24 DIVISIONS OF THE BODY. 



29. In most of the animals at pre>ent referred to, the members 

 exist in double pairs, and are distinguished as superior, or thora- 

 cic, and posterior or abdominal, or inferior members, or extrem- 

 ities. Certain animals, such as the whale, have only a single pair ; 

 others, such as serpents, have none at all, and others again have a 

 considerable number ; insects have three pairs of feet, spiders four 

 pairs, crabs and lobsters five pairs, the wood-louse, or palmer 

 seven pairs, and certain worms have as many even as five nun- 

 died pairs 



30. In all these animals, the body is enveloped on all sides in 

 a resisting membrane, endowed with sensibility, which is termed 

 the skin ; it is secured from the inside, and its general form ia 

 deternrrned by a solid frame, composed of a number of bones, 

 called a skeleton, (Frontispiece.) Farther on we shall enumerate 

 these bones, speak of their names and various forms. 



31. The skeleton does not exist with all animals; oysters and 

 snails for example are without it ; and with others again, such as 

 lobsters, the skin acquires an extreme hardness, and answers in 

 place of this bony frame; but with all mammiferous animals, 

 birds, reptiles and fishes, there exists a skeleton, arranged in a 

 manner analogous to that of man. 



32. Between this internal frame and the skin or external en- 

 velope, are found the muscles, which constitute what is commonly 

 called flesh, whose function is to produce, by their contractions, 

 all the motions which the animal performs; between these muscles- 

 are placed the vessels which carry the blood to different points of 

 the body, the nerves which give sensibility, &c. 



Within the head, and in the trunk we find also other parts. 



33. The face presents several cavities, which serve to lodge 

 the organs of sight, of smell, and of taste. 



34. The cranium or skull is a sort of bony box, the interior 

 of which is filled by one of the most important organs of the 



29. In the animals at present referred to, how do the members exist ? 

 How are they distinguished ? Have all animals the same number of mem- 

 bers or limbs ? 



30. What is the skin? How is it secured? What is its form ? What is 

 the skeleton ? 



31. Does every animal possess a skeleton? What animals aie without a 

 skeleton ? Is there any instance where the skin takes its place ? What 

 classes of animals have skeletons ? 



32. What aie muscles ? What is their function ? What are placed between 

 the muscles ? 



33. For what purpose are the several cavities in the face? 



34. What is the cranium or Skull ? What dors it. contain ? Is it lull ? 

 What is the continuation of the brain called ? What is found on each side 

 of the Skull? 



