[ 80 ] 



Jl Shell subangulate on the peripheri/. 

 8. Mesodon Roemeri, Pfeiffer. 



Plate 8, figure 4. 



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

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

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

 £>T 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 

 entij-ely closing it ; parietal wall generally armed with ,a well- 

 developed tooth. Horn-colored. ' 



Diam. 21, height 10 mill. Co*!'^-.'^ ^-^ 



' Texas. 



May be distinguished at once from all the other species ^y 

 its depressed form and angulate periphery. 



** Mt dentate. 



t Umbilicus closed. 



X Unicolored. 



9. Mesodon major, Biuney. 



Plate 8, figure 5. 



Ventricose, convex, globosely turbinate, heavy, covered with 

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

 pressed; whorls 6, convex, the body whorl very large and 

 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. ' Cx^- 



Tennessee to Florida and Alabama. 



Dr. Binney first described this as a species distinct from 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 and myself admit its 

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



