LABYKINTHICI. 



515 



of 'both sides coalescent helovj the isthmius, and scaly ; gills four ; 

 pseudohrancliim ruditnentary or absent. 



rreshwater-fishes of the Cyprinoid division of the Equa- 

 torial zone. They possess the faculty of being able to live 

 for some time out of the water, or in thick or hardened mud, 

 in a still greater degree than the fishes of the preceding 

 family. In the accessory branchial cavity there is lodged a 

 laminated organ whicli evidently has the function of assist- 

 ing in the oxygenisation of the blood. In Anahas it is formed 

 by several exceedingly 

 thin bony laminae, similar 

 in form to the auricle, 

 and concentrically situ- 

 ated one above the other, 

 the innermost being the 

 largest. The degree in 

 which these lamina are 

 developed is dependent 

 on age. In specimens 

 from one inch and a 

 half to two inches and a half long there are only two 

 such lamina;, a third being indicated by a small protuber- 

 ance at the central base of the second or outer laminae. In 

 specimens of from three to four inches in length the third 

 lamina is developed, covering one-half of the second. The 

 edges of all the laminte are straight, not valanced. In speci- 

 mens of from four to five inches a fourth lamina makes its 

 appearance in the basal centre of the third lamina. Tlie 

 other laminae continue to grow in their circumference, and 

 their edges now become undulated and slightly frilled. 

 Cuvier and Valenciennes have examined still larger speci- 

 mens. The figure given by them and reproduced here was 

 taken from a specimen six or seven inches long, and shows 

 the superbranchial organ composed of six lamince. 



9 



Fig. 235. — Superbranchial organ of Anabas. 



