454 Fossils of the Chazij Limestone. 



Locality and Formation. — Near L'Orignal. Chazy Limestone. 

 Collector. — R. Bell. 



Pleurotomaria immatura, N. s. 



Description. — Spire nearly flat, the apex elevated four or 

 five lines above the margin in specimens one inch and a half 

 wide, the last whorl depressed one and a half lines below the 

 preceding; base depressed sub-hemispheric or conical; whorls, 

 four or five, with a narrowly-rounded outer edge; width, from 

 one inch to one inch aid a half; height, a little more than half 

 the width. 



The band in this species is apparently smooth, and placed pre- 

 cisely on the outer margin of the whorl, where it forms a rounded 

 edge nearly a line in thickness, just above and below which the 

 whorl is suddenly a little concave. The apex is not acute but 

 rounded, and the suture for the first two or three whorls is not 

 distinct, but afterwards becomes more apparent as the succeeding 

 whons become depressed. Owing to the depression of the outer 

 w r horl the spire is semi-turretted, the outer margin of the penul- 

 timate whorl forming a step-like elevation above the inner margin 

 of the last. The surface is marked by rather fine backward cur- 

 ving striae, and narrow irregular undulations of growth. The 

 upper surface of the first and second whorls forming the rounded 

 apex of the spire are gently convex, but the outer ones are flat, 

 or a little concave. 



I have seen no specimens of this species with the base well 

 exposed, but the rounded edges of the whorls and semi-turretted 

 spire are characters sufficient to distinguish it from any other 

 Chazy species. From what I have seen, I think the umbilicus 

 must be either very small or entirely closed. 



The proportional width of the whorls is variable. In one spe- 

 cimen thirteen lines wide the outer whorl has a breadth on its 

 upper flat surface of three lines, which is also its width in another 

 individual with a spire sixteen lines wide. 



Locality and Formation. — Tw-o miles north of Montreal. Chazy 

 Limestone. 



Collector — E. Billings. 



Pleurotomaria calyx, N. s. 



Description. — Spire nearly flat, with an acute or sharply- 

 rounded outer margin ; base conical, more or less produced below ; 



