226 PAL^ONTOLOaY OF NEW JEESEY. 



The species somewhat resemble P. tenuitestus Gabb, from the lower 

 marls, in its surface markings, but is proportionally broader across the body 

 of the shell. The young specimen, especially those with fewer ribs, are 

 very similar in form and general appearance to P. venustus Conrad, also 

 from the lower marls, but they have usually a greater number of ribs. 



Formation and locality. — In the upper layers of the Upper Marls at 

 Shark River. All the specimens which I have seen are from the collection 

 at Rutgers College, except one, figured, which is in the collection of the 

 Academy of Natural Sciences of Philadelphia. 



Pecten Rigbyi, u. sp. 

 Plate XXIX, Fig. 6. 



Shell small, circular in outline exclusive of the auriculations, and mod- 

 erately ventricose on the right valve; ^ars rather large, the anterior one 

 nearly twice as long as wide, and the byssal notched below it deep; pos- 

 terior ear nearly or quite as long, but shorter on the hinge-line than where 

 it joins the body of the valve, making the hinge-hne a little more than half 

 as long as the width of the body of the shell below. Surface of the shell 

 marked by from twenty-two to twenty-six radiating ribs, which are strong 

 in the middle of the valve and gradually decrease in strength toward the 

 sides. Surface of the ribs crossed by very distinct, imbricating, concentric 

 lamellae. Auriculations on the right valve both marked with radiating ribs 

 and comparatively strong concentric lamellose lines. Left valve unknown. 



This species is associated with Pecten Kneiskerni Conrad, but may be 

 distinguished from that one by the comparatively coarser radiating ribs. 



Formation and locality, — In the upper layer of the Upper Marls, at Shark 

 River, New Jersey. 



Avicula annosa Conrad. 

 Plate XXIX, Fig. ,9. 



Avicula annosa Conrad. Am. Jour. Conch., Vol. I, p. 214, PI. XX, Fig. 16. Smith- 

 sonian Check-list, Eocene Fossils, p. 4. Meek, Geol. Surv. K J., 1868, p. 731. 



The typical specimen of this species is before me, but it is such an 

 imperfect cast that it is difficult to ^determine satisfactorily as to its true 



