NACELLA. 119 



tella Rochebrune and Mabille. These forms are like Nacella mytilina 

 in contour, but they are more solid and ribbed. 



Var. MAGELLANicA Gmeliu. PI. 44, figs. 9-17 ; pi. 43, figs. 1-6. 



Shell rounded-oval, high-conical, the apex nearly erect ; varying 

 from strongly radiately ribbed to smooth. Unicolored, radiately 

 streaked, or having oblique stripes. 



Interior generally very dark, the muscle-scar sometimes snowy- 

 white. Length 45, breadth 36, alt. 27 mill. 



P. magellanica Gmel., Syst. xiii, p. 3703. — Reeve, Conch. Icon., 

 f. 19. — Patinella viagellanica Dale, Amer. Journ. Conch, vi, p. 273, 

 t. 15, f. 24 (soft parts and dentition), — Patella atramentosa Rve., 

 Conch. Icon., f. 41. — P. venosa Rv., f. 18. — P. chilcensis Rv., f. 98. — 

 P. meridionalis Rochebrune & Mabille, Bull. Soc. Phil. Paris 

 7th Ser., ix, p. 109, 1885 ; Mission Scientifique du Cap Horn, vi, 

 p. 94, t. v, f. 4.— P. metallica R. & M., I. c, p. 91, t. 5, f. 5.— P. 

 pupillata R. & M., /. c, p. 92, t. 5, f. 6.— P. tinda R. & M., I. c, p. 

 93, t. 5, f. 7. 



Rounder than typical cBnea, and having a more central, erect and 

 elevated apex. 



Here belong a number of forms described by Reeve years ago, 

 and by Rochebrune and Mabille recently. The paper by the last 

 authors, on the mollusks of Cape Horn, is an admirable specimen of 

 how systematic zoological work should not be done. The ignorance 

 displayed is only excelled by the lack of judgment. We should, 

 however, give MM. Rochebrune and Mabille the benefit of the 

 doubt as to whether their species and groups were intended seriously 

 or as a jest. 



• This variety is well represented by the figures 9-11 of pi. 44, 

 drawn from specimens collected at Santa Cruz River, Patagonia. 

 The ribs are strong and carinated in some specimens, almost com- 

 pletely obsolete in others, this comparative smoothness not being the 

 result of erosion. The central area of the interior is sometimes 

 partly of a snow-white color (pi. 44, fig. 12) ; sometimes the muscle- 

 scar is white (pi. 44, fig. 16.) 



P. meridionalis R. & M. (pi. 43, figs. 1, 2), P. pupillata R. & M, 

 (pi. 43, figs. 3, 4), P. tincta R. & M. (pi. 43, figs. 5, 6) and P. 

 metallica R. & M. (pi. 44, figs. 17) are ordinary forms o^ magellanica. 



The form called atramentosa by Reeve (pi. 44, figs. 13, 14,) has 

 the ribs wide and subobsolete ; whitish with broad blackish rays. 



