APPENDIX. 257 



2. H. porcina. Shell depressed, yellowish-brown ; epi- 

 dermis rugose, with minute, very numerous bristles; 

 tvhorls rather more than four, depressed above, beneath 

 rounded, forming a very obtuse angle rather above the 

 centre of the whorl ; umbilicus open, rather small, pro- 

 found; labrum Simple. 



Breadth rather more than three-tenths of an inch. 

 Inhabits North-west Territory. PI. 15, fig. 2, 



3. W. fraterna. Shell convex, brownish-horn colour, 

 minutely hirsute ; ivhorls five, rounded ; imibilicus pai'- 

 tially or entirely closed by the termination of the labrum ; 

 region of the umbilicus indented ; aperture much contract- 

 ed 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, oblique, com- 

 pressed, white tooth. 



Breadth one-third of an inch. 



Inhabits Pennsylvania. 



I obtained a specimen of this shell several years ago, 

 but supposing it to be an accidental variety of the hirsuta^ 

 I laid it aside without further notice. Since then, how- 

 ever, Messrs. Hyde and Mason have presented 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 mono- 

 don of Mr. Racket, (Trans. Linn. Soc. Lond. vol. 13, pi. 5,) 

 in the conformation of the aperture, but that shell is repre- 

 sented as being largely umbilicated, and its labrum does 

 not extend near to the centre of the base, as it does in our 

 species. PI. 15, fig. 3. 



4. H. diodonta. Shell somewhat depressed ; spire con- 

 vex, very little elevated; ivhorls five, rounded, regularly 



