Classijicotion of the Ordfr Ostariophi/i^i. 



19 



The African G;cnns Ihjdrocyon has most of tlio characters 

 of Characinro such as Ahstes^ from which it difl'ers especially 

 in the structure of the mouth. The well-developed maxillary 

 is firmly united by suture to the prremaxilhiry, and the latter 

 is movably articulated with the ethmoid. The jaws are not 

 much produced and the teeth are strong spaced canines ; the 

 mouth can be widely opened, and by pulling down the lower 

 jaw the nj)per can be readily made to move in a vertical 

 plane until the edge forms an angle of 50° with its position 

 when the mouth is closed *. 



Family 2. Gastropelecidae. 



The South-American genus Gastropelecus has usually been 

 placed near Chalci'nus, but I find that whilst the latter is 



Fiff. 1. 



Cleithrum and primary pectoral arch (except radials) of 

 A. Gastropelecus pectorosus and B. Chalcinus trachi/jwmus. 



cl, cleithrum ; cor, hypocoracoid ; sc, hypercoracoid (scapula) ; 

 in, mesocoracoid. 



extremely similar to Brycon in osteological characters, Gastro- 

 pelecus is quite different. Gastropelecus is remarkable for its 



* According- to Boulengei- (Cat. African Freshwater Fishes, i. p. 179) 

 the prsemaxillaries ai-e " slightly movable vertically." 



2* 



