EXPLANATION OF PLATE LII. 



Fig. 1. Empo nepwolica, Cope, head and anterior part of the body, on a block of the chalk of the Niobrara 

 beds, from Professor Merrill's collection: a, 1>, right premaxillary and dentary bones; 

 c, <i, left premaxillary and dentary bones ; e, frontal bones ; /, ectopterygoid ; g, quadrate; 

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



2. PeJecoplerus pcrmciomis, Cope, spine of pectoral fin, one-half natural size. 



3. Pectoral spine of Pdccopterus gladius, Cope, one-half natural tize ; from Professor Mudge's col- 



lection. 



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



size. 



