28 Remar'ks on Certain Species of 



the reflected lip, depressed rather than subglobular ; the shell 

 as strongly striate above and below, as II. Pennsylvanica. 



I add the measurements of the largest and smallest indivi- 

 duals : 



Diam. maj. 18, min. 15, Alt. 10 mill. anfr. 6. 

 " " 12, " 10, " 7 " " 5. 



A specimen from Iowa is very similar to those from Alabama. 



From Wisconsin, Missouri, Illinois, and Kentucky, I have 

 forms which agree closely with Say's description, — in these the 

 reflected lip is less thickened, the aperture is more round, the 

 last whorl being more globose, — the umbilicus is more nearly 

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

 base, than in the Alabama shehs. 



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 miU. anfr. 5. 



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

 referred to in my notes on II. Pennsylvanica) as II. clausa /Say, 

 var. siibalbolabris. 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 II. 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 

 II. 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 



