[80] 

 XI Shell suhangulate on the periphery. 



8. Mesodon Roemeri, Pfeiffer. 



Plate 8, figure 4. 



Shell depressed, rather thin, semi-transparent, closely, but 

 faintly striate; spire a little elevated, suture slightly im- 

 pressed ; whorls 5, somewhat convex, the last one subcarinate 

 or angulate on the periphery, scarcely descending to the 

 aperture ; aperture obliquely lunate, the lip well thickened, 

 but hardly expanded above, though becoming towards the 

 base well-reflected, covering partially the umbilicus, and rarely 

 entirely closing if; parietal wall generally armed with a well- 

 developed tooth. Horn-colored. 



Diam. 21, height IQ mill. 



Texas. 



May be distinguished at once from all the oiher species by 

 its depressed form and angulate periphery. 



** Not dentate. 



f Umbilicus closed. 



{ Unicolored. 



9. Mesodon major, Binney. 



Plate 8, figure 5. 



Ventricose, convex, globosely turbinate, heavy, covered with 

 coarse oblique striae ; spire, elevated, convex, suture well im- 

 pressed; whorls 6, convexj the body whorl very large aud 

 subglobular, very slightly declining ; aperture small, rounded 

 lunate, lip thick, moderately wide, with a tooth-like elevation 

 at the base near the body whorl, dilated and covering the um- 

 bilicus. Yellowish brown. 



Diam. 44, height 33 mill. 



Tennessee to Florida and Alabama. 



Dr. Binney first described this as a species distinct froni M. 

 alholahris, and separated it on account of its larger size, more 

 globose, elevated form, rounder aperture, coarser stri», &c. 

 Messrs. W. G. Binney, Newcomb, Gould arid myself admit its 

 validity, but Mr. Bland, on the contrary, unites the two. 



