590 SYSTEMATIC PALEONTOLOGY 



margin, and perceptibly narrowing below; posterior shorter on the car- 

 dinal line than below; anterior side marked by seven sharply-elevated 

 nodose rays, and the posterior by six, with one or two smaller ones between, 

 near the body of the shell. Body of the shell marked by about thirty to 

 thirty-five slender, rounded but unequal rays with much wider flattened 

 interspaces, with an occasional incipient ray on the outer third of the 

 shell. Ribs marked by distant, elevated or subspinose nodes, most closely 

 arranged on the auriculations and obsolete above the middle of the body 

 of the valve. Right valve with the ribs proportionally stronger in the 

 specimens examined than on, the left valve and showing a stronger ten- 

 dency to alteration of smaller and larger ones than on the opposite, while 

 the imbrications of the ribs are not nearly so strong, not rising into spines, 

 as on the left valve. Auriculations of the right valve scarcely perceptibly 

 radiate, while the concentric markings of the valve are more subdued 

 throughout. 



" So far as I have discovered the species was never figured by its author, 

 but its description is more full than usual, so I think the identification is 

 less Mkely to be questionable than in some other instances. It would seem 

 to be the type of Pecten islandicus, although the ribs are less closely 

 arranged and the interspaces are flattened. Among the few specimens 

 which I have examined I have seen no reason to suppose the valves were 

 so strongly bent as to leave them ' about half an inch apart in the middle/ 

 as the author states. 



"Formation and Locality. In the Lower Green marls at Holmdel, 

 New Jersey, collected at G. C. Schanck's pits, near Marlborough, and pre- 

 sented to the New Jersey collection by the Rev. Dr. Riley. It also occurs 

 at Burlington, New Jersey." Whitfield, 1885. 



" Shell, exclusive of the auriculations, broadly ovate in outline, higher 

 than wide, the dimensions of a left valve being: height 40 mm., width 

 35 mm., convexity 5 mm., length of hinge-line about 16 mm. Left valve 

 depressed convex, deepest above the middle, the beak pointed, auriculations 

 of moderate size, the anterior one larger than the posterior. Surface 

 marked by low, rounded, nodose, more or less unequal, radiating ribs, 

 which increase by intercalation, thirty or more are present upon the body 



