CERITHIOPSIS. 389 



Cerithiopsis terebrans. 



Fig. 181. 



Shell conic-tuiToted ; whorls ten, flattened, having three sharp, elevated, revolv- 

 ing ridges on each, with numerous line, longitudinal lines between the ridges ; 

 canal very short. 



Cerithiitm terebrale, Adams, Best. Joiirn. Nat. Hist. iii. pi. 3, fig. 7. — Gould, Inv. 1st 



ed. 276. i\ix. 181 

 Cerilhiopsis tenbrtUis, Stimpson, Check Lists, 5. 



Shell small, elongated-conic, composed of ten or twelve flattened 

 whorls, separated by a slightly excavated sutural region ; color red- 

 dish-brown, with occasionally a whitish revolvhig band at 

 the lower part of each whorl. On each whorl are three 

 elevated, compressed, revolving ridges, at about equal dis- 

 tances from each other, and perhaps we may reckon a 

 fourth, very small and bordering on the suture. The 

 spaces between the ridges are regularly rounded out, and 

 checlved with crowded, minute, longitudinal lines, none of 

 which cross the summits of the rido'es. On the lower c. urfbra- 

 whorl are two additional ridges. The base of the shell is 

 abrupt ; the canal very short and small ; the aperture oval, about 

 one eighth the length of the shell. Length, half an inch ; breadth, 

 one eighth of an inch ; divergence, twenty degrees. 



Found by Mr. C. F. Shiverick, at New Bedford, and in its vicin- 

 ity, below low-water mark. 



This species is closely allied to 0. Emersonii. Its size and pro- 

 portions are the same ; but it can scarcely be regarded as a variety. 

 It is at once known liy the prominent ridges, which resemble the 

 threads of a screw. There is nothing like the nodulous surface of 

 C. Emersonii^ and the minute barring between the ridges is a strik- 

 ing arrangement, to which there is no approach in that shell. 



[Animal whitish, front with broad white patches ; tentacles whit- 

 ish maculate ; a white line continued from back on each side of 

 neck. {Stimpson.^ 



FA.AIILY CANCELLARIID^. 



Shell with a short, ascending canal, or an oblique notch, or semi- 

 canal, directed upwards. 



