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 Trichutropis 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 PuRPURiFERiE, 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. 



SJiell ovate-rhomboidal ; ivhorls four, the last very broad, and 

 encircled by four or five, 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 boiealis, Sowerby ; Zool. Journ., iv. 373, pi. 9, f. 6, 7. 

 Trichotropis costellatus, Couthouy ; Bost. Journ. JVat. Hist. ,ii. 108, pi. 3, f. 2. 



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

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

 nel)"'' 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 ihe keels, and along 



