FRESH-WATER FISHES OF SIAM, OR THAILAND 449 



a small proportion of the total respiratory surface, and the major part of 

 respiration is carried on by means of a special structure occupying a cavity 

 over the gills and consisting of a series of thin, concentrically arranged bony 

 plates covered by a vascular mucous membrane, which enables the fish to absorb 

 atmospheric oxs'gen. Some writers have apparently failed to appreciate the 

 exact role of the accessory branchial organ in Anabas. Thus, Dr. Francis Day, 

 who spent many years in India and Burma and published a monumental work 

 on the fishes of those countries, stated that the "hollow supei'branchial 

 oi'gan * * * enables the climbing perch to retain water for a considerable 

 time, so that it can moisten its gills and live whilst out of its native element." 

 This enables the fish to breathe atmospheric air when the gills cannot be used. 

 The gills function only when the fish is submerged ; the superbranchial orgati 

 functions only when the fish is out of the water. 



In the Dravidian language of Ceylon and India and in some Malayan dialects 

 the name for Anabas means a tree climber, but the tree-climbing powers of the 

 fish have been viewed with doubt or altogether denied by some of the leading 

 ichthyologists of India. There is no reason why Anabas should climb trees as a 

 regular habit, and in my rather extensive acquaintance with the fish in India, 

 Burma, Ceylon, Siam, French Indo-China, Malaya, the Philippines, and some 

 of the ludo-Australian islands I have never known one to climb a tree or to be 

 found in a tree except at its base. But from what I know of the out-of-water 

 movements of this fish I would have no difficulty or hesitation in accepting 

 Daldorff's statement. A Palmyra palm, with its rough bark and its fronds 

 beginning near the ground, would be no more formidable for an Anabas to ascend 

 than would be the vertical side of a wicker basket. For a fish that for weeks or 

 months may have been suffering from a deficiency of water, a stream of rain 

 water flowing down an inclined palm trunk would have strong appeal. 



The climbing powers of Anabas are exercised chiefly in leaving its home in a 

 pond, swamp, or canal and seeking other waters that may afford better living 

 conditions. In making this change of quarters the fish may have to travel on 

 dry land, and it is this habit that is characteristic and well known to oriental 

 people. In Siam, I not infrequently came upon an Anabas, usually at night, 

 crossing a dusty road or traversing a dry lawn or field. It was easy to discover 

 the water that a fish was leaving but it was not always possible to determine the 

 particular water to which it was heading. In some cases the body of water to 

 which the fish was obviously bound did nor seem to the human observer to be 

 more attractive than the water that had been left. The banks of drying canals 

 and ponds, up which the fish has to climb, may be high and steep, and skill and 

 patience may be required to negotiate them ; but on arriving at a new body of 

 water the fish may exercise much less care in descending, and I occasionally saw 

 one, apparently deliberately, roll or fall down a steep bank and go into the water 

 with a splash. 



As would be expected in a fish that regularly leaves the water and travels 

 overland, Anabas displays no conspicuous color that might attract attention. 

 The adult fish is of a uniform dark brown while the young is light brown, with 

 a few blackish transverse stripes. 



The walking powers of Anabas seem to be exercised only when it is in quest 

 of a new aquatic environment, and there appear to be no observations indicating 

 that the fish feeds regularly when out of the water, although it may conceivably 

 seize insects or worms that happen to be in its tei-restrial path. 



The walking movements lack the grace and ease of those of a lizard and some 

 of the gobies, such as the mudskipper (Periophthalmus) . The gait is jerky but 

 comparatively fast, and the efforts are usually persistent, so that a fish may 

 travel a considerable distance in a short time. I have a note on the actually 



