PATELLLA-SCUTELLASTRA. 



99 



Interior white, frequently slightly stained in places with yellow- 

 ish ; central area white or stained with fleshy-brown, the muscle- 

 scar sometimes outlined with reddish-brown. Margin very irregu- 

 larly toothed. Length 45, breadth 35, alt. 14 mill. 



Japan to Port Jackson, S. Australia ; eastward to Viti, Cook's and 

 Society Archipelagos. 



P. stellceformis Reeve, Conch. Syst. ii, p. 15, t. 136, f. 3, 1842.— 

 DuNKER, Ind. Moll. Mar. Jap., p. 156. — P. pentagona Reeve, 

 Conch. Icon., f. 48, 1854 — Lischke, Jap. Meeresconchyl. i, p. 114 

 (not P. pentagona Born).— Angas, P. Z. S. 1867, p. 221.— Dall, 

 Amer. Journ. Conch, vi, p. 272, t. 15, f. 22 (dentition). — P. paumo- 

 tensis Gld., Proc. Bost. Soc. N. H. ii, p. 150, 1846 ; U. S. Expl. 

 Exped. Moll. & Sh., p. 339, f. 440.— P. cretacea Reeve, Conch. Icon., 

 f. 53.— P. tramoserica Ad., Ann. Mag. N. H. 1868, p. 369. 



This excessively variable species is allied to P. pica, differing 

 mainly in not being narrowed anteriorly as a general rule. The 

 main distinction, however, is geographic, the present form being 

 Pacific, in distribution, whilst pica (and its immediate allies or 

 varieties) is from the western part of the Indian Ocean. I doubt the 

 occurrence of true stellcBformis in the last mentioned area. 



It is impossible to say what P. pentagona Born (Mus. Test. Cses. 

 Vindob., p. 421, t. 18, f. 4, 5) is intended for. It is certainly not 

 this species. Von Martens surmises that it may not belong to the 

 Patellidce. The figures somewhat resemble a large Siphonaria. 



The typical form of stellceformis has 8 to 10 larger ribs. 



Among the large number of minor modifications, typically quite 

 diverse but intergrading by easy stages with the types, the following 

 may be noticed : 



Var. PAUMOTENsis Gld. (pi. 47, figs. 4, 5). Outline much more 

 regularly oval ; riblets very numerous and subequal. P. cretacea 

 Rv. is a synonym. 



Another slightly differing form is figures on pi. 61, figs. 62, 63, 64. 

 It is large, oval, coarsely ribbed, with fine secondary radiating striae. 

 The interior is marked with brown. 



The specimen figured on pi. 61, fig. 65 has a great similarity to 

 Reeve's P. stellaris, and I am inclined to believe it is the same. It 

 is very distinctly octoradiate, the ribs wide ; both ribs and intervals 

 finely striated radially. See p. 51 of this volume for remarks on 

 Reeve's stellaris, and pi. 36, figs. 65, 6Q, copies of the original 

 figures. 



