BATRACHIA. 343 



folds on the dorsal regions. It li:is a vory wide goot^raphical distril)ution, extending 

 from the northeastern United States as far as Guateniahi. It presents two well-marked 

 varieties. The true li. halecina is found along the Atlantic seaboard, in the swamps 

 on the borders of the rivers and estuaries. It is of a dark olive color, and has small 

 round brown spots, not light bordered. Its muzzle is more acute. The other variety, 

 herlandieri, is found inland in the United States and extends to Central America. It 

 reaches a larger size, and has a more obtuse snout, and is a bright green above with 

 hirger light-bordered spots. Rana 2)(ilnstris is allied to li. halecina. It is confined 

 to the eastern United States, and extends its wanderings further from water and 

 higher in the mountains than that species. It is of a light brown, and has two rows 

 of large, dark-brown, sub(juadrate spots on the back between the dermal folds of the 

 sides. It has no dermal sacs on the sides of the throat, which are such a marked 

 feature in the H. halecina. The common green-frog of cold springs is the Rana 

 clamata. It is distinguished by the enormous size of its ear-drum, the two dermal 

 ridges one on each side of the back, and by the rather narrow palmation of the hind 

 foot. In tlie bull-frog, R. catesbiana, the ear-drum is not so large, there are no dermal 

 folds on the b;ick, and the foot has a wider welj. It jirefers muddy banks and the 

 edges of mill-dams and lakes as its abode. 



The voices of the Ranas are not as musical or varied as those of the Hylida;. Th(! 

 R. sylvatica is the most silent species. The voice of the R. j^alustris is a low^, 

 strained, prolonged croak, as though woven goods were giving way. In the sjiring 

 the swamps resound with the ' chock, chock ' of the Ra^ia halecina, which, while not 

 very loud in each individual, when performed b}' a chorus of thousands, creates a 

 deafening din. The more solitary R. clamata k n&naWy heard to utter a 'chung' 

 to a small audience in a small spring. The sonorous roar of the Rana catesbiana is 

 well known to every one who dwells in the country near a mill-dam. Several of 

 these animals will awaken the silence of a hot summer evening with notes calculated 

 to disturb the repose of the superstitious. The comparison with the voice of a bull 

 is not very inaccurate. 



The North American species of Rana dejjosit their eggs in large more or less 

 globular masses attached to sticks, plants, etc., in the water. Some of the arboreal 

 species of Ranidfe adopt other modes of securing their reproduction. The Chtro- 

 ■mantis ffiii7ieensis of West Africa deposits its eggs in albuminous masses in bunches 

 of leaves of trees, to which they readily adhere. During the dry season these 

 masses become quite hard, but on the advent of the rains they become soft, and fall 

 to the ground below. As the mother frog is careful to place the eggs in leaves which 

 are suspended over a watercourse, they soon reach tiie ])niper elenieiit for their 

 development. 



The tadpoles of frogs are very voracious, and feed on flesh of such animals, living 

 or dead, as they can masticate with their feelile horny jaws. They are most excellent 

 preparateurs of skeletons, and have furnished the most delicate specimens in jierfect 

 preservation, as was long ago demonstrated by Professor Baird. 



In the dry regions of South Africa are several species of Rana which live in holes 

 in the ground, only issuing after rains. Such species have a shovel on the hind foot, 

 like the species of Pelobatidae, but this character shows so many stages of develop- 

 ment in the different species that they cannot be separated from the genus Rana. 

 One of them, the Rana adspersa, reaches a large size. In Central and South Amer- 

 ica there is a genus allied to Rana, but which differs from it in ha\iug the ethmoid 



