THE CLIMBING PERCH. 325 



but without water ; and, if it did not possess some 

 special modification of structure, it would soon die. 



This modification is to be found in a remarkable 

 apparatus, called, in learned language, the " super- 

 branchial organ/' a term which I will explain as 

 simply and briefly as possible. 



It is composed, as too many scientific terms are, 

 of one Latin word and one Greek word. In this case, 

 the combination of the two signifies something that is 

 over the gills. If the respiratory apparatus of any of 

 these fishes be examined, it will be seen to be modified 

 in rather a remarkable manner. The aperture of the 

 gills is small and narrow, so that when the fish is out 

 of the water, there is but little loss of moisture by 

 evaporation. If the side of the head be opened, a 

 supplementary apparatus will be found just above the 

 gills, consisting of a number of very thin plates spring- 

 ing from one of the bony arches which support the 

 gills. Between these plates a considerable amount of 

 water is entangled, and serves to keep the gills moist 

 while the fish is out of the water. 



In fact, there is a remarkable analogy between the 

 stomachs of the camel and the respiratory apparatus of 

 the Climbing Perch. In both cases there are excep- 

 tional conditions which require an exceptional structure. 

 In both cases the creature has to endure occasional 

 deprivation of water ; and in both cases it would die 

 if it did not possess some means of retaining an amount 

 of moisture sufficient to support life while it seeks for 

 fresh supplies of water. 



Now, the camel has, as all naturalists know, a 

 stomach which is specially modified for the retention 



