234 PALEONTOLOGY. 



The species presents much the appearance of a Chonetes in its regularly 

 rounded valve, even striae, and general characters, but shows no appearance 

 of spines on the hinge-line. We know of no species of this or any allied 

 genus from rocks of a similar age having a very close resemblance to this one. 



Formation and locality. — In the granular limestones of the age of the 

 Quebec group, Pogonip Mountain, west side, White Pine District. Col- 

 lected by A. J. Brown, esq. 



Genus PORAMBONITES Pander. 



POKAMBONITES OBSCURUS n. Sp. 

 Plate I, fig. 16. 



Shell of moderate size; irregularly transversely oval in form; a little 

 angular toward the beak, and broadly emarginate in front. Ventral valve 

 flattened-convex on the middle of the shell ; more sharply rounded near the 

 lateral margins, and strongly bent upward in front in the form of a broad 

 linguiform extension, which is rounded on the end, two-thirds as long as 

 wide, and distinctly concave on the exterior, forming an emargination in 

 the front of the valve; beak very obtuse, short, and but little curved. 

 Dorsal valve unknown, but, judging from the elevation of the front exten- 

 sion of the ventral valve, it must have been quite rotund. 



The surface of the shell is mostly exfoliated; but near the front a por- 

 tion is partially preserved, and shows what appears to have been punctate 

 lines, or striae, though they are obscure and unsatisfactory. A number of 

 concentric lines of growth are clearly distinguishable. The beak of the 

 specimen, where the shell has been removed, shows the two diverging 

 lamellae which characterize the genus Poramhonites. The specimen is quite 

 imperfect, but interesting as representing a genus so seldom recognized in 

 this country. 



Formation and locality. — In dark grayish crystalline Hmestone of the 

 age of the Quebec group, Pogonip Mountain. Collected by A. J. 

 Brown, esq. 



