No. 186.] 



IT 



The accompanying figures are illustrations of one of the typical species of 

 Mr. Conrad. 



Platyceras ventrioosum. 



The following figures are of other species, where the last volution is free, 

 there being one or two closely contiguous turus. at the apex : one of them 

 is deeply sinuate at the margin. 



Plattceras trilobatum. 



Platyceras intermedium. 



expansion of the columellar lip, and its partial or entire union with the volution. 

 presenting all the appearance of a thin columella with a deep umbilicus. An 

 approximation to this condition is likewise shown, more or less complete, iu some 

 of the figures on Plates 117 and 118, Yol. iii, Pal. New-York. 



[Assembly No. 186.] 3 



