40 
Greville^ on New Diatoms. 
situated. The extent of the deposit is not known ; but^ like 
that in Barbadoes_, it is probably large both in surface and 
depth. It does not contain a great variety of diatomaceous 
forms ; but various new and interesting species have already 
been observed in it. 
Stictodiscus Buryanus, n. sp., Grev. — Pore-like puncta at 
the marginal extremity of each compartment, forming a 
pyramidal group; rays 30; diameter '0040" (PI. IV, fig. 1). 
Hab. Deposit at South Naparima, Trinidad ; Mrs. Bury. 
The disc of this superlatively beautiful diatom is trans- 
parent and gently convex, remotely dotted over with large, 
clear, pore-like puncta, exhibiting also the shadows of puncta 
belonging to the lower valve. The marginal groups consist 
of six or seven. The radiating lines (septa?) are free for more 
than half their length, and then, after anastomosing, become 
faint and inconspicuous before reaching the centre. When 
these lines are accurately focussed, the plicate character of 
the disc is not visible, but by changing the focus it becomes 
conspicuous (fig. 2). A single specimen only has hitherto 
been observed, for which my cabinet is indebted to the 
generous kindness of its discoverer. 
Stictodiscus Bota (Ehr.), Grev. — ^' Disco amplo superficie 
insequaliter papillosa, ]^apillis centralibus majoribus, margine 
radiis 52 sequalibus centrum non attingentibus intervallorum 
papillis sparsis.^' 
Discoplea? Bota, Ehr., ^Bericht. Berl. Akad.,' 1844, p. 202 ; 
^ Microgeol.,^ pi. xxxv, a. 22, fig. 6. 
Cyclotella Bota, Kiitz., ' Sp. Alg./ p. 19; Balfs in Pritch. 
' Infus.,' 4th edit., p. 812. 
Hab. Southern Ocean. 
The figure given of this diatom, by Ehrenberg, indicates 
very clearly that it is a genuine Stictodiscus. The valve is 
very large, the radiating lines much shorter than in the other 
species ; the puncta within the compartments disposed, appa- 
rently, in an irregular double series, and extend as far as the 
termination of the lines. The whole central space is covered 
with numerous large puncta, as in the preceding species. 
Stictodiscus Botula (Ehr.), Grev. — Puncta equal, remotely 
scattered over the blank centre of the disc, those within the 
compartments irregularly (?) disposed ; rays 20. 
Discoplea? Botula, E^hr., ' Microgeol.,' pi. xxxv, a. 22, 
fig. 7. 
Cyclotella Botula, Kiitz., 'Sp. Alg.,^ p. 19; Kalfs in Pritch. 
' Infus.,' 4th edit., p. 840. 
Hab. Southern Ocean. 
