54 PECTINID^E. 



The shell also only shows specialty-variations, the principal 

 one being sometimes, not always, a more oblique outline ; in 

 it we observe the same character of the ligamental and carti- 

 laginous areas, a similar disposition of the longitudinal ribs, 

 and the greater or less emargination of the valve under the 

 posterior auricle, for the byssus, by which they are all fixed 

 at some part of their existence, usually when young, and 

 becoming often free when adult. With these views, I am 

 compelled to consider Lima as a superfluous genus, and 

 merge it in Pecten ; I cannot call the same animal both Lima 

 and Pecten. The conchologists, perhaps some malacologists, 

 will condemn these innovations ; but the knowledge of the 

 animal configuration gives me the moral courage to perform the 

 necessary amputations, for the benefit and safety of the system. 



This animal is rare at Exmouth at present, but was more 

 plentiful some years ago ; it is, with its only two congeners, 

 the P. Mans and P. subauriculatus, taken occasionally alive in 

 the coralline districts. We have often seen it spin a byssus 

 and fix itself. The animals of this section often collect and 

 agglutinate in a mass minute nullipores, thus forming a nidus 

 and harbour of refuge. 



The following Pectens have not been observed : 



P. NIVEUS, Macgillivray. 



P. niveus, Brit. Moll. ii. p. 276, pi. 50. f. 2 ; (animal) pi. S. f. 3. 

 P. DANICUS, Chemnitz. 



P. danicus, Brit. Moll. ii. p. 288, pi. 52. f. 1, 2, 7, 8, 9, 10. 



P. ISLANDICUS, Miiller. 



Vide Brit. Moll. ii. p. 303. 

 P. TIGRINUS, Miiller. 



P. tigrinus, Brit. Moll. ii. p. 285, pi. 51. f. 8-11. 



P. striatus, Brit. Moll. ii. p. 281, pi. 51. f. 1-4 ; (animal) pi. S. f. 2. 



P. obsoletus, Mont, et Turt. 



P.furtivus, nonnull. 



P. suBAUiucuLATus, Mont, et nobis. 



Lima subauriculatus, Brit. Moll. ii. p. 263, pi. 53. f. 4, 5. 

 P. HIANS, Gmelin et nobis. 



Lima hians, Brit. Moll. ii. p. 268, pi. 52. f. 3, 4, 5; and (animal) 

 pi. R. under the nainr of L. Icnera. 



L. lencni, Turton. 



