GREVILLE, ON DIATOMACEA. 163 
AcuNnaNntTHES, Bory. 
A. angustata, n. sp., Grev.—Front view of valve very 
narrow ; length 0060"; breadth -O001”; striz 24 in :001”. 
(PIV ILI, fig. 9.) 
In Californian guano. 
I regret that I have had no opportunity of examining the 
side view of the frustule; but there can be, nevertheless, 
little doubt of the species being distinct from any of those 
previously described. The striz agree in number with those 
of A. subsessilis ; the relative length and breadth, however, 
of the valve, as seen in the front view, is so widely different 
from the proportions of the species above mentioned, that 
the possibility of its being a variety cannot be entertained. 
Bippurentia, Gray. 
B. longicruris, n. sp., Grev.—Valve on front view with a 
central inflation, bearing a solitary, very long spine; angular 
processes very long, awl-shaped ; structure minutely granu- 
late. (Fig. 10.) 
In Californian guano. 
After the warning contained in the admirable Monograph 
of Biddulphia so recently published by Mr. Roper, not to 
multiply species without having seen the frustule under its 
various aspects, how shall I venture to transgress so whole- 
some a rule in the present instance? All I can say is, that 
the frustule of which I now offer a figure is so far removed 
from any of the species now established, that I find it quite 
impossible to refer it to any of them. B. aurita is its nearest 
ally ; but if we adopt the character of that species as laid 
down by Professor Smith and Mr. Roper, we find the valve 
to possess a central elevation or inflation, on which are 
situated two or three or more spines. The angular processes, 
according to Smith, are “ horn-like, obtuse, inflated at the 
base.’ In the frustule now before me, the central elevation 
bears only a single spine, and that much longer and stronger 
than it ever occurs in B. aurita ; in fact, it is as long as the 
diameter of the entire frustule. Then the angular processes 
are also very long, somewhat acute, awl-shaped, without any 
inflation at their base. These distinctive marks, which, being 
as well seen in the front as in the side view, will, I trust, 
justify me in giving it at least a provisional place until ma- 
terials for a more perfect description shall be obtained. 
B. Roperiana, n. sp., Grev.—Valve elliptical-oval, with a 
central elevation, which, as seen in the front view, is depressed 
