545 



CLASS II— OSTEICHTHYES OR ACT I N OPTE R YG 1 1 



These are the bony fishes in the ordinary sense of the term. 

 Their characters are in general the opposite of those of the 

 Chondrichthyes. The endoskeleton is bony throughout, but there 

 are no placoid scales ; the gills are produced into long filaments and 



Fig. 426. — Actinopterygii. 



A, The Sturgeon ; B, the Crucian carp ; C, the eel ; D, scales on the skin of a whitine. in surface view 



E, the same in section. 



der., Dermis ; epid., epidermis ; w., mouth ; pc.f., pectoral fins ; />/./., pelvic fins ; sc, scales ; set., bony 



plates or scutes. 



