ENGANO. 19 



The snakes in this case do not outnumber the Uzards in multiplicity of species 

 as they do on Nias. This, again, is undouljtedly due simply to the fact that we 

 do not know the island thoroughly. There are eleven species known, none of 

 which are peculiar to the island, nor are any of them otherwise of particular 

 interest. 



The amphibians, as with Nias, simply serve to emphasize the close Sumatran 

 affinity of the fauna. It is interesting to note the presence again of Ichthyophis 

 glutinosus. Four species of amphibians — namely, Polypedates appendiculatus, 

 P. pardalis, Calophrynus pundatus, and Nectophryne guentheri — are all known 

 from Sipora, but as yet none has been found in Sumatra. These forms are all 

 known either from the mainland, or from Borneo and the Philippines; and it is 

 almost certain that future investigation will show that they occur on Sumatra 

 as well. Van Kampen has pointed out that three of the Sumatran frogs, viz. — 

 Rana nicobariensis, R. labialis, and R. microdisca, were all known from small 

 islands about Sumatra before they were found on the great island itself. It is 

 remarkable that no Philautus (Ixalus) has been found on any of these islands 

 off the coast of Sumatra or upon Sumatra itself, for we should suppose from the 

 distribution of the genus that it would have been found there long ago. It is 

 hardly conceivable that it does not occur. Its absence from the islands off the 

 coast would surely seem to emphasize the fact that they have not served as a 

 bridge between the mainland and Java, as has been suggested by some writers. 



It is most unfortunate that no data are as yet available regarding the faunae 

 of either Siberut or of the two Pagi Islands; and it is still more unfortunate that 

 there are not sufficient soundings to establish definitely the presence or absence 

 of a ridge connecting Mega with Engafio Island. Mega seems to lie on an 

 extension of the same great submarine hook of which the Mentawei Islands 

 are simply the parts remaining above the surface of the water. 



Engano. 



The single small island of Engano occupies the most isolated position of 

 any of the islets off the Sumatran coast, for it is distant over a hundred miles 

 from Mega, which may be considered the southernmost of the Mentawei group ; 

 the nearest point on the shore of Sumatra itself is distant about sixty miles. 

 The island would appear to be similar in its physical characteristics to the ones 

 which we have been discussing, though it is considerably smaller than Sipora, 

 and far less in size than Nias. It is about twenty miles in length by ten to 

 twelve in width. Unfortunately the soundings on the Dutch chart and on the 



