COPE ON ICHTIIYIC FAUNA OF THE GREEN RIVER SHALE?. 809 



prominent. In section II, the scuta are not wider tlian long', and have 

 but one, a median tooth, which is the extremity of a median longitud- 

 inal carina. The species of section I are D. dentatiis, I), analis^nnd D. 

 pectorosus ; those of section II are D. humilis and D. alius. 



Char, specif. — Fin-radii: D. I — ISj A. I. 35. Yertebr?e: dorsal, 18,* 

 caudal, 21. The greatest depth enters the length without the caudal 

 fin two and a half times, and the head enters the same nearly three and 

 one-third times. The eye is large, its horizontal diameter a little exceed- 

 ing the length from its border to the inferior edge of the premaxillary 

 bone, and a little greater than one-fourth the length of the head. The 

 premaxillary and dentary bones are short and deep, the latter with a 

 deep notch on the anterior border 5 both are directed upward. The 

 maxillary bone is long and narrow, and curved backward at its lower 

 end, which reaches a. point below the anterior border of the orbit. The 

 profile behind the premaxillary bone is nearly horizontal; above the 

 posterior part of the orbit, it rises, and a compressed supraoccipital 

 crest carries it to the gently convex dorsal line. The abdomen is con- 

 vex, and is about as long as the caudal region. The last dorsal ray rises 

 above a point anterior to the first anal ray. The caudal is deeply 

 forked. The ventrals originate at a point barely in advance of a verti- 

 cal line from the first dorsal ray. The pectoral fins are short. The 

 scuta of the inferior median line are large and acute. The scales are 

 rather small, and are delicately grooved; twenty rows may be counted 

 between the vertebral column and the dorsal fin. 



Measurements. 



M. 



Totallength 0.365 



Length of head : 0.083 



Lenoth (axiiil) to below first dorsal ray 0.145 



Length to above first anal ray 0.185 



Length to base of external caudal rays - 0.285 



Depth at orbit , 0.055 



Depth. at occiput 0.093 



Depth at first dorsal ray 0.113 



Depth at middle anal ray 0.050 



Depth at base of caudal fin 0.030 



This species is represented by a single specimen of the size of a small 

 Shad and exceeding the Herring. It is in fine preservation. 



•Diplo:mystus analis. Cope, sjp. nov. 



Eadial formula : D. I. II ; A. I. 40. Vertebriie : dorsal, 17-18 ; caudal, 

 23-24. This species is more elongate in i;)roportion to its depth than 

 either of the other species, the' length being three times the greatest 

 depth. The anal portion of the body is considerably longer than the 

 abdomen, and the anal fin is long and with short rays. The ventral fin 

 commences well in front of the dorsal, whose last ray is considerably in 

 advance of the first anal ray. The pectoral fin reaches the ventral, and 



