PATELLA-SCUTELLASTRA. 97 



Mus. Oes. Vindob., t. 18, f. 1. REEVE, Conch. Icon., f. 16. P. 

 barbata LAM., An. s. Vert, vi, p. 326. DELESSERT, Rec. de Coq., t. 

 21, f. 1. P. spinifera LAM., An. s. Vert, vi, p. 326. DELESSERT, 

 Rec., t. 21, f. 2.? ? P. cypria GMEL., Syst. xiii, p. 3698. 



In all the variety of forms and names in which this species- 

 masquerades, it may be known by the acute, high, compressed ridges, 

 which bear vaulted or sometimes solid spines, usually touched with 

 brown at their tips. The ribs are unusually variable in number, 24 

 to 30 being developed on moderate sized individuals, not counting a 

 few small interstitial riblets. The spines are rarely as numerous as 

 Reeve's figures show. These are reproduced on pi. 15, figs. 1, 2. 



An elevated, conical form is figured on pi. 59, fig. 55. 



A form which may be known as var. OVALIS is figured on pi. 60> 

 figs. 56, 57, 58. It is ovate and has about 41 ribs. Interior pure 

 white. 



Length 95, breadth 70, alt. 31 mill. 



(2) GROUP OF P. STELL^EFORMIS. 



Shell having coarse, unequal ribs or riblets. 



P. PICA Reeve. PI. 22, figs. 9, 10, 13, 14 ; pi. 59, figs. 47, 48, 49 ; 



pi. 26, figs. 28, 29. 



Shell solid, depressed, apex a little anterior, ovate, broad behind, 

 more or less narrowed in front ; having numerous (about 21) rude 

 angular radiating ribs, and more or less obviously radiately striate. 

 Whitish or ashen, irregularly blotched with black. 



Interior white, the central area sometimes stained with yellowish 

 or brown. Edge crenated, having a narrow border which is usually 

 whitish-buff dotted and blotched with black, but sometimes lacks all 

 dark markings. 



Length 43, breadth 31, alt. 10 mill. 



Length 47, breadth 37, alt. 10 mill. 



Mauritius and Reunion* 



P. pica REEVE, Conch. Icon., f. 45, 1854; also f. 68. P^ 

 chitonoides REEVE, f. 52. DESK., Moll. Reunion, p. 43. P. moreli 

 DH., Moll. Reunion, p. 43, t. 6, f. 13. P. levata DH., I. c., p. 44, t. 

 6,f. 14. / P. dentata DUFO, Ann. Sci. Nat. 1840, p. 204. 



The outline is somewhat spoon shaped, approaching that of P. 

 cochlear. The ribs are usually subequal, and about 21 in number, 

 but sometimes they are very irregular, as in the figures on pi. 59. 

 7 



