862, p. 8, PI. I ; Farlow, 1881, p. 57 ; Hazen, 1902, p. 227 ; P. B.-A., No. 1225. Vegetative cells 1 2- 1 6 /u, diam., 2-3 diam. long. Fig. 108. Newfoundland to R. I.; California. Europe. Not uncommon in summer and autumn in various loose- tissued marine algae, seldom in such quantity as to be noticeable without microscopic examination, but occasionally occurring in 284 TUFTS COLLEGE STUDIES, VOL. II, No. 3 such quantity as to give a whitish appearance to algae normally brown. The circumstances favorable to its development favor also other small epiphytes, and it is usually accompanied by Calothrix parasitica, Streblonema species, etc. It is usually found in brown algae, Lcathesia diffonuis, Castagnca viresccns, Mesogloia divaricata, Ralfsia Borncti, etc. ; sometimes in old plants of Dictyosiphon and Scytosiphon, where the normally com- pact cortical layer has become loose ; occasionall)T in red algae such as Nemalion tmdtifidum and N. Andersonii. 9. PSEUDENDOCLONIUM Wille, IQOI, p. 29. Frond of much and irregularly branched filaments, packed to- gether in an irregular layer, with short, erect branches, and with very short rhizoids ; cells of irregularly rounded shape ; chromatophore a small parietal disk with one pyrenoid. Asexual reproduction by akinetes, and by 4-ciliate zoospores without stigma. Only one species. P. SUBMARINUM Wille, 1901, p. 29, PI. Ill, figs. 101-134; P. B.-A., No. 1124. Cells 6-7 p. diam., forming a pseudopar- enchymatous layer on the surface of and penetrating more or less into the substance of woodwork, near high water mark ; akinetes of two types, one with wall little thickened, germinat- ing at once ; the other with thick walls and remaining in the resting state for some time ; zoosporangia slightly larger than the vegetative cells, producing each 4-8 4-ciliate zoospores, about 4 fj. diam., escaping by a short neck; germinating im- mediately. Fig. 87. Me., Mass., R. I. Europe. This species forms a fine green granular coating on shaded woodwork near high water mark, and in appearance much re- sembles the common Pleurococcus vulgaris ; -but is distinctly fila- mentous, and appears to be a reduced form belonging to the Chaetophoraceae. 10. ENDOCLONIUM Szymanski, 1878, p. 18. Frond endo- or epiphytic, forming larger or smaller disks, filaments erect at the margin, and here and there in the disk, forming erect, branching tufts. Asexual reproductiou by akin- etes, and by small biciliate and larger 4-ciliate zoospores, with red stigma, formed one to several in a cell ; sexual reproduction by small biciliate gametes. A genus of minute plants inhabiting the leaves of various aquatic plants, probably closely allied to Stigeodonium. We THE GREEN ALGAE OF NORTH AMERICA 285 have only one species, and that somewhat doubtful, details of development and reproduction being insufficiently known. E. ? MOEBIUSIANUM De Toni, 1889, p. 208 ; Stigeoclonium sp., Mobius, 1888, p. 239, PL IX, fig. 3. Disk up to 500 u diam., composed of filaments radiating from a common center ; cells 5 ju. diam., 1-2 diam. long; rising above into a short, papilla-like extension ; occasionally seta-bearing. Fig. 88. Porto Rico. The erect filaments are much less developed than in most species of the genus ; Mobius' first supposition may be correct, that it is a species or state of growth of Stigeoclonium, ii. DERMATOPHYTON Peter, 1886, p. 191. Forming rounded or irregular disks, on the shells of turtles, of closely packed cells in several layers, below sending cunei- form projections into the shell ; asexual reproduction by (bicili- ate ? ) zoospores formed by repeated division of the contents of the enlarged cells of the outer layer. Only one species. D. RADIANS Peter, 1886, p. 191 ; D. radicans Potter, 1887, p. 251, PL VIII. Disks up to 12 mm. diam., composed of squarish cells, originally in branching radial series, but soon united to a parenchymatous layer, several cells thick, except at the margin; the superficial cells enlarging to form sporangia, from which the contents are discharged in the form of zoospores, the cells below then becoming sporangia, the thickness of the frond being maintained by successive divisions of the cells by horizontal planes. Fig. 93. Mass. Europe. The name is wrongly quoted by Potter as D. radicans, and the error has been copied by De Toni, 1889, Wille, 1900, and others ; no one seems to have taken the trouble to look up the original description. 12. ULVELLA Crouan, 1859, p. 288. Fronds forming small disks on larger plants or other objects, firmly attached by the under surface, originally monostromatic, of radiating, laterally united, dichotomous filaments ; later polystromatic, except at the margin ; cells writh parietal chro- matophore and one pyrenoid, arranged in more or less definite vertical series ; biciliate zoospores formed in the central cells, 4-8-16 in a cell, escaping by an opening at the top. Marine. KEY TO THE SPECIES OF ULVELLA. i. On stones and shells. 3. U. lens, i. On algae. 2. 286 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. Strictly epiphytic. 4. U. prostrata. 2. Penetrating the host more or less. 3. 3. Gelatinous, up to 75 M thick, not confluent. 2. U.fucicola. 3. Not gelatinous, up to 250 /u thick, confluent. i. U. conflucns. 1. U. CONFLUENS Rosenvinge, 1893, p. 924, fig. 39. Form- ing green, confluent incrustations on old stipes of Laminaria longicruris ; when mature, to 250 /JL thick, smooth, composed of more or less regular, closely united, vertical filaments, diverging towards the margin; cells 10-12 yu diam., 2-4 diam. long, the disk- or cap-shaped chromatophore at the top ; dissepi- ments horizontal or oblique, somewhat curved upward ; terminal cells of the same size and form as the others, but with rounded top and richer contents : sporangia formed from the superficial cells, little changed in form or size, but with tip more acute ; zoospores 30-40 in a cell, escaping by a terminal opening. Greenland. Northern Europe. At first this plant is mouostromatic, resembling a Prinxshcimiti, and even in this state produces spores. It continues to increase in thickness, and empty sporangial cells may be found quite a distance below the surface ; from the lower surface short fila- ments penetrate the host plant to a greater or less depth. 2. U. FUCICOLA Rosenvinge, 1893, p. 926, fig. 40 ; Olt- manns, 1894, p. 211, PL VII, figs. 11-13. Frond pulvinate or hemispherical, to 75 /j. thick, somewhat gelatinous, composed of oblong cells arranged in more or less distinctly radiating series ; cells 5-7 fj. diam., 3-5 diam. long, wall not sharply marked off from the general gelatinous coating; chromatophore parietal, occupying the middle part of the cell ; all cells, except perhaps the basal layer, developing into sporangia, which swell to twice the size of the vegetative cells, and are pushed out from among them ; zoospores 6-10 in a sporangium. On old plants of FKCKS. Greenland. Northern Europe. Quite different both in habit and structure from U. conHucns, forming smaller, not confluent, more gelatinous fronds, with smaller cells, and less sharply differentiated sporangial layer. It penetrates the host plant, but not to such an extent as U. con flue ns. 3. V . LENS Crouan, 1859, p. 288, PI. XXII, fig. E. Fronds orbicular, 1-3 mm. diam., cells 15-20 p. diam. in center of frond, near the margin 10-15X20-30^; frond usually not over three layers thick in the center of the frond. Fig. 102. North Carolina, on stones and shells. Europe. THE GREEN ALGAE OF NORTH AMERICA 287 Though this is the original species of the genus, the details of development and reproduction are not as well known as in the two later described species. 4. U. PROSTRATA Gardner, 1909, p. 373, PI. XIV, figs, i and 2. Frond epiphytic, the disk of 2-3 layers of cells in the middle, of one layer near the margin, composed of radiating filaments, free at the margin, all firmly adherent to the host ; cells each with a band-shaped chromatophore and one p)rrenoid, 6-7 /x diam., about i diam. long near the center of the disk, in- creasing to 2)2 diam. at the tips of the filaments ; terminal cell blunt ; color very dark green. On Iridaca laminarioides Bory, near San Francisco, Cal. Forming obscure, circular cushions, 2-3 mm. diam. on the host, usually in the sterile part of the frond. The absence of hairs and tapering cells would seem to justify placing this species in Ulvella, but until something is known of the repro- duction, there must be some uncertainty. 13. EPICLADIA Reinke, 1888, p. 241. Frond microscopic, composed of filaments irregularl}7 and densely branching, forming a coating ou the surface of Bryozoa ; branching in one plane, when well developed taking the form of a central membrane with filamentous margin ; chromatophore a parietal layer with one pyrenoid. Reproduction by zoospores (gametes ?) formed manj^ in a cell, and escaping by a round hole in the wall. Only one species. E. FI«USTRAE Reinke, 1889, p. 86; iSSga, p. 31, PI. XXIV, figs- 5-9; Hazen, 1902, p. 225, PI. XLJI, fig. 2 ; P. B.-A., No. 1 60. Cells of the central plate irregularly polygonal, usually 7-12 p diam., occasionally larger; of the free filaments short- cylindrical or irregular, 5-10 /j. diam. Fig. 94. Greenland to N. Y. Europe. On the northern New England coast this plant is common in spring and summer; at New York, Hazen reports it in May, but did not find it in summer and autumn. The Fuci that cover the rocks in the literal zone are often overgrown with Flustra, Sertularia, etc. ; these are usually of a whitish or yel- lowish color, but when covered by the Epidadia, they are dark green ; the alga is thus easily detected. 14. PRINGSHEIMIA Reinke, 1888, p. 241. Frond a monostromatic disk on the surface of other algae ; marginal cells flat, interior cells wedge-shaped, with their a88 TUFTS COLLEGE STUDIES, VOL. II, No. 3 length vertical to the basal plane ; growth radial by division of the marginal cells ; chromatophore a large disk with one pyre- noid. Asexual reproduction by biciliate zoospores with red- brown stigma, formed in the central cells, few in each cell, escaping through an opening in the wall. Sexual reproduction in distinct plants from the asexual, by biciliate gametes with reddish stigma, many in a cell. Only one species. P. SCUTATA Reinke, iSSga, p. 33, PI. XXV; P. B.-A., No. 1524. Disk 1-2 mm. diam. ; cells varying much in size and shape; zoospores 15 ^ diam., gametes 4 /i. On Zostera and various marine algae. Fig. 95,. Greenland to Conn., Jamaica. Europe, 15. OCHLOCHAETE Thwaites in Harvey, 1846-1851, PI. CCXXVI. Filaments creeping, articulate, branching ; all or nearly all the cells bearing each a very long, inarticulate seta, base not swollen. O. FEROX Huber, 1892, p. 291, PI. X; Rosenvinge, 1893, P- 931, fig. 42 ; P. B.-A., No. 1521. Filaments radiating from a center, more or less closely united to form a round or somewhat irregular disk ; branching lateral, occasionally a branch rising above the rest and forming locally a tissue two cells thick ; cells rounded or angular, up to 30 /x, diam., chromatophore parietal with one pyrenoid ; setae tubular, continuous with the cells ; central cells enlarging to form sporangia, up to 30 //, diam., which develop each 20-30 4-ciliate zoospores, developing at once on coming to rest. Fig. 92. On Cladophora, Chacto- ii/orpha and Zostera. Greenland, Mass. Europe. O. hystrix Thwaites has been reported from Washington, Setchell and Gardner, 1903, p. 219, but there is some doubt as to the determination. 1 6. CHAETOPELTIS Berthold/iSyS, p. 215. Frond a more or less rounded disk, attached by the lower sur- face, gelatinous, composed of rounded cells, in more or less dis- tinct radial series ; cells uninucleate, with one pyrenoid, some- times with long, gelatinous, hair-like prolongations from the cell wall ; sexual reproduction by the union of biciliate gametes ; asexual reproduction by 4-ciliate zoospores with red stigma. Fresh water. There is some question as to the character of the chromato- phore in this genus ; Berthold, 1878, in the original diagnosis, stating that many small disk-shaped chromatophores were THE GREEN ALGAE OF NORTH AMERICA 289 found in a cell; Huber, 1892, however, considers that the ap- parent separate • disks are thickenings in a single parietal coating. C. americana (Snow) uov. comb. ; Ulvella americana Snow, 1899, p. 309, PI. VII. Disk 1-3 mm. diam. ; marginal cells 10-17X5-13 M< squarish or horizontally elongate; central cells 10-13 /* diam., vertically elongate, ultimately in several layers; superficial cells sometimes producing evanescent gelatinous hairs; zoospores 4-ciliate, 10-15X8-13 /x, oval or nearly spheri- cal, with numerous oil globules and large brick-red stigma ; 4-8-16 produced in a cell, from which they escape together, surrounded by a common gelatinous envelope ; germinating immediately after coming to rest, and producing a plant like the parent. Fig. 96. Mich. The 4-ciliate zoospores with prominent red stigma, issuing from the mother cell in a common envelope, and the gelatinous hairs, all indicate Chactopeltis rather than Ulvella as the proper genus for this plant. Moreover, Ulvella is a strictly marine genus as far as known, and has a structure more parenchym- atous and less gelatinous. From C. orbicitlaris Berthold and C. minor Mobius it would seem to be distinguished by the polystromatic disk. Some peculiar conditions noted by Miss Snow, such as germinating zoospores forming two or four zoospores of a secondary genera- tion ; also the assuming of a sort of Palmella-state, may be due to conditions of cultivation, but at any rate raise interesting questions. 17. CHAETOBOLUS Rosenvinge, 1893, p. 928. Frond epiphytic, hemispherical or more rarely subglobose ; cell division in all directions ; in the hemispherical frond the cells of the basal margin radiately arranged ; superficial cells, except those of the basal margin, and those covered by other algae, produced into long inarticulate setae, continuous with the cells producing them ; reproduction by zoospores produced in the superficial cells? Marine. Nearly allied to Ochlochaete, but normally polystromatic, while Oclilochaete is normally monostromatic. Only one species. C. GIBBUS Rosenvinge, 1893, p. 928, fig. 41. Frond 100-150 /j. diam., cells of irregular rounded form, up to 30 ^ diam., with dense chromatophore ; the free superficial cells with very long, slender setae, 4-5 /u. diam. at the base, much more slender near 290 TUFTS COLLEGE STUDIES, VOL. II, No. 3 the tip ; the very narrow passage through the seta not parti- tioned off from the cell ; zoospores have not been observed, but the appearance of the fronds sometimes indicates that they are probably formed in the superficial, bristle-bearing cells. On Chaetomorpha mclagoniitui. Fig. 98. Greenland. This plant usually grows in company with Lithodcrma and other epiphytic algae, which often so cover it that the develop- ment of the setae is much obstructed. 18. ARTHROCHAETE Rosenvinge, 1898, p. no. Frond epiphytic or endophytic, incrusting, orbicular, pseudo- parenchymatous, sending towards the interior of the host plant filaments which branch and spread in the medullary layer of the latter ; superficial vegetative cells usually bearing each a long seta, separated from the cell by a partition, and itself with one or two partitions ; sporangia formed from superficial cells, con- stituting a continuous layer, obovoid or cylindrical ; the zo- ospores escaping by an opening at the top. Marine. Only one species. A. PENETRANS Rosenvinge, 1898, p. in, fig. 24. Frond to \y PI- XVII; Phyc. Univ., No. 290. At first in minute tufts, up to 4 mm. diam., soon confluent to a continuous layer; filaments parallel, densely packed, 6-12 yu. diam., of two kinds, one kind bright green, cells i^j-2 diam. long, the other lighter, nearly hyaline, cells 2-6 diam. long ; akinetes orange or vermilion, formed only from the shorter cells, 9-15 /* diam., globose or oblong-ellipsoid. Fig. 86. N. Y., Ky. Europe. 21. PILINIA Kiitzing, 1843, p. 273. Basal layer of abundantly branched filaments, from which arise erect filaments, simple or branched, sometimes terminating in articulate hairs ; chromatophore covering the cell wall ; sporangia roundish, ovoid or clavate, terminal or lateral on erect filaments or sessile on the basal layer, the contents form- ing numerous biciliate zoospores, which escape through an opening at the summit ; development unknown. KEY TO THE SPECIES OF PILINIA. i. Filaments often ending in hairs. 7. P. uiaritiiua. i. Hairs not present. 2. 2. Endopbytic. 3. P. endophytica. 2. Not endophytic. 3. 3. Erect filaments short, densely packed. 4. 3. Erect filaments longer, yellowish. 5. 4. Dark green ; filaments 8-12 n diam.; on live shells. i. P. Ilunatiae. 4. Yellowish green ; filaments 2-5 n diam.; on pebbles. 2. P. minor'. 5. Forming a rather firm, spongy coating on woodwork. 5. P. i-iinosa. 5. Forming a thin, soft coating. 6. 292 TUFTS COLLEGE STUDIES, VOL. II, No. 3 6. On shells, pebbles, etc.; sporangia on erect filaments. 4. P. Reinschii. 6. On woodwork ; sporangia on basal layer, rarely lateral on erect filaments. 6. P. Morsei. 1. P. LUNATIAE Collins, 1908, p. 123, PL L-XXVII, figs. 1-3; Acroblaste Reinschii P. B.-A., No. 162. Basal filaments soon becoming united into a subparenchymatous layer, cells of varying shape and size, roundish or angular, up to 15 ^ diam.t erect filaments 8-12 /j. diam., increasing in size upward, usually 5-6 cells in length, quite rarely up to 10 cells, densely branched and very compact, cells varying in size and shape in the same filament ; terminal cell becoming the sporangium, differing but little from any other cell of the filament ; color deep green. On live shells of Lunatia hcros Adams. Mass. Very common on Lunatia shells at Revere Beach, Mass., but not reported elsewhere. It forms a very deep rich green coating at the flat spiral of the shell, but on living shells only. The substance is very compact, the filamentous character being made out with difficulty. The spores are produced in the terminal cells of the upright filaments, slightly enlarged, but not other- wise changed. It is a plant of spring and early summer chiefly. 2. P. MINOR Hansgirg in Foslie, 1890, p. 146, PL II, figs. 17-22. Stratum thin-coriaceous or almost crustaceous, yellow-green, more or less extended ; basal layer dense, indi- vidual filaments indistinguishable ; erect filaments irregular, vertical or inclined, as small as 2 /u. diam. at the base, increas- ing in size upward to as much as 7 /A at the summit ; not much branched. Sporangia terminal, pyriform but rather irregular, 2O-24X 10-12 p.. On pebbles by the seashore. Mass. Northern Europe. The distinction between the basal and the erect filaments is less than in P. Lunatiae, but the sporangia are more clearly dif- ferentiated. In the only recorded American locality, it grew on pebbles between high and low tide marks, and when the tide was out was wet with cold water from a spring. 3. P.- ENDOPHYTICA Collins, igoSc, p. 156. Frond of no definite form, consisting of usually short, simple or branched filaments, creeping among the filaments of the host ; cells vari- able in form and size, cylindrical, clavate, subspherical or irregular, 7-22 ^ diam., 1-5 diam. long; chromatophore light green, sometimes filling the cell, more commonly cup-shaped, at the upper end of the cell. Sporangia terminal, spherical or THE GREEN ALGAE OF NORTH AMERICA 293 ovoid, up to to 30 p. diaiii., containing numerous spores. In fronds of Ralfsia Borneti Kuckuck. Me. to Conn. 4. P. REINSCHII (Wille) Collins, 1908, p. 125 ; Acroblaste sp. Reinsch, 1879, p. 365, PI. III. A. Basal layer of monosi- phonous filaments, with rounded cells about as long as broad ; vertical filaments about ^2 mm. high, 5-8 /u diam., cells about twice as long as broad, cylindrical or slightly constricted at the nodes ; sporangia ovoid, 16-20X20-25 ^ ; terminal or apparently lateral on the erect filaments. On shells and pebbles. Mass. In this species the basal layer shows the filamentous character throughout, even when the filaments are laterally united ; often they remain practically free. The color is a yellowish, some- what olivaceous green ; it has some resemblance to a small species of Ectocarpus. It is often mixed with Micro chaete grisea Thuret, Calothrix species, and other small algae. 5. P. RIMOSA Kiitzing, 1843, p. 273 ; 1854, p. 20, PI. XC. ; P. B.-A., No. 971. Forming a dense, yellowish green stratum; basal layer of somewhat irregular cells, more or less torulose ; erect filaments reaching a height of 2 mm., simple or branched, cylindrical or torulose, cells 7-10 /u diam., length of cell, 1-2 diam. ; reproduction unknown. On woodwork near high water mark. Me. Europe. Forms a very compact coating, that can be removed in pieces of considerable size ; Calothrix pnhnnata grew with it at the Maine locality, nearer low water mark ; the stratum was con- tinuous, Calothrix below, Pilinia above, the two mixed for a space in the middle. 6. P. MORSEI Collins, 1908, p. 126, PI. LXXVII, figs. 4-6. Basal filaments irregularly contorted, more or less united ; cells rounded, 8-15/0. diam., often divided longitudinally and forming a subparenchymatous membrane of two or more layers ; erect filaments up to 2 mm. high, 7-11 /u diam:, cells 1-2 diam. long, cylindrical or slightly moniliform ; sporangia ovoid or pyriform, on the basal la)rer, sessile or on a few-celled pedicel. Fig. 90. On woodwork, N. J. Showing more differentiation than the preceding species, assimilative and fertile growths being both distinct from the basal layer. 7. P. MARITIMA (Kjellm.) Rosenvinge, 1893, p. 933, fig. 43 ; Chaetophora maritinia Kjellman, 1877, p. 51, PI. IV, figs. 15 and 16. Frond subspherical, 1-3 mm. diam., basal layer not 294 TUFTS COLLEGE STUDIES, VOL. II, No. 3 strongly developed ; erect filaments 6-10 p. diani. ; cells about as long as broad, terminating in an inarticulate hair, or in an ovate-ellipsoid cell ; sporangia terminal, clavate, 11-12X16-21 /u,. Greenland. This species forms a continuous layer, in company with Calo- thrix ; the subspherical gelatinous thalli distinguish it from the other species of the genus. Under this should be included, ac- cording to Rosenvinge, C. pellicula Kjellman, 1883, p. 286, PL XXXI, figs. 4-7, which forms a thin slimy membrane on wood ; Rosenvinge was unable to find the intercalary sporangia to which Kjellman refers, and which, if confirmed, would require the removal of the plant to another genus. 22. MICROTHAMNION Nageli in Kiitzing, 1849, p. 352. Frond very minute, consisting of a branching, monosiphonous filament, attached by a bulbous base ; stem and branches of about the same size ; first partition in branch some distance above base ; terminal cell blunt ; cells cylindrical, with thin wall ; chromatophore a thin sheet, more or less completely covering the cell wall, without pyrenoid. Asexual reproduc- tion by ovoid, biciliate zoospores without stigma, germinating immediately. A genus of very minute plants, the frond not reaching the height of i mm. ; in appearance resembling a small Trente- pohlia, but differing in that the spores are produced in any cell of the filament, practically unchanged ; not in more or less specialized sporangia. KEY TO THE SPECIES OF MICROTHAMNION. i. Ramification dense; main stem and branches indistinguishable. i. M. Kutzingianum. i. Ramification open ; main stem distinguishable throughout. 2. J\f. strictissimum. i. M. KUETZINGIANUM Nageli in Kiitzing, 1849, p. 352; Hazen, 1902, p. 191, PL XXVI, fig. i ; PL XXVII, figs. 2-4; P. B.-A., No. 568. Up to 200 fj. tall, very densely and irregu- larly branched, main stem and branches indistinguishable ; ramuli one- to several-celled, patent or curved ; cells cylindrical or slightly clavate, 3-4 ^ diam. in all parts of the frond, usually 2-4 diam. long, occasionally considerably longer ; chromato- phore bright green, usually covering the entire cell wall. Fig. 83. Mass, to N. Y. Europe, New Zealand. Forming a thin coating on sticks, woodwork, etc., in streams ; also in greenhouses. THE GREEN ALGAE OP NORTH AMERICA 295 2. M. STRICTISSIMUM Rabenhorst, Algen, No. 829 ; Hazen, 1902, p. 191, PI. XXVI, figs. 2-5 ; P. B.-A., No. 1425. Up to 600 /j. tall, erect, branching mostly alternate, the main stems dis- tinguishable throughout ; branches erect or ascending ; cells cylindrical, 2.5-4 /^ diam., about the same size all through the frond, 3-12 diam. long, or even more ; chromatophore thin, pale green, often only partially covering the wall. Conn., N. Y. Europe, So. America. In similar stations to the preceding species ; distinguished by the greater size, longer articulations, and different ramification. Var. MACROCYSTIS Schmidle, 1899, p. 169, PL VII, figs. 1-3 ; Hazen, 1902, p. 192, PI. XXVII, fig. i. Taller, branching more open ; branches more slender than main stem, somewhat tapering ; chromatophore pale and narrow ; tips of branches colorless. Mass., N. Y. Europe. Found growing on dead leaves in a rain water ditch. 23. CHAETOPHORA Schrank, 1813, p. 124. Filaments arising from a palmelloid base, and united by a firm gelatinous substance into thalli of definite form ; filaments re- peatedly branched, of about the same diameter throughout, ramuli often in fascicles, frequently terminating in long setae. Chromatophore a parietal band with one or more pyrenoids. Asexual reproduction by biciliate zoospores, formed in the cells of the ramuli ; akinetes from any cell. The filaments are much like those of Stigeoclonitiin , but the branching has more of a dichotomous appearance ; the whole is imbedded in a gelatinous mass of definite form, spherical, tuber- cular, or elongate and branching. The plants are attached to sticks, stones, etc., and are common in clear running water in spring ; less common in quiet water. KEY TO THE SPECIES OF CHAETOPHORA. i. Thalli elongate, lobed and branching. 4. C. incrassata. i. Thalli globose or tuberculose. 2. 2. Branching loose and spreading. i. C. elegans. 2. Branching erect. 3. 3. Branches fascicled at the summit. 2. C. pisifonnis. 3. Branches not fascicled at the summit. 3. C. attenuata. i. C. ELEGANS (Roth) Agardh, 1812, p. 42; Wolle, 1887, p. 116, PL CUT, fig. 4-10 ; Hazen, 1902, p. 211, PL XXXVII ; P. B.-A., No. 1026. Thalli globose or oftener tuberculose, up to i cm. diam, light green, rather soft ; filaments radiating from the center, di-trichotoaiously branched and fasciculate above ; 296 TUFTS COLLEGE STUDIES, VOL. II, No. 3 branches loose and spreading, except sometimes at the tips ; ramuli short-pointed or setiferous ; cells in main filaments 6-u, usually 8 p. diarn., 3-10 diam. long ; in ramuli 5-7 /u. diam., 1-4 diam. long. Fig. 85. Mass, to N. J., Jamaica, Washington. Europe. Ranging in size from hardly visible spheres to tuberculose and confluent forms, over i cm. diam. ; mostly in spring, but occa- sionally at any time except when the brooks are frozen. In general character much like the two following species, but generally of lighter color, softer texture, and less regularly spherical shape. 2. C. PISIFORMIS (Roth) Agardh, 1812, p. 43 ; Harvey, 1858, p. 70; Wolle, 1887, p. 116, PI. CIII, figs. 1-3, 12-15; Hazen, 1902, p. 212, PI. XXXVIII, fig. i. Thalli globose or tubercu- lose, 2-5 mm. diam., rather dark green, firm, seldom confluent ; filaments radiating from the center, dichotomously, rarely tri- chotomously branched, branches erect or appressed, ramuli slender, acute, sometimes setiferous ; cells in main filaments usually 6-7 /A diam., sometimes slightly more or less, 3-6 diam. long; in ramuli 4-6 ^ diam., 1-3 diam. long. Me. to N. J., Washington. Europe. The habit characters by which this differs from C. elegans are given under the latter species ; microscopically, C. pisiformis has more slender filaments and more erect branching. The charac- ter of presence or absence of setae, formerly supposed to be of specific importance, is now known to be of no value, varying with age and circumstances. This species is especially a plant of running water. 3. C. ATTENUATA Hazen, 1902, p. 213, PI. XXXIX ; P. B.-A., No. 1520. Thalli globose or nearly so, not confluent, 2-5 mm. diam., bright green, dense and firm ; filaments di- trichotomously branched, very erect and nearly parallel, not fasciculate ; ramuli acute or setiferous ; cells of main filaments 5-5.5 ju diam., 5-10 diam. long ; of the ramuli about 4 /x, rather longer in proportion ; branch-bearing cells often broadened and forked at the top ; descending rhizoids abundant in the lower part of the frond. Mass., Conn., N. J. In habit quite like C. pisiformis, but distinguished by more slender filaments, very regular branching, ramuli long and rather distant, rhizoids abundant. A plant of quiet water, and of summer rather than of spring. 4. C. INCRASSATA (Huds.) Hazen, 1902, p. 214, PI. THE GREEN ALGAE OF NORTH AMERICA 297 XXXVIII, figs. 2 and 3 ; P. B.A., 1330 ; C. endivaefolia Harvey, 1858, p. 69; Wolle, 1887, p. 117, PI. CIV ; C. cornu-damac P. B.-A., No. 68. Thalli irregularly extended, lobed, laciniate, or branched, main filaments elongate, closely packed in skeins or strands, with alternate or secund branches bearing densely fascicled, usually setiferous ramuli ; cells of main filaments 8-16 ju, diam., 2-6 diam. long, cylindrical or inflated; ramuli often curved, often torulose, 6-n /u, diam., cells 1-2 diarn. long. Generally distributed. Europe, So. America. Thoroughly distinct from the three preceding globular species, but varying so much in form and ramification that it has received many specific and varietal names, but no clear lines can be drawn. Much of the variation appears to be due to the rapidity of the water in which it grows ; between the forms with somewhat flattened and lobed thallus, 2-3 cm. long, and the slender, much branched, filamentous forms, several dm. long, every gradation can be found. 24. STIGEOCLONIUM Kiitzing, 1843, p. 253. Frond mucilaginous, composed of a branching filament, with- out much distinction in character between main filaments and branches ; terminal cells pointed or prolonged into a seta ; chromatophore a parietal band, filling the smaller cells, zonate in the larger. Asexual reproduction by 4-ciliate zoospores with a red stigma ; also by akinetes which produce 2-ciliate zo- ospores, by aplanospores, and also by a Palmella stage. Sexual reproduction by conjugation of 2-ciliate gametes with a red stigma. A rather large genus of fresh water algae, very well limited but whose species show few sharp dividing lines. KEY TO THE SPECIES OF STIGEOCLONIUM. i. Opposite branching predominant. 2. i. Alternate branching predominant. 8. 2. Filaments 10 /u diarn. or less. 6. .5". tenue. 2. Filaments 11-30 /u diam. 3. 3. Lower cells much inflated. 5. S. ventricosum. 3. Lower cells slightly or not at all inflated. 4. 4. Lower cells not over 2 diam. long. 5. 4. Lower cells 2-8 diam. long. 6. 5: Lower cells seldom as long as broad ; ramuli tapering, thorn-like. 4. S. subuligerum. 5. Lower cells usually longer than broad ; ramuli short-pointed. i. S. lubricum. 298 TUFTS COLLEGE STUDIES, VOL. II, No. 3 6. Lower cells 2-5 diam. long. i. S. lubricum var. varians. 6. Lower cells 3-8 diam. long. 7. 7. Ratuuli pointed. 2. S. amoenuw. 7. Ramuli setiferous. 3. S. flagelliferum. 8. Filaments short, tufted. 9. 8. Filaments more elongate. 12. 9. Of thermal waters. 7. S. thermale. 9. Of ordinary temperatures. 10. 10. Tips obtuse or short-pointed. 8. 5. nanum. 10. Tips attenuate or setiferous. n. n. Ramuli scattered. 13. ii. Ramuli densely fasciculate. 10. S. glomeratum. 12. Filaments 5-7 M diam. n. S. attenuatum. 12. Filaments S-n n diam. 12. S. stagnatile. 12. Filaments 12-18 M diam. 13. 6". subsecundum. 13. Filaments 7-9 ,u diam. 9. S. aestivale. 13. Filaments 4-6 M diam. 14. 6". minus. i. S. LUBRICUM (Dillw.) Kiitzing, 1845, p. 198; P. B.-A., No. 866 ; 5". tenue var. lubricum Wolle, 1887, p. in ; Myxoncma lubricum Hazen, 1902, p. 195, PI. XXVIII, figs, i and 2. Tufts up to 30 cm. long, dark green, filaments much branched, the branching principally of the opposite type, but often several pairs, single branches or whorls arising from adjacent cells, these cells being subglobose and smaller than other cells in the same filament ; ramuli abundant, opposite, scattered, or near the ends of the branches in more or less dense fascicles ; smaller than the branches from which they arise, but only slightly if at all tapering ; usually ending in a short point, but sometimes setiferous; lower cells somewhat swollen, 14-17 /* diam., 2/3-2 diam. long, rarely more, with broad zonate chromatophore ; ramuli 6-7 p. diam., cells about as long as broad. Fig. 84. Ontario, Mass, to N. J., Alaska. Europe. The largest, and at least in the eastern states, the most com- mon of our species ; all the species with prevailingly opposite branching are grouped round this, resembling it in most charac- ters, but with special developments on one or more lines. Like most'of the species of Stigeoclonium it is a spring plant, inhabit- ing clear running water. Var. varians (Hazen) nov. comb. ; Myxonema lubricum var. varians Hazen, 1902, p. 198, PI. XXVIII, figs. 3 and 4 ; PI. XXXIII, figs. 4 and 5 ; P. B.-A., No. 1075. Tufts short, not exceeding 2 cm. ; filaments seldom over 12 ^ diam., cells 2-5 diam. long, with thin wall ; ramuli longer-pointed. Mass, to New Jersey. THE GREEN ALGAE OF NORTH AMERICA 299 Appearing like a small and delicate state of S. lubricum, but considered by Hazen, who collected it in many localities, as a well defined variety. 2. S. AMOENUM Kiitzing, 1845, p. 198; Wolle, 1887, p. 113, PI. XCVIII, fig. 4; P. B.-A., No. 1073; Myxonema amoenum Hazen, 1902, p. 199, PI. XXIX. Light green, tufted, up to 10 cm. long ; filaments much branched, after the type of ^. lubri- cum ; the ramuli tapering and pointed but rarely setiferous ; cells in main branches cylindrical or slightly inflated, 11-16 //. diam., 3-8 diam. long, occasionally as much as 15 diam. ; shorter above, in the upper branches about as long as broad ; ramuli 6-8 /u. diam. at base. Mass., R. I., Conn. Europe. 3. S. FLAGELLIFERUM Kiitzing, 1845, p. 198; 1853, PL X, fig. i ; Wolle, 1887, p. 112, PI. XCVII, fig. i ; P. B.-A., No. 408 ; Myxonema flagelliferum Hazen, 1902, p. 199. Tufts up to 2 cm. long, bright green ; branches mostly in pairs, 2-4 pairs on successive globose cells ; ramuli flagelliform, tapering into long setae ; lower cells 14-18 ^ diam., 4-8 diam. long, C37lindrical or slightly inflated ; ramuli 9-10 /u diam. at base. Mass., Conn. Europe. This and the preceding species have much in common, but ,5". flagelliferum is larger, with more elongate and tapering branches, and more abundant and better developed setae. 4. S. SUBULIGERUM Kiitzing, 1849, p. 354; Myxonema stibu- ligerum Hazen, 1902, p. 200, PI. XXX. Tufted, less than i cm. long ; much branched after the type of S. lubriaim, but branches spreading, ramuli divaricate, tapering from the rather thick base to an acute point, or occasionally into a short seta ; cells cylindrical, about as long as broad, quite covered by the dense chrornatophore ; main branches 12-16 ^ diam.; ramuli 6-9 /j. diam. at base. N. Y., N. J., Cal. Europe. Distinguished by the nearly uniformly opposite, divaricate branching, thorn-like ramuli, and dense chrornatophores. 5. S. ventricosum (Hazen) nov. comb.; Myxonema vcnfri- cosuuj Hazen, 1902, p. 201, PI. XXXI. Tufted, up to i cm. long ; main branches as in .S*. lubricum ; ramuli alternate or opposite, short, tapering to the rounded tip or into a short, rather obtuse seta; lower cells much inflated, 14-16 /u. diam. at the ends, 27-30 /u. at the middle, length 45-110 /t; ramuli 6-8 ft diam. at the base ; chrornatophore a narrow zone in the large, inflated cells, occupying the greater part of the smaller cells. N. J. The strongly inflated cells, with comparatively narrow zonate 300 TUFTS COLLEGE STUDIES, VOL. II, No. 3 chromatophores, remind one of a Draparnaldia, and seem to characterize the species sufficiently. 6. S. TENUE (Ag.) Kutzing, 1843, p. 253; Wolle, 1887, p. no, PI. XCVI, fig. ii ; Wittr. and Nordst., Alg. Exsicc., No. 1429; Myxonema tcnue Hazen, 1902, p. 202, PI. XXXII. Tufts up to i cm. high, bright green ; filaments slender, 7-10 /u, diam. below, 5-6 /u, in the ramuli ; cells cylindrical or slightly swollen, 1-3 diam. long ; in ramuli about as long as broad ; main branches solitary or opposite, not many pairs together ; ramuli numerous, scattered or opposite, short, erect, tapering to an acute point or a very slender seta. Mass., Conn., Vermont, N. Y., Cal. Europe. A slender, loosely branched species, forming a transition from the opposite-branching 5*. lubriauu group, to the less luxuriant, alternately branched species. 7. S. THERMALE A. Braun in Kutzing, 1849, p. 353; 1853, PI. II, fig. 4 ; Wolle, 1887, p. in, PI. XCVI, fig. i ; Myxonema thcrmalc Hazen, 1902, p. 203. Filaments with somewhat creep- ing base, freely branching, ramuli distant, alternate or opposite, erect or patent, tapering to a point ; cells 7.5-12 ^ diam. below, 1-2 diam. long ; in ramuli 3-5 diam. long. A plant of warm springs and hot water escapes from mills, etc. 8. S. NANUM (Dillw.) Kiitzing, 1849, p. 354; Wolle, 1887, p. 112, PI. XCVI, fig. 10 ; P. B.-A., No. 867; Myxonema nanum Hazen, 1902, p. 204. Two to three mm. high ; branch- ing alternate, ramuli tapering, obtuse or short-pointed ; cells 6-8 /x diam., 1-2 diam. long. Neb., So. Dakota, Cal. Europe. A not very strongly characterized species ; perhaps a state of some other, but at present there is no evidence to connect it with any other form. As P. B.-A., No. 1375, there was dis- tributed, as forma subsimplex Collins, a form from California, with filaments even shorter than in the type and hardly at all branched. 9. S. aestivale (Hazen) nov. comb.; Myxonema acstivale Hazen, 1902, p. 205, PI. XXXIII, figs. 1-3; P. B.-A., No. 1074. Light green, forming dense tufts up to i cm. high ; base palmelloid ; branching alternate or dichotomous, erect ; main filaments 7-9 //. diam., rarely more; cells 2-6 diam. long below, about as long as broad above, thin-walled, somewhat swollen ; ramuli few, scattered or somewhat approximate near the sum- mit, frequently attenuate into fine setae. Growing in dense tufts along the edges of troughs and fountains. Vermont, Mass., N. Y., Conn. THE GREEN ALGAE OF NORTH AMERICA 301 10. S. glomeratum (Hazeu) nov. comb.; Myxonema glomer- atum Hazen, 1902, p. 205, PI. XXXIV. Tufts up to i cm. long, with palmelloid base ; branches few below, alternate ; above more frequent, usually alternate, rarely opposite, more or less densely fascicled near the summit, the ramuli tapering to an acute tip or a long seta ; cells of main filaments cylindrical or slightly swollen, 11-14 /*diam., 2-7 diam. long, with broad, zonate chromatophore ; cells of ramuli 6-8 ^ diam., 1-2 diam. long, with dense chromatophore. In pools and fountains. Conn., N. Y. 11. S. attenuatum (Hazen) nov. comb.; Myxonema atten- uation Hazen, 1902, p. 206, PL XXXV; P. B.-A., No. 1328. Tufted or forming dark green lubricous skeins, up to nearly half a meter long ; dichotomously divided near the base into many filaments, sparingly branched above ; ramuli short, spi- nescent or flagelliform, solitary or 2 or 3 arising from the same point, less often opposite, tapering to an acute tip or a very slender seta; cells cylindrical, 5-7 fj. diam., 2-5 diam. long; chromatophore thin and somewhat broken. Vermont, Mass., Conn. Growing in watering troughs, where it has the habit of an Ulothrix rather than of a Stigeoclonium. In the two localities where it has been studied, it was found from Feb. to Nov. 12. S. stagnatile (Hazen) nov. comb.; Myxonema stagnatile Hazen, 1902, p. 207, PL XXXVI, figs, i and 2. P. B.-A., No. 1329. Forming floccose, floating masses; filaments elongate, bearing at long intervals solitary or opposite ramuli ; short, thorn-like, often curved, tapering to a sharp point or a long seta; cells 8-n /u. diam., 1-3 diam. long, occasionally longer ; ramuli 7-9 M diam. at base. Mass., N. Y. Always found floating, in company with filamentous algae of various kinds. It is of course probable that it is attached at some early stage, but this has not been observed. 13. S. SUBSECUNDUM Kiitzing, 1843, p. 253 ; Wolle, 1887, p. 112, PL XCIX, fig. 2?; Myxonema subsecundum Hazen, 1902, p. 207, PL XXXVI, fig. 3. Forming loose, pale green or yellowish tufts; filaments elongate, sparingly branched, 12- 18, usually 16 ^ diam.; cells 3-10 diam. long ; branches never opposite ; some branches elongate like the main stem, others shorter ; cells 2-3 diam. long ; all branches attenuate towards the apex; cells cylindrical, or dissepiments very slightly con- stricted. In ditches. N. J., So. Carolina, Jamaica. Europe. A soft, pale green plant, especially characterized by the 302 TUFTS COLLEGE STUDIES, VOL. II, No. 3 scanty ramification and the strongly tapering branches resem- bling >S. stagnatile, but with larger cells, branches never opposite, forming dense tufts ; never found in a floating state. 14. S. minus (Hausg.) nov. comb.; S. longipilus var. minus Hausgirg, 1886, p. 227; P. B.-A., No. 865. Forming dense tufts up to 5 mm. high ; filaments radiating from a palmelloid base, 4-6 p. diatn., cells 2-4 diam. long ; filaments sparingly and irregularly branched, ending in a long hair ; procumbent fila- ments arising near the base of the erect filaments, similar or slightly larger. Mass. This plant was found growing on stems of plants in a clay-pit, Medford, Mass., June, 1900. It seems to be the S. longipilus var. minus of Hansgirg, but as pointed out by Hazen, S. longi- -bilns is a plant of much larger dimensions. The small form seems to continue of the same size, not to pass into the typical 5". longipilus. 25. DRAPARNALDIA Bory, 1808, p. 399. Filaments united by a soft, gelatinous coating, not forming a thallus of definite form ; main filaments attached by basal rhi- zoids, more or less branched, stout, bearing dense lateral fas- cicles of ramuli, much smaller than the main filaments, often setiferous. Chromatophore in the stem and large branches a parietal baud, sometimes perforated, with numerous pyrenoids ; in the cells of the ramuli, a layer covering the wall, with few pyrenoids. Asexual reproduction only from the cells of the ramuli, by 4-ciliate zoospores with red stigma, germinating im- mediately ; also by akinetes and aplanospores ; sexual repro- duction by conjugation of 4-ciliate gametes, which, however, may germinate without copulation. Common plants of running water, chiefly in spring ; distin- guished from Stigeoclonium and Chaetophora by the sharp con- trast between the main stems and the ramuli ; also from Chacto- t>hora by the thin, amorphous character of the gelatinous coating. KEY TO THE SPECIES OF DRAPARNAUHA. i. Rachis of the fascicle of raniuli distinct throughout. 2. i. Rachis of the fascicle of ramuli indistinct. 3. 2. Fascicles erect, lanceolate, elongate. i. D.plumosa. 2. Fascicles spreading, broadly ovate, acuminate. 2. D. acitta. 3. Cells of main branches inflated, chromatophore narrow. 3. D. glomerata. 3. Cells of main branches cylindrical, chromatophore broad. 4. D. platyzonata.' THE GREEN ALGAE OF NORTH AMERICA 303 i. D. PLUMOSA (Vauch.) Agardh, 1812, p. 42; Harvey, 1858, p. 72; Wolle, 1887, p. 109, PL XCIV; Hazen, 1902, p. 218, PL XL, figs, i and 2; P. B.-A., Nos. 21, 1224. Tufts up to 15 cm. long, branches spreading or ascending, solitary or opposite, fascicles of ramuli single, opposite, or whorled, usually erect, dense, lanceolate or ovate-acuminate in outline, with pro- longed percurrent rachis ; ramuli erect or ascending, subulate or setiferous ; cells of main filaments and branches subcylindri- cal, 45-70 /Ji diam., 1-3 diam. long; ramuli 6-10 ^ diam., 1-4 diam.Jong; chromatophore occupying ^-^i the length of the large cells, proportionately broader in the smaller cells. Ver- mont to California. Europe. A widely distributed and fairly common species ; its most distinctive character is found in the dense, plumose fascicles of ramuli, acuminate in outline, with percurrent rachis. 2. D. ACUTA (Ag.) Kiitzing, 1845, p. 230; 1853, PL XIII, fig. 2; Hazen, 1902, p. 219; P. B.-A., No. 1072. Tufts up to 10 cm. long, branches spreading or ascending, solitary or oppo- site, fascicles of ramuli single, opposite, or whorled, somewhat dense, ascending or spreading, broadly ovate to lance-ovate and acuminate in outline, rachis usually distinct ; ramuli ascending, often curved, subulate or setiferous ; cells of larger branches somewhat inflated, or nearly cylindrical above, 50-90, rarely no p. diam., 1-2 diam. long; chromatophore not over half the the cell length in width ; ramuli 6-10 (j. diam. Mass, to N. J., Oregon. Europe. Quite close to D.pliunosa, and perhaps only a variety, but usually with larger stems, branching more spreading, fascicles of ramuli broader in outline. 3. D. GLOMERATA (Vauch.) Agardh, 1812, p. 41 ; Harvey, 1858, p. 72 ; Wolle, 1887, p. 108, PL XCII ; Hazen, 1902, p. 220, PL XL, figs. 3 and 4; P. B.-A., No. 20. Tufts usually dense, up to 8 cm. long ; filaments much branched, branches spreading or horizontal, solitary or opposite, moniliform, bear- ing very numerous scattered, opposite, or whorled fascicles of ramuli ; fascicles mostly set at right angles to the stem and sessile, broadly orbicular to elliptical, rachis indistinct, ramuli spreading, crowded, subulate, often long-setiferous ; cells of main branches much swollen, 50-90 or even 125 /JL diam., *4-2 diam. long; chromatophore here not over half as broad as the length of the cell, but proportionally broader in the smaller branches ; ramuli 6-9 i*. diam. Fig. 89. Maine to N. J., Minn., Cal. Europe. 304 TUFTS COLLEGE STUDIES, VOL. II, No. 3 A very common spring plant in brooks, etc., varying consid- erably in appearance, but easily recognized. At first it is deep green, but becomes quite pale later in the season, the empty cells remaining after the escape of the zoospores. 4. D. PLATYZONATA Hazen, 1902, p. 222, PI. XL,!. Loosely tufted, up to 7 cm. long ; branches mostly opposite or whorled, horizontal; fascicles of ramuli at right angles to the stem, dis- tinctly stalked, broadly orbicular in outline, ramuli somewhat symmetrically radiating from the summit of the rachis ,or its branches, subfusiform, acuminate or setiferous ; cells of the larger branches cylindrical or slightly constricted at the nodes, 50-90 p. diam., i diam. long or less; chromatophore very wide, nearly or quite filling the cell, often reticular ; ramuli 6-n /u. diam. Vermont, Mass., N. J. Though reported from few localities only, this seems to be a quite distinct species, and it will probably be found in other places. 26. PLEUROCOCCUS Meneghini, 1842, p. 30. Cells round, or angular by mutual pressure, dividing in all three directions, remaining attached in irregular masses of up to 32 cells or even more ; chromatophore in form of small grains or united to a disk, with or without a pyrenoid ; zoospores, aplanospores and zoogametes have been reported. P. VULGARIS Meneghini, 1842, p. 38, PI. V, fig. i ; Nageli, 1848, p. 65, PI. IV. E, fig. 2; P. B.-A., No. 760. Cells 4-6 /x diam., singly spherical but becoming angular when in contact, often 2 to many cells continuing attached. On wood, stone, and brick, in moist or shaded places. Fig. 106. From Greenland south. Europe. Probably the nearest to omnipresent of all the algae, as it is found in practically every station, not submerged, where moist- ure is occasionally to be had. It forms the thin green coating found on stone walls, buildings and trees, especially on the north side ; this preference for the north side of trees is usually so marked that one can determine the cardinal points of the compass, except in dense woods. It is found as far north as Greenland ; whether it has a southern limit, going towards the equator, is not certain. It forms a somewhat friable coating in dry weather, becoming gelatinous in rain ; the cells may separate promptly after divid- THE GREEN ALGAE OF NORTH AMERICA 305 ing, but oftener continue attached in larger or smaller numbers, the families of no definite form, sometimes seeming like the be- ginning of filaments ; spores of various species of algae may be found germinating in company with Pleurococcus, and it is not always easy to distinguish them. Miss Julia W. Snow has pro- posed, 18993, p. 189, a genus Pseudo- Pleurococcus, with two species, P. botryoides and P. vulgaris, but as pointed out by Chodat, 1902, the characters on which the new genus is founded belong also to Pleurococcus vulgaris. There is little or no agreement among writers on algae as to what should be included in this genus other than P. vulgaris ; taken in a broad sense it will include in whole or in part Proto- coccus, Cystococcus, Chlorococciun , Chlorosphaera and Pseudopleuro- coccus. So little is known as to American forms that might be placed in these genera, that only a mention need be given of such forms, with a reference that will indicate where to look for fuller particulars. P. KiltzingiiQ. S. West, 1905, p. 287, PI. CCCCLXIV, figs. 9 and 10, from Barbados, is said by the author to be at once distinguishable from P. vulgaris by the small size of the cells, and by the yellow-green color. The diameter given, however, 3.8-5.7 /A, differs little from what we have noted for P. vulgaris, and the shade of green in the latter varies under varying condi- tions of moisture and light. P. regularis Artari, reported in plankton of Lake Erie, Snow, 1903, p. 381, PL II, fig. IX, is a problematical form, referred by Chodat to Coclastruin, by Oltmanns to Ghlorclla Beyerinck, itself a doubtful genus, claiming to include beside the present species, the species included in this work under Palmellococcus and Zooclilorclla . P. aquaticus Snow, 1903, p. 383, PI. Ill, fig. X, appearing in laboratory cultures, must remain uncertain, as long as nothing is known of it in a natural condition. Chlorosphaera lacustris Snow, 1903, p. 386, PL IV, fig. XIV, and C. parvula Snow, I.e., p. 386, PL IV, fig. XV, must also be considered questionable. Protococcus ovalis Hansgirg in Foslie, 1890, p. 159, PL III, fig. 12. Another doubtful form; occurring in clefts of rocks 306 TUFTS COLLEGE STUDIES, VOL. II, No. 3 near high water mark in Norway, and in a similar station on the coast of Maine. The cells are ovoid or ellipsoid, 8-ioX9-12 /A, with thin wall and yellow-green contents, solitary or in a formless, not very mucilaginous layer. 27. UROCOCCUS Kiitzing, 1849, p. 206. Cells spherical, solitary, originally green, changing to some shade of red or yellow, with large, granular, bell-shaped chro- matophore and no pyrenoid ; wall thick, lamellate, the older layers ultimately breaking at one side, but remaining attached at the other, forming a stipe-like prolongation, of about the same breadth as the cell. A somewhat doubtful genus, which may ultimately be ab- sorbed in Glococvstis ; it is represented in America by three forms, which have been described as species, but their distinct- ness is certainly open to question. KEY TO THE SPECIES OF UROCOCCUS. i. Marine. 3- U. Foslieanns. i. Fresh water. 2. Cells 6-15 M diam. i. U. Hookerianns. 2. Cells 25-50 M diam. 2. U. insignis. 1. U. HOOKERIANUS (Hass.) Kiitzing, 1849, p. 206; Wolle, 1887, p. 201, PL CXXIII, fig. 13; Haeinatococcus Hookenanus Hassall, 1845, p. 325, PL LXXX, fig. 4. Cells globose or ellipsoid, 6-13 ^ diam., blood-red when mature ; stipe densely annulate, often forked. Pa. Europe. 2. U. INSIGNIS (Hass.) Kiitzing, 1849, p. 207; Wolle, 1887, p. 201, PI. CXXIII, figs, ii and 12; Phyk. Univ., No. 82; Haematococcus insignis Hassall, 1845, p. 324, PI. L,XXX, fig. 6. Cells globose, 23-53 P- diam., or including thick, lamellate wall, up to 70 /u. diam., brownish, orange-yellow or brick-red when mature. Mass., Pa., Alaska, Vancouver. Europe. In early stages like a Glococystis, with cells 3-5 ^ diam. ; in- creasing in size and number of cells, but continuing in gelati- nous colonies until the cells are about io/xdiam., when they become free and develop the annular wall and later the stipe. The species has been studied by Richter, 1886, and it would seem that the formation of the stipe does not occur until the period of active vegetation is past ; for the greater part of its existence the species develops as a Glococystis. 3. U. FOSLIEANUS Hansgirg in Foslie, 1890, p. 156, PI. Ill, figs. 4-6. Marine; cells 8-18 fj. diam., green, becoming THE GREEN ALGAE OF NORTH AMERICA 307' dull orange ; diam., including wall, 15-25 p. ; stipe rather short, distinctly annulate. Growing among various algae, mostly blue- green, in crusts near high water mark. Fig. 105. Me. Europe. Much like U. insignis, and perhaps rather to be considered a small marine form of that species ; in its early stages not unlike Gloeocystis zostericola . Var. FERRUGINEUS L,agerheim, 1882, p. 75, PI. Ill, figs. 31- 33. Rusty yellow ; larger than the type, up to 90 /j. with wall. Greenland. Northern Europe. 28. DACTYLOTHECE L,agerheim, 1883, p. 64. Cells cylindrical or oblong-ellipsoid, straight or slightly curved, with rounded ends, solitary or 2-4 united into a family, with broad, lamellate, persistent membrane ; chromatophore parietal, occupying 73 of the cell wall, without pyrenoid ; asexual reproduction by division in one direction only. Fresh water. Like Gloeocystis, except for cell division being in one direction only, with consequent difference in the shape of the cells and families ; reproduction by zoospores and akinetes has not been observed. D. CONFLUENS (Kiitz.) Hausgirg,* 1888, p. 140; Gloeothece confiuens Nageli, 1848, p. 58, PI. I.G, fig. i ; Wolle, 1887, p. 325, PI. CCX, fig. 6; Phyk. Univ., No. 483^ Cells 1.5-2.5 /«, diam., 1/4-3 diam. long, with ample membrane, in few-celled families, 10-15 /A diam. Forming a gelatinous, yellowish or flesh-colored layer on rocks. Fig. 118. Mass. Europe. 29. GLOEOCYSTIS Nageli, 1848, p. 65. Cells spherical, with bell-shaped chromatophore, covering most of the cell wall, and one pyrenoid ; wall thick, more or less lamellate ; asexual reproduction by repeated cell division, sev- eral generations of cells often remaining enclosed in the original mother cell wall, and the walls of the intermediate generations ; also by biciliate zoospores, and by akinetes. A genus very closely resembling in appearance, cell division, etc., the blue-green Glococapsa ; differing in structure and color of contents and by the formation of zoospores ; the latter have, *The attribution of this name to Hansgirg may be open to question, as he does not actually use the binomial. His words are "Zu dieser Gat- tung diirfte Gloeothece confluens (Ktz.) Nag., (Gloeocapsa conjincns Ktz. ) in Rabh. Alg. Exsicc., No. 1231, und wahrscheinHch auch noch Gloeothece dis/ans Stiz. gehbren." There seems here to be involved, in addition to the usual rules of nomenclature, the question as to the exact signification of a German auxiliary verb. 308 TUFTS COLLEGE STUDIES, VOL. II, No. 3 however, been observed in only a few species ; other species have been passed back and forth between the two genera ; the chief difficulty is not in knowing whether an alga under exam- ination belongs to the Chlorophyceae or to the Cyanophj'ceae, but in knowing whether the long lost original of a scanty specific description belonged to one or the other. Fresh water and marine. It is quite probable that supposed species of this genus are merely stages of other algae, like the " Palmella-stage " ; others seem to be permanent, and not connected with any other organ- ism. The only sure test would be prolonged cultures under varying conditions ; but observations for a series of years of G. vesicnlosa and G. rupestris, in a state of nature, have shown great uniformity. Other species are here included which seem fairly well marked. KEY TO THE; SPECIES OF GLOEOCYSTIS. i. Marine. 6. i. Fresh water. 2. 2. Cells not over 6 M diarn. 3. 2. Cells 6-12 /j. diam. 4. 3. Forming a soft coating, or scattered among other algae. 5. 3. Forming a firm, cartilaginous layer. 4. G. Paroliniana. 4. Cells 6-8 n diam., bright green. i. G. vesicnlosa. 4. Cells 9-12 /ti diarn., more or less brownish. 3. G. gi°as. 5. On pottery and glass in greenhouses. 6. G.fenestralis. 5. On wet rocks. 2. G. rupestris. 6. Cells averaging over 15 /u. diam. 5. G. zostericola. 6. Cells averaging 4-6 M diam. 7. G. scopuloniin. 1. G. VESCICULOSA Nageli, 1848, p. 66, PI. IV. F. ; Wolle, 1887, p. 196, PI. CLXVI, figs. 9-15 ; P. B.-A., No. 609. Cells bright green, globose or flattened, solitary or 2-8 forming a family 16-35 /"• diam.; membrane soft, hyaline, lamellate; among other algae, on wet rocks, etc., rarely forming a distinct stratum. Me., Mass. Europe. 2. G. RUPESTRIS (Lyngb.) Rabenhorst, 1863, p. 128 ; Wolle, 1887, p. 196, PI. CLXVI, figs. 19-21 ; P. B.-A., No. 608. Cells green, globose, 3-5 //. diam., solitary or 4-12 forming a family 12-60 /u. diam. ; membrane soft, hyaline, lamellate, quite wide. Greenland, Mass. Europe. In the same stations as G. vcsiculosa, and often in company with the latter ; distinguished by the smaller cells, more in a family, with relatively wider membrane. THE GRKEN ALGAE OF NORTH AMERICA 309 3. G. GIGAS (Kiitz.) Lagerheitn, 1883, p. 63; Phyk. Univ. No. 638 ; G. amp/a Wolle, 1887, p. 196, PI. CLVI, figs. 2-8. Cells globose or oblong-ellipsoid, 9-12 p. diatn., solitary or 2-8 forming a family 45-95 /"• diam. ; membrane thick, distinctly lamellate ; contents green, but containing brownish oil globules ; forming gelatinous, roundish, dull green or brownish masses on submerged objects. Me., Mass., W. I. Europe. When the brownish oil drops are abundant, it is called var. nifescens, but the distinction is not worth a name. 4. G. PAROLINIANA (Menegh.) Nageli, 1848, p. 65; Phyk. Univ., Nos. 23, 597 ; Microcystis Paroliniana Meneghini, 1842, p. 78, PI. X, fig. 2. Cells 3-6 p- diam., globose, 2-8 forming a family not over 24 p. diam.; membrane hyaline, lamellate ; con- tents yellowish ; forming a firm incrusting stratum on wet rocks, etc., about 2 mm. thick. Mass., N. H., Canada. Europe. Distinguished by the yellowish color, and the small families united into a firm stratum. 5. G. zostericola (Farlow) nov. comb.; Gloeocapsa zosteri- cola Farlow, 1882, p. 68; Gheocystis chrysophthalina P.B.-A., No. 219. Marine; cells spherical or by mutual pressure flattened-hemispherical, 19-26X9-11 p-, 2-4 united to form a family 40-100 p. diam.; membrane ample, lamellate; contents brownish; forming brownish masses on Zosfeni marina. Wood's Hole, Mass.; has not been observed elsewhere. 6. G. FENESTRAI.IS (Ku'tz.) A. Braun in Wittr. and Nordst., Alg. Exsicc., No. 444; P. B.-A., No. 566; Gloeocapsa fencs- tralis Kiitzing, 18493, PI. XV, fig. 5. Cells globose or oblong, 2-4.5 /"• diam., with membrane 7-15 n, solitarj^ or 2-18 forming a family, 15-50 /u, diam.; membrane hyaline, thick, lamellate, chromatophore bright green ; forming a thin, soft, pale or }-el- lowish stratum in greenhouses, etc. Mass., R. I. Europe. 7. G. SCOPULORUM Hansgirg in Foslie, 1890. p. 155 ; Col- lins, igoSa, p. 155. Cells 4-6 p. diam., united in colonies of 2-8 cells, envelop distinctly stratified ; forming greenish-yellow gelatinous masses in company with other minute algae, near high water mark. Me. Europe. A doubtful species ; possibly a state of Ulothrix or Urospora. 30. GLOIOCOCCUS A. Braun, 1851, p. 170. Cells globose, enclosed in greater or less number in an ample globular transparent gelatinous mass ; with bell-shaped chroma- tophore and one pyrenoid. Asexual reproduction by division of a cell into four daughter cells, by the formation of aplano- spores, and by the formation of biciliate zoospores, of two sizes. 310 TUFTS COLLEGE STUDIES, VOL. II, No. 3 G. MUCOSUS A. Braun, 1851, p. 170; P. B.-A., No. 1516; Sphaerocystis Schyoctcri Chodat, 1897, p. 292, PI. IX. Cells 6-10 p. diam., colonies 50-1200 ^, perfectly spherical and trans- parent. Common in plankton of quiet fresh water. Fig. 122. Me., Mass. Europe. 31. GLOEOTAENIUM Hansgirg, 1890, p. 10. Cells globose, subellipsoid, or flattened, united in flattened, rounded families of 2 or 4 cells, with wide and distinctly lamel- late gelatinous walls ; chromatophore a somewhat curved disk, with no pyrenoid ; each family encircled by one or more dark- colored, opaque rings. L/ittle is known in regard to the reproduction in this genus, but it is probably, similar to that in Gheocystis ; the only notice- able difference between the two genera is found in the peculiar dark bands, whose nature is imperfectly known. Only one species. G. L,OITLESBERGERIANUM Hansgirg, 1890, p. 10 ; G. S. \Vest, 1905, p. 288, PI. CCCCLX1V, figs. 22 and 23. Cells 15-24X18-21 /A, united in 2 or 4-celled families; in 2-celled families, including teguments, 42-70X28-40 yu., 24-30 /u, thick ; in 4-celled families 60-80X40-60 /x, 30-40 /u thick ; 2-celled family encircled by one opaque band, 10-30 /j. wide ; 4-celled family by two such bands, intersecting on the flat side, and appearing cruciform seen from that side. In still water among other algae. Fig. 109. Trinidad. Europe. 32. PALMODICTYON Kiitzing, 1845, p. 155. Cells similar to those of Gloeocystis ; families of 1-3 genera- tions included in a wide, gelatinous wall ; combined into a gelat- inous, subcylindrical thallus, more or less branching and anas- tomosing ; reproduction by akinetes. Differs from Gloeocystis by the combination of the families into a gelatinous thallus of definite shape. P. VIRIDE Kiitzing, 1845, p. 155; West, 1904, p. 247, fig. 115. Cells 5-9 fj. diam., families up to 50/11 diam.; thallus i- several families \vide, up to 2 mm. long, branching and anasto- mosing freely, the outer layer often more or less reddish. Fig. 107. Mass. Europe. Family 7. HERPOSTEIRACEAE. Vegetative characters and asexual reproduction as in the Chaetophoraceae ; sexual reproduction by autheridia and oogonia transformed from vegetative cells ; oospore spherical, THE GREEN ALGAE OF NORTH AMERICA 311 large, with four cilia, which disappear before fertilization by the smaller, pyriform, 4-ciliate spermatozoids. Only one genus. HERPOSTEIRON Nageli in Kiitzing, 1849, p. 424. Frond microscopic, epiphytic, composed of simple or irregu- larly branched filaments ; cells bearing on the upper surface long, hyaline, inarticulate setae, with bulbous base but no sheath ; chromatophore parietal, with one or more pyrenoids. Asexual reproduction by 4-ciliate zoospores with red stigma, 1-4 in a cell ; sexual reproduction by the union of a spermato- zoid and an oospore, both 4-ciliate. The forms included under Herpostciron and Chactosphaoidiuni have all been included by authors under Aphanochaete, a generic name which apparently must be given up. Detailed reasons for this, as well as an account of the confusion in specific nomen- clature, will be found under Herposteiron in Hazen, 1902. KEY TO THE SPECIES OF HERPOSTEIRON. i. Cells usually subglobose, 5-10 M diam. i. H. confervicola. i. Cells usually subcylindrical, 4-6 fj. diatn. 2. H. vermiculoides. 1. H. coNFERviCOivA Nageli in Kiitzing, 1849, p. 424; Hazen, 1902, p. 230, PI. XL,II, figs. 5-7 ; Aphanochaete repens Wolle, 1887, p. 119, PI. CV, fig. 8; P. B.-A., No. 762. Creep- ing on various fresh water algae, filaments irregular!}- torulose ; cells subglobose to nearly cylindrical ; setae more or less fre- quent, about 3-4 /A diam. at base, very slender above, up to 200 fj. long. Fig. 116. Greenland, Vt. to N. Y.,, Cal. Europe. Probably not uncommon, but visible only on microscopic ex- amination of the host. The setae are not as uniformly produced as in Bolbocoleon and Chaetosphaeridium ; often only a small pro- portion of the cells are provided with them. 2. H. vermiculoides (Wolle) nov. comb.; Aphanochaete vermiculoides Wolle, 1887, p. 119, PI. CV, figs. 9 and 10 ; P. B.-A., No. 161. Cells 4-6 ^ diam., about as long as broad, more or less rounded, single or united in filaments, creeping on larger algae, or attached at two or more points, arched between ; setae few or many, seldom over 50 ^ long, with ellipsoidal base, one, rarely two or three from a cell, often absent. On Zygncma, Hyalotheca, etc. Conn., Pa. Nothing being known of the reproduction, the position of this plant is doubtful. The shape of the filaments is singular, often reminding one of a canker worm or measuring worm in motion. Apparently the filament, attached in two places, grows so 312 TUFTS COLLEGE STUDIES, VOL. II, No. 3 rapidly between these points that it forms an arch. Wolle's figure is unsatisfactorj', giving no idea of the form of the cells or of the setae, and not showing the manner in which the filaments encircle the host. Family 8. COLEOCHAETACEAE. Frond consisting of dichotouiously branched, monosiphonous filaments ; all prostrate on the " substratum, or with erect branches, branches distinct or laterally united to form a disk, or a pulvinate mass ; growth by division of terminal cells only ; cells uninucleate, with a parietal chromatophore, covering nearly all the cell wall and one pyrenoid, often producing slender, sheathed setae ; asexual reproduction by biciliate zo- ospores \vithout stigma, produced one in a cell, escaping by an opening in the wall, and germinating directly ; sexual repro- duction by oogonia and antheridia, produced in some species on the same individual, in some species on separate individuals ; autheridia formed by the division of vegetative cells, or by outgrowths from them, producing each one spherical, biciliate spermatozoid, released by the dissolving of the cell wall ; oogoniurn formed of the terminal cell of a branch, which en- larges and at the same time sends out a tubular prolonga- tion ; after fertilization by the spermatozoid this is closed by a partition at its base, branches in some species grow- ing out from the cell below the oogonium or the neighboring cells, and forming a more or less complete cellular coating to it, becoming red or red-brown. The oospore w7ith its coating rests for a long period, then the spore divides and increases in size, breaking through and throwing off more or less completely the coating, and from each cell is produced a zoospore, which ger- minates and produces the ordinary plant. Only one genus. COLEOCHAETE Brebisson, 1844, p. 29. Characters of the Family. This genus represents the highest type of fructification among the green algae, showing a considerable likeness to some of the lower forms of mosses, and possibly also an approach to some of the Florideae. The fronds of the various species form small, bright green disks or cushions on fresh water plants or other submerged objects. KEY TO THE SPECIES OE COLEOCHAETE. I. Forming gelatinous cushion-like masses. 6. i. Forming monostroinatic expansions. 2. 2. Filaments more or less distinctly radiate. 3. 2. Filaments spreading irregularly. 5. THE GREEN ALGAE OF NORTH AMERICA 313 3. Filaments laterally united. 4. 3. Filaments free. i. C. soluta. 4. Disk somewhat irregular in outline ; cells usually 25 /j. -wide or more. 4. C. scutata. 4. Disk regularly orbicular; cells seldom over 15 M diam. 5. C. orbicularis. 5. Epiphytic. 2. C. irregularis. 5. Endophytic. 3. C. Nitellarum. 6. Forming uniformly rounded masses ; filaments radiating from the center. 6. C. pulvinata, 6. Masses irregular ; filaments with no common center. 7. C. divergens. 1. C. SOLUTA (Breb.) Pringsheim, 1860, p. 6, PI. I, figs. 2 and 3 ; PL IV, figs, i and 2 ; Wolle, 1887, p. 64, PI. LXXII, figs. 1-7. Filaments branching, radiating from a common center, prostrate, not laterally united ; vegetative cells 12-25 /* diam., 2-3 diam. long; oogonia at first lageniform, then glo- bose, corticated, up to 200 //. diam., including cortex; oospore 100-150 /A diam. ; antheridia flask-shaped, about 17 ^ diam. Mass.,- N. J. Europe. 2. C. IRREGULARIS Priiigsheim, 1860, p. n, PL I, fig. 6; PL VI, figs. 3-9; Wolle, 1887, p. 65, PL LXXII, figs. 15-16. Filaments prostrate or decumbent, free or more or less united, quite irregular, not forming a disk ; cells quadrangular or polygonal, up to 25 //. diam., 1-172 diam. long; oogonia ovoid, either quite naked or somewhat corticated above, about 120X65 ju, ; antheridia? Pa., N. J. Europe. The only species with regular outline to the frond, but fila- ments not laterally united. 3. C. NiTELLARUM Jost, 1895, p. 434, PL XXXIV; C. ir- regularis P. B.-A., No. 974, not Pringsheim. Fronds endophytic in cell wall of Nitdla or Chara ; filaments simple or branched, more or less united to form a membranous expansion ; cells very irregular in outline, much flattened; no erect branches; setae penetrating the wall of the host and projecting externally ; oogonia spherical or flattened, more or less corticated above ; antheridia small cells cut off from the vegetative cells, usually a number together. Mass., N. Y., Neb., Mexico. Europe, So. America. Much resembling C. irregularis in general characters, except as modified by the peculiar habitat. Probably all reports of C. irregularis on Chara or Nitella refer to this species ; it wras dis- tributed under the name of C. irregularis in P. B.-A., No. 974. 314 TUFTS COLLEGE STUDIES, VOL. II, No. 3 4. C. SCUTATA Brebisson, 1844, p. 29, PL II, figs. 1-7 ; Rab- enhorst, Algen, No. 1126 ; Wolle, 1887, p. 64, PI. L.XXII, figs. 8- 13. Dioecious; frond orbicular, subparenchymatous, monostro- matic, composed of laterally united, branching filaments, radiat- ing from a center; cells quadrangular, 25-45 /u. diarn., 1-3 diani. long ; oogonia subglobose, naked below, corticated above, 140- i6oX 1 20 p.; antheridia produced 4 from the division of a vege- tative cell. Mass., N. Y., N. J., Neb., Colo. Europe, Asia, So. America, New Zealand. Distinguished from all but C. orbicularis by the continuous, monostromatic frond. 5. C. ORBICULARIS Pringsheim, 1860, p. n, PI. I, fig. 5 ; PL III, figs. 6 and 7 ; PL VI, figs, i and 2 ; Wolle, 1887, p. 64, PL LXXII, fig. 14. Frond orbicular, parenchymatous, mono- stromatic, composed of laterally united, branching filaments; cells oblong, quadrangular or polygonal, 8-16 ^ diam., about 2 diam. long; oogonia ovoid, 60-85X50-65 /*, naked below, more or less corticated above ; antheridia not known. Mass., N. J., Neb. Europe, New Zealand, Hawaii. Closely resembling C. scutata, but more regular in outline, and with smaller cells ; if antheridia should be found similar to those of C. scutata, it might be treated as a variety of the latter. 6. C. PULVINATA A. Braun in Kiitzing, 1849, p. 425; 1855, PL L-XXXIX, fig. 3; Wolle, 1887, p. 64; P. B.-A., No. 75. Monoecious ; frond pulvinate, gelatinous, composed of branch- ing filaments, radiating from a common center ; cells 20-40 ^ diam., 1^-2 diam. long; oogonia at first lageniform, globose when mature, .corticated, about 150 /A diam., including cortex; oospore iio^i diam.; antheridia flask-shaped, sessile, near the oogonia, 17 ^ diam., 2% diam. long. Mass., Pa., Alaska. Europe. Easily distinguished from other species by the cushion-like, not disk-shaped frond, formed of regularly radiating filaments. 7. C. DIVERGENS Pringsheim, 1860, p. 5, PL I, fig. i ; PL II, fig. 2. Monoecious; frond pulvinate, gelatinous, composed of branching filaments, with no definite center ; cells about 25 p. diam., 1-3 diam. long; oogonia including cortex up to 135 p diam. ; oospore to 95 /A. Fig. 1 10. These dimensions are for the type, which has not yet been noted in America ; we have Var. MINOR Hansgirg, 1886, p. 39; P. B.-A., No. 1331. Cells 12-18 /j. diam., 1-2^3 diam. long; oogonia 60-80 /u,, oospore 50- 70 /A. On Batrachospcrmnm and other algae. N. H. Europe. THE GREEN ALGAE OF NORTH AMERICA 315 The pulvinate thallus distinguishes this species from all others except C. pnhinata ; the absence of a common center for the filaments from the latter. Family 9. TRENTEPOHLJACEAE. Filaments branched, free or united into a membrane, cells uni- or multinucleate, chromatophore generall)7 band-shape, sometimes breaking up into small disks, without pyrenoid ; chlorophyll masked by haematochrome, coloring the cells yellowish-, brick-, or brown-red ; asexual reproduction by bicili- ate zoospores, formed in sporangia borne on geniculate or hooked cells ; the sporangia usually thrown off whole, the zoospores emitted only when the sporangia are moistened ; sexual reproduction by biciliate gametes, formed in sporangia terminal on or intercalary in the vegetative filaments ; these gametes often germinating without copulation. Aerial algae, with special adaptations to this mode of life. KEY TO THE GENERA OF TRENTEPOHLIACEAE. i. Basal layer a well developed disk ; erect filaments uubranched. 3. CEPHALEUROS. i. Filaments of basal layer not forming a disk ; erect filaments usually branched. 2. 2. Filaments often bearing inarticulate setae. 2. NYLANDERA. 2. Filaments not setiferous. i. TRENTEPOHI.IA. i. TRENTEPOHLIA Martius, 1817, p. 351. Basal filaments decumbent, producing erect filaments, simple or branched, parallel or irregular, cylindrical to moniliform, colored yellowish to red with haematochrome in the living plant, fading when dried ; often with an agreeable violet odor ; cells cylindrical to spherical, with band-shaped or broken chro- matophore and no pyrenoid ; asexual reproduction by biciliate zoospores, in sporangia borne on special hooked or curved cells ; sexual reproduction by biciliate gametes in gametangia trans- formed from vegetative cells, lateral, terminal, or intercalary, spherical or ellipsoid. A genus of terrestrial algae, forming matted layers on rocks, and on leaves and bark of trees. They range from arctic or high mountain regions to the tropics ; most of the species are very variable, and many species have been described based on charac- ters of little permanence ; our species are here arranged after Hariot, 1889-90, quite a number of species before generally rec- ognized being given as synonyms or varieties. A curious adap- 316 TUFTS COLLEGE STUDIES, VOL. II, No. 3 tation to the terrestrial habit of the genus is found in the fact that the ripe sporangia frequently are cast off from the frond entire, and emit the zoospores only when they fall into water, or are wet with dew or rain. The terrestrial habit makes the species of Trentepohlia very accessible to lichen-forming fungi, and in many cases it is rather an exception to find a plant not at all lichenized. KEY TO THE SPECIES OF TRENTEPOHLIA. i. Cells cylindrical. 2. i. Cells roundish, ellipsoid or fusiform. 7. 2. Sporangia scattered or in series. 3. 2. Sporangia in a glomerule or raceme. 6. 3. Filaments subsimple, tapering, acute. 4. T. effiisa. 3. Filaments branching, not tapering nor acute. 4. 4. Filaments 4-10 /j. diam. 3. T. abictina. 4. Filaments 10-32 A diatu. 5. 5. Filaments usually 12-20 M, sometimes a little more or less. i. T. aiirea. 5. Filaments 28-32 M. 2. T. villosa. 6. Glornerule terminal. 5. T. arboruni. 6. Raceme short, lateral. 6. T. Wainoi, 7. Filaments 6-12 /u. 7. T. lagenifera. 7. Filaments 12-44 /*. 8. 8. Growing on rocks, rarely on mosses. 8. T. lolitfius. 8. Growing on bark of trees. 9. T. odorata. 8. Growing on lichens. 10. T.rigidnla. i. T. AUREA (L.) Martius, 1817, p. 351 ; Hariot, 1889-90, p. 7 ; P. B.-A., Nos. 569, uSS, 1376 ; Chroolcpns anrcnm Wolle, 1887, p. 121, PI. CXV, figs. 1-21. Color golden to orange, yellowish when dry ; basal filaments cylindrical or more or less torulose, erect filaments cylindrical or sometimes slightly con- stricted at the nodes, parallel or irregular, more or less branched, usually obtuse ; forming dense tufts or extended strata ; branches somewhat tapering; cells usually 12-20 ^ diam., but with ex- treme forms 8-30 ^ ; membrane either smooth or roughened with minute scales ; gametangia 20-38 /* diam., globose or ellip- soid, terminal or lateral, borne directly on the vegetative cells ; sporangia similar, on the special curved cells. An extremely variable species, inhabiting all parts of the world ; characterized by the C}Tlindrical, not mucronate filaments of moderate diameter, and by the solitary or seriate gametangia. In the typical form the membrane is usually smooth, and the gametangia scattered ; T. nncinata (Gobi) Hariot is a synonym. THE GREEN ALGAE OF NORTH AMERICA 317 Var. POiA'CARPA (Nees and Mont.) Harlot, 1889-90, p. 15; T. polycarpa, P. B.-A, No. 472 ; including T. Tucket manni Mont. Membrane usually scabrous, gametangia larger, 24-45 p., in long series ; both this and the following variety pass into the type continually. Texas, Cal. So. Amciica. Var. SUBSIMPLEX (Caspary) De Toni, 1889, p. 237 ; P. B.-A., No. 1377. Erect filaments simple or with one or two short branches. Cal. Europe. Var. Pittieri (De Wildeman) nov. comb.; T. Pitticn De Wildeman, 1894, p. 6. Filaments 18-25 ^ diam., smooth, cells 2-5 diam. long; gametangia globose or ovoid, 40 ^ diam., to 56 /u, long, borne at the extremity of branches 9-12 //, diam., cells about 4 diam. long ; tips of branches, and especially of the branches bearing gametangia, often coiling about other filaments of the frond ; when this occurs with the fertile branches, there ma}7 be an appearance of a dense fascicle of gametangia on the filament. On leaves of various plants. Costa Rica. The principal characters by which this could be distinguished from T. aiirea are the rather larger and longer cells, the larger gametangia, and the cirrhous branches ; but in view of the con- siderable range of forms included under the species, these char- acters do not seem sufficient to distinguish it. The gametangia are so designated from their form and position, the original de- scription designating them only as " zoosporanges." 2. T. VILLOSA (Kiitz.) Hariot, 1889-90, p. 18 ; Wittr. and Nordst., Alg. Exsicc., No. 1066. Erect filaments elongate, tufted, flexuous, branching, pellucid ; cells 28-30 p. diam., 2-2^ diam. long ; reproduction unknown. The type does not occur with us, but we have var. brachy- meris Hariot, cells 28-32 /u, diam., 48-52 p. long. Dominica, Guadeloupe, Mexico. Asia. The cells in the type are unusually long for this genus, but shorter in the variety ; the diameter is quite uniform and larger than all but quite exceptional forms of T. aurea. 3. T. ABIETINA (Flotow) Hansgirg, 1886, p. 86 ; Wittr. and Nordst., Alg. Exsicc., No. 917 ; Chroolepus abiciinum Kiitzing, 1854, PI. XCI, fig. 2. Forming reddish, more or less confluent tufts, becoming ashy when dry ; cells of basal layer more or less torulose, erect filaments cylindrical or in a fewr of the lower cells slightly torulose, 4-10 /u, diam., about 3 diam. long; terminal cell sometimes considerably longer ; gametangia on special cells, 318 TUFTS COLLEGE STUDIES, VOL. II, No. 3 but sometimes terminal ; sporangia on special cells, spherical or slightly ovoid, 12-20 /A diam. Canada, N. H., Vt. Europe. A northern species growing usually on coniferous trees, but it has been found on oaks in Europe. It is like the smallest forms of T. a urea, but the filaments are more delicate and flexu- ous ; the gametangia are smaller, and are liable to be found anywhere on either erect or basal filaments. 4. T. EFFUSA (Krempelhiiber) Hariot, 1889-90, p. 52, figs. 12 and 13; T. setifera P. B.-A., No. 117. Forming yellowish- brown patches, becoming whitish when dry ; filaments of basal layer cylindrical or more or less torulose ; erect filaments 120- 300 /A high, 6-10 /x diam. at the base, tapering to a point, usu- ally simple, but sometimes branched ; cells 18-28 yu, long ; game- tangia developed from cells of the basal layer or lowest cells of the erect filaments, spherical or ovoid, 16-20X22-30^. Conn. Asia, So. America. The tapering filaments seem to indicate a connection between this genus and the Chaetophoraceae ; we have no species for wrhich it is liable to be mistaken. 5. T. ARBORUM (Ag.) Hariot, 1889-90, p. 20, figs. 8 and 9 ; P. B.-A., No. 1522. Filaments tufted, elongate, branching, somewhat attenuate ; branches usually patent and somewhat more slender than the main filament; cells 16-28 ^ diam., 40- 60 n long ; gametangia usually terminal ; sporangia 2-7 to- gether, the branch terminating in a swollen cell, on which are borne several nearly empty curved cells, each bearing a spo- rangium, spherical or ellipsoid, 18-24X24-32 p. Jamaica, Guadeloupe. Asia, So. America, Australia. The vegetative filaments resemble T. aurea, but the arrange- ment of the sporangia is characteristic. 6. T. WAINOI Hariot, 1889-90, p. 19, figs. 6 and 7 ; P. B.-A., No. 1523. Tufts yellow-green, about ^2 cm. high; filaments cylindrical, 16-28 /j. diam., cells 2-4 diam. long, wall smooth and rather thin, branches more or less abundant, irregularly placed, terminal cell slightly attenuate. Gametangia (?) spherical, 28- 40 /x diam., in more or less close series along the filaments; zoosporangia (?) about 12 /x diam., borne terminally on short, lateral cells, or on the terminal cells of branches arising from this cell. Fig. 117. California, Jamaica. So. America. 7. T. LAGENIFERA (Hildebrandt) Wille, 1887, p. 427 ; P. B.-A., No. 1470; Chroolepus lageniferum Rabenhorst, 1868, p. 373, fig. 104. Frond orange to crimson; both basal and erect THE GREEN ALGAE OF NORTH AMERICA 319 filaments of more or less torulose cells, branching, cells 6-12 p. diam., 2-3 cliam. long ; gametangia lageniform to subspherical, lateral or terminal, sessile or pedicelled, 8-12 /u diam., 20 //. long. W. I., Cal. Europe, So. America. The peculiar " bottle-shaped " gametangia are the character- istic mark of this species. S. T. IOWTHUS (L,.) Wallroth, 1833, p. 151; Wittr. and Nordst., Alg. Exsicc., No. 921 ; Hariot, 1889-90, p. 26, fig. 14; Chroolcpits lolithus Wolle, 1887, p. 122, PL CXVI, figs. 9-12. Filaments forming a thinner or thicker stratum, color bright reel, becoming olive green in dnring ; with a distinct and pleas- ant odor of violets ; erect filaments straight, torulose, branching, branches curved, apparently dichotomous ; cells swollen at the middle, with constricted nodes, 14-35 ^ wide, 24-50 ^ long ; a few cells at the end of the filament or branch often cylindrical and more slender ; membrane thick, with striations and other markings ; gametangia lateral, intercalary or terminal ; spo- rangia round, 20-48 p. diam., or ovoid, 36-40X45-54 p. Me., Mass., N. H., Alaska, Cal. l-'.urope, Oceanica. A plant found in all parts of the world, but characteristic of high altitudes or latitudes ; it usually grows on rocks, but occasionally spreads to the mosses also growing on the rocks. 9. T. ODORATA (Wiggers) Wittrock, 1880, p. 16 ; Hariot, 1889-90, p. 29, fig. 16; Chroolepus odoratum Wolle, 1887, p. 122, PI. CXVI, fig. 6 ; C. nnibrimun Wolle, 1887, p. 123, in part, PI. CXVI, figs. 4 and 5. Filaments forming a more or less dense, brownish- to orange-red, sometimes pulverulent or to- mentose stratum, without sharp distinction between horizontal and erect 'portions, flexuous, with short branches, more or less torulose, cells rounded, ovoid, ellipsoid or almost cylindrical, 10-30 /A diam., 1-1^2 diam. long; membrane from thin to thick and lamellate ; gametaugia subspherical to ellipsoid, lateral, terminal, or intercalary ; 20-30 //. diam.; sporangia of same size. Canada, Me., N. H., Mass., N. Y., N. J., Fla., Va., St. Vin- cent, Cal. Europe, Asia. Var. UMBRINA (Kiitz.) Hariot, 1889-90, p. 36, fig. 17 ; T. um- brina var. quercina, P. B.-A., No. 662. Filaments irregular and irregularly branched, cells rather loosely united. A widely distributed and variable species, including a num- ber of species of various 'authors. Following Hariot we can distinguish a typical form, with cylindrical filaments mostly straight and parallel, and cells firmly united, and the following 320 TUFTS COLLEGE STUDIES, VOL, II, No. 3 varieties. All are found growing on bark of various trees, rarely on other objects. Var. BETULINA (Rab.) Hariot, 1889-90, p. 50; P. B.-A., No. 1378. Cells ellipsoid, thick-\valled, in fairly distinct filaments. Principally on birch trees. N. H. Europe. 10. T. RIGIDULA (Miill. Arg.) Hariot, 1889-90, p. 36, fig. 17 ; C/ii'oo/cpus umbrinum Wolle, 1887, p. 123, in part, PI. CXVI, figs. 1-3; C. rigidulum Wittr. and Nordst., Alg. Exsicc., No. 1422. Filaments reddish or yellowish, ascending, stiff, subdichotomously branched, torulose, branches elongate ; cells fusiform-ellipsoid, swollen, with strongly constricted nodes, membrane thin, at first smooth and pellucid, soon cov- ered with fine scales or fibrils ; cells 16-24 //, diam. at middle, 12-15 p. at nodes, 24-36 ^ long ; gametangia spherical, 30 /* diam. Cuba. Asia, New Zealand, So. America. A species of warm regions, always epiphytic on lichens, which may be attached either to rocks or to the bark of trees. It approaches some forms of T. odorata, but is more branched, with cells more moniliform, and with thinner membrane.* 2. NYLANDERA Hariot, 1890, p. 85. Structure as in Trentepohlia, but all or many of the cells bear- ing inarticulate setae. Only one species. N. TENTACULATA Hariot, 1889-90, p. 41, fig. 22. Tufts small, inconspicuous, brownish when dry ; prostrate filaments short, little branched, 12-15 P- diam., cells spherical-ellipsoid, somewhat torulose, 1-1^2 diam. long; each cell usually bearing on the upper surface one, rarely two or three, inarticulate setae, 4-5 n wide, up to 90 /u.long, with globose-capitate tip.. Fig. 114. On bark, So. Carolina. The setae clearly distinguish this species from Trentepohlia, and perhaps indicate an affinity with the Chaetophoraceae. 3. CEPHALEUROS Kunze in Fries, 1829, p. 327. Frond of a basal layer of branching filaments, in one or more strata, with simple erect filaments, terminating either in a hair, or in a sporangium or group of sporangia, sexual or asexual. Distinguished from Trentepohlia by the fuller development of the horizontal disk, the reduced development of the erect fila- ments and the presence of hairs. * Chroolepus monilifonne Nageli in Kiitzing, 1849, p. 895, is a lichen, fide Hariot, 1889-90, p. 48. Wolle's plant, 1887, p. 123, PI. CXV, figs. 30-33, appears to be the same. THE GREEN ALGAE OP NORTH AMERICA 321 C. MYCOIDEA Karsten, 1891, p. 64, PI. IV, fig. n ; PI. V, fig. i ; Mycoidea parasitica Cunningham, 1879, p. 312, Pis. XUI, XIvIII, at least in part; P. B.-A., No. 763. Frond of several layers, attached to the substratum by rhizoids, with a thin general cuticle ; hairs colored with haematochrome ; very variable in shape and size of cells, amount of hairs, etc. On leaves of various tropical and subtropical trees. Fig. 123. Jamaica . Tropics generally. Much confusion has prevailed as to this species, and the name here used ma}7 not be in strict accordance with the laws of nomenclature ; but it seems safe to use it, as less likely to cause confusion, and it does not involve adding a new binominal to the list, already uncomfortably long. Phyllactidium iropicum Mobius, iSSSa, p. 225, PI. VIII, figs. 1-15 ; Hansgirgict ftabelligera De Toni, 1889, p. 263, is a doubt- ful form, concerning which there have been somewhat contra- dictory reports by different writers ; it has been reported from Cuba and Porto Rico, and from most tropical countries. It is evidently nearly related to Ccphaleuros ; Karsten, 1891, p. 62, refers it, though with some doubts as to its validity, to the neighboring genus, Phycopeltis. Order V. SIPHONOCLADIALES. Fronds multicellular, usually more or less branched ; cells multi-, very rarely uninucleate, chromatophore net-shaped, or of numerous small disks. KEY TO THE FAMILIES OF SIPHONOCLADIALES. I. Filaments simple, unattached ; sexual reproduction by oospores and antheridia. 5. SPHAEROPLEACEAE. i. Filaments simple or branched ; sexual reproduction isogamous. 2. 2. Main axis distinct, of limited growth. 3. 2. Main axis usually indistinct ; all axes of unlimited growth. 4. . 3. Axis bearing whorls of branches of limited growth and of form dif- ferent from the axis. 4- DASYCLADACEAE. 3. Branches either similar to the axis, or forming a terminal tuft or membrane. 3. VALONIACEAE. 4. Zoospores and gametes produced in little changed vegetative cells. i. CLADOPHORACEAE. 4. Zoospores produced in distinct, ultimately detached sporangia. Shell boring algae. 2. GOMONTIACEAE. Family i. CLADOPHORACEAE. Frond of simple or branching, monosiphonous filaments, free or more or less united laterally ; cells multi-, rarely uninucleate, 322 TUFTS COLLEGE STUDIES, VOL. II, No. 3 with chromatophore net-form, or broken into many small por- tions, with many pyrenoids ; asexual reproduction by 4-ciliate zoospores (sometimes by biciliate?) and by akinetes ; sexual reproduction by biciliate gametes; zoospores and gametes formed in little changed vegetative cells. Marine and fresh water. KEY TO THE GENERA OF CLADOPHOR \CEAE. i. Filaments simple. 2. i. Filaments branched. 3. 2. Filaments firm,' stiff. 12. . 2. Filaments soft, flaccid. 12. HORMISCIA. 3. Branches free, not united to form a membrane or tissue. 4. 3. Branches united to form a membrane or tissue. 8. 4. Branches usually short, rhizoidal. 2. RHIZOCLONIUM. 4. Branches of successive orders, but of the same character. 5. 5. Partitions regularly at bases of branches. 6. 5. No partitions regularly at bases of branches. 5. CLADOPHOROPSIS. 6. Akinetes formed of swollen intercalary or terminal cells ; zo- ospores unknown. 6. PITHOPHORA. 6. Akinetes unusual, little differentiated; propagation by zoospores. 7- 7. Specialized hooked or rhizoidal branches present; cell division largely intercalary. 4. SPONGOMORPHA. 7. No specialized hooked or rhizoidal branches; cell division chiefly terminal. 3. CLADOPHORA. 8. Filaments united in one plane. 9. 8. Filaments united in all directions, forming a solid or spongy frond. ii. 9. Frond continuous. 7. ANADYOMENE. 9. Frond perforate. 10. 10. Small secondary cells formed in the spaces between the filament cells, leaving rounded openings. 9. CYSTODICTYON. 10. No such secondary cells ; openings angular. 8. MlCRODICTYON. ii. Frond a spongy mass of network. 10. BOODLEA. ii. Frond spherical, solid or hollow. ii. DICTYOSPHAERIA. 12. Filaments regularly cylindrical or clavate ; originally attached, sometimes later floating. i. CHAETOMORPHA. 12. Filaments usually more or less irregular ; not attached. 2. RHIZOCLONIUM. i. CHAETOMORPHA Kiitzing, 1845, p. 203. Frond of a single unbranched series of multiuucleate cells, all but the usually longer basal cell capable of division ; basal cell producing either a disk or more or less branched rhizoidal pro- THE GREEN ALGAE OF NORTH AMERICA 323 longations for the purpose of attachment ; frond always at- tached, or loosening and continuing in a free state ; membrane thick, firm, usually distinctly lamellate ; asexual reproduction by 4-ciliate zoospores, produced in little changed cells ; sexual reproduction by biciliate gametes. Marine, rarely fresh water. KEY TO THE SPECIES OF CHAETOMORPHA. i. Filaments 400-600 fj. diam. 2. i. Filaments less than 400 yU. diam. 4. 2. Filaments increasing noticeably in diameter from the base up. i. C. clavata. 2. Filaments of nearly uniform diameter except at the extreme base. 3- 3. Basal cell many times as long as any other ; a southern species. 3. C. antennina. 3. Basal cell only slightly longer than the others ; a northern species. 2. C. melagonium. 4. Filaments over 40 /u diam. 5. 4. Filaments not over 40 /j. diam. 7. 5. Cells 3-8 diam. long. 6. C. cannabina. 5. Cells not over 2 diam. long. 6. 6. Filaments 125-400, usually 200-250 AC diam., yellowish-green. 4. C, aerea. 6. Filaments 125-175 /J. diam., dark green ; a southern species. 5. C. brachygona. 7. Filaments attached by a small disk ; marine. 7. C, calif arnica. .7. Filaments attached by coralloid, pluricellular branches; fresh water. 8. C. chelonum. 1. C. CLAVATA (Ag.) Kiitzing, 1847, p. 166 ; Vickers, 1908, p. 17, PI. VII; P. B.-A., No. 371. Filaments erect, stiff, up to 60 cm. long, base 500-750 //, diam., gradually increasing to 1.5 mm. or more at the tip ; lower articulations 3-4 diam. long, those of the upper part about as long as broad, more or less moniliform, color deep green. Yar. TORTA Farlow, P. B.-A., No. 571. Fronds loose and curled, cells less moniliform than in the type, and not increas- ing in diameter upwards so noticeably. A tropical and subtropical species, found in W. I. and in southern California. In the latter region it occurs mostly as the variety, corresponding to the floating forms of other species of the genus. 2. C. MELAGONIUM (Web. and Mohr) Kiitzing, 1845, p. 204 ; Harvey, 1858, p. 85; Farlow, 1881, p. 46; P. B.-A., No. 412 (forma typica) ; No. 413 (forma ntpincola) ; Conferva melagonium 324 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Harvey, 1846-51, PI. XCIX.A. Filaments erect, coarse and wiry, dark glaucous green, 400-500 yu, diam. ; cells 1-2 diam. long. A common species from N. J. to Greenland, occurring also in Alaska ; two forms are found ; f. RUPINCOLA (Aresch.) Kjell- man, growing attached and erect, usually quite straight, in low- est rock pools, and below ; reaching the length of a meter in northern regions, seldom over a third of a meter on thfe New England coast ; f. TYPICA Kjellman, unattached, lying loose in the sublitoral zone, forming crisped and entangled masses about the roots of Laminaria, etc. ; the latter form has usually been known as P. Picquotiana Mont., but is now pretty generally rec- ognized as a form of the present species. It seems unnatural to give the name of forma typica to what is apparently a later stage of the plant, but the exigencies of nomenclature require it. There is considerable variation in the size of the filaments, especially in f. typica, and the slender forms, sometimes as low as 300 p. diam., are not always easy to distinguish from C. aerca ; but the greater rigidit)^ and the dark glaucous green color are usually sufficient marks. It is a favorite host for epiphytes, and the number of species found growing on it in arctic regions is quite large. 3. C. ANTENNINA (Bory) Kutzing, 1849, p. 379; Vickers, 1908, p. 17, PL VIII; Wittr. and Nordst., Alg. Exsicc., No. 1439 ; C. pacifica Kiitzing, 1849, p. 379. Filaments dark green, 45O-55O P- diam., erect, somewhat flexuous, stiff below, less so above; articulations 2-4 diam. long ; the lowest cell 8-50 diam. long. W. I., Atlantic and Pacific coasts of Mexico. Africa. In habit resembling C. mclagoninni f. rupincola ; distinguished by the longer cells and the very long basal cell, which tapers much at the base. C. mclagonium is an Arctic species, very luxuriant in Greenland, only much reduced forms being found south of Cape Cod ; C. antcnnina does not appear to go farther north than Cuba on the west and Morocco on the east side of the Atlantic. 4. C. AEREA (Dillw.) Kutzing, 1849, p. 379; Harvey, 1858, p. 86; Farlow, 1881, p. 46; P. B.-A., Nos. 76, 1526; Conferva brachyarthra Kutzing, 1845, p. 203 ; Conferva acrea Harvey, 1846-51, PI. XCIX.B. Filaments erect, yellowish-green, 125-400 ju, diam., cells about as long as broad, base of filament usually THE GREEN AL.GAE OF NORTH AMERICA 325 more slender than the upper part ; when producing spores the fertile cells are much inflated and nearly globular. Fig. 115. In upper literal, especially in rock pools, from Me. to W. I. and in Cal. In habit like C. melagonium^ but of .somewhat smaller diameter, lighter color and softer texture ; not firm enough to stand erect when taken from the water. Forma Linum (Fl. Dan.) nov. comb. ; Conferva Linnni Har- vey, 1846-51, PI. CL. A ; Chaetomorpha Li mi in Farlow, 1881, p. 47; P. B.-A., No. 22; C. siitoria Harvey, 1858, p. 87; C. Oliicvi Harvey, 1858, p. 86, PI. XLVI.D; C. longiarticitlata Harvey, 1858, p. 86, PI. XIvVI.E. Filaments unattached, prostrate, light green, rather stiff, diam. 200-250 /u., cells about as long as broad. Apparently bearing the same relation to t3rpical C. aerea as the loose form of C. indagonium does to the attached form. It occurs in great masses of curled and crisped filaments in warm shallow bays, at least from N. S. to W. I. 5. C. BRACHYGONA Harvey, 1858, p. 87, PI. XIvVI.A; P. B.-A., No. 622. Filaments free, rigid, curved and twisted, forming strata of some extent on rocks or among other algae ; cells 125-175 /j. diam., quite uniformly as long as broad, except just after dividing. Fla., W. I., Mexico. Usually found in entangled masses among other algae, in the same way as the more northern Rhizoclonium tortuosum , which has, however, more slender filaments and proportionally longer cells. Rhizocldnium capillare Vickers, 1905, p. 55, appears to belong here. 6. C. CANNABINA (Aresch.) Kjellman, 1889, p. 55 ; P. B.-A., No. 916. Filaments unattached, soft and rather delicate, 75-100 /u, diam., narrow and wide together in the same tuft, or even a single filament tapering from largest to smallest measurement ; cells pretty uniformly 500 to 600 /j. long, being from 3-8 diam.; color light green. Me., Alaska, Washington. Northern Europe. Usually occurring in tangled masses, distinguished from the other species of northern range by the combination of softer texture, longer cells, and light color. 7. C. CALIFORNICA Collins, P. B.-A., No. 664 ; 1906, p. 106. Filaments attached by a small disk, about 20 cm. long, straight or flexuous, of uniform diameter throughout, not contracted at the nodes, 20-40 /x diam., cells 1-2 times as long as the diam., rarely 3-4 times. In shallow sandy pools near high water mark, Southern California. 326 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The most slender erect marine species known, not likely to be mistaken for an}r other. 8. C. CHELONUM Collins, 1907, p. 198. Filaments erect, straight, 12-20 fj. diam. at the base, increasing to 35 /u, diam. above; lower cell up to 50 diam. long, following cells 5-10 diam., upper cells 2-3 diam.; wall thick ; attached by coralloid, pluricellular branches ; fertile upper cells moniliform to globu- lar, up to 50 fi diam., i-4-diam. long. Mich. The only fresh water Chactoinorpha known in America, and distinguished from all other species, fresh water or marine, by the pluricellular branches issuing from the base of the filament, which may form a dense, inextricable mass on the substratum, which in the original and so far only known station was the backs of living turtles. Doubtful species. C, saccata Kiitzing, 1849, p. 380. C, intestinalis Kiitzing, 1849, p. 380. C. media Kiitzing, 1849, p. 380. C. tcnuissima Crouan in Maze and Schramm, 1870-77, p. 51. 2. RHIZOCLONIUM Kiitzing, 1843, p. 261. Filaments usually prostrate, of a single series of multinucle- ate cells, with net-shaped chromatophore and several pyrenoids, unbranched or in some species wdth a few irregular branches similar to the axis, and with more or less numerous rhizoidal branches, mostly unicellular, but sometimes of several cells. Asexual reproduction by biciliate zoospores with stigma, escap- ing through an opening in the cell wall ; also by akinetes ; but in only a few species has either form of fructification been found. Common plants of fresh and salt water, often forming exten- sive mats in shallow7 water or on ground in the literal zone ; the filaments resembling those of Chaetomorpha, but less uniformly cylindrical, there being almost always more or less irregularity in the form of the cells. The short rhizoidal branches, when present, clearly characterize the genus, but they are not always developed, and when they are absent, the resemblance to Chaeto- morpha is deceptive. In the few species where there are branches other than rhizoidal, they are formed quite differently from those of Cladophora, the branch pushing the original fila- ment out of place, itself continuing in the original direction. THE GREEN AI P- 53) No. 1179, and Chaetomorpha submaiina Crouan, I.e., p. 52, No. 342, from authentic specimens, seem to belong under R. ripai'ium ; Chaetomorpha lanosa Crouan, I.e., p. 51, No. 251, is more slender, 10-15 P- diam., and seems to approach R. Kochi- anum Kiitzing. 4. R. TORTUOSUM Kiitzing, 1845, p. 206 ; Farlow, 1881, p. 49; P. B.-A., No. 23; Chaetomorpha tortuosa Harvey, 1858, p. 88, PI. XlyVI.B. Filaments dark green, 40-70 p. diam., cells 1-2 diam. long, forming curled and twisted masses in tide pools and similar localities. Common from Gaspe to N. Y. ; reported from W. I. ; Alaska to Washington. Europe. Found mostly in summer on exposed shores, where the dark green crisped masses are very common in the lower pools ; it is the Chaetomorpha tortuosa of Harvey, 1858, but hardl}' the species of that name in Hauck, 1885, p. 443. The type is without branches. Forma POLYRHIZUM Holden, P. B.-A, No. 625. With abun- dant rhizoidal branches, of one to several short cells, similar to THE GREEN ALGAE OF NORTH AMERICA 329 those of the main filaments, the terminal cell abruptly conical. Me., Conn. 5. R. KOCHIANUM Kiitzing, 1845, p. 206; Vickers, 1908, p. 1 8, PI. XI ; Le Jolis, Algues marines de Cherbourg, No. 236. Filaments simple, cells 12-14 /* diam., 1-2 diam. long. Form- ing masses of contorted filaments on other algae. Barbados. Europe. 6. R. KERNERI Stockmayer, 1890, p. 582; P. B.-A., No. 623; R. Kochianum Farlow, iSSi, p. 49. Filaments pale yellowish-green, cells 10-14 P- diam., 3-7 diam. long ; no branch- ing. Me. to Conn. This species and the preceding are of about the same diam- eter, differing chiefly in the length of the cells. R. Kerneri grows in masses, loose or mixed with other algae, in tide pools or below. 7. R. HIEROGLYPHICUM (Ag.) Kiitzing, 1845, p. 206; P. B.-A., Nos. 718, 1192 ; R. lacustre Kiitzing, 1849, p. 385 ; 1853, PL LXXII, fig. 4; R. antillamm Kiitzing, 1849, p. 384 ; R. lacustre forma americanum Wille, 1899, p. 149; P. B.-A., No. 624; R. hicroglyphicnin var. aniencanum Wolle, 1887, p. 144, PI. CXXI, figs. 31 and 32; Rabenhorst, Algen, No. 2496. Filaments not much curved or contorted, 10-25 ^ diam., 2-5, rarely 1-7 diam. long, cells sometimes inflated at the middle, and of larger diam. there than given above ; wall not over 2 // thick ; branches usually absent, when present, small, tuber- cular or rhizoidal, rarely partitioned off from the cell. Fig. 1 19. Mass., Conn., Pa., 111., Mo., Minn., Fla., W. I., Cal. Europe, Asia, So. America, N civ Zealand. A very common and variable species, including the greater part of the fresh water forms. Var. MACROMERES Wittrock in Wittr. and Nordst., Alg. Exsicc., No. 630; P. B.-A., Nos. 119, 1191. Cells 20-30 ^ diam., 5-12 diam. long. Mass., Conn., Cal. Europe Var. Hosfordii (Wolle) nov. comb.; R. Hosfordii Wolle, 1887, p. 145, PI. CXXII, figs. 13-16; P. B.-A., No. 719. Cells. 36-40 /A diam., 3-6 diam. long, membrane thick; branches short, rhizoidal. Mass., N. Y. Quite different from the ordinary form of R. hieroglyphicum, but connected by var. inacromeres. 8. R. CRISPUM Kiitzing, 1845, p. 206; 1853, PI. L-XXI, fig. i ; Filaments 12-22 ^ diam., usually much crisped, firm ; cells i- ij^, rarely 2 diam. long ; membrane thick, 3-4^ ; branches infre- quent, unicellular or continuous with the cell, acute. Me., N. J., Md. Europe. 330 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Distinguished from R. hieroglyphicum by the thick membrane, firmer substance, and short cells. 9. R. FONTANUM Kiitzing, 1843, p. 261 ; 1853, PL LXXIV ; R.fontinaleWolle, 1887, p. 144, PI. CXXI, figs. 22-25. Fila- ments 12-22 jU. diam., cells 2-4 diam. long, membrane thickish ; branches usually abundant, mostly pluricellular. Me., Mass., Pa., 111., Porto Rico. Europe. 10. R. HOOKERI Kiitzing, 1849, p. 383; 1853, PL L,XVII, fig. 3 ; Hohenacker, Meeresalgen, 'No. 477. Filaments stiff, usually 70 /A diam., sometimes up to 90 //.; cells 2-4 diam. long, wall thick, 4-io/x; branches sometimes few, sometimes many; often pluricellular, occasionally having branches of a second order. W. I. So. America, Africa, Asia. A stout species, approaching Cladophora in its characters. 11. R. CRASSIPELLITUM var. ROBUSTUM G. S. West, 1905, p. 283. Filaments crisped, occasionally ventricosely inflated, curved and genuflexed ; about 70 ^ diam., cells 1^2-2 diam. long, walls very thick and stratified, up to 13^; apical cells somewhat attenuate and rounded, basal cell often inflated and producing rhizoids ; no other branching. Forming mats on damp earth. W. I. R. crassipcllitum W. and G. S. West, 18973, p. 35, with fila- ments 33-43 M diam., wall 9-13 /j. thick, is found in W. Africa.* * W. and G. S. West, 1895, p. 265, PI. XIV, figs. 17-24, describe R. Berg- grcnianuin var. dominicense ; filaments densely intricate, slender, cells 9-10 fj. diam., 2-3 diam. long, wall usually thin, a large proportion of the cells with short, very obtuse, usually unicellular or continuous branches. In hot water stream in crater of volcano, Dominica. The typical R. Berggrenianum occurs in New Zealand, and is much like some forms of R. hieroglyphicum, but has akinetes 16-20 /* diam., 1-3 diam. long; it may be merely the akinete-producing form of R. hieroglyph iciiiu . West's plant is probably an abnormal form, due to the hot water, etc. ; as it has no akinetes, its connection with -R. Berggrenianum is doubtful. G. S. West, 1905, p. 283, reports from Barbados R. hieroglyphicum var. Kochianiiiu (Kiitz.) Stockmayer, giving the dimensions as diam. 23-29 fj., cells i,J'2-2 diam. long. This would seem to agree better with the type, as Stockmayer gives 12-13 M f°r the diameter of var. Kochianum. R. occidentale Kiitzing, 1853, P- 22> ?l. LXIX. fig. 5, from Trinidad, seems from plate and description to be hardly distinguishable from R. hieroglyphicum. R. hieroglyphicum var. atrobrunneum Tilden, 1898, p. 90, PI. VIII, figs. 14-17, from Yellowstone Park, hardly seems to have enough distinctness from the type to deserve a name. Four species in Wolle, 1887, must be considered doubtful ; R. stagnate, R. fluitans, R. Casparyi and R. majus. From the plate CXXI, figs. 26-28, R. flniian$ might be considered as a synonym of R. crispum Kiitz. ; but a specimen marked R. fluitans by Wolle proves to be Microspora ainocna (Kiitz.) Rab. If R. stagnate is the same as R. stagnant in Wolle n. sp., Raben- horst Algeu, No. 2577, it is probably a coarse short-celled form of R. h ieroglyph icu m . THE GREEN ALGAE OF NORTH AMERICA 331 3. CLADOPHORA Kiitzing, 1843, p. 262. Frond composed of filaments of a single series of cells, the filaments branching, usually abundantly ; branching lateral, but often coming to appear dichotomous in conseqence of the pushing aside of the original filament by the branch ; growth chiefly by division of the apical cell, subsequent division of cells being rather exceptional ; branches all of the same type ; cells multinucleate, the chromatophore either covering the cell wall, or forming a network on it, or in the form of numerous small disks ; pyrenoids several in a cell ; asexual reproduction by 4- ciliate zoospores ; sexual reproduction by biciliate gametes, uniting and germinating immediately ; also sometimes germi- nating without copulation. One of the largest genera of algae, the species abounding in fresh, brackish and salt water the world over ; between 300 and 400 species have been described ; many of them so insufficiently that they can hardly ever be recognized. There are few sharply marked characters for distinguishing the species, it being mostly a question of more or less in one respect or another. This is specially true of those inhabiting fresh water, of which an al- most endless list of species, varieties and forms have been named, many duplicating each other, many founded only on temporary stages and abnormal conditions ; a careful mono- graphing of the genus would be a most valuable contribution to botany, but an exceedingly difficult task. In the meantime we must be contented with recording such forms as seem fairly well marked, leaving it for the future to determine what are autono- mous species, what states and conditions. Some species of Cladophora appear to be annual, some, per- haps the larger number, are perennial, the frond dying down almost to the base, which persists as a prostrate matted mass of cells, swollen and filled with reserve material ; when new growth begins, the filaments issuing from the older cells, which cells may perhaps be considered as akinetes, are so distinct in char- acter that if occurring separately they would pass for quite dis- tinct species. Until recently there have been included under Cladophora the subgenera Acrosiphonia (or Spongomorpha) and Aegagropila ; they are now more frequently considered as sepa- rate genera ; while by some writers Acrosiphonia and Spongo- 332 TUFTS COLLEGE STUDIES, VOL. II, No. 3 morpha are separated, species with uninucleate cells being placed in the latter, those with multinucleate cells in the former ; both being distinguished from Cladophora by special- ized branches of a different type from the original normal fila- ment. This distinction is not here maintained, all species with the specialized branches being included under Spongomorpha t the older name of the two. No such distinction is possible be- tween Cladophora and Aegagropila, and there is quite a possi- bility that Aegagropila forms are often or always stages or con- ditions of true Cladophora species. Aegagropila is therefore not here maintained. It has not seemed practicable to arrange the species in sub- genera or sections ; so many species are imperfectly known that any arrangement of this sort would be untrustworthy and misleading. For the determination of a specimen the key will serve as well, while leaving open the question as to which of the characters there used should be regarded as fundamental for classification. In this key the marine and .fresh water species are given separately ; an arbitrary division, but as the key is only for the purpose of determination, and does not at- tempt to indicate affinities, this plan seems justified. The marine species are first given, beginning with the more delicate erect species, then the larger and c arser, and ending with prostrate and matted forms ; they are so varied that it is impos- sible to group them about any few centers ; by bearing in mind that everything here is relative, not positive, it is hoped that the key will be of use to students. The fresh water species follow, falling naturally into two groups ; one arranged about C . frada, the other about C. glomerata ; it may be that these two species should include the others, but for the present it is more convenient to keep them separate. KEY TO THE MARINE SPECIES OF CLADOPHORA. i. Plants with creeping, matted base. 2. i. Plants erect. ~6. 2. Lower part of filaments 300-350 /x diain. 41. C, intertexta. 2. L,ower part of filaments less than 300 M diarn. 3. 3. Erect branches subsimple, much smaller than prostrate filaments. 38. C. ffozl'ti. 3. No sharp distinction between different kinds of filaments. 4. THE GREEN ALGAE OP NORTH AMERICA 333 4. Cells cylindrical throughout. 37. C. Magdalenae. 4. Some cells ovoid or pyriform. 5. 5. Cells 40-70, rarely 100 ,u diam. 40. C. amphibia. 5. Cells 120-250 ,u diatn. 39. C. trichotoina. 6. Main filaments from 150 fj. up. 7. 6. Main filaments seldom reaching 150 M- 10. 7. I^ower cells 10 diatri. long or more. 8. 7. Lower cells less than 10 diam. long. u. 8. Di- or polychotoruous branching normally from every cell. 31. C. graininea. 8. {Several cells usually between successive branchings. 9. 9. Branching alternate or opposite, except ne"ar the base. 33. C. cat en if era. 9. Branching generally dichotomous throughout. 35. C. prolifera. 10. Cells generally with a sharp constriction near the base. 12. C. constricta. 10. Cells without regular constrictions. 20. u. Ramuli curved. 25. C. tnicrocladioides. ii. Ramuli straight or nearly so. 12. 12. Ramuli clustered. 13. 12. Ramuli not clustered. 14. 13. Ramuli long, slender, cylindrical or nearly so. 26. C. fascii'itlaris. 13. Rarnuli short, stout, with constricted nodes. 28. C. Hutc/iinsiae. 14. Diameter nearly the same in all parts of the frond. 36. C. fnlig'inosa. 14. Terminal divisions markedly smaller than main stems. 15. 15. Filaments cylindrical. 22. C. hirta. 15. Nodes more or less constricted. 16. 16. Cells about the same length in proportion to the diameter in all parts of the frond. 32. C. catenata. 16. Upper cells proportionally shorter than the lower. 17. 17. Ultimate rarnuli very short, often of a single cell; cells in rarnuli ovoid, 1-2 diam. long. 18. C. brachyclona. 17. Ultimate ramuli not extremely short. 18. 18. Branching patent, except at the extreme base. 15. C. crucigcra. 18. Branching generally erect. 19. 19. Ramuli not exceeding 60 /.i diam. 30. C. oroidea. 19. Ramuli 70-100 ju diam. 31. C. utriculosa. 20. Main filaments distinctly angled or flexuous. 21. 20. Main filaments straight or nearly so. 34. 2i. Ramuli in clusters at tips. 22. 21. Ramuli not distinctly clustered. 23. 334 TUFTS COLLEGE STUDIES, VOL. II, No. 3 22. Fronds always attached. 46. 22. Fronds floating, except in earliest stages. 16. C. cxpansa f. glomerata. 23. Fronds floating, except in earliest stages. 24. 23. Fronds always attached. 28. 24. Ramuli in long pectinate series at ends of filaments. 26. 24. Ramuli scattered. 25. 25. Main filaments 100-150 /u diam. 16. C. e.rpansa. 25. Main filaments 30-60 fj. diarn. 27. 26. Filaments 40-100 fj. diam. ; cells 4-8 diam. long. 21. C. gracilis v. radorum. 26. Filaments up to 160 /j. diam. ; cells 3-5 diam. long. 21. C. gracilis v. expansa. 27. Ramuli straight ; color light. n. C. flavescens. " 27. Ramuli curved ; color dark. 13. C. crispula. 28. Frond of a spongy texture. 14. C.flexuosa f. densa. 28. Frond not of a spongy texture. 29. 29. Ramuli short, acute, spine-like. 7. C. polyacantha. 29. Ramuli not spine-like. 30. 30. Articulations long, up to 20 diam. 3. C. Rudolphiana. 30. Articulations not over 8 diam. long. 31. 31. Ramuli long, in pectinate series at tips of branches. 32. 31. Ramuli not in pectinate series at tips of branches. 33. 32. Branching patent ; main filaments flexuous. 21. C. gracilis f . australis. 32. Branching erect ; main filaments angular. 21. C. gracilis. 32. Branching very erect ; fronds up to i meter long. 21. C. gracilis f. elongata. 33. Fronds light or pale green ; plant of exposed rocky shores, No. Atlantic and Pacific. 14. C.flexuosa. 33. Frond light yellow-green ; little known So. Atlantic species. 10. C. lutcola. 34. Ramuli curved. 35. 34. Ramuli straight or nearly so. 38. 35. Frond of a spongy texture. i. C. albida v. refracta. 35. Frond stiff and firm. 36. 36. Ramuli closely set throughout. 37. 36. Ramuli dense at tips only. 17. C. scitula. 37. Main branches 80 fj. diam. or more. 23. C. refracta. 37. Main branches not over 50 ^ diam. 24. C. Bertolonii v. hatnosa. 38. Branches opposite or whorled. 29. C. ntpestris. 38. Branches not opposite or whorled. 39. 39. Filaments not exceeding 30 M diarn. i. C. albida. 39. Filaments over 30 /j. diam. 40. THE GREEN ALGAE OF NORTH AMERICA 335 4O. Ramuli acute ; main filaments not over 60 diam. 2. C. glancescens. 41. 42. 45- 43- 44- 4. C. delicatula. C. brachyclados. 8. C. nitida. 5. C. virgatiila. 6. 40. Ramuli not acute. 41. Main branches virgate. 41. Branching chiefly dichotomous. 42. Cells of ramuli 1-2 diam. long. 42. Cells of ramuli 4 diam. long or more. 43. Main filaments about 50 u diam. 43. Main filaments 80 /x diam. or more. 44. Ramuli 20-30 /u diam. 44. Ramuli 32-36 jn. diam. 45. Branching continuously dichotomous, except as to ultimate ramuli. 9. C. Stiuipsoni. 45. Main branching dichotomous; lesser branches and ramuli dense, largely secund. 19. C. crystallina. 46. Ultimate ramuli short, stout. 27. C. laetevirens. « 46. Ultimate ramuli long, slender. 20. C. dalinatica. KEY TO THE FRESH WATER SPECIES OF CLADOPHORA. i. Fronds floating, except in the early stages. 2. i. Fronds permanently attached. 7. 2. Forming hard, globular masses. 52. C. holsatica. 2. Of no definite form. 3. 3. Main filaments stout, with short cells, bearing long, slender, secund ramuli. 50. C. secunda. 3. No sharp distinction between branches of different orders. 4. 4. Main filaments bent, cells ovoid or pyriform, branching patent. 47. C.fracta. 4. Main filaments straight or nearly so. 5. 5. Main filaments long, with few branches. 51. C. insignis. 5. Main filaments freely branching, branches with many ramuli. 6. 6. Ramuli mostly unicellular. 6. Ramuli pluricellular, long-celled. 7. Ramuli in dense terminal clusters. 7. Ramuli not in dense terminal clusters. S. Ramuli recurved. 8. Ramuli straight or slightly incurved 9. L/ower branching mostly dichotomous distance. 9. Branching mostly alternate ; branches not connate. 42. 10. Not over i cm. high ; fil. about 40 fj. diam. 53. 10. Larger, 10-40 cm. high ; fil. 45 n diam. or more, n. Main filaments 75-125 M diam.; ramuli 35-50 M- 45 ii. Main filaments 45-85 ,u diam ; ramuli 25-35 <"• 46. C. Kuetzingiana. 48. C. oligoclona. 49. C. crispata. 8. 10. 43. C. declinata. 9- branches connate for soirie 44. C. canalicnlaris. C. glomerata. C. nbcrriina. u. C. calli coma. 336 TUFTS COLLEGE STUDIES, VOL. II, No. 3 1. C. ALBIDA (Huds.) Kiitzing, 1843, p. 267; Harvey-, 1846-51, PI. CCLXXV; 1858, p. 80; Farlow, 1881, p. 51; P. B.-A., No. 1227. Fronds soft, dense, pale green, filaments 20-30 fji diam., cells 4-5 diani. long, delicate ; branching irregu- lar, ramuli long, patent, blunt. Southern New England, Southern Cal. Europe. The soft, spongy consistency and very slender filaments suf- ficiently distinguish the growing plant, and generally the dried specimen. Var. REFRACTA (Wyatt) Thuret in Lejolis, 1863, p. 60; P. B.-A., No. 720; C. rcfrada Harvey, 1846-51, PI. XXIV; 1858, p. 79. Upper branches and ramuli recurved; otherwise like the type. New Jersey to Maine. Europe. In habit quite different from the type, but not in dimensions, etc. It seems to be commoner than the type, and to extend farther north on this coast. It shades into the type, and older specimens are liable to be mistaken for slender forms of C. ftexuosa; in the growing plant the texture is sufficient for distinction, ex- cept from C.flcxuosa forma densa ; in this case the dimensions of cells must be depended' on, as also in distinguishing from forms of C. rcfrada. 2. C. GLAUCESCENS (Griff.) Harvey, 1846-51, PI. CXCVI ; 1858, p. 77; Farlow, iSSi, p. 52; P. B.-A., No. 817. Fronds 10-40 cm. long, glaucous or yellowish-green, loosely tufted, much branched, ending in long, erect, acute, alternate or some- times secund ramuli; cells at base 50-60 ^ diam., in ramuli 25-30 /A ; cells usually 4-6 diam. long, sometimes considerably longer. Florida to Labrador. Europe. A plant of the literal zone, and in the northern part of its range, a plant of spring .and early summer. It is common in warm upper pools, exposed to the full sunshine, the upper part of the tuft fading almost to white. It grows also in marsh pools and shallow bays, where the water is warm. 3. C. RUDOLPHIANA (Ag.) Harvey, 1846-51, PI. I.XXXVI ; 1858, p. So; Farlow, 1881, p. 54; P. B.-A., No. 267. Fronds loose, soft, yellowish-green, gelatinous, up to a meter in length ; main filaments 40-60 p, diam., branches alternate or opposite, patent, flexuous, ramuli secund, tapering, about 20 ^ diam., cells always much longer than broad, sometimes up to 20 diam. long. Kennebunk, Maine to New Jersey, and probably farther south. Europe. THE GREEN ALGAE OF NORTH AMERICA 337 A plant of the upper sublitoral zone, growing in warm, shal- low bays, often in large quantities. Apart from the microscopic characters, to which recourse must be had in mounted speci- mens, the growing plants can generally be distinguished from the nearest species, C. albida and C. gracilis, by the consistency of the frond. C. albida is soft and spongy ; C. Rudolphiana soft but not spongy ; C. gracilis, even in its most slender forms, has a certain harshness to the touch. 4. C. DEUCATULA Montague, 1850, p. 302 ; Kiitzing, 1856, PI. I, fig. 2. Loosely tufted, soft, dull green, about 10 cm. high; filaments 40-60 /x diani. below, 4-6 diam. long; loosely branching, branches virgate, erect ; ramuli in short secund series, seldom over 8 cells in length, cells '20-30 fj. diam., 1-2 diam. long ; joints somewhat constricted. Florida, Jamaica, Porto Rico, Cal. South America. A delicate plant varying in the amount of ramification, and especially as to the frequency of the ramuli. 5. C. VIRGATULA Grunow, 1867, p. 38. Fronds 7-10 cm. high, soft, pale green, virgate, with subsimple main stem, beset with long, erecto-patent, subsecund branches, issuing from almost every joint ; connate for a short distance. Ramuli simple or with a few subsecund ramelli ; cells of main axis 75-110 p. diam., 3-6 diam. long; of the ramuli 45-55 /"• diam., 3-4 diam. long; of the ramelli 32-36 p. diam., 2-3 diam. long; terminal cells subtorulose. Guadeloupe. The above is copied from Grunow's description ; the plant resembles C. delicatula, but is larger. 6. C. BRACHYCLADOS Montagne, i838a, p. 15, PI. IV, fig. 2 ; Harvey, 1858, p. Si. Filaments erect, 80-100 /u. diam., primary branches long, patent, with numerous appressed ramuli ; ulti- mate ramuli very numerous, very short, secundly pectinate, 30- 40 /u, diam.; cells in main filaments 5 diam. long, in ramuli 2 diam.; nodes contracted. Cuba. Resembling C. delicatula, but a larger plant, not so delicate, with joints more uniformly constricted ; C. virgatula also seems near it, but according to the description the latter has more abundant main branches and fewer ramuli. 7. C. POLYACANTHA Montagne, 1850, p. 302 ; C. flexuosa forma Floridana Collins, P. B.-A., No. 978. Tufts dull green, 10-20 cm. high; filaments dichotomous below, 50-80 /u. diam.; branches long, rather stiff, flexuous, usually with naked apex, elsewhere set with long similar branches, 30-50 /j. diam., and 338 TUFTS COLLEGE STUDIES, VOL. II, No. 3 with numerous short, acute, spine-like ramuli, 25-35 M diarn., of two or three cells each. On rocks exposed to the waves, Florida. So. America. Somewhat resembling C. delicatula, but stiffer, branches less erect, and usually more abundant ; ramuli more acute, and not so distinctly secund. 8. C. NITIDA Kiitzing, 1843, p. 269; C. trichocoma Kiitzing, 1854, PI- XXIX,fig. 2 ; Collins, 1901, p. 244. Fronds yellow- ish or whitish green, soft, dense, somewhat mucilaginous, usu- ally up to 10 cm. high, occasionally much more ; main filaments 50-100 /A diam., bearing more or less frequent straight, virgate branches, with alternate or secund, rarely opposite, erect branches of higher orders, and secund slender ramuli, 20-30 p. diam.; cells cylindrical, from 4-12 diam. long, usually over 6 diam. Jamaica, Bahama. Europe. The fronds of this species are soft and slippery, often forming long, skein-like masses, similar to some species of Rhizocloniinn . In the American specimens identified with this species, the fila- ments are more slender than in most European forms. In the north of Europe it seems to be stouter and harsher than with us ; but some Mediterranean forms are soft and nearly as slender as the plants from Jamaica. 9. C. STIMPSONI Harvey, 18593, p. 333; P. B.-A., No. 729. Fronds loosely tufted, up to 30 cm. high, light green, of delicate and silky texture ; filaments 100-150 /u, at base, tapering gradually upward, di- trichotomously divided, branches contin- uously but distantly forking, successively smaller, ultimate branches lateral, secundly pectinate with long ramuli, 20-25 M diam., with rounded or slightly pointed tips. Cells 5-8 diam. long, longest near the base. On shells, etc. Southern Califor- nia. Japan. A soft, delicate, silky plant, reminding one of the more slender forms of C. gracilis, but distinct in manner of branching, substance and cell dimensions. 10. C. LUTEOLA Harvey, 1858, p. Si. Fronds pale yellow- green, tufted, very slender, much branched, not matted ; very flexuous, with rounded angles ; branching irregular, frequently trichotomous ; ramuli secund or opposite, at the tip pecti- nate, somewhat corymbose and crowded ; cells cylindrical, about 60 fj. diam. in main branches, 35 fj. in ramuli, 6-8 diam. long. Key West, Fla., Cuba. 11. C. FLAVESCENS (Roth) Kiitzing, 1843, p. 267; Harvey, THE GREEN ALGAE OF NORTH AMERICA 339 1846-51, PL CCXCVIII ; C. fracta forma flavescens Collins, 1902, p. 124; P. B.-A., Nos. 1077, 1229. Filaments at first attached, later loose floating, 30-60 /j. diam., forking at wide angles, cells 6-10 diam. long; ramuli not much smaller, taper- ing but with blunt tips ; forming dense yellowish-green floating masses in high, warm pools. Mass, to N. Y. Europe, This form occurs in high rock pools, where the water is quite salt; it has generally been considered a form of C. fracta, but is a smaller plant, attached in early stages, and inhabits strictly salt water. 12. C. CONSTRICTA Collins, 1909, p. 19, PL L,XXVIII, figs. 4and5. Tuftsdense, up 10 cm. high, somewhat fastigiate ; main filaments up to 65 fj- diam., branches smaller, ultimate ramuli about 25 /j. diam.; cells 5-20 diam. long, mostly somewhat clavate, often with a distinct annular constriction about one diameter above the lower end. Branching mostly opposite be- low and often above, but also often lateral, the short ramuli some- what secund ; branches at first rather patent but soon curving upward ; apex of terminal cell shortly conical with rounded tip. In general appearance not unlike a small and dense form of C. gracilis such as is often seen in shallow pools on the north At- lantic coast, but the resemblance is merely external, the branch- ing being more like that of C. rupestris. The cells vary much in length, but average quite long and usually increase slightly in diameter from base to summit. In the older parts the branching is quite regularly opposite or apparently trichoto- mous. The branching is quite dense, the outline usually reg- ular. The constriction does not occur on all the cells, but is often very distinct, the diameter of the cell being reduced at this point to less than half the normal, the interior thickening of the cell walls contributing to this reduction ; a slight manifestation of a character that is quite important in some Valoniaceae. 13. C. CRISPULA Vickers, 1905, p. 56 ; 1908, p. 19, PL XVI. Forming dark green spongy masses of contorted fila- ments, 45-50 /x diam., twisted in rope-like tufts; branches alternate or opposite, near the tips somewhat secund, curved ; cells about 8 diam. long. Barbados. Resembling in habit a Chaetomorpha , but with genuine branching. 14. C. FLEXUOSA (Griff.) Harvey, 1846-51, PL CCCLJII; 1858, p. 78; Farlow, iSSi, p. 54; P. B.-A., Nos. 1076, 1527. 340 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Fronds 10-20 cm. high, light green; main filaments 80-120 /u, diam., regularly flexuous, with flexuous alternate branches, 40-80 p. diam., with alternate or secund, curved and sometimes refracted ramuli ; cells from 6 diam. long below to 2 in the ramuli. Newfoundland to Bermuda and Florida, Alaska. Europe. A plant of nearly the same range on the Atlantic as C. glau- cescens ; it will probably be found on the Pacific to the south of Alaska. It occurs in rock pools, but usually near low water mark, and generally in colder places than C. glancescens. It is a firmer plant, larger in all dimensions except total length of frond, and is distinctly flexuous throughout. On the other hand the larger forms of this species approach small forms of C. gracilis, C. hirta, and C. laetevirtns, and it is often difficult to draw the line. Typical C. gracitis has long secund ramuli pec- tinately arranged at the end of every branch ; C. hirta has rather shorter ramuli in secund series all along the filaments; C. laetevirens has short, stout ramuli in dense fascicles at the tip. By these characters normal forms can be distinguished without much difficulty. C.flexuosa Vickers, 1908, p. 19, PI. XV, is hardly our plant ; the figure is rather like a slender form of C. gradlis. Forma DENSA Collins, 1902, p. 121 ; P. B.-A., No. 979. Branching of all orders very dense ; texture of frond spongy. At lower limit of literal zone. Newport, R. I. Habit like C. albida, but form and dimensions of cells like C. flcxuosa . 15. C. CRUCIGERA Grunow, 1867, p. 38. Fronds stout, pale green, rather loose, sparingly dichotomously branched ; branches patent, connate for a short distance at the base ; ramuli scattered, short, of few cells, alternate or oftener oppo- site, very patent ; cells about 300 /u. diam. below, 6-8 diam. long ; ramuli 75-110 /*, 3-4 diam. long, somewhat constricted at the nodes. Guadeloupe. Grunow's description has been copied ; he considers this a very distinct species, not to be mistaken for anything else. 16. C. EXPANSA (Mert.) Kiitzing, 1853, PI- XCIX ; Farlow, iSSi, p. 55; P. B.-A., Nos. 121, 977, 1280. Fronds dull green, loosely branched, main branches 100-150 fj. diam., flexuous, with smaller, patent, secondary branches, divaricately divided ; THE GREEN ALGAE OF NORTH AMERICA 341 rarauli 40 /x diam., secund, blunt; cells 3-6 diam. long. In warm pools and lagoons. Newfoundland to New Jersey. Europe. Common in summer in marsh pools and lagoons where the temperature is high and the level varies little ; at first attached, it soon rises to the surface, and ultimately forms a dense felty coating, continuous over large stretches of water, usually mixed with Lyngbya aestuarii and species of Entcromorpha. It will probably be found to extend in both directions beyond the limits given. Reports of C.fracta from marine stations prob- ably should be referred to this species. Var. GLOMERATA Thuret in Le Jolis, 1863, p. 61 ; P. B.-A., No. 1027. Ramuli in closely set tufts. Long Island Sound. Europe. The tufted ramuli give quite a distinct appearance ; otherwise it is like the type. 17. C. SCITULA (Suhr) Kiitzing, 1849, p. 399; 1854, PI. XII, fig. i ; Conferva scitula Suhr, 1831, p. 685 ; 1834, PL II, fig. 2. Frond small, brownish-green, stiff, densely fascicled ; filaments erect, branching, branches erect, connate at the base, above recurved, with short, secund ramuli ; lower cells 75-110 /j. diam., 2-4 diam. long. W. I. The figure by Suhr shows a small, perhaps immature plant with a few simple, slightly recurved branches and many short, secund ramuli ; the figure by Kiitzing, apparently from an older plant, shows rather virgate main axes, densely set with some- what secund branches ; the ramuli at the ends of the branches arranged much as in Ectocarpus fascicidatus. The cells in the main axes are about 3 diam. long ; in the ramuli 1-2 diam. long ; the tips are blunt and rounded. The description above is from Kiitzing, and there is possibly a doubt as to the identity with Suhr's plant ; if they are not the same, Kiitzing's had better stand for the species, as Suhr's figures and descriptions are hardly sufficient. There is no recent record of it. 1 8. C. BRACHYCLONA Montagne in Kiitzing, 1849, p. 394 ; 1853, PL XCVI, fig. 2. Fronds loosely tufted, pale green or yellowish, 10-15 cm. high; filaments di- polychotomous, 150- 250 /j. diam., in main divisions; branches at first distant, then more abundant ; ramuli very short, often of a single cell, alter- nate, opposite or secund, 50-75 ft diam.; cells of main divisions 342 TUFTS COLLEGE STUDIES, VOL. II, No. 3 cylindrical, 4-6 diam. loug ; shorter iu the branches, with con- ' stricted joints; in the rarnuli ellipsoid, 1-2 diam. long. Ber- muda. Mediterranean. No authentic specimens have been accessible, but the Ber- muda plant agrees so well with Kiitzing's figure that the iden- tity seems fairly well assured. 19. C. CRYSTALLINA (Roth) Kiitzing, 1845, p. 213; 1854, PL XIX, fig. 2. Fronds yellowish or whitish-green, soft, glossy, 10-30 cm. high; filaments slightly matted, distantly di- trichotomously branched; main branches 80-140 ^ diam., taper- ing to 25-40 p. in the ramuli ; branching erect or patent ; upper ramuli sometimes whorled or alternately secund ; cells cylindri- cal, 4-12 diam. long. Mass., W. I. Europe. A quite variable plant, but usually marked by its light color and silky gloss, which latter has given the specific names crvs- tallina, scricca and nitidissima to various forms. The long cells, often as long in the ramuli as in the main filaments, are also characteristic. The plant distributed under this name as P. B.-A., No. 723, is probably not correctly determined. C. sericea Vickers, 1908, p. 18, PL XIV, may be a shorter jointed and divaricately branched form of this species, but has also con- siderable resemblance to the following. 20. C. DALMATICA Kiitzing, 1843, p. 268; Vickers, 1908, p. 19, PL XIV.B. Fronds up to 5 cm. high, light green ; main filaments 80-120 ^ diam., simple or distantly dichotomous below, trichotomous above, with many alternate or secund branches ; cells 3-6 diam. long ; ultimate ramuli corymbose, incurved, secund, 30-50 //. diam.; cells 1)^-3 diam. long, nodes contracted, membrane thickish. Barbados. Europe. 21. C. GRACILIS (Griff.) Kiitzing, 1845, p. 215; Harvey, 1846-51, PL XVIII ; 1858, p. 80; Farlow, 1881, p. 55 ; P. B.-A., Nos. 1528, 1529, not No. 724. Fronds usually not. over 30 cm. long, yellowish or glaucous green, somewhat harsh to the touch; main filaments up to 160 /u. diam., irregularly bent, branching at the angles ; the branches more slender, set at the tips with secund series of long, attenuate, acute ramuli, 40-60 p. diam. ; cells 3-5 diam. long throughout. Greenland to Key West. Europe. A variable species, passing into C. lactevircns, C. hirta, and C. flexuosa ; see under the last for special distinctions. It assumes various forms under different environment and at dif- ferent stages of growth, and until one is familiar with it, will THE GREEN ALGAE OF NORTH AMERICA 343 often be very puzzling. The angular main stem and the pecti- nate terminal ramuli are the only constant marks to distinguish it from other species of the same general dimensions. It seems to be common from Massachusetts to Nova Scotia, both on ex- posed shores and in bays ; more than most species of Cladophora it thrives in places where it is quite out of water at low tide. Several forms occurring on the New England coast have re- ceived names. Var. VADORUM (Aresch.) Collins, 1902, p. 122; C. gracilis var. tennis Farlow, 1881, p. 55 ; C. vadorum Wittr. and Nordst., Alg. Exsicc., Nos. 1045, 1046. Filaments more slender than in the type, 40-100 /a, cells 4-8 diam. long. Forming loose, floating masses in the sublitoral zone, N. S. to N. J. Europe. Forma ELONGATA Collins, 1902, p. 122 ; P. B.-A., No. 725. Frond stretching out on the surface of shallow water to a length of a meter or more ; very glaucous green ; branches distant and very erect. In shallow warm pools where there is a definite steady current ; coast of Maine. Forma EXPANSA Farlow, iSSi, p. 55, as variety; P. B.-A., No. 981. Frond soon detached, forming loose floating masses, irregularly branched. Tide pools, coast of Maine and Massa- chusetts. Forming floating masses, similar to C. cxpansa, but not so dense. Forma SUBFLEXUOSA Collins, P. B.-A., No. 1530. Fronds shorter than in the type, branching dense, branches flexuous. A somewhat reduced form of shallow rock pools in northern New England. This form appears to originate in pools where the water is shallow, and there is no current ; where the water is shallow and a current runs through when the tide is out, forma elongata is produced. Forma australis n. f. Filaments less sharply angular ; branches of all orders more patent. The common form south of Cape Cod ; the opposite extreme from forma elongata, but connected by every gradation. 22. C. HIRTA Kiitzing, 1845, p. 208; 1854, PI. I, fig. 2 ; P. B.-A., No. 726. Fronds 20-30 cm. high, stiff and harsh ; fila- ments 150-200 /j. diam. at base, dull green, much or little branched ; all set throughout or frequently with short, subacute, more or less secund ramuli ; cells 2-4 diam. long, rarely some- what more. In rather exposed places, Greenland to Long Island Sound, and probably extending farther south. Europe. 344 TUFTS COLLEGE STUDIES, VOL. II, No. 3 In dimensions and general form somewhat like coarse C. gracilis'Qi the northern t\'pe, but distinguished by ramuli gen- erally distributed over the filaments, not merely at the tips. The amount of ramification varies much ; the most characteris- tic forms have long, little branched filaments set with longer or shorter secund series of ramuli ; the much branched forms are less characteristic, and require more careful examination. 23. C. REFRACTA (Roth) Areschoug, Alg. Exsicc. Scand., No. 338; Farlow, iSSi, p. 52; P. B.-A., No. 573. Fronds tufted, glaucous or dull green, 10-20 cm. high ; filaments rather stiff, 100-120 fj. diarn. below, 40-50 /x in the ramuli ; cells 2-3 diam. long ; branches of all orders at first erect, then reflexed; ramuli often secund, blunt. N. S. to N. J. Europe. The regularly reflexed branches of all orders distinguish this from all our other species of the same range except some forms of C. fle.tuosa and C. a/bida var. refrada ; the former is a more open plant, with flexuous rather than refracted branches ; the latter has more slender filaments and softer substance. C. rc- fracta has a characteristic habit, hard to describe, but fairly rec- ognizable when once seen. For C. refrada Harvey, see C. a I bid a var. refrada. 24. C. BERTOLONII var. H AMOS A (Kiitz.) Ardissone, 1886, p. 242; C. hamosa Kiitz., 1854, PI. VIII, fig. 2. Tufts 3-10 cm. high, dark green; filaments rather stiff, 80-100 /A diam. in the main divisions, 25-30 /j. in the ramuli ; much branched, main divisions di-trichotomous, set with alternate, opposite or whorled branches, usually short, and with densely set, secund, recurved ramuli; cells 1^3-3 diam. long, rarely more; terminal cells rounded, not tapering. Cal. Mediterranean. The California plant seems to be more slender than the European, seldom exceeding 60 /u. in the main branches and 25 /u. in the ramuli. The dark color, short cylindrical cells and elegant feathery tips, with a long series of secund, usual!}' slightly recurved ramuli on the similarly recurved branch, are fairly clear characters. 25. C. MICROCLADIOIDES Collins, 1909, p. 17, PI. LXXVIII, figs. 2 and 3. Fronds more or less densely tufted, 10-20 cm. high ; filaments about 200 ^ diam. at base, cells 4-6 diam. long ; stiff, straight or flexuous, distantly di-trichotomous, branches simi- lar, erect or more or less recurved, bearing on the upper (inner) side numerous short branches, rarely with very short branches THE GREEN ALGAE OF NORTH AMERICA 345 opposite one or more of them ; this ramification continued, the ultimate ramuli of very few cells, 80-100 /x cliam., cells 1^-2% diam. long. Cal. A stout but graceful species, with a characteristic ramifica- tion like that of Microdadia borealis Ruprecht. There is consid- erable variation, according as the main divisions are straight or flexuous, the branches close or distant, erect or recurved ; but the peculiar symmetrical ramification will distinguish it from any other of our species. As many as four cells may sometimes be found issuing from the much widened top of a cell, all flabel- lately arranged in one plane. 26. C. FASCICULARIS (Mert.) Kiitzing, 1843, p. 268; P. B.-A., Nos. 122, 1228, 1472; Vickers, 1908, p. 18, PI. XIII; Conferva fasdcularis Montagne, 1839, p. 4, PI. VII, fig. i. Fronds elongate, up to 50 cm. long ; main filaments and princi- pal branches flexuous, sparingly alternately branched, the ends beset with rather long, pectinate, more or less densely fascicu- late ramuli; main filaments 200-250 //. diam., cells 2-4 diam. long; ramuli 80-120 t^ diam., cells usually 1-2 diam. long. Florida, W. I. So. America. A common and quite variable species, something of the range of variation being shown by the specimens distributed in P. B.-A. 27. C. LAETEVIRENS (Dillw.) Harvey, 1846-51, PI. CXC ; 1858, p. 82; Farlow, 1881, p. 53; Conferva glomerala Wyatt, Alg. Danm., No. 143. Filaments 50-150 ^ diam., rigid, yellow- green, much branched ; branches erect, often opposite ; ultimate ramuli short, obtuse or subacute, densely fastigiate at the tips of the branches ; fronds up to 20 cm. long ; cells in main branches 6 diam. long, in ramuli 3 diam. A stout and rather coarse species, best characterized by the dense tufts at the ends of the branches, formed of stout, blunt ramuli ; it grows at the lower limit of the literal or in the sub- litoral zone, and is not a common species. The reports of this species from the west coast are all doubtful. Me., Mass. 28. C. HUTCHINSIAE (Dillw.) Kiitzing, 1845, p. 210; Har- vey, 1846-51, PI. CXXIV ; Farlow, 1881, p. 53. Fronds glau- cous green, up to 40 cm. high ; filaments 120-300 ^ diam., stiff, flexuous, sparingly branched ; ramuli few, secund, blunt, with constricted nodes; cells 2-3 diam. long. Florida and W. I. to New Jersey ; Vancouver Island. Europe. 346 TUFTS COLLEGE STUDIES, VOL. II, No. 3 The largest species of the North Atlantic coast, not to be mis- taken for any other species occurring there. It has been re- ported from few localities,. but is likely to be found at various points south of Cape Cod, and on the west coast south of Vancouver. Var. DISTANS (Ag.) Kiitzing, 1849, p. 392 ; C. diffusa Harve}*, 1846-51, PI. CXXX; 1858, p. 83; Conferva diffusa Wyatt, Alg. Damn., No. 144. Main branches long, nearly bare of sec- ondary branches ; cells longer than in the type ; nodes not con- stricted. Mass, to New Jersey. Europe. Connected with the type by intermediate forms. 29. C. RUPESTRIS (Iy.) Kiitzing, 1843, p. 270; Harvey, 1846-51, PI. CLXXX ; 1858, p. 74; Farlow, rSSi, p. 51; P. B.-A., No. 728. Fronds densely tufted, dark green; fila- ments stiff, 150 p. diam. at the base, 70-80 ^ in the rarnuli ; cells 3-4 diam. long ; branches opposite or in whorls of four, erect ; ramuli short, blunt or subulate. Greenland to Gay Head, Mass. Europe. A distinct species, growing usually on rocks in the literal zone, especially in places covered by Fuel and other large algae ; when growing it is a rich dark green, but in drying the color becomes duller and the plant seems coarse : it seems to be in as good condition in winter as in summer, while most North- ern species of Cladophora are spring and summer plants. 30. C. OVOIDEA Kiitzing, 1843, p. 266; 1853, PI. XCII, fig. i. Fronds 5-15 cm. high, stiff, rather dull green ; filaments distantly dichotomous, 150-200 /x diam. below, branches becom- ing more lateral and secund above ; upper ramuli not over 60 p diam , tips rounded or slightly pointed ; cells in lower part cylindrical, 4-8 diam. long; above ovoid, 1^2-3 diam. long. Santa Cruz, Cal. and vicinity. Europe. This plant is often found in collections bearing the name of C. cartilaginca ; but that species is probably a Spongomorpha. 31. C. UTRICULOSA Kiitzing, 1843, p. 269 ; 1853, PI. XCIV, fig. i ; Wittr. and Nordst., Alg. Exsicc., No. 929. Fronds tufted, light or dull green, 10-20 cm. high ; filaments firm, sub- membranaceous, di- polychotomous, 100-250 p. diam. near base, in upper part set with lateral, often secund ramuli, 70-100 /u. diam. ; cells 6-8 diam. long below, 2-4 diam. above. Jamaica, Bahama, Porto Rico., etc. Europe, So. America. A species varying much in size, extent of branching, etc. THE GREEN ALGAE OF NORTH AMERICA 347 32. C. CATENATA (Ag.) Ardissone in Rabenhorst, Algen, No. 1293. Fronds densely tufted, dark green, stiff, up to 8 cm. high ; filaments much branched, di- trichotomous below, 200- 250 ,u. diam. ; 80-150 // in ramuli ; cells 3-6 diam. long, nodes constricted ; ramuli opposite, secund or irregularly placed, somewhat fasciculate; terminal cell usually obovoid. Jamaica. Europe . Found throughout the Mediterranean, but so far reported at only this one locality in America. Somewhat like a more delicate C. prolifcra . 33. C. CATENIFERA Kutzing, 1849, p. 390; 1853, PI. LXXXIII, fig. i. Fronds stiff, cartilaginous or horn-like, flexuous, more or less densely branched, up to 50 cm. high ; main filaments 300-500 ^ diam. at base, alternately or sometimes oppositely branched, branches patent, the last series bearing opposite or alternate, more or less densely fasciculate ramuli, 100-225 /a, diam.; cells in main stem long, up to 20 diam., cylin- drical ; in branches S-io diam., slightly constricted at nodes; in ramuli 1^2-2 diam., oblong. Jamaica, Bermuda. Cape of Good Hope. A noble plant in its larger forms, resembling mostly C. pcllu- cida, under which name it has sometimes been reported. That species, however, is quite regularly di- polychotornous, branch- ing at the top of each cell. C. catenifcra varies much as to its rigidity or softness, and as to the density of the fascicles of ramuli ; but the other characters seem to be quite permanent. 34. C. GRAMINEA CollillS, 1909, p. 19, PI. LXXVIII, fig. 6. Loosely tufted, 10-15 cm- high, dark green, cartilaginous, dis- tantly di- trichotomous, all divisions erect ; main filaments about 300 i*. diam., ultimate divisions about 1 50 /x diam., tips blunt or slightly acute ; cells very long below, up to 30 diam., shorter above ; normally occupying the space from one forking to another ; ultimate branches 4-6 diam. long; cell walls usually strongly striate. Cal. Distinguished from all our other species by the long cells, each normally extending from one forking to the next ; in this it agrees with C. pcllucida (Huds.) Kiitz. of Europe, but in the latter there is more reduction of size in the successive orders of branches, the main filament being sometimes as large as 500 /u, diam., while .the ultimate ramuli are seldom over 50 /x, and are dense and more or less fasciculate. In C. grainim\i there is 34-8 TUFTS COLLEGE STUDIES, VOL. II, No. 3 comparatively little diminution in size, and the tips are loose and open. In C. pellucida the divisions of the di- or trichotomy are usually equal and develop equally ; in C. graiuinea one is often much reduced, sometimes only a singla cell. 35. C. PROLIFERA (Roth) Kiitzing, 1845, p. 207 ; 1853, PL LXXXII, fig. 3; Vickers, 1908, p. 18, PI. XII; Wittr. and Nordst., Alg. Exsicc., No. 1043. Fronds dense, dark green when growing, blackish when dried, up to 20 cm. high, rarely more ; filaments coarsely membranaceous or cartilaginous, 300-400 p. diam., di-trichotomous, divisions mostly erect, more frequent towards the somewhat fastigiate tips ; ramuli 130-200 [t. diam., blunt; cells up to 20 diam. in main filaments, much shorter in the branches, 4-6 diam. long in the ramuli. In lower litoral zone and in shallow water, Porto Rico, Barbados. Europe. A coarse, dark colored, rather unsightly plant, common in the Mediterranean, and generally in the warmer Atlantic. 36. C. FULIGINOSA Kiitzing, 1849, p. 415. Forming large, dark brownish-green tufts ; filaments hard, stiff, more or less densely matted, 150-160 /j. diam.; cells cylindrical, 5-10 diam. long ; the main axes long, set with short, blunt ramuli, often in secund series. Florida, W. I. This species was described from Cuban specimens, and has apparently never been since reported. The writer is indebted to Dr. Bornet for calling his attention to the fact that it is ap- parently the same as the Cladophora that, in combination with an endophytic fungus, Blodgcttia Bornet i Wright, 1881, p. 21, PI. II, figs. 1-4, makes up the Blodgettia confcrvoidcs Harvey, 1858, p. 48, PI. XlyV.C, and which was distributed under the last name as P. B.-A., No. 314. The hyphae of the fungus may possibly occur in connection with some other species of Clado- phora, but in all specimens observed the host agrees fairly well with the description of C. fnliginosa. 37. C. MAGDALENAE Harvey, 1846-51, PI. CCCL,Y.A ; Farlow, 1881, p. 56; P. B.-A., No. 572. Fronds short, coarse, dull green, 60-100 ^ diam., matted, procumbent, with patent, flexuous branches, bearing a few irregularly placed, curved ramuli; cells 2-4 diam. long. R. I. and Conn. Europe. A coarse, unsightly plant, creeping in tangled masses among other algae in the litoral zone, in late autumn and winter. Not THE GREEN ALGAE OF NORTH AMERICA 349 a well understood species, and perhaps it may some time prove to be a winter form of something else. 38. C. HOWEI Collins, 1909, p. 18, PI. LXXVIII, fig. i. Forming dense matted tufts, consisting of creeping basal fila- ments, with irregular cells about 150 p. diam., tapering to 75 ^ at the growing tips, cells 1-3 diam. long; from these basal fila- ments arise vertical filaments about 50 /u, diam. at base, tapering to 20-25 /j. at the rounded or slightly pointed tip ; cells about 5-6 diam. long at the base, up to 15-20 diam. long near the tip ; sparingly branched, branches erect or appressed, similar to the erect filaments. Bermuda. Forming a dense coating in tide pools, about i cm. high ; the base a mat of dark green, much branched, irregular fila- ments, from which arise the slender, slightly branched, long- jointed filaments, pale green under the microscope, yellow in the mass. This yellow color may not be a permanent charac- ter, as the same shade appears to be produced by local condi- tions in some algae normally green. The contorted, densely matted basal filaments indicate an affinity to the sub-genus Aegagropila, but there is no indication of a definite form to the whole mass. 39. C. TRICHOTOMA (Ag.) Kiitzing, 1849^.414; 1854, PI. IvXIV, fig. i; P. B.-A., No. 820; C. repcns, P. B.-A., No. 727, not of Harv.; C. colnmbiana Collins in Setchell and Gardner, 1903, p. 226. Forming light or bright green, densely pulvinate masses, 2-5 cm. high ; filaments procumbent at base, stiff, di- trichotomous with rather few short, alternate, rarely opposite branches, fastigiate at the tips ; cells 120-250 /x diam., 4-10 diam. long, nearly cylindrical below, above ovoid to pyriform ; the branches about the same diameter as the filament. Vancouver Island to Southern Cal. Europe. In habit like C. rcpcns, but of lighter or brighter color and larger cells. It grows in rock pools near high water mark, and has been found from Vancouver to the Mexican boundary. It seems impossible to draw7 any sharp line between C. trichotoma and C. columbiana ; the form distributed as C. rcpcns, P. B.-A., No. 727, differs so much from the Mediterranean plant that it seems best to include it under the present species. 40. C. AMPHIBIA Collins, 1907, p. 200; P. B.-A., No. 1284. Basal layer of densely branching prostrate filaments, cells cylin- drical, 40-70 fji diam. fcd 2-5 diam. long, or fusiform, 1-2 diam. 350 TUFTS COLLEGE STUDIES, VOL. II, No. 3 long, swollen to 100 /j. in the middle ; emitting erect filaments, cells 30-50 /a, diam., 4-8 diam. long, cylindrical or irregular, terminal cell obtuse or truncate ; slender descending rhizoids sometimes issuing from lower cells of erect filaments. Cal. A dull green, unattractive plant, growing near extreme high water mark, among Salicornict, in a salt marsh, and having much the habit of Vaucheria. 41. C. INTERTEXTA Collins, 1901, p. 243; P. B.-A., No. 8 1 8. Tufts densely matted, prostrate ; filaments 300-350 /A diam., creeping over shells and sand; cells i-i^ diam. long, rarely up to 3 diam.; bearing upright branches, about 200 yu. diam., simple or with a few short, secund raniuli ; terminal cells blunt. Jamaica. Forming dense, tangled masses in the bottom of pools ; the naked branches projecting, giving the whole the appearance of a tangled mass of Chactomorpha. 42. C. GLOMERATA (L.) Kiitzing, 1845, p. 212; P. B.-A., No. 1283. Fronds up to 30 cm. high, more or less densely branched below, branches more and more frequent towards the top, at last forming dense fascicles ; filaments cylindrical, 75- 100 fj- diam. below, 6-7 diam. long ; 35-50 ^ diam. in the ramuli, 3-6 diam. long ; ramuli not tapering, tips rounded ; fruiting cells terminal or subterminal. Fig. 124. An extremely variable species and not marked by any dis- tinct lines from the four following species. Specimens distrib- uted in P. B.-A., No. 1283, correspond fairly with the typical form ; the plant distributed as C. glomcrata, P. B.-A., No. 473, belongs rather in forma rivu/aris ; No. 278, Tilden, American Algae, is a quite elongate form ; a plant from the Mississippi River, Winona, Minn., conies nearer to the type than to any of the following varieties, and Tilden, American Algae, No. 35, C '. caUicoma, probably belongs here. Wolle gives few definite localities ; some specimens marked by him C. glomcrata have been examined, but they are very imperfect and uncharacter- istic. No. 32, Tilden, American Algae, is distributed as C. glomcrala var. fasciculata Rab. ; the only character- distin- guishing this from the type is found in the swollen terminal cells ; but as this appears to be due to the formation of spores, and is probably the same throughout the species, the varietal name seems unnecessary. Var. cla-c ce^s cylindrical, 5-20 diam. long, usually proportionally longer in the ramuli than in the main filaments ; ramuli not tapering, rounded at the end ; cell wall thin and delicate. The very long, slender filaments with erect branches gradu- ally decreasing in size, with long, delicate cells, make this a fairly distinct species. Many varieties have been described, but they are rather vague in their distinctions. Forma VITREA (Kiitz.) Rabenhorst, 1868, p. 336 ; Algen, No. 1529 ; Kiitzing, 1854, PI. XL,, fig. i. A delicate pale form, with long cells ; Iowa. The plant distributed under this name in Tilden, American Algae, No. 277, seems to be rather C. Kuetz-. ingiana Rab. As No. 2570, Rabenhorst, Algen, is distributed under the name of C. crispata Roth h. virescens Forma thcrmalis Briigg., a plant from Bethlehem, Pa., rather shorter-jointed than usual for this species. As P. B.-A., No. 1193, is distributed a very long and spar- ingly branched plant from California, under the name of C. cris- THE GREEN ALGAE OP NORTH AMERICA 355 pata forma subsimplcx Collins. It is quite close to forma longis- sima (Kiitz.) Rabenhorst, 1868, p. 337. This form seems to be quite common in California ; the fronds remaining attached to stones, etc. in running water until they have reached their full growth, sometimes as much as a meter ; the branching is rather distant, the ramuli are short, with cells 4-8 diam. long. 50. C. SECUNDA Kiitzing, 1849, p. 411; P. B.-A., No. 1230. Forming dense masses; main filaments elongate, sinu- ous, sparingly branched alternately or subdichotomously ; bear- ing long secund series of ramuli, normally one from each cell of the filament ; long below, becoming gradually shorter towards the tip ; cells in main filaments and branches 90-125 fj. diam., 3-5 diam long, cylindrical or somewhat contorted ; in ramuli 20-40 /u. diam., 4-8 diam long, cylindrical or slightly swollen ; ramuli tapering to the subacute tip. California. Europe. No authentic specimen of this species being accessible, there is naturally some doubt as to the identification ; the Californian plant formed floating masses in a watering trough at No. Berke- ley, Cal., while Kiitzing's plant, though included by him among the fresh wrater algae, was found by Suhr in brackish water in Denmark. The description agrees well with the plant, and there seems to be no other described species in which the latter could be included ; to avoid making a new species, the present name is applied. In our plant there is a remarkable contrast between the coarse cells of the large filaments and the delicate cells of the ramuli ; it seems like young plants of C. crispata growing out of old, battered stems of C.fracta, and emphasizes our lack of knowledge of any of these species, through all their life history. 51. C. INSIGNIS (Ag.) Kiitzing, 1845, p. 217; 1854, PL XXXVIII, fig. i ; P. B.-A., No. 868. Forming extensive strata ; filaments straight or nearly so, usually very little branched, 75-120 /A diam.; branches down to 40 /u, diam.; cells 4-6 diam. long, somewhat swollen. In quiet \vater, California. Europe. Fairly distinct by the stout, straight, little branched filaments. Our plant seems to belong to the type, but any of the numerous varieties may be expected. 52. C. HOLSATICA Kiitzing, 1849, p. 414; C. a eg agropUa P. B.-A., No. 164. Forming by the dense and irregular branch- 356 TUFTS COLLEGE STUDIES, VOL. II, No. 3 ing, spherical masses, 1-3 cm. diam., lying loose on the bottom, or slightly attached by rhizoidal growths ; filaments about 45 /* diam. at base, up to 90 /j. in the main branches, ramuli 45 p., terminal cells clavate or blunt-lanceolate, often swollen near the tip ; cells mostly somewhat larger at the top than at the base ; branches quite irregularly placed, densely packed. Mass. Europe. In the only reported American locality, this species was washed ashore in the form of small, hard, globular masses, each a densely branched individual. Other forms of the Aega- gropila type probably occur, but no definite reports are to be had. 53. C. UBERRIMA Lambert ms.; P. B. -A., No. 1531. Frond minute, seldom over i cm. high, attached below by short, irregular, branching filaments ; main filaments 30-50, rarely 60 fj. diam., cells 3-10 diam. long; densely branched, branches opposite or alternate, erect or patent, issuing from any part of a cell ; the first cross wall either at the base of a cell or higher up ; erect branches often connate with each other or with the main stem for some distance ; ultimate ramuli straight or curved, 15-20 fj. diam., cells 5-10 diam. long; terminal cell slightly at- tenuate, with rounded apex. Production of zoospores and gametes very abundant, in terminal or intercalary cells, in all parts of the frond ; new growth from cell below often passing through the empty sporangium. A rather anomalous species, presenting some remarkable peculiarities ; this notice is merely preliminary ; a detailed account of the plant is soon to be published by Professor Lam- bert, who has had it under culture at the Botanical Laboratory of Tufts College. Among the doubtful species of CladopJiora must be reckoned the following. C. trinitatis Kiitzing, 1849, p. 420. C. Morrisiac Harvey, 1858, p. 78, PI. XLV.B. Aegagropila Montagnci Kiitzing, 1849, p. 415 ; 1855, P- J4> PL LXV, fig. 2. Spongopsis saccata Kiitzing, 1849, p. 380; 1853, p. 17, PI. L, fig. i. 4. SPONGOMORPHA Kiitziug, 1843, p. 273. Fronds of branching, monosiphonous filaments, larger at the tip than below, terminal cell longer than other cells, intercalary THE GREEN ALGAE OF NORTH AMERICA 357 cell division general, cells other than terminal usually short ; special descending rhizoidal branches, or special spine-like or hooked branches present, more or less matting the tufts to- gether ; cells in one species uninucleate. Otherwise as in Cla- dophora. Marine. The special branches give this genus a higher rank than that of Cladophora, and the predominance of intercalary cell division also distinguishes it. The species are most abundant in arctic waters, not extending south beyond the temperate zone. The species from the Atlantic here included in Spongomorpha would be placed by Scandinavian authors under Acrosiphonia, follow- ing the monograph of that genus by Kjellman, 1893, except that if Wille, iSgga, is followed, the multinucleate species are in- cluded in Acrosiphonia, and Spongomorpha is used only for the uninucleate Cladophora lanosa. In Jonsson, 1904, the algae of East Greenland are thus divided, but the old specific names arcta and lanosa disappear entirely, Acrosiphonia incurva and Spongomorpha vernal is appearing instead. It is hard to see what principle justifies this. Spongomorpha dates to Kiitzing, 1843; Acrosiphonia to J. G. Agardh, 1846; the specific names incurva and vcrnalis are of Kjellman, 1893, while arcta dates from Dillwyn, 1809, and lanosa from Roth, 1806. KEY TO THE SPECIES OF SPONGOMORPHA. i. Spinous or hooked branches present. 2. i. Spinous or hooked branches wanting. 4. i 2. Branches not spinous ; tufts little matted. i. S. duriitsciila. 2. Branches spinous ; mature tufts densely matted. 3. 3. Filaments 100 /j. diam. at tip. 6. S. spinescens. 3. Filaments 200 i*. diam. at tip. 7- S. coalita. 4. Filaments 200-500 fj. diam. at tip. 2. 5". hystrix. 4. Filaments less than 150 /u diam. at tip. 5- 5. Main filaments and branches obtuse. 6. 5. Main filaments and branches blunt-pointed. 5. S. saxatilis. 6. Filaments 30-40 /m diam. 3- •$"• lanosa. 6. Filaments 60-100 /j. diam. 4- S. arcta. i. S. duriuscula (Rupr.) nov. comb. ; Cladophora alaskana Collins in Setchell and Gardner, 1903, p. 228; P. B.-A., No. 917. Tufts 15-25 cm. high, erect, main filaments firm, straight, with thick, striate walls, 200-250 /u, diam. below, 300 at tip; articulations >2-i>2 diam. long, 2-3 diam. at the blunt tips; branches similar, erect, scattered or in secund series of two or 358 TUFTS COLLEGE STUDIES, VOL. II, No. 3 more ; near the base of the tuft more slender, 150-200 p. diani., with thinner walls, not striate, with numerous short, patent or recurved ramuli, scattered or secund. On stony beaches, lower literal and upper sublitoral. Alaska. A coarse species, but not matted like most species of Spongo- morpha ; it might be a question whether it belongs in this genus or in Cladophora ; but the filaments usually larger at the tip, never tapering, the cells short below, longer above, indicate the present genus. Since the publication of Cladophora a/askana it has been possible to examine authentic specimens of Ruprecht's Conferva duriuscula, and there is no doubt of the identity ; Ruprecht's description, however, is so scanty that no decision was possible from it ; De Toni placing the species in Chacto- niorpha . 2. S. HYSTRIX Stromfelt, 1887, p. 54; Cladophora hystrix P. B.-A., No. 982. Fronds rich green, in rather dense tufts, filaments straight, very erect, except those at the base of the tuft, which are somewhat more open ; about 100-300 /A diam. at the base, 200-500 p. diam. at the tip ; cells up to 4 diam. long at the tip, J/2-I/-2 diam. long below ; rhizoidal branches fairly com- mon in the older parts, 40-70 /A diam., cells 3-10 diam. long. Resembling S. arcta, but stouter and with shorter cells; a distinctly arctic species, found on the Massachusetts coast only in a reduced form, while 6". cirda is practically the same in Greenland as in L,ong Island Sound. Three forms are reported from Greenland. Forma typica (Jonsson) uov. comb. ; Acrosiphonia hystrix forma typica Jonsson, 1903, p. 368. Fronds up to 15 cm. high, filaments 300-500 /j. diam., not much entangled. Forma Httoralis (Jonsson) nov. comb. ; Acrosiphonia hystrix forma Httoralis Jonsson, 1903, p. 370. Tufts 4-10 cm. high, filaments 200-300 p. diam., considerably entangled. Forma debilis (Rosenv.) nov. comb. ; Cladophora arcta forma dcbilis Rosenvinge, 1893, p. 908. Tufts not over 10 cm. high, with few long branches, but many short, subsimple, often secund branches, of about equal length. 3. S. LANOSA (Roth) Kiitzing, 1849, p. 420; Cladophora lanosa Harvey, 1846-51, PI. VI; 1858, p. 76; Farlow, iSSr, p. 51 ; P. B.-A., No. 661. Fronds fastigiate, erect, light green, not over 5 cm. high, 30-40 /j. diam., branches erect, usually arising some distance below top of cell ; cells uninucleate, 2-6 THE GREEN ALGAE OF NORTH AMERICA 359 diam. long, more or less matted at the base by descending rhizoidal filaments, slightly smaller than the main filaments. On various algae. Greenland to Conn. Europe. A spring plant, forming very regular rounded tufts on vari- ous algae, the tufts becoming detached as the plant matures. It is noteworthy as having only one nucleus to a cell, while as far as observed all other species of Spongomorpha and Clado- phora have normally two or more nuclei. It is possible that some of the Alaskan species may also be uninucleate, but no certainty can be had from dried specimens. On the other hand, single uninucleate cells are occasionally, though rarely, found in other species ; and as apart from this character this species is in everything conformable to Spongomorplia, it does not seem necessary to institute a separate genus for it. Var. UNCIAUS (Fl. Dan.) Kjellman, 1883, p. 306; Cladophora imdalis Harvey, 1846-51, PI. CCVII ; 1858, p. 77; C. lanosa var. undalis Farlow, iSSi, p. 51 ; P. B.-A., No. 77. Tufts ir- regular in outline, growing on rocks, not floating away when mature, but persistent in a coarse and faded state. Me. to Conn. Europe. 4. S. ARCTA (Dillw.) Kiitzing, 1849, p. 417; Cladophora arcta Harvey, 1846-51, PI. CXXXV ; 1858, p. 75; Farlow, iSSi, p. 50; P. B.-A., Nos. 224, 815. Fronds rich green, in dense fastigiate tufts, up to 15 cm. high; filaments erect, stiff, 60-100 ju. diam. at tips, cells 4-6 diam. -long ; below smaller, cells i Y-2. -3 diam. long ; much branched, branches erect or appressed, obtuse orclavate ; rhizoidal descending branches 40-60 /u, diam., cells 2-6 diam. long, firmly matting together the lower part of the tuft. On exposed rocky shores in spring. Greenland to N. J. ; Alaska to Wash. A common plant, the rounded rich green tufts being very handsome while the plant is young ; later it becomes coarse and faded.* Forma conglutinata nov. comb. ; Cladophora arcta forma conglutinata Collins in Setchell and Gardner, 1903, p. 225. Filaments adhering in pointed, Symploca-like tufts ; patent acute branches occasionally found at the base of older plants. Alaska to Wash. *Var. penidlliformis Foslie in Wittr. and Nordst., Alg. Exsicc., No. 613, a rather slender form with terminal sporangia, is doubtfully re- ported from Greenland, Roseuvinge, 1893, p. 908; Jonsson, 1904, p. 49- 360 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Forma PULVINATA Foslie, 1890, p. 130; Cladophora arcta forma pulvinata P. B.-A., No. 918. Filaments short, of uni- form length, forming level-topped pulvinate masses. Alaska. Northern Europe. 5. S. saxatilis (Rupr.) nov. comb. ; Cladophora saxatilis Setchell and Gardner, 1903, p. 223 ; P. B.-A., No. 921. Fronds dense but not much matted together; filaments 80-120 /* diam., about the same diam. throughout, cells below 1-3 diam. long, above 3-6 diam. ; terminal cell sometimes 10-12 diam. ; branching di- trichotomous, with occasional lateral branches, divisions erect, somewhat acute or tapering, but with rounded tip ; older parts with descending rhizoidal filaments, about half the diam. of the filaments from which they spring, and with longer cells, sometimes 10-12 diam. long. Alaska to Wash. Kamtschatka. Varying considerably in size of filaments, length of cells, erect or patent branches, but on the whole with longer cells than most of the species of Spongomorpha. The branches increase little if any in size towards the end, and the terminal cell is not sharply truncate. The four species of Ruprecht, 1856, Con- ferva Chamissonis, C. Mertensii, C. viminea and C. saxatilis, seem to be merely varieties, forms or states of growth of one species, C. saxatilis representing stouter or older forms, C. Cha- missonis more delicate ; the two other species range between, lyittle could be known from Ruprecht's short descriptions, but authentic specimens in Herb. Farlow justify the present arrangement. Var. Chamissonis (Rupr.) nov. comb. ; Cladophora Cha- missouis Harvey, 1858, p. 75 ; P. B.-A., No. 920. Filaments 40-60 /A diam., cells 3-4 diam. long, nodes constricted; cells slightly shorter towards the base. Alaska to Wash. Kamtschatka. Smaller and more delicate than the type, but not otherwise distinct. 6. S. SPINESCENS Kiitzing, 1849, p. 418; 1854, PI. L,XXV, fig. 2 ; Cladophora arcta var. centra/is P. B.-A., No. 721. Fila- ments about So p. below, zoo/xat tip ; cells 3/2-1 diam. long below, 2 diam. long at tip ; normal erect, somewhat obtuse branches abundant ; also patent and acute branches, either short and spine-like, or long, hooked, revolute and circinate, uniting the filaments into branching rope-like tufts ; descending rhizoidal branches less common. Fig. 126. Me. to Mass. ; Alaska. Northern Europe. THE GREEN ALGAE OF NORTH AMERICA 361 Often confused with .5*. arcta, which in its older stages is much matted ; but in that species the filaments are united by the descending rhizoidal branches only ; in 6". spinesccns chiefly by the hooked branches. 7. S. coalita (Rupr.) nov. comb. ; Cladophora coalita P. B.-A., No. 819; C. scopacformis Harvey, 1858, p. 75 ; P. B.-A., No. 922. Fronds at first loosely tufted, but soon forming dense, rope-like branching tufts, up to 30 cm. long ; at first bright, later dull or yellowish-green ; filaments 100-250 ^ diam. in the terminal cell ; branching dichotomous below, irregularly alter- nate above ; all branches of this class erect, with blunt or trun- cate ends ; also present, except in very young plants, abundant patent, tapering, very acute, hooked or circinate branches, by which all the older parts are densely matted together ; cells y$-i diam. long in the lower part of older plants, 2-3 diam. in younger plants, and even 6-10 diam. in the active terminal cell. Alaska to Cal. Kamtschatka. The hooked branches distinguish this species from all others except S. spinescens, which is a smaller plant, with filaments about half the size of those in .S. coalita. In the review of this group in Setchell and Gardner, 1903, p. 227, Cladophora coalita and C. scopacformis were considered distinct species, but on look- ing over material from various points, and collected at various seasons, it seems impossible to keep them separate. C. polaris Harvey would seem to be the very young plant, with normal erect branches only, and with texture delicate. When the plant has nearly reached its full growth, it is C. scopaeforuiis, with long, green, actively dividing terminal cell to each normal branch ; in the lower part of the filaments the cells are consid- erably shorter, and the walls cartilaginous ; hooked branches are plentiful. At a still later stage the terminal cells have ceased to grow at the tip as fast as new cells have been cut off below ; they are but little distinct from the other cells, either in length or texture. The division of the lower cells has gone on until most of them are shorter than their breadth ; hooked branches have been developed until the greater part of the plant is now shaggy with them. The plant is now typical Conferva coalita of Ruprecht. C. cartilaginca Ruprecht very likely should be here included; btit the description, 1856, p. 404, is hardly sufficient, and no authentic specimens are ac- 362 TUFTS COLLEGE STUDIES, VOL. II, No. 3 cessible. The specimens from Monterey, referred to Cladophora cartilaginea, Setchell and Gardner, 1903, prove to belong elsewhere. Spongomorpha rhizophora Kiitzing, 1849, p. 418 ; 18553, p. 16, PI. LXXVI, fig. 2, is a doubtful species. 4. CLADOPHOROPSIS Borgesen, 1905, p. 288. Frond filamentous, without distinct axis ; basal filaments prostrate, attached by multicellular holdfasts ; erect filaments with more or less abundant branching, with apical growth ; a branch issuing directly under a cross wall, no wall being formed in the branch until the latter has attained a considerable length, and then normally not at the base of the branch ; branches occasionally arising by aplanospore-like bodies formed in the cell, and pushing out through the cell wall ; cells multinucle- ate, with net-shape chromatophore and many pyrenoids ; repro- duction unknown. This genus is practically intermediate between Cladophora and Siphonocladus, showing the close relationship of the Clado- phoraceae and the Valouiaceae. It has the habit of a Clado- phora of the subgenus Aegagropila, but the branches have normally no partition at the base. In this latter respect it agrees with Siphonocladus , but the frond does not originate in a single clavate cell. The secondary branching reminds one of Valonia. We have only one species. C. MEMBRANACEUS (Ag.) Borgesen, 1905, p. 288, figs. 8-13 ; Cladophora membranacea Harvey 1858, p. 73 ; Siphonocladus metn- branaceus Vickers, 1908, p. 20, PI. XVII; P. B.-A., No. 225. Fronds densely matted, up to 10 cm. high, the holdfasts of the prostrate filaments large and well developed ; erect filaments about 1 80 /u, diam., with branches at first alternate, later secund ; partitions formed at irregular but usually long intervals, the terminal cell usually many diam. long ; branches often adher- ing by tenacula similar to the basal holdfasts, but shorter ; branches arising from aplanospore-like formation not uncom- mon. Fig. 129 Fla., W. I. 6. PITHOPHORA Wittrock, 1877, p. 48. Fronds filamentous, monosiphonous, branching, branches is- suing from below the top of the cells ; cells cylindrical or swollen, multinucleate, with net-like chromatophore and many pyrenoids ; asexual reproduction by akinetes, terminal or inter- calary in the filaments, formed by the division of a vegetative cell, the upper half forming the akinete, the lower half remain- THE GREEN ALGAE OF NORTH AMERICA 363 ing usually sterile ; the germinating akinete dividing into two parts, of which one develops a short rhizoid, the other the initial cauloid filament of the future plant. A genus of chiefly tropical and subtropical fresh water plants, closely allied to Cladophora, but the reproduction by akinetes appears to take the place of the reproduction by zoospores and gametes. Sterile plants are practically indistinguishable from Cladophora, but a fertile frond of Pithophora is unmistakable for anything else. Specific distinction, however, is not always easy. The species being naturally tropical, are often found in greenhouses where tropical plants are cultivated. KEY TO THE SPECIES OF PITHOPHORA. i. Intercalary akinetes all of about the same shape. 2. i. Intercalary akinetes varying in the same plant; cylindrical, cask- shaped, obovoid or irregular. 4. 2. Main filament seldom under 150 /* diam. i. P. aequalis. 2. Main filament less than 100 /* diarn. 3. 3. Special helicoidal cells frequent. 3. P. Cleveana. 3. Special helicoidal cells wanting or very rare. 2. P. oedogonia. 4. Main filaments about 165 p diam. 5. P. Roettleri. 4. Main filaments seldom reaching 100 M diam. 4. P. varia. 1. P. AEOUAUS var. FLORIDENS1S Wolle, 1887, p. 131, PI. CXIV, figs. 1-5. Main filaments in fertile plant 150-175^ diam., with a few elongate branches, and many short branches ; cells more or less swollen ; akinetes solitary or rarely two together, intercalary in the main filaments or the long branches, rarely terminal ; intercalary akinetes cask-shaped, with somewhat rounded top, about 215X120,1*,; terminal akinetes cask-shaped, conical or sometimes rounded above, about 270X90 /A. Fla. The type is found in So. America, and has main filaments seldom exceeding 100 /u, diam., and akinetes slightly larger than in the variety. 2. P. OEDOGONIA (Mont.) Wittrock, 1877, p. 55, PI. VI, figs. 1-6 ; including var. vaucherioides Wolle, 1887, p. 130, PL CXIII, figs. 1-7. Main filaments about 70 p. diam., branches of three orders scattered or opposite ; branches occasionally issu- ing from the short cell below the akinete ; akinetes solitary, rarely in twos, intercalary or terminal ; intercalary akinetes cask- shaped, about 230)' 1 15 yu, ; terminal akinetes cask-shaped, above shortly acuminate, with rounded apex, about 215X95^.* Fig. 113. Pa., N. J., Neb. So. America. *P. affinis Nordstedt, 1878, p. 19; Saunders, 1894, p. 66, is reported from Neb., but no specimens have been seen. It was described from 364 TUFTS COLLEGE STUDIES, VOL. II, No. 3 3. P. CLEVEANA Wittrock, 1877, p. 58, PL II, figs. 13-15 ; PL IV, figs. 12-18; PL V, figs. 1-8. Main filaments about 75/0. diam., branches usually of the first order only, occasionally with a few short, scattered or opposite branches of the second order ; special helicoid cells frequent ; akinetes intercalary or terminal, solitary, rarely in twos ; intercalary akinetes cask- shaped, 2oo-26oX 100-160 /j., or subcylindrical, about 165X70 ^ ; terminal akinetes cask-shaped with shortly acuminate rounded apex, 175-240X90-105 /j.. Fla., St. Thomas, Barbados. 4. P. VARIA Wille, P. B.-A., No. 983 ; P. Kewensis Tilden, Amer. Algae, No. 39. Filaments 75-105 /j., primary and sec- ondary branches about the same ; terminal cells 43-70 /*, rarel}r ending in helicoids ; akinetes i-3-seriate, with wall, especially end wall, quite thick, terminal and intercalary, arising in main stem or in branches of any order ; terminal akinetes ovoid, with pointed tip, 150-210X64-69 n- ; intercalary 70-240X60-112 /x ; ovoid, cylindrical or irregular. 111., Mich., Minn. The only species of Pithophora native in colder regions. Nearest related to P. Cleveana Wittr. , but differing in several characters. The akinetes occur even in the shortest branches, some branches consisting of two akinetes and nothing else. The form of the akinetes differs much in the same branch, and series of 2 or 3 are found including every possible combination of cylindrical, ovoid and irregular forms. P. Kewensis Tilden, No. 39, is identical with P. varia ; P. Kewensis Wolle, 1887, p. 131, is founded on sterile plants, and cannot be considered reliable. 5. P. ROETTLERI (Roth) Wittrock, 1877, p. 66, PL I, figs. 12-20; PL V, figs, ii and 12 ; Cladophora Engelmanni Kiitzing, 1849, p. 411. Main filaments about 165 p. diam., branching of three orders ; branches of the first order in whorls of three or more ; of second and third orders scattered or opposite ; akin- etes solitary, rarely in twos, intercalary or terminal ; in the main filaments of irregular and var}dng shape, about 210X190 /A; in the branches cask-shaped, about 260X150^, or cylindri- cal, about 140X80 p.; terminal akinetes obovoid with truncate base, about 210X150 /x, or more rarely subconical with rounded apex, about 250X90^. Cuba, Ark., in warm springs. Asia, Sot. America. Hawaiian specimens, and differs from P. oedogonia by less compound branching, no branches from cells below akiuetes, and akinetes varying much in size, but proportionally stouter than in P. oedogonia. THE GREEN ALGAE OF NORTH AMERICA 365 7. ANADYOMENE L,amouroux, 1816, p. 365. Frond membranaceous, stipitate, membrane consisting of cells of two shapes, the larger, elongate cells forming a branching framework, radiating from the base and palmately divided ; smaller roundish or ovoid cells issuing from the frame- work and filling its intervals, forming a continuous membrane ; in some species the membrane is of two layers of these smaller cells. Zoospores formed in large numbers in the smaller cells, escaping through an opening. Marine. The branching is beautifully symmetrical in the fronds of this genus, showing plainly under a pocket lens, or even to the naked eye. We have two species, one found throughout the warmer Atlantic, the other recorded once only, at some point, not definitely known, in the Gulf of Mexico. KEY TO THE SPECIES OF ANADYOMENE. i. Ribs of a single series of cells, each cell bearing above normally three or more similar cells, palmately arranged. i. A. stellata. i. Ribs composed of several contiguous series of cells, branching only at considerable intervals. 2. A. Menziesii. 1. A. STELLATA (Wulfen) Agardh, 1822, p. 400; Vickers, 1908, p. 21, PI. XXI ; P. B.-A., No. 169 ; A. flabellata Harvey, 1858, p. 49, PL XlylV.A. Fronds often tufted, up to 10 cm. diam., usually ovate or reniform in outline, in older plants often much lobed ; of a single thickness of cells ; the stipe produced into palmately arranged clavate cells, forming similarly dividing series throughout the frond ; interspaces filled with smaller oblong cells, issuing at right angles to the ribs, and forming a continuous membrane. Fig. 125. Fla., W. I. Mediterranean, So. America. J. G. Agardh, 1886, p. 125, mentions two forms ; f. normctlis and f. luxurians, the former with slenderer, longer, clavate or cylindrical rib-cells ; the latter with stouter, shorter, ovoid cells ; but he considers the latter form merely a luxuriant state of the former. 2. A. MENZIESII Harvey, 1858, p. 50; Gravemnia Menziesii J. E. Gray, 1866, p. 51, PI. XLJV, figs, i and 2. Frond up to 25 cm. diam., margin lobed, the stout ribs terminating in the lobes ; rib formed of a bundle of parallel short-jointed filaments, the marginal ones giving out radiating branches of smaller cells, which form the membrane between the ribs. Dredged in 40 meters in the Gulf of Mexico, in 1802, by Archibald Menzies ; not since recorded. 366 TUFTS COLLEGE STUDIES, VOL. II, No. 3 8. MICRODICTYON Decaisne, 1839, p. 115. Frond a sessile, membranaceous net-work, formed of mono- siphonous filaments, densely branching in one plane in a radiate manner, the tip of one branch attaching itself to another branch by a terminal thickening ; irregular, angular open spaces be- tween the cells. Asexual (?) reproduction by zoospores, formed in any cell. Marine. KEY TO THE SPECIES OF MICRODICTYON. i. Cells rarely equalling 200 n diam. i. M. Agardhianuni. i. Cells up to 500 M diam. 2. M. crassum. 1. M. AGARDHIANUM Decaisne, 1839, p. 115; HI. umbilica- tnm Hauck, 1885, p. 467, fig. 203. Frond delicately membra- naceous, filaments 50-200 p. diam., main veins rather distinct, radiate, branches patent; cells usually 2-4 diam. long. Fig. 132. Guadeloupe Island, Cal. Europe. Our plant seems to agree with the common form of the Medi- terranean, which is often known as M. umbilicatnm ; but there is a question whether the European plant is the same as Conferva umbilicata Velley, from the Hawaiian Islands ; Decaisne's specific name is here used as the first one fairly certain. 2. M. CRASSUM J. G. Agardh, 1894, p. 107. Rather coarse in texture, filaments up to 500 /A diam. ; cells seldom longer than broad, somewhat moniliform ; branches of different orders little distinct in size or position. Bahamas. A much coarser plant than our other species. 9. CYSTODICTYON Gray, 1866, p. 72. Frond a perforated membrane with a framework of radiating, monosiphonous, articulate filaments, attached as in Microdictyon ; the intervals being partly filled by smaller cells, with open cen- tral spaces ; reproduction unknown. Marine. In this genus there is the same network of radiate filaments as in Microdictyon ; but there are also many short, one or few celled branches, issuing from the filaments irregularly, and attaching by thickened tips. C. PAVONIUM J. G. Agardh, 1894, p. 109; P. B.-A., No. 666. Frond up to 3 cm. diam. ; main filaments radiating from centers in various parts of the frond, stout, tapering, openings rounded, of various sizes. Fig. 127. Fla. 10. BOODLEA Murray, 1890, p. 243. Frond as in Cladophora, but the branches attaching them- THE GREEN ALGAE OF NORTH AMERICA 367 selves one to another by the thickened tips, forming a more or less spongy frond. From Cladophora, Boodlca is distinguished by the adherent tips of the branches, which, however, do not amount to a dis- tinct organ as in Struvea ; from Microdictyon it is distinguished by branching in all directions. B. COMPOSITA (Harv. and Hook.) Brand, 1904, p. 187, PI. VI, figs. 28-35; Cladophora composita P. B.-A., No. 722. Form- ing spongy, pale green tufts ; filaments soft, pellucid, dichoto- mous below, above with opposite or whorled branches, all at wide angles; cells 2-5 diam. long; 200-225 /"• diam. below, about 1 20 fj. in the ramuli and there not much longer than broad. Fig. 128. British Columbia, Cal. Hawaiian and other Pacific Islands. This specie's occurs in dense masses in the literal zone ; the cells are much swollen, either ovoid or pyriform, the cell wall thin and delicate. The ramuli are usually opposite, but often whorled, and the habit is much like one of the branching Valonias. ii. DICTYOSPHAERIA Decaisne, 1842, p. 32. Frond attached by rhizoids, rounded, solid or hollow, con- sisting of a cellular mass, or of a single layer of closely set, polygonal cells, attached to each other by short tenacula ; frond increasing in size by the division of the cells of the single layer, or by externally giving off dense branches, forming an outer layer, the older layer persistent or perishing ; reproduc- tion unknown. D. FAVULOSA (Ag.) Decaisne, 1842, p. 32 ; Harvey, 1858, p. 50, PI. XUV.B. ; Vickers, 1908, p. 21, PI. XXII; P. B.-A., No. 124. Frond always hollow, hemispherical or oblong in shape, unless broken by external causes; cells 5-6-angled, up to 2 mm. diam. Fig. 137. Fla., W. I., Mexico. Indian and Pacific Oceans. The roundish, light green, berry-like fronds, from 2 to 10 cm. diam., grow attached to corals and rocks, and are not likely to be mistaken for anything else. 12. HORMISCIA Fries, 1835, p. 327. Filaments simple, attached at the base by growths from within the cell, or from the cell wall ; cells multinucleate, all above the base similar, capable of division and of producing zoospores ; chromatophore covering the cell wall, entire or net- 368 TUFTS COLLEGE STUDIES, VOL. II, No. 3 like, with several pyrenoids; asexual reproduction by zoospores, many in a cell, obovoid, extending into a long projection below, and with 4 cilia above ; also by akinetes formed by the break- ing up of the filaments into individual cells, with thick wall, either producing new filaments or zoospores ; sexual reproduc- tion by biciliate gametes. Marine. For discussion of the question of the claims of the generic names Hormiscia and Urospora, see Hazen, 1902, p. 147. KEY TO THE SPECIES OF HORMISCIA. i. Filaments distinctly clavate. 2. i. Filaments nearly cylindrical. 4. 2. Cells, except at extreme base, always wider than long. 4. H. crassa. 2. Cells never shorter than width. 3. 3. Greatest diameter 135 M. 5- H. incrassala. 3. Greatest diameter 500 p.. 2. H. Worinskjoldii. 4. Filaments cylindrical ; fertile cells not swollen. 3. H. Hartzii. 4. Sterile filaments cylindrical or nioniliform ; fertile cells distinctly swollen. 5. 5. Filaments 30-60 fj. diaru., firm. i. H. penicilliformis. 5. Filaments 50-170 fj. diam., very soft and lubricous. 6. H. collabens. 1. H. PENICILLIFORMIS ( Roth) Fries, 1835, p. 327; Con- ferva Yo-imgana Harvey, 1846-51, PI. CCCXXVIII ; Hormotyi- chion spcciositm Harvey, 1858, p. 90 ; Ulothrix isogona Farlow, 1881, p. 45 ; P. B.-A., No. 18. Filaments deep green, attached by outgrowths from within the lower cells, 30-60 p. diam., cells y$-2 diam. long, usually ^-1^2; vegetative cells cylindrical, fertile cells more or less swollen ; chromatophore dense, nearly uniform. Fig. 133. Greenland to N. J. ; Alaska to Cal. Erirope. A common species of northern regions on both sides of the continent, growing on rocks and timber in exposed places, often in company with Bangia fusco-purpurca, and most abundant in spring and summer. 2. H. WORMSKJOLDII (Mert.) Fries, 1835, p. 328; Hor- motrichum (?) Wormskjoldii Harvey, 1858, p. 91 ; Urospora Wonnskjoldii Rosenvinge, 1893, p. 920, fig. 36 ; P. B.-A., No. 915. Filaments attached by fibrils proceeding from the cell wall, 30-60 /A diam. at the base, increasing in size upward, even to 500 /A ; knver cells cylindrical, 3-10 diam. long, upper cells shorter, fertile cells swollen, the largest nearly globular ; chro- matophore an open network. Greenland ; Alaska to Wash. THE GREEN ALGAE OP NORTH AMERICA 369 A northern species, distinguished by the great difference in size between the base and summit of filament ; the lower cells cylindrical, several times longer than broad ; the upper cells ovoid or globular. 3. H. Hartzii (Rosenv.) nov. comb. ; Urospora Hartzii Ros- envinge, 1893, p. 922, fig. 38. Filaments 75-90 /w, thick, of nearly uniform diam., cells ^-3 diam. long, usually 1-2, cylin- drical or very slightly swollen, fertile similar to vegetative ; cell wall thin ; chromatophore an open network. Greenland. This species has only been found unattached ; the manner of attachment, if known, would indicate whether it was allied in this respect with H. pcnicilliformis or with H. Wormskjoldii. 'In the uniform diameter of the filaments it agrees with the former, but has larger and usually longer cells, with thinner walls ; in the arrangement of the chromatophore it agrees with the latter. 4. H. crassa (Rosenv.) nov. comb. ; Urospora crassa Rosen- vinge, 1898, p. 106, fig. 23. Filaments tapering to the base and somewhat to the apex ; lower cells up to 70 p., middle part 120- 150, summit 105 ^ diam. ; cells in smaller portion }-< diam. long, nearly cylindrical; in larger portion y^-l/i diam. long, swollen ; cell wall thick, chromatophore a network with relatively small openings. Greenland. An imperfectly known species, neither the base of the fila- ment nor the fertile cells having been observed ; its best charac- ter would seem to be the short and stout cells. 5. H. incrassata (Kjellm.) nov. comb. ; Urospora incrassata Kjellman, 18973, p. 7, figs. 6-13; P. B.-A., No. 1125. Fila- ments attached by fibrils from the cell wall at the base, about 45 /A diam. at the base, increasing to 135 //., somewhat diminish- ing in the few cells at the apex ; lower cells cylindrical. 1-4 diam. long; upper cells i-il/> diam. long, swollen; cell wall rather thin, chromatophore an open network. Alaska to Cal. Europe. Nearly related to H. Wormskjoldii and H. crassa ; the former has a greater difference in size between base and apex, arid both have thicker cell wall and shorter cells. 6. H. COLLABENS (Ag.) Rabenhorst, 1868, p. 364; Conferva coUabcns Harvey, 1846-51, PI. CCCXXVII ; Ulothrix collabens Farlow, 1881, p. 45 ; P. B.-A., No. 970. Filaments very soft and lubricous, bright green, attached by growths from within the lower cells, cylindrical or increasing slightly upwards, vary- ing much in diameter, 50-170^; cells 1-3 diam. long, usually 370 TUFTS COLLEGE STUDIES, VOL. II, No. 3 somewhat swollen, fertile much swollen ; cell wall rather thin, chromatophore a rather close network. Mass. Europe. The soft, lubricous substance is characteristic of this species, also the great variety in diameter of filaments growing in the same tuft. It is found on exposed rocky shores, in the lower literal region, in very early spring. Family 2. GOMONTIACEAE. Fronds consisting of creeping, branched filaments ; cells multi- nucleate ; asexual reproduction by biciliate zoospores or by aplanospores, both produced in sporangia formed on the upper surface of the horizontal layer, and ultimately detached from the same. Only one genus. GOMONTIA Bornet and Flahault, 1888, p. 163. Characters of the family. KEY TO THE SPECIES OF GOMONTIA. i. In marine shells ; filaments 4-8 ,u diam. i. G.polyrhiza. i. In fresh-water shells ; filaments 12-50 ^ diam. 2. G.Holdenii. i. G. POLYRHIZA (Lagerh.) Bornet and Flahault, 1888, p. 164; 1889, p. Civ VIII, PI. VI, VII; P. B.-A., No. 315. Fila- ments 4-8 fJL diam. ; sporangia 30-40 /j. diam.; zoospores of two sorts, one 10-12X5-6 /A, the other about 5X3.5 ^ ; development not known ; aplanospores 4 n diam. Fig. 135. Abundant everywhere in dead 'shells on the shore ; the fila- ments penetrating the substance of the shell, branching much and irregularly ; sometimes forming a dense network for a con- siderable distance. It seldom occurs quite pure, but is usually in company with Mastigocoleus testcrruni L,agerh. and Hyella cacspitosa B. and Fl. The three species show as stains xon the surface of the shell, each having its own special color; the Gomontia, grass-green ; the Mastigocoleus bluish- or violet-gray ; the Hyella grayish- or yellowish-green. The latter, however, seldom occurs in sufficient quantity or purity to give its own color to the shell. In studying these species the calcareous matter must be dissolved away ; Perenyi's fluid seems to be the best agent. G. polyrhiza probably occurs all along both coasts ; besides inhabiting dead shells, it is found on barnacles, and on the Spirorbis shells attached to Fuci, etc. THE GREEN ALGAE OF NORTH AMERICA 371 2. G. HOLDENII Collins, 1897, P- 95. pl- IV. B., figs. 1-3; P. B.-A., No. 316. Filaments 12-50 /u. diam., cells irregular in shape, oval, cylindrical or polygonal, terminal cell cylindrical or tapering ; sporangia ovoid with elongate base, 100X30^. In Unio shells, in fresh water. Conn. The large irregular cells distinguish this from G. polyrhiza. Family 3. VALONIACEAE. Frond originating in a vesicular or clavate cell of limited x growth, in all but the lowest forms branching or dividing into many cells, which may be irregularly arranged, or may form symmetrical, sometimes netlike fronds. Intercalary cell divi- sion by ordinary wall formation is not common ; new cells arise generally b}^ an outgrowth from the parent in a way that leaves some doubt as to whether the new cell should not be considered as a new individual, or else by the closing in of annular con- strictions of the frond. All marine, chiefly plants of warmer waters. Oltmanns, 1904, p. 255, removes from this family the genera Siphonodadus, Chamacdoris and Struvea, to form the family Siphonocladiaceae. The main distinction seems to be the pres- ence of a distinct axis in the latter. If we follow Borgesen, 1905, p. 288, and remove from Siphonodadus S. membranaceus and its allies, this genus and the remaining genera of the family agree in the presence of an original upright cell of limited growth, and in the absence or rarity of intercalary division of the cells by cross walls ; there would seem to be no need of dividing the family. KEY TO THE GENERA OF VALONIACEAE. i. Frond always unicellular. i. HAUCYSTIS. i. Mature frond pluricellular. 2. 2. Original cell constituting a stipe different in character from the rest of the frond. 3. 2. All cells similar to the original. 4. 3. Stipe crowned by a network. 6. STRUVEA. 3. Stipe crowned by a dense tuft of filaments. 5. CHAMAEDORIS. 4. Daughter cells arising from the surface of the mother cells. 2. VALONIA. 4. Entire contents of cell dividing into numerous smaller cells, each of which may develop like the mother cell. 5. 5. Erect or tufted, not calcined. 3. SIPHONOCLADUS. 5. Forming an adherent disk ; somewhat calcified. 4. PETROSIPHON. 372 TUFTS COLLEGE STUDIES, VOL. II, No. 3 i. HALICYSTIS Areschoug, 1850, p. 447. Frond unicellular, multinucleate, saccate, with narrow basal portion; chromatophores minute disks without pyrenoid. Asexual reproduction by biciliate zoospores without stigma, es- caping through one or more openings ; similar but smaller zoogarnetes (?) formed in separate individuals ; after the emis- sion of the spores the openings close and several new genera- tions of spores can be similarly produced. Though this genus was proposed for the following species as long ago as 1850, its validity has been questioned, but studies by Kuckuck, 1907, remove all doubt. H. OVALIS (L/yng.) Areschoug, 1850, p. 447 ; Kuckuck, 1907, p. 139, PI. III. Fronds solitary or gregarious, obovate-ovoid, y^-i cm. high, about half as wide ; membrane tough, 10-12 /u. thick ; basal prolongation penetrating the substratum ; zoo- spores 12-14X7-8 /u. ; gametes (?) 7-8X2-3 /x. Fig. 130. Van- couver Island to Monterey, Cal. Northern Europe. This species has always been found growing on crusts of Lithothamnion or similar calcareous algae, the radical portion boring deeply into the substratum, apparently like Gomontia. 2. VALONIA Ginnani, 1757, p. 38. Fronds not calcified, at first a single ovoid or clavate multi- nucleate cell, producing more or less numerous cells similar in form to itself ; this process being repeated more or less fre- quently in different species; unicellular rhizoids being similarly produced ; chromatophore forming a network with many pyre- noids ; asexual reproduction by 2- or 4-ciliate zoospores, escap- ing through numerous openings, and developing at once into plants similar to the parent. As long as V. ovalis was included in this genus, it was diffi- cult to define the latter clearly ; by the removal of that species as Halicystis ova/is, the matter is much simplified. KEY TO THE SPECIES OF i. Frond bullate, unbrauched. i. V. I'entricosa. i. Frond more or less abundantly branched. 2. 2. Cells obovate-clavate, sparingly and irregularly branched. 2. V. utricnlaris. 2. Cells subcyliudrical. 3. 3. Branches irregularly placed. 3. V. aegagropila. 3. Branches in regular whorls. 4. 4. Whorls frequent and dense; cells rather short. 4. V. verticillata. 4. Whorls distant and loose, cells long. 5. V. confervoides. THE GREEN ALGAE OF NORTH AMERICA 373 1. V. VENTRICOSA J. G. Agardh, '1886, p. 96; Murray, 1893, PI. XIII, figs. 6-10 ; Vickers 1908, p. 21, PI. XXIII. A. Frond solitary, saccate, spherical to pyriform, usually 2-3, rarely 5 cm. diam. ; secondary cells formed chiefly at the base for pur- poses of attachment ; membrane smooth, translucent, showing the light green contents. W. I. Practically unmistakable for any other species ; Halicystis ova/is, the only one that it resembles, being smaller and an in- habitant of quite different regions. The fronds are usually about the size of a large cherry, but Murray has dredged specimens " as large as a hen's egg." 2. V. UTRICULARIS Agardh, 1822, p. 431 ; Kiitzing, 1856, PI. LXXXVI, .fig. 2b-e; Wittr. and Nordst., Alg. Exsicc., No. 953. Cells stout, cylindric-clavate, with similar prolifera- tions ; lower parts of frond decumbent, or creeping among other algae, then erect, up to 5 cm. high, often forming dense tufts ; membrane dark green, shining ; zoospores biciliate. Fig. 138. Bermuda, Bahama. Europe. Growing from the litoral zone to a depth of 2 m.; in the former station the filaments are shorter and stouter ; in the lat- ter longer and more slender. 3. V. AEGAGROPILA Agardh, 1822, p. 429; Kiitzing, 1856, PI. IvXXXVII, fig. i ; P. B.-A., No. 772. Fronds much and irregularly branched, cells subcylindrical, rather short, 2-3 mm. diain., forming a dense, globular tuft; membrane rather dull. W. I. Mediterranean, Indian, Pacific Oceans. Nearly allied to V. utricnlaris, but with more slender, less clavate cells, and forming denser masses, soon freed from the substratum and floating in shallow water. 4. V. VERTiCiivivATA Kiitzing, 1849, p. 508 ; 1856, p. 30. PI. LXXXVIII; Vickers, 1908, p. 21, PI. XXIII. B ; P. B.-A., No. 1533. Cells .cylindrical, straight, 2-3 mm. diam., -producing whorls of similar cells below the obtuse apex ; branching re- peated, forming tufts about 5 cm. high ; membrane very deli- cate and translucent. W. I. The regular and frequent whorled branches distinguish this from all our other species ; dried specimens adhere to paper more firmly than in other species. 5. V. CONFERVOIDES Harvey, Alg. Ceylon Exsicc., No. 73 ; Wittr. and Nordst., Alg. Exsicc., No. 349. Fronds decum- bent at first, then ascending, cylindrical, 2-3 mm. cliam., simple below, above branching sparingly, usually 3-4 branches in a 374 TUFTS COLLEGE STUDIES, VOL. II, No. 3 whorl, branches patent, more or less incurved, membrane firm, color dull green, forming dense tufts, many cm. diam. Ber- muda. Indian and Pacific Oceans. Like V. •vcrticillata this species has whorled branches, but the whorls are fewer branched and less frequent ; the cells are many times longer. 3. SIPHONOCLADUS Schmitz, 1878, p. 17. Frond originating in a simple clavate cell, attached by multi- cellular rhizoids at the base, of definite growth ; ultimately be- coming multicellular by the transformation of the contents into cyst-like cells, uniting sub-parenchymatously, then each push- ing through the mother cell wall, assuming a shape like the mother cell and developing in the same way as the latter. Asexual reproduction by escape and growth of the cysts ; re- production also by zoospores formed in large numbers in the clavate cells; probably asexual. Ordinary cell division by cross walls not certainly observed. The primary cell in Valonia appears to bear branches with a partition at the base of each ; in Siphonocladus a multicellular filament appears to take the place of the primary cell, each cell of the filament producing a branch without partition at the base. KEY TO THE SPECIES OF SIPHONOCLADUS. i. Primary cell long, erect ; substance soft. i. S. tropicus. i. Primary cell short ; substance firm and crisp. 2. .5". rigidus. 1. S. TROPICUS (Crouan) J. G. Agardh, 1886, p. 105; Howe, 1905, p. 245, PI. XIII, fig. 2 ; Vickers, 1908, p. 20, PI. XVIII. Primary cell up to 4 cm. long, i cm. wide, with annular constrictions near the base ; branches similar, also with constrictions near base, often longer than the primary cell ; cells of third generation similar but generally shorter ; zoospores many in a cell which has reached its full growth, escaping by small perforations in the walls. Fla., W. I. 2. S. RIGIDUS Howe, 1905, p. 244, PI. XII, fig. i ; PI. XIV ; P. B.-A., No. 1489; 5. tropitus P. B.-A., No. 1031. Frond a more or less dense tuft of pale green, crisp filaments, main axis hardly distinguishable ; branching sub-dichotomous, irregular, or secund ; filaments 350-1100 ^ diam., often united by short tenacula. Fig. 139. Bahama. Howe's description of this species was apparently written without knowledge of Borgesen, 1905, which was published about the same time ; in the light of Borgesen's studies of .5". THE GREEN ALGAE OF NORTH AMERICA 375 tropicus, Howe's figures of S. rigidus would seem to be inter- preted best as representing a development by "cysts," much as in the former species. There is little doubt of the distinct- ness from S. tropicus, but the relations in this direction are cer- tainly closer than those with Cladophoropsis membranaceus . It is at least probable that the lateral branches in Howe, PI. XIV, fig. 2, correspond to the branches in Borgesen, fig. 4 ; and that the frond originates in a similar, somewhat clavate cell. 4. PETROSIPHON Howe, 1905, p. 248. Filaments united to form a disk, somewhat calcified, firmly attached to the substratum, and piercing the same by rhizoids ; disk monostromatic at the margin, polystromatic elsewhere, the center often of short, erect filaments ; asexual reproduction by aplanospores. P. ADHAERENS Howe, 1905, p. 248, PI. XV. Disks light green, 2-6 cm. diam., orbicular or irregular, closely approxi- mate ; margin striate ; up to 5111111. thick at the center; hori- zontal filaments 300-850 /j. diam., straight or geniculate, dichoto- mous ; cells ^2-20 diam. long ; rhizoids very abundant, pene- trating the substratum ; aplanospores varying in size and form. Bahamas. In characters of filaments, etc., like Siphonoclctdus, but differ- ing by the definite disk-shaped frond, and the incrustation ; it is closely adherent to the rock on which it grows. 5. CHAMAEDORIS Montague, 1842, p. 261 Frond erect, with firm, clavate stipe, attached by rhizoids at the base, and bearing a dense tuft of branching, articulate fila- ments at the tip ; stipe monosiphonous, with closely set, annular constrictions, much calcified. C. ANNUI,ATA (Lamarck) Montagne, 1842, p. 261 : Harvey, 1858, p. 43, PI. XIvII.B ; Vickers, 1908, p. 22, PI. XXIV ; P. B.-A., No. 629. The only species ; stipe up to 10 cm. high; head 2-3 cm. diam. Fig. 136. Fla., W. I. Africa, So. America, Indian Ocean. . The mop-shaped fronds are not to be mistaken. 6. STRUVEA Sender, 1845, p. 49. Frond attached below by multicellular branched rhizoids ; stipe simple or branched, monosiphonous, bearing one or more flabelliform, net-like expansions, consisting of articulate, pin- natel}7 branched filaments, the tips of the branches attaching 376 TUFTS COLLEGE STUDIES, VOL. II, No. 3 themselves to other filaments to form the network. Reproduc- tion unknown. A genus of tropical algae, with beautifully symmetrical net- like fronds, in which the filaments apparently anastomose, but really are united by peculiar organs, "tenacula," formed on the tips of the cells when they come in contact with other cells of the fronds, or, in some species, of other fronds. The tenacula are short cylindrical prolongations of the cell wall, ending in dense short branches ; reminding one somewhat of the shape of a sea-anemone. In the corresponding organs in Microdidyon the attaching surface has a somewhat crenulate margin, but does not develop branches. The primary cell of Struvea is at first clavate, later spindle-shaped, and appears to attain its full growth before the network is formed. There is some uncer- tainty as to how the " articulations " of the network arise, but it seems probable that it is by the deepening of the annular con- strictions, not by true wall formation. KEY TO THE SPECIES OF STRUVEA. i. Stipe uubranched. i. 5". anastomosans. i. Stipe branched. 2. 2. Each branch of the stipe with a separate network. 3. 5". ramosa. 2. Oue network only. 2. 6". pulcherrima. i. S. ANASTOMOSANS (Harv.) Piccone, 1884, p. 20; S. deli- catida Murray and Boodle, 1888, p. 281, PI. XVI, figs. 6 and 8 ; Vickers, 1908, p. 20, PI. XIX ; Cladophora anastomosans Harvey, 1855, p. 565, name only; 1859, PI. CI. Stipe smooth, simple, slender, crowned with a subpyramidal network, 3-5 cm. long ; filaments repeatedly pinnate, pinnae and pinnules opposite, horizontally patent, more or less attached to each other. Fig. 134. Guadeloupe, Jamaica. Australia, Canaries. This species shows a resemblance to the Pcllucida section of Cladophora ; the union of the branches is only partial, and varies much as to completeness. Var. CARACASANA Grunow in Murray and Boodle, 1888, p. 281 ; Vickers, 1908, p. 20, PI. XX. Frond regularly bipinnate ; branches seldom united. Barbados. So. America. 2. S. PULCHERRIMA (J. E. Gray) Murray and Boodle, 1888, p. 281, PI. XVI, fig. 4. Stipe smooth, three-parted, crowned with a single, cordate, three- ribbed network, 30X20 cm. ; fila- THE GREEN ALGAE OF NORTH AMERICA 377 merits repeatedly pinnate, articulations of the pinnae 3-4 diatn. long, of the pinnules 2 diatn. Fla., Gulf of Mexico. This species was dredged by Menzies early in the last cent- ury, and his single specimen remained undescribed until 1866, when it was taken by J. E. Gray, 1866, p. 70, as the type of the new genus Phyllodictyon. The original specimen, though over 30 cm. long, is evidently fragmentary ; a single, smaller frag- ment, found by Mrs. G. A. Hall, at Jupiter Inlet, Florida, is the only record since Menzies. 6". pulcherriina seems to be the rarest, as well as one of the most interesting of our green algae. 3. S. RAMOSA Dickie, 1874, p.. 316; Murray and Boodle, 1888, p. 280, PI. XVI, fig. 3. Stipe with a few annular con- strictions, above oppositely branched, each branch ending in a sub-elliptical network, about 3X1^2 cm.; filaments tripinnate, lower articulations 7-8 times their diam., upper 3-4 times. Bermuda. Family 4. DASYCLADACEAE. Frond consisting of a long, inarticulate axillary cell, attached by rhizoids below, and of whorls of usually pluricellular, simple or branching ramuli of limited growth ; in fertile ramuli are produced either gametes, or aplanospores which when freed produce gametes. Marine plants of warm waters and general distribution. KEY TO THE GENERA OF DASYCLADACEAE. i. Frond calcified. 2. i. Frond not calcified. 6. 2. Frond with slender stipe and with whorls of branches terminal or at considerable intervals. 3. 2. Whorls of branches contiguous, concealing the axis. 5. 3. Spores contained in whorled branches, not calcified. I. ACETABULARIA. 3. Spores contained in whorled branches, calcified. 4- 4. Spores imbedded in a solid mass of lime, but membrane free from lime. 3. ACICULARIA. 4. Spores free, membrane much incrusted. 2. CHALMASIA. 5. Stem branching, moniliform. 5. CYMOPOLIA. 5. Stem unbranched, surface continuous. 4. NEOMERIS. 6. Sporangia terminal ; whorls very closely set. 6. DASYCLADUS. 6. Sporangia lateral, whorls rather distant. 7. BATOPHORA. i. ACETABULARIA L,amouroux, 1816, p. 244. Frond calcified, with perennial root and annual erect axis 378 TUFTS COLLEGE STUDIES, VOL. II, No. 3 clothed with deciduous whorls of hairs, terminating in a cap- like whorl, with rays either free or joined; each ray bearing on its upper surface near the base a prominence, the prominences forming a ring " corona superior," with scars corresponding to deciduous tufts of hairs borne by them. A corresponding ring on the lower surface of the rays " corona inferior " is present in some species. Entire contents of the rays changing into glo- bose or ovoid aplanospores with membrane free from lime ; after a period of rest these aplanospores open by a cap, and give out zoogametes, which by conjugation form a zygote, by whose germination the plant is reproduced. A genus of very delicate and beautiful plants, seldom over a few cm. high, living in shallow salt water in tropical and sub- tropical regions. The two following genera, Chahnasia and Acicularia, are practically of the same habit, but differ in spore characters. KEY TO THE SPECIES OF ACETABULARIA. i. Rays less than 20. 2. i. Rays 20 or more. 3. 2. Corona superior not over 35 /u diam. 5. A. pttsilla. 2. Corona superior 75 ^ diam. or more. 4. A. polyphysoides. 3. Rays apiculate. i. A. crenulata. 3. Rays not apiculate. 4. 4. Rays free or slightly coherent. 3. A. Farlowii. 4. Rays firmly united. 2. A. caliculus. 1. A. CRENULATA L/amouroux, 1816, p. 249; Harvey, 1858, p. 40, PI. XLII.A. ; Vickers, 1908, p. 29, PI. XL,VIII ; P. B.-A., No. 125; A. caraibica Kiitzing, 1856, p. 33, PI. XCIII ; Vickers, 1908, p. 29, PL XLJX. Stipe up to 4 cm. high, bearing a terminal disk with crenulate margin, 6-15 mm. diam., and often several other disks at various points, or nodes showing the positions of former disks ; rays (sporangia) 30-80, firmly united, ends arched, with a short apiculum at the middle ; corona superior .15-. 26 mm. diam., with two hair-scars on each ray; aplanospores 75-140 /* diam., 300-500 in a sporangium. Fig. 131. Fla., W. I. A common and beautiful species, in general shape like a small and delicate mushroom. A. caraibica is kept distinct by Solms, 1895, but Howe, 1901, having made a careful study of the living plants of our American species, finds it impossible to distinguish the two. 2. A. CALICULUS Ouoy and Gaimard, 1824, p. 621, PL XC, figs. 6 and 7; Solms, 1895, p. 25; A. Snhrii Solms, 1895, p. THE GREEN ALGAE OF NORTH AMERICA 379 25, PI. I, figs. 9 and 13. Slender, stipe 1^-3 cm. high, with occasional spindle-shaped swellings; disk cup-shaped, 6-7 //, diani. ; rays 25-30, not strongly united, the blunt margin with a broad, deep, squarish depression ; corona superior about 90 //, diani., with 2 or 3, sometimes 4 hair-scars on each ray ; aplano- spores about 160 ^ diam., about So in a sporangium; gametes developed before the release of the aplanospores from the sporangium. St. Thomas, Jamaica. Indian and South Pacific Oceans. In general appearance like a delicate A. cremdata, but with only one disk, different shape in the margin of the disk, usually more hair-scars than in A. crenulata, and with rays less firmly united. 3. A. FARLOWII Solms, 1895, p. 27, PI. Ill, fig. i ; P. B.-A., No. 1032; Acetabulum Farlowii Howe, 19053^.577. Stipe 1-2 cm. high; disk 4-7 mm. diam., nearly flat; rays 20-30, lightly coherent or free, slightly compressed towards the obtuse or truncate ends ; corona superior .15 mm. diam., with two hair- scars on each ray ; aplanospores 40-120 in a sporangium. Fla. Distinguished from A. crcnulata by the loosely attached or entirely free rays, and from A. caliculus by the flattish disk with obtuse rays; in mature plants the rays- are often entangled, so that the regular form of the disk is lost. 4. A. POLYPHYSOIDES Crouan in Schrarnm and Maze, 1866, p. 101 ; Solms, 1895, p. 29, PI. IV, figs. 2 and 6 ; Vickers, 1908, p. 28, PI. XLVII ; Acetabuhim polyphysoides Howe, 1909, p. 92, PI. VI, figs. 16-20; PI.- VII, figs. 5-9. Stipe seldom over i cm. high, disk single, cup-shaped or nearly flat, 2-5 mm. diam. ; rays 11-25, mostly 12-18, vesicular, from obovoid to sub- fusiform, obtuse and rounded at the end, loosely united by a thin calcification; corona superior 75-150 //. diam., a whorl of 5-13, usually 8 or 9, hair-scars on each ray; aplanospores 90- 190 /A diam., 6-50 in a sporangium. W. I. The few and swollen rays sufficiently distinguish this species from the preceding, apart from the characters of the hair-scars. Forma deltoidea (Howe) nov. comb.; Acetabulum polyphys- oides ddtoideum Howe, 1909, p. 92, PL VI, fig. 21 ; PI. VII, fig. 10. Rays usually 7, much inflated, inversely deltoid or obovoid-deltoid ; hairs scars 6-8. Bahamas. Very distinct in appearance by the few and broad rays, but there are intermediate forms between this and the typical form. 5. A. pusilla (Howe) nov. comb.; Acetabulum pusillum 380 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Howe, 1909, p. 89, PI. VI, figs. 13-15: PL VII, figs. 1-4. Stipe 1-3 mm. high, disk solitary, nearly flat, 1-2.5 mm- diam., rays 6-17, usually 11-15, obovoid-clavate to clavate-subfusiform, blunt or obtusely taper-pointed, easily separable ; corona supe- rior 22-35 /"• diam., with 2, rarely 3 hair-scars ; aplanospores 15-60 in a sporangium, 68-82 /A diam. W. I. The smallest of our species, and quite lightly calcified. 2. CHALMASIA Solms, 1895, p. 32. Disk terminal, composed of rays united only by the incrusta- tion ; corona inferior wanting ; segments of the corona superior not touching laterally ; aplanospores free, with thick, much cal- cified membrane. Only one species. C. ANTILLANA Solms, 1895, p. 32, PL III, figs. 2, 3, 5. Disk funnel-shaped, 6 mm. diam., rays 25-32, covered with a thin, easily detachable incrustation, and not otherwise united, vesic- ular and inflated ; aplanospores globular, chalk-white ; hair- scars 2-3. Fig. 140. In habit quite like a small Acetabularia crcnnlata, but suffi- ciently distinct in the spore characters. The only known speci- mens were dredged at some point, not definitely known, off the Florida coast. 3. ACICULARIA D'Archiac, 1843, p. 386. Rays of the disk united, corona superior and corona inferior present ; interior of the ray ultimately occupied by a calcareous mass enclosing uncalcified aplanospores. The genus was founded by the paleontologist D'Archiac in 1843, on certain minute spicules found in the Eocene formation in France ; two or three other fossil species have since been recognized, but only one living species is known. A. SCHENCKII (Mob.) Solms, 1895, p. 33, PL III, figs. 4, 9, n, 12, 14, 15. Stipe 1-3 cm. high, thin-walled, rather stout; disk 6 mm. diam., flat or nearly so, with crenulate margin; rays 30-50, fairly closely united, wedge-shaped ; corona superior 13 mm. diam., with 2 hair-scars to each ray; aplanospores 100-200 in a ray, globose, 60-80 /x diam. From literal to 30 m. depth. Bermuda, Martinique, Guadeloupe. So. America. 4. NEOMERIS L-amouroux, 1816, p. 241. Frond cylindric-clavate, more or less strongly calcified, con- sisting of a simple, inarticulate axis, attached by lobed or branched holdfasts, and bearing thickly set, uniform whorls of 12-80 primary branches, each branch except those of the lower whorls bearing a terminal short-stiped sporangium, and two THE GREEN ALGAE OF NORTH AMERICA 381 secondary branches, whose swollen tips constitute the surface of the frond, and which when young bear each a simple or branch- ing hair ; sporangium containing a single large spore, probably an aplanospore, with an operculum at the base; development unknown. Rather insignificant appearing plants, the species much alike in habit, demanding dissection and microscopic examination for specific determination. Howe, 1909, gives full details of foreign as well as of American species. KEY TO THE SFECIES OF NEOMERIS. i. Branches of the second order subfusiform, hardly forming a cortex. 4. N. Cokeri. i. Ends of the branches of the second order forming a cortex with dis- tinct facets. 2. 2. Sporangia laterally coherent by the calcareous coating. 3. N. annulata. 2. Sporangia strongly calcified but mutually free. 3. 3. Plants 1-2 mm. thick, 15-20 times as long. i. N. diiDiefosa. 3. Plants 1.5-2.5 mm. thick, 4-8 times as long. 2. N. mucosa. 1. N. DUMETOSA L,amouroux, 1816, p. 243, PI. VII, fig. 8; Howe, 1909, p. 77, PL I, fig. i ; PI. V, fig. 20; PI. VI, figs, i and 2. Gregarious or scattered, subcylindrical, slender, 20-40 mm. high, 1-2 mm. thick, apex acute or acuminate ; primary branches 500-700 //, long, 14-30 /j. diam., 28-40 in a whorl, whorls 300-400, averaging 100 p. apart, more distant near the apex ; secondary branches capitate, inflated at the tip to 100-185 p. diam., outwardly rounded, strongly calcified except on the outer surface ; sporangia strongly calcified but mutuall)7 free, containing each an aplanospore 135-160X130-155 p.. W. I. Europe. The original species of the genus, and the one to which all forms were first referred ; not found in recent years in the West Indies, very likely narrowly limited in its localities, like some of the other species of the genus. 2. N. MUCOSA Howe, 1909, p. 84, PI. I, fig. 5 ; PI. V, figs. 1-14. Gregarious, mostly in clusters of 3-20; subcylindrical or fusiform, 8-20 mm. high, 1.5-2.5 mm. thick, apex acute or acuminate ; primary branches 275-400 ^ long, cylindrical or clavate, mostly 40-100 ^ diam., 28-48 in a whorl, whorls 120-300, averaging 120 /u, apart ; secondary branches capitate, inflated at the tip to 100-220 /u, diam., strongly calcified except at the end surface, which is mammiform, subconical or subrostrate, with very^thin, mucilaginous wall ; sporangia strongly calcified but 382 TUFTS COLLEGE STUDIES, VOL. II, No. 3 mutually free ; aplanospores obovoid, 140-160X105-120 p.. Ba- hamas, Cuba. A shorter and stouter plant than N. dumetosa, with very soft and gelatinous membranes. 3. N. ANNULATA Dickie, 1874, p. 198 ; Howe, 1909, p. 87, PL I, fig. 2; N. Kelleri Cramer, 1888, p. 3, PI. I, fig. 2 ; PI. II, figs. 1-12; PI. Ill, figs. 1-2; 1890, p. 9, PL I, figs. 1-12; PL II, figs. 1-6; PL IV, figs. 15-24; Vickers, 1908, p. 28, PL XL/ VI ; N. dumetosa P. B.-A., No. 668. Mostly densely gre- garious, subcylindrical or fusiform-clavate, 5-25 mm. high, 1-2 mm. thick, apex subacute ; primary branches 200-280 /u, long, 11-20 /j. median diam., 20-56 in a whorl, whorls 60-175, 115-250 p. apart ; secondary branches capitate, inflated at the tip to 80-135 /"• diam., outwardly usually rounded, rather firm-walled, strongly calcified except at the outer end, firmly coherent ; sporangia strongly calcified and laterally coherent into nearly complete or more or less interrupted rings ; aplanospores oblong-ovoid to oblong-ellipsoid, 115-175X46-80 p.. Fig. 143. Fla., W. I. So. America, Indian and Pacific Oceans. The complete or somewhat broken rings of sporangia can gen- erally be depended on to distinguish this species. 4. N. COKERI Howe, 1904, p. 97, PL VI, figs. 3-12; 1905, p. 580; 1909, p. 89, PL I, fig. 6. Solitary or somewhat grega- rious, subcylindrical or clavate, 7-37 mm. high, 1.5-3 mm. diam., apex rounded, obtuse or subtruncate ; primary branches 200-300 p. long, 30-40 /j. diam., 12-56 in a whorl, whorls 60-175, about 100 fi apart; secondary branches somewhat calcified, scarcely adherent, subfusiform, curved or gibbous, 100-150 /u. diam. near the middle, tapering to 22-34 p. at the truncate apex; terminat- ing in a hair ; hairs of two kinds, the first unicellular, clavate, curved or hooked, diam. about equal to that of the supporting cell, the second with a similar but narrower basal cell, bearing at its apex two slender, subcylindrical cells, each in its turn with 2-4 similar but smaller branches ; the two forms of hairs in separate zones ; sporangia strongly calcified, free or coherent in rows of 2-8 ; aplanospores obovoid or oblong-ellipsoid, 140- 190 >< 82-94 /*• Bahamas. Distinguished by the fusiform secondary branches and the two types of hairs, in distinct zones on the same individual. 5. CYMOPOLIA L,amouroux, 1816, p. 292. Frond branched, consisting of a series of bead-like calcified joints, connected by contracted, flexible uncalcified portions, in which the branching occurs ; stem and branches terminated by THE GREEN ALGAE OF NORTH AMERICA 383 tufts of branched, pluricellular hairs ; at the uncalcified por- tions, whorls of sterile, undivided branches ; in the calcified portions, \vhorls of branches each with a terminal sporangium, and branches enclosing and passing beyond it ; the swollen ends forming the surface of the frond. Development of spores unknown. C. BARBATA Lainouroux, 1816, p. 293; Harvey, 1858, p. 36, PI. XLI.A. ; P. B.-A., No. 28. Frond to 20 cm. long, varying much in density of branching ; joints from depressed-spherical to cylindrical and several diameters long; visually 1-3 mm. diam. ; 10-30 whorls of branches in a joint, 20-30 branches in a whorl ; sporangia globose or short-pyriform, 160-200 i^ diam. Fig. 146. Fla., W. I. C.' rosarium L,amouroux and C. mcxicana J. G. Agardh repre- sent extreme forms, the former with joints mostly globular, the latter with joints mostly cylindrical. A single plant will often have branches representing these extremes, which therefore should not have even varietal rank. 6. DASYCLADUS Agardh, 1827, p. 640. Stem unbranched, cylindric-clavate, uncalcified, attached at the base by a lobed expansion,, and bearing in the upper'part whorls of about 12 ramuli each; ramuli repeatedly branching, each branch a distinct cell ; gametangia spherical, terminal on the first cell of a ramulus and surrounded by its branches, producing biciliate gametes, by whose union is formed a zygote, germinating immediately. D. CLAVAEFORMIS (Roth ) Agardh, 1828, p. 16 ; Kvitzing, 1856, PI. XCI, fig. 2 ; P. B.-A., No. 170. Fronds gregarious, 2-4 cm. high, abovit 5 mm. diam. ; whorls of ramuli closely set ; gametangia 400-550 /A diam. Fig. 142. Fla., W. I. Mediterranean . With the exception of a short basal portion, the whole of the axis is covered with whorls so closely set as to form an appar- ently solid mass, the individual whorls being quite indistin- guishable. In drying the plant usually gives ovit a brownish- yellow fluid, staining the paper on which it is mounted. 7. BATOPHORA J. G. Agardh, 1854, p. 108. Vegetative frond as in Dasycladits ; sporangia chiefly lateral on the ramuli and their branches, producing aplanospores. B. OERSTEDI J. G. Agardh, 1854, p. 108 ; P. B.-A., No. 1490; Bolryophora Conqucrantii Cramer, 1890, p. 6, PI. IV, fig. i ; B. occidentalis P. B.-A., No. 667 ; Coccodadus occidcntalis var. 384 TUFTS COLLEGE STUDIES, VOL. II, No. 3 laxus Howe, 1904, p. 95, PI. VI, figs, i and 2. Fronds up to 10 cm. high, rather soft and flaccid, 10-13 mm. diam. ; whorls distinct, not very close ; sporangia ellipsoid to pyriform-sub- clavate, 500-1000X325-450 /A, lateral or occasionally terminal on branches of the first to the fourth orders ; aplanospores ellipsoid, 50-70 /A diam., i*/, times as long, in a single layer on the inner surface of the sporangium. Fig. 145. Fla., W. I. Var. OCCIDENTALS (Harv.) Howe 19053, p. 579; Dasydadns occidcntalis Harvey, 1858, p. 38, PI. XLJ.B. Fronds shorter and smaller, whorls more closely set, ramuli less branched ; sporangia spherical or nearly so ; aplanospores more numerous, nearly filling the sporangium. With the type. The form described as B. Ocrstedi is a plant of quiet brackish waters ; the var. occidcntalis inhabits exposed shores, and quite resembles Dasydadus ; like the latter, the plants stain paper yellow, while plants of the type do not. Family 5. SPHAEROPLEACEAE. Frond an unattached, riionosiphonous, unbranched filament, consisting of long, cylindrical, multinucleate cells, each with many minute, disk-shaped chromatophores arranged in distinct zones, and many pyrenoids ; sexual reproduction by antheridia and oogonia, which may be formed in the same or in separate filaments ; antheridia formed of vegetative cells, unchanged in shape and size, the contents becoming orange colored, and transformed into a large number of long-clavate or spindle- shaped, biciliate spermatozoids, escaping through numerous openings in the cell wall ; oogonium from a vegetative cell, un- changed in shape or size, the contents transformed into numer- ous spherical, uninucleate oospores, fertilized by sperm atozoids entering the cell by numerous openings ; oospore after fertiliza- tion brick-red, with three colorless membranes, the outer mem- brane ample and with wavy folds ; germinating oospore produc- ing 1-8 biciliate zoospores, which on germination are much elongated, and ultimately form a filament like the normal, but with pointed ends ; unfertilized oospores may sometimes ger- minate parthenogenetically. A rather isolated family, represented by only one genus. SPHAEROPLEA Agardh, 1824, p. XXV. Characters of the family. vS. ANNULINA (Roth) Agardh, 1824, p. 76; Wolle, 1887, p. 104, PI. CXXIII, figs. 1-5; P. B.-A., No. 317. Filaments 27- 72 /j. diam., cells 8-20 diam. long ; 20-30 zones of chromatophores THE GREEN ALGAE OF NORTH AMERICA 385 in a cell; oospores usually in two longitudinal series, 11-26 /j. diam., including membrane. Fresh water. Fig. 141. Minn., Cal. Europe. A plant of shallow, easily dried pools ; the oospores retaining vitality for years, and germinating when again moistened. Of wide distribution in isolated stations. Klebahn, 1899, divides .S. annulina into two species, 6". crassi septa (Heinrich) Klebahn, and 6". Braunii Kiitzing ; the former with filaments 27-35 V- diam., 500-1200 p. long, oospores 11-19 /a diam., including mem- brane, mostly 14 //., dissepiments thick, often with conical pro- jections ; the latter with cells 42-65X250-1400 /x, oospores 13-26 p., mostly 17-19 /A, dissepiments relatively thin and even. Whether there are two distinct species, or only two forms or varieties of 5". annulina, is hardly certain ; in the former case it would not seem that the name of ,S\ annulina should be given up in favor of S. crassisepta ; all American specimens examined are of the crassisepta type. Order VI. SIPHONALES. Fronds filiform, usually much branched or developing into various forms, continuous without dissepiments in the vegeta- tive condition, multinucleate, with many lens- or disk-shaped chromatophores. KEY TO THE FAMILIES OF SIPHONALES. i. Sexual reproduction by motile gametes or unknown. 2. i. Sexual reproduction by non-motile oospores and motile sperrnato- zoids. 6. VAUCHERIACEAE. 2. Frond differentiated into root, stem and branches, the latter of very varied form; reproduction unknown. 5. CAULERPACEAE. 2. Frond filiform, branching ; not differentiated as above. 3. 3. Filaments interwoven to form fronds of definite form. i. CODIACEAK. 3. Filaments branching, not interwoven. 4. 4. Sexual reproduction by large female and small male gametes; asexual reproduction unknown ; branching more or less plumose. 2. BRYOPSIDACKAK. 4. Sexual reproduction unknown ; branching irregular. 5. 5. In tissues or shells of plants or animals ; asexual reproduction by aplanospores. 4. PHYLI.OSIPHOXACEAE. 5. Free, marine ; asexual reproduction by large, uiulticilate zoospores. 3. DEKI'.KSIACEAE. 386 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Family i. CODIACEAE. Frond except in the lowest forms of definite shape, composed of interwoven, continuous, branching filaments, sometimes ap- parently pluricellular by constrictions, calcified or not.. Asex- ual reproduction by zoospores and aplanospores, formed in spo- rangia ; sexual reproduction by zoogametes, the sexes either similar or differing in size. KEY TO THE GENERA OF CODIACE'AE. i. Not calcified nor stipitate, soft and spongy ; cortical layer formed of the s\vollen ends of the longitudinal filaments. Subfamily COD- IOIDEAE. i. CODIUM. i. Stipitate or of seriate disks, often calcified ; cortical layer, when present, formed of lateral branches, usually smaller than the longitudinal filaments. Subfamily UDOTOIDEAE. 2. 2. Frond terminating in a penicillate tuft of free filaments. 2. Frond not terminating in free filaments. 3. 3. Frond of a branching series of disks. 7. HAUMEDA. 3. Disks terminal or wanting. 4. 4. Frond terminating in numerous flat expansions. 4. RHIPOCEPHALUS. 4. Frond not terminating in numerous flat expansions. 5. 5. No definite cortical layer. 2. AVRAINVII^LEA. 5. Cortex present either on stipe or lamina. 6. 6. Cortex of divaricate, labyrinthiform branches always present. • 6. CLADOCEPHALUS. 6. Cortex of lamina wanting, or of short, little divided branches. 5. UDOTEA. Subfamily CODIOIDEAE. i. CODIUM Stackhouse, 1795, p. XVI. Frond of spongy texture, of very varying form, consisting of branching, continuous filaments, their swollen ends, " utricles " closely packed to form a cortical layer ; sexual reproduction by zoogametes, produced in subovoid sporangia, borne laterally on the utricles ; large biciliate female gametes produced in spo- rangia with very dark green contents ; small biciliate male gametes produced in sporangia with yellowish contents; male and female usually produced on distinct individuals, but occa- sionally on the same individual ; by the union of the two sexes a zygote is produced, germinating immediately ; no asexual reproduction is known, but is probable that female zoospores sometimes germinate parthenogenetically. The species of Codinin here recognized are based either on ex- ternal form, which is more or less variable in each species, or on THE GREEN ALGAE OF NORTH AMERICA 387 the size of the utricles, which varies within quite wide limits. It is probable that when the genus is thoroughly studied, pres- ent arrangements will be considerably changed. KEY TO THE SPECIES OF CODIUM. i. Forming a continuous expanded incrustation. 2. i. Not forming a continuous expanded incrustation. 3. 2. Utricles usually 50-60 n, rarely 100 /u diam. i. C. adhaerens. 2. Utricles usually 125-200 fj., rarely 300 ^ diam. 2. C. difformc. 3. Frond globose to pyriforru. 3. C. Ritteri. 3. Frond branched, cylindrical or compressed. 4. 4. Frond creeping, attached by holdfasts. 4. C. repens. 4. Frond erect. 5. 5. All or part of the utricles rnucrouate. 9. C. mucronatum. 5. Utricles blunt, smooth. 6. 6. Branches usually constricted at base. 6. C. isthmocladum. 6. Branches not usually constricted at base. 7. 7. Frond normally cylindrical throughout; utricles seldom 200 fj. diam. 5. C. tomentosuin. 7. Frond normally more or less compressed. 8. 8. Utricles usually 400 /j. diam. or more. 7. C. elongatuui. 8. Utricles usual 1}- less than 250 /j.. 8. C. Lindenbergii, 1. C. ADHAERENS (Cabr.) Agardh, 1822, p. 457 ; Harvey, 1846-51, PL XXXV. A; P. B.-A., No. 523. Forming an ex- panded, incrusting layer, closely adherent to the substratum, dark green, lubricous, increasing by marginal growth, with rounded lobes ; the filaments and utricles united by firm gela- tine ; utricles clavate, 50-60, rarely ioO|udiam., sometimes with long, cylindrical lower part. On exposed rocks. Vancouver to Cal. Europe, Asia, Occanica. Forming a firm crust, about i cm. thick, on rocks ; quite dis- tinct from our other species, except C. difformc, which has a similar habit, but larger utricles. 2. C. DIFFORME Kutzillg, 1843, p. 300; 1856, PI. XXXV, fig. 99 ; Vickers, 1908, p. 22, PI. XXV. Habit like that of C. adhaerens; utricles 125-200, rarely up to 300 /j. diam. Fla., W. I. Mediterranean, warmer Atlantic, Pacific. Apparently a plant of wanner waters, while C. adhaerens ex- tends considerably farther north. 3. C. RITTERI Setchell and Gardner, 1903, p. 231, PI. XVII. Frond globose to pyriform, up to 3 cm. high, attached by a dis- tinct stipe-like base, solid, the center consisting of a felt-like mass of fine filaments; utricles pyriform, blunt, 1.50-400 //, diam. older ones usually swollen in the middle, and with the mem- 388 TUFTS COLLEGE STUDIES, VOL. II, No. 3 brane at the tip somewhat thickened at the central part and projecting inwards. Alaska to Vancouver. Nearest allied to C. mamillosnm Harv., but that species has balloon-shaped utricles, 1-2 mm. diam. 4. C. REPENS Crouan in Vickers, 1905, p. 56; 1908, p. 23, PI. XXIX ; C. tcnuc var. repens Crouan in Maze and Schramm, 1870-77, p. 107. Branching like that of C. tomcntosnm but branches prostrate and entangled, attaching themselves to the substratum by short special branches; utricles 150-300 ^ diam. On rocks at low tide. Barbados, Guadeloupe. 5. C. TOMENTOSUM (Huds.) Stackhouse, 1795, p. 21, PI. VII ; Harvey, 1846-51, PI. XCIII ; 1858, p. 29, in part ; Vick- ers, 1908, p. 22, PI. XXVI; P. B.-A., No. 168. Frond erect, cylindrical, dichotomously branched, more or less fastigiate, surface smooth and soft; utricles obovate-clavate, 100-150 p, rarely 200 p. diam., 3-6 diam. long., apex obtuse, unarmed. N. C. to Fla.; W. I. Europe, Asia, Africa, Oceanica. A cosmopolitan species, but many forms once included here have been removed, and it may be that a careful comparison would considerably reduce the number of localities for C. tomcn- tosnm. The principal distinctions from similar species are found in the cylindrical frond, and the unarmed tips of the utricles. 6. C. ISTHMOCLADUM Vickers, 1905, p. 57 ; 1908, p. 23, PI. XXVIII. Frond dichotomously branched, the branches usu- ally constricted at the base ; utricles 200-300 p. diam. Barba- dos, Guadeloupe. 7. C. ELONGATUM Agardh, 1822, p. 454; Vickers, 1908, p. 22, PI. XXVII; P. B.-A., No. 627. Frond dichotomously branched, often much elongate, younger divisions terete, older compressed, especially below the dichotomies, being there dis- tinctly cuneate ; utricles obovate-clavate, 300-400 ^ diam., 5-6 times as long as the greatest diam. N. C. to Fla., W. I. Europe, Africa, So. America. The younger plants resemble C. tomcntosum, but the flatten- ing is marked in older plants ; in some cases all parts except the younger tips are quite broadly cuneate. 8. C. LINDENBERGII Binder in Kiitzing, 1856, p. 34, PI. XCVII ; P. B.-A., No. 628. Frond di- polychotomous, com- pressed or flat in all parts, segments cuneate, terminal linear- lanceolate ; utricles clavate, 80-150^ diam., 3-4 times as long- as the greatest diam. Cal. Africa. The fronds in this species are sometimes triangular or reni- THE GREKN ALGAE OF NORTH AMERICA 389 form and undivided ; an extreme much beyond anything in C. elongation ; for ordinary forms the difference in size of utricles is sufficient distinction. 9. C. MUCRONATUM J. G. Agardh, 1886, p. 43. Frond cylindrical, more or less regularly dichotomously fastigiate, sur- face more or less roughish ; utricles cylindric-clavate, 5-10 diam. long, terminating in a distinct mucro. As described by Agardh, this species is divided between three varieties, with no definite typical form ; it seems to take a place in the Pacific the same as that occupied by C. tomcntositm in the Atlantic, and it is probable that most, if not all reports of the latter from the Pacific, really refer to this species. Var. CALIFORNICUM J. G. Agardh, 1886, p. 44, PI. I, fig. 3; P. B.-A., No. 229. Utricles in younger parts of the frond cylindrical, ending in a very acute mucro ; in the older parts clavate, with a blunter mucro. Fig. 144. Alaska to Mexico. Var. NOVAE ZELANDIAE J. G. Agardh, 1886, p. 44. Utricles in younger parts subcylindrical, with a short mucro ; in older parts clavate, mucro wanting or very inconspicuous. Van- couver. N. Zealand. In var. californiann the mucronate utricles are so well devel- oped that the surface of the frond appears, even to the naked eye, not so smooth as that of C. tomcntosidn. In var. novae zclandiac they are much less noticeable, and some care is re- cp:iired to distinguish this variety from C. tomentosum. 2. AVRAINVILLEA Decaisne, 1842, p. IDS. Fronds not calcified, sessile or stipitate, coarse, greenish, brownish or blackish, composed of inarticulate, cylindrical or moniliform, dichotomous, interwoven filaments, terminating above in a somewhat flabelliform expansion or in digitate lobes, below in a mass of rhizoids or a rhizome ; chromatophores mi- nute, rounded or fusiform, usually with a pyrenoid ; reproduc- tion by aplanospores (?) formed in small number in sporangia terminal on short branches projecting from the surface. A tropical genus of coarse, unsightly algae, growing abun- dantly in muddy shallow water, but extending also to consider- able depths. KEV TO THR SPECIES OF AVRAIN-VILLEA. i. Upper part a distinct flabellutn. 2. i. Upper part digitately lobed. i. A.Raivsoni. 390 TUFTS COLLEGE STUDIES, VOL. II, No. 3 2. Surface of flabelluni smooth or smoothish. 3. A. Icris. 2. Surface of flabelluni velutinous, spongy or strigose. 3. 3. Interior filaments of flabelluni inoniliforni. 2. A. nigricans. 3. Interior tilanieuts of flabelluui cylindrical with basal constrictions. 4. A. loiigicatilis. 1. A. RAWSONI (Dickie) Howe, 1907, p. 510, PI. XXX; P. B.-A., No. 1481. Frond formed of more or less dense, terete, clavate or fusiform, digitate lobes, not developing a flabelluui ; filaments cylindrical to subtorulose, always strongly constricted just above a dichotomy, rather thin-walled, 30-70 /x diam.; color rather light green when growing, brownish or blackish when dried. W. I. The digitately lobed frond, much resembling some of the common digitate sponges, sufficiently distinguishes this from our other species. The material distributed in P. B.-A., No. 770 as A. longicaulis and No. 771 as A. nigricans, was largely A. Rawsoiii, but also with some A. nigricans, as now defined. 2. A. NIGRICANS Decaistie, 1842, p. 96; Howe, 1907, p. 508, PI. XXVIII, figs. 8-25 ; A. /ono-icaitlis Murray and Boodle, 1889, p. 70, PL CCLXXXVIII, figs. 1-5. Flabelluni suborbic- ular to cuneiform, irregularly and obtusely lobed ; coriaceous, sessile or stipitate, from a more or less distinct subterranean rhizome ; filaments very regularly moniliform ; those of the in- terior 50-70 p. cliam., near the surface about 30 /A, with closer set constrictions ; sporangia clavate to globose, 350-800X200-350 // ; spores ovoid, pyriform, or elongate-ellipsoidal, 130-300X66-120 //.. Color dark brown or blackish. W. I., Fla. Brazil . A coarse and unsightly plant, forming dense growths under the surface of the mud in shallow sheltered waters ; the tuber- like rhizome is usually infested with many minute animals. The texture of the flabelluni is quite loose, not entirely opaque when held against the light. Forma FULVA Howe, P. B.-A., No. 1480. Flabelluni thicker, more spongy ; stipe flatter, broader and less differentiated ; fila- ments coarser, less regularly moniliform, more frequently and divaricately forked ; color more yellowish. With the type. The sporangia noted above for this species were found on an individual of iormafulva. 3. A. LEVIS Howe, 19053, p. 565, PI. XXIII, fig. i ; PI. XXVI, figs. 8-10 ; P. B.-A., No. 1478; A. sordida Murray and Boodle, 1889, p. 70.* Flabelluni cuneiform-obovate to reni- * A. asarifolia Borgesen, 1908, p. 34, fig. 4, PI. Ill, is hardly to be dis- tinguished from A. levis ; the specimens of the latter distributed as P. B.-A., No. 1478 are not at the fullest development, but other specimens . THE GREEN AIr agree. 3. V. ORNITHOCEPHALA Agardh, 1817, p. 49; P. B.-A., No. 984; V. scricea Walz, 1866, p. 150, PI. XIII, figs. 20 and 21 ; Wolie, 1887, p. 150, PI. CXXVII, figs. 12 and 13. Fila- ments 35-45 M diam., oogonia 2-6-seriate, unilateral, obliquely ovoid, 100-150 n diam., i}4 diam. long, opening through a broad beak, sessile or very short-pedicelled and in form not un- like a bird's head ; oospore nearly globose, about as wide as the oogonium, but not filling it longitudinally, reddish when ripe, with triple membrane; antheridia one or two at one end of a series of oogonia, cylindric to subclavate, 20-25 /"• diam., about 4 diam. long, bent nearly horizontally; zoospores 83-iooX 90-115^, in cylindrical or very slightly clavate sporangia; the cilia much more closely set at the forward end. Occurs mostly in running water. Mass., Pa. Europe. The seriate oogonia with their birds' heads facing the anther- idium at one end, make a pretty good mark for distinguishing this from species hitherto reported in America, but the same characters are found in the European V. polysperma Hassall, which very likely will sometime be found here. It is more slender throughout, the filaments 22-33 //., the oogonia 60-65 P- diam., and more nearly erect ; zoospores 66-88 //. diam.; anther- idium always single. 4. V. AVEKSA Hassall, 184^, p. 429 ; 1845., p. 54, PI. VI, fig. 5; Walz, 1866, p. 151. PI. XIII, figs. 25 and 26; PI. XIV. fig. 27 : Wolk-, 1887, p. 149, PI. CXXVII, figs. 5-8; P. B.-A., Xo. 475. Filaments 60-100 ^ diam.; oogonia obliquely ovoid, ^ile or shortly stipitate, two, rarely more in a series, the beaks usually in opposite directions, mostly erect, 125X250 /A ; THE GREEN ALGAE OF NORTH AMERICA 425 oospore globose or ovoid, with triple membrane, 75-100 /u. diam., not filling the oogonium ; antheridia cylindric or subclavate, 30-40 p. diam., erect, more or less incurved, on each side, of the series of oogonia. In ponds and ditches. Mass., Conn., Neb., Cal. Europe. The distinguishing mark for this species is found in the oogonia facing in opposite directions. 5. V. DICHOTOMA (I/.) Agardh, 1817, p. 47; Walz, 1866, p. 152, PI. XIV, figs. 28-33; Wolle, 1887, p. 149, PI. CXXVI, figs. 1-7; Wittr. and Nordst., Alg. Exsicc., Nos. 337, 338. Dioecious, filaments 135-200 /x diam., oogonia sessile, 300-400 /A diam., globose or ovoid-globose, distant or 2-6 approximate; ripe oospore with triple membrane, brown spotted ; antheridia erect, ovoid, 90- 1 50 X 150-250 p.. In ponds and ditches. W. I. E '21 rope. Recorded by Wolle without definite locality. V. Pi/us Wolle, 1887, p. 153, PI. CXXVII, figs. 1-4, from Vt., may be a form of this species. 6. V. REPENS Hassall, i843b, p. 430; 1845, p. 52, PI. VI, fig. 7; Gotz, 1897, p. no, figs. 14-16. Filaments 33-50 ^ diam. ; oogonia single, rarely two, sessile, obliquely ovoid, 70-80X55-80 /A, ending in a short beak, usually horizontal; oospore quite filling the oogonium, grayish, coarse grained, with triple membrane and one or more brown spots ; antherid- ium close to the oogonium, circinate, on a straight or curved pedicel; zoospores 80-130X75-120 /tx, formed in nearly cylindri- cal sporangia ; cilia uniformly distributed. On moist ground or submerged. Cal. Europe. 7. V. SESSILIS (Vauch.) De Candolle, 1805, p. 63 ; Kiitzing, 1856, PI. LIX, fig. 2 ; Wolle, 1887, p. 151, PI. CXXVII, figs. 9-11; Gotz, 1897, p. in, figs. 17-22; P. B.-A., No. 228. Fil- aments 50-85 fj.dia.rn.; oogonia usually two, sometimes single, sessile, ovoid or oblong-ovoid, 70-85X75-100 p., more or less oblique, with short beak ; antheridium between the oogonia or beside the single oogonium, on a short pedicel, straight, hooked or circinate ; ripe oospore dark-spotted, \vith triple membrane, filling the oogonium ; zoosporangia ovoid-clavate, terminal on a branch which is however sometimes so short that the spor- angium appears sessile; zoospores 110-145X110-125 /«, with cilia evenly distributed. Me., Mass., R. I., Conn., N. J., Neb., Alaska to Cal. Europe. A common species in brooks and ditches. 8. V. ORTHOCARPA Reinsch, 1887, p. 189, PI. VIII ; V. da- 426 TUFTS COLLEGE STUDIES, VOL. II, No. 3 vata Gotz, 1897, p. 114, figs. 23-28; an Ectosperma . clavata Vaucher ? Filaments 77-110 /u. diarn.; oogouia one or two, ses- sile, 55-75X80-110 /A, narrowly ovoid, erect, with a short and broad vertical beak ; . oospore of same shape, 50-65X65-90 /* with a red central spot and triple membrane ; autheridium soli- tary beside a single oogonium or between two oogonia, circi- nate, on a straight or recurved pedicel; zoospores I25-I5OX 135-175 M, in broadly clavate sporangia ; cilia uniformly distrib- uted. In ponds and ditches. Cal. Europe. The three species, V, repens, V. sessilis and V. orthocarpa are certainly closely related, but Gotz, who has studied them more than any other observer., considers them distinct. Beside the differences in dimensions of filaments and dimensions and shape of oogonia, he notes physiological characters, which it is not practicable to give here in detail. As far as Vaucher's descrip- tion of Ectosperma clavata goes, it would seem to apply to any zoosporiferous Vaiicheria ; Gotz does not state why he identi- fies E. clavata with V. orthocarpa Reinsch, except that the sex- ual organs in his plant agree with Reinsch 's description and plate ; but Yaucher knew the zoospores only. 9. V. HAMATA (Vauch.) De Candolle, 1805, p. 63; Walz, 1866, p. 148, PI. XII, figs. 12-16; Wolle, 1887, p. 152, PL CXXVIII, figs. 8-10. Filaments 40-60 /j, diam., oogonia soli- tary, 75-90X60-75 p., ovoid to convex-concave, borne on the shorter division of an apparently forking branch ; the longer division recurved, bearing the hooked or circinate antheridium ; or an oogonium on each division, the antheridium between ; an- theridium in a plane at an angle to that of the oogonium ; oospore closel}7 filling the oogonium, with quadruple membrane and a dark brown or blackish central spot ; the membrane of the oogonium falling with the oospore, but not gelatinizing ; aplanospores formed in terminal, somewhat clavate sporangia, when ripe ejected from the latter. On moist ground or sub- merged. Washu., Cal. Europe. 10. V. TERRESTRis (Vauch.) De Candolle, 1805, p. 62 ; Walz, 1866, p. 149, PL XIII, figs. 18 and 19; Wolle, 1887, p. 153, PL CXXIX, figs. 1-8; P. B.-A., No. 78. Filaments 50-80 fj. diam.; oogonium usually solitary, 85-125X60-100 /*, lat- eral on a short branch, on the summit of which is the curved or circinate antheridium, about 20 /JL diam.; oospore globose to plano-convex, with quadruple membrane and numerous brown- ish spots ; the membrane of the oogonium remaining attached to the oospore and falling with it, gelatinizing and ultimately THE GREEN ALGAE OF NORTH AMERICA 427 disappearing. Though the antheridium is really terminal, it is often pushed aside by the oogonium, and appears to be lateral, below the oogonium. On moist ground or submerged, common. Greenland, Mass., Neb., Cal. Europe. There is considerable resemblance between V. terrestris and V. hainata, but in the former the fruiting branch is short, the oogonium practically sessile on the pedicel of the antheridium ; in the latter the fruiting branch is usually longer and the oogo- nium and the antheridium are on distinct pedicels, appearing as if the branch had forked ; the manner of disappearance of the oogonium membrane is different ; aplanospores are not known in I', terrestris, though it is the commoner species. ii. V. GEMINATA (Vauch.) De Candolle, i8o5,.p. 62; Walz, 1866, p. 147, PI. XII, figs. 7-11; Wolle, 1887, p. 151, PL CXXVIII, figs. 1-3; P. B.-A., No. 1287. Filaments 50-100^ diarn. ; oogonia 2, 70-90X60-75 /u,, ellipsoid-hemispherical to convex-concave, shortly stipitate near the end of a short branch; the antheridium between them, cylindrical, hooked or circinate ; ripe oospore brown-spotted with triple membrane, filling the oogonium ; aplanosporangia either on the same frond as the oogonia or on separate individuals, aplanospores 1 20-200 X 120-190 ^u,, formed in ovoid sporangia usually terminating short, lateral branches, freed by the dissolution of the membrane ; akinetes formed by the breaking up of portions of the filaments into short, thick-walled cells, whose development varies consid- erably, according to circumstances. Common in quiet or slowly running water. Greenland, Me., Mass., N. J., Neb., Cal. Europe. Var. RACEMOSA (Vauch.) Walz, 1866, p. 147; P. B.-A, No. 268. Oogonia 3-many, smaller than in the type, corymbosely arranged about the antheridium. Vt., Mass., N. J., Neb., Washn., Cal. Europe. The variety differs from the type only by the greater number of oogonia, and there is no sharp division ; plants representative of each can often be found in the same tuft ; the variety seems to be more abundant than the type.* *Gbtz, 1897, p. 124, includes under V. racemosa what is above included under both ]'. go/iinata and var. racemosa; and at p. 126 applies the name V. geminata to what appears to be quite a different plant, and to judge by the descriptions and figures a good species ; but why it should bear the name of V. geminata is not so clear. His fig. 45, shows a quite regular ovoid spore ; Vaucher says that the spores of Ectospermagemin- ata " au lieu d'etre arrondics, representent une portion de sphere forte- 428 TUFTS COLLEGE STUDIES, VOL. II, No. 3 12. V. LONGIPES Collins, 1907, p. 201, PL L-XXVI, fig. i. Filaments 80-90 /u, diam., oogonia and antheridia borne at the end of a branch one to several mm. long, 30-40 //. diam. ; antheri- dium terminal, cylindrical or slightly tapering, hooked or cir- cinate ; oogonia 70-85X35-40 /A, ovoid, slightly oblique, 2-4, on pedicels 20-30 /A diani., 100-150 p. long, arising a little below the antheridium, and usually surpassing it. In brooks and pools. Cal. Somewhat resembling V. geminata, but distinct by the very long fruiting branches, at right angles to the filaments, as well as by the longer pedicels of the oogonia. 13. V. GARDNER: Collins, 1907. p. 201, PL I/XXVI, figs. 2 and 3 ; P. B.-A., No. 1288. Filaments 50-70 /* diam., sparingly branched, branches mostly at right angles ; antheridia and oogonia borne on pedicels of about the same size, 60-100 p. long, 15-20 p. diam., arising from the same point on the filament ; antheridium solitary, terminal on the central, vertical pedicel, less commonly 2 or 3 on independent pedicels, hooked or cir- cinate, tapering to 10 ^ diam. ; oogonia 2-4, occasionally more, 85-95X60-70 //., quite oblique, often concave on the inner side, on opposite sides of the antheridium or encircling it, their pedi- cels at about 45 degrees to the filament ; usually surpassing the antheridium. In brooks and pools. Fig. 153. Cal. In general arrangement like V. longipes, but the pedicels bearing the organs of fructification are placed directly on the filament, radiating from one spot ; the oogonia are much more oblique, often concave inside. Forma TENUIS Collins, 1907, p. 201. Filaments 30-40 /A diam. ; antheridia often more numerous than the oogonia ; oogonia sometimes single. With the type. Cal. When in this species two oogonia occur with one antheridium, there is a certain resemblance to V. geminata ; but the slender radiate pedicels make it amply distinct ; the forms with many oogonia and antheridia are quite unlike anything else. The largest number of pedicels observed in a group is 12, four bear- ing antheridia, eight oogonia. merit echancree a 1'interieur." Figures 43 and 44, V. racenwsa, have spores quite like this description. The filaments of E. geminata, accord- ing to Vaucher, are about half the size of those of E. sessilis ; while according to Gbtz the two species are of about the same size, lr. geminata slightly larger. There is no indication in the descriptions and figures of Vaucher and Hassall of the lateral prolongations of the antheridium characteristic of Gbtz' plant. If the latter were to be identified with any of Vaucher's species, E. cruciata seems more probable than E. geminata, except that it is said to be quite small in all of its dimensions. THE GREEN ALGAE OF NORTH AMERICA 429 14. V. PILOBOLOIDES Thuret in Le Jolis, 1863, p. 65, PI. I, figs. 4 and 5 ; Worouin, 1869, p. 153, PI. II, figs. 18-29; P- B.-A., No. 476. Marine; filaments usually 40-60 // diam., sometimes 80 /j. ; antheridium terminal, separated from the fil- ament by an empty cell, cylindrical, acute, with one or two lateral, conical projections ; oogonium terminal, usually on a short branch near the antheridium, clavate with a spherical summit, up to 200 //. diam. ; oospore lenticular with thin mem- brane, 150X80-100 /u. ; aplanospores 250X80 /x., formed at the ends of the branches, expelled from the sporangium at maturit)7. Muddy and sandy places, below low water mark. Conn. Var. COMPACTA Collins, 1900, p. 13; P. B.-A., No. 477. Tufts very densely matted ; oospores usually spherical, occa- sionally lenticular ; oogonia and antheridia scattered without definite relation to each other. Salt marshes, on mud near high water mark. Mass. The dense, plush-like coatings of this variety are indistin- guishable from V. Thitretii, that grows in similar locations ; but the fructification is quite distinct. 15. V. SPHAEROSPORA Nordstedt, i878a, p. 177, PI. II, figs. 7 and 8 ; Phyk. Univ. , No. 282. Marine; filaments 25-60 /j. diam., loosely tufted ; antheridium at the somewhat swollen end of a branch, generally slightly curved, acuminate, bearing just below the summit two conical, subopposite processes ; oogonium below on the same branch, separated by an empty cell, globose or obovoid-globose, 105-135 /u. diam. ; oospore green, with thin membrane, 85-125 p. diam., not filling the oogonium. Green- land. Northern Europe. 16. V. INTERMEDIA Nordstedt, ,1879, p. 179, PI. I, figs. 10-16 ; Wittr. & Norclst., Alg. Exsicc., No. 334. Marine; fila- ments 35-65 fj. diam. ; oogonia subsessile or shortly pedicelled, globose or ovoid-globose, 90-130 /* long, 95-115 ^ wide, with one short and broad tube ; antheridium single or often two, 20-30 //. diam., usually straight with rounded, truncate apex, and 2-4 very short, lateral tubes; oospore globose, with thin membrane, 85-120 /u. diam., almost filling the oogonium. Greenland. Northern Europe. 17. V. CORONATA Nordstedt, 1879, p. 177,- PI. I, figs. 1-9; Wittr. and Nordst., Alg. Exsicc., No. 1022. Marine; filaments 48-70 p. diam. ; oogonia solitary, subsessile, borne on the branches bearing the antheridia, more rarely on the main filaments, obovoid or obliquely ovoid, 125-145 /u. long, 145-180 p. wide, bearing at the top a circle of 3-6 tubes for the entrance of the spermatozoids ; oospore globose or subglobose, 115-135X115- 430 TUFTS COLLEGE STUDIES, VOL. II, No. 3 145 /A, not quite filling the oogonium ; ripe oospore \vith occa- sional brown spots, and thick, minutely pitted membrane ; antheridium straight with rounded apex, at the end of the branch bearing the oogonium, single, or oftener two, 30-40 ^ diain., separated from the branch by an empty cell ; with one apical tube. Greenland. Northern Europe. 18. V. LITOREA Agardh, 1821^.463; Nordstedt, 1879, p. 1 80, PI. II, figs. 1-6; Farlow, iSSi, p. 105; P. B.-A., No. 166. Marine, dioecious; filaments 70-95 /u, diam.; antheridium at the end of a longer or shorter branch, supported by an empty cell, cylindrical, rather obtuse, with 2-4 short, lateral projections ; oogonium at the extremity of a reflexed branch, clavate or obovoid, about 200 /u, wide and 300-400 fj. long ; separated from the filament by a short, empty cell; oospore subglobose, with thick membrane, 180-250 //. diam., occupying the upper part of the oogonium. Mass, to 1ST. J. Europe. A coarse, dingy plant, with long filaments forming loose tufts, on mud and gravel at low water mark.* DICHOTOMOSIPHON Ernst, 1902, p. 115. Frond filamentous, inarticulate, multinucleate, with disk- shaped chromatophores without pyrenoid ; filaments di-poly- chotomous, attached below by slender, colorless rhizoids ; branches constricted at base to about half the diameter ; similar constrictions formed at intervals between the branchings ; mem- brane thickened at the constrictions, often becoming brown ; starch accumulation in large quantities throughout the frond. Sexual reproduction by terminal oogonia and antheridia ; oospore globose, with triple membrane, germinating after a resting period. Asexual reproduction by akinetes, in the form of tubercular swellings at the ends of the branches, or oftener on special lateral branches, germinating after a resting period. This genus differs from Vauchcria by the true dichotomous branching, the peculiar asexual reproduction, the corymbose arrangement of the sexual organs, the presence of starch in large quantity, and the tendency to articulation shown by the constrictions. While the sexual fructification, except as to the position of the organs, is the same as in / 'aitchcria, the vegetative characters are curiously like those of some of the marine Codiaceae ; when a Udotea, for instance, is decalcified, the fila- *V. vclntina Wolle, 1887, p. 153, is given merely from older references. X'vunlinsjf to Varlow, 1881, p. 105, a specimen from J. W. Bailey, marked by him / '. I'ditt hia, is probably V. Tliui ctii Worouiu. THE GREEN ALGAE OF NORTH AMERICA 431 ments are in many cases like those of Dichotomo siphon. As far as vegetative structure is concerned, there would seem to be a definite phylogenetic series from Dichotomosiphon through Avrainvillea, Pcnicillus, Rhipocephalus and Udotca to Halimeda ; but while the reproductive organs of Dichotomosiphon are of high rank, those of Halimeda are much lower and of a different type, and practically nothing is known as to the reproduction of the intermediate genera. If any of these genera should ever be found to have fructification resembling that of Dichotomosiphon, or if sporangia like those of Halimeda were found in/?, pusillus, the latter would have to be considered as the primary form of the Codiaceae or at least of the Udotoideae, from which the other forms had developed. There is one well known fresh water species, to which a marine form is now doubtfully added. KEY TO THE SPECIES OF DICHOTOMOSIPHON. i. Filaments 40-100 n diam. ; freshwater. i. D. fuberosus. i. Filaments 10-30 M diam. ; marine. 2. D. pusilliis. 1 . D. TUBEROSUS (A. Braun) Ernst, 1902, p. 115, Pis. VI-X ; Vaiicheria tubcrosa A. Braun in Kiitzing, 1856, p. 23, PI. LXV ; Wolle, 1887, p. 154, PI. CXXIX, figs. 9-14, Pl/CXXX ; P. B.-A., No. 764. Fronds 2-10 cm. long, 40-110 /u, diam., usually 70-95 /u. ; akinetes straight and elongate or clavate and curved, 0.5-5 mm. long, 200-400/1* diam. ; antheridia and oogonia cor)rm- bosely arranged at the ends of the ultimate divisions ; antheridia cylindrical or clavate, more or less incurved, 130-170X35-50/11 ; oogonia globose, 290-320 p. diam. ; oospore globose, dark green, 250-280/11 diam. Fig. 158. Ont., Pa., Mich., 111., Ga., Texas. Europe. This species occurs in similar localities to \\nteheria; it appears to be more common in America than in Europe, where it is reported only from Switzerland. In P. B.-A., No. 764-, the oogonia are large enough to be .seen by the naked eye, but are erroneously referred to in the label as " tuber-like swellings." Wolle's varieties intermedia and minor are merel)7 smaller, sterile forms. 2. D. pusillus n. sp. Filamentis prostratis, irregularibus, 10-30 p. diam., hinc et illinc constrictis, di- trichotomis ; ramis basi fortiter constrictis, apice et sub clichotomiis saepe clavifor- miter distentis ; ramis lateralibus brevibus et simplicibus fre- qucntis, sine ordine egredientibus, raro oppositis. Filaments prostrate, irregular, 10-30 p. diam., here and there 432 TUFTS COLLEGE STUDIES, VOL. II, No. 3 constricted, di- trichotomous ; branches strongly constricted at the base, often clavately swollen at the end or when forking ; lateral branches also common, usually short and simple, occa- sionally opposite. In shallow water, in company with Bostrychia tend/a (Vahl) J. Ag., Lvngbya confcrvoidcs Ag., etc. Marine. \V. I. Nothing being known as to its reproduction, the inclusion of this plant in Dichotomo siphon is only provisional ; in vegetative characters the correspondence is marked. It forms rather dense mats on the surface of the Bostrychia, and appears to be common in Jamaica and other West India islands. The filaments in the under part of the mats are colorless as in Vauchcria ; at first glance one is reminded of the simpler forms of Udotca minima Ernst, 1904, PI. VII, figs, i-io, but though part of the plant is colorless, part bright green, there is no distinction in form between the two as in the Udotca, and both seem to remain prostrate. In a few instances there have been noticed short simple branches in three or four opposite, approximate pairs, with triangular outline, like the tip of a branch of Bryopsis plnmosa, but this may have been accidental ; there was nothing to indicate that it was a distinct erect growth. The constrictions at the base of the branches are strongly marked, with stratified thickening inside the wall ; the constrictions in the filaments may be distant, or they may be scarcely more than one diameter apart, when the frond appears markedly moniliform. The following species was omitted from the proper place, p. 183 of this work. ULOTHRIX SCUTATA Jonsson, 1904, p. 57, figs. 8 and 9. Filaments attached by a basal disk, with even or lobed margin ; lower cells 5-6 /A diam., 1-3 diam. long; upper cells 9-16 p. diam., ys-i diam. long; chromatophore zonate, not occupying the whole length of the cell, with one pj-renoid. Filaments with more or less distinct constrictions, at intervals of about 4 cells. Greenland. The basal disk characteristic of this species is iisually sepa- rated from the rest of the basal cell by a sharp constriction ; in addition to the disk, the filaments are often attached by rhi- zoids to the substratum, fronds of THE GREEN ALGAE OF NORTH AMERICA 433 LIST OF WORKS TO WHICH REFERENCE IS MADE Agardh, C. A. 1810. Dispositio algarum Sueciae, Part i. Lund. 1812. Dispositio algarum Sueciae, Parts 2 and 3. Lund. 1814. Algarum decas tertia. Lund. 1817. Synopsis algarum Scandinaviae. Lund. 1820. Icones algarum ineditae. Fasciculus primus. Lund. 1821. Icones algarum ineditae. Fasciculus secundus. Stockholm. 1822. Species algarum rite cognitae, Vol. I, part 2. Lund. 1824. Systema algarum. Lund. 1827. Aufzahlung einiger in oestreichen Landern gefunde- nen neuen Gattungen und Arten von Algen. Flora, Vol. X, p. 625. 1828. Species algarum rite cognitae, Vol. II. Greifs- wald. 1828-1835. Icones algarum Europearum. Leipzig. Agardh, J. G. 1842. Algae maris Mediterranei et Adriatic!. 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Histoire des conferves d'eau douce. Geneva. Vickers, Anna. 1905. Liste des algues marines de la Bar- bade. Ann. Sci. Nat., Ser. 9, Bot., Vol. I, p. 45. 1908. Phycologia Barbadensis. Paris. Wallroth, F. W. 1815. Annus botanicus, sive supplementum tertium ad C. Sprengelii floram Halensem. 1833. Compendium florae germanicae, IV. Nuremburg. Walz, J. 1866. Beitrag zur Morphologic und Systematik der Gattung Vaucheria. Prings. Jahrb., Vol. V, p. 9. Warming, E. 1876. Ein vierzelliges Gonium. Bot. Tids- skrift, Ser. 3, Vol. I, p. 69. Weber-Van Bosse, Anna. 1898. Monographic des Caulerpes. Ann. Buitenzorg, Vol. XV, p. 243. West, G. S. 1901. The alga flora of Yorkshire. Trans. Yorkshire Nat. Union, part 22, etc. 1904. A treatise on the British freshwater algae. Cam- bridge. 1905. West Indian fresh water algae. Jour, of Bot., Vol. XLII, p. 281. 1908. Some critical green algae. Jour. Linn. Soc., Bot., Vol. XXXVIII, p. 279. West, W. and G. S. 1895. On some fresh water algae from the West Indies. 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Bidrag til Sydamerikas algflora. Bih. Kgl. Svensk. Vet.-Akad. Handl. Stockholm, Vol. VIII, No. 18. 1887. Algologische Mittheilungen. Prings. Jahrb., Vol. XVIII, p. 425- 1897. Chlorophyceae, in Engler and Prantl, Natiirlichen Pflanzen-familien, Teil I, Abt. 2. 1898. Mittheilungen a us der biologische Gesellschaft zu Christiania. Biol. Centralb., Vol. XVIII, p. 302. 1899. Newformsof green algae. Rhodora, Vol. I, p. 149. iSgga.. Botaniska Notiser, p. 281. 1901. Studien iiber Chlorophyceen, I-VII. Biol. Station Drobak Vidensk. Skrifter, 1900, No. 6. 1903. Algologische Notizen. Nyt Mag. Naturvidenskab., Vol. XLI, p. 109. Wittrock, V. B. 1866. Forsok till en Monographi ofver algslagtet Monostroma. Upsala. 1868. Bidrag till kannedomen Sveriges Zygnemaceer och Mesocarpaceer. Bot. Notiser, p. 190. 1870. Dispositio Oedogoniacearum Suecicarum. Ofv. Kgl. Vet.-Akad. Forh. Stockholm, Vol. XXVII, No. 3. * 454 TUFTS COLLEGE STUDIES, VOL. II, No. 3 1872. Om Gotlands och Oelands sotvattenalger. Bill. 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Desmids of the United States, New Edition. Beth- lehem. Wood, H. C. 1869. On Oedogonium Huntii. Proc. Amer. Phil. Soc., Vol. X, p. 333. i869a. Prodromus of a study of the fresh water algae of eastern North America. Proc. Amer. Phil. Soc., Vol. XI, p. 119. 1872. A contribution to the history of the fresh water algae of North America. Smithsonian Contrib. Knowledge, Vol. XIX. THE GREEN ALGAE OF NORTH AMERICA 455 Woronin, M. 1869. Beitrag zur Kentniss der Vaucherien. Bot. Zeit., Vol. XXVII, p. 137. Wright, E. P. 1881. On Blodgettia confervoides. Trans. Royal Irish Acad., Vol. XXVIII. Yendo, K. 1903. Three species of marine Ecballocystis. Bot. Mag. Tokyo, Vol. XVII, p. 199. Zanardini, G. 1858. Plantarum in mari rubro hucusque col- lectarum enumeratio. Mem. I. R. Inst. Venet., Vol. VII, p. 209. EXSICCATAE. Areschoug, J. E. Algae Scandinavicae exsiccatae. Upsala. Collins, F. S., Holden, I., and Setchell, W. A. Phycotheca Boreali-Americana. Maiden. Desmazieres, J. B. H. J. Plantes cryptogames de France. Lille. Farlow, W. G., Anderson, C. L. and Eaton, D. C. Algae Am. Bor. Exsiccatae. Cambridge. Harvey, W. H. Ceylon Algae. Dublin. Hauck, F. and Richter, P. Phycotheka Universalis. Trieste and Leipzig. Hohenacker, R. F. Algae marinae siccatae. Esslingen. Kiitzing, F. T. Algarum aquae dulcis germanicarutn decades. Halle. Le Jolis, A. Algues marines de Cherbourg. Cherbourg. Rabenhorst, L. Die Algen Sachsens resp. Europa's. Dresden. Roumeguere, C. Les Algues fluviales et terrestres cle France. Toulouse. Tilden, Josephine E. American Algae, Centuries I-VI. Min- neapolis. Wittrock, V. and Norstedt, O. Algae aquae dulcis exsiccatae. Upsala and Stockholm. Wittrock, V., Nordstedt, O. and Lagerheim, G. Algae aquae dulcis exsiccatae. Lund. Wyatt, Mary. Algae Danmonienses. Torquay. 456 TUFTS COLLEGE STUDIES, VOL. II, No. 3 EXPLANATION OF PLATES. PLATE I. 1. Botrydiopsis eriensis, after Snow. 1000 ", i. 2. Ophiocytium majus, after Nageli. 500 X i. 3. Chlorobotrys regularis, after West. 350 X i. 4. Conferva bombycina, after West. 750 X i. 5. Botr5rdium granulatum, after West. 15 X i. 6. Characiopsis minuta, after West. 350 X i. 7. Zygnema stellinum, with spores, after West. 300 X i. 8. Spirogyra protecta, with spores, after Petit. 250 X i. ga. Debarya glyptosperma, conjugating ; gb, with ripe spores ; after De Bary. 250 X i. 10. Zygogonium ericetorura, conjugating, after De Bary. 400 : i. 11. Gonatonema ventricosuin, with spores, afterWest. 800 X i. PLATE II. 12. Mougeotia viridis, with spores, after De Bary. 1000 X i. 13. Chlamydomonas angulosa, after Dill. 1000 ; ; i. 14. Haematococcus pluvialis, after Hazen. 700 X i. 15. Chlorogonium euchlorum, after Stein. 1000 X i. 1 6. Gonium pectorale, after Migula. 600 ) ; i. 17. Pandorina Morum, after Pringsheim. 700 X i. 1 8. Pleodorina illinoisensis, after Kofoid. 500 X i. PLATE III. 19. Platydorina caudata, face view, after Kofoid. 500 X i. 20. Platydorina caudata, side view, after Kofoid. 300 ; ; i. 21. Eudoriua elegans, after Gobel. 300 X i. 22. Volvox globator, after Oltmanns. 300 X i. 23. Palmella miniata, after Nageli. 400 " i. PLATE IV. 24. Botryococcus Braunii, colony dividing, after West. 600 X i. 25. Inerfigiata neglecta, after West. 700 X i- 26. Tetfaspora lubrica, after Nageli. 400 X i. THE GREEN ALGAE OF NORTH AMERICA 457 27. Apiocystis Brauniana, after Nageli. 250 X i. 28. Palmodactylon varium, young colony, after West. 125X1. 29. Prasinocladus subsalsus, after Davis. 600 X i. 30. Collinsiella tuberculata, after Setchell. 200 X i. 31. Chlorococcum humicola, after Nageli. 300 X i. 323. Trochiscia reticularis, after West. 400 X i. 32b. Trochiscia hirta, after West. 300 ] , i. 33. Chlorochytrium L,emnae, cells in different stages, in tissue of lyemna, after Klebs. 200 X i. 34. Rhodochytrium Spilanthidis, irregular^ shaped cell, after Lagerheim. 200 X i. 35. Chlorocystis Cohnii, on Enteromorpha, after Moore. 1000 X i. PLATE V. 36. Characium gracilipes, after Lambert. 500 X i. 37. Codiolum gregarium, after A. Braun. 100 X i. 383. Protosiphon botryoides, vegetative, after Klebs. 50 X i. 38b. Protosiphon botryoides, with aplanospores, after Klebs. 100 X i. 39. Eremosphaera viridis, section of cell, after Moore. 200X1. 40. Excentrosphaera viridis, section of cell, after Moore. 1000 X i. 41. Zoochlorella conductrix, in Hydra viridis, after Beyerinck. 600 X i. 42. Rhaphidium falcatum var. fusiforme, group of individuals, after Nageli. 300 X i. 43. Palmellococcus miniatus, with aplanospores, after Chodat. 800 X i. 44. Oocystis solitaria, after West. 800 X i. 45. Chodatella citriformis, after Snow. 1000 X i. 46. Nephrocytium Agardhianum, mother and daughter cells, after Nageli. 1000 X i. 47. Tetraedron trigonum, front and side views, after Nageli. 800 X i. 48. Cerasterias raphidioides, after Reinsch. 1000 X i. PLATE VI. 49. Thamniastrum cruciatum, after Reinsch. 500 X i. 458 TUFTS COLLEGE STUDIES, VOL. II, No. 3 50. Schizochlamys gelatinosa, recently divided cell, after West. 500 X i. 51. Elakatothrix americana, mother and daughter cells, after Snow. 800 X i. 52. Hormotila mucigena, after West. 500 X i. 53. Scenedesmus obliquus, after Nageli. 500 X i. 54. Crucigenia rectangularis, after West. 600 X i. 55. Selenastrum minutum, after Nageli. 1000 X i. 56. Kirchneriella lunaris, after Bohlin. 800 X i. 57. Coelastrum cambricum, after West. 800 X i. 58. Sorastrum spinulosum, after Nageli'. 500 X i. 59. Dictyosphaerium Ehrenbergianutn, after Nageli. 600 X i. 60. Dimorphococcus cordatus, after Wolle. 500 X i. 61. Dict}'ocystis Hitchcockii, after Wolle. 600 X i. 62. Hydrodictyon reticulatum, young colony in mother cell, after Klebs. 100 X i. 63. Pediastrum Boryanum, after Nageli. 800 X i. 64. Uiothrix zonata, vegetative, after Hazen. 300 X i. 65. Hormospora purpurea, after Wolle. 300 X i. PLATE VII. 66. Uronema confervicola, after Lagerheim. 800 X i. 67. Schizomeris L,eibleinii, after Hansgirg. 60 X i. 68. Microspora tumidula, akinetes in formation, after Hazen. 500 X i. 69. Stichococcus bacillaris, after Nageli. 800 X i. 70. Enteromorpha erecta, surface view, after Collins. 200X1. 71. Ilea fulvescens, surface view, after Collins. 200 X i. 72. Monostroma fuscum, cross section, after Collins. 200 X i. 73. Protoderma viride, surface view, after Rabenhorst. 600 X i. 74. Radiofilum apiculatuin, surface view, after Bohlin. SooX i 75. Ulva L,actuca, cross section, after Thuret. 300 X i. 76. Schi/.ogonium crenulatum, surface view, after Gay. 1000 X i. 77. Prasiola crispa, mature frond, after Oltmanns. 100 X i. THE GREEN ALGAE OP NORTH AMERICA 459 78. Gayella polyrhiza, multiseriate stage, after Rosenvinge. 500 X i. 79. Gayella polyrhiza, with rhizoids, after Rosenvinge. 500 X i. 80. Cylindrocapsa geminella, with oogonia, after Hansgirg. 300 X i. PLATE VIII. 81. Oedogonium fragile, with oogonia and antheridia, after Wittrock. 400 X i. 82. Bulbochaete intermedia, with oogonia and dwarf males, after Wittrock. 300 X i. 83. Microthamnion Kuetzingianum, after Hazen. 700 X i. 84. Stigeoclonium lubricum, after Hazen, 400 X i. 85. Chaetophora elegans, after Hazen. 400 X i. 86. Chlorotylium cataractaruui, branching filament, after Rab- enhorst. 400 X i. 87. Pseudendoclouium submarintim, after Wille. 1000 X i. 88. Endoclonium Moebiusianum, portion of disk, after Mobius. 600 X i. PLATE IX. 89. Draparnaldia glomerata, after Hazen. 300 X i. 90. Pilinia Morsei, after Collins. 400 X i. 91. Gongrosira deBaryana, after Rabenhorst. 300 X i. 92. Ochlochaete ferox, after Huber. 300 X i. 93. Dermatophyton radians, on and in shell of turtle, after Potter. 500 X i. 94. Epicladia Flustrae, after Reinke. 400 X i. PLATE X. 95. Pringsheimia scutata, mature frond with spores, after Reinke. 600 X i. 96. Chaetopeltis americana, portion of disk, after Snow. 400 X i. 97. Arthrochaete penetrans, after Rosenvinge. 500 X i. 98. Chaetobolus gibbus, after Rosenvinge. 300X1. 99. Diplochaete solitaria, by Lambert. 400 X i. 100. Endoderma Wittrockii, after Hazen. 400 X i. 101. Acrochaete repens, with sporangia, after Pringsheim. 500 X i. 460 TUFTS COLLEGE STUDIES, VOL. II, No. 3 PLATE XL 102. Ulvella lens, after Huber. 300 X i. 103. Gloeocystis gigas, after West. 500 X i. 104. Chaetosphaeridium Pringsheimii, after Klebahn. 800X1. 105. Urococcus Foslieanus, after Foslie. 800 X i. 106. Pleurococcus vulgaris, after West. 1000 X i. 107. Palmodictyon viride, after West. 406 X i. 108. Bolbocoleon piliferum, with sporangia, after Hauck. 600 X i. 109. Gloeotaeniuni Loitlesbergerianum, after Stockmayer. 500 X i. PLATE XII. no. Coleochaete divergens, with oogonia, after Pringsheim. 200 X i. iij. Tellatnia contorta, cross section, after Batters. 200 X i. 112. Tellamia contorta, surface view, after Batters. 300 X i. 113. Pithophora oedogonia, with akinetes, after Wittrock. 40 ; ' i. 114. Nylandera tentaculata, after Hariot. 300 X i. 115. Chaetomorpha aerea, basal and upper portions, after Hauck. 40 : i. 116. Herposteiron confervicola, after Hazen. 800 X i. 117. Trentepohlia Wainoi, after Hariot. 250 X i. 118. Dactylothece confluens, after Nageli. 1,000 X i. 119. Rhizoclonium hieroglyphicum, after Stockmayer. 300X1. PLATE XIII. 1 20. Pseudodictyon geniculatum, surface view, after Gardner. 500 X i. 121. Endophyton ramosum, section of host with endophyte, after Gardner. 300 X i. 122. Gloiococcus mucosus, after West. 400 X i. 123. Cephaleuros Mj'coidea, after Karsten. 200 X i. 124. Cladophora glomerata, after West. 100 X i. PLATE XIV. 125. Anadyomene stellata, after Oltmanns. 10 X i. 126. Spongomorpha spinescens, after Kjellman. 40 X i. 127. Cystodictyon pavonium, by Lambert. 10 X i. THE GREEN ALGAE OF NORTH AMERICA 461 128. Boodlea compacta, after Brand. 40 X i. 129. Cladophoropsis membranaceus, after Borgesen. 20 X i. 130. Halicystis ovalis, after Saunders. 2X1. PLATE XV. 131. Acetabularia crenulata, group of individuals, after Har- vey. 2X1. 132. Microdictyon Agardhianum, after Montague. 20 X i. 133. Hormiscia penicilliformis, filament, after Areschoug, 200 ; ' i. Zoospore, after Areschoug. 1000 X i. 134. Struvea anastomosans, after Harvey. 3 ) ' i. 135. Gomotia polyrhiza, with sporangium, after Bornet and Flahault. 300 X i. 136. Chamaedoris annulata, after Harvey, i X i. 137. Dictyosphaeria favulosa, group of individuals, after Har- vey. 10 X i. 138. Valonia utricularis, after Schmitz. 10X1. PLATE XVI. 139. Siphonocladus rigidus, after Howe. 20 X i. ,140. Chalmasia antillarum, stipe and disk, 5X1; details of base of disk, 20 and 40 X i, after Solms. 141. Sphaeroplea annulina, with oospores, after Hansgirg. 200 X i. 142. Dasycladus claveformis, after Hauck. i X i. 143. Neomeris annulata, group of individuals, after Cramer. i X i. 144. Codium tomentosum, iitricle and sporangium, after Thuret. 75 ; i. 145. Batophora Oerstedi, group of individuals, after Harvey. i X i. 146. Cymopolia barbata, after Harvey, i i. 147. Avrainvillea levis, after Howe, i X i. 148. Acicularia Schenckii, disk from above, 5X1; contents of sporangium, 10 X i, after Borgesen. PLATE XVII. 149. Penicillus capitatus, after Harvey, i i. 150. Rhipocephalus Phoenix, after Harvey. 2X1. 462 TUFTS COLLEGE STUDIES, VOL. II, No. 3 151. Cladocephalus luteo-fuscus, filaments of cortex, after Bor- gesen. 100 X i. 152. Derbesia marina, frond with sporangia, after Saunders. 40 X i ; zoospore, after Solier. 300 X i. 153. Vaucheria Gardneri, after Gardner. 100 X i. 154. Udotea cyathiformis, after Harvey, i X i. 155. Bryopsis plumosa, after Kiitzing. 20 X i. 156. Halimeda Opuntia, after Gobel. i X i. 157. Phyllosiphon Arisari, surface view, after Kiihn. 40 X i. PLATE XVIII. 158. Dichotomosiphon tuberosus, with oogonia and antheridia, after Ernst. 50 X i. 159. Ostreobium Quekettii, after Bornet and Flahault. 25OX i . 160. Caulerpa prolifera, after Reinke. i X i. TUFTS COLLEGE STUDIES, VOL. II, No. 3 PLATE I TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE II TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE III TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE IV TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE Y TUFTS COLLEGE STUDIES, VOL. II, No. 3. 49 • 5° PLATE VI 65 6 2 TUFTS COLLEGE STUDIES, VOL. II, No. 3. . PLATE VII TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE VIII TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE IX - , D^\°J€ xr TUFTS COLLEGE STUDIES, VOL. PLATE 96 • jw ^<^G)(\C^ m^p^®^h ,)0 r<_ ^^rr^trr-i^-^.^'l^b 4<9' A'A^Cc/rVC TUFTS COLLEGE STUDIES, VOL. II, No. 3. 102 PLATE XI TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE XII 116 TUFTS COLLEGE STUDIES, VOL. II, No. nnQno o »^»*» Q? ^f^XSP© 00© PLATE XIII 000 Q QOO w v ty <-_> /p ^XlJ^W^t) fr? Sg£&S*SSo^ 120 122 ^ TUFTS COLLEGE STUDIES, VOL. II, No. 3- PLATE XIV TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE XV TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE XVI TUFTS COLLEGE STUDIES, VOL. II, No. 3. PLATE XVII n'nv,M> '• if n ' 'Mi it1/', iCTiMj;-;1 '. a I'Mf/fl'l iM;lte«§M TUFTS COLLEGE STUDIES, VOL. II, No. 3- PLATE XVIII 464 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Botrydiurn, 97. granulatuni, 98, 154, Wallrothii, 98. 154. Botryococcus, 137. Braunii, 137, 138. Botryophora. Conquerantii, 383. occidentalis, 383. Branchipus. vernalis, 151. Brasenia, 88. Bryoideae, 410. Bryopsidaceae, 402. Bryopsis, 87, 402. corticulans, 404. Duchassaingii, 403. foliosa, 405. Harveyana, 405, 406. hypuoides, 402, 403. Leprieurii, 404 405. myura, 405. pennata, 405. • pennatula, 405. plutnosa, 402, 403, 404, 405, 406, 432. v. ranndosa, 404. v, seen n da, 405. ratnulosa, 404. simp/e.r, 407. Bulbochaete, 266. angulosa, 270. Brebissouii, 268. Can by 7, 271. crassiuscula, 271. crenulata, 269. dispar, 270. diu/iosa, 273. elachistandra, 270. gigantea, 271 iiisignis, 274. v. reticulata. 275. intermedia, 268. f. supramediaua, 269. minor, 275. mirabilis, 272. mouile, 272. nana, 272. Noidstedtii, 269. pol}-andria, 270. pygmaea, 273. rectangularis, 273, 274. v. hiloensis, 274. repanda, 274. rhadinospora, 274. setifera, 271. subsimplex, 273. varians, 274. v. subsimplex, 273. Calothrix, 152, 293, 294. parasitica, 284. pulvinata, 293. scopulorum, 152. Castagnea. virescens, 284. Caulerpa, 91, 409. ambigua, 421. Ashmeadi, 414. asplenioides, 414. c lav if era, 419. crassifolia, 413. f. laxior, 413, f. uiexicana, 413. f. pectiuata, 414. f. typica, 413. cupressoides, 416. v. disticba, 418. v. ericifolia, 417. v. Lycopodiuru, 417. f. alternifolia, 417. f. elegans, 418. f. intermedia, 418. f. plumarioides, 417. f. typica, 418. v. mammillosa, 417. f. nuda, 417. f. typica, 417. v. serrata, 417. v. Turned, 417. v. typica, 417. fastigiata, 411. v, confervoides, 412. Freycinetii, 415. v. de Boryaua, 416. f. occideutalis, 416. v. pectinata, 416. v. typica, 416. f. angusta, 416. f. lata, 416. lanuginosa, 415. Ivvcopodium 415 v. delicatula, 415. macrodisca, 421. tiie.ricana, 413. paspaloides. 418. v. laxa, 419 v. typica, 419. f. compressa, 419. f flabellata, 419. f. paspaloides, 419. f. phloeoides, 419. v. Wurdemanni, 419 f. phyllophlaston, 419. peltata, 421. v. typica, 421. f. imbricata, 421. pinnata, 413. THE GREEN ALGAE OP NORTH AMERICA 465 f. laxior, 413. f. pectinata, 414. phyllophlaston, 419. pliimaris, 414. f. brevipes, 415. f. Farlozvii, 415. /. lougipes, 415- • f. longiseta, 415. prolifera, 413. f. obovata, 413. f. zosterifolia, 413. pusilla, 412. racemosa, 419. v. clavifera, 420. f. niacropbysa, 420. v. gracilis, 421. v. laetevirens, 420. f. typica, 421. v. Lamourouxii, 421. v. occidentalis, 420. v. uvifera, 420. f. condensata, 420. sertularioides, 414. f. brevipes, 415. f. Farlowii, 415. f. longipes, 415. f. longiseta, 415. taxifolia, 414. verticillata, 412. f. charoides, 412. Webbiana, 412. f. disticha, 413. f. tomentella, 413. Caulerpaceae, 408. Cephaleuros, 320. Mycoidea, 321. Cerasterias, 166. raphidioides, 166. v. iuaequale, 166. v. incrassatum, 166. staurastroides, 166. Ceratophyllum, 147. Chaetobolus. 289, 290. gibbus, 289. Chaetoniorpha, 87, 181, 182, 288, 322, 326, 339, 350, 358. aerea, 324. antennina, 324. brachygona, 325. californica, 325. cannabina, 325. chelonum. 326. clavata, 323. v. torla. 323. intestinalis, 326. lanosa, 328. Linum, 325. longiarticulata, 325. Olneyi, 325. media, 326. melagonium, 290, 323. f. rupincola, 323. 324. f. typica, 323, 324. pacifica, 324. Picquotiana, 324. saccata, 326. sub marina, 328. sutoria, 325. tenuissima, 326. tortuosa, 328. Chaetopeltis, 288, 289. americana, 289. minor, 289. orbicularis, 289. Chaetophora, 295, 302. attenuata, 296. cornii-dainae, 297. elegans, 295, 296. endivaefolia, 297. incrassata, 296. maritima, 293. pellicula, 294. pisiformis, 296. Chaetophoraceae, 275. Chaetopteris. plumosa, 147. Chaetosphaeridium, 281, 311. globosum, 281. Pringsheimii, 281. Chalmasia, 380. antillana, 380. Chamaedoris, 371, 375. annulata, 375. Chara, 313. Characeae, 80. Characiopsis, 99, 149. acuta, 99. ellipsoidea, 100. minuta, 99. subulata, 100. Characium, 99, 149. acuminatum, 151. acutum, 99. ambiguuni, 150. cylindricum. 151. De Baryanum, 150. gracilipes, 151. heterornorphum, 150. minutum, 99. Naegelii, 150. obtusum, 150. Pringsheimii, 151. 466 TUFTS COLLEGE STUDIES, VOL. II, No. sessile, 149. Sieboldii, 150. strictuin, 150. subulatum, 100. Charoideae, 410. Chlamydomonadaceae, 128, 131. Chlamydomonas, 83, 128. angulosa, 129. communis, 129. globosa, 129. gracilis, 129. mucicola, 129. nivalis, 129. Reinhardi, 129. Steinii, 129. Chlorella, 157, 305. Chlorobotrys, 95. regularis, 95. Chlorochytrinru, 86, 146, 148. Archerianurn, 147. dermatocolax, 147. inclusum, 147. Knyanum, 147. Lemnae, 146. Schmitzii, 147. Chlorococcum, 143, 157, 305. endoziocurn, 144. huiiiicola, 143. infusionum, 143. iiatans, 144. Chlorocystis, 148. Cohnii, 148. Chlorodesmis. coruosa, 391. vancheriaeformis, 406. Chlorogonium, 130. euchlorum. 130. Chloromonadaceae, 92. Chlorophyceae, 91, 100. Chlorosphaera, 305. lacustris, 305. pannda, 305. Chlorotheciaceae, 99. Chlorotylium, 291. cataractaruin, 291. Chodatella, 160. citriformis, 160. Chorda. filum. 282. Chroolepus abiethiitin, 317. a tire inn, 316. I ol ilk us, 319. lagenifennn, 318. inoni/i forme, 320. odora/nm, 319. rigidulum, 320. umbrinum, 319, 320. Cladocephalus, 394, 396. luteo-iuscus, 397. scoparius, 396. Cladophora, 83, 86, 87, 288, 326, 327, 331, 357, 358, 362, 363, 366, 367, 376. aegagropila, 355. alaskana, 357, 358. albida, 336, 337, 340. v. refracta, 336, 344. amphibia, 349. anastomosans, 376. arcia, 359. v. centralis, 360. f. conglutinata, 359. /. debilis, 358. f. pnlvinata, 360. Bertolonii. v. hamosa, 344. brachyclados, 337. brachyclona, 341. callicoma, jjo, 352. canaliculans, 351. v. genuina, 352. cartilaginea, 346, 362. catenata, 347. catenifera, 347. Chamissoiiis, 360. coalita, 361. columbiana, 349. composita, 367. constricta, 339. crispata, 354. f. longissiina, 355. f. subsiuiplex, 355. v. virescens. f. thennalis, 354. f. vitrea. 354. crispula, 339. crucigera, 340. crystallina, 342. dalrnatica, 342. declinata, 351. v. jiiiitans, 351. delicatula, 337, 338. dijfnsa, 346. Engelmanni, 364. expansa, 198, 340, 343. v. glomerata, 341. fascicularis, 345. flavescens, 338. flexuosa, 336, 339, 342, 344. f. densa, 336, 340. f.floridana, 337. THE GREEN ALGAE OF NORTH AMERICA 467 fluitans, 352. fracta, 332, 339, 341, 353, 355. v. calcarea, 353. f. flavescens, 339. f. gossypina, 353. f. reflexa, 353. f. rigidula, 353. f. strepens, 353. v. subsitiiplex, 353. fuliginosa, 348. glaucescens, 199, 336, 340. glomerata, 332, 350, 351. v. callicoma. f. boreali-americana, 352. f. minnesotana, 353. v, clavata, 350. v.fasciculata, 350. v. macrogonya, 352. f. mucosa, 351. v. parvula, 351. f. rivularis, 351. gracilis, 337, 339, 340, 342. f. australis, 343. f. elongata, 343. f. expansa, 343. f. subflexuosa, 343. v. tennis, 343. v. vadoruni, 343. gratninea, 347. hamosa, 344. hirta, 340, 342, 343. holsatica, 355. Howei, 349. Hutchinsiae, 345. v. distans,346. hystrix, 358. insignis, 355. intertexta, 350. Kuetzingiana, 352. laetevirens, 340, 342, 345. lanosa, 357, 358. v. itncialis, 357. luteola, 338. macrogonya, 352. Magdalenae, 348. membranacea, 362. microcladioides, 344. Moi'fisiae, 356. nitida, 338. nifidissima. 342. oligoclona, 353. v. Flotowiana, 354. ovoidea, 346. pellucida, 347. polaris, 361. polyacantha, 337. prolifera, 347, 348. refracta, jj<5, 344, 351. repens, 349- Rudolphiana, 336. rupestris, 339, 346. saxatilis, 360. scitula, 341. scopaeformis, 361. secunda, 355. sericea, 342, Stimpsoni, 338. strepens, 353. trichocoma, 338. trichotoma, 349. trinitatis, 356. uberrima, 356. uncialis, 359. utriculosa, 346. vadoruin, 343. virgatula, 337. Cladophoraceae, 181, 321. Cladophoropsis, 362. membrauaceus, 362, 375. Classification, 89. Closterium. cuspidatum, 95. Coccocladus. occidentalism 383. v. laxus, 383. Codiaceae, 386. Codioideae, 386. Codiolum, 86, 87, 151. gregariutn, 152. f. intermedium, 152. intermedium, 152. longipes. 153. Petrocelidis, 152. pusillum, 153. f. americanum, 153. f. longipes, 153. f. typicum, 153. Codium, 386. adhaerens. 387. difforme, 387. elongatum, 388. isthmocladutn, 388. L/indenbergii, 388. mamillosum, 388. mucronatum, 389. v. californicum, 389. v. novae zelandiae, 389. repens, 388. Ritteri, 387. ten ue. v. repens, 388. tomentosum, 388. 468 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Coelastrum, 171, 305. cambricum, 173. microporum, 172. v. speciosum, 172. proboscideum, 172. reticulatuni, 173. sphaericurn, 172. Coleochaetaceae, 312. Coleochaete, 281, 312. divergens, 314. v. minor, 314. irregularis, 313. Nitellarum, 313. orbicularis, 314. pulvinata, 314, 315. scutata, 314. soluta, 313. Collinsiella, 141. tuberculata, 141. Conferva, 93, 95, iSr, 192. aerea, 324. amoena, 193. antillanun, 97, bornbycina, 96. f. minor, 96. f. tenuis, 96. brachyarthra, 324. cartilaginea, 361. centrifuga, 97. Chamissonis, 360. coalita, 361. collabens, 369. diffusa, 346. duriuscula, 358. fascicularis, 345. floccosa, 194. glomerata, 345. Li n ii in, 325. melagonium, 323. Mertensii, 360. minor, 97. pachydernia, 193. sax at His, 360. scitula, 341. serpcns, 97. sesquipedalis, 97. umbilicata, 366. utriculosa, 97. viminea, 360. Yonngana, 368. Confervaceae, 92. Confervales, 91, 92. Conjugales, 90, 91, 101. Conjugata, 107. longata, 118. Corniculatae, 422. Corona inferior, 378. Corona superior, 378. Craterosperinuvi ', 121. laetevirens, 125. Crucigenia, 170. apiculata, 170. crucifera, 170. rectangularis, 171. Cruoria, 147. Cyclops, 150. Cylindrocapsa, 222. amoena, 222. gemmella, 222. Cylindrocapsaceae, 222. Cymopolia, 382. barbata, 383. mexicana, 383. rosarium, 383. Cystococcus, 305. hunricola, 143. Cystodictyon. 366. pavonium, 366. Dactylococcus. De -Baryanus, 150. Dactylothece, 307. coufluens, 307. Dasycladaceae, 377. Dasycladus, 383. clavaeformis, 383. occidentalis, 384. Debarya, 119. glyptosperma, 120, 124. Derbesia, 406. Lamourouxii, 407. marina, 407. tenuissima, 406, 407. vaucheriaeformis, 406. Derbesiaceae, 406. Dermatophyton, 285. radians, 285. radicatis, 285. Desmidiaceae, 80, 101. Desmotrichuni. undulatum, 279. Dichotomosiphon, 394, 430. pusillus, 431. tuberosus, 431. Dictyocystis, 175. Hitchcockii, 175. Dictyosiphon, 284. Dictyosphaeria, 367. favulosa, 367. Dictyosphaerium, 173. Ehrenbergianurn, 174. Hitchcockii, 175. pulchellum, 174. THE GREEN ALGAE OF NORTH AMERICA 469 reniforme, 174. Dimorphococcus, 174. cordatus, 174. lunatus, 175.- Dioecious, 224. Diplochaete, 277. laiuellosa, 278. simplex, 278. solitaria, 278. Diplozyga, 107. Dissepiment inferior, 267. Dissepiment median, 267. Dissepiment superior, 267. Distribution, Si. Division horizontal, 225. Division vertical, 225. Draparnaldia, 300, 302. acuta, 303. glornerata, 303. platyzonata, 304. plumosa, 303. Dwarf males, 224. Ecballocystis. japonica, 141. pulvinata, 141. IVilleana, 141. Ectocarpus, 293. fasciculatus, 341. Ectosperma. clavata, 426. cruciata. 428. geiuinata, 427. sessilis, 428. Elachista. fucicola, 279. Elakatothrix, 167. atnericana, 167. Ellipsospora, 235, 247, 260, 272. Elodea, 147. Endoclonium, 284. Moebiusianum, 285.- Endoderma, 278. perforans, 279. Pithophorae, 280. polymorphuui, 280. viride, 279. Wittrockii, 279. Endophyton, 282, 283. ramosurn, 282. Endospore, 225. Enteromorpha, 148, 195, 208, 214, 341- acanthophora, 200. arctica. 203. aureola, 206. clathrata, 197, 199. compressa, 196, 201, 203. f. subsirnplex, 201. crinita, 196, 199. cruciata, 198. erecta, 200. fascia, 204. flexuosa, 203, 205. Hopkirkii, 198. intestinalis, 139, 203, 204, 205, 206, 210. f. clavata, 205. v. crispa, 205. f. cyliudracea, 205. f. maxima, 204, 205. f. tenuis, 205. linza, 206, 210, 216. f. crispata, 206. f. lanceolata, 206. marginata, 196, 202. micrococca, 204. f. bullosa, 204. f. subsalsa, 204. minima, 201, 204. f. glacialis, 201. f. rivularis, 201. percursa, 197, 198. plumosa, 198. polyclados, 202. prolifera, 199, 202. v. arctica, 203. v. trabeculata, 203. v. tubulosa, 203. ramulosa, 200. saliua, 202. v. polyclados, 202. torta, 198. tubulosa, 203. Entocladia. viridis, 279. Epicladia, 287. Flustrae, 280, 287. Epigynous, 224. Erernosphaera, 154. viridis, 154. v. major, 155. v. minor, 155. Eudorina, 133, 134. elegans, 134. stagnate, 134. Euglenopsis. subsalsa, 141. Euspirogyra, 107. Excentrosphaera, 155. viridis, 155. Exospore, 225. .Exsiccatae, 81. Exterior antheridium, 224. Filicoideae, 410. 470 TUFTS COLLEGE; STUDIES, VOL. II, Flagellates, 89, 92. Fucus, 185, 282. Fusola . viridis, 167. Gayella, 221. polyrhiza, 221. Gigartina. radula, 282. Globospora, 829, 243, 249, 262, 268. Gloeocapsa, 307. conJJ liens, 307. fcnestralis, 309. zostericola, 309. Gloeocystis, 143, 306, 307, 310. amp la, 309. chrysophthalma, 309. fenestralis, 309. gigas, 309. v. rufescens, 309. Paroliniana, 309. rupestris, 308. scopulorutu, 309. vesiculosa, 308. zostericola, 307, 309. Gloeothece. con flue us, 307. distans, 307. Gloeoti/a. caldaria, 183. Gloiococcus, 309. niucosus, 310. Gloiotaeniuin, 310. Loitlesbergerianuni, 310. Gomontia, 86, 370. Holdenii, 371. polyrhiza, 370, 408. Goraontiaceae, 370. Gonatonema, 12?. notabile, 127. ventricosum, 127. Gongrosira, 290. deBaryana, 290. Gonium, 131. pectorale, 132. sociale, 132. tctras, 132. Grayemnia. Menziesii, 365. Guignardia. alaskana, 220. Prasiolae, 220. Gynandrosporous, 224. Haematococcus, 130. Hookerianus, 306. ins ignis, 306. lacustris, 130. pluvialis, 130. Halicystis, 372. ovalis, 372, 373. Halimeda, 87, 397, 431. discoidea, 400, 401. favulosa, 401. gracilis, 399. incrassata, 399. f. monilis, 399. f. tripartite^, 399. /. typica, 398. lacrimosa, 399. Monile, 399. Optmtia, 399, 400. scabra, 400, 401. simulans, 401. tridens, 398, 402. f. tri partita, 399. f. typica, 398. Tuna, 400, 401. Halosphaeraceae, 154. Hansgirgia. flabelligera, 321. Herposteiraceae, 310. Herposteiron, 311. confervicola, 311. vermiculoides, 311. Heterokontae, 90, 91, 92. Hippuroideae, 410. Hormidium, 221. innrale, 221. parietinuni, 221. Horiniscia, 181, 182, 209, 367. collabens. 369. crassa, 369. flaccida. v. ca Id aria, 183. Hartzii, 369. iucrassata, 369. penicilliforuiis, 185, 368. Wormskjoldii, 368. Hortuospora, 187. mutabilis, 187. purpurea, 187. scalariformis, 188. Hormotila, 167. mucigena, 167. Hormotrich n in . boreale, 185. speciositm, 185, 368. Wormskjoldii, 368. Hyalotheca, 311. Hydra, 157. Hydria n n 1/1 . heteroinorphum, 150. Hydrocytiiun. acuminatuin, 151. Hydrodictyaceae, 175. THE GREEN ALGAE OF NORTH AMERICA 471 Hydrodictyon, 161, 175. reticulatum, 176. Hyella. caespitosa, 370. Hypogynous, 224. , Idioandrosporous, 224. Ilea, 206. fulvescens, 204, 206. Ineffigiata, 138. neglecta, 138. • Instructions for collecting, 85. Interior autheridium, 224. Iridaea, 148. laminarioides, 282, 287. Isokontae, 90. Keys, 83. Kirchneriella, 171. lunaris, 171. v. Diauae, 171. Laminaria, 282, 324. longicruris, 286. Sinclairii, 283. Lateral conjugation, 102. Laurencia. obtusa, 278. Leathesia. difformis, 284. L/eiosperma, 102. Letnna. gibba, 147. minor, 147. trisulca, 146, 147. Lithoderma, 290. Lithothamniou, 372. L,ittorina. palliata, 280. Lunatia. heros, 292. Lycopodioideae, 410. L/yngbya, 198. aestuarii. 341. confervoides, 432. Macrandria, 229, 235, 243, 247. Macrandrous, 224. Mastigocoleus. testarum, 370. Mesocarpaceae, 121. Mesocarpicae, 122. Mesocarpus, 121. crassus, 125. uiacrosporus, 125. nuinmiiloides, 123. parinilus, 123. pleurocarpus, 125. recurvus, 123. robust us, 124. scalaris, 123. Mesogloia. divaricata, 284. Mesospore, 102, 225. Micrasterias. falcatus, 157. Microchaete. • grisea, 293. Microcladia. boreal is, 345. Microcystis. Paroliniana, 309. Microdictyon, 283, 366, 367, 376. Agardbianum, 366. crassum, 366. umbilicatnin, 366. Microspora, 96, 192. amoeua, 185, 193, 330. f. crassior, 193. crassior, 185, 193. floccosa, 194. Loefgrenii, 193. pachyderma, 193. quadrata, 194. stagnorum, 193, 194. tumidula, 194. Willeana, 194. Wittrockii, 193. Microthamnion, 294. Kuetzingianum, 294. strictissinium, 295. v. ruacrocystis, 295. Monoecious, 224. Monostroma, 139, 207, 219. angicava, 210. arcticum, 210. v. intestiniforuie, 210. Blyttii, 213. crepidinum, 211. cylind race inn, 210. fuscuni, 207, 211, 213. f. Blyttii, 213. f. splendens, 213. Grevillei, 209, 210. v. intestinifonne, 210. v. lubricum, 209. v. Vahlii, 209, 210. groenlandicum, 196, 207, 208. Lactuca, 209, 210. latissimuni, 207, 211. leptodermum, 213. lubricnni, 209. orbiculaturu, 212. v. varium, 212. pulchrutn, 211. quaternarium, 212. 472 TUFTS COLLEGE STUDIES, VOL. II, No. 3 saccodeum, 210. splendens, 213. therinalis, 214. undulatuui, 211. v. Farlowii, 211. Vahlii, 209. Wittrockii, 211. zostericolnni, 213. Monozyga, 115. Mougeotia, 121, 122. calcarea, 127. capucina, 127. crassa, 125. delicatula, 124. divaricata, 124. elegantula, 126. genuflexa, 125. glyptosperma, 120. laetevirens, 125. levis, 124. niacrospora, 125. rnirmesotensis, 124. uumuiuloides, 123. parvula, 123. v. angusta, 123. quadrangulata, 126. quad rat a, 126. radicans, 123. recurva, 123. robusta, 124. scalaris, 123. sphaerocarpa, 123. tenuis, 126. v. minor, 126. verrucosa, 124. viridis, 126. Mycoidfa. parasitica, 321. Myxonenia. aestivale, 300. amoeiiinn, 299. attenuatnw, 301. flagelliferum, 299. glomeratum, 301. liibricum, 298. r. varians, 298. nanuin, 300. stagnatile , 301. stibsecn n dm 11, 301. subuligerum, 299. tenue, 300. therm ale, 300. ventricosum, 299. Mytilus. edulis, 144. Nannandres, 224. Nannandres uuicellulares, 262. Nannandria, 249. Nannandrous, 224. Nemalion. Andersonii, 284. multifidum, 284. Neomeris, 380. annulata, 382. Cokeri, 382. duinetosa, 381, 382. Keller i, 382. mucosa, 381. Nephrocytiuru, 160. Agardhianuui, 161. Naegelii, 161. Nitella, 313 Nomenclature, 84. Nylandera, 320. tentaculata, 320. Ochlochaete, 288, 289. ferox, 288. hystrix, 288. Oedocladiutu, 223. Oedogoniaceae, 83, 88, 222. Oedogoniurn, 91, 200, 223, 281 acrosporum, 259, 260. v. bathmidosporum, 260. f. boreale, 259. v. connectens, 259. v. florideuse, 260. Ahlstrandii, 247. apictilatuiu, 239. Areschougii, 263. f. robusturu, 263. arruigeruui, 251, 252. aster, 250. autumuale, 246. Borisianum, 255, 256, 257. Boscii, 237. f. dispar, 238. v. occidentale, 238. Braunii, 249. capillare, 234, 235. capilliforme, 234. v. australe, 234. f. DeBaryanum. 235. f. diversum, 235. f. validum, 234. cardiacum, 230, 231, 232. v. carbouicum, 231. cataractuni, 266. concateuatvim, 256, 257. v. seligcritin, 257. crassiusculuiii, 256. v. idioandrosporurn, 255. crass it i n, 240. f. ainplum, 241. crenulato-costatuua, 239. THE GREEN ALGAE OF NORTH AMERICA 473 v. aureufn, 239. f. cylindricum, 239. crispum, 244, 246. v. gracilescens, 245. f. typicum, 245. v. uruguayense, 245. cryptoporum, 229. v. vulgare, 229. cyathigerum, 260, 262. f. americanuin, 261. f. oruatum, 260. decipiens, 262. Donnellii, 252, 253. echinatuui, 251, 252. echinospertnum, 250. v. horridutn, 250. flavescens, 249. fonticola, 264. foveolatum, 233. fragile, 232, 233, 251. franklinianutii, 231. geniculatum, 234. gigaiiteum, 265. gracillinium, 247. grande, 241, 242, 243. v*. aequatoriale, 243. f. hortense, 243. v. angustum, 242. Howardii, 244. Huntii, 253. hystrix, 254. irregulare, 251. Landsboroughii, 241. Londinense, 266. longaturu, 258. Lundense, 258. macrandrium, 258. v. aemulans, 258. Magnusii, 230. margaritiferum, 238. martinicense, 240. mexicanum, 243. multisporum, 257. nobile, 248. nodulosum, 247, 248, 262. v. commune, 248. obesutn, 245. oboviforme, 241. obsoletum, 230. obtruncatum, 264. v. oblatum, 264. pachyandrium. 241. paludosutn, 237. v. americanum, 237. Pithophorae, 244. plagiostomutn, 233. v. gracilius, 233. platygynum, 264. plusiosporum, 230, 231. pluviale, 264. polymorphum, 232. pnnceps, 234. Pringsheimii, 246. v. Nordstedtii, 247. punctato-striatum, 243, 244. punctatutii, 240. pungens, 249, 251. pyriforme, 265, 266. Richterianum, 236. rivulare, 236. v. major, 241. Rothii, 262, 263. rufescens, 229. subsp. Lundellii, 229. sancti thomae, 265. scrobiculatum, 234, 240. sexangulare, 253. v. majus, 254. spirale, 253. stagnate, 235. stellatum, 252. suecicum, 230. taphrosporurn, 239. undulatum, 261. f. senegalense, 262. upsaliense, 235. varians, 232. Vaucherii, 232. vernale, 245. Wolleanum, 256. v. concinnum, 257. f. insigne, 257. Oocystis, 159. Borgei, 160. crassa, 160. lacustris, 160. solitaria, 160. f. major, 160. Oogonium erect, 267. Oogonium patent, 267. Operculata, 243, 247, 261, 262. Operculate, 225. Ophiocytiurn, 93. arbuscula, 95. capitatum, 94. circinatum. 94. cochleare, 94. cuspidatum, 95. gracilipes, 95. majus, 94. parvulum, 94. v. circinatum, 94. Ophrydiutn, 157. Ostreobium, 407, 408. 474 TUFTS COLLEGE STUDIES, VOL. II, No. 3 Quekettii, 408. Palmella, 136. rniniata, 137. v. aequalis, 137. Palmellococcus, 158, 305. marinus, 159. miniatus, 159. thermalis, 159. Palmodactylou, 140. simplex, 140. varium, 140. Palmodictyon, 310. viride, 310. Pandorina, 132. Morum, 132. Parthenospores, 105. Paspaloideae, 410. Pectinata, 102. Pediastrum, 161, 176. angulosuui, 176, 178. biradiatum, 179. v. emargitiatum. 179. Boryanum, 176, 177. v. granulatum, 178. v. undulatum, 178. duplex, 179. v. brachylobutn, 179. v. clathratum, 179. Ehrenbergii, 179. forcipatum, 176, 177. pertusum, 179. rot it la, 179. z>. emarginatum, 179. simplex, 177. v. duodenariuni, 177. v. Sturmii, 177. tetras, 179. tricornutum, 177. undulatum, 178. vagum, 176, 178. Pellucida, 376. Penicillus, 391, 396, 431. capitatus, 392, 393. dumetosus, 392. Latnourouxii, 392. v. gracilis, 393. Phoenix, 393. pyriformis, 393. Petrocelis,' 147. 152. Petrosipbon, 375. adhaerens, 375. Phycopeltis, 321 . Phyllactidium, 321. tropicum, 321. Phyllantoideae, 410. Phyllodictyon, 377. Pbyllosipbou, 407, 408. Arisari, 408. Pbyllosiphonaceae, 407. Pilinia, 86, 291 endophytica, 292. Lunatiae, 292. uiaritima, 293. minor, 292. Morsei, 293. Reinschii. 293. rimosa, 293. Piloboloideae, 422. Pitbophora, 362. aequalis, 363. v. floridensis, 363. affinis, 363. Cleveana, 244, 280, 364. kezvensis, 364. oedogonia, 363. v. I'aucherioides, 363. Roettleri, 364. varia, 364. Plagiospermioae, 122. Plagiospermum, 121. tenue, 126. Plates, 81. , Platyrlorina, 133. caudata, 134. Pleodorina, 132. californica, 133. illinoisensis, 133. Pleurocarpus, 125. columbianus, 125. mirabilis, 125. Pleurococcaceae. 217. Pleurococcus, 304, 305. aquaticus, 305. Kiitzingii, 305. mar in us, 159. regularise 305. vulgaris, 284, 304, 305. Polychaetophora, 278. lamellosa, 278. simplex, 278. Polyedrium, 161. angulosum, 164. armatum, 165. etwrine, 165. gigas, 165. gracile, 164. v. tenue, 164. irregulare, 164. minim inn, 163. minutnm, 166. inuttciun, 163. pachydermum, 164. punctnlatiitn, 163. quadratum, 164. « THE GREEN ALGAE OF NORTH AMERICA 475 quadricuspidatum, 164. recticulatutn, 163. tetraedricum, 165. v. longispinum, 165. tetragonuiH, 163. trigonum, 162. v. bifurcatum, 165. :'. pnnctatitin, 162. :r. tetragonum, 163. t u in id it I u vi , 165. f. rotundatum, 165. Polyhedra, 175. Polysiphonia, 200. Pontederia, 88. Pore inferior, 225. Pore median, 225^ Pore superior, 225. Porifera, 229, 235, 249, 260. Poriferous, 225. Porphyra, 219, 220. Prasiuocladus, 87, 141. lubricus, 141. subsalsus, 141. Prasiola, 218, 222. borealis, 220. calophylla. 219. crispa, 218, 220. subsp. marina, 222. fluviatilis, 220. Gardner i, 221. mexicana, 220. Satiteri, 220. tesselata, 220. Prasiolaceae, 217. Pringsheimia, 286, 287. scutata, 288. Protococcaceae, 142. Protococcales, 91, 100, 142. Protococcus, 142, 305. ovalis, 142, 305. viridis, 159. v. -iniiiiafiis, 159. Protoderrna, 211T. marinuru, 217. viride, 217. Protosiplion, 98, 153. botryoides, 99, 154. Prolosiphouaceae, 153. Pseudendocloaium, 86, 284. submarinum, 284. Pseudodictyon, 282. geniculatum, 283. Pseudo-Pleurococcus, 305. botryoides, 305. i' itl gar is, 305. Racemosae, 423. Radiofilum, 188. apiculaturn, 188. Ralfsia. Borneti, 284, 293. References, Si. Reinschiella, 95. cuspidata. 95. setigera, 158. Rhaphidiuni, 157. aciculare, 158. Braunii, 158. convolutum, 158. falcatuni, 157. v. aciculare, 158. v. fusiforiue, 158. fasciculatum, 158. fracturn, 158. minutuin, 171. polymorphum, 157. v, aciculare, 158. setigerum, 158. Rhipilia. longicaulis, 391. Rhipocephalus, 392, 393, 431. Phoenix, 393. f. brevifolius, 393. f. longifolius, 393. f. typicus, 393. Rhizocloniuui, 198, 326, 338, 353. antillarum, 329. Berggrenianum, 330. v. dominiceuse, 330. capillare, 325. Casparyi, 330. crassipellitum, 330. v. robustum, 330. crispum, 329, 330. erectum, 327. fluitans, 330. fontaiiutu, 330. fontinale, 330. hieroglyphicum, 329, 330. v, ainericaniiiii, 329. i'. atrobrunneum, 330. v. Hosfordii, 329. v. Kochianitin, 330. v. macrorneres, 329. Hookeri, 330. Hosfordii, 329. Kerneri, 329. Kochianum, 328, 329. lacitstre, 329. f. americamtm, 329. lanosuin, 328. inajits, 330. Occident ale, 330. pachydermum, 327. v. tenue, 327. 476 TUFTS COLLEGE STUDIES, VOL. II, No. 3 riparium, 327. v. irnplexuni, 328. v. polyrkizum, 328. v. validum, 328. stagnale, 330. stagnorum, 330. tortuosutn, 325, 328. f. polyrhizum, 328. Rhodochytrium, 148. Spilanthidis, 148. Salicornia, 350. Salmacis, 115. Sarcopbyllis, 148. Scalariforiu conjugation, 102. Scenedesinaceae, 155. Scenedesmus, 168. aciitus, 168. v. diinorphus, 169. antennatus, 169. v. rectus, 169. bijuga, 168. v. alternans, 168. v. flexuosus, 168. bijtigatus, 1 68. v. flexuosus, 168. candatus, 169. denticulatus, 169. diinorphus, 169. hystrix, 169. obliquus, 168. v. diinorphus, 169. polymorphus, 169. obtusus, 168. quadricauda, 169. f. abundans, 169. v. ellipticus, 169. f. horridus. 169. f. setosus, 169. f. typicus, 169. rotundatus, 169. Schizochlamys, 167. gelatinosa, 16f. Schizogoniutn, 187, 218, 222. crenulatum, 218. crisputn, 218. laetevirens, 186. murale, 218. v. alpinum, 218. Schizomeris, 189. Leibleinii, 189. Schizonema, 148. Sciadi inn, 94. arbuscula, 95. gracilipes, 95. Scrobiculata, 103. Scytosiphon. 284. Sedoideae, 41 1. Selenastrum, 171. Bibraianum, 171. ininutum, 171. Sessiles, 423. Siphonales, 91, 385. Siphonocladiales, 91, 321. Siphonocladus, 362, 371, 374. me mbr an ace us, 362, 371. rigidus, 374. tropicus, 374. Sirogonium, 119. ceylanicum, 119. stidicum, 119. Sorastrum, 173. bidentatuin, 173. spiuulosum, 173. Spartina, 185, 202. Spbacelaria. racemosa, 147. Sphaerella, 130. lacustris, 130. Sphaerocarpus, 123. scalaris, 123. Sphaerocystis, 310. Schroeteri, 310. Sphaeroplea, 384. annulica, 384. Braiinii, 385. crassisepta, 385. Sphaeropleaceae, 384. Spliaerosperiiiuin, 121. Spirogyra, 105, 200. adnata. 119. affinis, 113. bellis, 115. bifaria, 116. calospora. 118. f. gracilior, 118. f. major, 1 18. catenaeforruis, 108. cotnmums, 108, 109. coudensata, 109. v. Rusbvi, 110. crassa, 112. deciuiina, 110. v. subuiarina, 110. v. triplicata, 110. diluta, in. dubia, 115. v. lorigiarticulata, 115. e 'leg an s, 118. eloiigata, 119. flavescens, 113. fluviatilis, 114. fusco-atra, 109. gracilis, 114. Grevilk-ana, 117. THE GREEN ALGAE OF NORTH AMERICA 477 groenlandica, 11?. Hantzschii, 118. Hassallii, 117. inflata, 116. insignis, 117. v. elongata, 119. v. Hantzschii, 118. Juergensii, 108. jugalis, 111. longata, 107, 119. lutetiana, 114. majuscula, 112. v. brachymeres, 112. maxima, 112. v. inaequalis, 112. mirabilis, 113. neglecta, 114, 119. nitida, 110. orbicnlaris, 112. orthospira, 112. parvispora, 111. porticalis, 108. f. minor, 108. protecta, 118. pulchella, 116. punctata, 115. quadrata, 116. quinina, 108. rivularis, 119. setiformis, 111. Spreeiana, 116. stictica, 119. subaequa, 119. subsalsa, 110. tenuissima, 115, 119. ternata, 114. varians, 108. Weberi, 116. Spirorbis, 370. Spongilla, 157. Spongomorpha, 331, 332, 346, 356, 432- arcta, 209, 358, 359, 361. f. conglutinata, 359. v. penicilliformis, 359. f. pulvinata. 360. duriuscula, 357. hystrix, 358. f. debiiis, 358. f. littoralis. 358. f. typica, 358. lanosa, 358. v. uncialis, 359. rhizophora, 362. saxatilis, 360. v. Chamissonis, 360. spinescens, 360, 361. vernalis, 357. Spongopsis. saccata, 356. Staurogenia. cruciata, 170. Staurospermicae, 122. Staurospermum, 121. cap u tin um, 127. quadrat um, 126. viride, 126. Stephauokontae, 90. Stichococcus, 188, 189. bacillaris, 190. f. confervoideus, 190. flaccidus, 191. fluitans, 191. marinus, 190. rivularis, 191. scopulinus, 190. subtilis, 191. vStigeoclonium, 284, 285, 295, 297, 302. aestivale, 300. arnoenuin, 299. attenuatum, 301. flagelliferum, 299. glorneratum, 301. longipilus, 302. v. mill us, 302. lubricum, 298. v. varians, 298. minus, 302. nanum, 300. f. subsimplex, 300. stagnatile, 301, 302. subsecuuduui, 301. subuligerum, 299. tenue, 300. v. lubricum, 298. thermale, 300. ventricosum. 299. Streblouema, 284. Struvea, 367, 371, 375. auastotuosans, 376. v. caracasana, 376. deli cat n la, 376. pulcherrima, 376. ramosa, 377. Subepigyuous, 224. Subbypogynous, 224. Suffultory. 224. Tellamia, 280. contorta, 280. intricata, 281. Tenacula, 376. Tetraedron, 161. angulosum, 164. 478 TUFTS COLLEGE; STUDIES, VOL. II, No. 3 armatum, 165. v. minus, 165. bifurcatum, 165. enorme, 165. gigas, 165. gracile, 164. v. tenue, 164. minimum, 163. muticum, 163. f. majus, 163. f. punctulatuui, 163. pachyderruum, 164. f. leptodermuui, 165. f. minus, 165. puuctulatuui, 163. f. rectangulare, 163. quadratuni, 164. quadricuspidatum, 164. f. inaequale 164. regulare, 165. v. longispinum, 165. reticulatum, 163. tetragonum, 163. trigonum, 162. v. punctatum, 162. Tetranema. perciirsuni, 197. Tetraspora, 138, 167. bul lo set, 139. zr. cylindracea, 139. cylindrica, 138. v. extensa, 139. extcnsa, 139. gelatiuosa, 139. f. uuiformis, 140. lubrica, 139. v. lac mi os a, 139. inacrospora-, 140. Tetrasporaceae, 136., Thamniastruin, 166. cruciatum, 166. Thuyoideae, 410. Trentepohlia, 315, 320. abietina, 317. arborum, 318. aurea, 316, 317, 318. v. Pittierii, 317. v. poly car pa, 317. v. subsirnplex, 317. effusa, 318. lolitlius, 319. lagenifera. 318. odorata, 319. v. betulina, 320 v. umbrina, 319. ntficrii, 317. polycarpa. 317. rigidula, 320. setifera, 318. Tnckermanni, 317. it nibrina, 319. v. quercina, 319. iincinata, 316. villosa, 317. v. brachymeris, 317. Wainioi, 318. Trentepohliaceae, 315. Triboneina, 96. bombycinum, 96. f. tenue, 96. minus, 97. utriculosum, 97. Trichosolen, anfillant in , 403. Trochiscia, 144. aciculifera, 145. arguta, 146. aspera, 145. granulata, 145. hirta, 145. obtusa, 146. Reinschii, 145. recticularis, 145. sporoides, 145. Turnerella. Pennyi, 290. Tubuligerae, 422. Udotea, 394, 396, 430, 431. argeutea, 396. conglutinata, 395. cyathiforniis, 395. flabellata, 396. Flabellum, 394, 395. luteo-fusca, 397. minima, 394, 432. spinulosa, 395. tomentosa, 394. Udotoideae. 386. Ulothrix. 181, 222, 301, 309. aequalis, 184. caldaria, 183. collabens, 369. coitsociafa, 186. flacca, 185. flacdda, 188, 191. v. genitina, 188. implexa, 185. isogona, 368. laetevirens, 186. moniliformis. 184. oscillarina, 184. rivnlai'is. 19 r. scutata, 432. subflaccida, 186. THE GREEN ALGAE OF NORTH AMERICA 479 subtilis, 191. i'. tenerrima, 183. v. thermarmn, 183. v. variabilis, 183. tenerrima, 183. tenuissima, 183. variabilis, 183. v. marina, 190. zonata, 184, /pj. Ulotrichaceae, 180. Ulotrichales, 91, 180. Ulva, 86, 87, 196, 214, 219, 220. califoruica, 215. clathrata, 199. v. ramnlosa, 200. v. Rot/iiana. f. prostrata, 199. enteromorpha. v. intestinalis, 204. v. lanceolata, 206. fasciata, 210, 216. f. caespitosa. 216. f. expansa, 216. f. lobata, 216. f. taeniata, 216. gelatinosa, 139. Hopkirkii, 198. Lactuca, 209, 214, 216. v. Lactnca, 214. v. latissima, 215. v. mesenterifortnis, 215. v. rigida, 215. linza, 206. quatenaria, 212. thermalis, 214. Ulvaceae, 195. Ulvella, 285, 289, 290. americana, 289. confluens, 286. fucicola, 286. lens, 286. prostrata, 287. Urococcus, 306. Foslieanus, 306. v. ferrugineus, 307. Hookerianus, 306. insignis, 306. Uroueina, 188. confervicola, 188. Urospora. 309, 368. Hartzii, 369. crassa, 369. incrassata, 369. Worinskjoldii, 368. Utricularia, 88. Valonia, 362, 372 374. aegagropila, 373. confervoides, 373. ova I is, 372. ventricosa, 373. verticillata, 373, 374. utricularis, 373. Valoniaceae, 371. Vaucheria, 91, 350, 422, 432. aversa, 424. clavata, 425. coronata, 429. dichotoma, 425. Dillwynii, 423. Gardueri, 428. f. tenuis, 428. geminata, 427, 428. v. racernosa. 427. hamata, 426, 427. intermedia, 429. litorea, 430. longipes, 428. ornithocephala, 424. orthocarpa, 425, 426. pachyderina, 423. piloboloides, 429. v. compacta, 429. Pi I us, 425. polyspernia, 424. repens, 425, 426. sericea, 424. sessilis, 425, 426. sphaerospora, 429. terrestris, 426, 427. Thuretii, 424, 429, 430. tuberosa, 431. v. intermedia, 431. v. minor, 431. velutina, 430. Vaucheriaceae, 421. Vaucberioideae, 410. Volvocaceae, 131. Volvocales, 91, 127. Volvox, 135. aureus, 135. globator, 135. Xanthophyll, 91. Zoochlorella, 143, 156, 305. conductrix, 157. parasitica, 157. Zostera. . marina, 279, 288, 309. Zosteroideae, 410. Zygnema, 102, 311. anoinaluin, 103. v. crassum, 103. b if aria, 116. chalybeospermum, 104. cruciatum, 104. 480 TUFTS COLLEGE STUDIES, VOL. II, No. 3 cyanospermum, 104. Zygnemaceae, 88, 102. insigne, 104. Zygogoniuni, 120. leiospermum, 104. aequale, 121. pachydermurn, 103. Agardhii, 120. v. confervoides, 103. decussatuiti, 103. pectinatum, 103, 121. ericetorum, 120. v. anomalutn, 103. v. terrestre, 120. v. decussaturn, 103. parvulum, 121. f. terrestre, 103. pectinatum, 103. Ralfsii, 121. purpureum, 121. stellinum, 104.