SOLOMON ISLANDS. 59 



between New Guinea and these islands is an older one than that between New 

 Guinea and the Moluccas. 



vSoLOMON Islands. 



The Solomon Islands consist of a long chain of high mountainous islands, 

 many of them of considerable size, stretching away to the southeast from the 

 Bismarck group, and lying parallel to the coast-line of southeastern New Guinea. 

 There is really good reason for recognising the Solomon Islands as being of 

 sufficient zoologic differentiation to warrant their separate consideration from 

 the Bismarck group. To be sure, the islands are of much the same character 

 and size; none of them being quite as large, however, as either New Pomerania 

 or New Mecklenburg. Generally speaking they are now fairly well known, 

 thanks especially to the researches of Guppy some years ago. His collections 

 were reported upon by Boulenger (Trans. Zool. soc. London, 1886, 12, p. 35-62, 

 pi. 7-13). 



From some points of \'iew the difference between these two faunae are in- 

 significant. It is most unfortunate that we have so few hydrographic data on 

 this area. Soundings are few and far between upon all sides of the group, and 

 they do not show anything of the submarine relationship between these two 

 groups of islands and the Papuan mainland. It seems very hkely from the condi- 

 tions of the fauna that the Solomon Islands, or some of them at least, remained 

 connected and formed a single land-mass for a very considerable time after their 

 separation from the region of the Bismarck Archipelago took place. This is 

 suggested by the fact, as will appear later, that a number of most characteristic 

 autogenous forms occur upon many of the islands, while they do not occur in 

 the Bismarck group. On the other hand, it is worth noting, as Boulenger has 

 already said (Proc. Zool. soc. London, 1888, p. 89), that between the" extreme 

 islands, Faro to the northwest, and San Cristoval towards the southeast, there is 

 considerable difference in the abundance and variety of amphibian life; Faro 

 being strongly Papuasian, and the other end of the group far less so. This 

 immediately suggests that the islands separated from one another progressively 

 from the lower end of the chain; or, in other words, that the subsidence, if this 

 be considered the cause of their separation, began with the depression of the area 

 to the southeast of the group, and continued in a more or less northwest direc- 

 tion. This seems reasonable, inasmuch as New Caledonia, though obviously 

 a continental island, with a fauna derived over a previous land connection, lacks 

 snakes and amphibians; while the Fijis, lying nearer to the source of supply, 



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