530 



THE OCEAN WORLD. 



for some time more or less soft, becomes finally hard. The chief cha- 

 racteristic of the order is that the maxillary is firmly attached to the 

 side of the intermaxillary hone which forms the jaw, and the arch of 

 the palate is united to the skull in such a manner as to be motionless. 

 The operculum and rays of the gills are hidden under a thick skin, 

 which leaves externally only a small branchial slit. These fishes 

 have no true ventral fin, and have only vestiges of side fins. 



This order comprehends two natural families characterized by the 

 armature of their jaws. They are the Gymnodonta and the Sdero- 

 dermata. 



Fig. 357. The Globe-fish (Orthagoriscus), aLd Sun-fish (Tetrodon). 



In the family of Gymnodonta the jaws have no apparent teeth, 

 but they are furnished with a species of beak in ivory, which repre- 

 sents them. The Sun-fish, Tetrodon (Fig. 357), belong to the 

 family. 



The Globe- fish are so named from their large head and bony salient 

 jaws, which are each divided in front by a sort of vertical slit in two 

 portions, which simulate two teeth. These four portions of bony jaw, 

 which project beyond the lips, somewhat resemble the hard and dentate 

 jaws, of the turtle. Their anterior part is sometimes prolonged, like the 



