PECTEN. 53 



Some malacologists think that the P. niveus of the Caledonian 

 shores is a variety of P. varius we believe from the shell it is 

 distinct, but the animal must determine ; it has not occurred 

 on our southern coasts. The P. tigrinus, the P. obsoletus of 

 authors, is frequently taken alive in Exmouth Bay ; but it is 

 a variety, though ribbed at the margin, of a smoother mould 

 than the Scotch specimens, which from their variableness 

 have been manufactured into three or four species, as before 

 observed. The P. danicus is Scotch, and the P. islandicus 

 probably spurious. 



** Shell thin and of vitreous texture, varying from a perfectly symmetrical 



to an oblique outline. 



P. FRAGILIS, Montagu et nobis. 



Lima Loscombii, Sowerby. 



, Brit. Moll. ii. p. 265, pi. 53. f. 1, 2, 3. 



We have yet to learn why this animal has received the spe- 

 cific title of " Loscombii :" surely the far prior and more ap- 

 propriate appellation of the excellent Montagu and other 

 authors ought to be adopted. We do not understand the 

 changing old accredited names for complimentary ones. 



This animal presents no essential difference from that of 

 Pecten ; it is even difficult to appreciate the specialties, which 

 only consist in the greater length of the three rows of the 

 tentacular filaments of the mantle, which are long, close-set 

 and numerous, of the various hues of pink and white. We 

 have seen twenty of these animals alive; they exhibit the 

 same character of the liver, branchiae, palpi, minute foot, pink 

 ovaria, of most of the Pectines ; the ocelli in the minuter spe- 

 cies are obsolete, but the rudiments of them are perceptible ; 

 the same kind of locomotion in the so-called Lima, as in 

 Pecten, I have frequently observed when placed in sea-water, 

 in a shallow dish, and is effected by opening and suddenly 

 closing the valves, with the posterior end in front, and thus 

 rapid progress is made. When the adductors are unbent, the 

 animal protrudes the mantle and mass of filaments, which then 

 appear too large for the shell ; this is not so, as on the slightest 

 disturbance all vanishes instantly within the valves. 



