c!i.\rn:i; vim. 



Branch Vlll. — Vertebrata (Back-boned Am 



General Characters of Vertebrates. — We ha 1 

 that must oJ the foreg ' animals have tli'' body 



protected by a crusl or shell, enclosing the muscles ami 

 other interna] organs; bul now we come to animals which 

 have an internal bony support or skeleton. T 

 consists of a backbone (Fig. Ill) with bones formii 

 skull ami a series of bones supporting the limbs. Fishes, 

 reptiles, birds, ami mammals or beasts, are familiar exam- 

 pies of vertebrates, while man himself rtebrate. \ 

 tebrates in general have bodies which are symmetrical, 

 the two sides repeal each other; they nave a brain-box or 

 skull containing the brain and tne mouth and pharynx, 

 with two eyes, two ears, and usually two nasal openn 

 To the trunk are attached two pairs of limbs; the tore- 

 arms in man corresponding to the fore legs <>f the I 

 dog. 



Now if we cut a fish ill two. and closely examine the 

 tion, we shall notice thai above the backbone is a little cav- 

 ity containing the nervous cord, and below a much lai 

 cavity containing the vii . heart, Iiv< . roach or 



intestine. Thus there are two cavities, the nervous cue 

 above, and the visceral cue beJow the backbone 175, 



176), In this respect the backboned animal- differ from 

 the backboneless or invertebrate animals, in which there is 

 hut cue body-cavity, with the nervous system situate; 



the thn»r of this ca\ it v. 



Vertebrates have a true heart, with one, generally t 

 auricles, and one or two ventricles, and, besides arteries and 



