ACULEATE HYMENOPTERA AND ICIINEUMONTDiE. 209 



Britain) every species in the smaller will be found also in the 

 larger tract of land, or a very long disconnexion, in which case 

 (as in that of Madagascar) every species and many genera, and 

 even families, will be peculiar to the smaller island. It would 

 hardly be expected, though it is undoubtedly the fact, that land- 

 birds (with few exceptions) exhibit the same phenomenon in 

 almost an equal degree with mammals, showing that their mi- 

 grations are comparatively rare and involuntary, except in the 

 case of some preeminently wandering orders and families. These 

 principles can be applied with great facility in the Malay archi- 

 pelago, which can thus be divided into groups of islands having 

 well-marked mutual relations. 



First, we have a great division into two regions, each of which 

 is well characterized by many distinct families of mammals and 

 birds, for some details of which see " Zoological Geography of the 

 Malay Archipelago," in ' Proceedings of Linnean Society,' Zool. 

 vol. iv. p. 172, and ' The Malay Archipelago ' (Macmillan and Co., 

 1869). We thus find that one half of the archipelago belongs to 

 the Indian, the other to the Australian region. In the Indian 

 portion of the archipelago, which may be termed the Indo- 

 Malayan subregion, we find that the islands of Java, Sumatra, 

 and Borneo, together with the Malay peninsula, have the closest 

 resemblance in their natural productions — numbers of species 

 being identical in all, and the same groups, for the most part, oc- 

 curring throughout ; they form therefore one subdivision, which 

 may be called the Indo-Malay islands proper. The Philippine 

 Islands have certain relations to these, but have several distinctive 

 characteristics. They are deficient in several groups which run 

 through all the other islands, and they contain several genera which 

 show a connexion with Celebes in the Australian region, as well 

 as others which indicate a relationship with Chinese Asia. 



In the Australian region, New Gruinea is the most important 

 and characteristic island, possessing numerous genera of its own ; 

 but immediately surrounding it are several islands (Aru, Mysol, 

 Waigiou, &c.) which so closely agree in all important points as 

 to indicate that they form a single district, which may be termed 

 that of the " Papuan Islands." The large group of islands 

 generally known as the Moluccas has a great resemblance to the 

 Papuan group ; but several important genera are absent, and the 

 islands possess several common characters : they will form the 

 " Moluccan group." The large island of Celebes is very peculiar, 



