TO GEOLOGY. 101 



third the length of the shell ; columella smooth, somewhat 

 thickened at base ; outer lip edged. 



Length 7-20ths, Breadth 3-20ths, of an inch. 



Observations. In this species, which is the largest of 

 those I have noticed, the inner lip is less thickened than 

 those which follow. 



P. notata. Plate 4. Fig. 80. 



Description. Shell subulate, highly polished ; substance 

 of the shell rather thick ; apex acute ; suture very small ; 

 whorls eleven, very flat, each one being marked with an 

 impressed oblique line of growth ; mouth small, acutely 

 angular above, about one fifth the length of the shell; colu 

 mella somewhat thickened at the base ; outer lip somewhat 

 arched, with an obtuse edge. 



Length 7-20ths, Breadth .1, of an inch. 



Observations. This pretty little species is more attenu 

 ate than the preceding, and is remarkable for the slightly 

 oblique lines of growth in each whorl, and which recede 

 spirally from the mouth to the apex. 



P. lugubris. Plate 4. Fig. 81. 



Description. Shell rather subulate, polished ; substance 

 of the shell rather thin ; apex rounded ; suture linear ; 

 whorls seven, flattened; mouth subovate, about one fifth the 

 length of the shell ; columella slightly recurved at base ; 

 margin thickened all round. 



Length 3-20ths, Breadth l-30th, of an inch. 



