Land- Shells of the Sulu Archipelago. 19 



The specimens just received by the British Museum were 

 collected by Mr. A. Everett at the Tawi-Tawi group, on the 

 islands of Sibutu, Bongao, Bilatan, and Tawi-Tawi itseit", all 

 of these being situated at the western part of the archipelago. 



No laud-shells have previously been recorded from any 

 of these islands with the exception of Bongao. From this 

 locality Dr. ^liillentlorff has given a list of twelve species. 



The terrestrial moUusks from the remaining islands of the 

 Sulu Archipelago are practically unknown, only two or three 

 forms having been mentioned as occurring on Sulu itself *. 



The Rev. A. H. Cooke, in his instructive paper " On the 

 Geogra])hical Distribution of the Laud-Mollusca of the Philip- 

 pine Islands, and their Relations to the Mollusca of the 

 neighbouring Groups " tj has arrived at certain conclusions, 

 which, in light of the material now at hand, appear altogether 

 untenable. Commenting upon MoUendorff's list of species, 

 he observes : — " 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 Plectotropis^ MacrochlamySj 

 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." 



In the first place, I would observe that Trochonanina coni- 

 coides X is not peculiar to Bongao, as he states, for it was 

 described many years ago from Borneo, and has been recorded 

 from that locality over and over again. Also it must not be 

 supposed that the above genera quoted by Mr. Cooke as 

 " Indo-Malay " have no representatives in the Philippines. 

 Of Macrochlamys there are several species ; Trochonanina is 

 represented by one or two forms ; of Lagochilus Mr. Cooke 

 himself, in another part of his paper, enumerates nine j and of 

 AlyccBus two species are recorded from Luzon. One Plecto- 

 tropis at least has been found in the Philippines ; and Opistho' 

 porus^ occurs in Palawan, which is quite as much Philippine 

 in its molluscan fauna as Bornean. 



The following table (p. 51) shows at a glance the relative 



* Trochomorpha Metcalfei, Corasia lais, and Cyclotus suluanm. 



t Proc. Zool. Soc. 1892, p. 461. 



X The species here referred to is not the true T. conicoides, but a 

 distinct species, viz. T. bongaocnsisy inihi. 



§ Tliis genus is not known with certainty from Bongao, and the youtig 

 shell doubtfully referred to it by Mollendorff and quoted by Cooke is, in 

 all probability, tlie Cyclotus variegatus obtained there by ^Ir. Everett. 



Ann, 6c Mag. N. Hist. Ser. 6. Vol. xiii. 4 



