264 STUDY OF NATURAL HISTORY. 



the humming-birds, the sun-birds, the whole of the 

 typical waders (Grallatores), the Lepidoptera and 

 Hemiptera, the zoophagous Testacea, the suctorial 

 JRadiata, the worms and the leeches. These ex- 

 amples, it will be perceived, are taken almost at 

 random from different classes of the animal king- 

 dom; and clearly show that essential characters, 

 founded on this particular structure, are of primary 

 consequence. 



(182.) We are now to consider the value of 

 distinctions derived from the organs of locomotion, 

 that is, from the feet and wings : these two members 

 being represented in fish and other aquatic animals 

 by fins. Each of these is entitled to a separate 

 consideration. The most perfect developement of 

 foot is found in quadrupeds, and the different modi- 

 fications of structure which it presents are truly 

 surprising : the feet of some are barely sufficient to 

 enable the animal to crawl slowly and irregularly 

 upon the ground; and even this, in the sloths, is 

 obviously accompanied with pain. Some of the 

 Lemurs, also, are equally incapacitated from the 

 ordinary motion of quadrupeds. Yet, place these 

 animals on trees, and they appear to be in their 

 proper element — active, expert, and indefatigable; 

 " they live, and move, and have their being," not 

 by walking but by climbing. But the most accom- 

 plished scalers of trees are the monkeys, whose 

 limbs, in fact, are more perfectly formed for this 

 purpose than those of any quadruped in creation : the 

 agility which these animals display in their native 

 forests is really astonishing, and far exceeds that 

 which they still retain in confinement. What a con- 



