SKELETON OF FEOG. 



151 



through the orifices. Very little room is left for the brain, and, in consequence, the 

 intellectual powers of the Frog are but slender. 



The vertebra are furnished with projections at each side, but the ribs are totally 

 wanting. On account of this deficiency, the process of respiration cannot be maintained 

 as is usual among the better developed beings, but is similar to that which is employed by 

 the tortoises. The needful movements are made not by the sides but by the throat, so 

 that if a quiescent Frog be watched, it appears to be continually gulping something down 

 its throat, as is indeed the case, the material being air, which is thus forced into the 

 beautifully formed lungs. The formation of the pelvis is rather peculiar, and can be 

 comprehended by reference to the illustration. 



The hind-legs are extremely long, and the toes so much lengthened, that in the 

 common English Frog the middle toe occupies about three-fifths of the length of the entire 

 body, and in some species is even more produced. Owing to the peculiar shape of the 

 limbs, the Frog when reposing sits almost upright, and is at once ready for the extra- 

 ordinarily long leaps which it can 

 take when alarmed. The usual 

 mode of progression is by a series 

 of jumps, though of short range, 

 but the creature will often crawl 

 after the fashion of the toad the 

 presence of a snake seeming al- 

 most always to have the effect of 

 causing the change of action. 



The skin of the Frog is very- 

 porous, and is capable of ab- 

 sorbing and exuding water with 

 wonderful rapidity. If a Frog, 

 for example, be kept for some 

 time in a perfectly dry spot, it 

 loses its fine, sleek condition, be- 

 comes thin and apparently ema- 

 ciated, and assumes a very pitiable 

 appearance. But if it be then 

 placed merely on wet blotting 

 paper, its thirsty skin drinks the 

 needful moisture, and it soon be- 

 comes quite plump and fresh. A 

 familiar proof of the extreme 

 porosity of the skin is afforded 

 by the dead Frogs which are often 



found on the high road or dry paths in the middle of summer, and which are dried into 

 a shrivelled, horny mass, which would be shapeless but for the bones of the skeleton 

 around which the skin and muscles contract. 



The whole of these creatures are most tenacious of life, suffering the severest wounds 

 without appearing to be nmch injured at the time, and bearing the extremes of cold and 

 hunger with singular endurance. Heat, however, is always distasteful to the Frog, and 

 when carried to any extreme becomes fatal. In the hot countries, where Frogs of 

 various species exist, they all unite in the one habit of avoiding the hot beams of the sun 

 by hiding in burrows or crevices during the day, and only emerging from their refuge in 

 the night-time, or during rainy weather. Many species even dive below the muddy soil 

 of pools as soon as the water has nearly disappeared, and there remain moist, torpid, and 

 content until the next rains refill their home with the needful waters. 



Most of the Frogs have a power of changing the colour of the skin, which is ofter 

 found to lose its brightest tints and become dark brown or nearly black in a very short 

 space of time. Any sudden alarm will often produce this change, the presence of a snake 

 being an almost unfailing means of effecting this object ; and it is known that the colour 



SKELETON OF FROG. 



