94 Bryant Walker 



Lymn.-T'A coopuri Hannibal. 



Lymncea Cooperi Hannibal, Proc. Mai. Soc. Lond., X, 1912, p. 143, pi. VI, 



fig. 13a — c. 

 Type locality: v^pring at Wright's, Santa Cruz ^Mountains, Cal. 



Lymn.^a montanknsis Baker. 



Lymncea montanensis Baker, Naut., XXVI, 19 13, p. 115. 

 Type locality: Hayes' Creek, Ward, Montana. 



Family PLANORBIDtE. 



Subfamily PLANORBIN^ H. and A. Adams, 1858. 



Genus PLANORBIS Miiller, 1774. 

 Dr. Dall (32. p. 80) has proposed the following arrangement of this 

 genus : 



Subgenus Planorhis s. s. 

 Type Planorhis corncus Miiller. 



Section Planorbina Haldeman. 

 Type P. olivaceus Spix. 



Subgenus Hclisoina Swainson. 

 Type P. bicarinatiis (Say) Sowerby. 



Section Picrosonia Dall. 

 Type P. trivolvis Say. 



Section Planorhella Haldeman. 

 Type P. campamilafits Say. 



Subgenus Tropidiscus Stein. 

 Type P. itmhilicatiis Miiller. 



Subgenus Hippeittis Agassiz. 

 Type P. fontanus Lightfoot. 



Section Menctus H. and A. Adams. 

 Type P. opercularis Gould. 



Subgenus Gyranlus Agassiz. 

 Type P. albus Altiller. 



Section Torqiiis Dall. 

 Type P. parvus Say. 



Section Annigcr Hartmann. 

 Type P. crista L. 



For a criticism of Dall's arrangement, see Kennard (64, p. 47) and 

 reply by Dall (33, p. 141). 



Brown and Pilsbry have proposed (15, p. 212) a new section, Trop- 

 icorhis, type P. licbiiianiu Dkr., but without any definition. 



