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 macropomiis. 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.^ 

 — Fishes with fusiform bodies, 

 short dorsal and anal fins, 

 and usually with a complete 

 investment of articulating 

 Fig. 284.— Outline restoration of tiie skull and rhombic, rarely cycloid, ganoid 



secondary pectoral girdle of Palaeoniscus gcales fFiff. 283). Fulcra 

 macropomus. are, Angular ; dr. r, branchio- 



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



deutary ; d.ect, dermal lateral ethmoid ; /, ^f ^l-^g median finS, and CSpCci- 

 frontal ; i.ci, mfra-clavicle ; %.op, snooper- ^ 



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



culum ; or, orbit ; p parietal ; p.f, pectoral j-j^g ^^^^j^ ^ohQ. Eibs 



fan ; p.mx, premaxilla ; y.o^, preoperculum ; ^^ 



p.<, post-temporal ; s.rf, supra-ciavicie ; s.o, are not known to be present. 



circumorbitals ; sq, squamosal : the single en n • i. j i 



median bone oVeriying the short rostrum ^^uU mVCStcd by a Very COm- 



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



one intercalated between the squamosal i , . , . , -, 



and post-temporal a supra-temporal. The "OneS, WhlCh m number and 



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

 Traquair.) i m i /t-i- 



normal leleostome type (lig. 

 284). The secondary upper jaw includes both premaxillae and 

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



' Traquair, Monogr. Palaeont. Soc. 1877 ; Quart. Journ. Qcol. Soo. xxxiii. 1877 ; 

 Trans. Soy. Soc. Edinl. xxx. 188.3, p. 22 ; Ann. May. Nat. Hist. (4) xv. 1875, 

 p. 237 ; Smith Woodward, Mem. Gcol. Surv. N. S. Wales, Palaeont. No. 4, 1890, 

 and No. 9, 1895. 



