FAMILY PURPURIDiE — TRICHOTROPIS. 137 



GENUS TRICHOTROPIS. Broderip and Sowerby. 



Shell turbinate, thin, ventricose, keeled and umbilicate. Aperture longer than the spire, 

 compressed into a partial canal beneath : outer lip thin, sharp. Epidermis horny, produced 

 into long hairs at the angles of the shell. Opercle horny, with the nucleus lateral. Animal 

 undescribed. 



TRICHOTROPIS BOREALIS. 



PLATE VHI. FIG. 178. a b. 



TrkliotTopis borealis. Sowerby, Zool. Jour. Lond. Vol. 4, p. 373, pi. 9, figs. G, 7. 



T. costillatus COUTHOUY, Bost. Jour. Nat Hist. Vol. 2, p. 108, pi. 3, fig. 2. 



T. borealis. Gould, Inverlebr^ta of Mass. p. 300, fig. 207. 



Description. Shell ovate, acutely turreted. Whorls si.\: (four according to Dr. Gould), 

 separated by a deeply channelled suture ; the last whorl larger than all the others, with two 

 to four prominent revolving ribs with intermediate striae ; the two largest ribs only continued 

 on the upper whorls, which are thereby angulated : numerous minute vertical strias. Aper- 

 ture oblong-oval, rounded and broad above : lip thin, acute, distinctly indented, and festooned 

 by the ribs. Columella arcuated with a slight projection near its lower third, and abruptly 

 compressed near its base, meeting the lip at an acute angle, forming a very short canal. 

 Umbilicus slight, bounded externally by a revolving imbricated ridge. Epidermis horny, 

 elongated into bristles along the ribs. 



Color. Epidermis whitish yellow ; beneath this, brownish or yellowish white. 



Length, 0-75. Width, 0-45. 



This shell was first obtained from Melville island, and afterwards from the coast of Scot- 

 land, by Mr. Sowerby. It was subsequently obtained by Mr. Coulhouy, from the stomachs 

 of fishes off the coast of Massachusetts, and, in similar situations, will undoubtedly be found 

 here. The species described by Mr. Couthouy, he supposes to be distinct from the borealis, 

 by the greater breadth of the body-whorl of that species, its fewer number of ribs, and the 

 more conspicuous bristly fringe. Later conchological writers, together with Mr. Sowerby 

 himself, consider these two as indentical. 



Fauna — Part 6. 18 



