56 Isospondyli 



posterior without spines. The mesocoracoid is present as in 

 ordinary Isospondyli. Gonorhynchus abbreviates occurs in 

 Japan, and Gonorhynchus gonorhynchus is found in Australia and 

 about the Cape of Good Hope. Numerous fossil species occur. 

 Charitosomus lineolatus and other species are found in the Cre- 

 taceous of Mount Lebanon and elsewhere. Species without 

 teeth from the Oligocene of Europe and America are referred 

 to the genus Notogoneus. Notogoneus osculus occurs in the 

 Eocene fresh-water deposits at Green River, Wyoming. It 

 bears a very strong resemblance in form to an ordinary sucker 

 (Catostomus), for which reason it was once described by the 

 name of Protocatostomus. The living Gonorhynchidas are all 

 strictly marine. 



In the small family of Cromeriidcz the head and body are naked. 



The Osteoglossidae. Still less closely related to the herring 

 is the family of Osteoglossidce, huge pike-like fishes of the tropical 

 rivers, armed with hard bony scales formed of pieces like mosaic. 

 The largest of all fresh-water fishes is Arapaima gigas of the 

 Amazon region, which reaches a length of fifteen feet and a 

 weight of 400 pounds. It has naturally considerable commer- 

 cial importance, as have species of Osteoglossum, coarse river- 

 fishes which occur in Brazil, Egypt, and the East Indies. 

 Heterotis nilotica is a large fish of the Nile. In some or all 

 of these the air-bladder is cellular or lung-like, like that of a 

 Ganoid. 



Allied to the Osteoglossidcz is Phareodus (Dapedoglossus), 

 a group of large shad-like fossil fishes, with large scales of 

 peculiar mosaic texture and with a bony casque on the head, 

 found in fresh-water deposits of the Green River Eocene. In 

 the perfect specimens of Phareodus (or Dapedoglossus} testis the 

 first ray of the pectoral is much enlarged and serrated on its 

 inner edge, a character which may separate these fishes as a 

 family from the true Osteoglossidce. It does not, however, 

 appear in Cope's figures, none of his specimens having the 

 pectorals perfect. In these fishes the teeth are very strong 

 and sharp, the scales are very large and thin, looking like the 

 scales of a parrot-fish, the long dorsal is opposite to the anal 

 and similar to it, and the caudal is truncate. The end of the 

 vertebral column is turned upward. 



