HIGHER CHORDATES 



277 



lateral sensory line 



PROTOPTERUS 



cycloid scales 



NEOCERATODUS 



Figure 16.12 General appearance of two of the living lungfishes. {From Malcolm Jollie, Chordaie 

 Morphology, Reinfioid Publisfiing Corp., New York, 1962.) 



paired fins with bony rays, but without basal lobe 

 portion; fresh-water or marine; three superorders, all 

 represented in North America (Figures 16.13, 16.14 

 and 16.15). 



Superorder Chondrostei (Primitive Ray-finned Fishes) 



Diagnosis: North American species: backbone 

 deflected upward into upper lobe of tail; tail fin 

 strongly bilobed, the upper lobe usually larger than 

 the lower; body species without scales or with longi- 



tudinal rows of bony plates; skeleton mostly carti- 

 laginous; fresh-water and marine. 



The primitive ray-finned fishes have an example of 

 the ancestral lunged condition in the living African 

 bichirs. These animals, including about ten species 

 of true bichirs and a so-called reed fish, also display 

 the ancestral covering of thick and shiny bony scales 

 (Figure 16.13). 



The two North American types are the paddlefish, 

 or spoonbill, of the Mississippi and the more widely 

 distributed sturgeons (Figure 16.14). Most of our 



spiracle 



nasal tube. 



POLYPTERUS 



pectoral fin 



CALAMOICHTHYES 



Figure 16.13 The two living genera of African chondrostians, a bichir (Polypterus) and reed f^sh 

 {Chalamoichthyes), Order Polypterini, Superorder Chondrostei. (From Malcolm Jollie, Chordate 

 Morphology, Reinhold Publishing Corp., New York, 1962.) 



