5o6 



FISHES 



always distinct, the remaining median fins are either distinct or 

 continuous. Dental plates traversed by radiating transverse 

 ridges terminating in rows of conical denticles (ctenodont 



FIG. 301. Restoration of Dipterus valenciennesi. xi. (From Traquair.) 



FIG. 302. Outline restoration of Phaneropleuron andersoni. Upper Devonian. 

 (From Dollo, after Traquair.) 



dentition, Fig. 303). Voinerine teeth not known. Cranial bones 

 numerous and small, and, like the squamation, with or without 

 an investment of ganoin. Jugular plates present or absent. 1 



The oldest genus is 

 Dipterus, 2 from the 

 Old Red Sandstone 

 of Scotland, where it 

 is contemporaneous 

 with the earliest 

 Crossopterygii and 

 also with the oldest 

 known Actinop- 



FIG. 303. Dental plates of Dipterus valenciennesi, nat. fcervoii ( CheiToleVlS] 



size. A, Upper jaw ; B, lower jaw. n, Position of the . ^ 



nostrils ; p.p, palatine dental plates ; p.pt, palato-ptery- Phaner0pleuron(0ld 



goid bones; sp, splenial teeth. (From Smith Wood- p or i Qonr1ofr.no /->f 

 ward, after Traquair.) 



Scotland, Upper 



Devonian of Canada, Fig. 302), Scaumenacia (Upper Devonian 

 of Canada), Ctenodus (Carboniferous of Great Britain and North 



1 Pander, Ueber die Gtenodiplerinen des Devonischen Systems, St. Petersb. 1858. 



2 Traquair, Ann. Mag. Nat. Hist. (5), ii. 1878, p. 1 ; Geol. Mag. (3), vi. 1889, 

 p. 97 ; Smith Woodward, Brit. Mus. Cat. Foss. Fishes, ii. 1891, p. 235 et seq. 



