PURPURIFERA. MOLLUSCA. TRICHOTROPIS. 301 



those lines which mark the stages of growth ; aperture ovate, broad 

 and rounded behind, narrowed and somewhat pointed in front ; 

 outer hp thin and sharp, festooned by the projecting ribs ; inner 

 lip arched and flattened, with a slight inward projection at the 

 lower third, rising before the umbilicus, which is also bounded ex- 

 ternally by a revolving ridge ; the two lips meet in front at an 

 acute angle, forming a short, slightly excavated canal, turning a lit- 

 tle to the right. Length y^ inch, breadth ■j\ inch, divergence 48°. 

 Found in considerable numbers, though rarely entire, in fishes 

 taken in Massachusetts Bay. 



Mr. Couthouy makes the principal points of difference between his 

 shell and the horedlis of Sowerby, to be, a greater number of keels 

 on the lower whorl, the less breadth of that whorl, and the shorter 

 fringe upon it. But these detailed portions are by no means constant. 

 I have sent specimens to Mr. Sowerby, who assures me, they are the 

 same as his horedlis received from Melville's Island, many years ago. 

 He also sent another imperfect shell, dredged at Oban, in Argyleshire, 

 by Mr. Jeffreys, and named by him T. acumindtus^ which I cannot 

 perceive to differ at all from our shell. This is probably its southern 

 limit. 



Pu'rpura lapi'llus. 



Shell ovate, pointed, solid, variegated in color, lohite, yellow, 

 chocolate, and often handed icitli white; surface with numerous 

 coarse, revolving ridges; aperture oval, outer lip thickened, and 

 toothed within. 



State Coll., No. 10 and 11. Soc. Cab., No. 1502. 



Buccinum lapillus, Lin.; Syst. JVat., 1202. Pennant ; Brit. ZooL, iv. 218, t. 72, 

 f 89. Martini; Conch., iii. 429, t. 121, f. 1111, 1112, and iv. 22, t. 122, 

 f. 1124, 1125, &c. Donovan ; Bril. Hhells, pi. 11. Wood ; Index, pi. 23, f. 02. 

 Montagu; Test. Brit., 239. 



Tritonium lapillus, Muller; ZooL Dan. Prodr., 244. 



Purpuro-Buccinurn, Da Costa; Brit. Conch., 125. 



Purpura lajullus, Lam.; j3/i. sans Vert., (1st. cd.) vi. Kiener; Iconog. (Pourpre,) 

 101, pi 29, 30, 31, f. 77 to 77*. Fleming ; Brit. Anim., 341 . 



Shell ovate, acutely pointed at both extremities, thick and 

 solid, varying in color, from white through yellow to a dark choc- 



