3 I O CELEBES CHAP. 



sented. Hemi'plecta and Xcsta aie abundant and large, while the 

 Bliysota of Borneo contain some huge 'sinis- 

 tral forms. lihodina is a remarkable form 

 from Malacca, whose exact generic position 

 is not yet settled. Clausilia has a few species 

 on all tlie islands, the last occurring on 

 Ternate, and a single Pcqniina (Moluccas 

 and X. Guinea) occurs in Borneo. 



The Island of Celebes marks the lie- 

 ginning of a distinct decrease in the Indo- 

 Malay element. The Naninidae lose ground, 

 in proportion to the Helicidae, Macro- 



cTtla/inys, for instance, l)eing represented hj 

 Fig. 209. — Amphidromus -, . i rr ■ i j -i n 



perversus L.. Java. ^'11^7 ^''^^^ species, and Hcmiinccta by lour. 



Other characteristic genera of the Indian 



region dwindle, such as AvvpliidTomus, Clausilia, the tubed 



operculates, and Cyclopliorus, Avhile SitaJa, Kaliella, Glessula, 



and Plcctotropis disappear altogether. . Comparing the total 



numljers of JSTaninidae and Helicidae from Sumatra to New Guinea, 



we obtain this interestin«: result : 



It will be noticed that the proportion of Xaninidae to Helicidae, 

 which has been nearly 4 to 1 in Sumatra, falls to 3 to 1 in Java, 

 and rises again to 4 to 1 in Borneo (showing the essentially con- 

 tinental character of the island) ; in Celebes it further falls to 3 

 to 2, while in the Moluccas the scale turns and Helix has the 

 advantage by about 8 to 5, and in X. Guinea by more than 

 2 to 1. 



There is the same absence of marked features of individuality 

 in Celebes as in the islands dealt with above. Not a single 

 genus is peculiar. The nature of the sea bottom between Borneo 

 and Celebes, with its indications of a somewhat broad bridge over 

 an otherwise deep channel of separation, would seem to account 

 for and suggest the true explanation of the facts as they stand. 

 At the same time, there are indications of a certain amount of 

 contrast between N. and S. Celebes. The Indian element, which 

 constitutes the preponderating majority of the fauna, is common 

 to nortli and south alike. But the north part of the island, in 



