Fig. 217 TREE-FROG. 



270 INTRODUCTION TO ZOOLOGY. 



Tree-frogs (Hylce, Fig. 217). They are described as beautiful 

 and active little animals, not unlike in their colours to those 

 of the trunks and foliage, and furnished at the end of their 

 toes with small cushions or pads, by means of which they can 

 adhere to smooth surfaces. Some of them utter a pleasing 



chirp, which in the cool 

 evenings swells into a 

 kind of concert, the 

 Cicadas and Crickets 

 taking part in the per- 

 formance.* 



The respiration of the 

 Frog is not carried on 

 by the lungs alone, but 

 also by the skin; and 

 in order that the skin 

 may be always kept 

 moist, and in a state fit 

 to perform this important function, the creature is furnished 

 with an internal reservoir of pure water, absorbed and there 

 deposited when fluid is abundant, and given back to the skin 

 when additional moisture is required. There is a peculiarity 

 even in the pulmonary respiration: it cannot be carried on in 

 the Frog by the expansion and contraction of the chest, for 

 it is destitute of ribs. The air is taken into the mouth, and 

 the nostrils and throat being closed, it is forced down into the 

 lungs. As this movement can only be performed when the 

 mouth is shut, the poor creature would perish for want of 

 pulmonary respiration if gagged with the mouth open.f 



The Frog is believed to have been introduced into Ireland 

 in the early part of the last century. The common Toad 

 (Bufo vulgaris) is there unknown, its absence being accounted 

 for, according to popular tradition and song, by the malediction 

 of St. Patrick. The smaller species, the Natter-jack (B. ca- 

 lamita), does not appear, however, to have been banished with 

 the rest of ' ' the varmint, ' ' as it is found in three or four 

 localities in the County Kerry, and at Ross Bay, County Cork. 

 Both Frogs and Toads pass the winter in a state of torpidity. 



* At Rio de Janeiro. Darwin's Journal, p. 34. 



f Bell. Berghaiis and Johnston mention that the common Frog 

 (Rana temper arid) is found on the Pyrenees at an elevation of 7,700 

 feet. 



