﻿CCELACANTHID.E. 399 



Superficial ornament of irregular striae ; fin- 

 rays articulated in distal half; supple- 

 mentary caudal much elongated Diplurus (p. 409). 



No parafrontal pits ; superficial ornament of 

 irregular striae and tubercles; fin-rays 

 articulated for a long extent distally ; 

 supplementary caudal stout Undina (p. 409). 



Parafrontal and suborbital pits for enlarged 

 mucus-follicles ; otherwise resembling 

 Undina Libijs (p. 413). 



No parafrontal pits ; superficial ornament of 

 sparse tubercles, spinous on the scales ; 



supplementary caudal stout. Coccoderma (p. 415). 



B. Fin-rays long and slender, articulated only 

 for a short space distally ; supplementary 

 caudal fin apparently rudimentary or 

 absent. 



Parafrontals with pits for enlarged mucus- 

 follicles ; scale-ornament consisting of a 

 prominent median spinous tubercle, with 

 smaller tubercles above and below .... Heptanema (p. 415). 



No parafrontal pits ; superficial ornament of 



spinous tubercles Macropoma (p. 416). 



Of the genera thus enumerated, those named Graphiurus, 

 Diplurus, and Coccoderma seem least entitled to distinction, being 

 separated from Undina (so far as known) only by characters of slight 

 importance. 



Genus CCELACANTHUS, Agassiz. 



[Poiss. Foss., Feuill. 1836, p. 83, and vol. ii. pt. ii. 1844, p. 170.] 



Syn. Hoplopygus, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. 1844, p. 178. 

 Conchiopsis, E. D. Cope, Proc. Acad. Nat. Sci. Philad. 1873, 



p. 341. 

 Hhabdoderma, 0. M. Reis, Palaeontographica, vol. xxxv. 1888, 



p. 71. 



The typical genus. Teeth absent on the margin of the jaws, but 

 a few hollow, conical teeth within. Supplementary caudal fin 

 prominent ; the rays of all the fins long and slender, unjointed for 

 a considerable length proximally, closely articulated, but without 

 expansion, distally ; denticles absent upon all the rays. External 

 bones and scales superficially ornamented with series of tubercles 

 or fine ridges of ganoine. 



