TO GEOLOGY. 181 



very much thickened, swollen and projecting about the 

 middle ; outer lip sharp. 

 Length 2.5, Breadth 1.5, of an inch. 



Observations. This is the largest Jlnolax, recent or fossil, 

 I have seen. It resembles, in its general character, the 

 altile and subglobosa (Conrad), and particularly so in the 

 great mass of deposit on the inner lip. It differs from them 

 in size, and in being more ovate. I have had it in my 

 power to examine but a single specimen of this species. 

 Other individuals may present different characters. 



A.plicata. Plate 6. Fig. 194. 



Description. Shell subfusiform, turrited, longitudinally 

 folded above ; substance of the shell rather thick ; suture 

 impressed in the callus, spire elevated, not pointed at the 

 apex ; whorls six, flattened above ; mouth ovate, half the 

 length of the shell ; outer lip sharp. 



Length .4, Breadth .2, of an inch. 



Observations. This species most resembles the scamba 

 (Conrad), but is a much smaller shell, and may at once be 

 distinguished by its longitudinal folds. 



Four species of this genus have been observed in the 

 London Clay of England. In the Tertiary Tables of M. 

 Deshayes we find nine. Of these five are found in the Paris 

 basin. Mr Conrad has observed four from the same stratum 

 at Claiborne, whence those above described were taken. 



