182 CONTRIBUTIONS 



GENUS OLIVA. Lamarck. 



0. constricta. Plate 6. Fig. 195. 



Description. Shell cylindrico-f usiform ; substance of the 

 shell rather thick ; spire elevated, pointed ; whorls six, flat 

 above ; columella with about five irregular folds near the 

 base ; mouth narrow, about three fifths the length of the 

 shell. 

 Length .9, Breadth .3, of an inch. 



Observations. There is a great resemblance between 

 this species and the clavula (Lamarck), and it may be 

 doubtful if they should be separated. Our shell has a 

 shorter mouth, a higher spire, and is, perhaps, more 

 slender. 



O. gracilis. Plate 6. Fig. 196. 



Description. Shell subfusiform, polished ; substance of 



the shell thin ; spire elevated, pointed ; whorls five, slightly 



convex ; columella with five or six irregular folds near the 



base ; mouth narrow, about one half the length of the shell. 



Length 7-20ths, Breadth .l,of an inch. 



Observations. The graceful form of this little species, as 

 well as its size, will easily distinguish it from the following 

 one. It is less cylindrical than that which precedes it, 

 and properly placed between both, as it bears some of the 

 characters of both. 



