1920.] 



NATURAL SCIENCES OF PHILADELPHIA. 



193 



Laguna de Chapala, State of Jalisco, collected by Prof. Francisco 

 Contreras, March 1, 1920. Type No. 46,194. 



Fig. 1. — Planorhis tenuis chapalensis. Enlarged. 

 Planorbis contrerasi new species, Fig. 2, 



The shell is solid; last whorl compressed on the right side, bluntly 

 angular, with funnel- or vortex-shaped umbilicus; left side angular, 

 with rather wide bowl-shaped concavity. Surface closely striate 

 spirally within both concavities, seemingly with weak traces of spiral 

 lines over the peripheral part, though the specimens are all so wave- 

 worn that the external sculpture cannot be seen except within the 

 aperture. The aperture is narrow, angular at the ends. 



Greatest diameter 14.3, alt. at aperture 10.2 mm.; fully 4 whorls. 



^ c>} 



. Fig. 2. — Planorhis contrerasi. Enlarged. 



Laguna de Chapala, State of Jalisco, collected by Prof. Francisco 

 Contreras, March 1, 1920. Type No. 46,193. 



While the shape is somewhat like that of Planorhis tejiuis exag- 

 geratus, of Lake Patzcuaro, this species differs by its solidity and 

 especially by the strongly developed spiral sculpture. It is a very 

 distinct species. 



Physa solidissima Pils. 



Laguna de Chapala. Dead specimens of this remarkably globose, 

 heavy species are somewhat larger than the type, the largest measur- 

 ing: length 11.3, diam. 9.5, length of aperture 9.9 mm. The rounded 

 fold of the massive columella is prominent, as in the type. 



It is hoped that living individuals can be secured. They may 

 show differences from the ordinary Physas. 



Anodontites jaliscoensis n. sp. Fig. .3. 



The shell is oblong, the alt. 55 per cent, of the length, the diam- 

 eter slightly less than one-third the length, moderately solid ; Isabella 



