104 PATELLA-SCrTKLLASTRA. 



P. VIDUA Reeve. PI. (53, figs. 78, 79. 



Shell ovate, moderately convex ; strongly, sharply ribbed, ribs 

 alternately smaller, minutely scaled, scales distant, the alternate rib 

 sometimes nearly obsolete ; rusty-black, eroded at the apex. Inte- 

 rior whitish, with a broad rusty-black band at the edge; nucleus 

 pale rust. (Rve.) 



Island of Camiguing, Philippines. 



P. vidua RVE., Conch. Icon. f. 22, Oct. 1854. 



A moderately convex shell, rayed with sharp ribs, alternately 

 larger and smaller, each rib being roughened with minute, some- 

 what distant scales. The chief characteristic of this species lies in 

 its broad deep rust-black marginal border. (Rve.) 



(4.) GROUP OF P. COCHLEAR. 



Shell spoon-shaped, produced and narrowed in front ; ribs numer- 

 ous, subequal. 



P. COCHLEAR Born. PL 27, figs. 34, 35. 



Shell spoon-shaped, depressed, solid ; apex subcentral. Surface 

 having numerous close radiating riblets, grayish or blackish, usu- 

 ally encrusted or eroded. 



Interior white or purplish-blue, the muscle-scar black. 



Length 60, breadth 45, alt. 15 mill. 



Cape Good Hope. 



P. cochlear BORN, Mus. Cses. Vindob. p. 420, t. 18, f. 3. REEVE, 

 Conch. Syst. ii, t. 136, f. 5; Conch. Icon. f. 24. KRAUSS, Die 

 Siidafric. Moll. p. 48. 



The curiously narrowed anterior end gives a spoonlike appear- 

 ance to this shell. Some specimens are almost perfectly flat, and 

 have a red central callus. 



It has been made the type of a subgenus by the Adams brothers, 

 but a number of other species approach it m contour, and form con- 

 necting links with the oval limpets. 



(5) GROUP OF P. LONGICOSTA. 



Shell large, having some (usually 7-11) of the ribs decidedly 

 larger, rendering the outline more or less polygonal. Distribution, 

 S. Africa. 



