38 



SCIENCE, 



[Vol. IV., No. 75. 



noticed, further, that this species and the 

 common garter-snake (Eutaenia sirtalis) are 



HYLA VERSICOLOR (NATURAL SIZE 



the first to re-appear in the spring ; and, of all 

 our serpents, these sleep least profoundly. 



Passing now to the batrachians, my obser- 

 vations upon the hibernation of the turtles 

 applies equally to the frogs and salamanders. 

 The toads and tree-toads, terrestrial and ar- 

 boreal animals, are more sensitive to a low 

 temperature than the frogs and salamanders, 

 and therefore disappear quite promptly after 

 a few frosts in autumn, and are seldom seen 

 again until the weather is uniformly mild. On 

 the other hand, this does not hold with the 

 aquatic batrachians. When the ice begins to 

 form along the edges of the ponds, and hoar- 

 frost has wilted the grass, frogs and salaman- 

 ders withdraw to the deeper and warmer 

 waters, — the former to the bottoms of ponds 

 and deep ditches ; the latter to the uniform 

 temperature of the springs, and, its adjacent 

 mud. They do not, at this time, enter direct- 

 ly into a torpid condition. The}' appear, rather, 

 to be sleeping lightly, and, when disturbed, 

 respond by hopping or running off, as the case 

 may be. Of course, the warm spots about 

 bubbling springs soon become crowded, and 

 hibernation proper is the only alternative ; but 

 those that can retain their positions in such 

 springs quietly remain from autumn until 



spring, sleeping, it may be, but never becoming 

 torpid. During the winter I have found all of 

 our frogs, and three species of salamanders, 

 congregated in a hogshead sunk in the ground 

 to collect the waters of a spring. Here I 

 have watched them closely during the winter 

 months ; and the only variation from their ordi- 

 nary habits of the rest of the year was, that 

 they kept close to the bottom of the hogshead, 

 and seldom voluntarily moved about. All their 

 functions were, of course, very sluggish ; and 

 life was sustained by skin respiration, as with 

 the turtles under like circumstances. 



It is scarcely necessary to pursue this sub- 

 ject further. What has already been said of 

 the aquatic reptiles and batrachians is appli- 

 cable to fishes. To a certain extent, these hi- 

 bernate in the true sense of the term ; but it 

 is the exception rather than the rule. The 

 first evidence of a change is seen in the with- 

 drawal from their usual haunts as the water 

 becomes chilled ; but, if we follow this move- 

 ment, it will be found to be a change from 

 shallow to deep waters ; and, unless the cold is 

 very intense, a further change from deep water 

 to mud is not adopted. A remarkable feature 

 of the hibernation of fishes consists in the fact, 

 that, while many individuals of a given species 



RANA STLVATICA (NATURAL SIZE). 



may sometimes be found lying in the mud in a 

 torpid condition, others of the same species, 



