3oo 



POLYPTERINI 



Actinopterygii : the formation of the scales, the skeleton of 

 the paired fins, the presence of double dorsal nostrils, the otolith. 

 Excepting for the ventral opening of a bilobed air-bladder, the 

 viscera also resemble those of the lower Actinopterygii; the 

 structure of the brain, heart, and alimentary canal supports this 

 view. 



These facts would hardly justify us in placing the Polypterini 

 among the known Actinopterygii ; but they necessitate the 



y-. 



brm. 



FIG. 273. 



Polypterus lapradii, Stdr. Ventral view of head, h, barbel ; br.m, branchiostegal membrane ; 

 d, clavicle; /, pectoral tin; g, paired .gular plate; m, intergular membrane : op, opercular 

 region. 



separation of the Order from the fossil forms generally associated 

 with it. 



The peculiar subdivision of the dorsal fin is the most distinctive 

 newly acquired character of the Polypterini; presumably the 

 finlets have been derived from a continuous dorsal fin, and this 

 alone is a serious difficulty in the way of deriving these fish from 

 any known extinct forms, except perhaps Tarrasius. A more 

 detailed knowledge of this interesting fossil genus is greatly 

 needed (p. 283). 



Family POLYPTERIDAE. Polypterus, Geoffr. (Fig. 274); Calamoichthys, 

 Smith (Fig. 275); Equatorial Africa. 



