Wallich, on Siliceous Organisms, 
47 
Greville^s ; the capitate extremity of basal ray being laterally 
emarginate^ central suture plane_, others angular. Diameter 
•0021. Fig. 10. 
From Salpse^ Indian Ocean. 
A. malleus, n. sp. — Rays linear^ in two or more pairs, 
arranged on each side of the malleiform extremity of the 
basal ray. Upper (i. e. inner) edge of basal ray free. 
Cellulation very conspicuous. Sutures plane. Diameter 
•0021. Fig. 11. 
From Salpa3, Indian Ocean. May, 1857. 
A. sarcophagus, n. sp. — Valve oblong, with a slight constric- 
tion near each extremity. Basal ray plane, and continuous 
with one of the true rays. Sutures plane. Cellules very 
large. 
The broadest portion of this species is always towards the 
extremity opposite the basal ray, thus giving the valve a 
somewhat pyriform or sarcophagus-like shape. Length 
•0018; breadth •OOOQ. Fig. 12. 
Indian Ocean. From Salpse. May, 1857. 
Section II. — More than one basal ray. 
A. Grevillii.—'BsiSsl rays three in number, united at the 
centre of valve by their capitate bases, and forming a 
Y-shaped figure. The remaining (eight) rays having cuneate 
bases, which are arranged between the angles formed by the 
decussation of the basal rays. Sutures of true rays plane. 
The free portions of both sets of rays are of the same size, 
and suddenly expand, giving a circular aspect to the central 
part of the disc. Diameter "0025. Fig. 15. 
Indian Ocean. May, 1857. 
I beg to associate this beautiful diatom with the name of 
one of our oldest and most acute microscopic observers. 
ASTEROLAMPRA, Ehr. 
Frustules free; disciform. Valves orbicular or sub- 
orbicular, with an indefinite number of hyaline rays, which 
are united together by their angular bases. Basal ray absent. 
Cellulation of inter-radial spaces hexagonal. Free margin 
of rays granulated. 
A. Marylandica, Ehr. — The only species noticed by 
Kutzing is the fossil one described under the above name by 
Ehrenberg, the number of rays being restricted to eight. 
Specimens in my possession exhibit six, seven, and twelve; 
rays, without the slightest structural diff'erence. Figs. 13 
and 14) are appended in order to show the wide range of form 
