CERITHIOPSIS. 389 



Cerithiopsis terebralis. 



Fig. 181. 



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

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

 canal very short. 



Cerithinm terd>ra!e, Adxms, Bost. Joiirn. Nat. Hist. iii. pi. 3, fig. 7. — Gould, Inv. 1st 



cd. 276, fig. 181 

 Cerithiopsis terebralis, Stimpson, Check Lists, 5. 



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

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

 dish-brown, with occasionally a whitish revolving 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 

 cliccked with crowded, minute, longitudinal lines, none of 

 which cross the summits of the ridges. On the lower ^ 'Y/,^>-a' 

 whorl arc 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 C. Emersonii. Its size and pro- 

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

 It is at once known by the prominent ridges, which resemltle the 

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

 C. Einrrsonii, 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. (^Slimpsoii.y 



Family CANCELLARIID^. 



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

 canal, directed upwards. 



