130 THE NAUTILUS. 



The shape, indeed, is almost exactly that of the west Cuban M. 

 denticulatus a species less closely striated and having a rimate base 

 and built-tbrward columelhir margin. M. petitiunus has narrower, 

 more separated striaj and no denticulation below the suture ; more- 

 over, it has a shortly rimate base and fbrwardly-built columellar 



margin. 



M. perconicus (which I described as a variety of petitianus") is 

 doubtless a species distinct from pttitiantu, differing in sculpture 

 and the columella, which is not in the least built forward. It is 

 more strictly conic than trinidadensis , without sutural denticles, 

 otherwise the same. M. palenguensis, which I have not seen, seems 

 to be broader with a larger aperture. 



The specimens recorded as M. turricula Pfr. from Trinidad were 

 probably trinidadensis. I have not seen the form reported from 

 Cabo Cruz. 



MACROCERAMUS OANIMARENSIS (Pfr.). 



A single specimen, typical in form and sculpture but white with 

 a corneous base, I found among rocks in a precipitous, shaded place 

 on the northwest side of La Vigia. It has already been reported 

 from Trinidad. 



MACROCERAMUS CANIMARENSIS ROTUNDIBASIS, n. subsp. 



The shell differs from canimarensis by having only a very weak 

 trace of the subperipheral keel (which is strongly developed in cani- 

 marensis); the base being much more convex than in canimarensis, 

 and not so strongly striated. 



" San Jose rocks " near Sancti Spiritus. 



I did not find this species living, but dug it from a bed of clay 

 formed by disintegration of the limestone. 



A LIST OF MOLLUSCA FROM THE MUSSELSHELL VALLET, MONTANA. 



BY S. STILLMAN BERRY. 



Except for the brief lists by Squyer (NAUTILUS, Vol. VIII, pp. 

 63-65, 1894) and Elrod (Bull. Univ. Montana, No. 10, pp. 170-174, 

 1902), there are very few molluscan records extant for the entire 



