210 WEST AMERICAN SHELLS STEARNS. 



(2) R. Bemondi Gabb, near Arivechi, valley of Sabuaripa, in the prov- 

 ince of Sonora; also a variety {/i, C. and F.) of same. 



(3) R. teres Menke, province of Puebla ; special habitat not stated ; 

 of this there is also a rariety {/3, C. and F.). • 



(4) R. goniostoma Pfr., Mexico; special habitat not given. 



(5) R. Pilocerei Pfr. The typical form was found in the neighbor- 

 hood of Cuautla de las Amilpas, province of Puebla, and a variety (/i, 

 0. and F.) ; no other locality given than " Mexico." 



(6) R. Tryoni Pfr., Matamoras de Izucar, State of Puebla, and a va- 

 riety of same (/?, C. and F.). 



(7) R. Gealei H. Adams, Putla, in the State of Oajaca. 



(8) R. Coahuilensis W. G. Binney, Oienga Grande, State of Coahuila 



(9) R. cretacea Pfr., " Mexico." 



(10) R. imbricata Martens, habitat as given " ? Mexico," is in all prob- 

 ability correct; "I'ensemble de ses characteres" are, according to Crosse 

 and Fischer, sufficient to indicate its geographical relations. 



(11) R. microstoma Pfr., ? Mexico. The remarks as to habitat in con- 

 nection with the previous species may be applied to this with equal 

 propriety. 



(12) R. Goldfussi Menke, "Texas, on the Blanco," W. G. Binney. 



(13) R. Roemeri Pfr., "New Braunfels and Howard Springs, Texas, 

 W. G. Binney. 



Of the varieties given by Crosse and Fischer, distinguished as "/?" of 

 the species Pfeiferi, Bemondi, teres, Filocerei, and Iryoni, the number of 

 the whorls, size, and sculptural development are, in the main, the basis 

 of varietal distinction. To these may be added another characteristic 

 more or less mutable, the extent of the projection of the basal whorl at 

 its termination from the body of the shell. This varies considerably as 

 a comparison of many individuals will show. The other characters are, 

 we may assume, equally unstable or nearly so, and a large or extensive 

 geographical series would without doubt connect the admitted species 

 and so-called varieties by so gradual a blending of one into the other 

 as to eftace the present lines of demarkation. The authors above quoted 

 suggest that R. Tryoni may prove to be a variety of R. Pilocerei ; the 

 latter is largely represented in the national collection, as well as Tryoni; 

 a comparison of these hardly sustains the suggestion. Dr. Palmer 

 found somewhere in his rambles in Arizona, Mexico, or New Mexico, a 

 somewhat dwarfed and rather solid form of Rolospira, that with the ex- 

 ception of size and solidity may be regarded as R. Pilocerei (Mus. No. 

 29303), and it is so named in the collection. 



A comparison of individuals shows that the shape of the mouth, the 

 strength of the sculpture, the projection of the basal whorl at its termi- 

 nation, and size, are all variable factors more or less coincident with 

 proximity or remoteness of habitat, or in other words with geographical 

 relations. 



