298 PYRAMIDELLID^R. 



front, moderately pointed behind, carrying on its simple 

 upper lobe a small, corneous, striated, elliptical or suboval 

 operculum. ]3ranchial plume ? 



" This animal, like all its congeners, is lively, permitting a 

 good examination of the organs. The individual examined, 

 is the variety with the subrotund volutions, and is of larger 

 growth than its congener with the more slender, subcylin- 

 drical contour, and flat, angular sutures, which may be 

 distinct : we have not met with one alive. The aspect of 

 this species differs from all the preceding. As to the shell 

 it appears to be a complete Chemnitzia., with the exception 

 of the pillar tooth, and there is no appreciable character in 

 the animal to account for its presence in the shell. The 

 animal is absolutely the same as that of Chemnitzia, 

 allowing for the slight, scarcely specific variation of a 

 little more or less long foot, muzzle, and tentacula." — 

 (Clark MSS.). 



Although the ordinary form of Ch. indistincta in which 

 the whorls are somewhat swollen at their bases, and the 

 ribs are very narrow, densely disposed, and flexuous (pro- 

 duced S-shaped), may easily be distinguished from the 

 present species, the coarse and straighter ribbed variety of 

 that shell bears so striking a resemblance to it, that were 

 it not for its want of the tooth-like fold, it would be 

 almost impossible to separate worn examples of the two 

 from each other. The most constant difference appears to 

 be that in the latter, — the intervals of the ribs on the 

 lower portion of each volution are crossed by several 

 spiral raised lines. 



This is one of the comparatively common species of 

 Odostomia, and is obtained from very many localities ; it 

 seems indeed so generally diffused that to specify localities 

 would be superfluous : it frequents shallower water than 

 most of its conoeners. 



