654 FISHES. 



mosaic. Head scalelcss ; its integuments nearly entirely replaced 

 hy hone ; lateral line composed of wide openings of the mucus- 

 duct. Margin of the upper javj formed hy the intermaxillaries 

 mesially, and hy the maxillaries laterally. The dorsal fin 

 helongs to the caudal portion of the vertebral column, is opp)osite 

 and very similar to the anal fin; both approximate to the 

 rounded caudal (ivith which they are abnormally confluent). 

 Gill-openings wide ; pseudobranchice none ; air-bladder simple 

 or cellular. Stomach without coecal sac ; pyloric appendages 

 ttvo. 



Large freshwater-fishes of the tropics, whose singular 

 geographical distribution has been noticed above (p. 223), 



OsTEOGLOSSUM. — Cleft of the mouth very wide, oblique, with 

 the lower jaw prominent. A pair of barbels at the lower jaw. 

 Abdomen trenchant. Bands of rasp-like teeth on the vomer, 

 palatine and pterygoid bones, on the tongue and hyoid. Pectoral 

 fins elongate. 



0. hicirrhosum from Brazil and Guyana, 0. formosum from 

 Borneo and Sumatra, 0. Icichardti from Queensland. 



Arapaima. — Cleft of the mouth wide, with the lower jaw 

 prominent ; barbels none. Abdomen rounded. Jaws with an 

 outer series of small conical teeth ; broad bands of rasp-like teeth 

 on the vomer, palatines, pterygoids, sphenoid, os linguale, and 

 hyoid. Pectoral fins of moderate length. 



'''"^""'";;^:>.., — 



^•-r"^'""" "^ 



Fig. 299. — Arapaima gigas. 



The largest freshwater Teleostean known, exceeding a 

 length of 15 feet and a weight of 400 pounds. It is common 

 in the large rivers of Brazil and the Guyanas, and esteemed as 

 an article of food. "When salted it is exported in large 

 quantities from the inland fisheries to the seaports. 



