SUBALPINE MOLLUSCA. 65 



Stripes often observed in specimens from alkaline or 

 brackish water near the coast. 



12. Physa blandi Lea. This common Sierra spe- 

 cies was obtained 12 miles east of Columbia at 3,000 feet, 

 and also near Mono Lake on the east slope. The latter 

 are large, but as usual with this species have the spire 

 eroded, though perfect in the young. 



13. Planorbis. See Dr. Cooper's notes. 



14. Gyraulus vermicularis Gould. Common at 

 the two localities, and everywhere from the east base of 

 the Sierra to the coast of California north of latitude 37-, 

 as far north as Vancouver's Island. 



15. Gyraulus parvus Say. Three specimens only 

 were found, the iirst reported in California, and not 

 known from Nevada except as a fossil, though found in 

 Utah and Colorado up to 9,300 feet. 



16. Gyraulus parvus elevatus C. B. Adams. 

 Thirtv specimens found onlv on the west slope at Lake 

 Eleanor differ constantly from Say's species, agreeing 

 with Adams' shell, which has only been before reported 

 from the Northeastern States. There seems to be no lo- 

 cal cause for the variation. (See Binney's Pulm. Lim- 

 noph., p. 134, 1865.) 



17. Ancylus. See Dr. Cooper's notes. 



18. Sph^rium. See Dr. Cooper's notes. 



19. PisiDiUM ABDiTUM Prime. This species was abun- 

 dant, but only on the west slope below 5,300 feet, and 

 was found also by Carlton at 6,240 feet in Truckee Riv- 

 er on the east slope ; also by Ingersoll up to 9,300 feet in 

 Colorado, extending throughout the Eastern States north 

 of 35^ latitude, under several varieties. Prime has given 

 fifteen names as synonyms of this polymorphous shell, all 

 being connected by intermediate forms, and though he 

 retained P. occidcJita/c as distinct when first discovered. 



