318 GENERAL ZOOLOGY 



lower forms the body may be covered with bony plates, and 

 the skeleton may be hardly more ossified than in the group 

 which has just been considered. In all teleostomes, however, 

 the gills open beneath a protecting operculum. The order 

 comprises ninety-five per cent of all known fishes. 



FIG. 157. Photograph of Skate 



The garpikes of American waters illustrate one type of 

 body-covering, consisting of bony, enameled, closely set 

 plates, which form a complete coat of armor. The sturgeons 

 (Fig. 158) illustrate another type in which the armor is 

 greatly reduced, the teeth absent, and the animals adapted to 

 bottom-feeding by the development of a beak, and by barbels 

 for feeling for their food in the mud. Sturgeons are found in 



