256 COMPARATIVE ZOOLOGY 



never one limb alone. The clawed animals, like the 

 cat and lion, make use of their feet in securing prey, all 

 four limbs being furnished with curved retractile claws ; 

 but the food is conveyed into the mouth by the move- 

 ment of the head and jaws. Man and the monkeys em- 

 ploy the hand in bringing food to the mouth, and the 

 lips and tongue in taking it into the cavity. The thumb 

 on the human hand is longer and more perfect than 

 that of the apes and monkeys ; but the foot of the latter 

 is also prehensile. 



2. The Mouths of Animals. In the parasites, as the 

 tapeworm, which absorb nourishment through the skin, 

 and insects, as the May fly and botfly, which do all their 

 eating in the larval state, the mouth is either wanting or 

 rudimentary. The amoeba, also, has no mouth proper, 

 its food passing through the firmer outside part of the 

 bit of protoplasm which constitutes its body. Mouth 

 and anus are thus extemporized, the opening closing as 

 soon as the food or excrement has passed through. 



In the infusoria the " mouth " is a round or oval open- 

 ing leading through the cuticle and outer layer of proto- 

 plasm to the interior of the single cell which makes 

 their body. It is usually bordered with cilia, and situ- 

 ated on the side or at one end of the animal (Figs. 9, 1 1). 



An ellipticah or quadrangular orifice, surrounded with 

 tentacles, and leading directly to the stomach, is the 

 ordinary mouth of the polyps and jellyfishes. In those 

 which are fixed, as the actinia, coral, and hydra, the 

 mouth looks upward or downward, according to the 

 position in which the animal is attached (Figs. 17, 34, 

 236); in those which freely move about, as the jellyfish, 

 it is generally underneath, the position of the animal 

 being reversed (Fig. 22). In some, the margin, or lip, 

 is protruded like a proboscis; and in all it is exceed- 

 ingly dilatable. 



