OF CONCHOLOGY. 263 



Type ScuRRiA scurra, Lesson sp. 



Patella scurra, Lesson, Voy. Coq. Zool. p. 421, No. 189, 1830. 

 Acmcea scurra, D'Orb., Voy. Amer. Merid. v, p. 478, pL 



Ixiv, fig. 11 — 14. 

 Scurria scurra, Gray, P. Z. S. 1847, p. 158. Guide Moll. p. 



171. Chenu, Man. de Conchyl. i, p. 375, fig. 2812. 



H. and A. Ad., Gen. Rec. Moll, i, p. 460, iii, pi. lii, 



fig. 4, a, b. 

 Lottia pallida, Sby., Moll. Beechey's Voy. p. 147, pi. xxxix, 



f. 1, 1839. Not Fatella pallida, Gould. 

 Lottia €07iica, Gld., Moll. U. S. Expl. Exp. p. 346, (pars). 

 Not Acma^a mitra, Esch., (Zool. Atlas, ed. Rathke v, p. 18,) 



as aver Gray and Adams. 

 Acmcea mitra, Alcock, (MSS.), in Am. J. Conch, ii, p. 345 



not Eschscboltz. 

 Lottia scurra ? Gld., Expl. Exp. Moll. p. 356. 



Soft parts yellowish white for the most part ; foot large, sub- 

 oval, smooth ; mantle edge thickened, smooth, finely fringed with 

 short marginal cirri ; head very large, of a rosy tint ; muzzle 

 short, frilled ; tentacles large and slender, faintly roseate, with 

 very minute black eyes at their lateral and posterior bases. 

 Branchial lamellae resembling those of Patella, but rather more 

 distant, erectile ; gill very stout, thick, with a rather broad 

 border formed by an impressed line on each side ; lamellae 

 prominent, apex pointed. 



Shell buff, outer layer of a waxen translucency, inner layer 

 porcellanous white, with narrow margin resembling the external 

 layer. Form conical ; apex usually minute, sharply pointed, 

 anteriorly directed, (not blunt and erect, as in Acmcea mitra) ; 

 anterior and posterior slopes convex (seldom or never concave, 

 as is frequent in A. mitra) ; aperture roundly oval, slightly 

 narrower in front, external surface covered with fine, regular, 

 even striae, like threads radiating from the apex (very diiferent 

 from the rough, irregular, bifurcating riblets of the varieties of 

 A. mitra) ; internal surface of a peculiarly glossy white, scored 

 with more or less strongly marked radiations from the apex ; 

 margin obsoletely crenulate inside ; apex often white, but not 

 uncommonly marked with brown streaks on a white ground, 

 radiating from a dark brown nucleus and divaricating ; apex of 

 this young fry strongly recurved, nearly marginal, without any 

 trace of a spiral nucleus. The concentric lines of growth are 

 more or less strongly marked but usually rounded and obsolete. 



Habitat from 12° to 41° s. lat. on the west coast of South 

 America. It lives on the roots and stalks of fuci [Macro cystis), 



