( &13 ) 



the past history of the earth and its inhabitautt , the minor zoogeographical districts 

 have by most authors been delimitated according to differences which are the effect 

 of biological factors. Considering, however, that different environment, such as 

 forest, open land and desert, fresh and salt water, naturally gives subsistence to 

 different animals, and that therefore physiographically different districts a py-iori 

 are known to have a different fauna, the division of the earth's surface in 

 such zoogeographical districts as are identical with physiographical districts 

 (Sharpe's West African Subregion = district covered with forest ; Merriam's 

 Sonoran Subregion of North America = arid country) is as snch of very little value, 

 concerning more the geographer than the zoologist. And taking further into 

 account that we now know perfectly well that in every district where the physio- 

 graphical (and meteorological) conditions are different from those of other districts 

 these differences are accompanied by modifications of the characters of some of the 

 animals, the simple statement that a certain number of the inhabitants are different 

 from the representative forms of the adjacent districts is, like the mere record of 

 the discrepancy in the composition of the fauna, of little conserpience for science, as 

 from those statements as such no new general conclusions can be drawn. The 

 biological branch of the study of the geographical distribution of animals, therefore, 

 must have another aim, and that is to be to Zoology what the geological branch is 

 to Geology, namely an adjunctive science which, by a comparative study of the 

 differences in the environment and those in the animals, may help greatly to find 

 the causal connection between the modifications in the organs of the animals and in 

 the environment (in the widest sense), and thus conld reveal to us the history of the 

 descent of the forms of animals. 



For the sake of illustration let us apply these conclusions to the Papilio fauna 

 of a small area, for instance the lesser Sunda Islands. We select this group of 

 islands for two reasons : firstly, because the discrepancy existing between their 

 fauna and that of the larger Sunda Islands has been accounted for by Wallace by 

 geological factors ( Wallace's lifie) ; and secondly, because our conclusions derived 

 from the Papilios stand in ojjposition to those which Wallace derived from the 

 avifauna. As a complete exposition of the zoogeographical relations of the islands 

 between Lombok and Timor* would be much too extensive for our present purpose, 

 we will restrict the discussion chiefly to the two questions : (1) what conclusions can 

 we draw from the' composition of the Papilio fanna of the lesser Sunda Islands with 

 respect to the geological history of the group of islands ? and (2) is there anything 

 in the distinguishing characters of the Papilios which can serve to solve a question 

 relating to the phylogeny of animals ? 



The islands of Lombok, Sambawa, Sumba eastward as far as Lctti and Moa, are 

 inhabited by fifty odd different forms of Papilio, which we can arrange in eighteen 

 series of closely allied representatives. Of these eighteen series one (cafiopiis-series) 

 is distributed farther east over the Tenimber Islands and North Australia to the 

 New Hebrides, but has also some allies in the Indo-Malayan Region; the perant/ius- 

 series occurs from Java to New Guinea, but is aljseut from Australia ; another, 

 halipkron-SitviGs, is found in Celebes and not in the lndo-;\Iiilayan Region ; a fourth, 

 antiplmti's-aeviiiii, is found all over the Indo-Malayan Region, Celebes, and the 

 Northern Moluccas, but is absent from the Southern Moluccas, Australia, New 

 Guinea, and the islands farther east. Seven series reappear in the ludo-JIalayau 



• Compare also Doheity, Thr HiittirtlUn of Siimba ami Sambawa, in Juiini. As. See. licng. 1S!)1: 

 Pagenstecher, Uiber die LeyiduptirLn von Humba vnd Sambawa, in Julirb. A'asit. T'cr. .V«/. 1896. 



