MUSEUM OF COMPARATIVE ZOOLOGY. 337 



range, will tell the story quite as well as the large ones, if not better, as the 

 small species, not living too close to the beach, have a wider average geographi- 

 cal range than the large ones from any depth of water. The present species 

 affords an excellent example of this rule, and a study of its variations is most 

 instructive. 



The figure of the soft parts of this species which appears herewith is from 

 the unpublished manuscript of Dr. Wm. Stimpson, who observed it at Charles- 

 ton, S. C; and collected specimens in Massachusetts Bay. The Chemnitzia 

 speira of Eavenel figured by Holmes in his Post Pliocene Fossils of South Car- 

 olina (p. 82, pi. xiii. figs. 1, 1 a) is with little doubt a synonym of interrupta. 

 The species figured by Holmes as interrupta is, however, probably something 

 else. 



Turbonilla curta n. a. 



Plate XXVI. Fig. 7 c 



Shell waxen white, acute, with nine or ten rather inflated whorls ; nucleus 

 inflated, globose, sinistral, polished, mostly immersed ; remaining whorls sculp- 

 tured with (on the last whorl) about twenty-five close-set rounded ribs, extend- 

 ing from suture to suture, and but little % curved; also a few faint lines of 

 growth; no spiral sculpture; base smooth, except for a few lines of growth; 

 general surface polished; aperture subquadrate; pillar slender with a faint 

 spiral ridge; suture very distinct. Lon. of shell, 8.3; of last whorl, 2.9; max. 

 lat. of shell, 2.75 mm. 



Habitat. Yucatan Strait, 640 fms. Off Hatteras, in 15-124 fms., sand, 

 temperature 61° F.; U. S. Fish Commission. 



This shell may not be perfectly mature, but in any case is unusually short 

 for its breadth. The figure appears slightly less acute than the shell itself, 

 and the anterior prolongation of the aperture is due to a fracture. It differs 

 from all the species figured by Orbigny, Jeffreys, Watson, and Verrill, and I 

 cannot identify it with any of the unfigured species of this puzzling group. 



The ridge or plica on the pillar is undoubtedly variable among individuals 

 in some, if not all, of the species of this group. When apparently absent near 

 the mouth it can usually be found on the pillar of the more apical whorls. 



Turbonilla pusilla C. B. Adams. 

 Chemnitzia pusilla Adams, Contr. Conch., p. 74, 1852. 



Habitat. Barbados, in 100 fms. Jamaica, Adams. Northward to the 

 vicinity of Cape Hatteras, N. C, in 15-63 fms., sand, U. S. Fish Commission. 



A single well preserved specimen of this species was obtained from the 

 Blake collection. It seems to be rather rare everywhere. 



vol. xviii. 22 



