282 Isospondyli 
posterior without spines. The mesocoracoid is present as in 
ordinary Jsospondyli. Gonorhynchus abbreviatus 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 Gonorhynchide are all 
strictly marine. 
In the small family of Cromeriid@ the head and body are naked. 
The Osteoglossida.—Still less closely related to the herring 
is the family of Osteoglosside, 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 4oo 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 Osteoglosside 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 Osteoglosside. 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. 
