INVERTEBRATES. 351 



GASTEROPODA. 



Genus PLEUROTOMARIA,. Defrance, 1826. 



(Diet. Sci. Nat., xli, p. 381.) 



Pleurotomaria subconstricta, M. and W. 



PL 28, figs. 6 a, 6 6, 6 c. 



Pleurotomaria subconstricta. Meek and WoaTHEN, Oct., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 458. 



Shell small, conical-subovate, longer than wide ; spire mod- 

 erately elevated. Volutions five and a half to six, obliquely 

 flattened or concave above, excepting near the suture, where 

 there is a subangular prominence occupied by a series of small 

 folds or nodes. Body whorl forming rather more than half the 

 entire length, biangular around the middle, the lower angle 

 being less prominent and more obtuse than the other, and not 

 exposed on the 'spire, while the other passes around near the 

 middle of each upper turn; between the two angles, the middle 

 of the body volution is vertically flattened, or a little concave, 

 while its under side is convex. Suture linear, but occupying 

 a rather distinct, somewhat rounded constriction or depression. 

 Aperture broad, subovate, or subcircular. Columella rather 

 arcuate, not perforated. Surface ornamented by about fifteen 

 revolving lines, some ten or twelve of which occupy the under 

 side of the body whorl, where they are larger than above; 

 crossing all these lines, are extremely fine, closely arranged 

 transverse striae, which, on the under part of the body turn, 

 show a tendency to cluster into small, regular wrinkles. Spiral 

 band narrow, flat, and located just above the middle angle. 

 Length, 0.33 inch; breadth, 0.24 inch; apical angle nearly 

 regular; divergence, 65°. 



As near as we have been able to determine from a brief written description, 

 unaccompanied by figures, this species would seem to be related to P. Prout- 



