364 PURPURID^. 



Nassa trivittata. 



Fig. 211. 



Shell ovate-conic, turreted, greenish-white, surfiice wrought into a network by 

 elevated, decussating lines ; sometimes with three dark bands on the lower whorl; 

 raised lines within the lip. 



Ndssa tricitiafa, Say, Journ. Acad. Nat. Sc. ii. 2.31. — Smrrsox, Check Lists, 5. 

 Bucciiiuin tiivittatum, Adams, Bost. Jouni. Nat. IJist. ii. 2C5. — Gould, Inv. 1st cd. 309, 

 fig. 211. 



Shell ovate-conic, turreted, apex acute, greenish or yellowish- 

 white, cross-barred, so as to appear granulated, by means of promi- 

 nent, equidistant, longitudinal lines, and ten, equally reg- 

 Fig. 632. x\\?iV, revolving impressed lines on the larger whorl, and 

 a somewhat more conspicuous groove near the summit of 

 each volution ; whorls seven, flattened above, so as to pre- 

 sent a conspicuous shoulder at the suture ; in the best speci- 

 mens there is a dark band at the top, on the middle, and 

 -, , . .„ , at the front of the body whorl, each occupying two series 



A", trivittata. J ' i j » 



of granules ; the lower line of granules on each whorl is 

 also colored, aperture oval, terminating behind in a canal formed by 

 a dilatation of the right lip, and a fold on the left, and before in a 

 short, ascending beak which is divided from the body of the shell 

 by a deep groove ; outer lip sharp, and scalloped by the revolving 

 lines; pillar regularly arched, with a distinct revolving ridge bor- 

 dering the canal, and covered, to a consideral)le extent, with green- 

 ish enamel ; throat white, or with brown bands corresponding to 

 those on the outside ; a few elevated lines within, not reaching the 

 margin ; operculum horny, of an irregular, three-sided shape, one 

 half its edge sharply serrated. Length, seven tenths of an inch ; 

 breadth, three tenths of an inch ; divergence, forty-five degrees. 



Found in a worn state on most of our sea-beaches, and occasion- 

 ally alive at Chelsea. Dr. William Prescott of Lynn found it alive, 

 in abundance, at low-water mark, on Phillips's Beach ; Professor 

 C. B. Adams found it at New Bedford, and says it is abundant at 

 Nantucket, on the iiyier side of Brant Point, and also on the south 

 shore, less abundant but larger. Halifax ( Willis') ; Eastport (Coop- 

 er) ; Gaspe (Bell) ; Gull Island (Smith) ; Vineyard Sound (De- 

 sor) ', Gcovgin (Co uper). 



No other shell inhabiting our coast bears any near resemblance 

 to this. Its sculpture is like that of B. margnnulatum from the In- 

 dian Seas, and its whole appearance is very much like that cf Kicu- 



