358 O^ THE RESPIRATION OF FISHES. 



duce, as we shall see presently, a result nearly similar to 

 that I have mentioned in the tortoise. 



Fishes that live There are fishes that lire habitually in mud and sand; 



mudl"^^^^ "^ ^°°^® *" ^^y ^^^^^^ for the species on <*hich they feed, as 

 the lophii, siluri, murenophides, &c. ; others to shelter 

 themselves from the attacks of more voracious fishes, as the 

 ammodytes, callionymi, batrathoides, cotti, &c. In general 

 in all these inhabitants of the mud we find the cavity of the 

 bronchia considerably expanded, in order to receive a 

 larger quantity of water, which is kept as it were in re, 

 rerve : we perceive also, that the radii of the bronchioste, 

 gous membrane are considerably elongated, and the ex- 

 ternal aperture of the bronchiae is very small in prbportion 

 to the extent of the cavity. All these. circumstances are 

 ¥ery naturally explained, when we know these species, 

 like frogs and tortoises, require several successive aspira- 

 tions, to fill with water that kini of bag, in which the 

 bronchias are immersed, and which can be emptied at once, 

 when the fish has no longer need of remaining in ambuscade, 

 or comes into pure water to inspire a fresh portion. 



An additional We find an addition to the common organization in those 



organ in such species of fishes, which in certain peculiar circumstances 



as can hve some ^ ' *^ - 



time out of can leave the water, and remain on land, or in the mud of 



vater. half-dried ponds, for a larger or shorter time. I am not 



speaking here of the false bronchiae, which Mr. Broussonet 

 has very well described under the name of pseudobronchia, 

 and which has since been found in several fishes ; but of a 

 peculiar organ, a vascular expansion analogous to lungs, 

 which lies loose in a cavity appropriated to it, but commu- 

 nicating with that of the common bronchiae, from which it 

 ^receives water. Copsequently this is an accessory organ, 

 similar in its uses to the air-bags observed in the chameleon, 

 and in all birds. It is true we are yet acquainted with few 

 instances of this remarkable arrangement; but I shall 

 point out five, that are very striking. 

 Instances of I shall first mention the cephalopholis scansor of Tran- 



^^^^' quebar, \_perca scandens]^ described by Daldor/ in the 3rd 



volume of the Linnean Transactions. This fish, which is 

 in the Museum of Natural History at Paris, has the faculty 

 of climbing trees by means of the spines^ with which the 



different 



