86 TROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



explaiued without communication by land. The species have been 

 described by Mr. Boulenger * and comprise — 1 crocodile, 17 lizards, . 

 10 land-snakes, and 13 species of frogs and toads belonging to 5 

 genera, representing 3 families, Banidce, Ceratohatmchidce, and 

 IIylid(^, the second of which, so far as is known at present, is 

 peculiar to the islands. Our knowledge of Papuan batrachians is, 

 however, very imperfect. 



It is a well-known fact, as I have already mentioned, that batra- 

 chians and their eggs are killed by sea-water, and that snakes, as a 

 rule, are not found on oceanic islands. No batrachian or ophidian 

 fauna resembling that of the Solomon Islands has ever been observed 

 except in islands that have been part of a continental land. It is 

 impossible to come to any other conclusion than that the Solomon 

 Islands, with New Britain and New Ireland, once formed part of 

 New Guinea, and that portions of the group have never been sub- 

 merged since the separation. 



Nor is this quite all the evidence. The species of frogs and 

 snakes appear to be pretty generally distributed amongst the islands 

 in such a manner as to show that the fauna is probably nearly 

 uniform throughout, with the exception of the easternmost island, 

 San Cristoval, the fauna of which is rather well known. Whilst 

 from the next large island to the westward, Guadalcanar, 5 frogs 

 and 4 snakes have been obtained, San Cristoval has only yielded 

 1 frog and 3 snakes. IVIoreover, 2 of the 3 snakes belong to the 

 genus Enygrus of the family Boidce, probably all good climbers and 

 swimmers. Both the species of Enygrus are widely dispersed, one 

 ranging eastward to the Fiji Islands, the other northwestward to the 

 Moluccas and Pelew Islands. The third snake, JDendrophis sdlomonis, 

 found also in Duke of York Island, between New Ireland and 

 New Britain, and in several other islands of the Solomon group, is 

 a climbing tree-snake, that might be transported by floating trees. 

 Most snakes are unable to climb trees, and would be washed off 

 from floating branches &c. In other respects, too, the reptilian 

 fauna of San Cristoval, as Mr. Boulenger has shown, is Polynesian ; 

 whilst Mr. Woodford has pointed out (P. Z. S. 1888, p. 250) that 

 certain birds and butterflies, found in the other islands, are hero 

 wanting. Probably San Cristoval was separated from the main- 

 land before the other islands, just as Ireland must have been sepa- 

 rated from continental Europe before Great Britain. But the poverty 

 in batrachians and snakes of San Cristoval serves to confirm the 



* Tr. Z. S. xii, p. 35; P. Z. S. 1887, p. 333, 1888, p. 88. 



