CH. Il] REASONS FOR ADOPTING MR SCLATER'S REGIONS. 79 



to believe have been permanent during considerable 

 geological periods. 



(2) They are rich and varied in all the main types of 

 life. 



(3) They possess great individuality ; whether ex- 

 hibited by the possession of numerous peculiar species, 

 genera, or families, or by the entire absence of genera or 

 families which are abundant and wide-spread in some of 

 the adjacent regions. 



Mr Wallace admits that these regions are not quite 

 perfect in all of these requirements, but they are more so 

 than any other arrangement which has been devised. The 

 Nearctic for instance is the poorest and the Neotropical 

 region is the richest ; there is not an absolute equality 

 between any two ; nor could the world be split up so as to 

 attain to that desirable end. It is a matter of the very 

 smallest importance to wrangle over the division which is 

 most natural ; as Mr Wallace says " there is no question 

 of who is right and who is wrong in the naming and 

 grouping of these regions or of determining what are the 

 true primary regions. All proposed regions are from 

 some points of view natural but the whole question of 

 their grouping and nomenclature is one of convenience 

 and utility in relation to the object aimed at." 



It is clear that if our Zoological regions were to be 

 constituted on the evidence afforded by the groups of 

 animals whose range has been briefly sketched in its 

 main outlines on previous pages they would not agree 

 entirely with those of Mr Sclater or with each other. 



The Herpetological regions show a marked difference 



