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. 30].— Restoration of DipUriis vcdenciennesi. x^ 



. (From TraqTiair.) 



Fig. 302.— Outline restoration of Phaneropleuron andersoni. Upper Devonian. 

 (From Dollo, after Traquair. ) 



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

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

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



The oldest genus is 

 Bipterus^ from the 

 Old Eed Sandstone 

 of Scotland, where it 

 is contemporaneous 

 with the earliest 

 Crossopterygii and 

 also with the oldest 

 known Actinop- 

 terygii (Clieirolepis). 

 P]ianeropleuron{0\A 

 of 

 Scotland, Upper 

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

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



' Pander, Ueher die Otenodijiieriiien 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 AVoodward, Brit. Mus. Cat. Foss. Fishes, ii. 1891, p. 235 et seq. 



Fig. 303. — Dental plates of Dipterus valenciennesi, nat. 

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



nostrils ; p.p, palatine dental plates ; p.pt, palato-ptery 



goid bones ; sp, splenial teeth. (From Smith Wood- TJg^o Sandstone 



ward, after Traquair.) 



