GrevillEj on New Diatoms, 
89 
Hab. Barbadoes deposit^ Cambridge estate; C. Jolinson^ 
Esq. 
At first sight this species might be taken for a small variety 
of Auliscus RalfsianuSj which it greatly resembles in the pro- 
cesses and in the character of the reticulation. The latter^ 
however^ is much smaller and destitute of puncta. The ex- 
treme margin is minutely headed, the beads 17 in -OOl"', a 
character never observed^ I believe^ in the Aulisci. The 
present species is closely allied to E. oculatus, found in the 
Monterey fossil earth, from which it differs in its much 
smaller diameter, and in the cellules not diminishing in size, 
and never becoming in the slightest degree radiate toward 
the margin. In proportion to the size of the disc, the pro- 
cesses are broader, even, than in E* oculatus. 
Triceratium. 
Triceratium prcetenue, n. sp., Grev. — Minute ; valve with 
concave sides, the concavity interrupted by a small convexity 
in the middle ; the attenuated angles with a minutely rounded 
apex containing an indistinct pseudo-nodule ; surface with 3 
central spines, and radiating puncta, the margin with a row 
of larger cellules. Distance between the angles from '0013'' 
to -0020". (Fig. 16.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides 
communicated by C. Johnson, Esq. 
In all the examples which I have seen, the central spines 
are present, although sometimes very inconspicuous. The 
central portion of the valve is circular and somewhat concave, 
and the minute puncta radiate to the boundary of this area, 
while beyond it they appear to be disposed without any par- 
ticular order. The margin of that part which may be said to 
belong to the angles, is furnished with a row of larger puncta 
or cellules. 
Triceratium perminutum J n. sp., Grev. — Minute; valve with 
concave sides (slightly convex in the middle portion) ; angles 
attenuated, obtuse, with a minute indistinct pseudo-nodule, 
separated from the centre by a slender line on which is 
situated a minute spine; puncta radiating, about 4 larger 
marginal ones in the angles. Distance between the angles 
W15". (Fig. 18.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
In some respects this little species is allied to the preceding. 
