1 ffi- SI i P- ; =0 ; m BY CHARLES S. BOYER, A.M., F.R.M.S. ILLUSTRATED WITH SEVEN HUN- DRED DRAWINGS BY THE AUTHOR PRESS OF J. B. LIPPINCOTT COMPANY EAST WASHINGTON SQUARE PHILADELPHIA 1916 .:... . THE DIATOMACE.E OF PHILADELPHIA AND VICINITY . COPYRIGHT, 1916, BY CHARLES S. BOYER PREFACE The present contribution to the local flora is intended as an introduction to more extended research. The study is of advantage in relation to the life history of aquatic animals, the deter- mination of ocean currents, as proved by polar discoveries, the investigation of geological strata where other fossil forms are absent, and the analysis of water supply; and, when we consider the universal distribution of diatomacese in the earth, the water and even in the air and the enormous deposits formed in past ages and still forming, we are able to realize the importance of a knowledge of these complicated forms and their function of purification. The absence of descriptive works of reference in available form in this country, the polyglot confusion of authorities abroad and the amount of time, patience and skill re- quired in obtaining, preparing and examining specimens, render the study one of difficulty. The bibliography is omitted, as it is understood by those who possess the works of reference, and but few synonyms are given, having but little, except historical, value, espe- cially when it is considered that modern investigators have no access to many of the earlier collections, when any of these exist. So far as the marine forms are concerned, it is probable that nearly all occurring north of Florida are here included, and the fresh-water species described represent a large proportion of those found east of the Alleghanies. All of the figures are drawn to the same scale, a magnification of eight hundred diameters, from specimens in my possession, nearly all of which were found in or near Philadelphia. If the work is of any value in inducing further investigation, I hope, in the words of Julien Deby, that "those who follow my advice will find in the study of these wonderful little organisms as much pleasure as I myself have found." THE AUTHOR. INTRODUCTION The Delaware River rises in the Western Catskill Mountains, flows southward for about three hundred and seventy-five miles, and expands into Delaware Bay about sixty miles from the sea. Its origin is among the Devonian and Carboniferous rocks, and in its course it passes through Silurian, Triassic and Cretaceous formations, finally reaching the Cambrian and Laurentian beds. It also drains regions of the glacial drift and beds which overlie over- turned Miocene strata, and are sometimes mixed with them. From the mountains, nearly four thousand feet high, to the Bay, where the depth of water is not greater than seventy- five feet, the diatomaceous flora, from Alpine cascades to the salt marshes of New Jersey, contains a larger number of species than any other equal portion of the American coast. The city of Philadelphia, about one hundred miles from the sea, lies at the junction of the Schuylkill with the Delaware, and much of the land near the rivers, especially south- ward, is flat and low, composed of recent alluvial deposits. In the central districts the ground is high, the deep sub-soil being mostly a dry gravel resting upon gneiss and schist, although it is in part composed of a bluish clay which was probably laid down in the bed of the ancient river before the last period of the glacial drift. The blue clay was not all de- posited at the same time, as in the lower strata many marine forms are found which do not occur in the upper layers. This is notably the case in a deposit obtained at Spreckel's Sugar Refinery and also at the east end of Walnut Street Bridge, where a layer of blue clay occurs which is overlain by glacial drift. In other parts of the city mixtures of blue clay with more recent deposits are found, including fresh-water forms from numerous creeks and rivulets which traversed what is now the city proper, and especially from the vicinity of Fourth and Market Streets, where there existed as late as the year 1700 a large pond known as the "Duck Pond" which was subject to tidal overflow from its outlet, Dock Creek. The river water at Philadelphia is not noticeably brackish, although the tide extends thirty miles above the city and, before the building of Fairmount Dam, to the Falls of the Schuylkill. At certain times, when the river is low, the influx of tide water is sufficient to produce an abundance of brack- ish water diatoms at Greenwich Point. The entire absence, however, at present, of many of the marine forms obtained in dredgings in the Delaware opposite the city, as at Smith's Island, now removed, and in certain well borings at Pavonia, Pensauken, Gloucester and other places in New Jersey, where the depth reached the old blue clay, indicates conditions quite different from those now prevalent. In the Bay itself comparatively few living species are found, at least in any abundance. In the study of local forms which follows, the district included may be considered as circumscribed by the circumference of a circle having a radius of one hundred miles from Philadelphia, containing the States of New Jersey and Delaware, the southeastern part of 5 6 INTRODUCTION Pennsylvania, a portion of Maryland on the south and extending eastward to New York Bay and Long Island Sound as far as New Rochelle. The greater number of fresh-water species described have been obtained from near the city along the Darby, Cram, Ridley and Brandywine Creeks and from various places in New Jersey, including the Pine Barren region of the southern part of the State. Numerous collections have been made in the Schuylkill and the various reservoirs and along the Wissa- hickon, "where an Alpine gorge in miniature of singular loveliness is to be found within the limits of a city." The fossil deposits are from well borings near Camden, N. J., and from excavations in various parts of the city. There appears to be no relation between the Miocene beds of the eastern coast and the deposits here described, all of which have been formed later than the glacial period or in an interval between two such periods. Apparently no diatoms grew during the glacial era, at least in sufficient abundance to leave any perceptible traces of their existence. An examination of glacial "flour" and clays from the Catskills shows an entire absence of these forms, and I have never found them in the milky flow from the glaciers of the Alps nor in the constantly muddy streams in certain of our Western States. The opacity of the water produces the same result as the absence of light in the deep lakes of New England, where diatoms are found only on the stalks or roots of water-plants near the shore, while in shallow ponds, such as the small lake near the summit of Mt. Lafayette, the growth is abundant. Certain species will grow wherever there are moisture, light and heat, but the greater number require the presence, in small amounts, of substances pro- duced by the decay of animal and vegetable life. An abundance of diatoms in fresh water is usually an indication of its potability, while their entire absence in shallow water may be due to an excess of bacteria. The specimens from which the drawings are made have been collected by the author for many years; in addition to possessing an almost complete library on the subject, he has had the advantage of examining material obtained by the late Mr. Lewis Woolman and numerous slides furnished by a number of friends, including Mr. John A. Shulze, Mr. Frank J. Keeley and Mr. T. Chalkley Palmer, to whom I here take pleasure in expressing my thanks. The difficulties of the study are well stated by Agardh in the following extract from the preface to his Systema Algarum: "Because, indeed, in this respect, no one will wonder whether in the distinction of spe- cies and reference to synonyms we have, perchance, committed many errors. They have occurred and are bound to occur, partly from the fact that one is not permitted to see the original specimens of all authors; partly, because sometimes even the original specimens of these plants are erroneous; partly, because the figures and descriptions of authors are often lacking and imperfect "There is added the difficulty of the study itself of these plants, their submerged habitat, the minuteness of their structure, the rarity of their fruit, the change in the dried INTRODUCTION 7 plant, the impossibility of culture, the fallacies of microscopical vision and the chaotic condition of Algology itself to-day." The words of Agardh, written in 1824, are almost as true to-day. The lack of authentic specimens, which we hope will be remedied in time by the collections of the Smithsonian Institute, numerous incorrectly labelled slides in amateur collections/ the imperfections of figures copied and recopied, without regard to relative size or correct references, and the confusion in the attempts to harmonize different descriptions, deter the student at the outset. The remaining difficulties mentioned by Agardh add, how- ever, to the remarkable interest these forms have always had, since no increase in optical perfection of the microscope serves to lessen the mystery of their structure and mode of growth. CLASSIFICATION The few species of diatoms first discovered were included by Lyngbye, Dillwyn, and others in the genus Conferva. In 1824, the species, increased to forty-eight, were separated by Agardh into eight genera distinguished partly by their mode of growth. But little change was made until Heiberg, in 1863, advocated the division into symmetrical and asymmetri- cal forms. Without entering upon a general review of the later classifications, including Pfitzer's and Petit's divisions according to the number and location of the chromatophores, or the arrangement of Prof. H. L. Smith, because of the presence or absence of a raphe, or that of Mereschkowsky into motile and immotile forms, the modification of all of these methods by Schuett is here adopted, varied in accordance with certain monographs which appear to offer advantage. It is customary, especially among writers who are familiar with other classes of plants, to decry any classification of diatoms according to the markings of their siliceous envelopes. As, however, one of the chief distinctions of the class is the possession of a more or less siliceous and indestructible frustule, and as the cell and its contents are never seen except within the valves, their variety forms the only available method of identification. The cell contents, owing to the difficulty of observing their living condition, their continued change, their lack of distinct variation and their entire absence in fossil forms, render their con- sideration as a complete method of classification an impossibility. If, however, the cell contents can be brought into relation with the markings of their siliceous envelope, it will be a consummation for which the future student of these complicated forms ought to be grateful. That this result is one to be expected may be inferred from the fact that the arrangement of protoplasmic masses in the interior of the cell is coincident in some cases with markings on the valve, and the character of the endochrome is assuming a certain value in accentuating the difference between such forms as Pkurosigma and Gyrosigma, or in the resemblance between Hantzschia and Nitzschia, or between Surirella and Campy- lodiscus. Mereschkowsky, however, states that it is necessary to be careful in "establish- ing the relationship between diatoms based on the resemblance of their chromatophores," 8 INTRODUCTION and further observes that in Hantzschia amphioxys, Scoliotropis lalestriata and Acknanthes brevipes, three widely separated forms, the chromatophores are essentially the same. In one of the earliest classifications of diatoms, the individual cell received less con- sideration than the nature of the filament or thallus in which many species occur in the first stages of their growth. Those, however, which exist in colonies at first are, sooner or later, broken up into separate frustules, either before or at the time of their maturity or previous to conjugation, while very many species are never seen except in a free state. The union of frustules, therefore, is of secondary importance and the group must be considered as filamentous or unicellular algse. Their relation to other algse is not well determined. Among the Desmidiacece, a family of the order Conjugates, of the class Chlorophycece, the cells are in many forms divided by a constriction into symmetrical halves. The Conjugales are starch forming, with walls of cellulose. In the Diatomacese the starch is replaced by oil globules, while the walls of cellulose are more or less filled with a deposit of silica. The Conjugales, however, reproduce by zygospores and usually contain pyrenoids, as may be seen in the parietal chromatophores of Spirogyra. In the class Heterokontce we have the reserve material in the form of oil, instead of starch, but there are no pyrenoids. To this class belongs the order Confervacece, in which the cells are unicellular or filamentous, and to which all of the Diatomaceae were referred. While, therefore, Diatomaceae have a close affinity to the Desmidiaceae and to the Confervacese, the determination of their origin, one from another, or from a common ancestral type, appears to be a matter of conjecture. MORPHOLOGY AND DEVELOPMENT THE CELL The cell membrane is composed of two usually equal parts, each of which consists of a valve and a girdle or zone formed of cellulose modified by silica deposited in an insoluble state from a very dilute aqueous solution. The valves are more siliceous and robust than the girdle. Both are in most species easily separable, or at least the bands of the girdle which may be more or less closely fastened to the valves have a motion over each other permitting the cell to en- large at pleasure. The longitudinal diameter of the cell, or the distance between the centres of the two valves, will vary according to the convexity of the valve and the age of the frustule which may be often determined by the width or number of the girdle bands. These, owing to their diversity of form and arrangement, will be further described under the generic diagnoses. The siliceous cell-wall is covered on the outside by a layer of protoplasm called the coleo- derm. This layer may be quite thin and evident only when treated with fuchsin or Bismarck brown, or it may be of considerable thickness. The cell contains the cytoplasma, protoplasm, cell-sap, endochrome, pyrenoids, oil globules and nucleus, together with certain other less understood bodies. The Cytoplasma is a thin skin of colorless plasma covering the entire inner surface of the cell. It is invisible in the living cell but is evident in plasmolysis. In long forms it is thickened at the ends and is condensed at the plasma bridge which frequently con- nects the two valves and divides the cell into two parts, each containing more or less pro- toplasm surrounding the vacuole in which are found the cell-sap and certain granules. In some forms, as Meloseira, the cytoplasma includes the entire mass of protoplasm. The Endochrome is seen in the form of one or more bands or plates, of a yellowish or brownish color, on the inner side of the valves or connective zone, or in granules or irregular masses, more or less numerous, on the inner walls, or sometimes grouped near the centre. It consists of a mixture of chlorophyll and diatomine which differ in their relative solubility in alcohol and in their spectroscopic analyses. The color varies from green to a chocolate brown in proportion to the amount of diatomine. So far as the func- tion of the endochrome is concerned it does not appear to differ from that of ordinary chlorophyll, absorbing, under the influence of light, the carbon, and disengaging the oxygen of the carbonic anhydride in the water. Diatoms do not live in absolutely pure or non- aerated water. The individual plates or granules of the endochrome are called chromato- phores. Their number and significance will be referred to in the description of genera. THE PYRENOIDS. — In the chromatophores of many species are found colorless, homo- geneous bodies, strongly refractive, of various shapes, usually lenticular or fusiform, which are known as Pyrenoids (Schmitz). They are scarcely evident in the living cell, but are distinguished by the action of hsematoxylin and other reagents. Flat forms occur in Surirella and Pleurosigma, lens forms in Pinnularia, Stauroneis, Synedra, Fragilaria and Nitzschia, while a spherical form is found in Cymbella cuspidata. The pyrenoids are always imbedded in the chromatophore. Their growth is by division. Schmitz con- siders them a part of the living chromatophore, and their substance as working material which in excess has become resolved into the nature of a crystal which its form sometimes re- sembles. Comparisons are made between them and crystalloids found in certain monocoty- ledons. The pyrenoid is evidently concerned in the formation of the chromatophore, or in its division. Much of the conjecture, however, is due to the behavior of pyrenoids in other plants. 9 10 THE DIATOMACE^E OF PHILADELPHIA AND VICINITY OIL GLOBULES. — It has been established by Pfitzer that starch and sugar, as assimila- tion products, are replaced by oil in the cells of diatoms ("da bekannlich Staerke und Zucker bei den Bacillariaceen nicht nachzuweisen sind ") . The oil drops are more or less numerous, of various sizes, and are found in the cytoplasma, the cell-sap, and sometimes the chroma- tophores. Mereschkowsky describes certain globules as elseoplasts, which he divides into four kinds according to their number and position. Whether all of these are oil globules is a question not yet determined. Other bodies, known as ' ' Buetschli granules, ' ' or volutin, and described as ' ' little blisters filled with a tolerably robust refractive substance," are considered by Lauterborn to be a nitrogen reserve store. They are found in the cytoplasma, or in the cell-sap, and can be fixed in picric acid and stained in methylene blue. NOTE. — For a discussion of the morphology of diatoms and a valuable re'sume' of the investigations of Buetschli, Karsten, Lauterborn, Mereschkowsky, Mueller, Pfitzer, Schuett, and others, the student is referred to "Der Bau der Diatomzelle," by Dr. Otto Heinzerling, in "Bibliotheca Botanica," 1908. CELL DIVISION The growth of diatoms follows the usual method of cell division as described by Sachs (Text Book of Botany, 2nd ed., p. 16): "The nucleus of a cell which is about to divide becomes broader, assuming the form of a biconcave lens, and its nucleolus breaks up into irregular granules which together with its other granular contents begin to form a nuclear disc in the equatorial plane. A delicate striation is now apparent in what is becoming the long axis of the nucleus, at right angles to the nuclear disc, and the characteristic nuclear spindle is gradually produced. The nuclear disc splits into two halves lying side by side, each of which travels to the corresponding pole of the nucleus; thus two nuclei are consti- tuted which are connected by fibrillse." The cell-wall and the chromatophore bands divide, each nucleus passes to the centre, and two new cells are formed. In the meantime, to permit of this division, the two sili- ceous valves separate, the girdle bands slipping over each other, and opposite the larger or enclosing valve a new valve is formed, the girdle band of which is seen later within the girdle of the mother valve. Opposite the smaller valve of the original cell and adjoining the new valve, another valve is formed which also produces a girdle within the girdle of the smaller valve. As a result of division we have, therefore, the valves of the original, or mother cell, the two new valves and four girdle bands. (PI. 40, Figs. 18 and 19.) In the process of division, the continual formation of new valves, enclosed in the older girdle bands, will naturally cause a reduction in the size of the frustule. While this reduc- tion, owing to the elasticity of the girdle, does not always occur, I believe, yet, in most cases, the diameter is so reduced that a rejuvenescence of growth is required. This is caused by the production of auxospores which may appear without conjugation. In this process, the beginning of which, in certain species, may be noticed by the increase in the size of the girdle as in reduplication, the two valves separate and within is formed a more or less spherical mass about twice the size of the original frustule and which forms on its circumference two large and often shapeless valves. These valves form others which assume the appearance of the original valves, but larger, and proceed to grow in the usual way. The reduction in size of the frustule seldom proceeds further than about half the size of the type form, so that, as a general rule, it may be stated that diatoms are not often smaller than half the larger size. REPRODUCTION The process of reproduction has been observed in many cases, but the conclusions reached are somewhat at variance with each other. The auxospore formation is simply a THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 11 method of rejuvenescence. When, however, the auxospores are thrown off from filamentous diatoms, it is probable that two may conjugate, their contents dividing each into two daugh- ter cells which unite into two zygospores. The usual method is the union of two frustules, which, throwing off the old valves, coalesce into a single mass of protoplasm which produces an auxospore, sometimes called a sporangial frustule. It is stated that in some cases two frustules coalesce and produce two auxospores. The existence of spores in diatoms is a much-disputed point. While they have never been seen, the inference that they exist is very great, as otherwise it becomes difficult to understand the sudden growth of species in localities and under conditions that seem to preclude the actual presence of the living frustule. It is a matter of common observation that, in examining collections of living forms, minute frustules or brownish globules appear to resemble larger diatoms. In gatherings of Gomphonema, when many specimens are sessile on the same object, numerous intermediate sizes, varying from minute globules to the type, are seen, yet not positively demonstrable as the same. Conjugation, the formation of auxospores, and the actual process of cell division are seldom seen, as they occur during the night or at least in darkness. It is advisable in order to observe reduplication to obtain the material about midnight and place it in very dilute alcohol. In filamentous forms, however, the cell division is easily observed at any time in its various stages. By immersing in picric acid (saturated solution), transferring to very dilute alcohol which is gradually increased in strength, and then passing through oil of cloves and finally to the mounting medium, excellent preparations can be made. By stain- ing with gold chloride alone the nucleus is made apparent without further treatment. EVOLUTION OF FORMS It may be assumed that diatoms originated in the sea; to deny this requires evidence of the existence of fresh-water species previous to the Miocene period which is entirely marine. In those subject to fluctuations of the waves, as pelagic diatoms, their existence appears to be contingent upon the methods by which the separate frustules can cohere. Various devices, including hooks, spiral bundles, horns and processes exuding threads of plasma, exist for holding together the frustules. When marine forms are found in quiet waters some of these devices, being no longer of any value, cease to grow, although free swimming diatoms are rare. They either occur in long chains or are stipitate or sessile. If it is further assumed that the fresh-water diatoms are found in greater abundance in later periods, the action of running streams makes necessary the provision of some means by which the species may continue to colonize. This may be recognized in the occurrence of linear forms chiefly in streams. Circular forms, such as Cyclotella which have no raphe, are found in quiet waters, such as pools or ditches, and never exist living in running streams. Those forms only would be able to live in water having a more or less swift current under one of three conditions: they must, as in Gomphonema, be adherent to surrounding objects by a stipe; or be enclosed in a gelatinous tube, as in Homceocladia; or have an independent motion powerful enough to overcome the influence of the current. It is true that many forms with a raphe have no apparent motion. In the case of Mastogloia provision is made in a gelat- inous cushion in which the frustules are preserved. In Cocconeis, with a true raphe in one valve only, in Epithemia, with a partial raphe, or in certain Eunotise with a trace of one, we find species evidently degenerate and parasitic. The long Synedrae, having only a median line, live in running streams, since they are attached at one end to other algae. Forms with a true raphe appear to be more highly developed, since they are able to seek locations favor- able to growth. Given, therefore, the structure of the valve, the habitat may be inferred. 12 THE DIATOMACEvE OF PHILADELPHIA AND VICINITY THE MOTION OF DIATOMS The erratic backward and forward movement of certain diatoms, especially those of the Naviculoid group, or the slow, rolling motion of Surirella, has been discussed in so many ways without definite conclusions that a brief statement will be sufficient. Osmosis, the amceboid movement of the coleoderm, the protrusion of protoplasm or protoplasmic threads through the raphe, the existence of actual organs of locomotion or cilia, and the lack of synchronism in the chemical action occurring at the ends of the cell which is sometimes divided by the plasma bridge, have been offered in explanation. The chief objection to the theory of cyclosis appears to be that the resultant motion is so greatly in excess of the rota- tion of protoplasm in the cell. More or less motion is observed in various kinds of free cells, but the movement of diatoms is not evident in those without either a raphe or a keel upon which and apparently by which the phenomena are produced. Mr. T. Chalkley Palmer, in various articles in the Proceedings of the Delaware County Institute of Science, especially in Vols. 1 and 3, gives the results of exhaustive experiments. "Nothing, it would seem," he says, " could be more conclusive as to the essential sameness of the nature of motion in monads and diatoms, than the fact that both monads and diatoms require oxygen in order to perform motion, that they come to rest when oxygen becomes scarce, and that they resume their motion when oxygen is again supplied." He also thinks "that the living substance of the cell, more or less deeply overlaid with coleoderm substance of varying consistency, and itself assuming that degree of fluidity which best meets the requirements of the situation, permeates the raphes, circulates in the keels, or in some cases protrudes quite beyond the silica, and functions as the actual pro- pulsive agent." THE FUNCTION OF DIATOMS Of all forms of vegetation, the Diatomaceae are, perhaps, the most ubiquitous. Where- ever a sufficient amount of moisture, heat and light are found, they grow. It was during the Miocene period that they first appeared, and, as marine forms, reached their greatest development, both as to size and beauty of marking, while their prevalence throughout the world in enormous quantities has been often mentioned. The Miocene beds of Richmond and Maryland continued over the Cretaceous formations of New Jersey have outcropped in certain localities within our district, but are not considered in this discussion. The function of diatoms is not essentially different from that of other algse in provid- ing food for aquatic animals, such as Salpae and oysters, but it is, however, in other respects that they are not only important but necessary factors in the preservation of life. "Full nature swarms with life; one wondrous mass Of animals, or atoms organized, Waiting the vital breath, when parent heaven Shall bid his spirit blow. The hoary fen, In putrid streams, emits the living cloud Of pestilence. Thro' subterranean cells Where searching sunbeams scarce can find a way, Earth animated heaves." I am not certain if Thomson fully understood the matter, but he has remarkably described the facts. When "the vital breath" of returning spring animates the earth, the "subterranean cells" of diatoms, the "atoms organized," through the liberation of vast quantities of oxygen, immediately begin the purification of the "putrid streams." Were these streams not so purified, the accumulation of animal and vegetable debris would event- ually cause an enormous bacterial growth fatal to animal life. DIATOMACE^E Unicellular or filamentous. Cells either free, sessile, united in filaments, immersed in a gelatinous envelope or in fronds composed of branching tubes; microscopic, enclosed in a more or less siliceous envelope (frustule), composed of two parts (valves), usually connected by an intervening band (zone or girdle). Cell contents include yellowish or brownish chloro- phyll-like bodies which occur in one or several bands (placcochromatic), or as variously dis- tributed granular masses (coccochromatic) lining the inner walls. Growth by ordinary cell division or by auxospores; sexual multiplication by the formation of sporangia. Valves of two kinds : (a) Those in which the markings or parts are more or less concentric (6) Those (Peimatae) in which the parts are more or less symmetrically divided By a line (pseudoraphe) o* by a cleft (raphe). CENTRIC.E Valves without a dividing line or cleft; markings more or less radiate; transverse section of frustule circular, polygonal, or elliptical, sometimes irregular. Divided into four groups: 1. Discoidtce. — Frustules (cells) discoid; valves without horns or elevations (sometimes with processes). 2. Soknoidece. — Frustules with numerous girdle bands. 3. Biddulphioidece. — Frustules box-like, i. e., with the longitudinal axis greater than in the Discoidese. Valves with two or more angles, elevations or horns. 4. Rutilarioidece. — Valves as if naviculoid, but with irregular or radial structure. Groups 2 and 4 are not included in our description. No. 2 contains plankton genera only, while No. 4 consists of genera not yet found in this locality. DISCOIDE.E 1. Costinodiscea. — Valve not divided by rays or costae into sectors; puncta sometimes radiate; ocelli or processes absent. 2. Actinodiscece. — Valve with radial striae divided into sectors ; ocelli and processes absent. 3. Eupodiscece. — Valve disc-shaped with mammiform processes or one or more ocelli. 1. COSCINODISCE.E (a) Meloseirince. — Frustules short, in chains. (b) Coscinodiscince. — Frustules disc form, usually single, rarely in short chains. (a) MELOSEIRIN.-E 1. Meloseira. — Valve punctate, with a constriction or furrow between edge of valve and girdle. 2. Gaillonella. — Valve punctate, with a circular collar or crest near edge of valve. 3. Lysigonium. — Valve punctate, neither keeled nor constricted. 4. Hyalodiscus. — Valve punctate in the centre; border with decussating radial lines. 5. Stephanopyxis. — Border of valve with a crown of thorns; valve areolate. 6. Pyxidicula. — Valve areolate, with a border of spines. 13 14 THE DIATOMACE^: OF PHILADELPHIA AND VICINITY MELOSEIRA AG. (1824), em. DE TONI (1892) (melos, a limb or member, and seira, a chain) Frustules globose, ellipsoidal or cylindrical, concatenate, closely joined together. Valve either simply punctate or punctate and areolate. A constriction of the cell-wall, forming a furrow between the edge of the valve and the girdle, is more or less evident. The genus Meloseira constituted by Agardh has been variously modified by Kuetzing, Thwaites, Wm. Smith, Van Heurck, De Toni, and others. In Systema Algarum Agardh included certain species of Conferva, of Lyngbye, Dillwyn and others, and limited his genus to frustules more or less globose (fila articulata ad genicula constricta), although in his Con- spectus Criticus (p. 64), he modifies the description (fila teretia articulata, articulis diametro aequalibus vel longioribus) to include M. varians. As, however, Lysigonium Link, Gaillon- ella Bory, and other genera enlarged by Ehrenberg and Kuetzing, came to be included under Meloseira, Thwaites- suggested the division of the genus into two: Orthosira, in which the frustules a,re not convex at the ends and Aulacosira in which no central line is apparent but with two distinct sulci. Wm. Smith adopts the genus Orthosira but rejects Aulacosira, including all forms under the former genus and Meloseira, suggesting that differences "exist in the formation of the sporangia" of the two genera. M. varians and M. crenulata appear to form auxospores or sporangial frustules in different ways, as will be noticed hereafter. As, however, the present state of our knowledge is so limited and as much confusion would result in further changing the nomenclature, I shall adopt, for the most part, the divi- sion made by De Toni, separating Gaillonella and Lysigonium and employing the name Melo- seira as emendated in Sylloge Algarum, although, as stated, it omits the species of Agardh. That a further division may be necessary is indicated by the differences existing between the Orthosira forms and the others. ANALYSIS OF SPECIES Frustules cylindrical and lengthened: Valves with two distinct furrows; granules small distans Valves with coarse granules granulata Valves denticulate on the margin crenulata Valves denticulate and constricted roeseana Valves with row of large puncta on the girdle side undulata Frustules cylindrical and compressed: Valves punctate and areolate sulcata The chromatophores consist of circular and compressed or irregular flat granules which lie along the wall of the cell. MELOSEIRA DISTANS (EHR.) KtJETZ. Frustules cylindrical, slender, with two furrows, one on each side of the suture; valve in zone view with fine puncta in longitudinal rows; puncta in valve view scattered. L. 7-10 ft. Meloseira nivalis Wm. Sm. Coscinodiscus minor Wm. Sm. Fresh water. Fossil in New England deposits. PL 1, Figs. 8 and 9. NOTE. — In all species of Meloseira, as well as Gaillonella and Lysigonium, the frustules are so closely coherent that when the filaments are broken entire frustules are less frequently found than a union of two valves of contiguous frustules. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 15 MELOSEIRA GRANULATA (EHR.) RALFS Frustules cylindrical, robust, 5-18 ft in diam., with large granules in longitudinal, some- times spiral, lines, variable in size and arrangement in the same filament. Valve in valve view with scattered puncta. Variable in relative width and length, passing to M. crenulata. Gaillonella granulata Ehr. Orlhosira punctata Wm. Sm. Fresh water. Fossil at Coldspring, L. I. PL 1, Fig. 10. MELOSEIRA CRENULATA (EHR.) KUETZ. Frustules cylindrical, with furrows on each side of the suture, 10-20 /j. in diam.; puncta in longitudinal rows. Margins of valves denticulate at the junction of the frustules; valves with puncta scattered at the centre, radiate at the circumference. Common in fresh water; quite variable in size. Gaillonella crenulata Ehr. Orthosira orichalcea Wm. Sm. in part; not Conferva orichalcea Mertens or Gaillonella aurichalcea Ehr. and Bailey. PL 1, Figs. 1 and 2. MELOSEIRA ROESEANA RAB. Frustules cylindrical, constricted toward each end, with coarse, longitudinal striae; valve convex, striae punctate, radiating, with several large granules at the centre. Connec- tive zone with longitudinal rows of fine puncta. Diam. 12-45 /*. Orlhosira spinosa Grev. Fresh water. Media, Pa. (Palmer ) ; not common. PL 1, Figs. 5 and 6. MELOSEIRA ROESEANA VAR. EPIDENDRON (EHR.) GRUN. Frustules denticulate at the margin; valve with coarse granules at the centre from which radiate lines of fine puncta. Wet rocks of the Wissahickon. PL 1, Figs. 3 and 4. MELOSEIRA UNDULATA (EHR.) KUETZ. Frustules single or in twos, usually broader than long, constricted near the margin. Valve with six to twelve internal projections forming with the outline of the constriction of the valve a polygonal figure within the circumference. Surface of the valve with radiat- ing lines of puncta disappearing toward the centre, at which are numerous coarse puncta. Meloseira gowenii A. Schmidt. Blue clay of Philadelphia, especially common at Twelfth and Market Sts. PL 1, Figs. 15, 16, 17. MELOSEIRA SULCATA KUETZ. Frustules quite robust, with diam. several times the length, deeply furrowed at the margin, areolate and punctate. Valve with radiating striae disappearing toward the centre, and with a double row of cells near the margin, the outer one having the appearance of a crown of teeth. Gaillonella sulcata Ehr. Paralia sulcata (Ehr.) Cleve. Paralia marina Heib. 2 16 THE DIATOMACE^ OF PHILADELPHIA AND VICINITY Marine and brackish. Common in all parts of the world, and fossil in the Miocene. The Philadelphia form is the var. genuina Grun. PI. 1, Figs. 11 and 12. In a gathering from Media of Meloseira crenulata (Palmer leg.), occasional filaments are noticed with much longer and narrower frustules which become enlarged in the middle and are seen to contain inner frustules in the process of still further division, as shown in Fig. 2, PI. 38. Meloseira dickei Thwaites shows internal box-like cells placed one within the other, which were supposed by Thwaites to be a method of reproduction. Wm. Smith doubts this, but is unable to offer any explanation. In the present form the mode of reduplication is that usually found in filamentous forms, but in this case the presence of perfect frustules enclosing others in the process of still further division has been heretofore unfamiliar to me. The swelling in the middle appears to indicate that not all filamentous diatoms are reduced in size by subdivision. In outline the valve is like that of a "truncated cone, " as described by Petit in referring to Gaillonella granulata var. bambusina Petit (Diat. Nouv. et Rares, Jour, de Micrographie, 1890). GAILLONELLA BORY DE ST. VINCENT (1823) (named after Gaillon, a botanist of Dieppe) Frustules ellipsoidal, united in long filaments, usually found in pairs; each valve is furnished with a circular collar or crest extending at right angles to the convex edge. Valve hyaline at the centre from near which radiate lines of fine puncta, 18-20 in 10 p. NOTE.— The original names of both Meloseira and Gaillonella are retained, as there is no good reason for contracting the Greek diphthong in the first, and the second is the correct spelling. GAILLONELLA NUMMULOIDES (DILLW.) BORY Frustules as in the generic diagnosis. Diam. 30 M- Conferva nummuloides Dillwyn (Brit. Confervae, p. 45, Sup. PI. B). Meloseira nummuloides Ag. Heiberg and O'Meara assign this species to Lysigonium moniliforme (Muell.) Link, which is not keeled. While Dillwyn's and Lyngbye's figures do not show the keel, it is probable from their descriptions that the angular outline produced by the keel was noticed. Marine or brackish. Coast of New Jersey; Hudson River (Bail.). PL 1, Figs. 13 and 14. Gaillonella moniliformis of Bailey is this form, as he describes it as having "two minute projections of the delicate transverse ridges seen near the ends of the two globules belong- ing to a joint. " (Amer. Jour. Science, 1842, p. 89, PI. 2, Fig. 3.) LYSIGONIUM LINK (1820) (luo, to loose, and gonu, a joint) Frustules globose, concatenate; valve simply punctate. LYSIGONIUM MONILIFORME (MUELL.) LINK Frustules usually in twos, not keeled; valve with puncta hi longitudinal lines, the puncta of the enveloping zone larger and in transverse rows. L. 25-40 M (De Toni). Conferva moniliformis Mueller (1783). THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 17 Conferva nummuloides Eng. Bot. pi., 2287, not Dillwyn. Meloseira barren Grev. Lysigonium nummuloides (Lyngb., Kuetz.) O'Meara=Gaillonella nummuloides (Dillw.) Bory. See O'Meara, p. 248. Marine and brackish. Long Island Sound and coast of New Jersey. PL 1, Fig. 7. LYSIGONIUM VARIANS (AG.) DE TONI Frustules cylindrical, in long filaments, slightly constricted on each side of the suture; puncta in oblique rows in zone view. Valves 15-35 M in diam. (De Toni), sub-plane, with fine puncta in lines radiating from the centre. Under medium magnification the frustules appear smooth. Very variable in size. Meloseira varians Ag. Fresh water. Common in ditches and springs. PL 1, Figs. 18 and 19. HYALODISCUS EHR. (1845) (hyalos, transparent, and discus, a disc) Frustules spheroidal; valve with a flattened, irregularly punctate umbilicus from which proceed radiating or decussating lines of fine puncta. ANALYSIS OF SPECIES Valves divided into sectors stelliger Valves not divided but interrupted by short dark lines at intervals .... radiatus Valves with very fine puncta scoticus HYALODISCUS STELLIGER BAIL. Valve with puncta in oblique decussating rows which, by reason of the difference in obliquity, form numerous sectors. Umbilicus irregular, with scattered, coarse puncta. Margin wide, striated. Podosira maculata Wm. Sm. Blue clay. Not common. PL 1, Fig. 22. HYALODISCUS RADIATUS VAR. ARCTICA GRUN. Valve with radiating puncta from a rather small umbilicus, the rays interspersed with short, dark lines, having the appearance of spines, at irregular intervals. Margin broad, striated. Pyxidicula radiata O'Meara. The Philadelphia form corresponds exactly to Grunow's variety which has closer puncta than the type form. Blue clay. Rather rare. PL 1, Fig. 21. 18 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY HYALODISCUS SCOTICUS (KUETZ.) GRUN. Valve small, with puncta about 24 in 10 /x, appearing hyaline. De Toni remarks that it resembles a small form of H. subtilis which occurs north and south of our limits and is yet likely to be recorded. Cyclotella scotica Kuetz. Podosira hormoides Wm. Sm. Blue clay. Not rare. PL 1, Fig. 20. Endochrome in the form of four flaps or patches bound together about a common pyrenoid. In H. subtilis numerous rod-shaped chromatophores lie in a row and are not bound in the centre (Mereschkowsky). STEPHANOPYXIS EHK. (1844) em. GRUN. (1884) (stephanos, a crown, and pyxis, a kind of vase or box) Frustules ellipsoidal, concatenate; valves tumid, of unequal convexity, coarsely areo- late, the cells in rows parallel to the longitudinal axis, not radiate, with stray spines or teeth placed concentrically more or less near the margin. According to Karsten the chromatophores are round or angular discs which lie near the connective zone. STEPHANOPYXIS TURRIS (GREV.) RALFS Valve cylindrical, with a crown of stout spines less than the diameter of the valve near the margin. Cells hexagonal, about 2 in 10 M, sometimes punctate. The valve hav- ing the greater convexity has the larger spines, though usually less of them. Creswellia turris Grev. (Gregory, Diat. of the Clyde, T. R. S. E., vol. 21, part 4, p. 66.) Stephanopyxis appendiculata Ehr.? Creswellia is incorrectly based, as stated by Ralfs, on the concatenation of the valves which was not noticed by Ehrenberg in the fossil forms. It had been suggested by Kuetz- ing in Systema Algarum (p. 126). Blue clay. Port Penn and Smith's Island. PL 2, Figs. 1 and 2. STEPHANOPYXIS CORONA (EHR.) GRUN. Valve larger than in turris, sub-globose, coarsely areolate cells, 4-5 in 10 M. One valve furnished with a crown of teeth shaped like the letter T and united at the top into a ring above the margin of the valve; the other valve with long spines more or less concentrically arranged. Blue clay. Not common. Fossil in the Nottingham deposit. PL 2, Fig. 3. NOTE.— The diatomaceous deposit, so often called "Bermuda" or "Bermuda tripoli, " especially by foreign writers, is in reality the Miocene stratum extending for miles along the Patuxent River near the village of Nottingham, Md. The author is perfectly familiar with the location, having made large collections there. The mistake in the name is due to the fact that Prof. Bailey received material from Mr. Tuomey marked "Bermuda Hun- dred," which is located near Petersburg, Va. Attempts have been made to find material there and while there is an earth containing Miocene diatoms at Petersburg, it does not exactly correspond to the material sent to Ehrenberg by Bailey, who was in doubt as to the locality. The Bermuda Islands are of coral formation and have no deposits of diatomaceous earth. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 19 PYXIDICULA EHB. (1833) (dim. of pyxis, a box) Frustules globular, solitary or in short fasciae. Valve more or less hemispherical, areolate, destitute of spines. PYXIDICULA CRUCIATA EHR. Valve hemispherical, with large, hexagonal cells. An inner stratum is finely punctate. Blue clay. Walnut St. Bridge. Rare. PL 38, Fig. 8. This form is not usually described as having punctate areolse, but it does not apparently differ from other forms of Pyxidicula of Ehrenberg as described by Kuetzing (Species Alga- rum, pp. 21-23), including P. areolata. In fact, it differs from Stephanopyxis, which is also sometimes punctate, only in the absence of spines. In fossil deposits the absence of an easily detached stratum is not significant. The difference, except in size, between it and P. mediterranea Grun. (V. H. S., PI. 95, Figs. 15 and 16), I am unable to determine. Although many species of Meloseira are fresh-water, the habitat of the group Melo- seirinse is, in general, marine. It more nearly coincides in structure and development with other algae not diatomaceous, the siliceous envelope constituting its most distinctive feat- ure. As we proceed in the classification, the structure both of the frustule and contents becomes more complicated. (6) COSCINODISCIN^E 1. Cyclotella. — Valve with two concentric divisions of different structure, one a wide border and the other a central surface. 2. Coscinodiscus. — Valve areolate or punctate, with a narrow border of the same structure. CYCLOTELLA KUETZ. (1833) (cycles, a circle) Frustules single or geminate, cylindrical, short, in zone view rectangular or with undu- lating sides. Valve usually with smooth or punctate striae, centre sometimes bullose, smooth, or with granules scattered or radiating. Chromatophores numerous along the valves (Pfitzer). CYCLOTELLA STRIATA (KUETZ.) GRUN. Valve 30-80 ju in diam., with coarse striae, 7-12 in 10 p, centre coarsely punctate and bullose. Coscinodiscus striatus Kuetz. Cyclotella dallasiana Wm. Sm. Common in the blue clay. PL 2, Fig. 9. CYCLOTELLA MENEGHINIANA KUETZ. Frustule in zone view rectangular, undulated; valve, 10-20 n in diam., marginal striae robust and transversely punctate, centre radiately punctate. Cyclotella kuetzingiana Wm. Sm. (not Thwaites). Crum Creek. PL 2, Fig. 8. 20 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY CYCLOTELLA MENEGHINIANA, VAR. STELLIGERA CL. AND GRUN. Differs from the type in the coarse radiating lines at the centre. Broomall Lake, Media. PI. 2, Fig. 4. CYCLOTELLA MENEGHINIANA, VAR. STELLULIFERA CL. AND GRUN. As in type but with the central rays granulate. Broomall Lake, Media. PL 2, Fig. 12. CYCLOTELLA STYLORUM (BR.?) V. H. Margin striated, the alternate striae thickened near the border, producing an appear- ance of subquadrate cells. Centre faintly granulate, the outer border of which is encircled by 10-12 puncta, each of which is surrounded by a small hyaline space. Blue clay. Rare. Van Heurck gives this form doubtfully as a variety of striata, while De Toni makes it synonymous with it. Van Heurck's figure is not that of Brightwell, but as the specimen above described is, I believe, exactly the same as Van Heurck's, I retain his name. PL 2, Fig. 10. CYCLOTELLA COMTA (EHR.) KTJETZ. Valve with marginal striae well marked, each third or fourth costa more robust than the others. Central part finely striated, the striae punctate, radiating. Fresh water. PL 2, Fig. 7. The form here figured is probably the variety radiosa Grun. and is from a New Eng- land specimen. It is quite likely to occur in this locality. CYCLOTELLA OPERCULATA (AG.) KUETZ. Frustules in zone view undulated. Angles rounded. Marginal costse alternating with minute spines; centre nearly smooth, depressed, convex or flexuose. Fresh water. PL 2, Figs. 5 and 6. The figure is drawn from a specimen from Boston, Mass., H. L. Smith Type Slide No. 107, marked equivalent to C. minutula Wm. Sm. CYCLOTELLA ANTIQUA WM. SM. Marginal costse alternating with thick puncta; centre finely granulate with subtrian- gular elevations. Frustules in zone view rectangular. Blue clay. PL 2, Fig. 11. The form corresponds to the original specimens of Wm. Smith in the deposit of Staven- ger, Norway. The genus Cyclotella comprises about seventy specific names, many of which may be referred to other genera, while some of Ehrenberg's are incapable of verification on account of the small size of the figures and the lack of sufficient description. About half of the forms are marine. The fresh-water species are usually found living in more or less stagnant water or in pools contaminated with drainage, being an exception to the general rule that diatoms are more abundant in water free from deleterious matter. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 21 COSCINODISCUS EHR. (1838) (coscinon, a sieve, and discus) Frustules solitary, cylindrical, compressed; valve circular or elliptical; surface flat or sometimes convex near the border; markings more or less angular, radiating, sometimes fasciculate; border usually well denned. Central space, if present, hyaline, sometimes sur- rounded with a rosette of large cells. Chromatophores round, angular or irregular discs usually without pyrenoids (Karsten). Rattray's classification is here followed, so far as it refers to our species. Excentrici. — Valves circular; central space absent; markings angular, in oblique, decus- sating rows. Lineati. — Central space absent; markings angular, oblique decussating rows straight. Fasdculati. — Markings fasciculate, or sometimes only near the border. Radiati. — Markings rounded or angular, more or less radiate. Elaborati. — Valves elliptical, markings rounded. EXCENTRICI COSCINODISCUS EXCENTRICUS EHR. Valve with a hyaline excentric space from which proceed, usually in six directions, rows of polygonal markings decreasing toward the narrow, coarsely striated border, the rows appearing convex toward the centre. Apiculi at unequal distances apart. Quite variable in size. Common in the blue clay and along the coast. PI. 2, Figs. 14 and 20. Fig. 20 is probably var. perpusilla Grun. (Diat. Fr. Jos. L., PI. 4 (D), Fig. 7). LINEATI COSCINODISCUS LINEATUS EHR. Valve circular, markings hexagonal, cells in parallel rows. Border narrow, cellular. Blue clay and Atlantic coast. Not common. PI. 3, Fig. 8. FASCICULATI COSCINODISCUS NITIDUS GREG. Valve flat, markings rounded, distant, radiate, decreasing toward the border which is coarsely striate. Quite variable in size and in the distance between the markings. Blue clay and Atlantic coast. Common. PI. 2, Fig. 18. COSCINODISCUS NITIDULUS GRUN. Valve usually not quite circular; markings smaller than in nitidus and fasciculate near the border. Blue clay. PI. 2, Fig. 19. Various intermediate forms between nitidus and nitidulus occur. COSCINODISCUS SUBTILIS EHR. Markings polygonal, irregular at the centre, but forming numerous fasciculi radiating 22 THE DIATOMAC&E OF PHILADELPHIA AND VICINITY toward the border, the rows parallel to the central row of each fasciculus. Border narrow with fine striae; apiculi often present between the fasciculi. Blue clay and along the coast. Very common in the water supply of Philadelphia and Camden, where the diameter seldom exceeds 40 M and the markings on the semi-radius are 10 in 10 M- PI. 2, Fig. 17. COSCINODISCUS DENARIUS SCHMIDT Markings larger than in C. subtilis, equal, forming usually ten fasciculi, each begin- ning near the semi-radius and containing ten parallel rows of granules. Common in the blue clay and sparingly along the coast. PL 2, Fig. 13. Forms are found intermediate between C. subtilis and C. denarius, as shown in Fig. 15. COSCINODISCUS POLYACANTHUS GRUN. Markings angular, 10 in 10 n, decreasing toward the border, fasciculate. Apiculi large, twelve or more, usually inserted at the middle of each fasciculus, and extending into the interior of the cell. The apiculi in outline resemble the heads of horse-shoe nails, and are seen with difficulty except when the valve is examined from the inner side. Border narrow, striated. Diam. 70 M- Pensauken, N. J., artesian well. PL 38, Fig. 5. Rattray's description of C. polyacanthus var. intermedia Grun., from Cape Wankarema, Siberia, gives the diam. as 60 /*, and there are about 7 markings by actual count in 10 n in Grunow's figure (Diat. Fr. Jos. Land, PL 3 (C), Fig. 25). The apiculi are more numerous, but there appears to be little doubt of the general similarity. The Philadelphia form is abundant in the Pensauken well deposit at a depth of 33 ft. The apiculi become quite dis- tinct in slides stained with silver nitrate by Mr. F. J. Keeley; they are distinct from small apiculi sometimes evident between the fasciculi. The specimens in the Pensauken deposit are mingled with other forms which cannot be distinguished from C. subtilis. Whether the two are identical, I am unable to determine. Rattray (Rev. Cos., p. 47) refers to H. L. Smith's Type Slide No. 100, from rice-field mud, Savannah, Ga., as C. subtilis. In Smith's slide, in my possession, a number of the forms show faint outlines of the large apiculi and are otherwise exactly like C. polyacanthus. RADIATI COSCINODISCUS VELATUS EHR. Markings angular, decreasing slightly toward the coarsely striated border, covered with fine puncta. Blue clay. PL 3, Fig. 2. COSCINODISCUS MARGINATUS EHR. Markings rounded, large, decreasing toward the broad border, which is coarsely marked with distant striae. The cells are punctate. Common in the blue clay. PL 3, Fig. 9. In the fossil forms the puncta are not evident, hence the species is usually described as not punctate. THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 23 COSCINODISCUS RADIATTJS EHR. Markings polygonal, slightly decreasing toward the border where they are much smaller; border well marked, striate. Quite variable in size. Common in the blue clay and along the coast. PI. 3, Fig. 11. Fig. 1 is probably a smaller form. COSCINODISCUS SUBATJLACODISCOIDALIS RATTR. Markings small, decreasing toward the border in somewhat fasciculate rows. About one-third the distance from the border are five (Rattray finds six) well-marked apiculi somewhat resembling those of Aulacodiscus. Border narrow, hyaline. Rare in the lower stratum of the blue clay. PL 3, Fig. 4. COSCINODISCUS ARGUS EHR. Markings angular with central dots, increasing from the centre toward the border, where they are smaller. Blue clay. PL 3, Fig. 7 (a small form). COSCINODISCUS BIANGULATUS SCHMIDT Central space and rosette absent, markings large, angular, not punctate, with large central papillae, decreasing toward the border. Border wide, coarsely marked with rows of granules, and with two indentations on the inner side distant from each other about two- thirds of the diameter. Blue clay. PL 3, Fig. 3. Distinguished from Coscinodiscus asteromphalus var. omphalantha Grun., which also has two constrictions, by the absence of punctate markings. COSCINODISCUS ASTEROMPHALUS EHR. Central space small, surrounded by a rosette of large polygonal cells from which radiate hexagonal cells, increasing about half way toward the border and then slightly decreasing. Cells punctate. Blue clay. PL 2, Fig. 16; PL 40, Fig. 12. COSCINODISCUS ASTEROMPHALUS VAR. OMPHALANTHA (EHR.) GRUN. Central space absent, rosette evident. Markings 2^ in 10 jit, somewhat smaller near the rosette and decreasing near the border, which is constricted in two places, as in C. biangulatus. Blue clay. PL 38, Fig. 10. COSCINODISCUS OCULUS-IRIDIS EHR. Central space and rosette distinct; markings polygonal, not punctate, with large papillae, smaller near the rosette, increasing toward the semi-radius, and then decreasing to the striated border which is comparatively narrow. Blue clay and Atlantic coast. PL 3, Fig. 10. 24 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY ELABORATI COSCINODISCUS LEWISIANUS GREV. Valves elliptical, major axis a little more than twice the minor. From a point, usually near one side, radiate rows of granules in lines nearly parallel to the major axis. Border broad, with distinct striae. Great Sedge Island, N. J. (artesian well), and in outcrops later than the Miocene, where it is usually found. PI. 3, Fig. 5. 2. ACTINODISCE^E ACTINOPTYCHINjE Valves divided into sectors alternately elevated and depressed. (1) Actinoptychus. — Sectors plane. (2) Polymyxus. — Sectors convex. ACTINOPTYCHUS EHR. (1839) em. V. H. (1890) (actis, a ray, and ptyx, a fold) Frustule cylindrical, less in length than the diameter, in zone view undulated. Valve divided into six or more sectors alternately raised and depressed, areolate and punctate, varying in the alternate divisions. The areolation is confined to the outer layer of the valve while the punctation is usually on an inner valve often found detached. Processes on the border, three or more. Umbilicus circular or angular, hyaline. ANALYSIS OF SPECIES Sectors, six undulatus Sectors, eight or more, cellular heliopelta Sectors, fourteen, punctate vulgaris ACTINOPTYCHUS UNDULATUS (KUETZ.) RALFS Valve areolate and punctate in quincunx, divided into six equal sectors, alternately elevated or depressed, their areolations appearing different. Margin well defined. Umbil- icus smooth, hexagonal. Processes three, sometimes six, inserted within the margin of each alternate division. Very variable in size and appearance. This is the Actinocyclus of Bailey, figured and described in Amer. Jour. Science, 1842, p. 93, PL 2, Fig. 11, but not named. Kuetzing describes and names it and refers to Bailey. Actinoptychus omphalopelta Ehr. Actinoptychus cettulosa Ehr., H. L. Smith Sp. Typ., 384. Quite common in marine and brackish water and in the blue clay. PL 4, Figs. 1, 2, 4 and 6. ACTINOPTYCHUS VULGARIS VAR. INTERRUPTA N. VAR. Valve with fourteen sectors, the alternate ones divided by a smooth lanceolate space for about one-half the radius, forming with the smooth, circular umbilicus a seven pointed star. The sectors thus divided have coarser puncta in quincunx than the other sectors, ending in a smooth area near the margin, and also larger black puncta scattered from the centre to the semi-radius. Near A. vulgaris var. neogradensis Pant. Blue clay. Not common. PL 4, Fig. 5. THE DIATOMACEJ3 OF PHILADELPHIA AND VICINITY 25 ACTINOPTYCHUS HELIOPELTA GRTJN. VAR.? Valve circular, sectors, eight, umbilicus circular, without rays ; border wide, cellular, with distinct rays. Inserted at a distance within the inner edge of the border are large processes, one on each of four alternate sectors, and two on each of the others. The sectors are cellulate and punctate. Near A. heliopelta var. versicolor Brun., which, however, in the specimen in my collec- tion from Atlantic City (artesian well), has a greater number of processes and they are situated on the edge of the border. Outcrop at Buckshutem, N. J. Rare. PI. 4, Fig. 3. It has been quite well determined, I think, that the typical forms of A. heliopelta occur at the base of the Miocene. At Rock Hall, Md., on the eastern shore of Chesapeake Bay, at a depth of from 21 to 130 ft., and at Wildwood, N. J., at a depth of from 78 to 179 ft., diatomaceous beds occur considered by Mr. Lewis Woolman (Geol. Surv. of N. J., 1898, pp. 116-121) "as synchronous in age," the former being deposited in the Delaware River Delta and the latter in the Chesapeake in post-miocene times. In each of these beds a small form of A. heliopelta is rarely found. The material at Buckshutem is post-miocene, and the form here figured shows a marked variation from the Miocene species and a gradual approach toward A. undulatus. POLYMYXUS L. W. BAIL. (1855) Valve circular, usually divided into fourteen sectors which are on the same plane at the centre, but the alternate ones are elevated into mammillated projections terminated by small processes on the margin. Zone view rectangular with undulations subconical, terminated by the processes. POLYMYXUS CORONALIS L. W. BAIL. Central space hyaline, rounded or slightly stellate, from which radiate rows of fine puncta in quincunx, shown in the figure only on the alternate elevations, the depressed interspaces being out of focus. The mammillae are stated by Bailey to vary from six to ten. Very rare in the blue clay (Walnut St. Bridge). Occurs also in the Wildwood deposit (Bull. Torrey Bot. Club, 1895, p. 261). PL 4, Fig. 7, and PL 5, Fig. 2. A^/A cef 3. EUPODISCEJE< ~~"*Aulacodiscinoe. — Valves with mammiform elevations near the border surmounted by nipple-like processes. AULACODISCUS— THE ONLY GENUS AS ABOVE ——Eupodistinoe. — Valves with ocelli. (1) Actinocyclus. — Valve with one small ocellus; striae radial. (2) Eupodiscus. — Valve with one or more ocelli; striae not radial. (3) Auliscus. — Valve with large, elevated ocelli. Central area hyaline. Markings granular and costate. (4) Pseudauliscus. — Valve with radiating granules. No central space. 26 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY AULACODISCUS EHK. (1844) em. RATTR. (1888) (aulax, a furrow, and discus) Valve usually circular, plane or with an elevated zone, frequently inflated beneath the processes; central space irregular or rounded, sometimes absent; markings granular, radial, sometimes in a reticulum. The genus comprises more than one hundred species most of which are fossil, and is represented in this locality by a single form, A. argus, included by Rattray in his section "Retiformes," distinguished by the presence of a reticulum. AULACODISCUS ARGUS (EHR.) SCHMIDT Frustule in zone view elliptical. Valve circular, 125-190 n in diam., closely covered with two kinds of markings, one, a mesh of large, radiating, angular cells, the outer plate, and the other, radiating rows of circular granules with hyaline spaces intervening and closer near the border, forming the inner plate which can occasionally be seen detached. Central space absent. The walls of the angular cells are crossed with fine lines and are probably composed of granules compressed so closely as to produce partial opacity, the depth of which depends in a measure not only on the superposition of the two plates, but on the relative closeness and thickness of the cell-walls. In a fully-developed specimen the effect is to produce more or less triangular cells containing three or four granules. In some cases the opacity is so great as to render detail invisible. In the figure the valve is supposed to be divided into three sectors, illustrating at "a" the lower plate> at "c" the combination of the upper and lower plates, and in the other sector the cellular mesh of the upper plate. Processes, usually three, quite robust and in- serted at from one-fourth to one-fifth the length of the radius from the border which is striated on the inner side. A form with four processes is found in the lower blue clay. Tripodiscus argus Ehr. Eupodiscus argus (Ehr.) Wm. Sm. Not uncommon in the blue clay. PI. 4, Fig. 8. ACTINOCYCLUS EHR. (1837) (actis, a ray, and cycles) Valve circular or elliptical; surface flat at the centre, sloping toward the border. Cen- tral space usually evident, rounded or irregular. Markings rounded, granular, punctiform, in radial, or nearly radial, rows, sometimes fasciculate. A nodule, more or less evident, is found near the border which is usually striate. Chromatophores round discs or granules. ANALYSIS OF SPECIES Valve circular, rows radial, hyaline lines at the border barkleyi Valve circular, rows fasciculate moniliformis Valve elliptical ellipticus The nodule is generally supposed to be a thickening of the cell-wall, and, in the opin- ion of Rattray, a projection outward, but "whether there may not be at the same time a slight inward protuberance is difficult to determine," though, as a rule, he seems to "think there is not." THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 27 ACTINOCYCLUS BARKLEYI VAR. AGGREGATA RATTR. Surface flat from centre to semi-radius. Central space irregular, sometimes with a few scattered granules. Markings round with central dots distinct, about 7 at the centre, de- creasing in straight radial rows to 12 in 10 n at the border, where they form moniliform striae. Border narrow with striae about 16 in 10 ju. Hyaline interspaces at the origin of the shorter rows, but not at equal intervals. At the border, linear hyaline spaces occur at somewhat irregular intervals between the moniliform striae owing to the termination of certain radial rows before they reach the circumference. Nodule small, from one-seventh to one-fourth the radius from the border. According to Rattray the distinction between A. ralfsii and A. barkleyi is partly in the absence of the zone arrangement of the hyaline spaces in the latter, and to the slight dif- ferences in the number of granules. The variety aggregata differs from the type form of barkleyi mainly in the distance of the nodule from the border. I have specimens from the blue clay material at Walnut St. Bridge, and from Smith's Island, in which the distance from the border in one case is, as stated above, quite different from that in the other. In specimens from Morris Cove, Conn., the locality referred to by Rattray, variations occur. Blue clay. PL 6, Fig. 1. In the figure the subulate hyaline spaces at the border are, in some instances, wider than usual. ACTINOCYCLUS MONILIFORMIS RALFS Surface flat, from centre to about five-sixths of the radius. Central space rounded, with one or more granules. Markings, 8 in 10 n, round, in radial rows, fasciculate, the oblique transverse rows irregular, very slightly decreasing until near the edge of the flattened zone, and then suddenly decreasing and appearing as decussating lines oblique to the border. Apiculi distinct, interfasciculate within the border. Nodule quite evident, surrounded by a rather wide irregular hyaline space on the margin of the flattened zone in the middle of the fasciculus. Border wide, with striae about 20 in 10 /*. Blue clay. Port Penn. Not common. PI. 6, Fig. 2. Equivalent to Actinocyclus ehrenbergii, H. L. S. Type Slide 10. In a valve from Port Penn, Delaware Bay, two nodules occur nearly opposite each other. ACTINOCYCLUS ELLIPTICUS VAR. DELAWARENSIS N. VAR. Valve rhombic-elliptical. Markings somewhat angular, 6 in 10 ju at the centre where they are sub-concentric, thence decreasing in lines radiating more or less toward the bor- der, where they suddenly become punctiform, striae about 20 in 10 n. Border equal to one- fifth the radius. A nodule is found on the inner side of the border. Apiculi apparently absent. The markings are larger than in the Richmond forms which are associated by Rattray with Actinocyclus ellipticus Grun. The form corresponds closely to Witt's Cestodiscus ovalis var.? (Witt, Polirschief. von Archangelsk-Kurojedowo, PI. 8, Fig. 2), except as to the border. It does not answer to Van Heurck's figure or any other. Blue clay. Very rare. PI. 3, Fig. 6. 28 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY EUPODISCUS EHK. (1844) (eu, well, pous, a foot, and discus) Valve circular, 45-117 M in diam. (De Toni). Central space absent, surface plane with angular cells. At the border short, circular processes or ocelli. EUPODISCUS RADIATUS BAIL. Valve with radiating hexagonal cells, sometimes slightly curved toward the large ocelli inserted near the border which are hyaline at the centre. Border wide, coarsely striate. The number of ocelli heretofore recorded is four. Specimens with five processes are found in the artesian well at St. Augustine, Fla., and in material at Twelfth and Brandy- wine Sts. Mr. Hugo Bilgram has discovered valves with three and six ocelli. Not common in the blue clay, but abundant along the southern coast of the Atlantic states and the Gulf of Mexico. Not Eupodiscus radiatus Wm. Sm, which is Biddulphia smithii (Ralfs) V. H. PL 5, Fig. 3. AULISCUS EHR. (1843) (aulax, a furrow, referring to the grooves in certain species, according to De Toni, but preferably from auliscos, a small reed, referring to the processes?) Frustule cylindrical; zone with longitudinal rows of fine puncta. Valve circular or elliptical, plane except near the processes; central area hyaline, usually circular. Markings of two kinds, granules radiating or scattered and radiating, costate lines, prominent or indistinct. Processes, two or three, large, short, cylindrical, with hyaline surface, near the ends of the major axis in a line oblique to it. Auliscus is divided by Rattray into fourteen sections, defined chiefly by the character and arrangement of the markings. About eighty species are described, but as many of the forms are fossil, occuring in the Miocene of California, Oamaru and elsewhere, and as so few species are found in this locality, I shall refer but briefly to this division. Striolati. — No transverse median areas, striae inconspicuous punctatus Lineolati. — Markings distinct, pruinose, interrupted pruinosus Costati. — Transverse median areas usually distinct, markings continuous, costate J sculptus 1 cselatus AULISCUS PUNCTATUS BAIL. Valve broadly elliptical, or suborbicular, covered with delicate interrupted strise radiat- ing in sinuous lines to the circumference, more evident on the transverse median area; puncta 3 in 10 n, grouped into a rounded area on each side of the median line, elsewhere scattered. Central space rounded, processes two, large, suborbicular. Port Penn, Delaware River. Rare. PL 5, Fig. 6. AULISCUS PRUINOSUS BAIL. Valve elliptical, with distinct, interrupted, pruinose, irregular markings diverging in curved lines toward the circumference in the median part and converging toward the proc- esses, interspersed with numerous darker markings having the appearance of apiculi. Cen- tral space nearly circular, sometimes with several granules. Processes large near the ends of the major axis and not oblique to it, or scarcely so, the edges with a crenulate border. Blue clay. Rather rare. PL 5, Fig. 8. THE DIATOMACELE OF PHILADELPHIA AND VICINITY 29 AULISCUS SCULPTUS (WM. SM.) RALFS Valve elliptical or subcircular, median areas distinct, rounded, circumscribed by coarse distant costse radiating near the border where they are more evident, and converging to- ward the processes. Central space rounded, sometimes indefinite. Processes, two, circular. Typical specimens show wide, coarse, distant costse, but, in some cases, the median areas are indistinctly outlined. Blue clay. PI. 5, Fig. 5. AULISCUS CvELATUS BAIL. Valve elliptical or subcircular, with radiating costse, more evident around the median areas and at the border, converging toward the processes, with intermediate punctate radiating lines. Central space rounded or irregular. Processes circular. A. sculptus has coarser costse and the interspaces are hyaline, or apparently so, while in A. cselatus the punctate strise between the costse are more evident. Blue clay. Not uncommon. PL 5, Fig. 4. Fig. 7 is a small, indefinite form intermediate between A. sculptus and A. cselatus. The numerous variations in this genus make it difficult to satisfactorily differentiate the species. The size of the four above described varies from 40 to 150 n- PSEUD AULISCUS A. S. (1875) AND LEUDUGER-FORTMOREL (1879) Valve circular or subcircular, nearly flat or depressed at the centre. Central space not evident. Processes circular, with narrow border, near the circumference. Border narrow, striated. Markings granular, radiating, sometimes interspersed with strise and apiculi. Differs from Auliscus chiefly in the absence of a central space and costse. PSEUDAULISCUS RADIATUS (BAIL.) RATTR. Valve circular, or nearly so, flat. Central area with scattered granules radiating and increasing in size outward in diverging rows toward the border which is coarsely striated. Processes, two, circular. Two small apiculi are inserted at about one-fifth the radius from the border near the ends of the minor axis. Blue clay. Rare. PL 5, Fig. 9. The apiculi are not always figured. They appear in a number of specimens from the Miocene of Maryland, Atlantic City, Harvey Cedars and Newbern. PSEUDAULISCUS SPINOSUS (CHRISTIAN) RATTR. Valve subcircular or slightly quadrangular, depressed at the centre and rising to an elevated zone near the border, the two zones separated by a distinct line. The inner zone indistinctly reticulate with fine puncta radiating from the centre and apiculi at intervals. The outer zone with smaller apiculi surrounding the inner zone and with intermingled rows of fine puncta and interrupted diverging strise. Near each end of the minor axis is a rather long, robust spine inserted at one-fourth the radius from the border which is narrow and striated. Processes circular, close to the circumference. Auliscus spinosus Christian. Blue clay. Rare. PL 5, Fig. 10. The genus is named by Schmidt, described by Leuduger-Fortmorel and emendated by Rattray. 30 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY BIDDULPHIOIDE.E BIDDULPHIE^E (a) Triceratiince. — Frustule cylindrical or prismatic, with three or more sides. (b) Biddulphiince. — Frustule cylindroid; valve with ends elevated into round proc- esses or long horns. (c) Anaukce. — Valve elliptical, lunate or triangular, with internal septa. (d) Euodiece. — Frustule cuneate in zone view; valve lunate. (a) TRICERATIINCE (1) Ditylum. — Frustule imperfectly siliceous. Zone with numerous divisions. Valve with central spine. (2) Trinacria. — Processes with sharp spines. DITYLUM BAIL. (1861) (dis, two, and tyle, a swelling, referring to the outline of the frustule) Frustule quadrangular, convex at the ends. Valve triangular, with undulating sides, the angles ending in a sharp point surmounted by a bristle. Surface of valve convex at centre from which projects a long stout spine. DITYLUM INTRICATUM (WEST) GRUN. Valve with the angles separated from the central part by lines imitating septa. Sur- face with radiating lines of fine puncta. Blue clay. Rare. PL 6, Fig. 4. Detached valves only have been found in the blue clay. The form is regarded as but slightly siliceous and, therefore, the zone or girdle not being found in the fossil deposits, I am unable to illustrate it from material in the vicinity. On Plate 38, Figs. 6 and 7, I have sketched the zone and valve views of specimens found recently at Vera Cruz and labelled by H. L. Smith Triceratum intricatum West. I can find no difference between the recent and fossil forms of the valves. The zone is covered with fine puncta in quincunx, not visible under ordinary illumination. The form as figured in Plate 6 corresponds to the figure of Lithodesmium undulatum Ehr. in Van Heurck, and West, in describing the Triceratium undulatum Wm. Sm. (figured as T. striolatum), thought that his T. intricatum was distinct from Ehrenberg's form on the ground that the latter came from the "Bermuda" (Nottingham) earth and must be strongly siliceous. Lithodesmium is characterized by the envelopment of the frustules by a cellular membrane which does not appear, evidently, in Ditylum. D. brightwellii is distin- guished by its crown of spines on the margin; otherwise it closely resembles D. intricatum. TRINACRIA HEIB. (1863) (treis, three, and acra, a point) Valve triangular, angles elevated into spines. Cells at the margin large. TRINACRIA PILEOLUS (EHH.) GRUN. Valve with concave sides. Surface concave with unequal punctiform and scattered markings with central dots. Cells at the margin large, rounded. At the angles, which vary in elevation, a few puncta are seen. Triceratium pileolus Ehr. Blue clay. Rare. PI. 6, Fig. 9. THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 31 (6) BIDDULPHIIN^E BIDDULPHIA GRAY (1831) em. VAN HEURCK (1885) (a genus, constituted from Conferva biddulphiana of the English Botany, named after a Miss Biddulph) Frustule prismatic or subcylindrical, concatenate, filamentous, or in zig-zag, or, as usually found, free. Zone well developed. Valve triangular, polygonal, elliptic or subcir- cular, convex, more or less elevated at the angles into processes or horns. Markings cellu- lar or punctate. Chromatophores, small plates of various forms. KEY TO THE SPECIES Valves costate biddulphiana Valves not costate: Markings cellular, angles elevated into horns favus angles not elevated antediluviana Markings punctate, angles with subconical processes and long spines granulata spines short rhombus spines minute smithii processes truncate, valve elliptical turgida valve orbicular laevis processes absent, valve divided by irregular lines alternans not so divided reticulum BIDDULPHIA BIDDULPHIANA (SMITH) Frustule quadrangular with convex ends and rounded angles. Valve elliptical with undulated sides, divided by septa into three or more sections. Processes large, rounded, globular or subconical. Zone varying in width. Surface with rounded reticulations hi lon- gitudinal and transverse rows, except at the centre where they are concentric and smaller. Conferva biddulphiana Smith (English Botany, 1807, PL 1762, upper figures). Diatoma biddulphianum Ag. Biddulphia pulchella Gray. Blue clay. Hoboken Tunnel. Along the coast. PL 7, Figs. 1, 2, 3, and 4. Quite variable in size and number of septate divisions. Fig. 3 is an unusual form with narrow zone, having but one row of large reticulations, evidently a young frustule. BIDDULPHIA FAVUS (EHR.) V. H. Frustule quadrangular, elevated at the angles into subconical processes oblique to the longitudinal axis. Valve triangular or quadrangular, plane, of two layers, the outer layer composed of large hexagonal cells in rows parallel to the sides, the inner of small puncta radiating from the centre. Zone punctate in quincunx, never found open. Triceratium favus Ehr. Blue clay. Common along the coast. The quadrangular form occurs only southward. PL 6, Fig. 6. At "a" a cell showing the lower punctate layer. PL 40, Fig. 16, a trans- verse section of a portion of the valve showing the cellular structure and the punctated lower stratum. 3 32 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY BIDDULPHIA ANTEDILUVIANA (EHR.) V. H. Frustules quadrangular, sometimes united in zig-zag chains. Valve quadrangular with more or less concave sides, sometimes cruciform. Surface with angular cells arranged in concentric and radiating lines increasing toward the circumference. At each angle is a large, rounded process, which, as well as the secondary layer, scarcely visible, is finely punctate. Amphitetras antediluviana Ehr. Amphitetras tessellata Shad. Blue clay. Rare. PI. 6, Fig. 3. A cruciform variety occurs at Pensauken, N. J., artesian well (Coll. F. J. Keeley). BIDDULPHIA GRANULATA ROPER Valve elliptical-lanceolate, convex, with diagonal rows of puncta 12 in 10 n and some- times with small scattered spurs. Processes inflated at the base, obtuse at the ends, which are curved outward toward alternate sides. Near each process and on opposite sides of the longitudinal axis is placed a stout spine bent or curved inward near the middle. Connec- tive zone with diagonal rows of puncta smaller than those on the valve. Pavonia, N. J., artesian well. Fossil in the Pleistocene. Along the coast. Not com- mon. PI. 7, Fig. 6. BIDDULPHIA RHOMBUS (EHR.) WM. SM. Valve rhomboidal, sometimes triangular, with subconical processes. Surface convex with hexagonal reticulations, 7-9 in 10 M, irregular at the centre and radiating to the circum- ference. Minute spurs are scattered over the surface, and on each side are usually two or three short spines. Common along the coast and fossil in the Miocene and later deposits. PI. 7, Fig. 5 (somewhat inclined, as usually seen). BIDDULPHIA SMITHII (RALFS) V. H. Valve orbicular, convex, with reticulations 5 in 10 p. radiating from the centre and decreasing toward the margin and processes which are truncate. A short spine is found on each side half way between the processes. Zone narrow with fine puncta 12 in 10 M in lon- gitudinal rows. Cerataulus smithii Ralfs. Eupodiscus radiatus Wm. Sm. Blue clay. Along the coast southward. PL 7, Fig. 8. BIDDULPHIA TURGIDA (EHR.) WM. SM. Valve elliptical or orbicular, surface convex. Processes very large, cylindrical, placed obliquely and inclined by the torsion of the frustule. Between the processes are two stout spines, one on each side, frequently forked at the ends. Puncta fine, irregular at the centre and radiating toward the circumference. Cerataulus turgidus Ehr. Blue clay. Along the coast. Quite variable in size. PI. 7, Fig. 7. THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 33 BIDDXJLPHIA L^EVIS EHR. Valve suborbicular or triangular, with short, truncate processes. Surface with fine puncta about 13 in 10 n radiating in straight or curved lines toward the circumference and with fine spurs at intervals. Nearer one process than the other, and about half way between centre and circumference, are two small spines, one on each side. Quite variable hi size. Blue clay. Common along the coast. PL 7, Fig. 9. Fig. 10 (magnification about 260 diameters only) illustrates sporangial frustules dis- covered by Mr. T. Chalkley Palmer at Reedy Island, Delaware River. In frustules having a cylindrical form, the endochrome lines the cell-walls in the form of granules which become congregated toward the centre in the sporangia. BIDDULPHIA ALTERNANS (BAIL.) V. H. Valve triangular or, rarely, quadrangular, with sides straight or slightly concave, usually unequal. Angles obtuse, separated from the centre by costate lines. Surface with puncta of irregular shape, large at the centre, with smaller puncta interspersed. In many valves several lines appearing like costae extend inward from the border in various direc- tions. Angles with small puncta in transverse and longitudinal rows. Triceratium alternans Bail. Blue clay. Along the coast. PI. 6, Fig. 7 and probably Fig. 8. BIDDULPHIA RETICULUM (EHR.) Frustule quadrangular. Valve triangular with straight or concave sides and rounded angles. Surface convex at the centre and angles. Markings of unequal size, mostly larger at the centre, scattered; at the angles, small puncta in longitudinal rows. Triceratium sculptum Shad. Triceratium punctatum Br. Triceratium obtusum Br. For explanation of the synonymy see "Biddulphoid Forms of N. A. Diat.," Proc. Acad. Nat. Sci., 1900, p. 724. Blue clay. Along the coast. PI. 6, Fig. 5. (c) ANAULE^E EUNOTOGRAMMA WEISSE (1854) (eu, well, noton, a back, and gramma) Frustule quadrangular. Valve elliptical or lunate divided by septa which constrict the margin. Surface flat with punctate markings. EUNOTOGRAMMA UEVE GRUN. Valve lunate with obtuse ends. Septa, from four to eleven or more. Surface with puncta in transverse and longitudinal rows, sometimes indistinct and scattered. Shark River. Rare. More common southward. Fossil at Buckshutem, N. J. PI. 7, Fig. 11, and PI. 10, Fig. 15. I am unable to distinguish between E. laeve and E. debile, as intermediate forms occur. 34 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY TERPSINOE EHR. (terpsinoos, gladdening?) Frustules quadrangular, adnate in filaments, usually free. Valve elliptical or triangu- lar, with undulating sides divided by septa into three or more sections. TERPSINOE AMERICANA (BAIL.) RALFS Valve lobed at each end or angle. Central space rounded, hyaline. Surface with fine puncta in radiating lines. Blue clay. Not common. PI. 6, Fig. 10. TERPSINOE NOV^E-CvESARE^] BOYER Valve triangular, with concave sides and broad angles equally three-lobed, separated from the central part by septa. Central space small or absent. Puncta delicate, radiating or scattered. L. of side 62 n. Pleistocene clay at Buckshutem, N. J. Fossil at Wildwood, N. J. T. americana, forma trigona Pant.? (Le Diatomiste, Vol. 2, p. 207.) PI. 6, Fig. 11. (, in trans- verse and longitudinal rows. Along the coast. Common. PL 17, Fig. 20. MASTOGLOIA APICULATA WM. SM. Valve elliptical-lanceolate, sometimes with slightly produced apices; median line between two ribs; central space very small; loculi numerous; puncta in slightly radiating rows and in longitudinal lines. Along the coast. PL 17, Figs. 21, 22, 23. MASTOGLOIA ANGULATA LEWIS Valve elliptical, with produced apices; loculi usually less than 12, unequal, the larger in the middle; striae, 12 in 10 M, puncta in decussating rows. "Differs from apiculata in its more broadly elliptical shape, the smaller number of its loculi and the angular character of its striation" (Lewis). 88 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY Considered by Cleve as synonymous with M. apiculata Grun., not Wm. Smith, and by De Toni as synonymous with M. apiculata Wm. Sm. In any case, M. angulata Lewis is not the same as M. apiculata Wm. Sm., the loculi of which are equal. Atlantic City. H. L. Smith T. S. No. 211. PI. 17, Fig. 17. STAURONEIS EHR. (1843) (stauros, a cross, and neis (naus), a boat) Frustules free, sometimes geminate; valve as in Navicula but with a stauros. Cell contents as in Navicula. Mereschkowsky, however, says that the chromatophores always contain more pyrenoids than are found in Navicula. Heinzerling gives the number as two to four in each chromatophore. Cleve includes under Naviculse Microstigmaticse all species of Stauroneis, Pleuro- stauron, Schizostauron, certain Schizonemse and Naviculse. As a matter of convenience, and because I have already included certain Schizonemse and Scoliopleura under Navicula, and because of the small number of species in our locality, I have arranged them under the three divisions of Cleve as follows : Stauroneis. — Forms having a true stauros, without diaphragms. Pleurostauron. — Forms like Stauroneis but with diaphragms at the ends. Schizostauron. — Forms having a bifid stauros. STAURONEIS PHCENICENTERON EHR. Valve lanceolate, obtuse; strise radiate, 18 in 10 n, distinctly punctate. L. usually 125 M but sometimes 200 M- Common in fresh water. PI. 27, Fig. 1. STAURONEIS ANCEPS EHR. Valve lanceolate, with rostrate or capitate ends; stauros in some cases does not reach the margin. The varieties are very numerous. Var. gracilis (Ehr.) Cl. — Valve lanceolate, strise very fine; margin of stauros striated. L. 100 M. Cape May, N. J. PI. 27, Fig. 5. Var. amphicephala (Kuetz.) Cl. — Valve capitate at the ends; strise, 24 in 10 ju. L. 47 ft. Fresh water. PI. 27, Fig. 7. Var. ? — Valve with produced ends; strise, 30 or more in 10 //• L- 104 ju. Willistown, Pa. PL 27, Fig. 4. Var. ? — Valve with produced ends; strise, about 28 in 10 p., punctate. L. 47 n. New- town Square. PI. 27, Fig. 8. Var. ? — Valve with produced ends; strise, 22 in 10 n, showing a tendency to form longitudinal rows of puncta as in Stauroneis stodderi Greenleaf, but the rows are not so evident. L. 60 p.. Pavonia, N. J., artesian well. PL 27, Fig. 9. STAURONEIS FRICKEI VAR. ANGUSTA N. VAR. Valve lanceolate, gradually tapering to the obtuse ends; terminal fissures prominent, forking at a distance of 7 p, from the ends. Frustules frequently geminate. L. 173 ju. Newtown Square. Rare. PL 26, Fig. 18. Near Stauroneis frickei A. S. (Atlas, PL 242, Fig. 16), except that the stauros is narrow at the margin. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 89 STAURONEIS SALINA WM. SM. Valve lanceolate, obtuse; stauros narrow, with short, scattered striae at the margin, 18 in 10 n, punctate. L. 65 /*. Along the coast. Common. PI. 27, Fig. 6. STATJRONEIS LEGTJMEN EHR. Valve elliptical-lanceolate, inflated in the middle, with produced sub-capitate or ros- trate ends separated by diaphragms. Stauros wide, striated at the margins; axial area very narrow; striae radiate, about 26 (?) in 10 /*, punctate. L. 28 ju. Pavonia, N. J., artesian well. PI. 39, Fig. 15. In Cleve's description and Van Heurck's figure, the median inflation is "not larger than the others." In the present form the median inflation is wider. STAURONEIS ACUTA WM. SM. Valve rhombic-lanceolate, obtuse; a diaphragm at each end; stauros widened outwards; striae, 15 or 16 in 10 ^, punctate. L. 130 /u. Blue clay. PI. 27, Fig. 2. STAURONEIS AMERICANA A. S. Valve elliptical-lanceolate, obtuse; striae, 14 in 10 p. L. 119 /*. Pavonia, N. J., artesian well. Rare. The only specimen found is asymmetrical with respect to the transverse axis. On Plate 40, Fig. 4, is illustrated an abnormal form of Stauroneis, apparently near S. acuta, having an elongated central nodule and radiating, curved and coarsely punctate striae. Blue clay. STAURONEIS SMITHII GRUN. Valve lanceolate, inflated in the middle and at the ends, which have diaphragms and are produced into rostrate apices; stauros reaching the margin; striae parallel, about 25 in 10 n (28 to 30, Cleve), distinctly punctate. Not uncommon in meadow pools near Newtown Square. PI. 27, Fig. 11. STAURONEIS CRUCICULA (GRUN.) CL. Valve lanceolate, with obtuse, produced ends; stauros bifid; striae, 24 in 10 n, oblique, parallel to the branches of the stauros, closer at the ends, punctate. L. 32 p. Newtown Square. East Park Reservoir. Rare. PI. 27, Fig. 10. NAVICULA BORY (1826) (dim. of navis, a boat) Valve linear to elliptical; ends acute, rounded, rostrate, capitate or truncate; axial area usually distinct; central area distinct, rounded or rarely extended into a transverse fascia; striae transverse or radiate, punctate; central area not dilated into a transverse stauros nor into horns. 90 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY The endochrome in the greater number of species consists of two chromatophores extending along the zone and sometimes partly over the valves. Sometimes, however, as in N. hennedyi, N. lyra and N. humerosa, the bands are on the valves. Certain species have four bands, others eight, and in one the endochrome is granular. (Mereschkowsky, 1. c., p. 9 et seq.) Pyrenoids are usually absent. On account of the diversity of the chro- matophores, Mereschkowsky considers the genus not homogeneous. The difficulty of arranging groups according to the cell contents, however, is so great that, for the present, the species must be described by the usual characteristics of the valves and divided as follows, according to Cleve, to the extent of employing the classification of all Naviculoid forms as applicable, especially to the species of Navicula. Van Heurck's analysis includes Pinnularia, Trachyneis, Diploneis, Caloneis, Neidium and Anomceoneis, which are here separated, while N. lyra and N. hennedyi are placed in different groups, although they are closely related. In other respects Cleve's divisions correspond, to some extent, to those of Van Heurck. The genus Navicula at one time included the following: Dictyoneis, Pleurosigma, Gyrosigma, Caloneis, Neidium, Diploneis, Frustulia, Trachyneis, Anomceoneis, Pinnularia and Stauroneis, and few forms with a raphe escaped. For this reason the diagnosis of the present genus is somewhat limited. Pleurosigma and Gyrosigma differ from Navicula in their outline, Dictyoneis in the double stratification, Caloneis in the marginal lines, Neid- ium in the median and terminal fissures, Diploneis in the horns, Frustulia in the terminal nodules, Trachyneis in the stratification of the valve, Anomceoneis in the longitudinal arrangement of the puncta, Pinnularia in the smooth costse and Stauroneis in the stauros. As the object of the present work is to aid the student of local forms in the identifi- cation of species by the briefest methods, the further discussion of the reasons for classi- fication will be left for his gratification in referring to the authorities on the subject. PUNCTATE CLEVE Valve elliptical to lanceolate; central nodule not stauroid or continued into lyriform spaces; striae distinctly or coarsely punctate, in radiate rows. NAVICULA MACULATA (BAIL.) CL. Valve lanceolate-elliptical, with produced or sub-rostrate ends; axial area narrow, wider near the ends and dilated to a rounded, transverse central area; strise radiate, 6 in 10 H, puncta, 7 in 10 M, in irregular, longitudinal rows. L. 90 to 120 /* (CL). Stauroneis maculata Bail. Navicula fischeri A. S. Blue clay. Along the coast, especially southward. PI. 24, Fig. 1. NAVICULA LATISSIMA GREG. Valve oblong-elliptical or elliptical-lanceolate, with sub-cuneate ends; axial area lan- ceolate, widened in the middle to an orbicular space; striae radiate, 7 in 10 n, puncta, 11 in 10 », the median striae alternating with short striae along the sides. L. 50-150 n (Cl). Blue clay. Pavonia, N. J., artesian well. PI. 24, Fig. 3. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 91 NAVICULA LATISSIMA VAR. ELONGATA (PANT.) CL. Valve elliptical-lanceolate, with rounded ends; striae and puncta closer than in the type form; axial area narrow, widened in the middle; terminal fissures hook-shaped, turned in different directions. Navicula humerosa var. elongata Pant. Fossil at Buckshutem, N. J. PI. 24, Fig. 5. NAVICULA FUCHSII PANT. Valve elliptical, with slightly produced apices; axial area wide, lanceolate; central area orbicular; strise alternately longer and shorter in the middle, 10-12 in 10 ju; puncta on the border of the axial area larger, elongated ; median fissures incrassate. Navicula humerosa var. fuchsii (Pant.) Cl. Navicula (lalissima var.?) fuchsii Pant. Port Penn, Delaware River. PI. 24, Fig. 6. NAVICULA HUMEROSA BREB. Valve lanceolate-elliptical or oblong-elliptical, with sub-cuneate or sub-rostrate ends; axial area narrow, lanceolate; central area rounded, somewhat transverse; terminal fissures hook-shaped, in the same direction; central pores incrassate; striae, 11 in 10 n, the middle alternately longer and shorter, closer at the ends. L. 60-86 /u. Variable in size, outline and fineness of striation. N. monilifera Cleve (N. granulata Breb.) differs in having coarser strise. Blue clay. Along the coast. PL 25, Fig. 5. NAVICULA PUSILLA WM. SM. Valve ovate-elliptical, with rostrate or sub-rostrate ends; axial area narrow; central area elliptical; striae radiate, 10-12 in 10 n in the middle where they are longer and shorter alternately, closer at the ends; median fissures somewhat incrassate, terminal in the same direction. L. 47 ju. Smith's Island, Delaware River. PL 25, Figs. 4, 6 ? Cleve gives the striae as 13-18 in the typical form, and 11-13 in varieties. In the form here figured the striation is as stated by De Toni, but is about 19 at the ends. Fig. 6 appears to be a small form of N. pusilla, near lanceolata Grun., at least accord- ing to the figure in "Arctic Diatoms," but not Gregory's figure. It occurs rarely in fresh water at Newtown Square. It may be a small form of N. punctulata and, if so, is probably accidental, as the material is entirely fresh-water. NAVICULA PUSILLA VAR. SUBCAPITATA N. VAR. Valve elliptical with rostrate-capitate and truncate ends; striae about 12 in 10 M in the middle where they are unequal; axial area narrow, slightly widened in the middle; central pores incrassate, terminal fissures in the same direction. Differs from type in out- line and centre. Pavonia, N. J., artesian well. Rare. PL 25, Fig. 8. 92 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY NAVICULA DELAWARENSIS GRTJN. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, lanceolate, widened in the middle; striae about 10 in 10 M in the middle, much closer at the ends; puncta in the middle, 9 in 10 n, closer and much smaller at the ends. L. 58-95 n- Cleve (Le Diatomiste, Vol. 2, p. 14) states that this form is very near N. pusilla but is much larger. Specimens from Smith's Island measure 58-65 n, from Wildwood, 95 /u in length. PI. 25, Fig. 3. NAVICULA PUNCTULATA WM. SM. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, central area rounded; strise, 11 in 10 /*, closer at the ends, a few shorter in the middle; puncta, 10 in 10 M. L. 54 fi. Navicula marina Ralfs. Port Penn, Delaware River (brackish water). PL 25, Fig. 9. "Although this species is described as marine in the Synopsis of Prof. Smith, I have never found it in purely marine localities" (Donkin). NAVICULA PUNCTATA VAR. ASYMMETRICA LAGERSTEDT Valve lanceolate, with rostrate ends; axial area narrow, central area transverse, irreg- ular; striae radiate, punctate, 12 in 10 p. L. 36 p. Navicula amphibola Cleve. Blue clay. PL 27, Fig. 15. NAVICULA BRASILIENSIS VAR. BICUNEATA CL., FORMA CONSTRICTA Valve oblong-elliptical, slightly constricted, with cuneate-rostrate ends; axial area narrow; central area dilated transversely and unilaterally; strise, 9 in 10 M; puncta closer at the border and in irregular longitudinal rows in the middle; terminal fissures small, hook- shaped, turned in the same direction. L. 93 /*. Corresponds closely to Cleve's variety except in the constriction. Blue clay. PL 25, Fig. 2. NAVICULA LACUSTRIS GREG. Valve lanceolate, sub-acute; axial area narrow; central area orbicular; strise radiate, 14 in 10 ju, punctate, the median puncta sometimes more distant than the others. Blue clay. Rare. PL 27, Fig. 12. LYRAT^: CL. Valve elliptical or elliptical-lanceolate; strise punctate, transverse; axial area narrow or indistinct; central area expanded on each side into lyre-shaped or horn-like blank spaces. NAVICULA PR^ETEXTA EHR. Valve elliptical; lateral areas not regular, with scattered puncta; strise radiate, 5 or 6 in 10 ju; puncta, 7 or 8 in 10 p; along the axial area, a single or double row of puncta; at THE DIATOMACEJS OF PHILADELPHIA AND VICINITY 93 the middle of the border, on each side, two striae approach each other closely with a short stria between them; terminal fissures small, in the same direction. L. 120 n- Port Penn, Delaware River. PI. 24, Fig. 2. While variable in size and striation, approaching N. hennedyi, this species, as here figured, is found in the Miocene and later deposits and is extant in most parts of the world. NAVICULA IRRORATA GREV. Valve oblong-elliptical, with cuneate-rostrate ends; striae, 7 or Sin 10 p., puncta, 7 in 10 p.; axial area bordered by puncta in unequal, transverse rows. L. 84 ju. Blue clay. Rare. PI. 24, Fig. 4. NAVICULA HENNEDYI WM. SM. Valve elliptical; areas semilanceolate; striae about 11 in 10 n, sometimes longer and shorter on the margin; short rows of transverse striae along the axial area. Blue clay. PI. 25, Fig. 12. Var. circumsecta Grun. — As in the type but with the lateral areas faintly striate or punctate. Var. manca A. S. — Valve lanceolate-elliptical, the lateral areas narrow and conver- gent toward the ends; short rows of transverse striae along the axial area; striae, 9 in 10 /*; central pores incrassate. Blue clay. PI. 25, Fig. 11. NAVICULA LYRA EHR. Valve elliptical, with rounded, sub-rostrate or sub-cuneate ends; lateral areas narrow; striae, 6 to 14 in 10 M (Cl.), punctate. L. 50-180 /*. Var. ehrenbergii Cl. — Lateral areas constricted in the middle, divergent at the ends. Cleve refers to Schmidt, Atlas, PI. 2, Fig. 25, which is not divergent at the ends. Along the coast. PI. 25, Fig. 10. A narrower form occurs which has the areas divergent. Var. ? — Valve elliptical, lateral areas narrow, convergent at the ends with short rows of punctate striae; marginal striae, 10 in 10 n, punctate. L. 60 p.. Squan River, N. J. PI. 20, Fig. 5. Var. dilatata A. S. — Valve elliptical, rostrate; lateral areas convergent in the middle and nearly parallel or convergent at the ends. Blue clay. PI. 25, Fig. 13. N. lyra is exceedingly variable in outline, fineness of striation and in the lateral areas. Intermediate forms occur approaching N. hennedyi and N. spectabilis. In N. hennedyi the lateral areas are broad, semilanceolate, not narrowed in the middle. In N. spectabilis the lateral areas are broad and narrowed in the middle. In N. lyra the lateral areas are narrow and either constricted or not in the middle. In many forms in 94 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY these three species the lateral areas are more or less striated or punctate. Cleve does not consider this a distinction of any importance, although certain varieties are founded upon it. All three species are very common in the blue clay and along the coast, but their varieties are too numerous to describe or figure. NAVICULA SPECTABILIS VAR. EMARGINATA CL. Valve elliptical; lateral areas broad, narrowed in the middle, delicately striated; mar- ginal striae, 10 in 10 M- L. 70 /x. Blue clay. PL 25, Fig. 7. NAVICULA PYG1VLEA KUETZ. Valve elliptical, appearing hyaline; axial and central areas faint; lateral areas con- vergent in the middle; striae indistinct, about 25 in 10 M. L. 23 ju. Brandywine Creek (Palmer). PL 27, Fig. 23. DECUSSATE CL. Valve elliptical or lanceolate; axial area narrow; central area small; striae punctate, in transverse and oblique, curved rows. NAVICULA PLACENTA EHR. Valve elliptical, with short, rostrate-capitate ends; axial area narrow; central area elliptical; striae in two directions, the transverse about 22 (to 27, CL) in 10 ju, the oblique striae crossing in both directions in curved lines appearing "coarser than the trans- verse" (Lewis). A very peculiar species which, as Cleve remarks, seems not to be allied to any other. L. about 35 p, quite constant in size. It is reported from Finland, Scotland, Hungary and New Zealand. Dr. Lewis found it in the Delaware River. It is occasional in the Schuyl- kill River and the blue clay, and very abundant on Marchantia and mosses on the wet rocks of the upper Wissahickon (F. J. Keeley). PL 27, Fig. 17. LlNEOLATjE CL. Valve more or less lanceolate; axial area narrow or indistinct; striae radiate or parallel, lineate, that is, with the puncta closer than the striae. NAVICULA RADIOSA KUETZ. Valve lanceolate with sub-rostrate apices; axial area indistinct; central area small; striae radiate in the middle, from 6 to 8 in 10 M, and convergent at the ends, about 12 in 10 M. L. 47 M. Very common in fresh water. PL 26, Fig. 17; PL 40, Fig. 9. NAVICULA PEREGRINA EHR. Valve lanceolate, obtuse; axial area narrow; central area large, rounded or slightly irregular; striae coarse in the middle, 5 in 10 /i, radiate; convergent at the ends, 7 or 8 in 10 ju. Abundant in brackish water. Delaware River. PL 26, Fig. 20. THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 95 NAVICULA CYPRINUS (WM. SM.) Valve lanceolate, slightly gibbous in the middle, sub-cuneate at the ends; axial area narrow; central area small; striae radiate in the middle, 10 in 10 /*, with shorter, transverse striae intermediate; transverse at the extreme ends. L. 82 /*. Navicula digito-radiata var. cyprinus (Ehr. ?) Wm. Sm. Whether the form here figured is Ehrenberg's or not, it is the species known as Pinnularia cyprinus Ehr. of Wm. Smith. Common in Shark River, N. J. PL 26, Fig. 21. NAVICULA REINHARDTII GRUN. Valve elliptical or elliptical-lanceolate, with broad, rounded ends; axial area narrow, widened at the ends to the width of the valve; central area widened transversely to an irreg- ular, quadrate space; striae coarse, 8 in 10 ju, distinctly lineate, alternately longer and shorter in the middle, radiate, nearly transverse at the ends. L. 59 M- Blue clay. Rare. PL 26, Fig. 22. NAVICULA LANCEOLATA VAR. ARENARIA (DONK.) CL. Valve lanceolate; axial area very narrow or indistinct; central area small, rounded; striae radiate, 11 in 10 ju in the middle, closer at the ends. L. 47-54 p. Navicula arenaria Donk. Shark River, N. J. PL 26, Fig. 23. NAVICULA SALINARUM GRUN. Valve elliptical-lanceolate with produced sub-capitate or rostrate ends ; striae radiate in the middle, longer and shorter; transverse at the ends, lineate. L. 32 ju Atlantic City, N. J. PL 26, Fig. 24. NAVICULA VIRIDULA VAR. ROSTELLATA KUETZ. Valve lanceolate with rostrate ends; axial area very narrow, central area orbicular; striae radiate in the middle, about 12 in 10 /z, convergent at the ends and closer. L. 43 /*. Common in fresh water. PL 26, Fig. 16. NAVICULA GRACILIS VAR. SCHIZONEMOIDES (EHR.) V. H. Valve lanceolate, obtuse; axial area widened in the middle; striae radiate in the middle, about 12 in 10 /z, transverse or slightly convergent at the ends. L. 45-60 p.. Occurs in gelatinous tubes; usually found free. Colletonema neglectum Thwaites. Fresh water. PL 26, Fig. 19. NAVICULA RAMOSISSIMA (AG.) CL. Valve lanceolate, sub-acute; axial area very narrow; central area scarcely widened; striae, 12 in 10 n, parallel throughout. L. 45 M- Micromega ramosissimum Ag. Schizonema smithii Kuetz. (not Ag.). East River, N. Y. PL 26, Fig. 14. 7 96 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY NAVICULA ANGLICA RALFS Valve elliptical, with sub-capitate or rostrate ends; axial area narrow, central area small; striae radiate, 12-13 in 10 /*, distinctly punctate. L. 26 /*. Fresh water. PL 26, Fig. 26. NAVICULA GASTRUM EHR. Valve elliptical, with rostrate ends ; axial area narrow, central area transverse or irreg- ular; stria? radiate, 9 in 10 n in the middle. L. 26 M- The form here figured approaches N. anglica. Kirkwood Pond, N. J. PL 26, Fig. 25. NAVICULA DICEPHALA WM. SM. Valve linear, with rostrate or rostrate-capitate ends; axial area narrow, central area rectangular, transverse; strise radiate, 12 in 10 M- L. 32 p. Fresh water. PL 27, Fig. 16. NAVICULA HUMILIS DONK. Valve elliptical, with broad, rostrate ends; axial area narrow; central area small; strise radiate and distant in the middle, convergent at the ends, coarse, appearing costate, averaging 9 in 10 ju- L. 19 M- As Donkin states, the striae are "very conspicuous." Navicula hungarica var. capitata (Ehr.) Cl. Navicula globiceps Lagerstedt, according to Cleve. Willistown, Pa. PL 27, Fig. 24. NAVICULA PINNATA PANT. ? Valve lanceolate, obtuse; axial area narrow, widened in the middle; stria? coarse, .7 in 10 M in the middle, radiate, 10 in 10 n at the ends and transverse, indistinctly lineate. L. 40 M. Near Navicula ardua Mann (Diat. Albatross Voy., Cont. U. S. Nat. Herbarium Vol. 10, Part 5, p. 336, PL 53, Fig. 2) which, however, is said to have "strictly unbeaded costse." Pavonia, N. J., artesian well. PL 27, Fig. 20. NAVICULA PENNATA A. S. Valve lanceolate, acute; axial area narrow; central area quadrate, transverse; striae radiate, coarse, 5 in 10 n, lineate. L. 68-95 M (Cleve). Pavonia, N. J., artesian well. PL 27, Fig. 22. NAVICULA INFLEXA GREG. Valve slightly elliptical-lanceolate, sub-acute, smooth at the ends; axial area narrow, widened in the middle; striae radiate, 11 in 10 n, lineate. Frustule in zone view constricted in the middle. L. 28-45 /*• Common along the coast. PL 27, Figs. 18 and 19. THE DIATOMACE^ OF PHILADELPHIA AND VICINITY 97 NAVICULA OBLONGA KUETZ. Valve linear-lanceolate, with broad, rounded ends; margin sometimes undulate; axial area narrow; central area large, orbicular; striae in the middle distant, radiate, convergent at the ends and curved or sharply bent, 7 in 10 n, lineate. L. 70-200 M (Cleve). Blue clay. Occasional in fresh water. PI. 27, Fig. 21. NAVICULA HASTA PANT. Valve lanceolate, gently tapering to the obtuse, produced ends; axial area lanceolate, widened to an orbicular space in the middle; striae radiate, the median coarse and quite distant, 5 in 10 n, becoming closer at the ends where they are 12 in 10 ju, lineate. The dis- tance between the median strise gives the appearance of a stauros. Occasional in the blue clay. PI. 27, Fig. 13. NAVICULA HASTA VAR. PUNCTATA N. VAR. Valve as in type but with strise in the middle distinctly punctate and reaching the median line. Greenwich Point, Philadelphia. PI. 27, Fig. 14. NAVICULA RHYNCOCEPHALA KUETZ. Valve lanceolate, with produced ends ; axial area indistinct ; central area small, rounded ; striae radiate in the middle, convergent at the ends, 10-11 in 10 p., punctate. L. 42 /j. Fresh water. Common. PL 31, Fig. 8. NAVICULA CRYPTOCEPHALA KUETZ. Valve lanceolate, with rostrate ends; axial area indistinct; central area small; striae, 16 in 10 /a, lineate, radiate in the middle, convergent at the ends. L. 28 n. Common in fresh water. Intermediate forms occur between N. rhyncocephala and N. cryptocephala. PI. 31, Fig. 9. NAVICULA LONGA (GREG.) RALFS Valve slender, rhombic, elongated, with acute ends; axial area indistinct; central area small; striae, 6 or 7 in 10 /*, radiate in the middle, elsewhere transverse; central pores closely approximate. L. 120 p.. New Rochelle, N. Y. PI. 31, Fig. 10. Cleve refers this form to N. directa var. remota Grun. Some specimens are found in this locality showing the "generally twisted" median line mentioned by Gregory. MESOLELE CL. Valve linear or elliptical; axial area narrow; central area quadrate; striae radiate, finely punctate. NAVICULA MUTICA KUETZ. Valve ovate, elliptical or lanceolate; axial area narrow; central area dilated into a stauros not reaching the margin; striae about 20 in 10 n, more distant in the middle, radiate, punctate. A punctum occurs on one side of the central nodule. 98 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY Reported from New Jersey in fresh water. I have not found it. The figure is from a specimen from another locality. PI. 26, Fig. 6. NAVICULA MINIMA GRtJN. Valve broadly elliptical, 13-15 ju in length; axial area narrow; central area small but with a quadrate pseudo-stauros which is striated; striae, about 28 in 10 p, radiate. Agrees closely with N. saugeri var. Grun. in V. H. Synopsis, PI. 14, Fig. 16, said to be intermediate between N. minima and N. atomoides Grun. N. minima var. atomoides Grun. is smaller. Common in water-troughs. PI. 26, Fig. 13. NAVICULA PUPULA VAR. BACILLARIOIDES GRUN. Valve linear, with rounded ends; axial area linear, expanding on both sides near the ends of the valve, forming a transverse lunate space; central area small, apparently expanded into a stauros, which, however, is striated; striae, 18 in 10 jt, at the middle, closer at the ends, punctate. L. 54 ju. Pavonia, N. J., artesian well. PI. 26, Fig. 9. BACILLARES CL. Valve linear or linear-elliptical, with broad ends; axial area narrow, the median line enclosed in siliceous ribs; striae finely punctate, more distant in the middle. NAVICULA BACILLUM EHR. Valve linear, with rounded ends; axial area enclosed in siliceous ribs and slightly ex- panded on each side at the ends; terminal nodules incrassate; central area small, elliptical; striae, 15 in 10 p in the middle, transverse, distinctly punctate, closer at the ends L. 47 ju- Fresh water. PI. 26, Fig. 10. Cleve describes the form as having slightly radiate striae in the middle. There is con- siderable difference in the descriptions of Cleve, Donkin, Grunow and Van Heurck, as also in all of the figures. NAVICULA AMERICANA EHR. Valve oblong-linear, with rounded ends, sometimes slightly constricted; axial area about one-half the width of the valve, dilated in the middle; striae parallel in the middle, radiate at the ends, 15-16 in 10 ju. A punctum is usually found in the central nodule. L. 55-154 M. Blue clay. Occasional in fresh water. PI. 26, Fig. 8. DECIPIENTES CL. Valve lanceolate, with obtuse ends; axial area narrow; central area orbicular; striae radiate in the middle and more distant. NAVICULA SEMEN EHR. Valve elliptic-lanceolate, with sub-rostrate, truncate apices; axial area narrow, sin- THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 99 uous; central area orbicular; terminal fissures small, hook-shaped; strise robust, 7 or 8 in the middle, closer at the ends, indistinctly punctate or lineolate. Blue clay. Not common. PL 26, Fig. 11. Cleve states that this form belongs to the post-glacial deposits and is found living only in the Hartz Mountains. NAVICULA INTEGRA WM. SM. Valve lanceolate with triundulate margins and rostrate-apiculate ends; strise radiate, more distant in the middle, 20-23 in n, punctate; axial area very narrow, central area rounded or elliptical. L. 33^13 /*. Pavonia, N. J., artesian well. Common in Chester River, Md. PL 26, Fig. 5. MICROSTIGMATIC.E CL. Valve lanceolate; axial area narrow; central area small, rounded; striae finely punctate, nearly parallel. (Includes here only the division Libellus.) NAVICULA TUMIDA (fiREB.) CL. Valve lanceolate, with rounded ends; axial area narrow, central area elliptical; raphe slightly sigmoid; striae, 13 in 10 n, finely punctate, a few shorter in the middle. Scoliopleura tumida (Bre"b.) V. H. Cape May, N. J. PI. 25, Fig. 1. NAVICULA GREVILLEI (AG.) CL. Frustules in gelatinous tubes, rectangular; zone with numerous longitudinal divisions. Valve elliptical-lanceolate, obtuse; axial area narrow, central area small; striae lineate, about 18 in 10 ju in the middle where they are slightly radiate and more evident, closer near the ends and transverse; median line with terminal pores distant from the ends. L. 60 M. Schizonema grevillei Ag. East River, N. Y. PL 31, Figs. 3 and 4. NAVICULA LIBELLUS GREG. Valve rhombic-elliptical, obtuse at the ends; axial area narrow, central rounded, small; strise punctate, slightly radiate, about 19 in 10 n; terminal fissures close to the ends, indistinct. L. 60 M- Cleve describes this form as having acute ends, while Gregory states that it is "more obtuse and broader than N. rhombica." Gregory's Figure 101 apparently shows the ends acute, but he says that the valve view is "rhombic or elliptic-lanceolate, broad, with ob- tuse ends" (Diat. of the Clyde, p. 57, PL 6). Hackensack Swamp, N. J. PL 31, Fig. 5. ORTHOSTICH^E CL. Valve lanceolate or elongated; axial area narrow; central area sometimes apparently dilated into a stauros; stria? punctate, the puncta in transverse and longitudinal rows. 100 THE DIATOMACKE OF PHILADELPHIA AND VICINITY NAVICULA CUSPIDATA KUETZ. Valve rhombic-lanceolate, with acute ends; axial area linear, narrow, not widened in the middle; strise transverse, 14-19 in 10 M (CL). L. 70-150 ju- Blue clay. Not uncommon in fresh water. PI. 26, Figs. 1 and 2. Fig. 2 represents an inner valve or stratum, with strong costse variable in size, formerly known as Surirella craticula Ehr. N. cuspidata var. ambigua (Ehr.) Cl. — Valve elliptical-lanceolate, with rostrate ends, smaller than the type and with finer striae. Crum Creek. PI. 26, Fig. 3. NAVICULA SPICULA (HICKIE) CL. Valve narrow, lanceolate with acute ends; axial area narrow, central area dilated into a stauros reaching the margin; transverse striae, 25-29 in 10 n, longitudinal closer. L. 50-130 (CL). Sometimes confused with N. crucigera. Stauroneis spicula Hickie. Newark, N. J. PI. 26, Fig. 4. NAVICULA CRUCIGERA (WM. SM.) CL. Valve lanceolate, narrow, with acute apices; central nodule a stauros reaching the margin but crossed by two or three coarser strise; transverse strise, 12 in 10 n, punctate, the puncta about 25 in 10 p. L. 80-100 /x (CL). Frustules in gelatinous tubes or free. Schizonema cmciger Wm. Sm. PL 26, Fig. 15. Reported as occurring in New York Bay, but I have not seen it. The figure is from a specimen from another locality. MINUSCULE CL. Valve lanceolate or elliptical, chiefly distinguished by the small size; axial area indis- tinct; central area small; striae radiate, very finely punctate. NAVICULA ATOMUS N^EGELI Valve elliptical, 6-8 M in length; strise radiate, 26-30 n, closer near the ends; axial area linear, scarcely widened in the middle. Water-troughs and ditches. Probably common, but frequently not noticed because of its minuteness. A mounting medium of the highest refractive index, such as realgar, is required to resolve the striae. In the figure the strise are drawn a little coarser than they appear in most specimens. PL 26, Fig. 12. CL. Valve lanceolate, axial area distinct; central area orbicular; striae coarse, indistinctly punctate, approaching the costae of Pinnularia. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 101 NAVICULA YARRENSIS GRUN. Valve elliptical-lanceolate, with rounded ends; axial area lanceolate, widened in the middle; striae, 5 in 10 /u. L. 97 p.. Cape May, N. J. Common. PL 25, Fig. 14. Fig. 15, a smaller form, 65 p. in length; striae, 6 in 10 p.. Fig. 16, 54 p. in length; striae, 8 in 10 p. (near var. valida Pant.). "Xii:- NAVICULA ELEGANS WM. SM. ^^^ Valve elliptical-lanceolate, with produced ends; axial area very narrow, central area large, orbicular; striae strongly divergent in the middle, slightly, if at all, convergent at the ends, curved toward the margin, indistinctly lineate, 9 in 10 p.. L. 95 p,. Blue clay. Not rare. PL 31, Fig. 1. Navicula elegans var. cuspidata Cl. — Valve as in type form but smaller and with rostrate apices; striae, 10 in 10 ju- L- 82 ju. Belmar, N. J. PL 31, Fig. 2. Cleve remarks that the type form is acute and the striae 9, while the var. cuspidata has 12 striae in 10 p.. In Fig. 1, PL 31, is represented a valve having 9 striae in 10 p., but not acute, while Fig. 2, with but slight variation in striae, is more cuspidate. It is probable there are intermediate variations. NAVICULA PALPEBRALIS BREB. Valve elliptical-lanceolate, with acute apiculate ends; axial area broad, lanceolate; striae radiate, lineate, about 11 in 10 p.. L. 60 p.. Along the coast. PL 31, Figs. 6 and 7. On Plate 40, Fig. 5, is represented an abnormal form of Navicula in which the central pores are in a line transverse to the longitudinal axis and each raphe is curved in a line which almost returns to the centre. The puncta are in curved lines radiating from the rounded hyaline centre. Pavonia, N. J., artesian well. Weissflog has described valves of Navicula somewhat similar in punctation. PINNULARIA EHR. (1843) (pinnula, a small feather) Valve linear or nearly so, with rounded ends; axial area broad; central and terminal areas large; costae smooth, transverse or radiating, usually convergent at the ends. The costae are channels on the inside of the valve, closed, except in the middle where elliptical foramina, opening into the interior of the valve, give rise through their terminal margins to the two longitudinal lines on each side of the valve. The raphe begins as a groove in the side of the conical central nodule and continues as a cleft at right angles to the plane of the surface of the valve, in which case the raphe forms a single line; if the raphe is inclined to the valve surface, then two lines appear in projection, the upper and lower edges of the cleft. In some forms the surface of the edge of the raphe on one side is folded or grooved for a considerable distance, and the opposite edge is elevated into a ridge or 102 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY tongue fitting into the groove. In such cases it is possible, in projection, to see the upper or outer edges of the raphe, the lower edges and the edges of the tongue and groove, thus showing four lines; sometimes, when the tongue and groove do not meet, six lines. The so-called inner channel is the part of the raphe on the inside of the tongue, and the so- called exterior channel is the part of the raphe on the outside of the tongue. If, in addition to this formation of the raphe, the plane of cleavage changes toward the terminal nodules, the lines will cross each other and, when two are superimposed, disappear altogether. For the careful examination of the raphe it is necessary to employ large forms, and it is advis- able to use nitrate of silver which remains in the raphe, and, as in slides mounted by Mr. F. J. Keeley, shows in a beautiful manner the entire outline of raphe and fissures. The terminal fissures owe their separation to the different directions taken by the two edges of the raphe on each side, one edge bending in a wide curve toward the end of the valve, show- ing two lines, the upper and lower edges of one side of the raphe when inclined to the plane of the surface, and the other edge of the raphe turning suddenly in an opposite direction and ending abruptly in a curve, giving rise to the appearance, by diffraction, of a punctum. PL 40, Figs. 13, 14 and 15. Endochrome consists of two chromatophores lying on the zones. Pinnularia is usually divided into the Majores, or larger, and the Minores, or smaller forms, the latter being further divided according to their striae. The following classification is chiefly that of Cleve. Majores. — Valve large, linear with parallel or slightly radiate striae and broad axial area. Gracillimce. — Valve small, stria? parallel or nearly so; axial area very narrow. Capitate. — Valve with capitate or rostrate ends; stria? radiate. Divergentes. — Striae strongly radiate. Brevistriatce. — Striae short. Distantes. — Striae distant. Tabellarice. — Striae radiate in the middle, strongly convergent at the ends. MarincE. — Marine forms. MAJORES PINNULARIA MAJOR (KUETZ.) WM. SM. Valve linear, usually slightly gibbous in the middle and at the ends; raphe oblique; axial area less than one-third the width of valve, convergent at the ends; striae, 7 or 8 in 10 n, radiate in the middle, convergent at the ends, crossed by a narrow band. L. ? to 300 n. Blue clay. Fresh water. Abundant at Middletown, Delaware Co. (T. C. Palmer). PI. 28, Fig. 4. Fig. 9, PI. 29, is one of a number of smaller forms which are difficult to determine, approaching P. viridis. PINNULARIA MAJOR VAR. PULCHELLA N. VAR. Valve strongly gibbous in the middle and gradually widened to the rounded ends; axial area broad, less than one-third the width of the valve, widened unilaterally in the middle; striae, 7 in 10 n, crossed by a band nearly as wide as the length of the costae and scarcely distinct. L. 273 p.. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 103 The central nodule is scarcely evident, probably because it is not so thick as in other forms. The outline is near to that of N. mesogongyla and certain forms of N. nobilis, differing from the latter in the median line, striae and band which is wider than that of P. latevittata var. domingensis Cl. Hammonton Pond, N. J. PI. 28, Fig. 2. A very beautiful form which I cannot find described or figured. It does not appear to be N. major var. turgidula Cl., which has a narrow band. In the fossil deposit from Hop- kinton, N. H., valves occur similar in outline but smaller. PINNULARIA NOBILIS EHR. Valve slightly gibbous in the middle and at the ends; median line complex; strise, 4 or 5 in 10 /i, slightly convergent or parallel at the ends, crossed by a band one-third as wide as the length of the strise. L. ? to 350 ju. Blue clay. Fresh water. PL 28, Fig. 1. PINNULARIA DACTYLUS EHR. Valve broad, linear, slightly gibbous in the middle; ends broad, rounded; median line not complex, sinuous; strise, 4 or 5 in 10 p., crossed by a very broad band. L. ? to 300 /*• Navicula gigas A. S. Blue clay. Fresh water. PL 28, Fig. 3. Forms occur which are with difficulty assigned to either nobilis or dactylus. PINNULARIA DACTYLUS VAR. DARIANA (A. S.) CL. Valve linear-lanceolate, obtuse; axial area broad, less than one-third the width of the valve; strise, 6 in 10 p, crossed by a broad band. L. 220 ju. Absecon, N. J. PL 29, Fig. 3. PINNULARIA DACTYLUS VAR. DEMERAR^E CL. Valve elliptical-lanceolate, with sub-cuneate ends; axial area lanceolate, broad in the middle; median line flexuose; strise radiate throughout, 6 in 10 ^- L- 150 ju. Blue clay. PL 29, Fig. 10. PINNULARIA GENTILIS (DONK.) CL. Valve linear, with rounded ends; axial area about one-fourth the diameter of the valve; strise radiate in the middle, convergent at the ends, 7 in 10 /*, crossed by a broad indistinct band. Fresh water. Not common. PL 29, Fig. 1. PINNULARIA TRIGONOCEPHALA CL. Valve linear, gibbous in the middle and at the cuneate ends; axial area wider between the middle and the ends, dilated to an elliptical space in the middle; strise, 6 in 10 p. L. 145 M. Blue clay. PL 29, Fig. 8. 104 THE DIATOMACEJE OF PHILADELPHIA AND VICINITY PINNULARIA VIRIDIS NITZSCH Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle; striae, 6 to 7 in 10 n, crossed by a band as wide as one-third the length of the striae. Common in fresh water. PI. 29, Fig. 2. Quite variable in size. Approaches P. major by intermediate forms as in Fig. 9, PI. 29. PINNULARIA VIRIDIS VAR. FALLAX CL. Valve linear, with rounded ends; axial area narrow, slightly widened in the middle; striae sometimes unilaterally interrupted, nearly parallel, 10 in 10 p. Elm, N. J. PI. 29, Fig. 4. In Fig. 2, PI. 30, a form is represented which corresponds closely to Navicula viridis var. B, of Wm. Smith. It is given as synonymous with var. fallax; it is bilaterally inter- rupted. Blue clay. PINNULARIA VIRIDIS VAR. ? Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle to a transverse fascia which is sometimes unilateral; striae, 14, in the middle, divergent, convergent at the ends and closer, crossed by a narrow band. L. 45-60 p.. Fascia some- times absent or very narrow. Northbrook, Pa. PI. 30, Fig. 17 (represents a form with wider area than usual). PINNULARIA VIRIDIS VAR. CAUDATA N. VAR. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, widened to an orbicular space in the middle; striae radiate in the middle, 11-12 in 10 jt, convergent and closer at the ends, crossed by a narrow band; median line with very long terminal fissures; terminal nodules noticeable because of the thickening of the edges of the terminal striae. L. 43 M- Fresh water, Newtown Square. Not common. PI. 30, Fig. 18. PINNULARIA SOCIALIS (PALMER) Valve linear, with rounded ends; axial area broad, one-third the width of the valve; striae slightly radiate in the middle, convergent at the ends, elsewhere parallel, 8 in 10 n, crossed by an indistinct band about one-third the length of the striae. L. 60-120 n- This species, discovered by Mr. Palmer near Media, Pa., is remarkable for the group- ing of the frustules "held with girdle sides together by a siliceous cementing of valve edges and enclosed in a common coleodenn." The usual number included in a group is four, but sometimes six or eight are noticed. The frustules adhere near their ends and are so firmly fastened that boiling in nitric acid and bichromate of potash for fifteen minutes will not separate them. Navicula socialis Palmer (Proc. Acad. Nat. Sci., Phila., 1910, p. 460, PI. 35). Media, Pa. PI. 29, Fig. 5. THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 105 PINNULARIA jESTUARII CL. Valve linear, with rounded ends; axial area broad, less than one-third the width of the valve; central area a transverse fascia; striae, 7 in 10 n, parallel except at the ends where they are slightly convergent; median line flexuose, with short, terminal semicircular fis- sures. L. 85 ju- Port Penn, Delaware River. Rare. PL 29, Fig. 6. GRACILLIM^E PINNULARIA MOLARIS (GRUN.) CL. Valve very convex, linear, with sub-cuneate ends; axial area narrow, expanded in the middle to a transverse fascia reaching the margin; striae divergent in the middle, con- vergent at the ends, 16 in 10 M- L- 60 /*. Fresh water. PL 29, Fig. 15. PINNULARIA LEPTOSOMA GRUN. Valve linear, rounded at the ends; axial area narrow; central area a broad transverse fascia; striae slightly divergent in the middle and convergent at the ends, 17 in 10 p. in the middle, closer at the ends. L. 56 n. Fresh water. Not common. PL 30, Fig. 10. CAPITATE PINNULARIA MESOLEPTA EHR. Valve linear, with triundulate margins and capitate ends; axial area narrow, widened in the middle; striae divergent in the middle, convergent at the ends, about 12 in 10 n. L. 34 ft. Common in fresh water. PL 29, Fig. 13. PINNULARIA MESOLEPTA VAR. STAURONEIFORMIS GRUN. Valve triundulate, capitate; axial area narrow, widened in the middle to a transverse fascia, broader at the margin; striae strongly divergent hi the middle and convergent at the ends, 9-10 in 10 ft. L. 70 ft. Pavonia, N. J., artesian well. Fresh water. PL 30, Fig. 20. PINNULARIA SUBCAPITATA GREG. Valve linear or linear-elliptical, with sub-capitate ends; axial area distinct, widened to a transverse fascia in the middle; striae divergent in the middle, convergent at the ends, 13 in 10 p. L. 32 A*. Fresh water. PL 29, Fig. 20. 106 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY PINNULARIA SUBCAPITATA VAR. PAUCISTRIATA GRUN. Valve linear-elliptical, with rounded ends; axial area gradually widened into a broad, transverse fascia; striae divergent in the middle, convergent at the ends, 11-12 in 10 p. L. 47 M. Fresh water. PI. 30, Fig. 16. PINNULARIA TERMES (EHR.) A. S. Valve linear, with concave margins and rostrate-capitate ends; axial area narrow, widened in the middle to an orbicular or sub-quadrate space ; striae divergent in the middle, scarcely, if at all, convergent at the ends, 10 in 10 ju. Pensauken, N. J., artesian well. PL 29, Fig. 17. This is, I believe, the form figured by Schmidt (Atlas, PL 45, Fig. 67). Cleve refers it to Pinnularia interrupta forma biceps, in which the central space is rhomboid. PINNULARIA TERMES VAR. STAURONEIFORMIS V. H. Valve linear, with concave margins and capitate-rostrate ends; axial area narrow, widened into a rhomboidal fascia, reaching the margin; striae, 10 in 10 /i, divergent in the middle, convergent at the ends. Pinnularia interrupta forma stauroneiformis Cl. Fresh water. PL 29, Fig. 14. PINNULARIA APPENDICULATA (AG.) CL. Valve linear, with subcapitate ends; axial area narrow; central area a transverse fascia; striae divergent in the middle, convergent at the ends, 16 in 10 p. L. 43 /it- Fresh water. Marl pits, Lenola, N. J. (Palmer). PL 29, Fig. 18. PINNULARIA BRAUNII GRUN. Valve linear-lanceolate, with capitate ends; axial area gradually widened toward the middle and expanded into a fascia reaching the margin; striae divergent in the middle, con- vergent at the ends, 11 in 10 ju- L- 52 p. Pensauken, N. J., artesian well. PL 29, Fig. 16. PINNULARIA MICROSTAURON (EHR.) CL. Valve convex, linear, tapering to sub-cuneate or sub-rostrate ends; axial area very narrow; central area a broad fascia; strire divergent in the middle, convergent at the ends, 12 in 10 M. L. 35 M. Pavonia, N. J., artesian well. PL 29, Fig. 19. This form does not exactly correspond to Cleve's diagnosis, as the ends are not broad. All species in the group Capitatee are quite variable. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 107 DlVERGENTES PINNULARIA DIVERGEN3 VAR. ELLIPTICA GRUN. Valve linear, with rounded ends; axial area widened in the middle to a transverse fascia; striae, 9 in 10 p., divergent in the middle, convergent at the ends. I.. 150 p. Fresh water. Not common in this locality. PI. 31, Fig. 13. PINNULARIA CARDINALICULUS CL. Valve linear, with rounded ends ; axial area wide, less than one-third the width of the valve, expanded to a transverse fascia; striae divergent in the middle and slightly conver- gent at the ends, 9 in 10 M- L. 97 /JL. Blue clay. PL 30, Fig. 1. As a rule, the median fissures in Pinnularia are turned inwards on the side of the longer edge of the terminal fissures, but not always. In this specimen the median fissures are turned slightly toward the side of the shorter edge of the terminal fissures. PINNULARIA LEGUMEN EHR. Valve linear, with more or less triundulate margins and broad, capitate ends ; axial area less than one-fourth the width of valve, widened in the middle; striae strongly divergent in the middle and convergent at the ends, 10 in 10 n- L. 84 p. Fresh water. May's Landing, N. J. PL 30, Fig. 3. PINNULARIA LEGUMEN VAR. ? Valve as in type, but with a transverse fascia; striae, 10 in 10 n, curved or bent near the ends. L. 84 ^. This form is not var. florentina Grun. May's Landing, N. J. (with the type). PL 30, Fig. 4. PINNULARIA BREBISSONII (KUETZ.) CL. Valve linear-elliptical, with rounded ends; axial area narrow, widened into a transverse fascia which is usually broader at the ends; striae divergent in the middle, convergent at the ends, about 12 in 10 p. L. 40-60 M (CL). Fresh water. Common. PL 29, Fig. 12; PL 31, Fig. 11. Variable in outline. PINNULARIA MORMONORUM (GRUN.) Valve linear, with rounded ends; striae divergent in the middle, convergent at the ends, 10 in 10 n; axial area rhombic-lanceolate, widened to a fascia usually reaching the border. L. 62 M. Navicula mormonorum Grun. Common near Willistown, Pa. This form is regarded by Cleve as P. brebissonii, but the axial area appears to dis- tinguish it. The valves are sometimes narrowed in the middle. PL 29, Fig. 11. 108 THE DIATOMACELE OF PHILADELPHIA AND VICINITY BREVISTRIAT^E PINNULARIA ACROSPK/ERIA (BREB.) CL. Valve linear, gibbous in the middle and at the ends; axial area about half the width of the valve; median line with approximate central pores; median area punctate; striae nearly parallel, radiate at the ends, 9 in 10 M- L- 32-180 n (Cl.). Blue clay. Recent, fresh water. PI. 30, Fig. 7. PINNULARIA ACROSPILERIA VAR. TURGIDULA GRUN. ? Valve strongly gibbous in the middle; ends rounded; striae, 12-13 in 10 M- L- 54 p. Blue clay, Gloucester, N. J., artesian well. PI. 30, Fig. 8. PINNULARIA BLANDITA N. SP. Valve linear, gibbous in the middle, and with rounded ends; striae radiate in the middle, convergent at the ends, 13 in 10 n; axial area about one-fourth the width of the valve, widened in the middle; median line with small semicircular terminal fissures. L. 65 M- Pavonia, N. J., artesian well. Rare. PI. 30, Fig. 25. PINNULARIA PARVA (EHR.) CL. VAR. ? Valve linear, tapering to the subcapitate ends; axial area broad, lanceolate; median line with approximate central pores and semicircular terminal fissures ; striae slightly diver- gent in the middle and convergent at the ends, 12 in 10 p. L. 58 p. Differs from the type in having finer striae. Atco, N. J. PI. 30, Fig. 14. PINNULARIA NODOSA FORMA CAPITATA CL. Valve triundulate, with capitate ends; axial area about one-fourth the width of valve; striae parallel, convergent at the ends, 10 in 10 n, sometimes interrupted in the middle. L. 47 M- Fresh water. Common. PI. 30, Figs. 15 and 19. PINNULARIA POLYONCA (BREB.) LEWIS Valve with triundulate margins, more inflated in the middle, with capitate ends ; axial area very broad; striae marginal, short, 9 in 10 n, divergent in the middle, convergent at the ends. L. 97 M- Kirkwood Pond, N. J. PI. 30, Fig. 21. The description of Kuetzing (Species Algarum, p. 85), where he states that the margins are "triundulate, the median inflation larger, apices rounded-capitate," appears to suffi- ciently distinguish this species, which I believe to be the same as Brun's Navicula peripunc- tata, except that the form figured (Especes Nouvelles, PI. 16, Fig. 11) is interrupted in the middle, a common variation in these forms. Cleve makes Navicula polyonca Breb. equal Pinnularia mesolepta, but at the same time he considers Lewis' form and also Brun's as equivalent to Navicula formica Ehr., and calls it Pinnularia nodosa var. formica Ehr. P. mesolepta has a narrower area than nodosa. I adhere to Lewis' identification, as in any case it is the form here figured and is nearly, if not quite, the same as Brun's species. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 109 DlSTANTES PINNULARIA LATA (BREB.) WM. SM. Valve linear-elliptical, broad; axial area broad, widened in the middle; striae slightly radiate in the middle, 3 in 10 M; median line oblique, the terminal fissures hook-shaped. L. 86 M. Blue clay. Not uncommon. PL 30, Fig. 23. PINNULARIA BOREALIS EHR. Valve linear, with rounded or sub-truncate ends; axial area about one-fourth the width of the valve, widened in the middle; median line with large hook-shaped terminal fissures; striae, 4 or 5 in 10 ^. L. 54 n- Blue clay. Occasional in fresh water in a smaller form. Specimens occur intermediate between P. lata and P. borealis. PL 30, Fig. 22; PL 31, Fig. 12. PINNULARIA BOREALIS VAR. SCALARIS (EHR.) CL. Valve narrow, linear; axial area broad, widened into a transverse fascia; striae, 8 in 10 AI. L. 32 n- Fresh water. PL 30, Fig. 24. TABELLARI.E PINNULARIA STOMATOPHORA (GRUN.) CL. Valve linear, with rounded ends; axial area less than one-third the width of the valve, gradually widened in the middle to a transverse fascia; on each side of the central nodule is a lunate space; striae divergent in the middle, convergent at the ends, 13 in 10 p; terminal fissures very long, bayonet shaped. L. 75 /*. Cleve describes a variety continua as not interrupted. In some forms the fascia is marked by very faint, short striae on the margin. Fresh water. Newtown Square. PL 30, Fig. 12. PINNULARIA GIBBA (KUETZ.) V. H. Valve linear, tapering to the subcapitate ends; axial area dilated in the middle; striae, 10-11 M, divergent in the middle, convergent at the ends. L. 80 M- Fresh water. PL 30, Fig. 5. PINNULARIA MESOGONGYLA (EHR.) CL. Valve linear, gibbous in the middle, ends subcapitate; axial area narrow, widened in the middle to a large orbicular space; striae strongly divergent in the middle, convergent at the ends, 11 in 10 n. L. 60 ju. Fresh water. Common. PL 30, Fig. 6. 110 THE DIATOMACE^ OF PHILADELPHIA AND VICINITY PINNULARIA STAUROPTERA (CHUN.) CL. Valve linear, with slightly triundulate margins tapering to the subcapitate ends; axial area more than one-third the width of the valve, slightly widened in the middle; median line with approximate central pores and semicircular terminal fissures; striae divergent in the middle, convergent at the ends, 11 in 10 M- L- 82 /i. May's Landing, N. J. PL 30, Fig. 13. Some of the forms are more triundulate than the specimen figured. PINNULARIA STAUROPTERA VAR. INTERRUPTA CL. Valve linear, tapering to the subcapitate ends; axial area broad, widened in the middle to a transverse fascia; striae divergent in the middle, convergent at the ends, 10 in 10 M; median pores approximate. L. 118 ju. Schuylkill River. PL 30, Fig. 11. PINNULARIA TABELLARIA (EHR.) CL. Valve linear, gibbous in the middle and tapering to the subcapitate ends; axial area about one-third the width of the valve, widened in the middle; median line with approxi- mate central pores and bayonet-shaped terminal fissures; striae sometimes unilaterally interrupted, divergent in the middle, strongly convergent at the ends, 9 in 10 p. L. 138 /n. Blue clay. Rare. PL 30, Fig. 9. The form here figured has coarser striae than in the type which is also usually more capitate. P. legumen has triundulate margins, P. mesogongyla has an orbicular space, while P. gibba has the space widened. According to Cleve, P. gibba has approximate central pores, as has also P. mesogongyla. In what I have considered to be P. legumen, the central pores are more approximate than in the other two species mentioned. In fact, all of the three resemble each other closely, and are variously named by different authors. The form of P. gibba here figured, which may be P. stauroptera, is not the typical form of Wm. Smith, which has a narrow area and central space. There are, however, among the typical speci- mens in H. L. Smith's Type Slide No. 275, smaller valves which show a resemblance. MARINE PINNULARIA RECTANGULATA (GREG.) CL. Valve linear, with abruptly rounded ends; axial area very narrow; central area large, somewhat quadrate; striae, 7-8 in 10 p.. L. 78 M- Navicula rectangulata Greg. Shark River, N. J. PL 29, Fig. 7. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 111 EPITHEMIA BREB. (isss) (epithema, a cover or lid) Frustules epiphytic, solitary, sometimes geminate, adherent on the ventral side at the ends; in zone view rectangular, sometimes tumid in the middle. Valve arcuate, having an interior costate stratum or transverse septa extending to the girdle, often detached, and an exterior valve surface with transverse rows of puncta. Central and terminal nodules not easily seen; in some species a true raphe is indicated. The resemblance between Epithemia and Eunotia has been already mentioned. In the shape and striation of the valves there is an approach to Cymbella. The genus is divided into two groups, one in which the costse alternate with double rows of puncta, as in E. turgida, and the other in which the rows of puncta are more than two. The endochrome usually consists of a band lying along the ventral zone and extending in two flaps on the valves. EPITHEMIA TURGIDA (EHR.) KTJETZ. Valve arcuate, with ends subcapitate ; costse radiate, 4 in 10 p, alternating with double rows of puncta. Median nodule central, the raphe curved toward the ventral edge which it closely follows. Parasitic on algse. Very common in fresh water, especially in ponds. In the figure the valve is asymmetrical with respect to the transverse axis, an unusual condition. PL 31, Fig. 14. EPITHEMIA ARGUS KUETZ. Valve with dorsal margin convex, and ventral margin nearly straight; ends rounded, constricted; costse robust, alternating with more than two rows of puncta; zone view rec- tangular, the thickened ends of the costse forming large nodules in a row along the edge of the valve next to the connecting zone. Cystopleura argus (Ehr.) Kunze. Common in fresh water. PL 31, Figs. 15 and 21. EPITHEMIA ARGUS VAR. ? Valve strongly arcuate on the dorsal side and concave on the ventral ; tapering to the rounded but not produced ends; costae at unequal distances, about 2 in 10 n; granules in transverse rows, 8 in 10 /u. L. 100 p. Pensauken, N. J., artesian well. PL 31, Fig. 16. EPITHEMTA MUELLERI A. S. ? Valve broad, convex, slightly arcuate, with obtuse, somewhat constricted apices; costse about 4 in 10 ju; striae, 12-14 in 10 M; in zone view the outline is rectangular, slightly tumid in the middle. L. 78 ju. Blue clay. PL 31, Fig. 17. 8 112 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY EPITHEMIA ZEBRA VAR. PROBOSCIDEA (KUETZ.) GRUN. Valve convex on the dorsal, concave on the ventral side; costse, 3-4 in 10 jtc, slightly radiating; apices recurved, capitate. Blue clay. PI. 31, Fig. 18. EPITHEMIA GIBBERULA VAR. PRODUCTA GRUN. Valve narrow, lunate, with produced and arcuate apices; costse radiate, 3-4 in 10 n ; strise, 16-18 in 10 n, punctate. L. 58 M, usually smaller. Blue clay. PL 31, Fig. 19. EPITHEMIA MUSCULUS KUETZ. Valve short, strongly arcuate on the dorsal, concave on the ventral side; apices slightly produced; costse radiate, about 5 in 10 n; striae, 15 in 10 n, punctate. L. 20-60 y.. Shark River, N. J. PL 31, Fig. 20. EPITHEMIA MUSCULUS VAR. CONSTRICTA (BREB.) V. H. Frustule elliptical, slightly constricted in the middle. Valve convex on the dorsal, straight on the ventral side; costse about 4 in 10 M; striae about 18 in 10 p, finely punctate. L. 45 M. Epithernia succinta Br6b. New Rochelle, N. Y. PL 31, Fig. 22. RHOPALODIA MUELLER (Rhopalodes, like a war club) Frustule in zone view linear, linear-elliptical (in our species), or clavate. Valve reni- form or lunate; a raphe, not visible in some species in the usual position of the valve, is found along the convex edge or keel. Median and terminal nodules, although very small, can be determined. The name is more appropriate to the African species which are clavate. Two species only are found in this locality. The chief distinction between Epithemia and Rhopalodia is in the position of the raphe and the nodules. In R. gibba and R. ventricosa the costse are parallel and not radiate since the valves are not lunate. Chromatophore a single band irregularly divided. RHOPALODIA GIBBA (KUETZ.) MUELLER Valve linear, arcuate on the dorsal, straight on the ventral side, reflexed at the extrem- ities. Costse, 6-7 in 10 M; strise about 14 in 10 M- L. 80-200 M- Fresh water. Common. PL 31, Fig. 23. In this species the raphe and nodules can be seen only when the valve is examined at right angles to its usual position. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 113 RHOPALODIA VENTRICOSA (KUETZ.) MUELLER Valve gibbous in the middle on the dorsal side, straight on the ventral side, with reflexed apices; costse, 7 in 10 ju; striae, 14-16 in 10 n- L. 40-100 n. The median nodule appears as a minute depression in the middle of the dorsal side. The two species usually occur together. Epithemia gibba var. ventricosa Kuetz. PL 31, Fig. 24. SURIRELLOIDE.E The Surirelloidese are usually understood to include the genera Surirella, Podocystis, Cymatopleura and Campylodiscus, all of which resemble each other more or less, either in having a keel or markings like the divisions of the keel in Surirella and a median line, or pseudoraphe. The genus Nitzschia also has a keel, but it does not border each side of the valve as in Surirella, being found either near one margin or between it and the centre. Certain of the Surirellae are allied to the group Tryblionella of the Nitzschise, while forms of Stenopterobia are distinguished with difficulty from the group Sigmata. The following arrangement, therefore, is intended to include all genera having a keel or something which resembles it. Hantzschia. — Valve asymmetrical ; keels of the two valves opposite each other. Nitzschia. — Valve asymmetrical; keels not (usually) opposite each other. Surirella. — Valve usually symmetrical; a keel on each border. Cymatopleura. — Valve without an elevated keel, but with markings like those of Suri- rella; undulated in zone view. Campylodiscus. — Valves saddle-shaped. HANTZSCHIA GRUN. (1377) (named after C. A. Hantzsch) Valve arcuate, with rostrate ends; keel puncta short, prolonged into costse or extend- ing across the valve; median nodule rudimentary; the keels of the two valves opposite each other. Distinguished from Nitzschia chiefly by the position of the keels. According to Mereschkowsky, however, two species of Nitzschia, N. lanceolata and N. spectabilis, show the same peculiarity. Chromatophores four, two on each of the zones (Mereschkowsky). HANTZSCHIA AMPHIOXYS (EHR.) GRUN. Valve slightly arcuate, with rostrate apices; keel puncta, 8 in 10 M; striae transverse, 16-18 in 10 M, punctate. L. 60 ». Quite variable. Fresh water. PI. 32, Fig. 9. 114 THE DIATOM AGILE OF PHILADELPHIA AND VICINITY HANTZSCHIA AMPHIOXYS VAR. MAJOR GRTJN. Valve as in type, but the keel puncta are 5 in 10 ^ and the striae are 11-12 in 10 p. L. 71 n. H. amphioxys var. major Grun. is stated to be 120 M in length. The present form is smaller but corresponds in puncta and striation. Van Heurck remarks that it approaches H. virgata. Abundant in sand ripples on the beach at Cape May, N. J. PI. 39, Fig. 4. Fig. 6, PI. 39, is drawn from an authentic specimen of Wm. Smith's Nitzschia amphi- oxys, from England, and is introduced for comparison. The central nodule is not evident. Fig. 3, PI. 39, is from a specimen from an unknown locality. The keel puncta are 6 and the striae 16 in 10 p. HANTZSCHIA VIRGATA (ROPER) GRUN. Valve arcuate on the dorsal side, nearly straight on the ventral side, with rostrate, recurved apices; keel puncta prolonged to one-third the width of the valve, 4 in 10 /u; trans- verse striae, 9-10 in 10 y.. L. 115 n. Shark River, N. J. (Kain). I have not been able to find this form on our coast. The figure is drawn from a speci- men from another locality. PI. 32, Fig. 23. HANTZSCHIA MARINA (DONK.) GRUN. Valve with dorsal margin slightly arcuate, ventral margin straight; apices rostrate and recurved; keel puncta, 6 in 10 p., prolonged into costae across the entire valve; trans- verse striae, 12 in 10 ju, in double rows of alternating puncta between the costae. L. 106 ju. Epithemia marina Donkin. Along the coast. PI. 32, Fig. 22. NITZSCHIA HASSALL (1845), em. GRUN. (isso) (named after Christian L. Nitzsch, of Halle) Frustules usually free, sometimes enclosed in tubes or united into a filament. Valves keeled, the keels of the two valves usually diagonally opposite (see Hantzschia) ; keel puncta short or prolonged. According to Mereschkowsky, there are at least two endochrome plates placed trans- versely on the zones; sometimes there are from four to six plates, in one species twenty granules and in another no trace of any endochrome whatever. The following analysis is that of Grunow as given in Cleve and Grunow's "Arctic Diatoms," and adopted and illustrated by Van Heurck in his "Synopsis." GROUPS 1. Tryblionella. — Keel very excentric, valve often folded; keel puncta indistinct, usually the same in number as the striae. 2. Panduriformes. — Valve broad, constricted in the middle, with more or less evident fold; keel very near the edge; keel puncta quite evident or apparently wanting. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 115 3. Apiculatce. — Keel very near the edge; valve linear or somewhat narrower in the middle; strise on the longitudinal fold fainter than on the remaining surface, or wanting; puncta not in quincunx. 4. Pseudo-Tryblionella. — Keel more or less close to the edge; valve with a more or less deep longitudinal fold over which the strise are spread in the same way as over the remain- ing surface; keel puncta always distinct. 5. Circumsutce. — Valve with more or less wide longitudinal fold; keel very excentric; keel puncta quite evident; surface of valve irregularly punctate and also traversed by rows of delicate puncta which belong to a different layer of the valve. 6. Dubice. — Like the group Pseudo-Tryblionella, but the valves are not so much folded; frustules sometimes narrowed in the middle. The separation of species is difficult and, in part, doubtful. Keel excentric. 7. Bilobatce. — Like the group Dubise, but with more central keel and so forming a transition to the group Pseudo-Amphiprora; valves without longitudinal folds. 8. Pseudo-Amphiprora. — Valve with quite central, sharp keel, arcuate, without longi- tudinal fold; keel puncta always evident; frustule narrowed in the middle with more or less marked central nodule. Includes two species not found in this locality. 9. Perry a. — Valve arched with very sharp central keel; not narrowed in the middle; keel puncta mostly on short or long lines which are sometimes interrupted. Includes six species not found in this locality. 10. Epithemioidece. — Keel excentric; keel puncta extended into costse across the entire valve. 11. Grunowia. — As in the group Epithemioidese, except that the cost® are shorter, not extending across the valve; keel very excentric. 12. Scalares. — Like Grunowia, but with sharper, somewhat excentric keel; transverse section of frustule quadrangular. 13. Insignes. — Like Scalares, but with more central keel so that many of the forms are near the group Perry a; frustule somewhat sigmoid. 14. Bacillaria. — Keel central or nearly so; valve somewhat arched; keel sharp, as in the group Insignes. 15. Vivaces. — Keel moderately excentric; valve, according to position, semi-lanceolate, with keel puncta in short rows, or lanceolate with quite central keel. The valves have in many positions a resemblance to Hantzschia, so that N. vivax frequently becomes con- founded with a form of H. amphioxys. The median keel puncta are not distant and a central nodule is not evident as is the case in all species of Hantzschia. 16. Spathulatce. — Like the group Bacillaria, but usually with very delicate striated valves; keel in valve view usually bordered with two parallel lines. 17. Dissipates. — Like Vivaces and Spathulatse, but with smaller central keel and without parallel lines. Valves usually small, very delicately striated; no central nodule. 18. Sigmoidece. — Keel quite central; no parallel lines; frustule sigmoid; valve without longitudinal furrow; keel puncta not extended; no central nodule evident. 19. Sigmata. — Like Sigmoideae, but with a more excentric keel. 20. Obtusce. — Like Sigmata, with a more or less excentric keel which has in the middle a small bending to the inside; middle keel puncta somewhat more distant than the others, and between them a central nodule evident. 116 THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 21. Spectabiles.— Valve large, slightly arcuate, with excentric keel; no longitudinal folds; keel puncta somewhat extended over the valve but much less than in the group Insignes, and often scarcely perceptible. 22. Lineares. — Keel somewhat excentric, but less than in Spectabiles; frustule straight, sometimes a little constricted in the middle, so that a transition is shown to the groups Dubise and Bilobatae. Valve without longitudinal fold; keel puncta round or somewhat angular, scarcely extended. 23. Lanceolate. — Valve lanceolate, linear-lanceolate or rarely elliptical, with very excentric keel; not folded; keel puncta not extended. 24. Nitzschiella. — Valve with excentric keel and long, produced apices. TRYBLIOXELLA NITZSCHIA TRYBLIONELLA HANTZSCH Valve elliptical-lanceolate, with subacute apices; longitudinal fold well marked; striae coarse, transverse, 5 in 10 n; indistinct puncta intermediate between the striae. L. 45 n. Quite variable. Blue clay. PI. 32, Fig. 8. NITZSCHIA GRANULATA GRUN. Valve elliptical or elliptical-lanceolate; striae in double rows, each row of three or four small puncta along the margin and rows of large puncta about 6 in 10 n across the valve. L. 28-44 M. Blue clay. Along the coast. PI. 32, Fig. 3. NITZSCHIA NAVTCULARIS (BREB.) GRUN. Valve elliptical-lanceolate, with acute apices; striae on one side a double row of large and small puncta, and on the other side radiate short rows of large puncta, 7 in 10 n; middle of valve hyaline. L. 35-60 /n. Blue clay. Not common. PI. 32, Fig. 4. NITZSCHIA COMPRESSA (BAIL.) Valve elliptical-lanceolate, sometimes acuminate; striae, 6 or 7 in 10 n, coarsely punctate. L. 56 //. Pyxidicula compressa Bailey. Nitzschia punctata (Wm. Sm.) Grun. Tryblionella punctata Wm. Sm. Common along the coast. PI. 39, Fig. 7. Var. minor (H. L. Smith). — Valve acuminate; striae, 8 in 10 ft. L. 22 ft. Pyxidicula compressa var. minor H. L. Smith, Type Slide No. 431. PL 39, Fig. 8. The smaller forms occur northward, while the larger are found southward. This is unquestionably Bailey's form, as indicated by his figure and by the fact that it is found everywhere along the coast. Wm. Smith's T. punctata is the same species, although the puncta are smaller. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 117 PANDURIFORMES NITZSCHIA PANDURIFORMIS GREG. Valve elliptical, constricted in the middle, with sub-cuneate apices; longitudinal fold, with a punctate longitudinal line; striae transverse and oblique, 15 in 10 M; keel puncta, 6 in 10 p.. L. 108 n. Along the coast. More often found southward. PL 39, Fig. 2. NITZSCHIA PANDURIFORMIS VAR. MINOR GRUN. Valve elliptical, constricted in the middle, with cuneate apices; keel puncta, 9 in 10 ju; striae in transverse and oblique lines about 20 in 10 n; longitudinal fold bordered by a punctate line. L. 34 /*. Pavonia, N. J., artesian well. PL 32, Fig. 5. The var. continua Grun. is reported as occurring in Shark River. It varies in having the longitudinal fold punctate. It is also usually smaller than var. minor. APICULATjE NITZSCHIA APICULATA (GREG.) GRXJN. Valve oblong-linear, with cuneate-apiculate apices; striae punctate, apparently inter- rupted or pervious, about 18 in 10 ju. L. 26 /*. Chester River, Md. PL 32, Fig. 6. The puncta are continued across the valve, but are less distinct on the fold. The figure shows the entire frustule with the fold on each valve. The valves are sometimes slightly constricted. NITZSCHTA ACUMINATA (WM. SM.) GRUN. Valve linear, sometimes slightly constricted in the middle, with acuminate apices; longitudinal fold entirely without or with indistinct striae; keel puncta not evident; striae, 14-15 in 10 M. L. 82 M. Port Penn, Delaware River. PL 32, Fig. 13. NITZSCHIA PLANA WM. SM. Valve linear; apices acute, slightly constricted in the middle; longitudinal fold further from the keel than the margin, broad, with scattered puncta; strise subtle, irregular, inter- rupted, about 18 in 10 M! keel puncta oblong, 3-6 in 10 ju. L. 100-170 ju. Blue clay. Along the coast. PL 32 Fig. 2. 118 THE DIATOMACE^E OF PHILADELPHIA AND VICINITY PSEUDO-TRYBLIONELLA NITZSCHIA LITORALJS VAR. DELAWARENSIS GRUN. Valve linear, with obtusely rounded cuneate ends, scarcely, if at all, constricted in the middle; longitudinal fold wide; keel puncta, 5 or 6 in 10 n, sometimes confluent; striae ob- scure, about 21 in 10 M- L. 75 /*. Delaware River. PI. 32, Fig. 12. This form is drawn from a slide of Christian Febiger containing an abundance of speci- mens from Delaware City, and marked "Nitzschia dubia." CIRCUMSUTJS NITZSCHIA CIRCUMSUTA (BAIL.) GRUN. Valve elliptical, sometimes more than 200 n in length; longitudinal fold more or less conspicuous; keel puncta about 4 in 10 n, the middle distant with the appearance of a nodule; striae irregular, subtle, finely punctate, frequently interrupted. Surirella circumsuta Bail. Tryblionella scutellum Win. Sm. Common in brackish water. PL 32, Fig. 1. DUBLE NITZSCHIA DUBIA WM. SM. Valve linear, scarcely, if at all, constricted in the middle, with cuneate, produced, apiculate apices, somewhat recurved; keel very excentric; puncta sometimes partly pro- longed, about 9 in 10 n; striae, 20-24 in 10 M- L. 93 p. Reported from along the New Jersey coast. I have not seen it. It is generally regarded as fresh-water. Slides sometimes labelled N. dubia are in reality N. litoralis var. dela- warensis. PL 39, Fig. 5. The figure is drawn from a specimen from another locality. BILOBAT^E NITZSCHIA BILOBATA WM. SM. Valve linear-lanceolate, constricted in the middle, apiculate at the ends; keel puncta 6 in 10 ju, prolonged unequally across part of the valve, the two median sub-remote; strise, 16 in 10 n. Frustule oblong, truncate, constricted in the middle. L. 120 p. Shark River, N. J., Chester River, Md. PL 32, Figs. 10 and 11. EPITHEMIOIDEjE NITZSCHIA EPITHEMIOIDES GRUN. Valve linear, with cuneate, rostrate apices; slightly constricted on the keel side; keel puncta, 8 or 9 in 10 //, extending as costae across the valve; striae delicate, 22 in 10 /*. L. 47 /i. Brackish water, Long Island Sound. PL 32, Fig. 21. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 119 GRUNOWIA NITZSCHIA TABELLARIA GRUN. Valve rhomboidal, inflated in the middle; apices produced; keel puncta extend in costse across half of the valve, 7 in 10 p.; strise transverse, about 22 in 10 ft. L. 20 /*• Dimerogramma sinuatum Thwaites. Nitzschia sinuata var. tabellaria (Grun.) V. H. Schuylkill River. Not common. PI. 32, Fig. 7. SCALARES NITZSCHIA SCALARIS (EHR.) WM. SM. Valve linear, with obtusely conical apices; costs transverse, extending more or less to one-third the width of the valve, 3 or 4 in 10 n; striae, 9 or 10 in 10 n, punctate. Length of valve quite variable, up to 480 p (Cleve) . A well-known form, abundant in salt marshes and more or less brackish water. PI. 33, Fig. 6. (To the right of the figure is an outline of the valve reduced one-third.) INSIGNES NITZSCHIA INSIGNIS GREG. Valve nearly linear or linear-lanceolate; apices broad, slightly produced, obtuse; keel puncta extended into short costae, 4 or 5 in 10 n; strise about 14 in 10 p. Length variable up to 400 p. Delaware Bay. PI. 33, Fig. 8. BACILLARIA NITZSCHIA PAXILLIFER (0. F. MUELLER) HEIBERG Frustules united in a filament, afterwards free; valve lanceolate with nearly central keel; keel puncta, 7-9 in 10 ju; strise about 21 in 10 M- L. 110 M- Vibrio paxillifer O. F. Mueller. Batillaria paradoxa Gmelin. Nitzschia paradoxa (Gmelin) Grun. Brackish water or streams subject to its influence. PL 33, Figs. 13 and 14. Otto Frederick Mueller, in 1786, published at Copenhagen a work on "Infusorial Ani- malcules," including a description of a Vibrio which he named paxillifer, obviously alluding to the partially-extended frustules bearing at the end a tablet-like bundle. Two years later, Gmelin described the same form as Bacillaria paradoxa, a name still used. Heiberg, however, in 1863, placed the form under Nitzschia where it properly belongs and called it Nitzschia paxillifer (O. F. Mueller). I have adopted Heiberg's name. Perhaps the most remarkable of all diatoms. Many species possess the power of mo- tion, which, however, is evident only in the free frustule. In N. paxillifer, the movement of the frustules occurs without the loss of continuity or adherence to each other, so that, while at one time the adnate frustules form a narrow filament, like that of Fragilaria, at another 120 THE DIATOMACEffl OF PHILADELPHIA AND VICINITY time they move laterally to their extreme length and form a thread of frustules adherent at their ends, later resuming their original position. The motion is repeated at intervals of from five to ten seconds. No satisfactory explanation of the movement has ever been made. In the filamentous form the frustules adhere to water-plants. VIVACES NITZSCHIA FLUMINENSIS GRUN. Valve lanceolate, apices produced; keel puncta, 4-6 in 10 ft, partly extended in short costse; striae transverse, 14-15 in 10 n, punctate; keel without a pseudo-nodule. L. 73 n. Common at Greenwich Point, Philadelphia. PI. 32, Fig. 16. The form here figured is smaller than the type, which is from 130-160 n in length. SPATHULATjE NITZSCHIA SPATHULATA BREB. Frustule linear, truncate, dilated at the ends; zone with longitudinal folds; valve lance- olate, keel central; apices acute, with an elevated appendage; keel puncta, 5-6 in 10 n; striae very fine. L. 56 n. Atlantic City and Cape May, N. J. (Lewis). PI. 40, Fig. 3. DISSIPATE NITZSCHIA DISSIPATA (KUETZ.) GRTJN. Valve lanceolate, with sub-rostrate apices; keel excentric; keel puncta about 6 in 10 n; Btriae, 14 in 10 n. L. 20-40 M- Fresh and brackish water. PI. 40, Fig. 7. SIGMOIDE.E NITZSCHIA MACILENTA GREG. Frustule sigmoid, truncate at the ends; valve linear, with sub-acute apices and nearly central keel; keel with 5-6 puncta in 10 n; striae obscure, about 25 to 28 (?) in 10 p. Length variable, up to 490 M. As the valve is usually seen when the keel is on the margin, the outline (reduced one- third, shown to the left of the figure) is, as a rule, sigmoid. Delaware Bay. PI. 33, Fig. 7. NITZSCHIA VERMICULARIS (KUETZ.) HANTZSCH Valve linear, sigmoid, attenuated toward the obtuse ends; keel puncta, 9 in 10 n, quite distinct; striae very fine. L. 105 ju. Fresh-water pools. PI. 32, Fig. 24; PI. 33, Fig. 9. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 121 SIGMATA NITZSCHIA SIGMA (KUETZ.) WM. SM. Frustule linear, sigmoid; valve linear, slightly sigmoid, tapering to the sub-acute apices; keel excentric, puncta, 8 in 10 p.; striae, 20-24 in 10 n. L. to 250 p. Along the coast. PI. 39, Fig. 13. NITZSCHIA SIGMATELLA GREG. Valve linear, sigmoid, slightly attenuated toward the obtuse apices; keel excentric, puncta, 8-10 (?) in 10 M; striae delicate, 25-30 hi 10 /i. L. to 400 p. The keel puncta are quite obscure. Nitzschia curvula Wm. Sm. Nitzschia sigma var curvula (Wm. Sm.) De Toni. Fresh water. Hammonton Pond; May's Landing, N. J. PL 33, Figs. 4 and 5. Gregory remarks that the keel puncta are seen in some specimens. In both of the forms figured I have counted 30 striae in 10 n, but, after many examinations, I have not been quite certain about the keel puncta. The general appearance of the valves in any position is that of a Stenopterobia or Surirella anceps, with which it occurs. NITZSCHIA CLAUSII HANTZSCH Valve linear, slightly sigmoid, tapering to the sub-capitate ends; keel puncta, 11 in 10 n; striae subtle. L. 40 ju- Abundant in Ridley Creek, Delaware Co. (Palmer). PL 32, Fig. 20. OBTUSE NITZSCHIA OBTUSA WM. SM. Frustule sigmoid, rounded at the ends; keel somewhat excentric, inflexed in the middle, the two median puncta distant; keel puncta, 5-6 in 10 M; striae, 26 in 10 M- L- to 300 p. Along the coast. PI. 39, Fig. 16. NITZSCHIA OBTUSA VAR. FLEXELLA H. L. SMITH Valve more attenuate at the ends than the type and smaller. PL 39, Fig. 14. NITZSCHIA OBTUSA VAR. SCALPELLIFORMIS GRUN. Valve linear, with apices unilaterally truncate; keel excentric; keel puncta, 8 in 10 /*; striae, 26 in 10 M- L- 48 p. Along the coast. PL 32,. Fig. 17. 122 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SPECTABILES NITZSCHIA SPECTABILIS VAR. AMERICANA GRTJN. Frustule linear, slightly constricted in the middle, with sub-cuneate ends; valve linear, slightly arcuate, tapering to the sub-rostrate ends; keel excentric, keel puncta sometimes confluent, 4-6 in 10 p, prolonged into short costse; striae distinct, 14 in the middle, 18 at the ends in 10 n (but variable in different specimens). L. 186 M- Blue clay, especially at Tioga St. PI. 33, Fig. 3; PI. 39, Fig. 1. This is, probably, one of the most beautiful of the Nitzschise. It sometimes, according to De Toni, reaches a length of 520 ju. Grunow states that his variety is found in the S. Bridgeton deposit. In a slide of Mceller labelled "Bridgeton, Maine," I find specimens identical in every respect with the Philadelphia form. LINEARES NITZSCHIA LINEARIS (AG.) WM. SM. Valve linear, slightly inflexed in the middle; keel excentric; keel puncta, 8-9 in 10 M, the two median distant; striae about 30 in 10 ju. Frustules in zone view narrowed toward the ends, truncate. L. 75 M- Very common in fresh water. PI. 32, Fig. 18. Fig. 20, PI. 40, a transverse section of frustule. LANCEOLATE: NITZSCHIA PALEA (KUETZ.) WM. SM. Valve linear-lanceolate, slightly rostrate at the apices; keel puncta, 10 in 10 p., the median not distant; striae, 33-36 in 10 /*; zone view linear, with rounded ends. L. 25-65 p.. Fresh water. PL 32, Fig. 15. NITZSCHIA AMPHIBIA GRTJN. Valve lanceolate, apices sometimes slightly produced, rounded; keel puncta, 8-9 in 10 M; striae, 16 in 10 /i. L. 20-32 ju. Fresh water. PL 32, Figs. 14 and 25. NITZSCHIA COMMUNIS RAB. Frustule linear, slightly attenuated at the obtuse ends; valve elliptical-lanceolate, attenuated toward the obtuse ends; keel puncta, 12 in 10 ju; striae more than 30 in 10 p. L. 35 ji. Fresh water. PL 32, Fig. 19. NITZSCHIA INTERMEDIA HANTZSCH Valve linear-lanceolate; keel puncta, 8 in 10 n; strise about 24 in 10 M- L- 100 ju. Crum Creek. Not common. PL 33, Fig. 2. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 123 NlTZSCHIELLA NITZSCHIA LONGISSIMA (BREB.) RALFS Valve linear-lanceolate, with exceedingly long horns or beaks; keel puncta about 10 in 10 n; strise about 16 in 10 /j. L. to 500 ju. Shark River, N. J. PI. 33, Fig. 1. Forma parva V. H. — Keel puncta, 10-12 in 10 /*. L. 70 /u. East Park Reservoir, Philadelphia. PI. 33, Fig. 10. Differs from N. closterium (Ehr.) Wm. Sin. in the keel puncta. The type form occurs in brackish and salt water. The occurrence of the variety in fresh water is another instance of the finding of presumably brackish forms in the water supply of the city. If these cases prove to be unusual, it may be because of one of two rea- sons. The Schuylkill River, before the building of the dam at Fairmount, was tidal as far as the Falls of Schuylkill, and brackish influences, while not now existent, may have caused the growth of forms which now survive. Another reason may be that the opening of the locks at Fairmount Dam may cause a slight admission of brackish forms from tidal water below. The abundance of the brackish species appears to indicate that the first reason is the more plausible. NITZSCHIA REVERSA WM. SM. Valve lanceolate, extended into beaks or horns curving in opposite directions; keel puncta not evident; striae, "20-26" in 10 ». L. 70 p.. Brackish water. Abundant in Duck Creek, Delaware River. PI. 33, Fig. 11. NITZSCHIA ACICULARIS (KUETZ.) WM. SM. Valve lanceolate, with beaks or horns about half the length of the median part of the valve; keel puncta, 18 in 10 p.; strise exceedingly delicate, "about 40 in 10 /u." L. 45 n. Fresh water. Darby Creek. PI. 33, Fig. 12. HOMCEOCLADIA AG. (1827) (homoios, like, and clados, a branch) Frustules like Nitzschia, but enclosed in branching or simple tubes. HOMCEOCLADIA FILIFORMIS WM. SM. Frustule linear, tumid in the middle, obtuse at the ends ; valve linear-lanceolate, with somewhat acute apices; keel central or nearly so; keel puncta, 8 in 10 /*; striae delicate. L. 108 M- Fresh and brackish water. Newark, N. J. PI. 33, Fig. 15. 124 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SURIRELLA TURPIN (1828) (named after Dr. Suriray, a physician of Havre) Valve linear, elliptical or ovate; pseudoraphe linear or lanceolate; a marginal keel forming wings or ate seen in zone view; costse short or reaching the pseudoraphe, frequently with intercostal strise more or less evident. The genus is divided by Grunow according to the length and form of the costse. I include Stenopterobia. Section 1. — Costse of nearly equal width throughout, reaching the pseudoraphe. Section 2. — Costse short or marginal. Section 3. — Costse dilated at the margin, attenuated toward the pseudoraphe. Section 4. — Valve having the appearance of Nitzschia, with inconspicuous alse (Stenopterobia). The endochrome consists of two laminate chromatophores, one on each valve. The auxospores are single, originating from the union of two frustules (H. L. Smith). SECTION 1 SUKIRELLA BISERIATA (EHR.) BREB. Valve lanceolate, subacute at the ends; costse robust, about 2 in 10 n, parallel in the middle, radiate at the ends; pseudoraphe narrow. L. 100 n. Surirella bifrons Ehr. Fresh water. PI. 39, Fig. 12; PI. 35, Fig. 2 (smaller form). SURIRELLA LINEARIS WM. SM. Valve linear, with cuneate ends, slightly constricted in the middle; costse parallel, 2-3 in 10 p. L. 90 ju- Fresh water. PI. 35, Fig. 8. SURIRELLA AMPHIOXYS WM. SM. Valve oblong-linear, with cuneate ends; pseudoraphe narrow; costae, 3-4 in 10 strise, 14-16 in 10 n, somewhat radiate. L. 34-54 /*. Surirella moelleriana Grun. Fresh and brackish water. Common along the coast. PL 35, Figs. 12 and 13. SURIRELLA ROBUSTA EHR. Valve linear-ovate; pseudoraphe wide; alse prominent; costse wide, 1J4 in 10 Frustule in zone view clavate. L. 200-365 M- Fresh water. PI. 36, Fig. 2. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 125 SURIRELLA SPLENDIDA (EHR.) KUETZ. Valve ovate; costse, 1J^ to 2 in 10 n; pseudoraphe linear, narrow. L. 125-200 pi- Fresh water. PI. 35, Fig. 3. S. splendida is smaller than S. robusta and wider in proportion, but, as intermediate forms occur, it is difficult to distinguish between them. SURIRELLA ELEGANS EHR. Valve ovate, rounded at one end and acute at the other; pseudoraphe lanceolate, narrow; costae, \}/%"-»J.i^K;;. #$•• V»-9'"0° " f ° nr?r?Q ° " °*>° ''JWt&f/ $frloo^;o1 AD NATUR. DELIN. C. S. BOYEK PLATE 7 FIG. PAGE BIDDULPHIA 1-2-3-4 Biddulphia biddulphiana (Smith) .... 31 5 Biddulphia rhombus (Ehr.) Wm. Sm 32 6 Biddulphia granulata Roper. . . 7 Biddulphia turgida (Ehr.) Wm. Sm 32 8 Biddulphia smithii (Ralfs) V. H 32 9 Biddulphia \scvis Ehr 10 Biddulphia la-vis Ehr. Sporangial frustules (260 diam.). . . 33 EUNOTOGRAMMA 11 Eunotogramma ktve Grun DlATOMACEJE OF PHILADELPHIA PLATE 7 0 o oo o a oo o 000 OO 0 00 0 0 000000 oooooooooooooooo OOVOOOOOOOOOOOOOo po o~ooOoqo^ 10 AD NATUR. DELIN. C. S. BOYER PLATE 8 FIG. PAGE RHABDONEMA 1-2-3 Khabdonema arcuatum (Lyng.) Kuetz 35 4-5-6 Rhalxlonema adriaticum Kuetz 36 7 Khabdonema minutuin Kuetz. . . 36 TABELLARIA 8-9-10 Tabellaria flocculosa (Roth) Kuetz 36 11-12 Tabellaria fenestrata (Lyng.) Kuetz 36 GRAMMATOPHORA 13-14 Grammatophora marina var. subtilissima (Bail.) V. H. . 37 15-16 Grammatophora angulosa var. hamulifera (Kuetz.) Grun. 37 17-18 Grammatophora marina (Lyng.) Kuetz 37 19-20 Grammatophora islandica Ehr 37 21 Grammatophora serpent ina Ralfs. . 37 STRIATELLA 22-23 Striatella unipunctata (Lyng.) Ag 38 24 Striatella interrupta (Ehr.) Heib 38 ATTHEYA 25 Attheya decora West 38 DlATOM.H'K.K OF PuiLAUELl'lIlA PLATE 8 o iiiifij /3 n U ii.-; Is r it i|jr AD XATUIt. IJKL1N. C. 8. 1>OYE1( PLATE 9 FIG. PAGE LICMOPHORA 1-2 Licmophora flabellata (Carm.) Ag 39 3-4 Licmophora lyngbyei Kuetz 40 5 Licmophora chrenbergii (Kuetz.) Grun 40 6-7 Licmophora paradoxa (Lyng.) Ag 39 8-9 Licmophora ovulum Mer 39 10 Licmophora baileyi (Edw.) Grun 40 11 Licmophora gracilis (Ehr.) Grun 39 12-13 Licmophora gracilis var. elongata (Kuetz.) De Toni 39 14-15 Licmophora tincta (Ag.) Grun 40 DlATOMACEJE OF PHILADELPHIA PLATE 9 /O AD NATUR. DELIN. C. S. BOYER PLATE 10 FIG. PAGE MERIDION 1-2-3 Meridiem circulare (Grev.) Ag 40 DIATOMA 4 Diatoma vulgare var. grande (Wm. Sm.) Grun 42 5-6 Diatoma anceps (Ehr.) Kirchn 42 7-8 Diatoma hiemale (Lyng.) Heih 42 9-10 Diatoma vulgare Bory 42 PLAGIOGRAMMA 11 Plagiogramma tessellatum Grev 43 12 Plagiogramma obesum Grev 43 13 Plagiogramma pygma-um Grev 43 14 Plagiogramma wallichianum Grev 43 EUNOTOGRAMMA 15 Eunotogramma Iseve Grun 33 OPEPHORA 16-19 Opephora schwartzii (Grun.) Petit 43 17 Opephora pinnata var. lanceolata n. var 44 18 Opephora pacifica (Grun.) Petit 43 FRAGILARIA 20-21 Fragilaria virescens Ralfs 44 22-23 Fragilaria arctiea Grun 44 24-25-27-28-29 Fragilaria undata Wm. Sm 44 26 Fragilaria undata Wm. Sm., var.? 44 30 Fragilaria construens (Ehr.) Grun 45 31 Fragilaria harrisonii (Wm. Sm.) Grun 45 34 Fragilaria capucina var. mesolepta Rab 45 35 Fragilaria parasitica (Wm. Sm.) 45 36 Fragilaria sp.? 45 37 Fragilaria linearis Cstr 45 RHAPHONEIS 38 Rhaphoneis amphiceros Ehr 46 39-40 Rhaphoneis amphiceros var. rhombica Grun 46 41 Rhaphoneis belgica var. intermedia Grun 46 SYNEDRA 32-33 Synedra radians Kuetz 49 DlATO.MACE.E OF PHILADELPHIA PLATE 10 c /J HSU! V AD NATUIi. DEUX. C. S. BOYEU PLATE 11 FIG. PAGE SYNEDRA— Continued 1-5-6 Synedra ulna (Nitzsch) Ehr. Sporangial 47 2 Synedra danica Kuetz 48 3 Synedra biceps (Kuetz.) A. S 48 4-7-11 Synedra ulna (Nitzsch) Ehr 47 8 Synedra capitata Ehr 48 9-18 Synedra acus Kuetz 48 10 Synedra fulgens (Grev.) Wm. Sm 50 12-13 Synedra goulardi Breb 48 14-15-16 Synedra pulchella (Ralfs) Kuetz 48 17 Synedra pulchella var. abnormis Macchiati ? 48 DlATOMACE^E OF PHILADELPHIA PLATE 11 i- as: •;:'•/• II '7 :H =::: /O AD NATUR. DELIN. C. S. BOYER PLATE l« FIG. PAGE SYNEDRA— Continued 1 Synedra oxyrhynchus var. undulata Grun 48 2 Synedra pulchella var. flexella n. var 49 3 Synedra affinis Kuetz 50 4 Synedra affinis var. talmlata (Ag.) V. H 50 5-6 Synedra vaucherite var. parvula (Kuetz.) Hal) 49 7 Synedra affinis var. parva (Kuetz.) V. H 50 8 Synedra radians (Kuetz.) H. L. S 49 DIMEROGRAMMA 9-10 Dimerogramma tnarinum (Greg.) 46 11 Dimerogramnia surirclla (Ehr.) Grun 46 12-13-14 Dimerogramnia minus (Greg.) Ralfs 47 TRACHYSPHENIA 15 Trachysphenia australis Petit 47 ACTINELLA 16-17-18 Actinella punctata Lewis 54 ASTERIONELLA 19-20-21 Asterionella formosa Hass 50 22 Asterionella inflata Heib 50 EUNOTIA 23 Eunotia hemicyclus (Ehr.) Ralfs 53 24-25 Eunotia lunaris (Ehr.) Grun 53 DlATOMACK^E OF PHILADELPHIA PLATE 12 AD XATDR. DELIN. C. S. BOYER PLATE 13 FIG. PAGE EUNOTIA— Continued 1-2 Eunotia major (Win. Sm.) Rab 51 3 Eunotia gracilis (Ehr.) Rab 51 4 Eunotia major (Wm. Sin.) Rab. (intermediate form) ... 51 5 Eunotia praerupta Ehr 53 6-7 Eunotia pectinalis (Kuetz.) 52 8-10 Eunotia pectinalis var. undulata Ralfs 52 9 Eunotia pectinalis var. solierolii (Kuetz.) 52 11 Eunotia luna Ehr. var.? 52 12 Eunotia pectinalis var. ventricosa Grun 52 13 Eunotia robusta Ralfs (E. scalaris Ehr.) 53 14 Eunotia robusta Ralfs (E. prioritis Ehr.) 53 15 Eunotia robusta Ralfs (E. decadon Ehr.) 53 16 Eunotia robusta Ralfs (E. octodon Ehr.) 53 17-22 Eunotia robusta Ralfs (E. heptodon Ehr.) 53 18 Eunotia bactriana Ehr 54 19 Eunotia praerupta var. bidens Grun 53 20 Eunotia bidentula Wm. Sm 54 21 Eunotia robusta Ralfs (E. diadema Ehr.) 53 23 Eunotia praerupta Ehr. var.? 53 24 Eunotia robusta Ralfs (E. triodon Ehr.) 53 25 Eunotia robusta Ralfs (E. tetraodon Ehr.) 53 26 Eunotia formica Ehr. var. ? 54 27 Eunotia biceps Ehr 53 28-29 Eunotia sp.? 54 30-31 Eunotia veneris Kuetz 52 32 Eunotia nymanniana Grun 51 DlATOMACE^: OF PHILADELPHIA PLATE 13 AD NATUR. DELIN. C. S. BOYER PLATE 14 FIG. PAGE AMPHIPRORA 1-2 Amphiprora pulchra Bail , . 68 3 Amphiprora alata Kuetz 68 4 Amphiprora conspicua Grev 68 5 Amphiprora paludosa Wm. Sm 68 6-7 Amphiprora ornata Bail 68 TROPIDONEIS 8-9 Tropidoneis lepidoptera (Greg.) Cleve 69 SCOLIOTROPIS 10-11 Scoliotropis latestriata var. amphora Cleve 69 DlATOMACE.E OF PHILADELPHIA PLATE 14 AU NATDK. DELIN. C. S. BOYEH PLATE 15 FIG. PAGE AMPHORA 1 Amphora robusta Greg 65 3 Amphora crassa Greg 65 4 Amphora obtusa Greg 67 5-6-19 Amphora proteus Greg 65 7 Amphora ovalis (Breb.) Kuetz 65 8-18 Amphora cofTanformis (Ag.) Kuetz 66 9-10 Amphora lineolata Ehr 66 11 Amphora areolata Grun 66 12-21 Amphora ostrearia Breb 66 13 Amphora Isevis Greg 66 14-15 Amphora ocellata var. cingulata Cleve 67 16 Amphora angusta var. eulensteinii Grun 67 17 Amphora arenaria Donk 67 20 Amphora acuta Greg 66 AURICULA 2 Auricula mucronata (H. L. Smith) Peragallo 69 DlATOMACE^; OF PHILADELPHIA PLATE 15 SLI AD NATUR. DELIN. C. S. BOYER PLATE 16 FIG. PAGE ACHNANTHES 1-2 Achnanthes longipes Ag 58 3 Achnanthes brevipes Ag 59 4-5-6 Achnanthes subsessilis Kuetz 59 7-8 Achnanthes inflata (Kuetz.) Grun 59 9 Achnanthes coarctata (Br6b.) Grun 59 10-11-12 Achnanthes lanceolata (Breb.) Grun 59 13 Achnanthes danica (Floegel) Grun. (lower valve) 60 14-15 Achnanthes exigua Grun 59 16-17 Achnanthes linearis forma curta H. L. Smith. ... 59 COCCONEIS 18 Cocconeis scutellum var.? 57 19-20 Cocconeis placentula Ehr 57 21 Cocconeis scutellum Ehr. (upper valve) 57 22 Cocconeis dirupta Greg, (lower valve) 58 23-24 Cocconeis pediculus Ehr 57 25-26 Cocconeis pellucida Grun 58 27-28 Cocconeis scutellum var. ornata Grun 57 29 Cocconeis placentula var. lineata (Ehr.) V. H 58 ANORTHONEIS 30-31 Anorthoneis excentrica (Donk.) Grun 56 DlATOMACE^E OF PHILADELPHIA PLATE 16 lo II '7 AD NATUR. DELIN. C. S. BOYER PLATE 17 FIG. PAGE FRUSTULIA 1 Frustulia lewisiana (Grev.) De Toni 77 2 Frustulia rhomboides (Ehr.) De Toni 77 3 Frustulia rhomboides var. amphipleuroides Grun 77 4 Frustulia vulgaris (Thwaites) De Toni 77 5 Frustulia interposita (Lewis) De Toni 78 6 Frustulia rhomboides var. saxonica (Rab.) De Toni .... 77 BRFBIS8ONIA 7 Br6bissonia bu'ckii (Kuetz.) Grun 79 8 I3r6bissonia palmerii n. sp 80 AMPHIPLEURA 9 Amphipleura pellucida Kuetz 78 10-11 Amphipleura rutilans (Trentepohl) Cl 78 ANOMCEONEIS 12 Anormi'oneis serians (Breb.) Cl 80 13 Anomoeoneis serians forma minor 80 14 Anomoconeis follis (Ehr.) Cl 80 TRACHYNEIS 15 Trachyneis aspera var. intermedia Grun 79 MASTOGLOIA 16 Mastogloiu kinsmanii Lewis 87 17 Mastogloia angulata Lewis 87 18 Mastogloia lanceolata Thwaites 87 19 Mastogloia smithii Thwaites 87 20 Mastogloia elegans Lewis 87 21-22-23 Mastogloia apiculata Wm. Sm 87 24 Mastogloia exigua Lewis 87 DlATOMACE-ffi OF PHILADELPHIA PLATE 17 II, ' 17 AD NATUR. DELIN. C. S. BOYER m is- 2.3 PLATE 18 FIG. PAGE CYM BELLA 1 Cymbella aspera (Ehr.) Cl 61 2 Cymhclla cymbiformis (Kuetz.) Er6b 62 3 Cymbella cistula (Hempr.) Kirchn 62 4 Cymbella lanceolata (Ehr.) Kirchn 62 5 Cymbella mexicana (Ehr.) A. S 62 6 Cyml>ella naviculiformis Auerswald 60 7 Cymbella tumida (Brei>.) V. H 62 8 Cymbella philadelphica n. sp 63 9 Cymbella ehrenbergii Kuetz 60 10 Cymbella heteropleura (Ehr.) Kuetz 60 11 Cymbella rhomboidea n. sp 63 12 Cymbella turgida (Greg.) Cl. var.? 63 13 Cymbella sinuata Greg 61 14 Cymbella ventricosa Kuetz 62 15-19 Cymbella excisa (Kuetz.) De Toni ; 61 16 Cymbella amphicephala Najgeli (il 17 Cymbella cuspidata Kuetz 60 18 Cymbella affinis Kuetz 61 20 Cymljella gracilis (Rab.) Cl 64 21 Cymbella prostrata (Berk.) Cl 63 22 Cymbella ventricosa Kuetz.? 62 23 Cymbella turgida (Greg.) Cl 63 24 Cymbella triangulum (Ehr.) Cl 63 25 Cymbella lacustris (Ag.) Cl 64 DlATOMACEJE OF PHILADELPHIA PLATE 18 AD NATUR. DELIN. C. S. BOYER PLATE 19 FIG. PAGE GOMPHONEIS 1 Gomphoneis mamilla (Ehr.) Cl 70 2 Gomphoneis herculaneum (Ehr.) Cl 70 GOMPHONEMA 3 Gomphonema montanum Schum 71 4 Gomphonema geminatum Lyng 71 5 Gomphonema acuminatum var. turns (Ehr.) Cl 71 6-12 Gomphonema laneeolatum var. insignia (Greg.) Cl 71 7 Gomphonema acuminatum var. coronata (Ehr.) Cl 71 8 Gomphonema constrictum Ehr 72 9-10 Gomphonema sphserophorum Ehr 72 11 Gomphonema acuminatum var. turris (Ehr.) Cl.? 71 13 Gomphonema ventricosum Greg 73 14 Gomphonema intricatum Kuetz 72 15 Gomphonema scquale Greg 72 16 Gomphonema sarcophagus Greg 72 17 Gomphonema parvulum var. micropus (Kuetz.) Cl 73 18-19 Gomphonema angustatum Kuetz 72 20 Gomphonema acuminatum var. trigonocephala (Ehr.) Cl. 71 21 Gomphonema augur Ehr 72 22 Gomphonema capitatum Ehr 72 23 Gomphonema olivaceum Lyng 73 24 Gomphonema brasiliense var. demerarae Grun.? 73 RHOICOSPHENIA 25-26-27 Rhoicosphenia curvata (Kuetz.) Grun 56 DIATOMACE.E OF PHILADELPHIA PLATE 19 =2.3 '-A AD NATUIi. DELIN. C. S. BOYEI! PLATE 20 FIG. PAGE DICTYONEIS 1 Dictyoneis marginata var. maxima n. var 79 2 Dictyoneis marginata var. commutata Cleve 79 3 Dictyoneis marginata var. typica Cleve 78 DIPLONEIS 4 Diploncis crabro var. pandura (Br6b.) Cl 85 6 Diploneis campylodiscus (Grun. )C1 86 7-8 Diploneis gruendleri (A. S.) Cl 85 9 Diploneis crabro Ehr. var.? 85 10 Diploneis excentrica n. sp 85 11 Diploneis fusca var. delicata (A. S.) Cl 85 12 Diploneis puella (Schum.) Cl 85 13 Diploneis crabro var. pandurella Cl.? 85 14 Diploneis elliptica (Kuetz.) Cl 84 15 Diploneis crabro var. expleta (A. S.) Cl 85 10 Diploneis gemmata (Grev.) Cl 86 17 Diploneis smithii (Br6b.) Cl 84 NAVICULA 5 Navicula lyra Ehr. var.? 93 DIATOM ACE. K OF PHILADELPHIA PLATE 20 /S. AD NATUK. DELIN. C. S. BOYER PLATE 21 FIG. PAGE CALONEIS 1 Caloneis permagna (Bail.) Cl 2 Caloneis permagna var. lewisiana n. var 82 3 Caloneis silieula (Ehr.) Cl 81 4 Caloneis silieula var. inflata (Grun.) Cl 81 5 Caloneis brevis var. vexans (Grun.) Cl 82 6-7 Caloneis wardii Cl 82 8 Caloneis trinodis (Lewis) 81 9 Caloneis trinodis (Lewis) var.? 81 10 Caloneis powellii (Lewis) Cl 83 18 Caloneis formosa (Greg.) Cl 82 NEIDIUM 11 Neidium affine (Ehr.) Pfitzer 83 12 Neidium affine var. genuina forma minor Cl 83 13 Neidium affine var. amphirhyncus (Ehr.) Cl 83 14 Neidium amphigomphus (Ehr.) Pfitzer 83 15 Neidium hitchcockii (Ehr.) Cl 84 16 Neidium productum (Wm. Sm.) Cl 83 17 Neidium iridus (Ehr.) Cl 84 DlATOMACEJE OF PHILADELPHIA PLATE 21 13 AD NATUR. DELIN. C. S. BOYER PLATE 22 FIG. PAGE PLEUROSIGMA 1 Pleurosigma strigosum Wm. Sm 74 2 Pleurosigma rigidum Wm. Sm 75 3 Pleurosigma angulatum (Quekett) Cl 74 4 Pleurosigma obscurum Wm. Sm 74 5 Pleurosigma formosum Wm. Sm 73 6 Pleurosigma naviculaceum Bre'b 74 7 Pleurosigma sestuarii Br6b 74 8 Pleurosigma virginiacum H. L. Smith 74 DlATOMACE^: OF PHILADELPHIA PLATE 22 8 AD NATUR. DELIN. C. S. BOYER PLATE 23 FIG. PAGE GYROSIGMA 1 Gyrosigma strigilis (Wm. Sm.) Cl 76 2 Gyrosigma balticum (Ehr.) Cl 75 3 Gyrosigma hippocampus (Ehr.) 75 4 Gyrosigma simile (Grun.) 76 5 Gyrosigma acuminatum (Kuetz.) Cl 76 6 Gyrosigma scalproides (Rab.) Cl 76 7 Gyrosigma parkeri var. stauroneioides Grun 75 8 Gyrosigma spencerii var. nodifera Grun 76 9 Gyrosigma fasciola (Ehr.) Cl 77 DlATOMACE-iE OF PHILADELPHIA PLATE 23 AD NATUR. DELIN. C. S. BOYEH PLATE 24 FIG. PAGE NAVICULA 1 Navicula maculata (Bail.) Cl 90 2 Navicula practexta Ehr 92 3 Navicula latissima Greg 90 4 Navicula irrorata Crev 93 5 Navicula latissima var. elongata (Pant.) Cl. . . 91 6 Navicula fuchsii Pant 91 DlATOMACE^i OF PHILADELPHIA PLATE 24 5" AD NATUR. DELIN. C. S. BoYER PLATE 25 FIG. PAGE NAVICULA 1 Navicula tumida (Breb.) Cl 99 2 Navicula brasiliensis var. bicuneata Cl. forma constricta. 92 3 Navicula delawarensis Grun 92 4-6 Navicula pusilla Wm. Sm 91 5 Navicula humerosa Brdb 91 7 Navicula spectabilis var. emarginata Cl 94 8 Navicula pusilla var. subcapitata n. var 91 9 Navicula punctulata Wm. Sm 92 10 Navicula lyra Ehr 93 1 1 Navicula hennedyi var. manca A. S 93 12 Navicula hennedyi Wm. Sm 93 13 Navicula lyra var. dilatata A. S 93 14 Navicula yarrensis Grun 101 15 Navicula yarrensis Grun. (smaller form) 101 16 Navicula yarrensis Grun. var.? 101 DlATOMACE^: OF PHILADELPHIA PLATE 25 AD NATUR. DELIN. C. S. BOYER PLATE 26 FIG. PAGE NAVICULA 1-2 Navicula cuspidata Kuctz 100 3 Navicula cuspidata var. ambigua (Ehr.) Cl 100 4 Navicula spicula (Hickie) Cl 100 5 Navicula integra Wm. Sm 99 6 Navicula mutica Kuetz 97 8 Navicula amerieana Ehr 98 9 Navicula pupula var. hacillarioides Grun 98 10 Navicula hacillum Ehr 98 1 1 Navicula semen Ehr 98 12 Navicula atomus Nsegeli 100 13 Navicula minima Grun 98 14 Navicula ramosissima (Ag.) Cl 95 15 Navicula crucigera (Wm. Sm.) Cl 100 16 Navicula viridula var. rostellata Kuetz 95 17 Navicula radiosa Kuetz 94 19 Navicula gracilis var. schizonemoides (Ehr.) V. H 95 20 Navicula peregrina Ehr 94 21 Navicula cyprinus (Wm. Srn.) 95 22 Navicula reinhardtii Grun 95 23 Navicula lanceolate var. arenaria (Donk.) Cl 95 24 Navicula salinarum Grun 95 25 Navicula gastrum Ehr 96 26 Navicula anglica Ilalfs 96 DIPLONEIS 7 Diploneis oculata (Breb.) Cl 86 STAURONEIS 18 Stauroneis frickei var. angusta n. var 88 DlATOMACE^E OF PHILADELPHIA PLATE 2C AD NATUR. DELIN. C. S. BOYER PLATE 27 FIG. PAGE STAURONEIS— Continued 1 Stauroneis phcenicenteron Ehr 88 2 Stauroneis acuta Wm. Sm 89 3 Stauroneis americana A. S 89 4 Stauroneis anceps var.? 88 5 Stauroneis anceps var. gracilis (Ehr.) Cl 88 6 Stauroneis salina Wm. Sm 89 7 Stauroneis anceps var. amphicephala (Kuetz.) Cl 88 8 Stauroneis anceps var.? 88 9 Stauroneis anceps var.? 88 10 Stauroneis crucicula (Grun.) Cl 89 1 1 Stauroneis smithii Grun. . . 89 NAVICULA 12 Navicula lacustris Greg 92 13 Navicula hasta Pant 97 14 Navicula hasta var. punctata n. var 97 15 Navicula punctata var. asymmetrica Lagerstedt 92 16 Navicula dicephala Wm. Sm 96 17 Navicula placenta Ehr 94 18-19 Navicula inflexa Greg 96 20 Navicula pinnata Pant.? 96 21 Navicula oblonga Kuetz 97 22 Navicula pennata A. S 96 23 Navicula pygmaea Kuetz 94 24 Navicula humilis Donk. . 96 DlATOMACE^E OF PHILADELPHIA PLATE 27 it 1 AD NATUR. DELIN. C. S. BOYEB PLATE 28 FIG. PAGE PINNULARIA 1 Pinnularia nobilis Ehr 103 2 Pinnularia major var. pulchella n. var 102 3 Pinnularia dactylus Ehr 103 4 Pinnularia major (Kuetz.) Wm. Sm 102 UlATOMACEJE OF PHILADELPHIA PLATE 28 (L AD XATUIi. DKLIN*. C. S. BOYEI! PLATE 29 FIG. PAGE PINNULARIA— Continued 1 Pinnularia gentilis (Donk.) Cl 103 2 Pinnularia viridis Xitzsch 101 3 Pinnularia dactylus var. dariana (A. S.) Cl 103 4 Pinnularia viridis var. fallax Cl 104 5 Pinnularia socialis Palmer 104 6 Pinnularia sestuarii Cl 105 7 Pinnularia rectangulata (Greg.) Cl 110 8 Pinnularia trigonocephala Cl 103 9 Pinnularia major (Kuetz.) Wm. Sm. (small form near P. viridis) 102 10 Pinnularia dactylus var. demerarae Cl 103 11 Pinnularia mormonorum (Grun.) 107 12 Pinnularia brebissonii (Kuetz.) Cl 107 13 Pinnularia mesolepta Ehr 105 14 Pinnularia termes var. stauroneiformis V. H 106 15 Pinnularia molaris (Grun.) Cl 105 16 Pinnularia braunii Grun 106 17 Pinnularia termes (Ehr.) A. S 106 18 Pinnularia appendiculata (Ag.) Cl 106 19 Pinnularia microstauron (Ehr. )C1. var.? 106 20 Pinnularia subeapitata Greg 105 DlATOMACEJE OF PHILADELPHIA AD NATOR. DELIN. C. S. BOYER PLATE 30 FIG. PAGE PINNULARIA— Continued 1 Pinnularia cardinaliculus Cl 107 2 Pinnularia viridis var. fallax Cl.? (var. B., Wm. Sm.?). . 104 3 Pinnularia legumen Ehr 107 4 Pinnularia legumen var.? 107 5 Pinnularia gibba (Kuetz.) V. H 109 6 Pinnularia mesogongyla (Ehr.) Cl 109 7 Pinnularia acrospha>ria (Breb.) Cl 108 8 Pinnularia acrosphaeria var. turgidula Grun 108 9 Pinnularia tabellaria (Ehr.) Cl. var.? 110 10 Pinnularia leptosoma Grun 105 11 Pinnularia stauroptera var. interrupts Cl 110 12 Pinnularia stomatophora (Grun.) Cl 109 13 Pinnularia stauroptera (Grun.) Cl 110 14 Pinnularia parva (Ehr.) Cl. var.? 108 15-19 Pinnularia nodosa forma capitata Cl 108 16 Pinnularia subcapitata var. paucistriata Grun 105 17 Pinnularia viridis Nitzsch var 104 18 Pinnularia viridis var. caudata n. var 104 20 Pinnularia mesolepta var. stauroneiformis Grun 105 21 Pinnularia polyonca (Br£b.) Lewis 108 22 Pinnularia borealis Ehr 109 23 Pinnularia lata (Breb.) Wm. Sm 109 24 Pinnularia borealis var. scalaris (Ehr.) Cl 109 25 Pinnularia blandita n. sp 108 DlATO.MACK.K OF PHILADELPHIA PLATE 30 I I I /O I sry .2.2 n AD NATUR. DELIN. C. S. BOYEK PLATE 31 FIG. PAGE NAVICULA 1 Navicula elegans Wm. Sm 101 2 Navicula elegans var. cuspidata Cl 101 3-4 Navicula grevillei (Ag.) Cl 99 5 Navicula libellus Greg 99 6-7 Navicula palpebralis Br6b 101 8 Navicula rhyncocephala Kuetz 97 9 Navicula cryptocephala Kuetz 97 10 Navicula longa (Greg.) Ralfs 97 PINNULARIA 11 Pinnularia br6bissonii (Kuetz.) Cl 107 12 Pinnularia borealis Ehr 109 13 Pinnularia divergens var. elliptica Grun 107 EPITHEMIA 14 Epithemia turgida (Ehr.) Kuetz Ill 15-21 Epithemia argus Kuetz Ill 16 Epithemia argus var.? Ill 17 Epithemia muelleri A. S Ill 18 Epithemia zebra var. proboscidea (Kuetz.) Grun 112 19 Epithemia gibberula var. producta Grun 112 20 Epithemia musculus Kuetz 112 22 Epithemia musculus var. constricta (Breb.) V. H 112 RHOPALODIA 23 Rhopalodia gibba (Kuetz.) Mueller 112 24 Rhopalodia ventricosa (Kuetz.) Mueller 113 DlATOMACE^E Or PHILADELPHIA PLATE 31 3.0 AD NATUli. DELIN. C. S. BoYEE PLATE 32 FIG. PAGE NITZSCHIA 1 Nitzschia circumsuta (Bail.) Grun 118 2 Nitzschia plana Win. Sm 117 3 Nitzschia granulata Grun 116 4 Xitzschia navicularis (Breb.) Grun 116 5 Nitzschia panduriformis var. minor Grun 117 6 Nitzschia apiculata (Greg.) Grun 117 7 Nitzschia tabellaria Grun 119 8 Nitzschia tryblionella Hantzsch 116 10-11 Nitzschia bilobata Wm. Sm 118 12 Nitzschia litoralis var. delawarensis Grun 118 13 Nitzschia acuminata (Wm. Sm.) Grun 117 14-25 Nitzschia amphibia Grun 122 15 Nitzschia palea (Kuetz.) Wm. Sm 122 16 Nitzschia fluminensis Grun 120 17 Nitzschia obtusa var. scalpelliformis Grun 121 18 Nitzschia linearis (Ag.) Wm. Sm 122 19 Nitzschia communis Rab 122 20 Nitzschia clausii Hantzsch 121 21 Nitzschia epithemioides Grun 118 24 Nitzschia vermicularis (Kuetz.) Wm. Sm 120 HANTZSCHIA 9 Hantzschia amphioxys (Ehr.) Grun 113 22 Hantzschia marina (Donk.) Grun 114 23 Hantzschia virgata (Roper) Grun 114 JIlATOMACE^E OF PHILADELPHIA PLATE 32 11 II- (\ \1 AD NATUH. DELIX. C. S. BoYKR PLATE 33 FIG. PAGE NITZSCHIA 1 Nitzschia longissima (Breb.) Ralfs 123 2 Nitzschia intermedia Hantzsch 122 3 Nitzschia spectabilis var. americana Grun 122 4-5 Nitzschia sigmatella Greg 121 6 Nitzschia scalaris (Ehr.) Wm. Sm 119 7 Nitzschia macilenta Greg 120 8 Nitzschia insignis Greg 119 9 Nitzschia vermicularis (Kuetz.) Hantzsch 120 10 Nitzschia longissima forma parva V. H 123 11 Nitzschia reversa Wm. Sm 123 12 Nitzschia acicularis (Kuetz.) Wm. Sm 123 13-14 Nitzschia paxillifer (O. F. Mueller) Heib 119 HOMCEOCLADIA 15 Homopocladia filiformis Wm. Sm .123 DlATOMACEvE OF PHILADELPHIA PLATE 33 AD NATUR. DELIN. C. S. BOYEU PLATE 34 FIG. PAGE SURIRELLA 1 Surirella striatula Turpin 125 2 Surirella anceps Lewis 128 3 Surirella intermedia Lewis 128 4 Surirella arctissima A. S 128 5-6 Surirella delicatissima Lewis 128 7 Surirella intermedia Lewis forma minor ? 128 CYMATOPLEURA 8-9 Cymatopleura solea (Breb.) Wm. Sm 129 DlATOMACE^E OF PHILADELPHIA PLATE 34 I I m AD NATUR. DELIX. C. S. BOYER PLATE 35 FIG. PAGE 8URIRELLA 1 Surirella fastuosa Ehr 127 2 Surirella biseriata (Ehr.) Breb 124 3 Surirella splendida (Ehr.) Kuetz 125 4 Surirella crumena Br6b 126 5 Surirella ovalis Breb 126 6 Surirella tenera Greg 125 7 Surirella recedens A. S 127 8 Surirella linearis Wm. Sm 124 9 Surirella oblonga Ehr.? 127 10 Surirella cruciata A. S 127 1 1 Surirella gracilis Grun 127 12-13 Surirella amphioxys Wm. Sm 124 IMATOMACEJJ OF PHILADELPHIA PLATE 35 7 \S 8 AD XATUli. DEUX. 0. S. BOYER PLATE 36 FIG. PAGE SURIRELLA— Continued 1 Surirella elegans Ehr 125 2 Surirella robusta Ehr 124. 3 Surirella febigerii Lewis 128 4 Surirella gemma Ehr 125 5 Surirella guatimalensis Ehr 126 6 Surirella pandurifonnis Win. Sm 126 7-9 Surirella pinnata Wm. Sm 126 8 Surirella angusta Kuetz 127 DlATOMACE-E OF PHILADELPHIA PLATE 36 ^__D Q- J) U c L n (C AP XATUR. DELTX. C'. S. BOYER PLATE 37 FIG. PAGE CYMATOPLEURA 1 Cymatopleura elliptica (Breb.) Wm. Sm 129 2 Cymatopleura elliptica forma spiralis 129 3-4 Cymatopleura marina Lewis 129 CAMPYLODISCUS 5 Campylodiscus hibernicus Ehr 130 6 Campylodiscus echeneis Ehr 130 OF PlIILADKI.I'l 1 1 A PLATE 37 ^y^//^^K^ , mmesm*' AD XATI'lt. DKI.IX. ('. S. l^OYKI! PLATE 38 FIG. PAGE 1 Amphora gigantea var. fusca A. S 65 2 Meloseira crenulata (Ehr.) Kuetz 15 3-4 Licmophora baileyi (Edw.) Grun 40 5 Coscinodiscus polyacanthus Grun 22 6-7 Ditylum intrioatum (West) Grun 30 8 Pyxidicula cruciata Ehr 19 9 Gyrosigma scalproides (Rab.) Cl 76 10 Coscinodiscus asteromphalus var. omphalantha (Ehr.) Grun 23 11 Khabdonema minutum Kuetz 36 12 Gyrosigma kuetzingii (Grun.) Cl 76 13 Gyrosigma prolongatum (Wm. Sm.) Cl 76 14 Cymbella parva (Wm. Sm.) Cl 61 15 Gomphoneis herculaneum (Ehr.) Cl. (zone view) 70 16 Cymbella ventricosa Kuetz 62 17-18 Eunotia sp. (abnormal ?) 54 DlATO.MACK.E OF PHILADELPHIA PLATE 38 AD XATL'li. DELIX. C. S. BOYER PLATE :«> FIG. PAGE 1 Nitzschia speotabiUs var. americana Grun. (zone view) .. 122 2 Nitzschia paiuluriformis Greg 117 3 Hantzschia amphioxys (Ehr.) Grun 113 4 Hantzschia amphioxys var. major Grim 114 5 Nitzschia dubia Wm. Sm 118 6 Nitzschia amphioxys Wm. Sm 114 7 Nitzschia compressa (Bail.) 116 8 Nitzschia compressa var. minor H. L. Smith 116 9 Surirella intermedia Lewis (zone view) 128 10 Surirella arctissima A. S. forma minor 128 1 1 Surirella ovalis Breb 126 12 Surirella biseriata (Ehr.) Breb 124 13 Nitzschia sigma (Kuetz.) Wm. Sm. .• 121 14 Nitzschia obtusa var. flexella H. L. Smith 121 15 Stauroneis legumen Ehr 89 16 Nitzschia obtusa Win. Sm . .. . 121 DlATO.MACE-K OF PHILADELPHIA PLATE 3!) >ooooo o ooocoo OOOOOO OOOOOOOC O OOOOOOOOOOOOO 1 OOOO OOOOOO OOO C OOOOOO OOOOOOOC* OOOOOOOOOOOOO OOOOOOOOOOOOOO (OOOOOO OOOO Ooc J OO OO OOOOOO ooooooooooo OOOO OOOO OOOO OOOO OOOOOOi , OO O O OOOO O - oo oo o o c OOOOOOo 1000°°°/ e /o 75- AD XATUli. DliLIN. C. S. BOYEU '.. PLATE 40 FIG. PAGE 1 Caloneis liter (Win. Sm.) Cl 81 2 Anomoeoneis sphserophora (Kuetz.) Cl 80 3 Nitzschia spathulata Breb ' 120 4 Stauroneis ? abnormal 89 5 Xavicula ? abnormal 101 6 Podocystis adriatica Kuetz 129 7 Xitzschia dissipata (Kuetz.) Grim 120 8 Cymbella ventricosa Kuetz. (zone view) 62 9 Navicula radiosa Kuetz. (zone view) 94 10 Detail of Rhabdonema arcuatum (Lyng.) Kuetz 35 11 Diatoma anceps (Ehr.) Kirchn. (containing chromatc- phores) 42 12 Coscinodiscus asteromphalus Ehr. (trans, section, after Pelletan) , 23 13-14-15 Transverse section (diagram) of Pinnularia showing straight, oblique and grooved raphes 101 16 Transverse section (diagram) of Biddulphia favus show- ing inner punctate stratum (after Deby) 31 17 Transverse (ideal) section of Surirella 124 18-19 Transverse (ideal) section of Pinnularia, before and after division 101 20 Transverse section of Nitzschia linearis (Ag.) Wm. Sm. . 122 21 Transverse section (diagram) of Xavicula 89 22 Transverse section (diagram) of Cymbella 60 23 Transverse section (diagram) of Amphora 65 DlATOMACE^E OF PHILADELPHIA PLATE 40 K, I « -0 : o :0 o 0- -- o- : o- o o o -O 0- o; - o o :o* to o '- 0 - o: o: :0 :o o< -oo- -00 0 0 i 0- o- 0: 300000000 OOOQOO joooooooo QQOOOOOO 10 (Tj : i ' n /a. n 0 © cj.3 AD XATUR. DELIN. C. S. BOYER ;.>.