VIVIPARA. 29 



17. VIVIPAKA SUBSOLIDA, Antliony. 

 Plate 12, figs. 1, 2. 



Shell very thick, imperforate, ovate-elong- 

 ate, spire much elevated, composed of 6 — 7 

 convex whorls flattened somewhat superiorly ; 

 aperture broadly ovate, about one-third the 

 total length of ^he shell, parietal wall with a 

 heavy callous deposit. 



Length 50, diam. 27 mill. 



Illinois, Iowa. 



This is the most ponderous species of the 

 genus, being far heavier than F. ponderosa. 

 It is sufficiently distinguished by its elevated 

 spire and proportionally small aperture. Fig. 

 2 represents a young specimen. 



18. VIVIPARA INCRASSATA, Lea. 



Plate 15, fig. 7, and Plate 14, fig. 6 (decapitata, Anth.) 



Shell smooth, decorticated, thin, imperforate, 

 aperture small, oval, the parietal wall much 



(55) 



