Greville^ on New Diatoms. 
85 
no undulating line in the border. Distance between the 
angles -0029". (Fig. 11.) 
Hab. Barbadoes deposit ; excessively rare. 
A fine species, coming nearest to T. Abercrombieanum, but 
wanting the undulating border line. The fork referred to in 
the specific characters here assumes a Pater a~\\\Q form. 
Whether any dependence can be placed on the two little 
spurs at the base of the pseudo -nodule, a character I have 
not observed in any other species of the group,, it is impossible 
at present to say. The puncta are numerous. 
Triceratium gratiosum, n. sp., Grev. — Valve with slightly 
convex sides, obtuse angles, and striated margin; centre a 
triangular, blank space; border divided by transverse costse 
into closely punctated compartments ; a short line from each 
angle of the inner triangle terminating in a fork, from the 
centre of which spring two other lines, curving outwards to 
the margin. Distance between the angles, -0029" to "0035". 
(Figs. 12, 13.) 
Hab. Barbadoes deposit ; extremely rare ; George Norman, 
Esq., Dr, Greville. 
A very elegant species, closely and conspicuously punctate. 
The arrangement of the vein-like lines at the angles is pecu- 
liar, and serves at once to distinguish it from all its allies. 
Two lines spring from a point within the fork already men- 
tioned, near its base, and curve gracefully outward until they 
reach the margin. In the examples which I have examined, 
the lateral costse alternate more or less regularly with im- 
perfect ones, extending about half-way across the border. 
Triceratium variegatum, n. sp., Grev. — Valve with straight 
sides, obtuse angles, and striated margin ; centre a blank, 
triangular space; border divided by transverse costse into 
very minutely punctated compartments; a short line from 
each angle of the central triangle terminating in a deep, 
campanulate fork, the lines of which reach the margin. 
Distance between the angles, '0027". (Fig. 14.) 
Hab. Barbadoes deposit; excessively rare; George Nor- 
man, Esq. 
Of this beautiful diatom I have seen only a single specimen ; 
but it differs so materially from all the preceding, that no 
doubt whatever can exist regarding its claim to being ranked 
as a distinct species. It will be recognised at once by the 
graceful campanulate or vase-like compartment at each 
angle of the valve, which is very minutely, yet more dis- 
tinctly punctate than the border. A very minute, deflexed 
line may also be seen given off externally on each side from 
near the base of this compartment. 
