LABYRINTHINE APPARATUS OF LABYRINTHIC FISHES. 505 



furrows formed here by the sides of the pouch. Experiments 

 show that water is not detained in sufficient quantities between 

 small plates with such a distance between them. I have 

 tried to fasten together covering glasses in such a manner as 

 to keep their sides parallel, with a distance from 1 to 3 mm. 

 between each, and have found that with a surface of the 

 glasses equal to 324 square mm., and with a distance of 1 mm. 

 between each, the surface of water detained therein was equal 

 to about 80 square mm.; with a distance of 2 mm. the surface 

 of detained water was still less, and with a distance equal to 

 3 mm. the water was accumulated on a surface exceeding a 

 little 0*5 mm. just round the cork that kept the glasses 

 together. The quantity of water between the lamellse was 

 again still smaller if, instead of glasses, cartoon or British 

 paper was used. Consequently the apparatus of Anabas, if 

 applied for the purpose attributed to it by Cuvier, would in 

 any case function imperfectly. 



The apparatus of a Macropodus is still less fit to function in 

 that way. It also consists of three parallel lamellae or plates 

 (see figure 4) which are placed in such a manner as to be 

 quite unable to obtain water. The (first) top plate is so bent 

 that its back part only remains parallel to the middle one; 

 the third one forms a rectangle with it ; the lower part is 

 elongated more towards the pectoral surface of the fish, 

 whereas two top lamellse have grown in the opposite direction 

 (see drawings 4 and 1). 



The labyrinthine apparatus of Osphromenus olfax is so 

 much like the apparatus of Anabas, that the aforesaid can be 

 wholly applied to it. 



But what are, then, properly the functions of the labyrinthine 

 apparatus of the Labyrinthici ? 



A study of the fine microscopic structure of this organ gives 

 us a right to make a supposition that will better explain its 

 functions than the supposition made by the great naturalist. 



The projecting bone of the third segment of the last 

 branchial arch serves as support or basis to the labyrinthine 

 apparatus (see PL XLI, fig. 8, os.). 



