Pecten. MOLLUSCA. BIVALVIA. 383 



pectenidj:. 



Gen. XCIV. PECTEN. Scallop.— SheU suborbicular ; 

 beaks approximate ; ligament internal, seated in a triangu- 

 lar cavity, a byssus issuing under the ear of the right valve ; 

 foot small, pedunculated ; mouth with branched tentacula. 



* Ears of the shell equal, or nearly so. 



371. P. maximus. — The left or upper valve flat, depressed 

 towards the beak, the ribs rounded and striated longitudinally. 



List. An. Ang. 184. Conch, t. clxiii. — Ostrea maxima, Linn. Syst. i. 

 1144.— P. max. Penn. Brit. Zool. iv. 99. t. lix. f. 61. Mont. Test. 

 Brit. 143. Turt. Bev. 207 — Gregarious on many parts of the coast. 

 Length about o inches ; under valve whitish, upper valve variegated with 

 brown; ribs 12 to 16, longitudinally grooved and transversely striated. 

 Dredged and used as food ; it is said by old fishermen, to be taken in great- 

 est quantity after a foil of snow. 



372. P. JacobcBus. — The upper valve flat, depressed towai'ds 

 the beak, the ribs rounded and destitute of longitudinal striae. 



P. magnus. List. Conch, t. clxv — Ostrea Jac. Linn. Syst. i. 1144 P, 



Jac Penn. Brit. Zool. iv. 100. t. Ix. f. 62. Mont. Test. Brit. 144, 



Turt. Biv. 208 — On the coast of England, rare. 



Length about 3 inches; lower valve white, upper valve rufous; ribs about 



16, in the upper valve rough, subquadrangular, with a few longitudinal 



grooves, the interstices nearly smooth ; the ribs in the lower valve rounded, 



and, together witli the grooves, transversely striated. 



373. P. opercularis. — The left valve convex ; ribs rounded, 

 nearly smooth. 



P. tenuis. List. An. Ang. 185. Conch, t. cxix — P. oper. Linn. Syst. i. 

 1147.— P. subrufus, Penn. Brit. Zool. iv. 100. t. Ix. f. 63._P' oper. 

 Mont. Test. Brit. 145. Turt. Biv. Brit. 209. and P. subrufus, p. 210. 

 —Common on oyster beds. 



Breadth from 2 to 3 inches ; coloured plain or variegated ; ribs about 18, 

 the whole shell obsoletely striated longitudinally, and finely striated trans- 

 versely, especially in the furrows. 



374. P. I'meatiis. — The left valve convex ; a red hne along 

 tlie rough ridge of each rib. 



(Da Costa, Brit. Conch. 147. t. x. f. 8.) Pult. Dorset. 36 — Ostrea lin. 

 Don. Brit. Shells, t. cxvi Southern coast of England. 



This shell is smaller than the preceding, the sides do not rise quite so 

 high towards the ears ; and the ribs are much finer. It seems to have been 

 first noticed by Dr Pultney. Dr Turton considers it as a variety of P. oper- 

 cularis. 



