16 



LAND AND FRESH- WATER SHELLS OF N. A. [fART HL 



Family YIVIPARID^E. 



Lingual membrane with seven series of teetli (3, 1, 3), the 

 central teeth broader ; simple or denticulated at their apices. 



Fig. 22. 



Lingual dentition of Vivipara suhpurptirea (Stimpson). 



Rostrum simple, moderate ; tentacles short, stout, the right 

 hand one, on the male, as large as the rostrum ; eyes on 

 peduncles at their exterior base. Foot large, simple. Oper- 

 culum annular, sometimes with a spiral nucleus. Shell 

 spiral, turbinate, covered v/ith an olivaceous epidermis; 

 aperture simple in front. 



TITIPARA, Lamarck. 



Foot of moderate size, thick, not produced beyond the snout. 

 Colors very dark. Head rather large. Snout of moderate 



Fig. 23. 



Fig. 24. 



Animal of V. intertexta. (Male.) 



Lingual dentition of V. intertexta. 



size. Lingual teeth armed with large denticles at their cusps ; 

 the central tooth with from seven (swamsonii) to eighteen (si/b- 



