1892.] THE LAND-MOLLUSCA OF THE PHILIPPINES. 461 



Thus Basilan is, as might be expected, thoroughly Philippine, 

 not possessing even one peculiar species. 



The MoUusca known from Malanipa are : — 

 Xesta mindanaensis, Semp. Also occurs in Mindanao, 

 CJiloritis sanziana, H. & J. „ Mindanao. 



Ohbina higonia, F6r. „ Mindanao, Leyte, Samar. 



Leptopoma vifreum, Less. „ Philippines generally. 



The only MoUusca which appear to be known from Soo-loo are: — 

 Trochomorpha metcalfei, Pfr. 

 Cochlostyla lais, Pfr. 

 Melania soolooensis, Brot. 

 ^ Gyclotus suluanus, Mollf., MS. 



According to Hidalgo^, Cochl. lais occurs in N. Mindanao. The 

 species is probably only a variety of puella, Brod. Pfeiffer originally 

 described it from the Philippines generally ; in the ' Novitates,' iv. 

 tab. 126. ff. 6, 7, p. 114, he figures a var. said to be from Tukan 

 Bessi, a locality which I greatly doubt. 



In the absence of any information as to Tawi-tawi, it is impossible 

 to say how far Philippine influence extends along this ridge. 



The MoUusca known ^ from Bongao are : — 



Plectotropis squamulifera, Mollf. Peculiar. 



Macrochlamys angulata, Mollf. Peculiar. 



Trochonanina conicoides. Mete. Peculiar. 



Opeas, two species not identified. 



Opisthoporus, sp. (possibly a Gyclotus). 



Leptopoma, sp. 



Lagochilus quinqueliratus, Mollf. Peculiar. 



Alycceus excisus, Mollf. Peculiar. 



Diplommatina roebelini, Mollf. Peculiar. 



Pupina ottonis, Dohrn. Also occurs in Philippines. 



Helicina martensi, Issel. „ Borneo. 



Thus six out of the eight known species are peculiar, while of 

 the remaining two, one occurs in the Philippines and one in Borneo. 

 As to genera, no exclusively Philippine genus occurs, while Plecto- 

 tropis, Macrochlamys, Trochonanina, Opisthoporus, Lagochilus, and 

 Alycceus are Indo-Malay. In spite, then, of the deep intervening 

 channel, Bongao is distinctly Bornean, and, in spite of the chain of 

 . islands with shallow water between them, distinctly non- Philippine. 



Coming to the western ridge, the MoUusca known from Balabac * 

 are as follows : — 



Amphidromus ^ 1 entobaptus, Dohrn. Also occurs in Palawan. 



^ In the Brit. Mus., from the Hungerford collection. 



^ Journ. de Conch. 3*= ser. xxxv. p. 113. 



3 Von MoUendorff, Jahrb. deutsch. malak. Gesell. siv. p. 286. 



* From the island of Balambangan, on the Bornean side of Balabac Strait, 

 are recorded Ariophanta regalis, Bens., and Cyclophorus tenebricosus. Ad. and 

 Rve., and from an islet between Banguey and Balambangan, Amphidfomus 

 adamsii, Reeve. 



5 This is the species called by Hidalgo contmrius, MilU., which occurs in 

 Timor. 



Proc. Zool. SOC.--1892, No. XXXII. 32 



