200 THE ANIMALS OF MADAGASCAR 



blackish shell, and others of Bithynia, are quite unlike the Ethiopian representa- 

 tives of these genera, but near akin to Indo-Malay forms. 



Of crayfishes, Madagascar has the genus Astacoides, allied to Australian, 

 New, Zealand, and South American types, thereby displaying another marked 

 point of difference from Africa. 



As regards the insects of Madagascar, the following extract from Dr. A. R. 

 Wallace's Geograjjhical Distribution of Animals puts the matter in a brief but 

 clear form : — 



"Taking the insects as a whole, we find the remarkable result that their 

 affinities are largely Oriental, Australian, and South American ; while the African 

 element is represented chiefly by special South African or West African forms, 

 rather than by such as are widely spread over the Ethiopian region. In some 

 families [of beetles] — as Cetoniidce and Lamiidce — the African element appears 

 to preponderate ; in others — as CicindelidcB — the South American affinity seems 

 strongest ; in Carabidce perhaps the Oriental ; while in Buprestidce and Ceram- 

 bycidce the African and foreign elements seem nearly balanced." 



The foregoing brief sketch of the leading features of its fauna is amply 

 sufficient to indicate the propriety of regarding Madagascar as a zoological region 

 by itself, this Malagasy region standing on the same level as the Ethiopian and 

 the Oriental regions of Arctogsea. This view is now adopted by a considerable 

 number of naturalists, although the study of the geographical distribution of 

 bird-eating and trap-door spiders has induced one investigator to adopt the older 

 view that Madagascar forms part of the Ethiopian region. With this exception, 

 it is interesting to note that the geographical distribution of trap-door and 

 bird-eating spiders denotes that the zoological regions into which the world 

 may be mapped out from the evidence of this group are practically identical with 

 those indicated by mammals and birds. The importance of this can scarcely be 

 over-estimated. 



