RissoA. 299 



tical with that, I shall not venture to claim for it any more remote 

 history than that u'iven by Colonel Totten. 



This shell is so plain as to present no striking mark of distinc- 

 tion, and it is consequently not easy to describe it. The only shell 

 liable to be confounded with it are the Odostomia fusca and O. hi- 

 suturalis ; a slight examination of the aperture readily solves any 

 doubt on this pohit. 



Rissoa latior. 



C'nnjula latior, IMighels and Adams, Bost. Journ. N. H. iv. 48, pi. 4, fig. 22 (1842). 

 liissoa latior, Stimpson, Shells of New England, 34 ; Check Lists, 4. 



Shell minute, ovate-conic, smooth, pale horn color ; whorls more 

 than four, convex ; suture much impressed ; last whorl 

 broad, larger than the rest of the shell ; aperture ovate- 

 orbicular, left margin with a lamina ; operculum horny. 

 Length, eight hundredths of an inch ; breadth, five hun- 

 drcdths oi an men ; divergence, sixty degrees. 



Casco Bay ; taken from the stomach of a haddock in the spring 

 of 1841. 



It is in the cabinet of J. W, Mighels. 



This species has a slight resemblance to R. mimda, Totten, in 

 the absence of sculpture ; but the spire is shorter, more pointed, 

 and its divergence is much greater, giving a very different form to 

 the shell. It is, moreover, a much smaller shell. It appears also 

 to be allied to Turbo rcticulaius, Montagu, but is distinct from that 

 species in not having as many turns by one and a half ; it differs, 

 also, in not being " strongly striate, both longitudinally and trans- 

 versely," and in not having the " aperture thickened by a rib." It 

 has been found very rarely, usually in company with R. carinata 

 and Cing-ula arenarius, Montagu {Mighels and Adams). 



Rissoa aculeus. 



Fig. 172. 



Shell minute, sub-cylindrical ; wlioris convex, covered with regular, micro- 

 scopic revolving lines ; aperture ovate ; umbilicus partial. 



Cingula aculeus, Gould, Inv. 1st ed. 2GG, fig. 172. -De Kat, N. Y. Moll. Ill, pi. 6, fig. 

 11."). 



Rissoa aculeus, Stimpson, Check Lists, 4. 



Shell minute, ovate-cylindrical, elongated, light yellowish horn 

 color ; whorls six, convex and separated by a deep sutural region ; 



