HOLOSTEI 



499 



predaceous Fishes, with pointed teeth, rhombic scales, short dorsal 

 and anal fins, a single jugular plate and prominent fulcra. The 

 vertebral centra are represented by distinct hypo -and pleuro-centra, 

 which may form complete alternating rings in the tail. 



The family first appears in the Trias and ranges throughout 

 the Jurassic period. Eugnathus (Jurassic) and Eurycormus 

 (Upper Jurassic). Caturus (Fig. 294) has a more extensive 

 range, occurring in the Upper Trias of the Tyrol and in the 

 Upper Jurassic of England and Bavaria. Caturus and Eury- 

 cormus, with their relatively thin, imbricated, cycloid scales, 

 which have lost the peg-and-socket articulation, form connecting 

 links between the more typical Eiiynathus and the Amiidae. 



FIG. 294. Restoration of Caturus furcatus, omitting the squamation. x fa 

 Upper Jurassic of Bavaria. (From Smith Woodward.) 



Fam. 5. Amiidae. Body fusiform and somewhat compressed. 

 Scales uniformly thin, cycloid, and imbricated. Single dorsal fin 

 long and low. Anal fin short. Tail nearly homocercal, with a 

 rounded hinder margin. Fulcra absent from all the fins. 

 Moderately large conical teeth are present on the premaxillae, 

 maxillae, palatines and dentaries, and smaller teeth on the 

 vomers, pterygoids, splenials and parasphenoid. Pre- and post- 

 centra fused in the trunk, forming complete bony amphicoelous 

 centra, but distinct in the tail. A single large jugular plate is 

 present. In the solitary living species the air-bladder is cellular, 

 and its afferent arteries are derived from a posterior aortic arch. 

 Pyloric caeca absent. Two peculiar comb -like structures are 

 present on the throat. 



The Bow-Fin (Amia calva), the sole existing representative of 

 the family, is abundant in the rivers and lakes of Central and 

 Southern North America, including the great lakes Huron and 



