PATELLA. 87 



of brown showing through it, ornamented with concentric, undu- 

 lating lines of obscure white. Interior greenish-white, with bright 

 iridescent reflections ; a slight spatulaform deposit at the fundus, 

 bluish at the edges and forepart, passing into greenish towards the 

 middle and posterior portions. ( Old.~) 

 Length !*, breadth 1 inch. 



Funchal, Madeira Is. 



P. citrullus OLD. Proc. Bost. Soc. N. H., ii, p. 149, July, 1886 ; 

 U. S. Expl. Exped. Moll. & Sh. 335, f. 448. 



This shell resembles somewhat the skin of a cucumber externally. 

 The radiating striae occupy the upper half of the shell, and the 

 lower half is somewhat imbricated by the stage of growth. It is 

 somewhat like P. Candei D'Orb. ( Old.) 



I have not seen this species. It should be compared with P. 

 cosrulea var. crenata, and with P. candei. 



P. LUSITANICA Gmelin. PI. 11, figs. 15, 16, 17, 18, 19. 



Shell solid, conical, rounded-oval, the apex elevated and slightly 

 in front of the middle; front slope straight, posterior slope slightly 

 convex. Surface dull, lusterless ; having close unequal, granose radi- 

 ating riblets. Ashen-white, with blackish rays wider than the 

 white ones, the granules on the ribs black. 



Interior rayed with brown or purplish-black on a lighter ground, 

 the central area white, brown or blue-black, often surrounded by 

 a yellow stain. . Length 35, breadth 29, alt. 16 mill. 



Mediterranean and A'driatic Seas ; Atlantic coast of Portugal and 

 S. W. France ( Gironde) ; Madeira. 



P. rustica LINN., Syst. Nat. x, p. 783, teste HANLEY, Shells of L., 

 p. 427 (Not P. rustica LINN., Mus. Ulricse, nor of REEVE, Conch. 

 Icon., nor of MIONKIO, Moll. Nov. Holl. Spec.). P. lusitanica GMEL., 

 Syst. p. 3715. PHIL., Enum. Moll. Sicil. i, p. 110. HIDALGO, 

 Mol. Mar. Esp. 51, f. 3, 8. BUQ. DAUTZ. & DOLLF., Moll. Mar. 

 Rouss. i, p. 469, t. 57. P. granularis v. SALIS et al, not Linn. 

 P. nigropunctata REEVE, Conch. Icon. f. 57. P. piperata GLD., U. 

 S. Exped. Moll. p. 338, atlas f. 449. 



The conical form and dark or black granules upon the radiating 

 riblets readily distinguish this species. 



