attached to Hypnum. And it is the only gathering hitherto made, so far as I am aware. It can hardly be considered other than an extreme variety of M. circulare, with the strongly marked pervious costæ of this species in s. v., and the consequent crenulation or intra-marginal punctation of the valves in f. v., nearly obliterated, approaching indeed the smoothness of Licmophora. The discovery of this intermediate form was the more interesting, as it enabled me to place Greville's and Arnott's Peronia erinacea where it belongs. This singular form, which was at first considered as a Gomphonema, and subsequently made the type of a new Genus, of which it is the sole species, is now related to M. intermedium, as the latter is to M. circulare, in other words it is a smooth form of Meridion, and of course the connecting link with Licmophora, all the species of which hitherto enumerated are marine. M. intermedium is No. 238, and M. erinaceum (Gomphonema fibula Peronia erinacea) is No. 239 of my "Species Typicae Diatomacearum." Navicula Kutzingiana, n. sp. H. L. S. Avranches, Normandy, France. M. de Brébisson. Frustules linear, valves scarcely inflated, with rounded ends, and three or four conspicuous striae radiating from the central nodule, and which are prominent also, along with the central nodule, in f. v. Frustules in f. v. quadrangular, frequently adhering and forming a short filament (Diadesmis), and with two distinct intra-marginal (bead-like) vittae, at either end. Length .0006 to .00085; breadth, f. v. .00033, S. v. .00021. Striæ about 50 in .001. Plate III, fig. 3.

This small, but distinct form, which from the coherence of the frustules into short filaments might almost be termed a Diadesmis, I received from M. de Brébisson labeled "Amphiprora arenaria." A glance at the figure I have given will show that it does not belong to the genus Amphiprora as now limited, but that it is a true Navicula. As there is already a Nav. arenaria, I give to it the name of the celebrated Algologist, Kutzing, whose numerous figures of Diatomaceæ, though but mere outlines, sketched by aid of a microscope, that would scarcely be looked at, much less through, at the present day, possess more of the character and catch more of the spirit of the living species, than many of the representations of modern days, and whose descriptions are models of accuracy and conciseness. The more I study his plates the more I admire their

conscientious accuracy and faithfulness. Grunow has described a Navicula Kutzingii, but it proves to be N. Proserpinae (Diploneis) E. thus leaving the name free. It is No. 287 of the "Species Typicæ Diatomacearum."

Navicula parvula, n. sp. H. L. S. Villerville, France. M. de Brébisson. Frustules small, valves lanceolate, with acute apices. Striæ divergent and readily seen. Frustules linear in f. v. with rounded ends. Length .0005; breadth .00015. Striæ 42 in Plate III, fig. 4.

'100'

I have not been able satisfactorily to identify this form as belonging to any species hitherto described. It is extremely abundant in the gathering which I received from M. de Brébisson, labeled by him simply as "Navicula," indicating that he was not decided as to the species.

Nitszchia Kittoni, n. sp. H. L. S. Hab. River Catuche, Caracas, Venezuela. Mr. F. Kitton. Frustules linear, valves lanceolate with sharp and slightly constricted apices, marginal punctæ very distinct, 16 in .001, and quite prominent in f. v., striæ faint. Length .0007 to .001; breadth .0002. Plate III, fig 5.

Mr. Kitton, when he sent this diatom to me, referred it very doubtfully to W. Smith's Nitzschia minutissima, to the figure of which it has a remote resemblance, the apices, however, are less constricted, and Smith himself quotes Synedra dissipata of Kutzing as a synonym, from specimens sent to him by De Brébisson, and as I have from De Brébisson, specimens labeled “Nitz. minutissima W. S.= Synedra dissipata," which are quite distinct from the present form, and with the marginal punctæ much finer, 39 in .001, and not so prominent in s. v., I have not hesitated to name it after the eminent diatomist from whom I received it. It was collected from a water tank supplied by the river Catuche.

Raphoneis australis, n. sp. H. L. S. Hab. Royal Sound, Kergueland's Land. Dr. J. H. Kidder. Frustules somewhat variable in size, valves cuneate, rounded at the larger end, and coarsely monliform striate, striæ interrupted by a smooth blank space, frustules slightly cuneate in f. v. Length .0005 to .00086; breadth .00022 to .0004. Striæ about 30 in .001. Plate III, fig. 6.

This form constituted the bulk of a washing from black sand dredged by Dr. J. H. Kidder, Surgeon U. S. N., in from five to twelve fathoms water in Royal Sound, Kergueland's Land,

January, 1875, on occasion of the visit of the American party to observe the transit of Venus. Only two dredgings were made, and they were almost identical. Plagiogramma Robertsianum of Greville, was also abundant, and a small and doubtfully new Surirella. Besides these, there were a few larger diatoms, and especially a variety of Auliscus coelatus, and as the dredging continued fragments of Hypnum, Bartramia, and Barbula, washed off from the land, these explain the occurrence of a few fresh water forms; no Foraminifera were found, but spines of Hemiaster caudatus were abundant. It is but justice to add, that Dr. Kidder, who was the Botanist of the expedition, and was therefore mainly employed in collecting the land plants, was prevented from making other dredgings and collections of Diatomacea, by the sudden and unexpected recall of the party, which is the more to be regretted since the only dredgings that were made have proved so fruitful; and as so little is known of the Diatomacea of high southern latitudes.

Rhizosolenia Eriensis, n. sp. H. L. S. Hab. Buffalo, N. Y., Lake Erie, D. S. Kellicot, Esq.; Cleveland, Ohio, Lake Erie, H. C. Gaylord, Esq.; Lake Michigan, Chicago, S. A. Briggs, Esq. Frustules of medium size, compressed and somewhat flattened; six to twelve times as long as broad; annuli on the dry frustules conspicuous, altenate, and with a zig-zag median connection, valves finely striate, bristles nearly or quite as long as the frustules, and with the calyptra excentric, lying nearly in a line with one margin of the frustule when the flat side is in view. Length of frustules .003 to .006. Plate III, fig. 7.

This remarkable diatom, the only fresh water species of Rhizosolenia hitherto known, was first sent to me living by Mr. H. C. Gaylord, of Cleveland, O., who obtained it in a filtering of Lake Erie water, used for the supply of the city. The bulk of the collection was Stephanodiscus Niagarae, which is almost always obtained in such filterings; subsequently Mr. Briggs, then Editor of "The Lens," detected it in filterings from Lake Michigan, and I furnished him a description which he published in his list of "Diatomaceæ of Lake Michigan," in Volume I. of "The Lens," page 44. It was, however, a rare form, until Mr. D. S. Kellicot, of Buffalo, by making filterings at different seasons of the year, finally obtained it in considerable abundance. Many of the fresh water forms procured in these filterings are considerably modified, e. g Tabellaria fenestrata

is quite twisted, and also the variety of Fragilaria capucina, (if it be a variety of this diatom) known as F. Crotonensis, and also some of the Synedra, Does this, when taken in connection with the occurrence of Rhizosolenia, and an Actinocyclus, to be described presently, indicate that salt or brackish water is to be found at the bottom of the great Lakes, in which these diatoms live, or by which they are modified? It is well known that the late Mr. Stimpson, in connection with Dr. Hoy, of Racine, and others, dredged in some sixty-four fathoms, from the bottom of Lake Michigan, a marine crustacean of the genus Mysis, and other forms of a decidedly arctic type; whence it has been inferred that the great Lakes formerly had communication not only with the Atlantic through the St. Lawrence, but with the Arctic Ocean through Hudson's Bay. Although the Rhizosolenieae have been found in tropical waters, they are far more abundant in those of high latitudes. R. Eriensis has never been found as a littoral form, and is only known from filterings of water taken at a great distance from the shore, and from a considerable depth.

Cestodiscus Baileyi, n. sp. H. L. S. Hab. Lower Lake Klamath. Lt. Williamson. Disc circular, diam. .0025 to .0028, inflated, and with distinct radiating granules; and showing more or less the characteristic subulate blank spaces of Actinocyclus; without umbilicus; processes intra-marginal, small, and numerous; the punctæ near the margin of the valve are in parallel rows, 27 in .001. Secondary plate or septum, with a large central opening, fringed with somewhat irregular rays, which do not reach the margin. Plate III, fig. 8.

This species constituted the larger portion of one of the "Infusorial Marls" from the neighborhood of Lost River, Lower Klamath Lake, Oregon, and was collected by Lt. Williamson, as noticed in Volume VI, "Reports of Pacific R. R. Explorations." I am not sure that this diatom belongs to Greville's genus Cestodiscus (or even that the genus itself is a good one); the intra-marginal processes, not connected by a furrow, or distinct line, would seem to place it here, but it has, on the other hand, many affinities with Melosira. Provisionally, I place it in Greville's genus, and name it after the distinguished microscopist from whom I received the material, and whose notice of these infusorial earths was received too late for insertion in

the government reports. The deposit is fluiviatile, recent tertiary.

Amphora mucronata, n. sp. H. L. S. Hab. Atlantic Marshes, Cape May, N. J., F. W. Lewis, M. D. Frustules in f. v. broadly oval, dorsum with distant longitudinal lines, ventral surface with indistinct longitudinal lines, or furrows, central nodule elongated and pointed (mucronate), and touching the margin of the connecting zone, which is of variable breadth, nodules at the end quite small. Median line strongly and sharply inflected and minutely punctate along its whole length, an irregular row of minute lines or elongated dots on the valve within the margin. In s. v. dorsum very convex; ventral margin straight, or nearly so, with slight constriction at the ends; central nodule indistinctly shown (out of focus). Striæ excessively miLength .0026; breadth .0012 to .002. Plate III, fig. 9.

nute.

I received the gathering containing this very pretty diatom many years ago from Dr. Lewis, and I had entirely forgotten a pencil sketch which he had sent to me at the same time, when I issued it as No. 38 of the "Species Typicæ Diatomacearum," under the name of A. mucronata. I regret that I did not name it after the discoverer, who, doubtless, would have described it, if he could have continued his excellent studies of the diatomaceæ. It has a close resemblance to Amphiprora hyalina of Dr. Greville, described in his paper on Hong Kong diatoms in "Ann. and Mag. Nat. Hist., July, 1865," though his figure does not show the peculiar mucronate central nodule. The present species is not an Amphiprora, and, therefore, if it be Dr. Greville's form, which is not unlikely, his specific name must be changed, as there is already an Amphora hyalina. It belongs to the so-called "Complex Amphorae" of Gregory, and like A. Complexa it is very tender, scarcely standing strong acid treatment, or even continued burning at a red heat, without injury.

Actinocyclus Niagarae, n. sp. H. L. S. Hab. Lake Erie, Cleveland, O. H. C. Gaylord, Esq. Disc large, diam. .0038, valves very much inflated and densely packed with minute radiating punctæ, which are scattered loosely and irregularly at the centre, and sometimes radiate from two central blank spaces. In the living form, the connecting membrane is broad, and the highly inflated valves cause it to lie obliquely. There is a characteristic circlet of minute spines, within the margin of