311 



CHAPTER XI, 



CHOEDATA — Continued. 



The Chabaoters of Craniota or Vertebrate Animals. 



The remaining divisions of the Chordata — namely, the Fish 

 (Pisces), Frogs, &c. (Amphibia), Snakes, &c (Eeptilia), Birds 



D. 



D. 



Fig. ISO. — Diagrammatic Sections of an Invertebrate and Vertebrate. 



D, Dorsum ; v, venter ; //, htemal or blood system ; Be, body cavity ; Bw, body wall ; 

 G, gut ; Nc, nerve choi'd ; JVe, neural canal ; A', notochord ; P, ]>ericaidiuin. 



(Aves), and Quadrupeds (Mammalia) — are known as Craniota 

 or true Vertebrate animals. Although these two great sub- 

 kingdoms, the Invertebrata or Achordata and the Chordata or 



