242 



gently concave. The second, inside of the first, is gently convex, and 

 inclined at an angle of from 70° to SO^'. Surface unknown. 



Width of an average specimen 20 lines ; width of last whorl 6 lines ; 

 height of last whorl about 6 lines. 



When the upper side alone of this species is seen, it cannot be distin- 

 guished from 31. affinis ; the size of the shell and proportions being about 

 the same. The umbilicus, however, is altogether different. Some of the 

 specimens have thicker whorls, and approach M. Emmonsi in form. 



Locality and Formation. — K, L, Table Head and Point Rich, New- 

 foundland ; Quebec group. 



Collector. — J. Richardson. 



Maclurba Emmonsi. (N. sp.) 



Fig. 227. 



Fig. 227. — Maclurea Emmonsi. a, front view of a small specimen ; b, spire of a 

 large specimen; c, spire of a. 



Description. — Shell from one to three inches across, usually about two 

 inches ; spire flat, of three or four whorls, somewhat rapidly increasing in 

 size ; outer edge obtusely rounded ; umbilicus from one-half to three-fourths 

 the whole width with an acute edge. On the upper side the smaller 

 whorls are, in some specimens, quite flat, and in others convex ; the outer 

 margin of the last whorl, in all the specimens seen, is obtusely rounded. 

 The edge of the umbilicus, in the perfect shell, is thin and quite sharp, 

 with a concave band just below it ; in the casts it is acutely rounded. 

 With the exception of the concave band, the inner side of the whorls in the 

 umbilicus is gently convex. The whorls are all seen in the umbilicus, but 

 the edge projects only slightly. The height of the shell is nearly two- 

 thirds its width. Surface unknown, but probably finely striated. 



