EASTMAN: CATALOG OF FOSSIL FISHES IN CARNEGIE MUSEUM. 359 



position, and ornamentation of the median fins. Anterior portion of the body 

 unknown. 



Type. — Posterior portion of large fish; Carnegie Museum, Cat. No. 4748. 



It is unfortunate that the complete form of the body is unknown in the species 

 under discussion, which is founded upon an imperfectly preserved and somewhat 

 distorted caudal portion of a fish considerabh^ exceeding U. penicillata in size, and 

 approximating U. gulo. In so far as the number of rays supporting the lobes of 

 the principal caudal fin may be relied upon as a differential character, the new species 

 presents the following contrast to its congeners: 



Name of Species. Number of Caudal Fin-rays. 



Undina gulo (Egerton) 16-18 above and below. 



penicillata Miinster 18-20 " 



" cirinensis Thiolliere 15 " ; 13 " 



" grandis Eastman 25 " ; 19 " 



The supplementary caudal fin in the form under discussion is relatively shorter, 

 that is, less produced backwards, than in other species, and comprises eleven flexed 

 and articulated rays above and below. A noteworthy feature is that the rays of 

 the principal caudal are provided along their expanded lateral surface with a series 

 of minute conical denticles, similar to those occurring along the posterior border 

 of the dorsal fin-rays of certain species of Macrosemius. The rays of all the fins 

 are acutely pointed at their distal extremities. The posterior dorsal and anal fins 

 comprise each about fifteen rays, are more acuminate than in other species, and 

 arise nearer the base of the caudal fin. The position of the pelvic and pectoral 

 pair is indicated in the type-specimen, and the pair of elongated and slender basi- 

 pterygia, which are apparently fused, where they meet in an expanded distal process, 

 are well displayed. 



The axis is remarkably broad, tapers gradually posteriorly, but becomes 

 expanded in the region of the articulated portion of the caudal fin-rays, after which 

 it again tapers, being continued to the tip of the supplementary caudal fin. The 

 lateral line is prominent, and runs parallel with the cartilaginous axis. None of 

 the scales display the outer surface satisfactorily, but appearances suggest that 

 the external ornament consisted of rather sparse and discontinuous ridges of ganoine, 

 directed more or less longitudinally or slightly radiating. The covered portion of 

 the scales is marked by numerous delicate concentric striae crossed by another fine 

 series having a fan-shaped arrangement. In U. gulo and U. penicillata the scales 

 are externally ornamented with numerous closely spaced elongated tubercles; and 

 in U. cirinensis the scale characters are thus described by the original author : 



