EXPLANATI(3N OF PLATE LII. 



Fig. 1. Empo nepwolka, Cope, bead and anterior part of the body, on a block of tbe cbalk of the Niobrara 

 beds, from Professor Merrill's collection: a, ft, right preniaxillary and dentary bones; 

 c, d, left premaxillary and deutary bones ; e, frontal bones ; /, ectopterygoid ; g, quadrate; 

 h, denual scuta; i, pectoral fin ; one-half natural size. 



2. Pelecopterus pernicioms, Cope, spine of pectoral fin, one-half natural hize. 



3. Pectoral spine of Pelecopterus gladius, Cope, oue-hnlf natural ."ize ; from Professor Mudfje's col- 



lection. 



4. Beryx insciilptiis, Cope, from Dr. Lockwood's collection, one-half natural size; a, scales, natural 



Bize. 



