Greville_, on New Diatoms. 
41 
A very small species compared with the preceding^ but 
evidently closely allied to it^ the prominent character of the 
scattered central puncta being distinctly exhibited in Ehren- 
berg^s rude figure. The small number of rays at once 
separates it from all the others. 
Stictodiscus Johnsonianus, n. sp., Grev. — Pore-like puncta 
of each compartment equal, forming a short linear series; 
rays 50; diameter '0034/'. (PI. IV, fig. 3.) 
Hab. Deposit at South Naparima_, Trinidad; Christopher 
Johnson, Esq. 
Not less beautiful than Stictodiscus Buryanus, and well 
distinguished by the single series of puncta in each compart- 
ment, which extends from the margin to about a third of the 
distance between it and the centre. Other puncta are scattered 
over the surface of the disc, as in the two previous species. A 
single example only has been found, for the possession of 
which I have again to acknowledge the kindness of Mrs. 
Bury. 
Stictodiscus insignis, n. sp., Grev. — Cellules large at the 
margin, forming a moniliform series in each compartment to 
near the centre; rays 46; diameter '0021". (PI. IV, fig. 4.) 
Hab. Barbadoes deposit ; very rare. 
A small but exquisite diatom, of which I have as yet only 
seen two individuals. It will be at once recognised by the 
puncta, or in this instance rather cellules, which, commencing 
at the margin, continue in a moniliform series, and de- 
creasing gradually in size until they approach the centre, 
when they lose their radiating character and occupy the entire 
surface. 
In this species we do not find the peculiar puncta scattered 
over the central portion of the disc, so characteristic of the 
three preceding species, while the centre itself is fully occu- 
pied vrith puncta or minute cellules similar to those of the 
compartments. The valve is also much less convex. 
Stictodiscus dives (Ehr.), Grev. — Pore-like puncta in each 
compartment minute, equal, forming a single series ; rays 52 
(centre minutely punctate ?). 
Discoplea? dives, Ehr. 
Actifioptychus dives, W^Y. 'Microgeol,' PI. xix, fig. 12; Ralfs 
in Pritch, ' Infus.' 4th ed., p. 840. 
Cyclotella dives, Kiitz., ' Sp. Alg.,^ p. 20. 
Hab. Egina. 
The appearance of this disc, as far as we can judge from 
Ehrenberg's figure, is sufficiently striking to justify its pro- 
visional admission into the genus. No central punctation, 
however, is exhibited in the figure. 
VOL. 1. NEW SER. d 
