GrevillEj on Neiv Diatoms. 
9 
Hab. Monterey deposit; cabinet of L. Hardman_, Esq. 
Allied to T. tesselatum and robustiim, and more nearly to 
T, obtusiim of Ehrenbergj but tbat close observer would 
scarcely have omitted in bis figure of the latter species the 
crowded puncta in the angles of the Monterey diatom. Never- 
theless I think it right to quote it as a doubtful synonym. 
Triceratium didce, n. sp.^ Grev. — Small ; valve with slightly 
convex sides and subacute angles_, the margin with oblong 
striae ; surface depressed^ with radiating lines of remote 
punctiform granules ; angles raised^ and tilled with minute 
puncta. Distance between the angles '0030."' (I'ig- 20.) 
Hab. Barbadoes deposit_, Cambridge estate ; in slides com- 
municated by C. Johnson_, Esq. ; very rare. 
A very elegant species^ of which but few examples have 
occurred. It is remarkable for its depressed surface^ so that 
when the angles are in focus the central puncta are scarcely 
perceptible. The angles do not appear to be very prominent, 
but are so abruptly elevated that the vertical view of the side 
might be taken at first sight for a transverse line. The central 
puncta are minute, faint, and remote, becoming a little 
larger towards the margin. The latter is rather broad, and 
marked with elegant, oblong striae, 8 in -001"^ 
Triceratium mammosum, n. sp., Grev. — Minute, with 
thick, produced, rounded angles, filled with minute puncta 
and straight sides (reckoning from the base of the angles) ; 
the central space hexagonal, marked with remote and scat- 
tered puncta. Distance between the angles 'OOIS'". (Fig. 19.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. ; extremely rare. 
Very conspicuous at a glance, from the large, produced, 
mammseform, hemispherically rounded angles, which, being 
covered with puncta, appear out of all proportion to the rest 
of the valve. Central puncta circular, irregularly scattered. 
Amphitetras. 
Amphitetras elegans, n. sp., Grev. — Small ; valve with the 
sides slightly concave in the middle ; angles rounded, termi- 
nating in a small, ring-like pseudo-opening; cellulationminute, 
radiating from the depressed centre, somewhat smaller and 
more crowded within the angles. Distance between the 
angles -0025. (Fig. 24.) 
Hab. Monterey deposit ; L. Hardman, Esq. 
A most beautiful small species, elegantly radiate, with a 
very narroAv simple margin. The pseudo-openings have the 
appearance of being the ends of short hyaline tubes. 
