PECTEN. 49 
The foot emits a powerful coarse byssus, which cannot be 
detached without laceration of the body, but the strands are 
easily separated from the substances on which they are fixed ; 
this is contrary to the usual plan of the Bivalves, which, when 
a change of locality takes place, is effected by drawing the 
byssus from that part of the foot-groove close to the body, 
and leaving it moored to the substance on which it was fixed - 
this operation we have witnessed even in confinement. This 
species is given as an example of the variation of specialties ; 
all the others afford nearly as decided ones. 
I trust that some northern observers will compare the P. 
tigrinus, P. striatus and P. furtivus, all of which we believe 
are identical, and communicate the result: if they are distinct, 
malacologists will have no difficulty in seizing the distinctive 
characters. Speaking conchologically, we should say that the 
three so-called species are only variations of the old P. odso- 
fetus of authors, now styled P. tigrinus. 
This species is either free, or adheres by the byssus to 
marine substances, but is not imbedded in them by the under 
valve, as in the P. pusio. 
P. pusto, Pennant. 
P. pusio, Brit. Moll. ii. p. 278, pl. 50. f. 4, 5, and pl. 51. f. 7. 
P. distortus, Montagu. 
P. sinuosus, Turton et Auct. 
The body and ovary throughout are either intense vermi- 
lion, or of a uniform pale yellow-white, and not half white 
and half vermilion, as in P. opercularis; at least in P. pusio 
we have never observed this to be the case. The branchi 
are dull red-brown, and the palpi pale brown; there are two 
connecting rows of pale red cirrhous fringe around the mouth. 
The back or free margin of the reflected mantle has two to 
three rows of irregular, short, yellow-white, blunt filaments. 
The ocelli are larger, fewer, and more distant than in the 
type. The fixed or anterior marginal circle has a row of 
large, long, conical, pointed, yellow filaments, and in front 
of it two to three irregular rows of shorter cirrhi of different 
E 
