154 CRETACEOUS AND TERTIARY FISH. 



Family ICHTHYODECTID^. 



Body elongate. Snout not produced. Teeth acuminate, al- 

 most or exclusively confined to premaxilla, maxilla and dentary 

 bones. Supraoccipital prominent, partly or completely separat- 

 ing parietals in median line. Squamosals reduced, otic region 

 very prominent. Parasphenoid enclosing basicranial canal. 

 Cheek-plates well developed. Mandibular suspensorium in- 

 clined forwards, but mouth gape wide. Premaxilla and maxilla 

 robust and firmly fixed, both entering upper mouth border. 

 Opercular apparatus complete, with branchiostegal rays, but no 

 gular plate. Vertebral centra well ossified, none with transverse 

 processes. Ribs nearly or completely encircling abdominal cavity. 

 Haemal arches more or less fused at base of tail. Intermuscular 

 bones present. Post-temporal bones in contact with postero- 

 lateral angles of cranium. Scales thin, cycloid. Fin-fulcra ab- 

 sent. Fin rays divided and closely articulated distally. Dorsal 

 and anal fins remote, latter elevated into an acuminate lobe an- 

 teriorly. 



Represented by about eight genera, all extinct. Possibly the 

 most salient character, as distinctive from the ChirocentridcB is the 

 anal fin having an elevated anterior lobe. 



Genus SAUROCEPHALUS Harlan. 



Saurocephalus Harlan, Journ. Acad. Nat. Sci. Phila., Ill, 1824, p. 337. Type 



Sauroceplmlus lanciformis Harlan, monotypic. 

 Saurodon Hays, Trans. Amer. Philos Soc. Phila., (2) III, 1830, p. 475. Type 



Saurodon lea Hays, monotypic. 

 Daptimus Cope, Proc. Acad. Nat. Sci. Phila., 1873, p. 339. Type Sauro- 

 ceplmlus phlebotomus Cope, specified, monotypic. 

 1 



Teeth hollow, in sockets, compressed to sharp edge in front 

 and behind. Maxillary and dentary teeth almost uniform, only 

 slightly increasing in size backwards, and those on premaxillary 

 not much enlarged. Successional teeth formed on inner side of 

 functional teeth, and a series of nutritive foramina on inner face 

 of jaw below alveolar border or inner margin of each dental 

 alveolus deeply notched. Small toothless presymphyseal bone 



