MOLLUSCA. 469 



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, 30 or more are 

 present upon the body of the shell where they are narrower than 

 the interspaces, the ribs upon the auriculations are narrower, 

 closer together, and more nodose than upon the body of the shell, 

 though in some examples, especially the larger ones, they are 

 inconspicuous. The surface is also marked by more or less 

 irregular, concentric lines of growth. 



Remarks. The shells which are made the types of this species 

 were identified and illustrated by Whitfield as P. tenuitestus, 

 but an examination of Gabb's type- of that species has shown 

 that Whitfield's identification was incorrect, the true P. tenui- 

 te-stus being the same as the specimens described as P. plani- 

 costatus by that author. This species differs from P. tenuitestus 

 of the same fauna, in being proportionally higher, narrower, 

 and more convex, with the radiating ribs nodose, and propor- 

 tionally broader with narrower interspaces and with the con- 

 centric markings coarser and less regular. 



Formation and locality. Navesink marl, Crosswicks Creek 

 (149, I47 3 , 195), near Jacobstown (150), Holmdel and near 

 Marlboro (Whitfield). 



Geographic distribution. New Jersey. 



Pecten cliffwoodensis n. sp. 

 Plate L., Figs. 7-8. 



Description. The dimensions of an average specimen, a left 

 valve, are : height, 30 mm. ; width, 27.5 mm. ; convexity, 4 mm. ; 

 length of hinge-line, 14 mm. The body of the shell broadly sub- 

 ovate in outline, the beaks situated a little back of the middle of 

 the hinge-line, the auriculations moderately large and sharply 

 differentiated, the anterior ones somewhat larger than the pos- 

 terior, the cardinal slopes diverging from the beak at an angle 

 of 90 or a little more, nearly straight or slightly concave, ter- 

 minating at the sides of the shell above the middle of its height. 

 The valves subequally depressed convex, the right valve if any- 

 thing slightly flatter than the left, with a moderately deep byssal 



