LABYRINTHINE APPARATUS OF LABYRINTHIC FISHES. 503 



the work of Peters, this author tries to prove that the labyrin- 

 thine bones correspond not to the upper pharyngeal bones, 

 which are merely the upper fourth segments of the hinder- 

 most branchial arches, but are strongly developed third seg- 

 ments of those branchial arches. Peters does not say a word 

 about the construction of the soft parts of the labyrinths. 

 Besides these two works I have not met with any other 

 account of this interesting apparatus. 



I have been able to make a detailed analysis of a labyrin- 

 thine apparatus of a Macropodus (Polyacanthus venustus, 

 Cuv.). For my experiments I had little fishes brought up in 

 my aquarium from the roe ejected by a female given to me by 

 our indefatigable practical zoologist, A. S. Meschersky. Be- 

 sides that (thanks to the kind permission of Professor Bogden- 

 off, the Director), I studied a specimen of A nab as scandens, 

 var. macrocephalus and Osphromenus ol fax, from the 

 collections of the Moscow Zoological Museum. 



All these fishes had the labyrinthine apparatus set inside 

 the gill-operculum, and surrounded on all sides by a capsule, or 

 walled with a thin membranous net. Its construction is the 

 same as the lining of the cavity of the mouth ; in it can be 

 distinguished the epithelium of the surface, the connective 

 tissue cutis, and scattered here and there pigmented cells. 

 From the above we have the right to draw the conclusion that 

 the sides or partitions of this capsule are only projecting 

 cutaneous coverings of the inner surface of the gill-operculum. 

 Indeed, if we examine under a moderate power the inner surface 

 of a well-prepared gill-operculum of a Macropodus, we shall 

 see on it a little narrow slit leading to the capsule of the 

 labyrinthine apparatus, and connecting its cavities with the 

 mouth and gill-cavities of the fish. 



The same relation betwixt the gill-cover and the labyrin- 

 thine capsule exists in the other fishes which I have examined, 

 viz. Osphromenus olfax and Anabas scandens. 



The labyrinthine apparatus rises up into the cavity of the 

 capsule from its inner side, which touches the exterior sides 

 of the branchial arches (fig. 2), Notwithstanding Cuvier's 



