26 VIVIPARA. 



Length 32, diam. 20 mill. 



Ohio, Michigan, Western New York. 



This species much resembles a half-grown 

 ponderosa, but is more regularly oval in its 

 outline and of lighter texture. There is no 

 doubt of its being perfectly adult, and it is, I 

 believe, a very good species, with characters 

 intermediate between V. ponderosa and V. In- 

 tegra. 



^*jj. Shell geniculate. 



14. VIVIPARA GENICULA, Conrad. 



Hald., p. 15, t. 5. 



This species is very widely distributed in 

 the far southern States, and seems nearly to 

 replace V Integra and decisa. Mr. W. G. 

 Binney suggests that it is a deformed decisa, 

 but I have seen numerous specimens from 

 many localities, and they present a uniformity 

 of appearance that can be due to nothing less 

 than specific fcn:ce. 



(52) 



