120 
GnEviLLE^ on Asterolampra. 
areolated segments nearly square at the base ; angular bend 
of tbe umbilical lines situated towards the outer extremity ; 
median lines scarcely passing beyond the central pointy 
arched at the top^ then contracted^ afterwards more or less 
divergent. Diameter '0028'' to '0036". (Fig. 18.) 
Asterornplialus Brookei, Bail., Sill. Journ., 2d ser., vol. xxii, p. 2, PI. 1, 
fig. 1. 
Hab. — Sea of Kamtschatka^ in soundings made by Lieut. 
Brooke^ in 1700 fathoms^ Professor Bailey. Atlantic 
soundings, Mr. Boper. 
Were it not that I possess specimens of this species from 
Professor Bailey himself,, I could scarcely have recognised it 
from the brief notice he has given of it in ' Silliman^s Jour- 
nal/ and still less from the figure which accompanies it. The 
fact is, the characters which he attributes to it are now 
shared in common with other species, and we have to look 
for other distinctive marks. In some points, the species is 
allied to A. Roperiana, being apparently quite circular, and 
having the base of the segments square, or nearly so. An 
additional resemblance is also found in the median lines, 
which scarcely cover the central point, being arched at the 
top, then contracted, and lastly expanded, though not to the 
same extent as in the species just mentioned. Professor 
Bailey^s figure represents the base of the segments as 
decidedly curved as in A. Marylandica, but they are more 
nearly square, and in some valves quite so. The umbilical 
lines radiate from the upper half of the median lines, and 
are sometimes branched. There is an angular bend, nearer 
to the outer extremity than in any other species, and at each 
angle the minute spine-like process indicates probably the 
base of a ramulus. This may also be seen at the base of the 
median lines. The areolation is conspicuous. The number 
of rays, according to Bailey, varies from seven to thirteen, or 
more ; in my specimens they are from ten to twelve. The 
frustule, when perfect, is very convex. 
16. Asterolampra Roperiana, n. sp., Grev. — Valve cir- 
cular ; hyaline area centrical ; areolated segments square at 
the base, almost equal ; rays seven ; median lines passing 
round the central point in a semicircle, then contracted 
below, and lastly widely expanded. Diameter '0028" to 
•0066''. (Fig. 14.) 
Hab. — Indian Ocean, in soundings made by Captain 
Pullen, in 2200 fathoms. 
It is unnecessary to repeat the remarks which I have 
already made on this most interesting diatom, as constituting 
