GREVILLE, ON NEW DIATOMS. 233 
Hab. Barbadoes deposit, from Cambridge estate; C. 
Johnson, Esq. 
I do not know any described species to which this diatom 
can be referred. The central remotely scattered puncta are 
rather large, while those near the margin are minute. There 
is no pseudo-nodule. 
Triceratium lineolatum, n. sp., Grev.—Valve with nearly 
straight sides, somewhat obtuse angles, and prominent pseudo- 
nodules ; surface entirely filled with minute, uniform, radiating 
cellules, while 4—5 short vein-like lines project inwards 
from the sides. Breadth between the angles about 0042”. 
(Fig. 16.) 
Hab. Barbadoes deposit, from Cambridge estate; C. 
Johnson, Esq. 
Quite distinct from every species in this large genus. The 
vein-like lines are generally four on each side, and reach 
scarcely half way to the centre. Although the structure is 
minute, it is evidently cellulate under a power of 300 or 
400 diameters. 
Triceratium lobatum, n. sp., Grev.—Small ; valve distinctly 
3-lobed, with no perceptible pseudo-nodules; lobes ovate, 
having about 4 short vein-like lines on each side, and being 
more or less filled up with scattered puncta. Distance be- 
tween the angles about 0022”. (Fig. 13.) 
A very beautiful and well-marked little species. The 
peculiar form is constant, resembling a 3-lobed leaf, while 
the short parallel lines may be compared to the veins. The 
puncta are not equally visible in all specimens, being some- 
times irregularly scattered and most conspicuous near the 
margin; but in perfect examples the puncta (which, in fact, 
constitute a regular cellulation) are equally distributed over 
the valve, except in the centre, where there is a partially 
blank triangular space. 
Triceratium denticulatum, n. sp., Grev.—Valve with con- 
cave sides and rounded angles; margin with numerous short, 
tooth-like striz, the middle with a few minute puncta ar- 
ranged in a triangular form, leaving the centre blank; to- 
wards the angles a few scattered large puncta. Distance 
between the angles -0025”. (Fig. 14.) 
Hab. Barbadoes deposit, from Cambridge estate; C. 
Johnson, Esq. 
In general form the frustule may be said to be slightly 3- 
lobed. The marginal strize are very short and rather robust, 
forming an even line, except quite at the angles, which are 
left blank, but there is no pseudo-nodule. 
Triceratium constans, n. sp., Grev.—Valve with straight 
