SUB-CLASS VI 



TELEOSTEI 



95 



Pisodus, Owen. Large hemispherical or flattened crushing teeth on the 

 parasphenoid. Closely resembling existing Albula. Lower and Middle Eocene 

 of England and Belgium. 



Family 4. Ichthyodectidae. Crook. 1 



Large extinct predaceo us fishes, with a row of strong conical teeth fixed in sockets 

 on the margin of the jaws. Upper jaw formed by short and deep premaxilla, and 

 long stout maxilla ; mandible deep, truncated in front, without any presymphysial 

 bone. Vomer and parasphenoid toothless; palato-pterygoid arch with patches of 

 small teeth. Paired fins composed of a very broad, anterior, and numerous narrower 

 rays, finely divided and articulated quite at the distal end. Dorsal fin short ami 

 remote; anal fin not much extended ; candid fin forked. Cretaceous. 



This family is very closely related to the existing Chirocentridae, of which 

 only one genus (Chiro- 

 centrus) is known, in- 

 habiting the Indian 

 Ocean. 



Portheus, Cope 

 {Xiphactinus, Leidy ; 

 Hupsodon, Ag. p.p.), 

 (Fig. 171). Powerful 

 fishes, sometimes of 

 gigantic size. Teeth 

 of variable size, oval 

 in transverse section. 

 Palatine movably 

 articulated with eth- 

 moid, with hammer- 

 shaped thickening. 

 Eye with ossified 

 sclerotic ; three sub- 

 orbital plates. Oper- 

 culum well developed 

 and large. P. molossus, 

 Cope (Fig. 171), and 

 other species occur in 

 the Chalk of Kansas, U.S.A. P. mantelli, Newton, and other species in the 

 Chalk and Gault of England, France, Belgium, Bohemia, and Saxony. 

 Fragments also in Cretaceous of Rolling Downs, Queensland. 



Ichthyodedes, Cope. As Portheus, but smaller, and teeth of uniform size. 

 Chalk of Kansas and England. 



Gillicus, Hay. Like the preceding, but teeth small and fringe-like. 

 Upper Cretaceous ; Kansas. 



Spathodactylus, Pictet. Type specimen displaying fins. Xcocomian ; 

 Voirons, Switzerland. 



1 Crook, A. It., Ueber einige Knoclientische aus der niittleren Kreide von Kansas (Palaeontogr. 

 vol. XXXIX.), 1892.- — Loom is, F. B., Die Anatoniie und die Verwandtschaft der Ganoid und 

 Knocheutisehe aus der Kreide von Kansas (Palaeontogr. vol. XLVI.), 1900. — Stewart, A.. Teleosts 

 of the Upper Cretaceous (Univ. Geol. Surv. Kansas, vol. VI.), 1900. 



Fig. 171. 



Head of Portheus molossus, Cope. Niobrara Cretaceous ; Fox Caiion, 

 Kansas. ] 4 nat. size (after Cope). 



