33 



(Say's Americnn Conchology, vol. i., No. II, April, 1831.) 



Helix albolabris. — Shell convex, imperforated, immaculate, 

 pale reddish brown ; volutions about five and a half, with rather 

 obtuse wrinliles, crossed by very minute lines, more obvious on 

 the body whorl than on the spire ; suture distinct, not very deeply 

 impressed ; labrum abruptly contracting the mouth, rather widely 

 and abruptly reflected, flattened in the plane of the mouth, white, 

 rather deeply and abruptly more arquated at base. Plate 13, 

 fig. a. 



Synonyms. 



Helix albolabris. Nobis — Nobis. Am. Ed. of Nichols. Encycl., 

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



Cochlea virginiana, subalbida, mediocris. circiter quinis orbibus, 

 parum altis ad claviculam circumscripta. Lister, Synops. pi. 47, 

 f. 45. 



This is one of our most common species, less abundant, however, 

 in the ^\''estern than in the Eastern portion of the United States ; 

 and is an inhabitant of an extensive region, extending from 

 Canada to South Carolina, whence an individual was sent me by 

 the late Mr. Elliott ; and it is probably found even in Florida. It 

 belongs to the genus Acavus, Mont fort, which he separates from 

 Helix, in consequence of being destitute of umbilicus. 



A species of the Linnaean Genus Acarus infests the animal. I 

 have frequently seen this little active parasite, running out and in 

 the respiratory cavity, when the orifice was open 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 aperture receives it into the interior. An 

 analogous species inhabits the Helix nemoralis, L. of Europe, 

 according to Kirby and Spence. 



H. THYROIDUS. — Shell rather thin, convex, umbilicate, pale 

 reddish brown, immaculate ; volutions five, wrinkled ; suture 

 distinct, but not very deeply impressed ; labrum abruptly con- 

 tracting the aperture, rather widely reflected, flattened in the 

 plane of the mouth, excepting the superior third, and -white ; 

 umbilicus narrow, distinct ; labium with an oblique white tofith, 

 rather above the middle, and not very prominent, 

 5 



