282 DR. F. DAY ON INDIAN FRESHWATER FISHES. [May 14, 



at its edge ; the first and fourth arches have not even the rudiment 

 of a gill. The branchial function is transferred to a receptacle on 

 each side of the head above the branchial arches, covered by the 

 upper part of the opercular membrane ; these receptacles have a 

 cellular and highly vascular internal surface ; the cavity communi- 

 cates with the mouth by an opening between the hyoid and the 

 first branchial arch, and receives its blood from the terminal bifur- 

 cation of the branchial artery, and also from the different vessels of 

 the rudimentary gills. Those from the supplemental lung-like 

 vascular sacs are collected into two trunks, which unite with the 

 posterior unbranched branchial arteries to form the aorta. Thus 

 about one-half of the volume of the blood transmitted from the 

 heart is conveyed to the aorta without being exposed to the action 

 of the air." 



Those who have seen these fish captured will scarcely admit 

 their being usually sluggish. They lie about the sides of ponds in 

 the grass, and are taken by means of baskets which the natives 

 thrust down over them, when they can get near enough ; but before 

 this is accomplished there is almost invariably an exciting chase, as 

 they are very active in their movements. 



Much of the great tenacity of life for which many of the Indian 

 freshwater fishes are famed is, no doubt, owing to their capability of 

 respiring atmospheric air. As an instance of this may be adduced the 

 Aiiabas scandens, which the fishermen in Calcutta are known to 

 keep four or five days in earthen pots without water, using daily 

 what they require, the fish being as well and lively as when caught. 

 In fact the Calcutta market appears to be chiefly supplied with 

 these fishes from extensive marshes in the Yasur district, and about 

 150 miles distant, whence boat-loads are brought and kept alive 

 without water until sold*. In experiments made with these 

 fish at Cochin, I found that they would live without moisture for 

 about 24 or 26 hours. In India the majority of inland Acantho- 

 pterygians are compound breathers — as, for example, the whole of 

 the hollow-headed fishes, as well as many Siluroids and some of the 

 Loaches. This method of respiration appears to be a wise provision 

 of nature, to enable the fish, during periodic dry seasons, to mi- 

 grate from pond to pond in search of water in which their natural 

 food still exists. 



The possession of the means necessary for locomotion on land, 

 combined with those for aerial respiration, frequently leads to their 

 sudden appearance in unexpected places, and has given rise to nume- 

 rous arguments and theories — amongst them spontaneous generation, 

 vivification of buried ova, migration, falling from the clouds, &c. 



Many instances of the migration of fishes by land, from one piece 

 of water to another, have been recorded. On the commencement of 

 the rains in the east, the fish become very excited and disturbed, 

 ascending small streams, &c., and, apparently dissatisfied with the 

 waters they inhabit, restlessly seeking other localities. This may 

 be due to the same instinct which causes the migration of marine 

 * Hamilton Buphanan, 'Fishes of the Ganges,' p. 99. 



