The Diatomaceæ of Philadelphia and Vicinity — John Shaqi
The Diatomaceæ of Philadelphia and VicinityBoyer, Charles S. (Charles Sumner)
Science
The Diatomaceæ of Philadelphia and Vicinity
Boyer, Charles S. (Charles Sumner)
Diatoms -- Pennsylvania -- Philadelphia
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 striæ. 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.
{23}COSCINODISCUS RADIATUS 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.
Pl. 3, Fig. 11. Fig. 1 is probably a smaller form.
COSCINODISCUS SUBAULACODISCOIDALIS 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 papillæ, 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 2½ in 10 µ, 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 papillæ, 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}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 striæ.
Great Sedge Island, N. J. (artesian well), and in outcrops later than the
Miocene, where it is usually found.
Pl. 3, Fig. 5.
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