232 



THE INHABITANTS OF THE SEA. 



Plectognaths, which are distinguished by having the superior 

 maxillary bones and the intermaxillari.es soldered together so as 

 to render the upper jaw immovable, or incapable of projection. 

 Among the- Plectognaths, we find among others the prickly Grlobe- 



Porcupme-Fish (Diodon hystnxJ 



Globe-Fish. 



fishes and sea-porcupines ; the curiously-shaped Sun-fishes, all 

 head and no body ; the Ostracions or Trunk-fishes, clothed like 

 the armadillos in a defensive coat of mail, leaving only the tail, 



Short Sun-Fish. 

 lOrthasonscus Mola.. 



fins, mouth, and a small portion of the gill-opening, capable of 

 motion ; and the gorgeous Balistse or File-fishes, which owe their 



family-name to the peculiar fc 

 structure of their first dorsal 

 fin. The first and strongest 

 spine of this organ is studded 

 up the front with numerous 

 small projections, which,under 

 the microscope, look like so 

 many points of- enamel or 

 pearl arising from the surface of the bone and giving it the 

 appearance of a file. The second smaller spine has in the fore 

 part of its base a projection which, when the spines are elevated, 

 locks into a corresponding notch in the posterior base of the 

 first spine, and fixes it like the trigger of a gun-lock ; from 

 which the fish is called in Italy pesce balestra, or the cross-bow 



File-Fish.— (BausteB erythropterus.) 



