2 U.S. NATIONAL MUSEUM BULLETIN 257 



existed between North Borneo and the Palawan group of islands as 

 far as Mindoro, which, however, must have been separated earlier 

 than the two preceding. At the same time, along the east side of 

 the archipelago, there must have been another north-south connection, 

 which was disrupted intermittently throughout these periods. Over 

 these land bridges an exchange of northern and southern elements 

 occurred. In addition, it appears certain that there must have been 

 a bridge to Minahassa, the northern peninsula of Celebes, since many- 

 elements of the fauna point in this direction. I have proof of both 

 bridges: characteristic species of the Greater Sunda Islands from Pala- 

 wan and Mindanao. Finally, the marked infusion of the Philippine 

 fauna with Papuan elements suggests the existence of a land bridge 

 between the southern Philippines and New Guinea by way of the 

 North Moluccan Islands. 



The study of zoogeography of the Philippine Islands in respect to 

 some other classes, orders, and grovips of animals is well advanced; 

 for instance, mammals, birds, land moUusks, amphibians and reptiles, 

 fresh-water fishes, Pachyrrhynchidae among the Coleoptera and, 

 finally, butterflies have served for zoogeographical surveys. It is 

 noteworthy that, in general, the results of analysis of these groups 

 are in reasonable accordance with each other, so that it is possible 

 to subdivide the Philippine Islands into a number of biological 

 provinces. 



In general, these provinces reflect the zoogeographic history. 

 The more important ones are; (1) Luzon and dependencies in the 

 north; (2) a central area, partly situated on a shallow plateau, de- 

 fined in the west by Panay, Masbate, Negros and Cebu, and in the 

 east by Samar, Leyte and Bohol; (3) a southern region with Mindanao 

 and Sula Islands, showing correlations mth southern areas such as 

 Celebes and Java, but also having northern elements from the first 

 province, descending along the high moimtain ridge and encompassing 

 the entire east coast of the Archipelago; (4) Palawan and dependencies, 

 ^^dth pronoimced Bornean featiu-es; and (5) Mindoro, more or less 

 independent of the preceding. 



In his classic work, "Die Schmetterlinge der PhUippinischen 

 Inseln," Semper (1896-1902) presented a division of the faima of 

 Macrolepidoptera into eight provinces. His siu-vey was based on 

 over 1500 species of butterflies and moths, but the Microlepidoptera 

 were almost entirely excluded. 



Our knowledge of the faima of Philippine Microlepidoptera, alas, 

 forms quite a contrast with that of the "Macro's." My estimation 

 is that the species enumerated in the present siu-vey amoimt to not 

 more, and probably less, than 20 percent of the existing fauna of 

 these insects. Any specidations on the zoogeography of the group 



