30 



very little oblique ; labium simple ;, umbilicus small, nearly con- 

 cealed by the base of the labium. 



Length rather more than one-tenth of an inch. Inhabits the 

 North-west Territory. 



The elevated lines on this shell give it a very handsome appear- 

 ance, and readily distinguish it from any of our native species 

 that I have seen. The European analogue is the aculeata of 

 Muller, but our shell is destitute of recurved points on the lamel- 

 liform lines. PI. 15, f. 1. 



H. PORCINA. — Shell depressed, yellowish brown ; epidermis 

 rugose, with minute, very numerous bristles ; whorls rather more 

 than four, depressed above, beneath rounded, forming a very 

 obtuse angle rather above the centre of the v»'horl ; umbilicus 

 open, lathei small, profound ; labium simple. 



Breadth rather more than three-tenths of an inch. Inhabits 

 Noith-west Territory. PI. 15, f. 2. 



H. FRATERNA. — Shell couvex, brownish horn color, minutely 

 hirsute ; whorls five, rounded ; umbilicus partially or entirely 

 closed by the termination of the labrum ; region of the umbilicus 

 indented ; aperture much contracted by the labrum ; labrum 

 reflected, white, unarmed ; its outer edge not projecting beyond 

 the curve of the whorl : its inferior angle extends to the centre of 

 the base of the shell ; labium with a strong, prominent, com- 

 pressed, white tooth. 



Breadth one-third of an inch. Inhabits Pennsylvania. 



I obtained a specimen of this shell several years ago, but sup- 

 posing it to be an accidental variety of the hirsuta, I laid it aside 

 without further notice. Since then, however, Messrs. Hyde and 

 Mason have pi'esented numerous specimens of the same species to 

 the Academy, having found it rather common ; I therefore no 

 longer hesitate to consider it as a distinct species. It resembles 

 Helix monodon of Mr. Backett (Tians. Linn. Soc. London, vol. 

 xiii., pi. 5,) in the confoimation of the aperture, but that shell is 

 represented as being largely umbilicated, and its labrum does not 

 extend near to the centre of the base, as it does in our shell. PI. 

 15, f. 3. 



11. DiODONTA. — Shell somewhat depressed ;. spire convex, very 

 little elevated ; whorls five, rounded, regularly, but not promi- 

 nently wrinkled, and grooved transversely ; aperture moderate ; 



