62 



PISCES 



CLASS I 



Uronemus, Ag. (Ganojmstodus, Traq.). Body laterally compressed, with 

 small and very thin scales, which are faintly striated. Paired fins acutely 

 lobate. Dorsal fin arising shortly behind the head. U. lobatus, Traq., from 

 Lower Carboniferous (Calciferous Sandstones), Burdiehouse, near Edinburgh. 



Conchopoma, Kner. Lower Permian ; Ehenish Prussia. 



Family 2. Ctenodontidae. Traquair. 



A pair of dental plates on the palatine bones, and an opposing pair on the 

 splenials ; these plates usually retaining traces of their component denticles. Jugidar 

 plates usually present. Tail diphycercal or heterocercal. 



Dipterus, Sedgw. and Murcl]. (Catopterus, Polyphracttts, Ag.), (Figs. 114, 

 115). Small fishes. Bony plates of head covered with punctate ganoine, 

 but cranium apparently quite cartilaginous. Base of cranium covered with a 



Dipterus valcnciennesi, Sedgw. and Murcli. Restoration, 1/3 nat. size. 

 Lower Old Red Sandstone ; Banniskirk, Orkney (after Pander). 



broad, rhombic parasj^henoid {PSph), which is flanked on either side by a 

 pterygo- palatine (P) extending forwards into a triangular pointed plate, 

 which serves as base for a large triangular tooth (d) bearing tuberculated 

 ^ radiating ridges. The two palatine bones meet in 



the middle in a straight line. The mandible is com- 

 pletely ossified, with a single, large dental plate on 



p^;,7, A^, 



Dipterus valenciennesi, Sedgw. and M. Lower Old Red Sandstone ; Banniskirk. A, Roof of skull. B, Im- 

 perfect palate (PSph, Parasplienoid ; P, Pterygo - palatine, accidentally divided into two pieces beliind by a 

 broken line ; d, Palatine tooth). C, Imperfect mandible with tooth (d), after Pander). 



the splenial of each side, and its tuberculated ridges radiating fan-like from 



