242 LOWER VERTEBRATES. 



surface, in which air is retained for the purpose of respiration. " It seems probable 

 that the air, after having been supplied for aerial respiration, is ejected by the mouth, 

 and not swallowed to be discharged per anum." In fine, the two respiratory factors 

 of the branchial apparatus have independent functions, (1) the labyrinthiform, or 

 branchihyal portion, being a special modification for the respiration of atmosplieric air, 

 and (2) the gill filaments discharging their normal function. If, however, the fish is 

 kept in the water, and prevented from coming to the surface to swallow the atmos- 

 pheric air, the labyrinthiform apparatus becomes filled with water which cannot be 

 discharged, owing to its almost non-contractile powers. There is thus no means of 

 emptying it, and the water probably becomes carbonized and unfit for oxygenizing the 

 blood, so that the whole of the respiration is thus thrown on the branchiae. This will 

 account for the fact that when the fish is in a state of quiescence it lives much longer 

 than when excited, whilst the sluggishness sometimes evinced may be due to poisoned 

 or carbonized blood. Figures of the labyrinthiform apparatus of three genera 

 (Anabas, Macropodus, and Osphromenus), here given, will convey some idea of its 

 relations and modifications. The fishes with labyrinthiform pharyngeals have been 

 generally combined in one family; but some authors recognize three, the Anabantidse, 

 Osphromenidae, and Helostomidag. 



The Anabantid^ include those species which have the mouth of moderate size 



Fig. 137. — Gill labyrintlis of Anabas^ Macropodus, and Osphromenus. 



and teeth on the palate (either on the vomer alone, or on both the vomer and palar 

 tine bones). To the family belongs the celebrated climbing-fish. 



The climbing-fish {Anabas scandens) is especially noteworthy for the movability 

 of the sub-operculum. The operculum is serrated. The color is reddish olive, with 

 a blackish spot at the base of the caudal fin ; the head, below the level of the eye, 

 grayish, but relieved by an olive band running from the angle of the mouth to the 

 angle of the pre-operculum, and with a black spot on the membrane behind the hinder- 

 most spines of the operculum. 



The climbing-fish was first made known in a memoir, j)rinted in 1797, by Daldorf, 

 a lieutenant in the service of the Danish East India Company at Tranquebar. Dal- 

 dorf called it Perca scandens, and nffirmed that he himself had taken one of these 

 fishes, clinging by the spine of its operculum in a slit in the bark of a palm {Borassus 

 flabelliformis) which grew near a pond. He also described its mode of progi"ession ; 

 and his observations were substantially repeated by the Rev. Mr. John, a missionary 

 resident in the same country. His positive evidence was, however, called into ques- 

 tion by those who doubted on account of hypothetical considerations. Even in 

 popular works, not generally prone to even a judicious skepticism, the accounts were 



