44 
COMPENDIUM OF GEOGRAPHY 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 Hypselostyla ), which are abundant 
in Luzon and the central islands, entirely absent, but two 
well-marked subgenera ( Chrysalis and Prochilus) 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 Calocochlea) are 
universally distributed, occurring on all the islands, and 
it seems probable that these were developed at a time 
when 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 neighbouring 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 ridges the mollusca are of a 
