BULLETIN OF THE UNITED STATES FISH COMMISSION. 
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B.— NATURAL HISTORY OF THE GIANT SCALLOP. 
1.— TEE COMMON AND SCIENTIFIC NAMES. 
The large pecten of which this paper treats is known among fishermen and 
others by several names. In localities in which it is the only representative of the 
genus it is called simply “ scallop.” In other sections, where the small scallop {Pecten 
irradians) is also found, the designations “ giant scallop ” and “ great scallop ” are 
given with reference to its size, and “ smooth scallop ” to distinguish it from the con- 
spicuously crenated shell of the common species ; the latter name also suffices to dif- 
ferentiate it from the strongly-ribbed valves of P. islandicus, a comparatively large 
deep-water form occurring in abundance off the same coasts adjacent to which the 
smooth species is found. The name giant scallop is herein adopted as being expres- 
sive and appropriate. Oapt, J. W. Collins states that at places on Penobscot Bay 
the fishermen call the species the “ hen clam.” 
The species, or a very closely related form, was first described by Say as a fossil 
from the Miocene of Virginia and called Pecten clintonius. Under various other names * 
recent specimens were described by Lamarck, Mighels, Linsley, Stimpson, and others. 
It is now held by some writers that the fossil and living forms are identical, and 
the name advanced by Say in 1824 has consequently been adopted by them. The fol- 
lowing remarks on this subject are by Professor Yerrill : 
A comparison of specimens of this Miocene species, from Sarrey, Virginia, with the more strongly 
ribbed, deep-water form hitherto recorded by me as Pecten teuiiicostatus, var. aratus, shows that they are 
in all respects essentially identical. In the fossil specimens the ribs are much stronger and more regu- 
lar thau in ordinary specimens of P. tenuicostatus, but not more so than in many deep-water specimens 
taken in 65 to 125 fathoms, off Martha’s Vineyard ; while among the numerous specimens dredged by 
us, all gradations [occur] between the strongly ribbed form and those forms common in shallow 
water, in which the ribs are much more slender, indistinct, or almost obsolete. The forms of the 
main shell and of the auricles are the same, however, in all these varieties. The fossils, like all the 
recent specimens, show the peculiar fine, oblique strise or vermiculations between the ribs, both on the 
body of the shells and on the auricles. In the fossil specimens the ribs, especially those towards the 
ends of the shell and on the auricles, are crossed by the raised lines of growth in such a way as to 
form small, rather close, distinctly arched, raised scales ; this character, which is not usually seen in 
the smoother, shallow-water form is found in many of the deep-water specimens quite as prominently 
or even more so than in the fossils. 
There being no doubt, therefore, of the identity of the fossil and the recent shells, the name Clinto- 
nius should be adopted for this species, on account of its priority, while the name tenuicostatus may 
well be retained to designate the ordinary smoothish, mostly shallow-water variety, found on the New 
England coast. This name was originally given by Dr. Mighels to very young specimens of this 
smoothish variety, under the impression that they were a distinct species, but he afterwards recog- 
nized the fact that they were only the young of the common species, at that time generally known as 
the Pecten magellanicus Lam.t 
* The principal synonymy of the scallop is as follows : 
Pecten clintonius Say, Jour. Acad. Nat. Sci. Phil., iv, 1824, p. 124, pi. 9, fig. 2. 
Pecten tenuicostatus Mighels, Proc. Best. Soc. Nat. Hist., i, p. 49, 1841 (young). This is the 
preferred name in most recent works. 
Pecten fuscus Linsley, Amer. Jour. Sci., xlviii, p. 278, 1845. 
Pecten magellanicus Lamarck, Anim. Sans. Vert., ed. ii, vol. VII, p. 134. 
Pecten hrunneus Stimpson, Shells of New England, 1851. 
Pecten principoides, Emmonds, Report N. C. Geol. Survey, 1858, p. 280, fig. 198. 
t Trans. Conn. Acad., vol. vi. Catalogue of Mollusca of New England Coast, part 1, pp. 260-2S1. 
