Diatomaceae of Philadelphia/Biddulphioideae



(a) Triceratiinæ.—Frustule cylindrical or prismatic, with three or more sides.

(b) Biddulphiinæ.—Frustule cylindroid; valve with ends elevated into round processes or long horns.

(c) Anauleæ.—Valve elliptical, lunate or triangular, with internal septa.

(d) Euodieæ.—Frustule cuneate in zone view; valve lunate.


(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.


Valve with the angles separated from the central part by lines imitating septa. Surface 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 distinguished 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.


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.

Pl. 6, Fig. 9.


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 subcircular, convex, more or less elevated at the angles into processes or horns. Markings cellular or punctate. Chromatophores, small plates of various forms.


Valves costate biddulphiana
Valves not costate:
Markings cellular, angles elevated into horns favus
Markings cellular, 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
processes truncate, valve orbicular lævis
processes absent, valve divided by irregular lines alternans
not so divided reticulum


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 in longitudinal 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.


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 transverse section of a portion of the valve showing the cellular structure and the punctated lower stratum.


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.

Pl. 6, Fig. 3.

A cruciform variety occurs at Pensauken, N. J., artesian well (Coll. F. J. Keeley).


Valve elliptical-lanceolate, convex, with diagonal rows of puncta 12 in 10 µ and sometimes 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. Connective 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 common.

Pl. 7, Fig. 6.


Valve rhomboidal, sometimes triangular, with subconical processes. Surface convex with hexagonal reticulations, 7-9 in 10 µ, irregular at the centre and radiating to the circumference. 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.

Pl. 7, Fig. 5 (somewhat inclined, as usually seen).


Valve orbicular, convex, with reticulations 5 in 10 µ 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 µ in longitudinal rows.

Cerataulus smithii Ralfs.

Eupodiscus radiatus Wm. Sm.

Blue clay. Along the coast southward.

Pl. 7, Fig. 8.


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.

Pl. 7, Fig. 7.


Valve suborbicular or triangular, with short, truncate processes. Surface with fine puncta about 13 in 10 µ 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 in size.

Blue clay. Common along the coast.

Pl. 7, Fig. 9.

Fig. 10 (magnification about 260 diameters only) illustrates sporangial frustules discovered 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.


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 costæ extend inward from the border in various directions. Angles with small puncta in transverse and longitudinal rows.

Triceratium alternans Bail.

Blue clay. Along the coast.

Pl. 6, Fig. 7 and probably Fig. 8.


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.

Pl. 6, Fig. 5.


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.


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.

Pl. 7, Fig. 11, and Pl. 10, Fig. 15.

I am unable to distinguish between E. læve and E. debile, as intermediate forms occur.

Terpsinoë Ehr.

(terpsinoos, gladdening?)

Frustules quadrangular, adnate in filaments, usually free. Valve elliptical or triangular, with undulating sides divided by septa into three or more sections.


Valve lobed at each end or angle. Central space rounded, hyaline. Surface with fine puncta in radiating lines.

Blue clay. Not common.

Pl. 6, Fig. 10.


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 µ.

Pleistocene clay at Buckshutem, N. J. Fossil at Wildwood, N. J.

T. americana, forma trigona Pant.? (Le Diatomiste, Vol. 2, p. 207.)

Pl. 6, Fig. 11.


Euodia Bail. (1860)

(derivation uncertain; apparently from euodia, fragrant, probably a euphemism)

Frustule in zone view cuneate. Valve semi-lunate, coscinodiscoid.


Valve with rounded markings, larger and scattered at the centre, radiating at the circumference and in indefinite straight rows at the semi-radius.

Delaware Bay (Mann).

Pl. 5, Fig. 1.

I have not seen this in the Philadelphia material. The figure is drawn from a specimen from the Gulf Stream, S. Atlantic.