Greville, on New Diatoms. 
3 
times occupy two thirds of the radius. The substance appears 
to be fragile. 
COSCINODISCUS. 
Coscinodiscus eleganSj n. sp.^ Grev. — Disc small, with a 
smooth irregular umbilicus; granules rather large, equal, in 
radiating, not very close lines, which terminate in a narrow 
belt of minute crowded puncta ; border strong, finely striate. 
Diameter about -0030". (Fig. 6.) 
Hab. Monterey deposit; Laurence Hardman, Esq.; R. K. G. 
Allied, apparently, to C. Lutkb and gemmifer of Ehren- 
berg, having, in common with those species, a smooth um- 
bilicus and a narrow belt of minute puncta between the 
termination of the radiating lines and the border ; but dif- 
fering from both in the strong, finely striated border, which 
appears double in consequence of a fine dividing line. The 
narrow punctate belt is scarcely so broad as the border. 
Granules large, circular, conspicuous, about 8 in '001"' in the 
radiating lines. 
Coscinodiscus pulchellus, n. sp., Grev. — Large; valve con- 
vex, largely reticulate ; cellules hexagonal, somewhat smaller 
near the margin, the last row more or less oblong ; border 
strong, rather broad, with strong, subremote strise. Diameter 
about -0050'^ (Fig. 7.) 
Hab. Barbadoes deposit, Cambridge estate ; C. Johnson, 
Esq. 
A fine species, with a regular, somewhat delicate hexagonal 
cellulation, which becomes smaller only near the margin, 
the cellules of the last row being not wider, but only longer. 
The strong striae of the border pass for a short distance into 
these oblong cellules. 
Coscinodiscus robustus, n. sp., Grev. — Large; disc convex, 
cellulate; cellules large, roundish-hexagonal in the middle, 
becoming smaller, rounder, and more remote towards the 
margin ; border very strong, broad, elevated, with irregular 
striae. Diameter '0045'^ to '0055.^' (Fig. 8.) 
Hab. Monterey deposit ; cabinet of L. Hardman, Esq. 
A rather singular species, strong and robust in its general 
aspect with a broad elevated rim. The cellulation is coarse, 
and the hexagonal spaces are continued nearly equal in size 
to the margin ; but the cellules themselves have a roundish 
appearance, large in the central region, then becoming gra- 
dually smaller as they approach the margin. The walls, of 
course, become correspondingly thicker, until at length the 
cellules look like mere circular perforations in the middle of 
