WEST MEXICAN MOLLUSCA. 169 



amined the animal taken from alcohol and found the jaw 

 of Limnea. 



Physa mexicana Philippi. 



Two specimens two-thirds the size of Say's type of P. 

 heterostrofha figured by Binney in Fresh Water Shells, 

 p. 84, seem to me to confirm identity of the species. 

 They are less similar to Haldeman's P. osculans from 

 Mexico. 



Planorbis liebmanni Dunker. 



Over 70 specimens from Mazatlan do not differ in form 

 or size from two Vera Cruz shells, whence the typical 

 form was described. They are much smaller than Gould's 

 P. gracilentus of the Colorado Desert, showing the same 

 difference as in the figures given by Binney in Fresh 

 Water Shells, p. io8. Binney says that the figure is en- 

 larged, but Gould gives it as half an inch wide or larger 

 than the figure, while the P. liebmanni is little over one- 

 quarter inch. It comes nearer P. havanensis, which 

 Pfeiffer says (1. c, p. 107) was found in Texas also, by 

 Roemer. On p. 108, Roemer is quoted for only P. lieb- 

 manni from Texas, showing some confusion of the spe 

 cies. 



Calyculina partumeia Say, var. truncata Linsley. 



One specimen from Tepic seems to agree better with 

 this form than with an}^ other, but is even flatter in pro- 

 portion and smaller than usual, showing that those char- 

 acters are not confined to the most northern shells, while 

 the opposite extremes as found in lenticula are not exclu- 

 sively western. It measures 0.27 inch long, 0.23 high, 

 and 0.13 in diameter. 



The only calyculate species described by Prime from 

 Mexico is S^hceriuni siibtransversttm from Tabasco, and 

 differs in very small size, more elongation and other 

 characters. The size is given by Prime as length 0.30 

 inch, height 0.20, diameter o.io. 



