44. 
Greville, on New Diatoms. 
Strangulonema Barbadense, n. sp., Grev. — (Fig. 2.) 
Hab. Barbadoes deposit^ Cambridge estate ; in slides com- 
municated by C. Johnson, Esq.; extremely rare. 
We have here another filamentous diatom, which, like the 
preceding, cannot be referred to any existing genus. Only 
two specimens have been observed, neither of them possessing 
more of the filament than is given in the figure, which, how- 
ever, may fairly be assumed to represent a perfect portion. 
Commencing with the frustule, where division takes place, it 
may be compared to two decanters soldered together at their 
mouths. The parts representing the bodies are ornamented 
with punctiform cellules, arranged in close parallel lines as 
far as the shoulders, where a sudden contraction in the dia- 
meter occurs, forming the neck of each decanter, and which 
is quite smooth, while the resemblance to the rim of the 
mouths is carried out by the sudden expansion of the neck 
into a rather broad disc, equal in its lateral diameter to that 
of the frustule at the opposite ends. This ring-like disc is 
marked on its circumference by a deeply indented, rather 
faint line, somewhat like that which is produced by the meet- 
ing of the teeth in cog-wheels, and which, of course, suggests 
the idea of separation ; but I have been unable to ascertain 
whether this be really the case. On the other hand, the 
suture at the broad ends of the frustule is conspicuous. 
Length of frustule -0040^'; diameter -OOICK^ 
COSCINODISCUS. 
Coscinodiscus splendidus, n. sp., Grev. — Disc large, convex ; 
cellules large, hexagonal, all equal except those of the outer 
row, which are generally more or less oblong ; margin quite 
smooth. (Fig. 3.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. J ohnson, Esq. 
A most beautiful species, and not very rare in some 
portions of the sample of the deposit which has furnished 
so many good things ; for it is a curious circumstance, and 
not uninstructive to those who may be engaged in examining 
this deposit, that even in the same small lump one part will 
often be found richer than another. Of all the slides 
mounted by my indefatigable friend (and their name is 
legion) from one and the same general sample, a proportion 
only contain the species now described ; and, in like manner, 
a number of other fine forms appear to be most unequally 
distributed. It was my friend^s custom to chip off and clean 
a piece of the indurated earth from time to time, and, un- 
