ANNIVERSARY ADDRESS OE THE PRESIDENT. 87 



necessity for land-connexion between the remaining islands and 

 New Guinea ; for if the snakes and frogs came over the sea to all 

 the other islands, why have they not reached San Cristoval ? 



It is evident that the separation of the Solomon group of islands 

 from the mainland and from each other is due to subsidence. This 

 appears at fii'st opposed to the geological evidence of elevation, and 

 it undoubtedly proves that the islands, none of which are 12,000 

 feet high, cannot as a whole have been recently elevated 12,000 

 feet unless, since the elevation took place, they have undergone 

 depression sufficient to isolate them. But the raised coral- and 

 rhizopod-beds described by Dr. Gruppy certainly appear to bear out 

 his views of recent elevation, and he brings forward other evidence 

 of much weight. On the other hand, not only are some of the 

 forms of batrachia and reptilia peculiar, but the rodents, and espe- 

 cially the bats, show striking distinctive characters. Two new 

 genera of fruit-eating bats (Pteropidce) and one of WiinolopMdae 

 have been recently described from the Solomon Islands, and are not 

 known to occur elsewhere. It is therefore probable that the Solo- 

 mon Islands must be ancient land, and the explanation of the 

 apparent contradiction may be that the elevation observed by Dr. 

 Ouppy has been partial and local, and has not extended to the 

 whole area. It is also probable that the depression which has sepa- 

 rated the different islands, with the exception of San Cristoval, 

 from each other is much more recent than that which divided the 

 group as a whole from New Guinea. It is far from unlikely that 

 the channel separating San Cristoval from the other islands will be 

 found, when accurate soundings are taken, to be deeper than the 

 channels between the remaining islands of the group. 



Another instance similar to that of the Solomon Islands is 

 afforded by the Liu-Kiu (Loo-choo) Islands between Japaii and 

 Formosa. Here also the depths of the surrounding seas are not, I 

 believe, ascertained; the islands are represented in the ^Challenger' 

 map, like the Solomons, as within the 500-fathom line. Prom these 

 islands several lizards, land-snakes, and batrachians, including a 

 newt, have been obtained*. Most of the species are peculiar, but 

 one frog is a common oriental form, and the newt is a variety of a 

 Chinese and Japanese species. 



3. The Mozambique Channel between Africa and Madagascar. — 

 Before passing on to the question of an ancient land connecting 



* Boulenger, P. Z. S. 1887, p. 146. 

 VOL. XL VI. a 



