GrevillE; on New Diatoms. 
75 
circular space, minutely punctate. Distance between the 
angles -0026". (Fig. 4.) 
Hab. Barbadoes deposit ; excessively rare. 
In general outline this species bears a close resemblance to 
T. productum of my Series II, but differs essentially in the 
absence of all vein-like lines. From T» capitatum of Ralfs it is 
removed by the much larger size, shorter angles, the absence 
of spines, and by the minute and close punctation of the 
whole surface. 
Triceratium insignis, n. sp., Grev. — Large. Valve with con- 
cave sides, and broadly rounded angles, furnished with 
minutely punctate pseudo-nodules ; surface filled with radiat- 
ing lines of minute, distinct granules, except a small, central, 
blank space ; margin with short, broad strise, 9 in -001". Dis- 
tance between the angles -0034. (Fig. 5.) 
Hab. Barbadoes deposit ; excessively rare. 
A remarkably fine and ornate species, possessing most dis- 
tinctive characters. At first sight the angles have the appear- 
ance of being separated from the centre by a transverse line, 
but this is not the case. The efifect is produced by the radiat- 
ing lines of granules curving up the prominent angles, and 
being viewed, as it were, in prospective, the extremities of the 
lines form a transverse row of dark points. A very con- 
spicuous feature in the valve is the termination of what are 
doubtless strong, broad strise in the front view, and which are 
curved over the edge of the valve in the side view. The ra- 
diating lines of granules which closely cover the surface do 
not quite reach the margin, but leave a narrow, blank space. 
Triceratium rotundatum, n. sp., Grev. — Small. Valve with 
deeply concave sides and broadly rounded angles, the ends of 
which are filled with minute puncta, bordered with a few 
larger ones; centre blank, surrounded by an irregular, tri- 
angular band of still larger granules, between which and the 
granules of the angles is a transverse, blank space ; concave 
margins, with a few distant, large granules. Distance between 
the angles -0020". (Fig. 6.) 
Hab. Barbadoes deposit; extremely rare. 
About the size of T. castellatum and T. Westianum ; but 
the angles do not form segments of circles as in those species, 
being merely broadly rounded. About six granules compose 
the marginal row in the concavities of the valve. 
Triceratium amo^num, n. sp., Grev. — Small. Valve with 
straight sides and rounded, incrassated angles ; centre some- 
what convex, with subremote radiating puncta, which gradu- 
ally increase in size from the centre to the circumference, 
Distance between the angles about "0024". (Fig. 7.) 
