380 FISHES 



The other members of the family Anabantidae are also fresh- 

 water fishes, some occurring in estuaries but none in the sea. 

 They are found in India, Burma and the Malay Peninsula, and 

 also in Africa. 



The Ophiocephalidae or serpent-heads are related to the 

 Anabantidae, and have a similar distribution, but more restricted 

 in Africa, where they occur only in the west central region. 

 They also possess an air-breathing organ, but of a much 

 simpler structure. It is in fact merely a cavity on each side 

 in front of the gills and communicating with the gill-cavity: 

 the membrane lining the cavity is full of blood-vessels and is 

 thickened and folded, but there are no bony plates connected 

 with the gill-arches. There are only two genera, OpJiiocephahis 

 and Chauna, the latter without pelvic fins. They are found 

 both in rivers, " tanks," and swamps, and are able to exist for 

 considerable periods out of water and to travel over land : they 

 also remain torpid or " aestivate " in the mud of dried-up ponds 

 in the hot season. They are said by the natives to descend 

 with downpours of rain, which is not impossible if they are 

 taken up with the dried mud by violent whirlwinds. When 

 living in muddy water they rise to the surface at intervals to 

 obtain air. 



The Osphromenidae, although placed by Boulenger in the 

 Spiny-finned Sub-Order (Acanthopterygii) while the Anaban- 

 tidae are considered to belong to the Percesoces, have consider- 

 able resemblance to the climbing perches. Like the latter 

 they are fresh-water fishes of south-eastern Asia, and Africa. 

 The Paradise-fish, Macropodus viridi-auratus, is a domesticated 

 variety of the Chinese Polyacanthiis, belonging to this family. 

 Most if not all these fishes have labyrinthine organs like those 

 of the climbing perch. 



In the cat-fishes, Clarias and Heterobranchus, the air-breath- 

 ing organ has the form of much-branched highly vascular out- 

 growths of the dorsal ends of one or two branchial arches, 

 enclosed within a posterior and dorsal chamber opening out of 

 the gill-cavity. Clarias and Heterobranchus are again fishes of 

 the Asiatic and African regions. Clarias has an elongated eel- 

 like shape, and in Senegambia " aestivates " in burrows from 

 which it emerges at night to crawl about for food. 



Saccobranckus is another cat-fish of India and eastern Asia 



