1 66 



BACKBONED ANIMALS. 



NOTE. The eggs of the Chinuzm are deposited in thick, leathery 

 cases, and those of Callorhynchus are remarkable for their mimicry or 

 protective resemblance, resembling the leaf of the fucus or sea-weed to 

 which they are attached. They form a long, depressed ellipse, with a 

 plicated and fringed margin, and, swaying in the current, their true 

 nature would never be suspected. 



Sub-Class II. BRIGHT-SCALED FISHES (Ganoidei). 



General Characteristics. The Ganoids have hard, glis- 

 tening scales, cartilaginous or ossified skeletons, and one 

 pair of gill-openings, protected by opercular bones. 



FIG. 204. Sharp-nosed sturgeon (A. oxyrhynchus). 



Order I. Chondroganoidei. The Sturgeons (Aci- 

 penseridcz). The sturgeons (Fig. 204) have cartilaginous 

 skeletons, the skin being armed with bony bucklers or 

 plates, arranged in longitudinal rows. The mouth is 

 toothless and under the snout, 

 and is adapted for sucking in 

 soft food (Fig. 205). The sharp- 

 nosed sturgeon attains a length 

 of eight feet. It breeds, as do 

 the entire family, in fresh water, 

 the female depositing millions of 

 eggs. The shovel -nosed stur- 

 geon and the curious spoonbill 

 (Polyodon folium) are found in 



the Mississippi. Glue, cement, court-plaster, isinglass, 

 etc., are made from the air-bladders of sturgeons. 



NOTE. The Aci*>enser huso attains a length of twenty-five feet. 

 The fisheries at Ruibinsk, on the Volga, Russia, give employment, ac- 

 cording to Duncan, to one hundred thousand persons, and the fish have 



FIG. 205. The sturgeon's 

 head seen from below, 

 showing the tube -like 

 mouth and the four bar- 

 bels or feelers. 



