176 FIBST LESSONS IN ZOOLOGY. 



powerful leapers, the legs being muscular, and their toes 

 very long. They can also run and climb. The lower Jaw 

 is usually toothless. In the toad there are no teeth in 

 either jaw ; it swallows its food whole. The lower eyelid can 

 be drawn over the eye and the nostrils can be covered by 

 membranes, while the ears are covered externally by a large 

 tympanic membrane. In the toad the skin, especially near 

 the ear, is rough and warty, containing glands, which pour 

 out an acrid, milky secretion, which may be distasteful to 



Fig. 183.— Skeleton of a frog, a, skull; b, vertebrse: c, sacrum, and e, Its contin- 

 uation (urostyle); /, suprascapula; (i. humerus; h, fore-arm bones; i, wrist- 

 bones (carpals and metacarpals) ; d, ilium ; m, thigh (femur) ; n , leg-bone (ulna) ; 

 o, elongated first pair of ankle-bones (tax'sals); p, q, foot-bones or phalanges. 



birds, and is an irritant poison when applied to the eye- 

 lids. ' 



While most frogs are greedily devoured by herons and 

 other large wading-birds, as well as ducks, geese, and snakes, 

 and while such species are only preserved from extinction 

 by their nocturnal habits and their protective resemblance 

 to the herbage and leaves of trees, there is a little bright 

 red and blue frog iu Mcaragua which hops about in bright 

 daylight. It owes its life to its bad taste, for ducks and 

 fowl will on this account not eat it. 



