344 



if it were going to take infree air, but descends again without reaching 

 the surface of the water. 



The organs of respiration of this animal are twofold : — 



1 . Well-organized gills on the inner edge of the branchial arches, 

 as in fishes, and a regular gill-cover with a small oblong aperture ia 

 front of the base of the anterior members (see Owen, Trans. Linn. 

 Soc. xvm. t. 25. f. 3, t. 26. f. 1). 



2. Two well-developed cellular lungs of nearly equal size (see 

 Owen, Trans. Linn. Soc. xviii. t. 25. f. 3, t. 26. f. 1, 2). 



3. The uostrils are close together, situated on the under side of 

 the inner lip, with their internal opening on the side of the mouth 

 between the hpsand the outer edge of the large inner series of teeth ; 

 the passage is short, as a probe is easily passed from the one open- 

 ing to the other, and the inner nostrils are very evident in the Uving 

 animal when it opens its mouth to take in air. 



M. Bischoff observed these interior nnafr^io oi^-^ ;- ..i- - /^ 

 or 7 



1 

 boti 

 peri 

 mos 

 or ii 



T 

 Fro{ 

 perf 

 and 

 air T 

 is ta 

 bytl 

 with 



beinj 

 if th 



of ret,^ o- — ■ •>■ . . v ^- """- 



or less open, the fish either coustantly gulping m the water, then 

 closing the mouth or Ups, and emitting it by the lateral opening ; 

 or the mouth is partially open, and the animal uses its tongue 

 and the hinder internal edge of the lip as a kind of valve, by which 

 the cavity of the mouth is closed and the water is forced to pass 

 through the gills. 



The Lepidosirens appear to take in water by the nostrils, and at 

 the šame time to respire both air as Batrachians and water as fish. 



The generality of the Amphibia, as the Toads, Frogs, and Efts or 

 Salamanders, are organized for aąuatic respiration in their young and 

 lower statė, and for aerial respiration in their adult eondition ; but 

 this animal has both kinds of organs in a statė fit for perfect use at 

 the šame time, and the animal evidently uses them simultaneously. 



It appears to me that the Mud-fish is much more nearly related 

 to the Amphibia than to any fish that I am acąuainted \vith ; at the 

 šame time it evidently forms a particular group in that class. 



