[79] 



Georgia, to Texas, Maryland, Eastern Pennsylvania, West- 

 ern New York. 



This species is allied closely to M. thyroMes : it differs in its 

 smaller size, more globular form, darker color and less open 

 umbilicus. It was first described as a far Southern species, but 

 has been recently ascertained to be common iq the Middle 

 States. A remarkable minor form of thyroides was described 

 by Mr. W. G. Binney several years ago, from the vicinity of 

 Philadelphia, and he declares his inability to distinguish it 

 from forms of bucculenta. This shell is really bucculenta, and 

 its identity was first pointed out by Dr. E. Michener, in the 

 American Journal of Conchology, 1865. It has also beea 

 noticed in New York by DeKay, who described it in his 

 Report under the name of Helix rvfa. In the neighborhood 

 of Philadelphia all the specimens of so-called thyroides that I 

 have seen are the true bucculenta. 



7. Mesodon devia, Gould. 



Plate 8, figure 3. 



Orbicularly depressed, rather thick, strongly obliquely 

 striate ; spire convex, suture moderately impressed ; whorls 65. 

 the last well rounded ; aperture obliquely and transversely 

 lunate, with a widely-reflexed white lip, which is somewhat 

 toothed at the base, and impinges on the open umbilicus ; 

 parietal tooth trigonal, oblique, quite large. Dark horn color,, 

 nearly brown. 



Diam. 20, height 11 mill. 



Oregon. 



Mesodon Columbiana. 



VARIETY DENTATA. 



Plate 8, figure 12. 



This, which will be described among the non-dentate species,, 

 sometimes developes a parietal tooth. Mr. Bland, several yearS' 

 ago, (Annals N. Y. Lyceum, vii.,) mentioned that his cabinet 

 contained a specimen with such a tooth. I have seen several 

 specimens of this variety, and my cabinet contains them from 

 three different localities. 



11* 



