232 THE INHABITANTS OF THE SEA. 
Plectognaths, which are distinguished by having the superior 
maxillary bones and the intermaxillaries soldered together so as 
to render the upper jaw immovable, or incapable of projection. 
Among the Plectognaths, we find among others the prickly Globe- 
PorcupinesFish.—(Diodon hystrix.) Globe-Fisn. 
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, Trunk-Fish.—(Ostracion triqueter.) 
(Orthagoriscus Mola.; 
fins, mouth, and a small portion of the gill-opening, capable of 
motion; and the gorgeous Balistze or File-fishes, which owe their 
family-name to the peculiar 
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.—(Bauustes erythropterus.) 
