6 MANUAL OF NATUKAL HISTOKY. 



Y.—SUB-KHSTGDOM. ACRITE ANIMALS. 



Acrita, Macleay. Cryptoneura (part) Rudolphi. Cy- 

 cloneura (part), Grant Oozoa, Cams. Protozoa, 

 Oken. 



1 Class Poly gastric- Animalcules (Folygastrica, Infusoria) 



2 „ Foraminifers (Foraminif era) 



3 „ Sponges (Porifera, Amorphozoa) 



SUB-KINGDOM OF VERTEBRATES. 



The vertebrate animals constitute the first great 

 division of the Animal Kingdom, and embrace the 

 highest and most intelligent forms of living crea- 

 tures, ascending from fishes, and finally arriving at 

 man himself. The members composing this import- 

 ant group are very numerous, and are formed to 

 inhabit the air, the earth, and the waters, different 

 individuals being adapted for each element by 

 their external configuration and internal structure. 

 Among them are to be found the largest and most 

 bulky of living forms, as the whale and elephant 

 among mammals, the ostrich among birds, the rep- 

 tilian crocodile, and the basking-shark — the giant of 

 the finny tribes. In them the nervous centres are 

 more specially allocated and protected by being 

 placed in a bony canal ; and the organs of special 

 sense are most perfectly developed. The expansion 

 of nervous matter forming the brain first commences 

 in them, at first small and unimportant, but gradu- 

 ally increasing in size and volume until it finally 



