ILLUSTRATIVE OF NATURAL SELECTION. 189 



Section D contains the strongest-bodied and most 

 swift-flying of the genus. They love sunlight, and 

 frequent the borders of streams and the edges of 

 puddles, where they gather together in swarms con- 

 sisting of several species, greedily sucking up the 

 moisture, and, when disturbed, circling round in the 

 air, or flying high and with great strength and 

 rapidity. 



Geographical Distribution. One hundred and thirty 

 species of Malayan PapilionidjB are now known within 

 the district extending from the Malay peninsula, on 

 the north-west, to Woodlark Island, near New Guinea, 

 on the south-east. 



The exceeding richness of the Malayan region in 

 these fine insects is seen by comparing the number 

 of species found in the different tropical regions of the 

 earth. From all Africa only 33 species of Papilio are 

 known ; but as several are still undescribed in collec- 

 tions, we may raise their number to about 40. In all 

 tropical Asia there are at present described only 65 

 species, and I have seen in collections but two or three 

 which have not yet been named. In South America, 

 south of Panama, there are 150 species, or about one- 

 seventh more than are yet known from the Malayan 

 region ; but the area of the two countries is very dif- 

 ferent ; for while South America (even excluding Pata- 

 gonia) contains 5,000,000 square miles, a line encircling 

 the whole of the Malayan islands would only include an 

 area of 2,700,000 square miles, of which the land-area 

 would be about 1,000,000 square miles. This superior 



