FISSURELLA. 145 



foration oblong, nearly twice as long as wide, about one-ninth the 

 length of the shell. 



It is a little narrower in front, more conical than jP. maxima but 

 less elevated than F. picta. Whitish, becoming dark ashen or 

 bluish at the edges, painted with numerous (about 13) reddish rays. 

 Inside white, with a bluish-black border. Muscle-impression wide, 

 smooth, not defined. Length 56, breadth 37, alt. 15 mill. 



Straits of Magellan. 



F. Darwinii REEVE Conch. Icon. f. 7, 1849. 



This form is closely allied to F. maxima, but is higher, the mus- 

 cle-scar broader and nearer to the margins, and the border is deep 

 blackish-blue in color. Figs. 15-17 of plate 46 are drawn from 

 the only specimen I have seen. It differs from F. picta in being 

 less elevated and lacking strong concentric w r rinkles, but may never- 

 theless prove to be an immature or arrested stage of that species. 



F. MAXIMA Sowerby. PI. 30, figs. 8, 9 ; pi. 33, figs. 46, 47. 



Shell elliptical, a little narrower anteriorly, rather depressed, the 

 apex subcentral ; sculptured with rather weak radiating riblets, 

 which are somewhat uneven or tuberculate. Perforation oval, 

 about one-tenth the length of shell ; interior dark-edged. Length 

 1 times the breadth, more or less. 



The outline is egg-shaped, more broadly rounded posteriorly. 

 The cone is low, slopes feebly convex, often subconcave in places. 

 It is solid and strong, of a whitish fawn-color, with broad rays of 

 purplish-red, about 13 in number. The surface has rather weak, 

 unequal radiating riblets, somewhat granose or roughened by rude 

 growth-lines. The perforation is subcentral, about H times as long 

 as broad, elliptical in form. Inside white ; central callus elliptical, 

 not thickened ; margin not crenulated, pallidly edged with the 

 colors of the outside. 



Length 82, width 56, alt. 13 mill. 



Length 100, width 68, alt. 21 mill. 



Valparaiso, Chili, to Peru. 



F. maxima SOWB. P. Z. S. 1834, p. 123 ; Conchol. Illust., f. 18. 

 SOWB. Thes. Conch, iii, p. 187, t. 236, f. 8, 9. D'ORBIGNY, Voy. 

 Amer. Merid. -v, p. 475, t. 64, f. 4-7. REEVE, Conch. Icon., f. 22. 

 WATSON, Challenger Gastrop., p. 33. PHILIPPI, Abbild. ii, t. 

 1, f. 1. 



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