of the mouth, white, rather deeply and abruptly more ar- 

 quated at base. 



SYNONYMS. 



Helix albolabris. Nobis. Jim, Ed. of Nichols. En- 

 cycl. vol. iv. Feriissac, Hist. Nat. pi. 43, f. 1 to 5. 



Cochlea virginiana, subalbida, mediocris, circiter quinis 

 orbibus parum altis ad claviculam circumscripta. Lis- 

 ter Synops. pi. 47, f. 45. 



observations. 



This is one of our most common species, less abundant 

 however in the Western than the Eastern portion of the 

 United States ; and is an inhabitant of an extensive region, 

 extending from Canada to South Carolina whence an indi- 

 vidual was sent me by the late Mr. Elliott, and it is proba- 

 bly found even in Florida. It belongs to the genus Aca- 

 vus, Montfort, which he separates from Helix, in conse- 

 quence of being destitute of umbilicus.. 



A species of the Linnsean genus Acarus infests the ani- 

 mal. I have frequently seen this little active parasite, run- 

 ning out and in the respiratory cavity, when the orifice was 

 opened to receive the air. Sometimes it is excluded for a 

 few moments by the closing of the orifice, but it courses 

 nimbly about until another dilatation of the pulmonary ap- 

 erture, receives it into the interior. An analogous species 



FLATE XIII. 



