214 CONTRIBUTIONS 
ROTELLA. Lamarck. 
R. nana. Plate 6. Fig. 225. 
Description. Shell orbicular, flattened above, smooth, 
margin rounded ; substance of the shell rather thin ; spire 
nearly concealed ; outer lip sharp; callus impressed in the 
centre, bounded by a fine impressed line ; mouth nearly 
round. 
Length 1-20th, Breadth nearly .1, of an inch. 
St Mary’s, Maryland. John Finch. 
The smallest figure is of the size of nature. 
Observations. This very minute Rotella is very much 
flattened above, and the last whorl nearly covers over the 
spire. The number of whorls is doubtful; perhaps they 
do not exceed three. The margin is rounder than usual 
in this genus. A single specimen only has been observed 
by me, and this was discovered in the sand, taken from the 
cavity of a larger shell. 
I am not aware that the genus Rotella has before been 
observed in a fossil state, in this country or in Europe. 
M. Deshayes gives in his Tertiary Tables four recent spe- 
cies, but none fossil. 
