﻿5 Hi U'TINOPTERTGTT. 



Genus OXYGNATHUS, Egerton. 



[Figs. & Descrips. Brit. Organic Remains (Mem. Geol. Surv.), 

 dec. viii. 1855, no. 9.] 



Syn. Thrissonotus, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. 1844, p. 128 

 (undefined). 

 Cosmolepis, Sir P. Egerton, he. eit. dec. ix. 1858, no. 1. 



Trunk elegantly fusiform, more or less elongated. Mandibular 

 suspensorium oblique ; dentition consisting of a series of large, 

 well-spaced conical teeth, aud numerous minute teeth irregularly 

 arranged and somewhat clustered ; cranial roof-bones finely tuber- 

 culated, sometimes rugose, the facial bones and branchiostegal rays 

 delicately striated, and the opercular bones almost smooth. Fins of 

 moderate size or small, with very minute fulcra, the rays broad, 

 distally bifurcating, and more or less covered with a very thin layer 

 of ganoine ; the rays of the pectoral fins, except the few short ones 

 placed hindermost, articulated only at the distal extremities, all 

 others uniformly articulated to the base. Dorsal and anal fins 

 triangular in shape, somewhat longer than high, and the hinder rays 

 very short ; dorsal opposed to the space between the pelvic and 

 anal fins ; upper caudal lobe narrow and much attenuated, with 

 small ridge-scales, the fin deeply forked and equilobate. Scales 

 thick, small or of moderate size, very narrow ventrally, and orna- 

 mented with delicate oblique lines of ganoine, in part bifurcating 

 and branching, becoming very faint upon the anterior dorso-lateral 

 region and partially subdivided into tubercles. 



Oxygnathus ornatus, Agassiz. 



1844. Thrissonotus colei, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. p. 128 

 (name only). 



1854. Oxygnathus ornatus, Sir P. Egerton, Ann. Mag. Nat. Hist. [2] 

 vol. xiii. p. 435. 



1855. Oxygnathus omatus, Sir P. Egerton, Figs. & Descrips. Brit. 

 Organic Beinains (Mem. Geol. Suit.), dec. viii. no. 9, pis. ix., ix.* 



1858. Thrissonotus colei, Sir P. Egerton, ibid. dec. ix. no. 2, pi. ii. 



[Fish wanting extremity of tail ; British Museum.] 

 1877. Oxygnathus ornatus, R. H. Traquair, Ganoid Fishes Brit. Garb. 



Form. (Pal. Soc), pi. ii. figs. 2, 3. 

 1890. Oxygnathus ornatus, A. S. Woodward, Ann. Mag. Xat. Hist. [6] 



vol. v. p. 432. 



Type. Fish wanting dorsal and caudal fins ; British Museum. 

 The type species, attaining a length of about 0*4. Maximum 



