338 Remarks on Certain Species qf ' 



covered, and the striae are less prominent, especially at the 

 base, than in the Alabama shells. 



The measurement of an average sized specimen is : — 



Diam. maj. 17, min. 15, Alt. 10 mill. anfr. 5. 



Specimens from Tennessee, for which I am indebted to Mr. 

 Postell, are small, extremely thin and pellucid, with the umbi- 

 licus generally but little open, the last whorl obsoletely angu- 

 lated at the periphery. 



Diam. maj. 14, min. 12, Alt. 8 mill. anfr. 5. 



There is a variety figured by Mr. Shuttleworth (in the plates 

 referred to in my notes on H. Pennsylvania) as H. clausa Say, 

 var. subalbolahris. It is, I believe, the globose form, with 

 wider and less thickened lip, and more open umbilicus than in 

 the Illinois shell. I have a specimen about equal in size to 

 the largest one from Alabama, — it is pellucid, shining, and at 

 the base nearly smooth, but showing the fine spiral impressed 

 lines as distinctly as H. Mitchelliana. I received it from Ohio. 



In the cabinet of the Academy at Philadelphia, there are 

 three shells, understood to be those deposited by Say, labelled 

 H. clausa Say, with Ohio as habitat, in the hand- writing of Mr. 

 Phillips. These specimens agree pretty closely with Say's 

 description. 



The Alabama shells may be compared in general aspect, with 

 H. Pennsylvanica, and the others above mentioned with 77. 

 Mitchelliana. Say's figure is rather of the former, — his descrip- 

 tion and the figures of Dr. Binney of the latter forms. 



In the Boston Journal, Dr. Binney describes the umbilicus 

 as " nearly covered by the reflected lip," — probably he had not 

 then seen the imperforate II. Mitchelliana, as no reference is 

 made to it. 



He remarks in the " Terrestrial Mollusks," that the surface 

 of II. clausa is " shining and its striae of increase delicate and 

 regular," — also that " the umbilicus in specimens entirely ma- 

 ture is covered, but, as commonly seen, a small opening still 

 remains." It would seem that Dr. B. did not know the Alaba- 



