486 



FISHES 



the other hand, there are certain features in the Catopteridae 

 which indicate an approach to Fishes of an altogether more modern 



FIG. 283. Palaeoniscus inacropomus. Restoration, nearly one-half nat. size. 

 (From Traquair. ) 



type- 



Finally, the Chondrosteidae represent a stage in a career 



of degeneration, the climax 

 of which is reached by the 

 modern Polyodontidae and 

 Acipenseridae. 



Fam. 1. Palaeoniscidae. 1 

 Fishes with fusiform bodies, 

 short dorsal and anal fins, 

 7- P .f and usually with a complete 

 <' rr f _;, investment of articulating 



FIG. 284. Outline restoration of the skull and rhombic, rarely cycloid, ganoid 



secondary pectoral girdle of Palaeoniscus scales (Fig. 283). Fulcra 

 macropomus. an, Angular ; br. r, branchio- ._ i 



stegai rays ; d, clavicle (cieithrum) ; d, generally present at the bases 



dentary ; d.ect, dermal lateral ethmoid ; /, Q f fa Q me dian fins, and CSpeci- 

 frontal ; i.d, infra-clavicle; i. op, suboper- 



culum ; mx, maxilla ; n, nostril ; op, oper- ally along the dorsal border of 



culum ; or, orbit ; f ,, parietal ; p.f, pectoral the Upper Caudal lobe. Klbs 

 fin ; p.mx, premaxilla ; p.op, preoperculum ; - *- 



p. t, post-temporal ; s. d, supra-ciavicie ; s.o, are not tnown to be present. 



circumorbitals ; sq squamosal ; the single gk R invegted b ye com . 



median bone overlying the short rostrum J _ J 



is probably a dermal mesethmoid, and the plete Series of paired dermal 



bones - which in number and 



dotted lines indicate sensory canals. (From disposition Conform to the 



normal Teleostome type (Fig. 



284). The secondary upper jaw includes both premaxillae and 

 large maxillae ; and, as a rule, both the dentary and splenial bones 



1 Traquair, Monogr. Palaeont. Soc. 1877 ; Qiiart. Journ. Geol. Soc. xxxiii. 1877 ; 

 Trans. Roy. Soc. Edinb. xxx. 1883, p. 22 ; Ann. Mag. Nat. Hist. (4) xv. 1875, 

 p. 237 ; Smith Woodward, Mem. Geol. Sure. N. S. Wales, Palaeont. No. 4, 1890, 

 and No. 9, 1895. 



