o4 PECTINID A. 
The shell also only shows specialty-variations, the principal 
one being sometimes, not always, a more oblique outline; m 
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. hians and P. subauriculatus, taken occasionally alive in 
the coralline districts. We have often seen it spm 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. ntveus, Macgillivray. 
P. niveus, Brit. Moll. 11. p. 276, pl. 50. f. 2; (animal) pl. S. f. 3. 
P. panicus, Chemnitz. 
P. danicus, Brit. Moll. 11. p. 288, pl. 52. f. 1, 2, 7, 8, 9, 10. 
P. Istanpicus, Miller. 
Vide Brit. Moll. ii. p. 303. 
P. tigrinus, Miller. 
P. tigrinus, Brit. Moll. 1. p. 285, pl. 51. f. 8-11. 
P. striatus, Brit. Moll. 1. p. 281, pl. 51. f. 1-4; (animal) pl. S. f. 2. 
P. obsoletus, Mont. et Turt. 
P. furtivus, nonnull. 
P. supauRicuLatus, Mont. et nobis. 
Lima subauriculatus, Brit. Moll. 11. p. 263, pl. 53. f. 4, 5. 
P. arans, Gmelin et nobis. 
Lima hians, Brit. Moll. u. p. 268, pl. 52. f. 3,4, 5; and (animal) 
pl. R. under the name of L. tenera. 
L. tenera, Turton. 
