300 INVERTEBRATA OF MASSACHUSETTS. 



GENUS TRICHOTROPIS, BROD. and SOWERBY. 



Shell thin, ventricose, keeled, umbilicated ; aperture longer than 

 the spire, compressed into a partial canal in front ; epidermis 

 horny, rising into hairs at the angles of the shell ; operculum horny, 

 nucleus at one side. 



The genus TRICHOTROPIS was instituted by Mr. Sowerby to 

 include this and one other shell, which have unequivocal gen- 

 eric traits, but whose place in the series has not yet been deter- 

 mined. Lesson regards it as allied to JA'NTHINA ; and the spe- 

 cies which he knew might well lead him to such an opinion. Mr. 

 Sowerby at first compared it with TURBO, BU'CCINUM, and CAN- 

 CELLA RIA. But in his late work, the " Conchological Manual," 

 he places it among the PURPURIFER.E, where its aspect would 

 lead us to place it. It is very peculiar in having its axis fall con- 

 siderably to the left of the canal. 



TRICHO'TROPIS BOREA'LIS. 



Shell ovate-rhomboidal ; whorls four, the last very broad, and 

 encircled by four or jive, and the others by two, prominent, fringed 

 ribs, and crossed by minute and regular elevated lines ; umbilicated. 



FIGURE 207. 

 State Coll., No. 20. Soc. Cab., No. 2282. 



Trichotropis borealis, SOWERBY; Zool. Journ., iv. 373, pi. 9, f. 6, 7. 

 Trichotropis costellatus, COUTHOUY ; Bost. Journ. Nat. Hirf.,ii. 108, pi. 3,f. 2. 



Shell ovate-rhomboidal, turreted, spire pointed ; color ashy 

 or yellowish-white ; whorls four, separated by a deeply chan- 

 nelled suture ; the last whorl very large, and encircled by two 

 prominent, and two or three less conspicuous, rounded ribs or 

 keels, and several still smaller intervening and adjacent ones ; the 

 two large ribs only are continued upon the upper whorls, which 

 are thereby rendered angular ; very numerous, minute and regular 

 threads, traverse the length of the shell, not being interrupted by 

 the ribs ; the whole is covered by a yellowish horn-colored epi- 

 dermis, which rises like a bristly fringe along the keels, and along 



