52 Hemarlis on Certain Species of 



from Columbns, Ohio ; indeed it is sliown in the figure of the 

 latter in Terr. Moll. pi. 10. I have noticed it moderately 

 developed in specimens of II. albolabris from Ohio and Mas- 

 sachusetts. 



I learn from Dr. Leidy that he has not examined the animal 

 of ^. major. II. major and 11. albolabris are in fact subject to 

 much variation in size, color, texture, sculpture, form of aper- 

 ture, and lip, and development of the latter, but there are no 

 constant characters in either to justify their separation as distinct 

 species. In my cabinet are specimens which I refer to H. 

 major., from Florida, Georgia, Tennessee, and South Carolina, 

 forms which seem to be intermediate from Alabama, Missouri, 

 and Wisconsin, — and of II. albolabris from most of the Eastern, 

 Middle, and Western States, as well as from Virginia, North 

 Carolina, and Canada West. 



The following are measurements of varieties of II. major, — 



Diam.maj. 35, min. 30, Alt. 23, mill, (globose), Florida. 



" Georgia. 

 {depressed), " 

 (flattened), " 

 (elevated), " 

 (depressed), Wisconsin. 

 " Missouri. 



The two latter I call intermediate forms — the following H. 

 albolabris, — 



Diam. maj. 35, min. 30, Alt. 19, mill. Is". Carolina. 



" " 32, " 26, " 15, " Ohio. 

 " " 28, " 24, " 15, " Canada West. 

 " " 26, " 21, " 12, " Pennsylvania. 

 " " 23, " 19, " 11, " Tennessee. 



I possess two specimens of the above mentioned Wisconsin 

 shell. Both have a remarkably thick and dark-colored epider- 

 mis, the tooth-like process on the lip near the umbilicus very 



