Labyrinthici and Holconoti 



37 1 



the rivers of southern China and India, crossing to Formosa and 

 to Africa. They are extremely tenacious of life, and are carried 

 alive by the Chinese to San Francisco and to Hawaii, where 

 they are now naturalized, being known as "China-fishes." 



FIG. 304. Channa formosana Jordan & Evermann. Streams of Formosa. 



These fishes have no special organ for holding water on the 

 gills, but the gill space may be partly closed by a membrane. 

 According to Dr. Giinther, these fishes are "able to survive 

 drought living in semi-fluid mud or lying in a torpid state 

 below the hard-baked crusts of the bottom of a tank from 

 which every drop of water has disappeared. Respiration is 



FIG. 305. Snake-headed China-fish, Ophicephalus barca. India. (After Day.) 



probably entirely suspended during the state of torpidity, but 

 whilst the mud is still soft enough to allow them to come to the 

 surface, they rise at intervals to take in a quantity of air, by 

 means of which their blood is oxygenized. This habit has been 

 observed in some species to continue also to the period of the 

 year in which the fish lives in normal water, and individuals 

 which are kept in a basin and prevented from coming to the 

 surface and renewing the air for respiratory purposes are suffo- 

 cated. The particular manner in which the accessory branchial 

 cavity participates in respiratory functions is not known. It 

 is a simple cavity, without an accessory branchial organ, the 



