Greville^ on New Diatoms. 
5 
Xanthiopyscidce. The valves are remarkable for the sinuous^ 
inosculating veins and furrow-like interstices. The veins are 
produced here and there, into elevated points, or short spines, 
not always very obvious, unless in an oblique or front view. 
The genus is related on the one hand to Pyxidicula and its 
allies, on the other, to the Coscinodiscece. 
Liradiscus Barbadensis, n. sp., Grev. — Valve circular, with 
a wide sinuous reticulation passing towards the margin into 
radiating lines. (Fig. 14.) 
Hab. Barbadoes deposit, Cambridge estate; in slides 
communicated by C. Johnson, Esq. ; rare. 
Valve hyaline, the large flexuose reticulation occupying 
from one half to nearly the whole of the disc, and much less 
hispid than in the following species. I have never seen the 
front view. Diameter about '0030'^ 
Liradiscus ovalis, n. sp., Grev. — Valve elliptic-oval, the 
sinuous reticulation reaching nearly to the margin, more or 
less hispid. (Figs. 15, 16.) 
Hab. Barbadoes deposit, Cambridge estate, frequent ; in 
slides communicated by C. Johnson, Esq. 
The valve varies considerably in the size of the reticulation, 
and in the degree of hispidity. In some specimens it is diffi- 
cult to perceive the spines in a side view, except where they 
rise up close to the margin. Long diameter about -0025'^ 
I am under an impression that a third species exists in tlie 
deposit, with a smaller reticulation, and the little spines 
crowded. 
AULISCUS. 
Auliscus notatus, II. Grev. — Small; valve strictly cir- 
cular, with two processes ; whole surface covered with nearly 
equally distributed minute puncta. (Fig. 2.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides 
communicated by C. Johnson, Esq. ; very rare. 
This elegant minute diatom while evidently allied to A. 
punctatus, is, I believe, truly distinct. The valve is very 
much smaller and strictly circular; and the punctation is 
uniform, not exhibiting the slightest tendency to radiation. 
In the specimens which I have seen, the processes are situated 
at some distance from the margin. Diameter '001 8'^ 
Atdiscus Barbadensis, n. sp., Grev. — Valve elliptic- oval, 
with a small umbilicus, 2 processes, 4 radiating lines arranged 
in a cruciform manner, and 2 less conspicuous lateral ones. 
(Fig. 1.) 
