281 



CHAPTEE XI. 



CHOEDATA — Contimoed. 

 The Charactbes of Craniotb or Vbbtbbrate Animals. 



The remaining divisions of the Chordata — namely, the Fish 

 (Pisces), Frogs, &o. (Amphibia), Snakes, &o (Keptilia), Birds 



D, 



D 



FiQ. 147 — Diagrammatic Sections of an Invertebrate and Vertebrate. 



D, Dorsum ; v, venter ; H, hicmal or blood system ; Be, body ca-\'i ty ; Bw, body wall ; 

 G, gut ; Nc, nerve chord ; ^e, neural canal ; N, notochord ; P, pericardium. 



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

 or true Vertebrate animals. Although these two great sub- 

 kingdoms, the Invertebrata or Achordata and the Chordata or 



