CRETACEOUS FOSSILS. 119 



Surface marked by fine imbricating lines of growth, which arise 

 at the suture, pass obliquely backwards around the whorl to the 

 umbilicus, presenting a finely crenulated appearance on the upper 

 angle of the whorl. Umbilical margin very coarsely crenulated. 

 Aperture rounded, subquadrate. Body whorl flat, or sharply 

 rounded and channelled above, nearly flat on the side, sloping 

 outwards and convex below. 



Height, .15 inch ; width, .19 inch. 



Locality : Three specimens were collected by Dr. Cooper, near San Diego. 



M. GLOBOSA, n. s. 



PL 29, Fig. 225. 



SHELL very small, subglobose ; spire moderately high ; whorls 

 five to five and a half, rounded, except the body whorl, which is 

 sometimes obliquely flattened on the sides. Mouth subcircular, 

 acute behind ; lips simple. Umbilicus perspective, creuulated on 

 the margin. Surface polished, marked by very fine lines of 

 growth. 



Figure, highly magnified. 



Locality: Near Benicia (in Division A.). Collection of Mr. llemond. 



This shell is easily distinguished from M. crenulata by its larger size, more 

 globose form, and its higher spire. Unlike that species, it is not truncated on the 

 upper margin of the whorls, and it only occurs in the lower member of the forma 

 tion ; while M. crenulata is, so far as our information goes, peculiar to the upper 

 member. 



DISCOHELIX, Dunker. 



(Orbis, Lea, not Schrb't, nor Lacep.) 

 D. LEANA, n. s. 



PL 20, Fig. 75. 



SHELL discoidal, flat ; spire none ; whorls five, in contact, but 

 not enveloping; section circular; the first whorl slightly more 



