THE MOLLUSCA OF COLORADO 63 



The species has been known in Colorado from two or three localities, but only a few 

 specimens had been seen until a fine colony was found on the St. Vrain, three miles west 

 of Longmont (Spangler). He collected several hundred without any difficulty. The 

 specimens are all rather small, but seem otherwise typical. 



Genus ANCYLUS Geoffroy 

 Ancylus rivularis Say. 



The records of A. caurinus in Part II of this catalogue, based upon identification by 

 Dr. Bartsch, should be eliminated. The specimens have been submitted to Mr. Bryant 

 Walker, who pronounces them A. rivularis, which I believe to be correct, and it avoids 

 a serious difficulty as to distribution. A single dead specimen recorded from Kjemmling 

 long ago by Professor Cockerell (Nautilus, Vol. Ill, p. 21) as "probably Ancylus caurinus" 

 likely belongs here. It is also likely that the Colorado records of fragilis and parallelus 

 belong here. 



Genus PHYSA Draparnaud 

 Physa gyrina Say 



Saguache County (Cockerell) ; mouth of Sand Creek on Bear River in Routt County 

 (Warren); Kremmling, Sulphur Springs, Steamboat Springs and southwest corner of 

 North Park (Henderson). This is the most generally distributed Physa of Colorado. 

 Long ago recorded from Eagle County by Professor Cockerell {Nautilus, Vol. Ill, p. 21) but 

 the record inadvertently omitted from Part II of this catalogue. Professor Cockerell's 

 suggestion, however, that this species is "generally replaced in this region by P. hetero- 

 stropha," is not in accordance with recent notions of the distribution of the two species. 

 Probably P. helerostropha and P. lordi should both be eliminated from our Colorado 

 faunal list. 



Physa walkeri Crandall. 



Specimens from a pond on Fossil Ridge, south of Ft. Collins, were thus identified by 

 Dr. Frank C. Baker. 



Genus APLEXA Fleming 

 Aplexa hypnorum Linn. 



I found a single specimen at Buford, Rio Blanco County. 



Genus VALVATA Miiller 

 Valvata sincera Say. 



Valvata lewisi was included in Part II of this catalogue because of Dall's definite 

 inclusion of Colorado within its range, and because he cut sincera out of the United States 

 I placed Ingersoll's record of sincera for San Luis Valley under lewisi. It seems to me 

 now that Dr. Dall was probably in error concerning these species. At any rate, I found 

 V. sincera abundant in a small pond on Marvine Creek, Rio Blanco County, and consider 

 it much safer to believe that Ingersoll's record was correct. Mr. Bryant Walker has 

 confirmed the identification of the Marvine specimens. 



