PRIMABY DIVISIONS AND CLASSES. 



211 



annular portions, called vertebrae; that the apparatus for the 

 circulation is very complete, and that the heart offers at least 

 two distinct reser- 

 voirs; thatthehlood 

 is red; that the limbs 

 are almost always 

 four in number, and 

 never more; finally, 

 that there exist dis- 

 tinct organs lodged 

 in the head for sight, 

 hearing, smell, and 

 taste. We have 

 instanced man and 

 thedogas specimens 



of this type, but we may also include the bird, the reptile, 

 and the fish. 



375. Annulated Animals, or Entomozoaria. In the 

 second primary division of the animal kingdom we find a 

 general mode of conformation quite different from the pre- 

 ceding. The body is still symmetrical and binary, as in the 

 vertebrate animals, but it is composed of a series of parts 

 which repeat each other, so that it may be divided into a 

 considerable number of segments, homologous [or at least 



Fig. 163. Ideal Section of the body of a 

 Lobster or Crawfish.* 



Fig. 164. Centipede Scolopendra. 



analogous, K. K.], and more or less like each other (Fig. 164). 

 The nervous system is moderately developed, and is com- 

 posed of a double series of small medullary centres, called gan- 

 glions, reunited in a longitudinal chain, so as to occupy the 

 greater part of the length of the body (Fig. 162). 



* Ideal section of the body of a lobster or crawfish : e, the stomach, 

 underneath which may be seen the gullet and the mouth ; ?, intestine ; f, 

 the liver ; , the heart ; c, cephalic nervous ganglions situated before and 

 above the gullet ; g, thoracic and abdominal ganglions situated below the 

 alimentary canal. 



p 2 



