impressions are indistinctly seen, but appear to be formed on 
the same plan as those of the ventral valve of the genus. 
The above description is drawn up on one exterior, and sey- 
eral interiors of the same valve, apparently the ventral valve. 
The exterior is very like that of O. desguamata, and is of the 
same size, but the interior shows it to be an entirely distinct 
species. 
Length of the largest specimen seen, seven lines; width about 
the same, or slightly less. 
Occurs at Trois Pistoles. Collected by T. C. Weston. 
Platyceras primevum.—Shell minute, consisting of about two 
whorls, which as seen from above are ventricose, but most nar- 
rowly rounded at the suture; the inner whorl scarcely elevated 
above the outer. The under side is not seen in the specimen. 
Diameter, measured from the outer lip across to the opposite 
side, one line; width of last whorl at the aperture, about one 
third of a line. 
Collected at Bie by T. C. Weston. 
Proposed new genus of Brachiopoda. 
rella are, thus, as follows :— 
Trimerella.—Cavities in both valves. the 
Monomerella.—Cavities in the ventral valve, but none 12 
This genus was discovered in the spring of 1871, at Hespe™® 
‘Ontario, in the Guelph limestone, by T. C. Weston. pee 
venturing to describe it, I sent a specimen to Mr. Davidson | us, 
on returning it he stated that he considered it to be a new er 
“very closely allied to Trimerella” Lately I received @ 
from him in which he states that he has obtained the same ge" 
