400 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



multicostatus ia the collection, aud many of them have about the same number of 

 ribs, thirty-four, the maximum being about forty. On a close and careful inspec- 

 tion, however, ceitain differences appear, wliich lead to a doubt as to its identity. 



The average specimens of G. multicostatus have the valves heavy, the scars marked 

 by an elevated ridge, and almost always have more or less dark brown on the inte- 

 rior of the disk. The radiating costae are low, flat, and polished in most cases, 

 not in any observed case sculptured, and the interspaces are narrow, shallow, and 

 only crossed by incremental lines. 



In the valve above mentioned the radial costae are elevated, their upper edges 

 almost overhang the channels, and the upper surface is closely transversely threaded. 

 The channels without exception are elegantly reticulated by concentric, regularly 

 spaced, elevated lirae, about five to a millimeter. The interior of the shell is 

 pure white, the adductor scars are very Hltle raised ; there are eleven anterior 

 and thirteen posterior teeth forming a continuous arch on the hinge plate. 



Whether these differences are merely individual, or whether we have to do 

 with a species closely allied to but distinct from G. multicostatus, will require 

 much more copious material to determine. 



(C. IsODONTA.) 



Fectinacea. 



Fectinidae. 



PECTEN MuLLER, 1776. 



Having seen somewhere a statement that the name Pecten was first used in 

 a generic sense by Peter Osbeck, in his " Voyage to the East Indies and China," 

 1765, I took the trouble to hunt up the reference (p. 391, op. cit.), aud found 

 that Osbeck's name has no standing in systematic nomenclature, as no definition 

 is given and no described species is referred to it. It is a tiomen nudum, j)ure and 

 simple. From the context it is evident that the name is used colloquially, as was 

 long done by the prc-Linnean collectors, for Mu rices of the type of Murex tenui- 

 tpina with a long canal having small spines at right angles to it, which among 

 dealers and collectors was often called perten-veneiis, or Venus' comb. The first 

 to use Pecten in the modern sense was Rumph'us, in 1704, from wliom it is prob- 

 able Miillcr derived his generic name, and who preceded Osbeck by more than 

 half a century. 



PECTEN 8. s. 



Pecten sericeus Hinds. 



Pecten sericeus Hinds, Zool. Voy. Sulphur, 1844, Moll., p. 60, pi. 17, fig. 1. 



Panama Bay, 53 fathoms. Hinds. U. S. S. " Albatross," sl-'ition 3.'i68, near 

 CocDs Island, (Iiilf of Panama, in 66 fathoms, rocky bottom, temperature 58°.4 F. 

 U. S. N. Mus. 122,864. 



