238 



is preserved, but, as seen in the cast of the interior, deeply impressed. 

 The outer side of the body-whorl is gently convex, and sloping to the 

 edge of the umbilicus at an angle of from 60 to 70 with the plane of 

 the flat side of the shell. The height of the aperture appears to be a 

 little less than half the whole width of the shell. The edge of the 

 umbilicus is acutely rounded, not acute as in M. Ummonsi and M. affinis. 

 The inner side of the whorls in the umbilicus is gently convex, and some- 

 what sloping ; the edge exposed in staircase form to the apex. Surface 

 unknown, but most probably finely striated. 



In a specimen 13 lines across, consisting of three complete whorls, the 

 outer whorl is 4 lines wide ; height of the aperture 6 lines ; width of the 

 umbilicus 5J lines. 



In a specimen 33 lines wide, consisting of four whorls, the outer whorl 

 is 9 lines wide ; aperture and umbilicus not exposed. 



The proportions of this species are very nearly those of M. crenulata, 

 and, in the condition of casts, the two cannot be distinguished from each 

 other. When the shell is preserved, the differences become at once 

 apparent. 



In M. crenulata the umbilicus is narrower ; the edge bears a crenu- 

 lated band ; the inner side of the whorl, in the umbilicus flat ; and the 

 height of the aperture is a little more than half the whole width of the 

 shell. 



The operculum found with it has no muscular process, as in M.-Logani. 



This species occurs also in a somewhat lower geological position than 

 M. crenulata. 



Locality and Formation. F, G, H, Port aux Choix, Table Head, 

 Cape Norman, and Pistolet Bay, Newfoundland ; Quebec group. 



Collector. J. Richardson. 



MACLUREA AFFINIS. (N. sp.) 



Fig. 224. 

 Fig. 224. Maclurea affinis. a, the spire ; 6, section. 



