304 Mr. A. R. Wallace on 



By a consideration of ilie facts presented by the distribution 

 of Birds and Mammals, it has been proved that the Malay 

 Archipelago really belongs to two primary zoological divisions 

 of the earth. A line drawn on the east side of the Philippines, 

 curving to the west of Celebes, and passing between the islands 

 of Baly and Lombock, will divide the Indian from the Australian 

 region. Mr. Pascoe however is of opinion that this division 

 will not hold good for insects, as he finds that in Coleoptero, 

 and especially in Longiconua, New Guinea and the Moluccas 

 have a much greater resemblance to Borneo and Malacca than 

 they have to Australia. If this statement expressed the whole 

 of the facts of the distribution of these insects, it would un- 

 doubtedly tend to prove that no very general causes have 

 determined the distribution of organic life, and that we could 

 therefore not hope to mark out such zoological regions of the 

 earth as would be alike useful to the students of every branch of 

 natural history. But I believe that along with this general 

 resemblance of the Coleopfcra from the two extremities of 

 the Archipelago, there is also a diversity that points to the same 

 division that is so strikingly manifested in the distribution of the 

 higher animals. As examples I may mention the great and in- 

 teresting Longicorn suh-CamWy of Tmedsternilcp conhned to the Aus- 

 tralian region, although, owing to unfavourable conditions, almost 

 absent from Australia itself. Cyphogastra, which Deyrolle con- 

 siders one of the best marked genera of the family of Buprestldce, 

 and Eupholus among the Curcullonidce, are similarly restricted ; 

 while the metallic Elateridcs (Campsosternus), the g'\ant Buprestidco 

 of the genus Caloxantha, and the splendid phytophagous Sagrce, 

 are bounded in the western half of the Archipelago by the line 

 above indicated. Such cases as these (and I feel sure they are 

 much more numerous than is yet believed) would show that even 

 the distribution of the Coleoptera is largely influenced by the 

 same general causes which have more powerfully affected other 

 groups ; and I believe the cause of the anomaly presented by this 

 order is to be found in the fact, that, in the grand and luxuriant 

 forests which cover the whole Archipelago, almost all the Cole- 

 optera are more or less intimately associated with dry or decaying 

 timber. The larvae of all the most prominent groups are lig- 

 nivorous, and even the Carabidce mostly dwell under dry or 

 rotten bark. This circumstance is evidently in the highest 

 degree favourable to the diffusion and intermingling of the pro- 

 ductions of the different islands, and as the general physical 



