FAMILY 4. PECTINACEA. 159 



was invariably very small. One species, the Pecten Pusio (PI. CIV. f. 6.), 

 is remarkable on account of its shell being generally found attached to 

 some marine body by the lower valve, thus forming an intermediate 

 transition to the PlicatulcE and Spondyli. Defrance proposes to esta- 

 blish a new genus for it, Hinnites, and we certainly think that this 

 arrangement may be adopted with advantage. 



The shell of Pecten may be described as being roundish, rarely attached, 

 regular, inequivalve, and nearly equilateral ; the valves are pectiniform, 

 unequally auriculated, disposed in ribs or furrows radiating from the 

 umbones to the margins, and sometimes, but very rarely, a little gaping. 

 The hinge is edentulate, linear, and furnished with an internal ligament, 

 which is tripartite ; besides the thick, solid, triangular portion inserted in 

 a small pit in the centre, there is a thin portion running parallel with the 

 hinge margin on each side of it. The muscular impression is large and 

 sublateral. 



Examples. 



PI. CX1II. Fig. 1. 



Pecten turgidus, Lamarck, Anim. sans vert., vol. vii. p. 135. Chem- 

 nitz, Conch., vol. vii. pi. 65. f. 621. a, b. 

 Ostrea turgida, Gmelin. 



PL CXIII. Fig. 2. 



Pecten fuscus, Sowerby, Genera of Shells, No. 31. 



PL CXIII. Fig. 3. 



Pecten pleuronectes, Lamarck, Anim. sans vert., new edit., vol. vii. 



p. 132. Enc. Meth., pi. 208. f. 3. De Blainville, Manuel de Mala- 



cologie, pi. 60. f. 5. 

 Ostrea pleuronectes, Linnaeus. 



PL CXIII. Fig. 4. 



Pecten pallium, Lamarck, Anim. sans vert., vol. vii. p. 140. Enc. Meth., 



pi. 210. f. 1. Chemnitz, Conch., vol. vii. pi. 64. f. 607 and 608. 

 Ostrea pallium, Linnaeus. 



