IXGERSOLL ON ROCKY MOUNTAIN MOLLUSKS. 133 



Two large lots in alcohol. All are more or less damaged, as is solikelj' 

 to be the case under the circumstances ; but they seem to be of this 

 species, which to my knowledge, has not been reported heretofore from 

 the West. They vary much in appearance, some being almost exact 

 miniatures of P. Lordi and P. ancillaria. But they seem to coincide in 

 the points of P. Sayii more nearly than in those of any other of the very 

 confused species of this variable genus. 



Physa heterostropha, Say. 



Localities : Canon City, Col. ; Empire, Col. ; Hot Sulphur Springs, 

 Middle Park, Col. 



Some specimens from pools near Denver, which are small, horn-colored, 

 and streaked across the whorls with white, resemble closely the descrip- 

 tions and figures of P. virgata, but as I have no specimens of that species 

 to compare them with, I hesitate to identify them as such. 



Planorbis ammon, Gould. 



Localities: Utah Lake, Utah ; Spring Lake, Utah. 



This splendid shell, of which many fine specimens are at hand, seems 

 pretty well distributed west of the Eocky Mountains, having been found 

 on the Pacific slope and in several of the interior Territories. 



Gyrauliis parvus, Say. 

 Localities : Davidson's Ranch, Boulder Co., Col. ; Utah Lake, Utah. 

 Found everywhere among the mountains of the West. 



TALVATID.E. 



Valvata tricarinata, Say. 



Locality : Utah Lake, Utah. 



The degree of carination among these specimens, all of which are of 

 small size, and in a semi-fossil condition, varies greatly, and it would not 

 be difficult to assign some of them to V. sincera, but it would be hard to 

 draw any line of demarcation between such and the truly tricarinated 

 specimens. 



RISSOID.B. 



Fluminicola fusca, Haldeman. 

 Locality : Utah Lake, Utah. 

 Semi-fossil, on a mud flat. 



Conchifera. 



UNIONID.E. 



Anodonta oregonensis, Lea. 



Locality : Utah J^ake, Utah. 



Many specimens living. 



[Found very abundantly and of good size in the brackish water at the 

 Southern extremity of Utah Lake in the soft mud. Occasionally eaten 

 by the inhabitants, who sometimes declare them •' better than oysters.'' 

 They are also to be seen displayed for sale in the markets of Salt Lake 

 City. I was several times told of another clam with heavy shells, found 



