456 REV. A. H. COOKE ON [May 17, 



related to one another. They have no subgenus peculiar, but their 

 general relations are rather with Luzon than with the central islands. 

 One species of Phengus indicates relations with Marinduque, while 

 the complete absence of Hypselostyla, so common in Panay, separates 

 them from the central group. 



Cebu and Bohol. — These islands, with Panay, are the metropoHs 

 of Hypselostyla, which has spread northward to Luzon. Both are 

 sharply separated from Mindanao, since neither Orthostylus, which 

 is abundant in Cebu and Bohol, nor Hypselostyla is represented in 

 that island, while on the other hand Eudoxus, which is abundant in 

 Mindanao, is entirely absent from Cebu and Bohol. Corcisia is 

 abundant in both islands ; Axina is not recorded from Bohol, while 

 it is abundant in Cebu, which indeed contains 6 out of the 10 existing 

 species. Calocochlea, on the contrary, which is entirely absent from 

 Cebu, occurs freely in Bohol \ 



Panay. — This island appears, on a consideration of its fauna, to 

 be rather isolated ; but perhaps this may be accounted for by the 

 fact that its nearest neighbour, Negros, has been scarcely explored. 

 Its relations are with the central group, Hypselostyla being abundant 

 and all its species peculiar to Panay. Orthostylus is the only other 

 subgenus known to occur. Thus no connection is indicated with 

 the Tablas-Romblon-Sibuyan group or with Mindoro. 



Mindanao (including Surigao and Camiguin). — This great island 

 presents some remarkable features. Axina is entirely absent, while 

 Calocochlea is exceedingly abundant. Corasia appears to be con- 

 fined to the extreme S., where it is abundant. Phengus, Helicostyla, 

 and Cochlodryas are absent, and, what is more remarkable. Ortho- 

 stylus and Hypselostyla, so abundant on Cebu and Bohol, do not 

 occur, thus indicating a very considerable severance between 

 Mindanao and the central islands. The channel immediately north 

 of Mindanao is not well surveyed, but appears undoubtedly to be of 

 very considerable depth, 185 fathoms having been recorded by the 

 ' Challenger ' close under the N. coast of Camiguin. The Surigao 

 strait appears to be rather shallow on its eastern side, but as it opens 

 out towards the west the depth appears rapidly to increase. A 

 special feature of Mindanao is the development of Eudoxus, found 

 elsewhere only in Luzon (?) and Catanduanes ^. So far as we can at 

 present make out the relations of Mindanao are rather with Luzon 

 than with the islands immediately contiguous. 



There seems every probability that the western part of Mindanao 

 was once for a considerable time a separate island, completely dis- 

 connected from the central and eastern portions. The low and 

 narrow neck of land, scarcely 20 miles across, lying between liigan 



^ Hidalgo (Journ, de Oonch. 3^ ser. xxvii. p. 175) gives Cebu as a habitat for 

 calohapta, Jon. This must be a mistake, as the species is a ProcMlus, which is 

 confined to Mindoro and, perhaps, the Cuyos. 



^ Hidalgo (Journ. de Conch, tii sup. p. 146) gives C. roissyana from "Surigao, 

 dans I'ile de Mindanao." I do not know any other authority for believing that 

 rois&yana is not peculiar to Mindoro. There is probably a misidentification of 

 C. spharmi, Sowb. 



