62 y^RIAL FAUNA. \ 



Vertehrata and Arthropoda stand pre-eminent. In the first 

 we find the lowest class (i.e. fishes) is aquatic and mainly 

 marine ; the amphibians are freshwater and terrestrial. The 

 reptiles still cling to the aquatic life but the majority 

 of birds and mammals are typically terrestrial or aerial. 



In the Arthropoda^ again, the Crustacea are typically 

 aquatic and are in many respects the lowest class, but the 

 Arachnida, and above all the Lisecta^ are large and important 

 terrestrial classes. Other terrestrial animals belong to the 

 MoUusca (Gastropoda)^ Platyhebninthes^ Nematoda and 

 Annelida. With the exception of these three lowest phyla, 

 all show special air-breathing respiratory organs, moisture is 

 supplied to the food by salivary glands, and iron replaces 

 copper in the blood. All are piano-symmetric (with very 

 few exceptions). 



We may distinguish several subsidiary divisions : — 



1. Cursorial (running). I 3. Arboreal (tree-dwelling). 



2. Fossorial (burrowing). | 4. Reptant (creeping). 



3. :^rial Fauna. — This fauna is still more select and 

 smaller in numbers than the last. Nearly all the birds, a 

 few mammals, one or two fishes, some extinct reptiles, and 

 any number of insects make up the group. They are mainly 

 characterised by extremely active bodies, paired " wings '^ 

 as locomotor organs, and highly-developed sense-organs. 



They resort to the terrestrial or aquatic habitat for their 

 reproduction and they have themselves been derived from 

 terrestrial ancestors. (In one or two cases from aquatic.) 



Summarising, we may distinguish in the physical 

 distribution of animals certain habitats which involve special 

 physical conditions and are inhabited by special faunas. 

 Of these we can clearly distinguish — 



Freshwater. 

 Terrestrial. 



There is also evidence for believing that the general 

 trend of evolutional progress, the phylogenetic migration of 

 the animal kingdom, has been from Pelagic to Neritic, from 

 Neritic to the Abysmal and the Freshwater. From the 

 Freshwater it has passed to the Terrestrial and thence to 



