and Structure of the J^roteivs Angumus. 7 



be compared to tlie four oars of a boat, floating freely in the 

 water, but attached by leathern loops to the sides: if in this 

 state the boat be urged forward by the winds, the oars are soon 

 forced back by the water and laid alongside the vessel. From 

 not making use of their limbs in thus gliding through the water^ 

 it sometimes happens, that these animals, in the act of changing 

 their direction, roll over, and afterwards right themselves, as 

 soon as they have got on their new course. The same thing 

 occurs to lampreys, which, in gliding along, sometimes roll overt 

 and when they descend to the bottom, if they wish to remain at 

 rest, and preserve a rectilinear position, they are constrained to 

 attach themselves to some solid substance, by making use of their 

 mouth, which adheres on the principle of suction, else, having 

 neither feet nor fins to maintain themselves straight, they are 

 obliged to lie down on their sides. These facts seem to shew 

 that the principal use of the fins in fishes is to maintain the 

 body m equilibrio, as the learned M. Cuvier has observed. 



With respect to the movements of the adult salamander in 

 water, as compared with those of the proteus, the authors ob- 

 serve that he is less agile. This may arise from various causes, 

 but principally from the form of the tail, which is not only of 

 less size, but is less adapted for swimming. The larvse also of 

 the salamander are less agile than the proteus, but in that state 

 they swim with more facility than afterwards. This probably 

 arises from the tail in the larva state being proportionally larger,. 

 and also from the larva possessing a lower specific gravity than 

 the adult animal, except when the latter has recently emerged 

 from his winter torpor. That the larvae have a lower specific 

 gravity than the adult salamanders, is inferred from the fact, 

 that they are able to sustain themselves in water, at whatever 

 height they please, only by moving, from time to time, in a slight 

 degree, their claws and tail. It is beautiful to see them continue 

 thus suspended, and as if balanced, on their four limbs in the 

 water, like a bird librating in the air : and afterwards, by strik- 

 ing the water behind them, and by a slight movement of the 

 tail, transfer themselves from one place to another. 



The authors subjoin a few remarks on the movements of these 

 several animals on land. Salamanders move from place to place 

 only by a simple motion of the limbs. They have neither the 



