Indio (Davidson) fide Stearns; (R. E. ('. Stearns) fide Stearns ; 

 (H. Hemphill) fide Pilsbry, (H.Hannibal); (semifossil) Walters 

 (R. E. ( '. Stearns) fide Stearns. (B. X. Jackson); (semifossil) 

 Dos Palmos (R. E. C. Stearns | fide Stearns; (semifossil) Vol- 

 eano Springs (R. E. C. Stearns) fide Stearns; (semifossil) road 

 from Carrizo Creek- to Laguna .Mountain below old beach-line 



(Mrs. < '. Stephens). 



Ash Canon, Euachuca Mountains (L. E. Daniels) fide 

 Pilsbry and Perriss; spring, Tanner Canon (Pilsbry and 

 Ferriss) fide Pilsbry and Ferriss; 



Arizona Desert ( R. E. C, Stearns) fide Pilsbry. 



VALVATIDAE. 



Valvata tricarinata (Say). 



Cyclostoma tricarinata Say. Jour. Phila. Acad. Nat. Sci. I, 

 1817, 13; Valvata sincera Say, Rep. Long's Exped., II, 1824, 

 264, PL XV. 11 ; V. humeralis Say, New Harm. Diss. II, 1829, 

 244: V. virens Trvon, Proc. Phila. Acad. Nat. Sci., 1863, 148, 

 PL I, 11; V. humeralis californica Pilsbry, Xaut. XXII, 1908, 

 82; *V. humeralis Hannibal, \Y. Coast Shells. 1910, 316, PL 

 II, fi. 



Wider experience with this genus has caused the writer 

 to regard all the American Valvatas to he referrable to a single 

 polymorphic species, tricarinata of Say. This name is rather 

 a misnomer, however, since the species is only tricarinate in 

 waters surcharged with mineral salts; under normal conditions 

 it is smoothly rounded. 



Valvata, though common .enough sporadically in central 

 California, Nevada, and Colorado to the northward and in 

 Mexico to the south, has not been recorded from the present 

 area, where it is doubtless infrequent due to the absence of 

 extensive lakes to which it is almost wholly restricted. The 

 species occurs in the San Bernardino Mountains not far from 

 either System in Bear Lake and Bluff Lake Cienaga, hot these 

 helong to the Mojave System. 



All North America south to southern Mexico. 



::.-, 



