PATELLA-SCUTELLASTRA. 95 



Animal similar to Patella, except that a small rhachidian tooth is 

 frequently developed. 



Distribution, S. Africa to Central Pacific. 



I have separated this group from Patella s. s. mainly on account 

 of the different texture of the shell. Although this distinction has 

 not heretofore been noticed, 1 am confident that it is constant and 

 of sufficient systematic value to warrant the course here taken. 



(1) GROUP OF P. BARBARA. 



Erect, oval shells, with numerous ribs or riblets. 

 P. ARGENVILLEI Krauss. PI. 22, figs. 15, 16 ; pi. 58, fig. 44. 



Shell large, solid, elevated-conical, ovate, apex in front of the 

 middle, slopes nearly straight. Surface closely sculptured with 

 numerous (80-100) crowded, obtuse radiating riblets, obscurely 

 alternating in size, and roughened by the low, scaly growth-lines. 

 Color blackish, having concentric lighter zones. 



Interior white, stained at the muscle-scar with brown or yellowish- 

 brown, the edges of the central area well-defined, laciniate, stained : 

 border brown, closely crenulated by small teeth arranged in pairs. 



Length 81, breadth 62, alt. 43 mill. 



Table Bay, South Africa. 



P. argenvillei KRAUSS, Die Siidafric Moll., p. 49. REEVE, Conch 

 Icon., f. 20. ? Lepas ecaille ARGENVILLE, La Conchyl., p. 504, t 

 3, f. G. 



P. NEGLECT A Gray. PI. 20, figs. 41, 42 ; pi. 58 , figs. 40, 41. 



Shell large, solid, elevated-conical, elliptical or ovate ; apex at 

 about the front third ; slopes nearly straight. Surface sculptured 

 with coarse, irregularly subnodose, unequal radiating riblets. Ribs 

 whitish, interstices blackish brown. 



Interior white, tinged with flesh-color, having some yellowish- 

 brown clouds or stains in the central area ; muscle-scar distinct, 

 light-buff or flesh-tinted. Edge of the shell crenated, conspicuously 

 marked with black-brown blotches, mostly in pairs. 



Length 95, breadth, 68, alt. 40 mill. 



Length 106, breadth 80, alt. 41 mill. 



King George's Sound, Mistaken Island, and Swan River, Aus- 

 tralia. 



f P. rustica LINN., Mus. Lud. Ulricse p. 694, (not of Linn. Syst. 

 Nat. x, = P. lusitanica Gm., q. v.~) P. rustica L., MENKE, Moll. 



