New Species of Shells. 165 



callosity which reaches nearly to the basal notch ; between the ba- 

 sal notch and this callosity is usually a brownish spot : length, 0.55 

 inch: breadth, 0.36 inch. 



Habitat, Caribbean Sea at Carthagena, S. A. 



Remarks. — This beautiful little Marginella was forwarded me 

 from Carthagena, by W. W. Whitney, Esq. It occurs abundantly 

 in company with M. interrupta Lam. and in its general aspect is 

 so much like that, as to be easily mistaken for it. But an attentive 

 examination of a large number of individuals of each species has 

 convinced me that they are entirely distinct. The M. interrupta is 

 less tumid, and the outer margin of its lip is wrinkled and most dis- 

 tinctly defined. The lip of the M. obesa is outwardly smooth, and 

 has so little distinctness of outline that when the shell is placed 

 with the back upwards, it might be taken for a Cyprasa. The M. 

 interrupta has often one or more reddish blotches upon the back of 

 the shell ; these I have never seen distinctly developed in the M. 

 obesa. On the other hand, the M. interrupta is destitute of the 

 black speckles which surround the spire of the M. obesa, and of 

 the black spots, which in the latter occur upon the outer margin of 

 the lip, and near the base of the columella. 



Tkiton Oregonense. Plate XI. fig. 2, a, b, — Cabinet of Dr. B. 



W. Build. Cabinet of Naval Lyceum, Brooklyn. 



Testa fusiformi, clongata, tcnui, albidi, epidermidc hirsuta fus- 

 ck induta. ; anfractibus rotundatis ; plicis longitudinalibus, costis et 

 sulcis transversis valde decussatis ; varicibus exilibus ; apertura 

 ovata, canaliculate, albiL 



Shell fusiform, elongate ; thin, whitish, covered with a rough, 

 hairy, brown epidermis; the whorls are rounded, with from 18 to 

 25 longitudinal folds which arc cancellated by transverse ribs and 

 furrows. There are four or five of these ribs on each of the up- 

 per whorls, and each rib is divided by a slight furrow, while the 

 intervening hollows are in like manner divided by a slight rid^e. 

 The last whorl has from 10 to 15 transverse ribs, and their bifid 

 character is not so conspicuous as upon the upper whorls. The va- 

 rices are about 12 in number, not prominent, and are crossed by 



