HELCIONISCUS. 125 



front segment often darker, the edges more or less leaden. Edge 

 of shell narrowly bordered with slate-color. 



Length 58, breadth 52, alt. 19 mill., (fig. 65.) 



Length 48, breadth 40, alt. 24 mill., (fig. 66.) 



Island of Juan Fernandez. 



P. ardosicea H. & J., Ann. des Sci. Nat. (2), xvi, p. 190, (1841). 

 P. clathratula REEVE, Conch. Icon., f. 30, (1854.) 



This is a very distinct form, allied to P. tahitensis Pse. but not 

 granulose (although there are concentric striae), and not variegated. 

 There are often very fine concentric wrinkles inside ; and the interior 

 sometimes has an opaque white or lemon-tinted peripheral zone, or 

 rarely the entire surface between the reddish spatula and the narrow 

 border is silvery-yellow. 



Half-grown specimens greatly resemble Hutton's P. olivacea 

 except that that species has the apex slightly more anterior, the 

 spatula broader in front and not reddish, and the border narrower 

 and blacker. 



This is one of the few species of Hombron and Jacquinot's paper 

 which is portrayed by them with unmistakable accuracy. The 

 specimens orginally described and those of Reeve, as well as the 

 originals of my figures 64, 65, 66, were from Juan Fernandez. 



H. NIGRISQUAMATUS Reeve. PI. 19, figs. 35, 36 ; pi. 48, figs. 13, 14, 



15. 



Shell solid, oval, erectly, straightly conical, the altitude about half 

 the breadth ; apex erect, acute, a little in front of the center. Sculp- 

 tured with strong, narrow, closely nodule-scaled ribs, obscurely or 

 obviously alternating in size, and about 46-51 in number. Color 

 yellowish, often blackish-gray above and orange around the circum- 

 ference, having here and there scattered black scales or nodules. 



Interior silvery, more or less orange-tinted and decidedly iri- 

 descent, the central area small, dark chestnut colored. In young or 

 half-grown shells the interior shows black spots corresponding to the 

 black nodules of the outer surface, but in adults they are obscured by 

 the enlarging central callus. Edge having a narrow distinct fleshy- 

 orange border. 



Length 63, breadth 52, alt. 28 mill. 



Length 83, breadth 71 mill. 



Concepcion, Chili (Dr. Ruschenberger) ; Australia (Reeve.) 



