The Nautilus. 



Vol. XXIX. JANUARY, 1916. No. 9 



HELICES OF LOWER CALIFORNIA AND SINALOA. 



BY H. A. PILSBRY. 



In my "Notes upon some Lower Californian Helices," Proc. 

 Acad. Nat. Sci. Phila. 1913, descriptions and figures were 

 given of the Helices of the west coast and coastal islands of the 

 peninsula. The inland group remains to be considered here.' 



While it seems likely that some or all of the Lower Californian 

 mountain Helices will prove to belong to the section Eremarionta 

 of the genus Micrarionta, yet none are known anatomically, and 

 we have as yet no way to tell them by the shells alone from 

 Sonorella. It seems best therefore to refer all Sonorella-\\ke 

 shells of the Southwest to that genus until they are proved to be- 

 long elsewhere by dissection of the animal. 



Group of Sonorella lohrii. 



Helices of this group are much depressed, with a broadly 

 open umbilicus, more or less overhung by the dilated columellar 

 lip. They have the color and texture of Sonorella. 



' In the paper just mentioned, I ranked Ifvlix caneactns Adams and Reeve as 

 a subspecies of Micrarionta veatchii (p. 386). This was of course an oversight, 

 since //. canescens was described first. It will probably be best to leave both 

 stand as species until their intergradation is demonstrated ; but if they do 

 intergrade, then veatchii will take the trinomial. 



