488 



FISHES 



features, and they flourished in large numbers during the Carbo- 

 niferous and Permian periods. Platysomus ranges from the 

 Lower Carboniferous to the Upper Permian in Great Britain 

 and continental Europe, and also occurs in the Carboniferous 

 of North America. Eurynotus (Fig. 285), and the singularly 

 deep -bodied Cheirodus (Fig. 286), in which pelvic fins are 

 unknown, are British Carboniferous genera. 



dect 



Fio. 286. Restoration of Cheirodus granulosus. d.ect, Dermal lateral ethmoid ; d.eth, 

 dermal mesethmoid ; d.sp, either a dermal sphenotic or a post-orbital bone ; LI, 

 lateral line ; orb, orbit. The pectoral fin is indicated in dotted outline. Other 

 reference letters as in Fig. 284. (From Traquair.) 



Fam. 3. Belonorhynchidae. The systematic position of 

 these Triassic forms is very doubtful, and it is by no means 

 clear that they are Chondrostei at all. 



Fam. 4. Catopteridae. It is very probable that this widely- 

 distributed Triassic family is an offshoot from the Palaeoniscidae. 

 It agrees with the latter in the general character of the head 

 and pectoral girdle and in the rhombic squamation, but differs 

 from its progenitors and approaches the more modern Holostei 

 in the semi-heterocercal condition of the tail, and in the approxi- 

 mate numerical agreement between the fin-rays and radialia of 

 the dorsal and anal fins. 1 



1 Smith Woodward, Brit. Alus. Cat. Foss. Fishes, iii. 1875, p. 7. 



