32 
Greville^ on New Diatoms. 
spear-like apices; space between the horns excavated^ and 
filled up with a hyaline limbus. (Fig. 15.) 
Hab. Barbadoes deposit, Cambridge estate, along with 
the preceding; in slides communicated by C. Johnson, 
Esq. 
In this curious diatom we have a form very aberrant in its 
conical valve and diverging horns. Nevertheless the affinity 
may be distinctly traced. Here the hyaline limbus, filling 
up the cavity at the base, reappears as in former cases, termi- 
nating the horns, not in the shape of delicate spines, or 
minute triangular teeth, but in that of a most lethal-looking 
weapon — a strong angular acute spear, as long as the horn 
itself. The latter is robust and rough, with coarse points, 
forming, as it were, a very fitting, firm handle to the blade 
it supports. It would be not a little interesting to discover 
the frustules of so extraordinary a production in situ. It will 
probably prove the type of a new genus. Breadth of frustule 
•0035'', length to end of horns -0045''. 
H. ornithocephalus, n. sp., Grev. — Smooth, rectangular; 
valve with the angle produced into short, thick, straight, capi- 
tate horns, having a single triangular tooth ; space between the 
horns straight. (Fig. 16.) 
Hab. Barbadoes deposit, Cambridge estate, very rare ; in 
slides communicated by C. Johnson, Esq. 
This, it will be at once perceived, is an equally aberrant 
form ; and there can be little doubt that if we knew it more 
perfectly, it would, like the preceding, constitute a new genus. 
The horns do not form a straight continuation of the margin 
of the valve, but rise from a swollen base a little within it. 
They appear to be cylindrical, and terminate in spherical 
knobs, which, by the addition of the little lateral tooth, are 
irresistibly suggestive of a bird^s head. Breadth of frustule 
•0019", length '0016'', the horns occupying about two thirds 
of the space. I have only seen a single specimen. 
Triceratium. 
Triceratium Moronense, n. sp., Grev. — Large ; valve pul- 
vinate, with somewhat convex sides and prominent pseudo- 
nodules ; surface with rather widely separated and broken 
lines of minute, remote, radiating puncta, leaving a small, 
irregular, vacant space at the umbilicus. (Fig. 18.) 
Hab. Moron fossil deposit. Province of Seville ; C. 
Johnson, Esq. 
A beautiful and distinct species, very convex at the edge 
of the valve. The punctation constitutes the most distinc- 
