286 H. C. Lea’s Description of 
part are confined the coste and sulcus, and it presents the 
appearance of a secondary shell.  Anteriorly, its margin 1s 
sinuous, which causes a similar bending of the ribs. The 
rest of the shell is nearly smooth, very thin, and diaphanous. 
This curious little species I found among some shells sent 
to my father many years since, from South Carolina. It has 
not the most distant relationship to any of its congeners as 
yet described in this country. Although it might seem to 
be an immature shell, from its small size and extreme thin- 
ness, yet, from the peculiarity of its growth, being centrally 
incrassated from the outside, I am inclined to think that it 
had reached its full period. - 
Borta sretacata. PI. XXVI. Fig.2. Proceed. Bost. Soc. 
Nat. Hist., l. c. 
. B. testa cylindrica, sub-quadrata, renal albidá, polita, eburned ; os 
oceultà ; anfractu ultimo superné calloso, inferné striis transversis parvis; 
apertura superné arctata, inferné ovatà; columella plico magno et pues 
ell cylindrical, sub-quadrate, thick, whitish, polished, 
ivory-like; spire concealed; last whorl with a callus above, 
and small transverse striæ below; mouth narrow above, ovate 
below ; columella with a large and a small fold. Long. 15. 
Lat. .07 poll. 
Hab. Shore of New Jersey, near Cape May. 
Remarks. The stri on the base are small and insignifi- 
cant. "The columella has a large oblique fold, about —- 
fourth the length of the shell.from the base; below aro 
takes an undulation, scarcely deserving the name of a su 
and descends suddenly to join the outer lip. The colume 
is continuous posteriorly, and, above, it widens out into 3 
callus at the region of the spire, where it turns round, 
is produced into the outer lip. The substance of the shell . 
is thick, smooth, and ivory-like. — . e : 
There is no danger of confounding this little shell with any 
of the genus in the United States. The two folds at onc? 
listinguish it, and it is the only species with an occulied i 
and plicate columella. - | T 
w 
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