CHAP. XXI 



MALACOPTERYGII 



557 



glossohyal toothed ; maiidibular barbels ; branchiostegal rays 

 15 to 17; body compressed, with trenchant abdomen; coracoids 

 forming a ventral keel ; dorsal fin short ; ventral fins nearly 

 equally distant from end of snout and caudal fin ; vertebrae 

 29 to 31 + 30; air-bladder not cellular. One species from the 

 northern parts of Australia, and one from Sumatra. Banka, and 

 Borneo. 



Osteoglossum. Mouth large ; vorner, palatines, pterygoids, and 

 glossohyal toothed; mandibular barbels; branchiostegal rays 10 ; 

 body compressed, with trenchant abdomen ; coracoids forming a 

 ventral keel ; dorsal fin long ; ventral fins nearly twice as far 

 from the caudal as from the end of the snout ; vertebrae 28 + 59 ; 

 air-bladder not cellular. South America (Guianas, Brazil). 



Arapaima. Mouth rather large ; vomer, palatines, ptery- 

 goids, and glossohyal toothed ; branchiostegal rays 1 6 ; belly 

 rounded ; dorsal fin rather long ; ventral fins equidistant from 

 head and caudal fin ; vertebrae 36 to 38 + 41 to 42; air-bladder 

 cellular. South America (Guianas, Brazil). 



Heterotis. Mouth moderate ; branchiostegal rays 7 ; belly 

 rounded ; dorsal fin rather long; ventral fins nearer end of snout 

 than caudal fin; vertebrae 27 + 42 to 43; air-bladder cellular ; 

 fourth branchial arch with an accessory breathing-organ. Africa 

 (Nile, Senegal, Gambia, Niger). 



Dapedoglossus, from the Eocene of Wyoming, appears to be 

 nearest to Scleropages, and Brychaetus, from the Eocene (London 

 Clay) of Sheppey, Kent, to Arapaima, so far as the state of pre- 

 servation of these fossils enables us to form an opinion. 



Dr. Giinther has directed attention to the remarkable coin- 



FIG. 336. Distribution of the Osteoglossids. 



