44 COMPENDIUM OF GEOGRAFHY AND TRAVEL 



which more than 200 species have been described, ap- 

 pears to be quite peculiar to the Philippines, — the few 

 extra-Philippine forms which have been referred to it 

 being better grouped elsewhere. The Sandwich Islands 

 alone in the Pacific form another instance of a group of 

 islands possessing so large and so well-marked a genus of 

 peculiar land-shells. 



A study of the various subgenera of Cochlostyla reveals 

 several facts of importance. Firstly, with regard to the 

 island of Mindoro, it appears that not only are two of 

 them {Orthostylus and Hypsclostyla), which are abundant 

 in Luzon and the central islands, entirely absent, but two 

 well-marked subgenera {Chrysalis and Prochihis) occur 

 which are found nowhere else in the archipelago. The 

 small island of Luban, to the north-west of Mindoro, 

 also has a peculiar subgenus. Siquihor, an island of 

 equally small size lying between Mindanao and the 

 central group, is likewise conspicuous as possessing the 

 only species of Clausilia known from the Philippines. 

 Three subgenera {Chlorcea, Corasia, and Calococlilca) are 

 universally distributed, occurring on all the islands, and 

 it seems probable that these were developed at a time 

 wdien the Philippines were all united together, or, at all 

 events, were much less of an archipelago than they now 

 are. It is evident, from their isolation being so specially 

 marked, that Mindoro and Luban became separate at a 

 very early period. 



With regard to the land mollusca in general, and 

 their relation to the neis;hbouring lands and islands, Mr. 

 A. H. Cooke remarks that two distinct faunae, the Indo- 

 Malayan and the Polynesian, find their meeting-place in 

 the group. Palawan and the Sulu Islands form two 

 arms or ridges which tend to connect the Philippines 

 with Borneo. On these ridses the mollusca are of a 



