506 FISHES CHAP. 
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 
> 
eee, 
SO 
Nee 
(From Traquair. ) 
ole 
° 
Fic, 301.—Restoration of Dipterus valenciennesi. 
Frc. 302.—Outline restoration of Phaneroplewron 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 
Dipterus, from the 
Old Red Sandstone 
of Scotland, where it 
is contemporaneous 
with the  earlest 
Crossopterygli and 
also with the oldest 
= known Actinop- 
Fic. 303.—Dental plates of Dipterus valenciennesi, nat. terygii (Cheirolepis). 
size. A, Upper jaw; B, lower jaw. 1, Position of the 
nostrils ; p.p, palatine dental plates ; p.pt, palato-ptery- Phaneropleuron(Old 
goid bones; sp, splenial teeth. (From Smith Wood- Red Sandstone of 
ward, after Traquair.) 
Scotland, Upper 
Devonian of Canada, Fig. 302), Scawmenacia (Upper Devonian 
of Canada), Ctenodus (Carboniferous of Great Britain and North 
1 Pander, Ueber die Ctenodipterinen 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, yw 235 et seq. 
