90 
GjREviLLE, on New Diatoms. 
which it resembles closely in form. But it is separated at 
once by the distinct but delicate line which divides the angles 
from the centre, and which also gives a more angular cha- 
racter to the central area. The spines appear to be invari- 
ably placed upon these lines, and attract the eyes as points of 
light. 
Triceratium venulosum, n. sp., Grev. — Minute ; valve with 
straight sides and somewhat rounded angles ; surface marked 
with remotely scattered, minute puncta, and short vein -like 
lines given off in pairs from the margin. Distance between 
the angles -0020". (Fig. 21.) 
Hab, Barbadoes deposit, Cambridge estate; C. Johnson, 
Esq. 
A very distinct little species, without any appearance of 
;^seudo-nodules in the angles. 
Triceratium ohesum, n. sp., Grev. — Minute; valve with 
slightly concave sides and very rounded angles ; a few very 
short lines projecting from the margin, a few very minute 
puncta forming a central triangular figure, and a few others 
arranged in a line so as to cut off the angles. Distance be- 
tween the angles -0012^ (Fig. 11.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
The angles are perfectly smooth, and present no appear- 
ance of pseudo -nodules. The short lateral lines are equi- 
distant and five or six in number. 
Triceratium Rylandsianum, n. S})., Grev. — Small ; valve 
with straight sides and large, rounded, capitate angles cut off 
from the centre by a transverse line ; surface minutely gran- 
ulose j margin with a few remote puncta. Distance between 
the angles '0025^ (Fig. 6.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
A very remarkable and distinct species. The angles have 
the appearance of a circular loop without markings of any 
kind. The margin is strong, and extended round the angles, 
the transverse line cutting them off from the centre being 
equally strong. The marginal puncta (about 6 or 7) appear 
as if imbedded in the substance of the margin itself. 
Triceratium microstictum, n. sp., Grev. — Large ; valve with 
slightly convex sides and somewhat obtuse angles ; surface 
filled with minute radiating puncta; margin with a row of 
conspicuous granules, largest in the middle ; angles minutely 
punctate, cut off from the centre by a fine transverse line. 
Distance between the angles '0052''. (Fig. 17.) 
