370 



FISHES. 



Sandstone — Ghirolepis and Acrolepis ; from Carboniferous 

 rocks — Oosmo;ptychius, ElonicMhys, Nematoptychius, Cyclopty- 

 chius, Microconodus, Gonatodus, Bhadinichthys, Myriolepis, 

 Urosthenes ; from the Permian — Bhabdolepis, Palceoniscais, 

 Amhlypierus and Pygopterus ; from the Lias — Gentrolepis, 

 Oxygnathus, Gosmolepis, and Thrissonotus. 



[See Traquair, " The Ganoid Fishes of the British Carboiuferous Forma- 

 tions." Part I. Palwonisddm.^ 



Seventh Family — Platysomid^. 



Body generally high, compressed, 'covered with rhombic ganoid 

 scales arranged in dorso-ventral hands. .Notochord persistent, 

 with the vertebral arches ossified. Heterocercal ; fins with 

 fulcra; dorsal fin long, occupying the posterior half of the 

 back. Branchiostegals numerous. Teeth tubercular or obtuse. 



Fig. 147.^Platysomus gibbosus. 



Extinct. From Carboniferous and Permian formations — 



Eurynotus, Benedenius, Mesolepis, Burysomus, Wardichthys, 



Ghirodus (M'Coy), Platysomus. 



[See Traquair, "On the Structure and Affinities of the Platysomidae, in 

 "Trans. Eoy. Soc,,"- Edinb., vol. xxix.] 



EIGHTH SUB-OEDEE— AMIOIDEI. 



Vertebral column more or less completely ossified, hetero- 

 cercal. Body covered with cycloid scales. Branchiostegals 

 present. 



