FISSURELLA. 147 



very easy to tell from the similar Chilian forms. The riblets as well 

 as the lines of growth are sometimes stronger, sometimes weaker, so 

 that the shell is sometimes very rough, sometimes smooth ; but never 

 is it so smooth as F. grandis [F. nigra Less.] or F. violacea, and 

 young individuals are remarkably latticed. These have also, 

 frequently, light rays, which vanish further on. Size, contour and 

 altitude are similar to F. oriens Sow., the hole smaller, placed more 

 posteriorly, and surrounded by a narrow horizontal white margin. 

 (Phil.} Length 20, breadth 12, alt, 5 lines. 



Chili. 



F. nigra PHIL. Arch. f. Naturgesch. 1845, i, p. 60 ; Abbild. ii, t. 

 2, f. 2 (not F. nigra Lesson). F. Philippiana KEEVE Conchol. 

 Icon., errata to Fissurella and f. 37. SOWB. Thes. Conch, iii, p. 186, 

 f. 30. F. atrata REEVE, Conch. Icon., t. 11, f. 73. 



The F. atrata of Reeve (pi. 34, fig. 59) is evidently synonymous. 



F. LATA Sowerby. PL 31, figs. 18, 19. 



Shell rounded-oval, elevated, conical, the summit a little in front 

 of the center, radiately sculptured with unequal, somewhat granose 

 riblets. Perforation oblong, a little less than half as wide as long, 

 and about one-ninth the length of shell. 



The shell is quite conical, short-oval, the sloping sides a little 

 convex or nearly straight. It is a trifle wider behind the middle ; 

 solid, grayish with numerous rays of purplish-red. The surface has 

 numerous little-raised and rather ill-defined radiating riblets, of 

 which one in the middle of each light ray is generally stronger ; 

 they are all roughened by low, irregular but rather acute granose 

 swellings. Inside white, rather smooth ; margin alternating gray 

 and reddish, especially in immature examples. Sides of the perfora- 

 tion nearly perpendicular, and in some shells the surface just around 

 it is rather speckled than rayed. 



Length 83, breadth 66, alt. 28 mill. 



Length 63, breadth 50, alt. 25 mill. 



Chili. 



F. lata SOWERBY P. Z. S. 1834, p. 124 ; Conch. 111. f. 63. REEVE, 

 Conch. Icon. f. 5. 



A shorter, more elevated species than maxima ; more allied to the 

 F. costata of Lesson, but that shell is flatter and the perforation is 

 smaller. 



