28 Colo K A DO College Studies. 



the posterior part of the ray in front of it by the basal cleft. 

 Pectoral fin composed of 15 to 20 small rays which are 

 strongly bent at the proximal ends. Caudal fin strontjly and 

 deeply forked, thou<.jh much less widely so than in either of 

 the species of Pelecorapis herein described, the lobes very 

 long and narrow, the lower a little longer than the upper. 

 The scales are large and moderately thick, subrhomboidal, 

 their vertical extent about twice the longitudinal, smooth or 

 exhibiting only delicate concentric line-sculpture, and are 

 arranged in 13 longitudinal rows on either side, the lateral 

 line- occupying the eighth row below the dorsal fin. The in- 

 termediate verterbrfB are nearly as deep as long. 



Measurements. — Those of the specimen studied by the 

 writer are: total length about 370; length of skull, measured 

 along median line to posterior limit of roof, 64; length of 

 head to posterior limits of opercular apparatus 82; tip of 

 snout to caudal peduncle 285; tip of snout to anterior limit 

 of dorsal basis 123; same to posterior preserved limit of dor- 

 sal 220; same to anterior insertion of anal fin about 250; 

 length of longest ray of anterior lobe of dorsal about 34; 

 greatest breadth of base of dorsal between exteriors of the 

 right and left integumental grooves (being that of the anterior 

 lobe) 4.5; average length of verterbrae in mid-region about 7; 

 height of scales on middle-posterior region about 9 mm. 



Occurrence. — The example studied by the writer is from 

 the Benton stage of the Platte series, in the "Fencepost 

 limestone" of the Russell substage, near Lincoln Center, 

 Kansas. Professor Cope's example was given him as hailing 

 from the "Summit of Pike's Peak"; but as that is granite, the 

 Professor deemed the specimen more likely to have been 

 derived "from the Cretaceous or possibly Jurassic beds" at 

 the foot of the peak. Later, he ascribed it to the Niobrara 

 or Fort Pierre ("Cretaceous No. 3 or 4, of Colorado"); and 

 still later, he cites an early, verbally expressed opinion of 

 his, that it was "probably of the Niobrara", adding that 

 "more full information leads to the belief that it was obtained 

 from some point in New Mexico."* 



•bee above cited Keport of Ilayden Survey, pp. 181, 182 and 273; and that of the 

 Wheeler Survey, p. 28. 



