A ^» d 
* 
O the United States. 437 
—— Férussac. Hist. Nat. des Moll. Pl. vxxix., 
fig. 1. 
. DESCRIPTION. 
Animal. Whitish, transparent, thread-like. 
Shell. - Discoidal ; epidermis greenish ; whorls 
about four, visible on the base of the shell as well as 
above, with numerous, equidistant, parallel, raised 
lines revolving upon them ; suture much impressed ; 
aperture semilunate, narrow, not expanding; lip 
thin; wmbilicus wide, forming a concave depression 
of the base, each volution visible to the apex ; within 
the aperture, on the external circumference, are 
placed two pairs of minute, conical, white teeth, the 
first pair in sight when losing into the — the 
other more remote. — 
Greatest transverse diameter one eighth of an inch, 
usually less. — 
GEOGRAPHICAL. DISTRIBUTION. Inhabits the New 
England States and — Common in vër- 
mont. .- 
Remarks. This eae shell is distinguished 5 
its discoidal form, greenish color, the fine revolving 
lines upon its whorls, and the singular teeth which 
are placed in the interior of the outer whorl. ‘These 
teeth are arranged in pairs on the external side of the 
parietes of the cavity, one of each pair being on the 
superior and one on the inferior part of the whorl. 
They are prominent, white, and conical, and may be 
discovered through the semi-transparent shell. One 
pair is so near the aperture as easily to be seen on 
looking into it ; the other — nearly one half a 
VOL. III. — NO. IV. 
