212 
the inhospitable shores of the Polar seas. Attracted by the regu- 
larity of their form and the beauty of their coloring, the ancients 
distinguished them as a group from all other shells. Aristotle and 
Pliny indicated several species, and compared them to a comb or 
pecten from the similitude of their ornamental rib-formed radii. 
Distinguished artists have judged them worthy of representation 
on their canvas, and the voluptuous form of Venus is seen sup- 
ported on the waves by the valve of a pecten. A beautiful species 
which inhabits a portion of the Pacific is deified by the natives of 
some of the islands in that ocean. In Catholic countries they are 
commonly called Saint James’ shells, and the pilgrims who visited 
the shrine of St. J ames of Compostella, in Spain, were careful to 
attach one or more to their dress, collected on the neighboring 
shore, where they abound. 
It is not a little surprising that although all the earlier writers 
separated these shells from others as a natural group, yet our great 
master Linn^ placed them in his genus Ostrea, notwithstanding the 
striking difference in the structure of their animals, already indi- 
cated by Lister and others. Bruguiere corrected this error and 
restored them to the just rank of a separate genus, now universally 
acknowledged. The family of Pectinides to which it belongs is 
composed of the genera Pima., Plagiostoma, Pedum, Pecten, Hin- 
nite, Plicatula, Spondylus and Podopsis. The latter is so nearly 
related to Spondylus, and Plagiostoma so closely resembles Lima, 
that it has been proposed to suppress them both, which would leave 
but six genera. Sowerby insists that Hinnite cannot be a separate 
genus, but must be united to pecten. Of these the three first only 
are symmetrical, and furnished with a byssus. The apices of Lima 
are distant and the auricles are similar in both valves. The liga- 
ment in Pedum is inserted in a canaliform fosset on the inner face 
of the summits, prolonged into the interior. 
The ears of Pecten are equal in some species and unequal in 
others, but generally on one of the valves one of the ears is deeply 
emarginated beneath, to admit the passage of the byssus, by which 
the animal attaches itself to foreign bodies, as represented by 
Keaumer in Mem. Acad. Boyale des Sc., 1711, pi. 2, fig. 12. 
Some species have a small divergent tooth on each side of the 
cardinal fosset in one valve, and corresponding depressions in the 
opposite valve. In many species are several very small tubercles 
