SERPENT-HEADS. 



409 



and caudal fins, first one of the former being advanced and then the other. These 

 fishes appear to be monogamous, some breeding in grassy swamps or the edges of 

 tanks, some in wells or stone-margined receptacles for water, and others again in 

 holes in river-banks. The varieties which live in tanks and swamps keep much 

 to the shallow and grassy edges. Amongst the fish which I myself saw exhumed 

 from the mud of a dried-up tank were some Ophiocephali ; they are also recorded 

 by the natives of India as descending with downpours of rain." When living in 

 muddy water they rise to the surface from time to time to take in atmospheric 

 air, and captive examples prevented from doing this have been known to die. 



STRIATED SERPENT-HEAD ( nat. size). 



During the time they are buried in hard mud it must be assumed that these fish 

 become completely torpid and stop the respiratory function. 



THE LABYKINTH-GILLED FISHES, Families ANABANTID^ and LUCIOCEPITALID^. 



In the members of these two families of estuarine and fresh- water fishes, 

 which constitute a sectional group by themselves, the apparatus for enabling 

 them to exist for a considerable time out of the water is carried to a greater 

 degree of complexity than in the last, and takes the form of a laminated accessory 

 gill-like organ, situated in a chamber on each side of the head above the one 

 containing the true gills. In these fishes the body is compressed, oblong, and 

 elevated, with medium-sized ctenoid scales. The eyes are lateral, the gills four 

 in number, the gill-opening rather narrow ; and false gills either rudimentary or 

 wanting. The single dorsal fin, as well as the anal, has a variable number of 

 spines ; and the pelvic fins are thoracic in position. While in some cases the 

 lateral line is interrupted, in others it is altogether wanting ; and the air-bladder 

 may be either present or absent, but when developed it is generally very large, 

 sometimes even extending into the tail. These fishes, which are of comparatively 

 small size, are confined to Southern Asia and South Africa, and are all capable of 

 existing for a longer or shorter period out of their native element, when they 

 oxygenate their blood directly from atmospheric air by means of the accessory 



