366 Labyrinthici and Holconti 
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 modi- 
fication for the respiration of atmospheric air, and (2) the gill 
filaments discharging their normal function. If, however, 
the fish is kept in water and prevented from coming to the 
surface to swallow the atmospheric air, the labyrinthiform 
apparatus becomes filled with water which cannot be dis- 
charged, 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 branchiz. 
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.” 
Four families of labyrinth-gilled fishes are recognized by 
Professor Gill; and to these we may append a fifth, which, how- 
ever, lacks the elaborate structures mentioned above and 
which shows other evidences of degeneration. 
The Climbing-perches: Anabantide.—The family of Anaban- 
tide, according to Gill, ‘‘includes those species which have the 
Fic. 303.—The Climbing Perch, Anabas scandens Linneus. Opercle cut away to 
show the gill-labyrinth. 
mouth of moderate size and teeth on the palate (either on the 
vomer alone, or on both the vomer and palatine bones). To 
the family belongs the celebrated climbing-fish. 
“The climbing-fish (Anabas scandens) is especially note- 
worthy for the movability of the sub-operculum. The oper- 
