\ 
TO GEOLOGY. 65 
been observed, eight being from the Crag. Lamarck does 
not mention any fossil species. M. Deshayes gives nineteen 
species in his Tertiary Tables. Mr Say has noticed two 
species in the Tertiary of Maryland; Mr Conrad two in 
that of Claiborne. 
FAMILY CONCH. 
GENUS CYTHEREA. Lamarck. 
C. globosa. Plate 2. Fig. 40. 
Description. Shell very much inflated, subrotund, very 
finely and transversely striate; swollen over the umbones; 
lunule widely and beautifully cordate; beaks very large, 
recurved; teeth elevated and disposed to be conical ; exca- 
vation of the palleal impression conical; cavity of the shell 
very deep and rounded; margin entire. 
Diam. 1.1, Length 1.3, Breadth 1.6, of an inch. 
Observations. This is perhaps the most globose of all 
the species yet known. It is remarkable for its capacity 
and its high recurved beaks, in which it has some resem- 
blance to the genus Isocardia. It is this which gives the 
impression of the ligament a curve of smail radius. The 
excavation of the palleal impression is more angular than 
in any species I have noticed. The two central teeth in 
the right valve are erect and close, with a deep cleft be- 
tween them. On the edge of the right valve there is a 
I 
