192 BACKBONED ANIMALS. 
stoma, an allied form of the Indian Ocean, the mother carries her eggs 
in a pouch formed by the ventral fins, they being held in place by long 
filaments extending from its sides. 
Fic. 234.—Sea-horse (Phyllopteryx eques), that is protected by its resem- 
blance to sea-weed. 
Order VIII. Plectognathi. General Characteristics. 
—In these fishes the scales are often modified into spines 
or plates. The ventral fins are generally absent. 
File-Fishes (Ba/istide).—The file-fishes are remark- 
ably deep and thin, and are often protected by plates 
or spines re- 
sembling those 
of the Ganoids. 
Allied are the 
trunk- fishes 
(Fig. 235) (Os- 
Fic. 235.—Trunk-fish (Ostracton Yalei). tracionid@), that 
are inclosed in 
a box or armor composed of bony plates or scales; the 
tail, mouth, and fins being the only parts movable. 
