88 Greville^ on New Diatoms, 
cone, instead of being continued in a horizontal direction, as 
in extans, 
AULISCUS. 
Auliscus ornatus, n. sp., Grev. — Small ; valve circular, with- 
out any umbilical space, the whole surface very minutely 
granulose; processes 5. Diameter '0027^^ (Fig. 2.) 
Hab, Barbadoes deposit, Cambridge estate; in slides 
kindly communicated by C. Johnson, Esq, 
The more recently discovered species of this beautiful 
genus considerably disturb what have been usually regarded 
as its typical characters. In A. Ralfsianus, it is with difficulty 
that any trace of converging lines can be perceived through 
the meshes of the network which appears to envelope it. In 
A. ambiguus the entire surface is filled up with a very minute 
cellulation, not the slightest convergent arrangement of any 
kind being apparent. And now we have a species in which 
the surface is throughout, uniformly and exceedingly minutely 
granulose. In addition to this peculiarity it stands alone in 
possessing five processes ; and as the alternating ones of the 
lower valve are almost equally conspicuous, the circle is 
nearly filled up. The occurrence of this diatom tends to 
confirm the idea previously thrown out, that the number of 
processes may furnish a reliable character. 
EUPODISCUS. 
Eupodiscus trioculatuSj n. sp., Grev. — Valve, with 3 large, 
flat, circular processes ; surface minutely reticulato-ceilulate. 
Diameter -0035^ (Fig. 3.) 
Hab. Barbadoes deposit, Cambridge estate; C. Johnson, 
Esq. ; R. K. G. 
It is quite possible that this diatom, three specimens of 
which are now before me, may belong to the genus Auliscus, 
as the three processes appear to point in that direction. But 
in the absence of characters more strongly distinctive of that 
genus, I consider it a safer proceeding to place it in Eupo- 
discus. Indeed it seems to evince considerable affinity with 
the following species, as well as with E. oculatus. 
Eupodiscus Barbadensis, n. sp., Grev. — Disc irregularly 
reticulato-ceilulate, the cellules being equal in size through* 
out ; processes 2, large, flat, circular ; margin with a row of 
very minute granules. Diameter -0030''. (Fig. 4.) 
