GiiEviLLE_, on New Diatoms. 
7 
gida, which it resembles in general form and dense structure, 
and especially in the short, broad, fiat processes. I have been 
unable to perceive any trace of spines, nor is there any 
indication of a rough line or fringe of apiculi, like that in the 
valve of B. turgida. Like most of the other members of the 
genus, our new species varies greatly in size. 
Biddulphia? mammosa, n. sp., Grev. — Valve in front view 
produced at the angles into large, elliptical, mammseform, 
minutely punctate processes ; median surface slightly convex, 
and transversely remotely striate; the rest of the surface 
smooth. Length of valve '0040". (Fig. 16.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
We have here another of the dubious forms of which so 
many occur in the Barbadoes deposit, and of which it is 
desirable to place on record. It is fortunate that although, 
in the absence of the end view of the valve, we cannot 
describe the exact contour, characters amply sufficient for 
the determination of species are obtained from the front 
view. At least this has been found to be the case in the 
fossil Biddulphice and Hemiaulidce from Barbadoes. The end 
view of the valve of the present species must be very beautiful, 
being apparently composed of a series of long, linear, trans- 
verse cellules, traversed by a median line. 
Triceratium. 
Triceratium Robertsianum, n. sp., Grev. — Large ; valve 
with gibbous sides and subobtuse, slightly produced angles, 
a short, horn-like process at each angle, and 1 — 2 strong 
spines, arising from the surface within the margin on each of 
the sides ; cellulation hexagonal, large, equal ; margin broad, 
elevated. Distance between the angles -0042'". (Fig. 22.) 
Triceratium grande f — ' Brighton Mic. J our.,^ vol. i, p. 
249, pi. iv, fig. 8. 
Hab. Woodlark Island, South Pacific ; in a dredging com- 
municated by Dr. Roberts, of Sydney. 
For nearly two years I have refrained from making any 
use of the drawing of this diatom, in the hope that I might 
be enabled to come to some satisfactory understanding rela- 
tive to T. Favus and its varieties. In the mean time multi- 
tudes of that species have come under my observation, and I 
have met with no form which tended to unite the one under 
consideration with that species. T. Favus frequently occurs 
with the sides of the valve " slightly convex," in accordance 
