39S 
ZOO-GEOGRAPHICAL REGIONS. 
or driving- liefore tlieiii tlieir relatively weaker predecessors or isolating 
them within the limits of undesirable districts. 
Although, therefore, the conclusions arrived at are based chieHy 
upon the material afforded by this important grou]), yet they will be 
found to be borne out Ity more extended and deeper study and will 
also be broadly applicable to other organisms. 
The Ai’STRAlasian region embraces Australia, the large eipiatorial 
islands adjacent thereto, Xew Zealand and the islands of Polynesia, 
and is the most primitive zoological region, possessing only the 
simj)lest and weakest organisms, whether of maidvind or other 
creatures. It is characterized hy the })resence of Endodonta and 
other of the most lowly constituted forms of life, the morphologicall}" 
higher groujis not yet having spread so far. 
The Neotropical region, which embraces South America and the 
West Indian Islands, is almost ecpially primitive and weak, possessing 
only ancient and .simple forms of life. It pos.se.sses, towards its southern 
extremity, the haijlogonous group Ampliido.rit, and the protogonous 
genus Pidipjiivut'm, which attest the ancient character of its mollusks, 
the simiiler forms of the more modern dart-bearers having only 
penetrated as far as its northern parts and to the islunds of the 
(Jreater Antilles. 
The region e.xhihits its relationship with South Africa and 
Australasia hy retaining a preponderance of the simjjly organized 
groups which at one perind overspread the whole surface of the globe, 
but appear to bave only differentiated e.xternally in the size, shai)e 
and general character of the shell in response to the varying character 
of the environment they encountered in the course of their great 
migrations, the internal organization lueserving in the main its original 
or primitive simplicity. 
The AVest Indian islands exhibit all tbe peculiarities of pronounced 
insidarity, displaying a remarkable individuality in the preservation of 
a marvellous development of Operculates and of a primitive section of 
Ilpiphallogonous Helices, reproducing in an analogous way the same 
characteristic association of those groups as is found in the Indo- 
Alalayan region, and although the Helices are morphologically low, 
they are yet in advance of the rrotogonous species characterizing the 
Atlantic and (lulf States of North America. 
The Oriental region includes India, Further India and the 
islands adjacent to the e(piator ; it is bounded on the north by the 
