THE FROG. 123 



angle, gives rise to the strange appearance of that 

 part of the back of a frog which in the skeleton looks 

 as if it had been broken. At the same time the 

 spinal cavity (as in the tadpole) is obliterated, and the 

 spinal marrow, which the tadpole stage had passed 

 through, is withdrawn." 



The anatomy of the frog is simple ; the ribs are 

 only small, detached bones, or rather cartilages, affixed 

 to the extremities of the transverse processes of some 

 of the vertebrae. The bones of the arms and legs 

 resemble those of the higher mammalia. There are 

 five toes on the hind foot, and sometimes the rudi- 

 ments of a sixth. The fore foot has only four toes, 

 without claws. The hind feet are adapted for striking 

 the water backward in swimming; while this formation 

 causes an awkwardness in walking on land, it greatly 

 facilitates the long leaps which are characteristic of it. 



The tongue of the frog is greatly used by it for 

 catching the insects which are its prey. On the 

 tongue is a viscid secretion which fixes small objects 

 when once they touch it, thus greatly helping the 

 animal in feeding. The frog hybernates in the mud 

 of the pond or stream it frequents during the cold 

 months, and in spring emerges to commence the 

 office of propagation. The frog is extremely useful in 

 the garden in summer, devouring quantities of slugs 

 and the larger insects, which are injurious to vege- 

 tation. The extraordinary and sudden appearance of 

 frogs and toads in places where they had not been 

 known to be present is among those wonders which 

 have not hitherto been satisfactorily accounted for. 

 Frogs can be tamed, and have been known to frequent 



