82 A. JE. Verrill — Study of the family Pectinidce. 



iipper valve. The sculpture, when any is present, is nearly the same 

 on both valves. 



The auricles are straight and rather short, the posterior one is 

 broad and obtuse-angled. The byssal notch is small and the pecti- 

 nidial teeth are obsolete, or nearly so. There are no internal ribs ; 

 the inner surface is slightly pearly. The hinge-plate has only one 

 longitudinal rib, just below the ligament ; it is ci'ossed by numerous 

 line, transverse incisions, often more developed than in allied sj^ecies. 

 The sculpture, when evident, consists of fine lines of growth, and 

 sometimes of very delicate, 'straight, radial riblets, without campto- 

 nectes sculpture. 



According to Jeffreys, the ocelli are few in number, about six or 

 eight in the front i"ow and about twice as many in the second row. It 

 swims about for a long time and then quickly anchors itself by a 

 small byssus. 



It occurs in 15 to 200 fathoms on the northern European coasts. 



Camptonectes Grcenlandica (Sow.) Verrill. 



PerJen Grcenlandicus Sowerby, Thes. Conch., p. 57. pi. 13, fig. 40. G. 0. Sars, 

 Moll. Reg. Arct. Norveg., p. 23, pi. 2, figs. 4, a-c, 1878. 



The shell is rounded, inequivalve, very thin, hyaline, nearly 

 smooth, often with a violet iridescence when fresh. The left valve 

 is covered, even from the nucleus, with fine microscopic campto- 

 nectes sculpture, in the form of thin, raised, divergent riblets, more or 

 less irregular and wavy, most visible by translucency. The left 

 valve sometimes has, also, fine radial striae and delicate lines of 

 growth. The margins are thin and smooth, that of the right valve 

 turns up a little against the other, which is larger, and the valves 

 close very tightly, so that anteriorly there is scarcely any visible 

 gape, even at the byssal notch, or at the end of the auricle. The 

 byssal notch is well-marked and the pectinidial teeth are small and 

 few. The byssus is probably very slender. 



The auricles are not oblique and are nearly equal. The hinge- 

 plate is very thin ; the single longitudinal ridge is scarcely visible. 



A row of six or seven ocelli can be seen through the shell in alco- 

 holic specimens. 



Off Newfoundland, in 130 to 224 fathoms. Off northern Europe 

 and in the Arctic Ocean. 



