PECTEN. 



Plate IX. 



Species 37. (Fig- a, b, c, Mus. Cuming.) 



Pecten gibbus. Pect. testa subg'Ma, aqulvalvi, aq^iila- 

 terali, costis mediocribus octodecim ad viffiiili radlatd, 

 costis interstitiisqiie minute creberrime serrato-Uratis, 

 rosacea vel alba, cinereo-nigricante marmoratd, inter- 

 dum intense purjmrascente-sanynined, immacidatd, valvd 

 dextrd plerumque pallidiore ; auriculis subceqiudibm. 



The gibbous Pecten. Shell rather gibbous, equivalve, 

 equilateral, rayed with eighteen to twenty middling 

 ribs, ribs and interstices minutely very closely ser- 

 rately ridged, pink or white, marbled with ash-black, 

 sometimes deep purplish blood-colour, unspotted, 

 right valve generally paler ; ears nearly equal. 



Oatrea gibba, Linnseus, Syst. Nat. (12th edit.) p. 1147. 

 Pecten gibbus, Lamarck. 

 Pecten rubicundus, Chemnitz. 

 Pecten Soicerbyi, Guilding. 

 Ostreajiabellum, GmeUn. 



Hob. Senegal, West Africa. 



Mostly of a marbled variegated painting, although the 

 marbling is sometimes wanting. 



Species 38. (Mus. Cuming.) 



Pecten masimus. Pect. testa suboblongo-rotundatd, vix 

 aquilaterali, inaqtttvalvi, valvis radiatim irregulariter 

 lineari-liratis, costis duodecim ad tredecim convexis ; 

 valvd sinistra plamdatd, medio leviter elevatd, prope 

 ■icmbonem depresso-concavd, in valvd dextrd subimmersd, 

 rufo-fuscd, castaneo sparsim macidatd ; valvd dextrd 

 convexd, siibgibbd, albidd; aiiricidis ceqiialibus. 

 The largest Pecten. Shell somewhat oblong-rounded, 

 nearly equilateral, inequivalve, valves radiately irre- 

 gularly linearly ridged, with twelve to thirteen convex 

 ribs ; left valve flattened, slightly raised in the middle, 

 depressly concave near the umbo, a little immersed 

 in the right valve, red-brown, sparingly spotted with 

 chestnut; right valve convex, rather gibbous, whitish; 

 ears equal. 

 Ostrea maxima, Linnaeus, Syst. Nat. (12th edit.) p. 1144. 

 Pecten maximns, Lamarck. 

 Pecten vulgaris. Da Costa. 

 Ilab. British and Mediterranean Seas. 



This well-known scallop is chiefly distinguished from 

 its nearest ally, the P. JacobcBus, by the broad gentle con- 

 vexity of the right ribs. 



December, 1852. 



