BIED.S. 403 



tlieir upper shell very high and convex ; their limbs are short and 

 pillar-like, appearing as if cut off; they are terminated, however, 

 by liorny hoof-like claws. The Land Tortoises live exclusively on 

 vegetables, such as leaves and fruits, do not seek the water, are 

 heavy and slow in their movements, and burrow in the earth in cold 

 weather. They are remarkable for their extreme longevity. In the 

 tropics there are species of great size (as the Galapagos Tortoise, re- 

 presented in our figure) ; some, indeed, are so heavy tliat it requires 

 six or eight men to lift them from the ground ; one of these will afford 

 two hundred pounds of excellent meat. 



CHAPTER XXYI. 



Birds (Aves). 



No department of Nature is left unfm-nished with 

 appropriate inhabitants. The inconspicuous an-, and 

 those tracts of seeming space, too elevated for human 

 ken, are traversed by multitudes of feathered beings, 

 whose buoyancy and beauty are alike the objects 

 of our admiration. The pointed beak, the gently 

 swelling shoulder, the expansive wings, the taper- 

 ing tail, the light and bony feet of birds, are all 

 wisely calculated to assist and accelerate their pas- 

 sage through the thin and yielding element. Their 

 bodies are covered with a soft and delicate plumage, 

 so disposed as to protect them from the chilly at- 

 mosphere througli which they pass. Their wings are 

 made of the liglitest materials, and yet the force 

 with which tliey strike the air is so great as to pro- 

 pel their bodies forward with astonishing velocity, 

 whilst the tail serves the purpose of a rudder to 

 direct their flight. Nor is their internal structure 

 less admirably adapted to their mode of life. The 

 frame-work of their bodies is light and thin, and 

 their muscles equally remarkable for energy and 

 strength. Their blood is hot; and, as it courses 

 through their bodies, imparts intense vitality to 

 every quivering fibre. Their movements are conse- 

 quently rapid and energetic. The Falcon cleaves 



