= Sketch of the Infusoria of the family Bacillaria. 95 
IT select from the species of Coscinodiscus, described by Eh- _ 
renberg, the following, as apparently identical with American — 
species from Richmond, Va. In connection with the description, 
f I give a reference to figures drawn by me from fossil American 
species, long before Ehrenberg’s characters for the Species were 
received. 
Manicienbictati lineatus. (PI. 2, fig. 12, a, b) omeea marked* 
by small cells disposed in a series of parallel and transverse lines. 
Found fossil in the chalk marl of Caltasinetta, and. in the live 
: condition at the Cuxhaven. The cells in this species form par- 
allel lines in whatever direction they may be viewed. In large 
and well preserved fossil specimens, as many as twenty five 
openings were seen near the circumference. Within the live 
forms, numerous yellow vesicles are sometimes seen, as in Gail- 
lonella. Diameter of fossil, ay to =i,th; living ;;;,th 
to siath. Fossil at Richmond, V. 
| | radiatus. (Pl. 2, fig..14.) Carapace large, 
| marked with cells of moderate size, disposed in lines radiating 
from the centre. ‘Towards the margin the cells become smaller 
in size. Very abundant in fossil state at Oran, alive near Wis- 
mar and Cuxhaven, ;3,th to ;1;th. — Fossil at Richmond, Va. 
Coscinodiscus Argus, (? var. of C. radiatus.) Carapace with 
large. cells at the centre, and smaller ones at the Lae anion 
ee Se ee 
te 
oar es ~ satis 
Li the order of the rays being often interrupted. 
k . Fossil. at Oran and Caltasinetta in chalk marl, rina ine sea 
is water at Cuxhaven. The cells of the discs from Oran vary very 
much in size. The ova are of a greenish color in the living 
forms, which are very rare. Diam. ;1,;th to i;th. Fossil at 
Richmond, Va. 
_ Coscinodiscus oculus-iridis. Carapace marked with rather 
large radiant cells, except near the centre and circumference, 
where they are smaller. Some of the larger cells in the centre 
form a sort of star. Fossil in the chalk marl of Greece; alive 
hear Cuxhaven. Diameter, ;};. This large species is curiously 
marked, whilst under the microscope, with colored rings, which 
are apparently caused by the peculiar arrangement of the cells. 
There are generally from five to nine large cells at the centre. 
Specimens are found in the infusorial stratum of Richmond, Va., 
Which have the star-like centre and probably belong to this 
ae ee ee ee ne ep eee = ee 2 eee ane 
* 
sci ll 
