36 Colorado College Studies. 



and is well elevated, attaining a height equal to about two- 

 thirds of that of the pectoral fin. The pectoral, which is 

 preserved entire, is subinferiorly placed, large, and if in 

 appressed position, would reach more than one-third of the 

 distance from the insertion of its anterior ray to the begin- 

 ning of the anal fin; it is composed of 16 strong and slender 

 and of about 4 posterior short and feeble rays, of which both 

 the first, which is simple, and the following or dissected rays 

 are articulated. The pelvic fin is not preserved, nor its 

 position indicated. The anal fin is represented by rather a 

 long insertion at the front of which and preceding (or partly 

 embracing?) it are preserved six (more, perhaps originally) 

 overlapping pairs of bony scutes similar to those described 

 as embracing the base of the dorsal fin in Pelecorapis varius. 

 The caudal fin, which is large, is strongly forked, much more 

 widely so than that of Sijllanniis latifrons, its lobes long and 

 narrow, lanceolate, though considerably less slender than 

 those of tlieStjlkemHs. Vertebrae estimated to exceed 50; ribs 

 well developed. Scales ctenoid, very small, much smaller 

 than those of Pelecorapis varius relatively to size of body, 

 estimated to form about 60 longitudinal rows on either side 

 of the body, there being about 6 scales in 6 mm. in any of 

 the oblique rows on the middle of the flank, glistening, seen 

 under the hand-lens to be ornamented each with three or four 

 coarse, strongly accentuated, concentric undulations on the 

 anterior part and with several less pronounced, longitudinal 

 or subradiate grooves on the posterior part, the posterior 

 margins being toothed. I am unable to detect any trace of a 

 lateral line on the parts on which scales are preserved, but 

 these represent but a small portion of the surface and do not 

 include the region in which the lateral line is known to be 

 developed in Pelecorapis vai'ius. 



Measurements. — Length from insertion of anterior ray of 

 pectoral to extremity of tail 388; from same to beginning of 

 anal scutes 173; from same to point under insertion of first 

 (or first preserved) ray of dorsal fin about 85; maximum 

 height about 60; length of upper lobe of tail, measured from 

 caudal isthmus, about 90; its breadth, midway of same length, 



