Perip. 



624 



Periplectrodus warreni. {Figures under P, compressus.) 

 St. John & Worthen, Geo. Sur. 111., Vol. 6, 1875, page 325, plate 

 8, iigs. 25 a^to G'j the last a mature specimen of this species of 

 fish- tooth, showing at least seven transverse^ series of crown- 

 cusps, with fine cutting edges, and ornamented on both faces, 

 much as in Cladodus. A score of such have been found, of 

 various ages, and a great variety in number of sets of cusps, 

 showing that old ones may have up to twelve. From the Il- 

 linois Burlington (Suh-cari.) limestone, XL 



Pernopecten crenulatus. {Pecten crenulatus,) Hall, 

 ^^*«^ Geology of the Fourth District of New York, 



?• ■JiiillL 1843, page 264, fig. 119,8. Chemung forma- 



tion, VIII g. 



Pernopecten glaber. {Limaglaher,) Hall, page 264, fig. 

 119,10. Chemung formation, VIII g. 



H 



Pernopecten obsoletus. {Lima olsoleta,) Hall, page 

 Vni.5. 264, fig. 119,11. Chemung formation. VIII g. 



Pernopecten shumardianus {Entolium shumardianum^ 

 Winchell. Proc. Acad. Nat. Sci. Philada., 1865).— Pal. Ohio, 

 Vol. 2, 1375, page 292, plate 15, fig. 4 a, I, Waverlg forma- 

 tion^ X, 



Petalodus alleghaniensis, Leidy. Journal Acad. N. S. 



,3 ^ Phila. [2] Vol. 3, 1856. 



_'— Pal. Ohio, Vol. 2, 



"^ 1875, page 52, plate 58, 



fig. 13 <2, front face of 



average specimen ; 13 



"^ciLOh'ip.llW pi.LVWi . a^ front face of small 



