THE PHILirPINE ISLANDS 45 



mixed type — partly Philippine, partly Indo-Malayan ; 

 but there can be little doubt that they have formed, at 

 a period more or less remote, the passage by which the 

 Indo-Malayan mollusca have entered the archipelago to 

 mingle with the indigenous genera. Thus we find the 

 great Nanincc and Cyclophori of the Sunda Islands largely 

 represented, as well as Amphidromus, Kaliclla, and others, 

 all of which are represented in Java, Sumatra, and 

 Borneo, as well as in India or Indo-China, but scarcely 

 at all, or in greatly diminished numbers, in the islands 

 farther east. 



The Polynesian and eastern connection is exemplified 

 by the occurrence of Tornatellina, Eudodonta, niunerous 

 species of Hclicina and Leptopoma, and a considerable 

 number of Pupina and Diplommatina. About fifteen 

 species of land shells are common to the Philippines and 

 Amboina, and some w^riters have considered it probable 

 that a land connection existed at one time with the 

 countries to the east and south, but in this opinion Mr. 

 Cooke does not share. 



Prom the foregoing it will be seen that the zoology of 

 the group is of unusual interest, presenting problems in 

 geographical distribution wdrich have as yet not been 

 satisfactorily explained. Taking all the facts yet known, 

 we find a wonderful amount of peculiarity throughout, 

 great luxuriance of development in some of the lower 

 groups, and many deficiencies in the higher, especially in 

 the mammalia. This luxuriance and peculiarity, com- 

 bined with poverty in the forms of life, implies great 

 antiquity and long - continued isolation from adjacent 

 countries. The presence of a tolerable variety of mam- 

 malia, closely alHed to those of other Malayan countries, 

 shows that the time from which the isolation dates is 

 not very remote geologically ; but it is less easy to 



