33 
(Say’s American Conchology, vol. i., No. 11, April, 1831.) 
Helix albolabris. — Shell convex, imperforated, immaculate, 
pale reddish brown ; volutions about five and a half, with rathei 
obtuse wrinkles, 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, Hobis — Hobis. Am. Ed. of Nichols. Encych, 
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 Western 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 Montfort^ 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 tooth, 
rather above the middle, and not very prominent. 
5 
