ORDER BATRACHIA. 449 



which then swells. It is heard under the same circumstances 

 as that of the frogs, and especially during rain, and in the 

 middle of the fine nights in summer. Often, during that 

 season, the hylae are to be found assembled on the tops of 

 trees, sending forth in chorus their hoarse and discordant 

 music. 



In Europe, there is but a single species belonging to this 

 genus. It is the tree-frog {rana arhorea, h'mn.). This batra- 

 cian is very common in the southern countries of Europe ; but 

 more rare as we proceed northwards. M. Bosc thinks that 

 he has met with it near Charleston, in North America. It 

 seems to avoid dry situations and mountainous forests. It is 

 only to be found in humid woods, in hedges bordering on 

 marshes, in parks and gardens ornamented with pieces of 

 water. 



Its internal organization, its mode of reproduction, the 

 phenomena relative to its fecundation and eggs, the gi'owth of 

 the tadpole, the metamorphosis, exhibit no difference from 

 the frogs, except that the coupling takes place a little later in 

 the season. 



It appears that it is not until the third or fourth year 

 of its existence that this species is fit for propagation. Un- 

 til this epoch, the male is nearly mute. It also seems that 

 two months' time and more is required for the tadpole to un- 

 dergo its metamorphosis, and come to the perfect state in 

 which it is enabled to leave the water. It has been observed 

 by M. de France that these hylae swallow their skin at each 

 moulting. 



The hyla lateralis has been observed by Catesby and M. 

 Bosc in Carolina. It is said also to have been seen at Suri- 

 nam. It is usually found attached underneath the green 

 leaves of trees, to conceal itself, and lie secure from the birds 

 and serpents, which are among the most dangerous of its 

 enemies. 



VOL. IX. 2 G 



