OUR FACE FROM FISH TO MAN 



although belonging to another order of ganoid 

 fishes, bears a striking general resemblance to its 

 Devonian relatives. 



Among these ancient ganoid fishes there are two 

 groups that have claims for the honor of standing 

 nearest to the main line of ascent. The first lot 

 were fierce, predatory, pike-like forms, which had 

 stout fan-shaped paddles, two pairs, corresponding 

 to the fore and hind limbs of land-living verte- 

 brates. To judge from the fact that they had 

 internal nares or nostrils as well as external ones, 

 these ancient lobe-finned ganoids already possessed 

 a lung in addition to gills and were therefore able 

 to breathe atmospheric air directly when the 

 streams and swamps in which they lived tem- 

 porarily became dry. Today this group of lobe- 

 finned or crossopterygian ganoids is represented, 

 if at all, only by two living genera of fishes: the 

 bichir (Polypterus) of the Nile and its elongate 

 relative Calamoichthys. In its mode of embryonic 

 development Polypterus shows resemblances both 

 to the lung-fishes and to the Amphibia. 



The rival claimants for the honor of standing in 



the human line of ascent were the true lung-fishes, 



or Dipnoi. The several survivors of this group at 



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