PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 331 
closely approximated smaller ridges upon which the posterior nodulous 
ridge grows with the whorl; the suture therefore is invisible and the 
deep channel above it only simulates a suture; on the base are two 
very strong spiral ridges, rather squarish, which run directly into the 
throat of the aperture; the pillar is twisted, especially in the young; 
it forms a small sharp emargination like that in some species of Bittium, 
the outer lip is simple except so far as modified by the sculpture; if 
the outer lip be broken away half a turn, two very strong sharp plice, 
transverse to the axis, appear on the pillar and continue up the spire, 
exactly as in Nerinea ; on the outside of the whorls there is little tran- 
verse sculpture except strong lines of growth; occasionally the stems 
of the “figs” are prolonged as pseudo-riblets in the interspaces. Lon. 
of shell, 8.5; of last whorl, 3.25; max. lat. of shell, 2.50™”. 
Habitat—Key West, rare, on the reefs at low water. 
This isaremarkable shell. It closely resembles Nerinea in many par- 
ticulars and externally is not unlike WN. trinodosa as figured by Chenu. 
It differs from Pyramidella, to which it is provisionally referred, in its 
strong spiral sculpture, small number of plice, and total absence of 
callosities. 
Odostomia impressa Say. 
Tampa, on oysters, abundant; also in similar situations at Cedar 
Keys and at Saint Augustine. <A variety(?) granatina occurs at Cedar 
Keys in which the posterior ribs are strongly nodulous, and the appear- 
ance thus rendered so different from the type as to suggest they are 
‘specifically distinct. 
Odostomia acutidens nv. s. 
Shell solid, rude, yellowish-white, acute, six-whorled, marked with 
lines of growth merely; suture evident, but not channeled; whorls 
rather flat, except the last, which has a neatly rounded base; aperture 
with the outer lip acute, rounded to the columella, which stands out from 
the surface of the shell, with a groove behind it, but no umbilicus; 
column with one large, very sharp tooth at right angles to the axis of 
the shell; space between the columella and posterior end of the outer 
lip polished, not callous. Lon. of shell, 4.12; of last whorl, 2.50; of 
aperture, 1.75; max. lat. of shell, 2.00™™. 
Habitat.—Cedar Keys, on the mud flats; not common. 
Parthenia cedrosa n.s. (Plate X, Fig. 11.) 
Shell slender, subeylindrical, whitish, thin, seven-whorled; nucleus 
sinistral, smooth, remainder except the base reticulated by equal, mod- 
erately strong plications, extending from suture to suture, but ceasing 
at the periphery of the base, about four to a millimeter, with lesser iter- 
spaces; underlaid and reticulated by revolving threads, about six on 
the side of the whorls, and as many more, but fainter, on the base; apex 
minute, blunt; base rounded; aperture as in Turbonilla, with thin 
