PROBLEMS OF DISTRIBUTION AND THEIR SOLUTION. 167 



of the Galapagos number 57 species 38 species being peculiar to 

 the islands. But the study of the birds is rendered extremely inter- 

 esting by the fact that we notice amidst their ranks all shades of 

 likeness and divergence from continental forms. Some species are 

 identical with American birds, whilst others are different from well- 

 nigh all other bird forms. Thus there is the rice-bird of Canada 

 and the United States remaining unchanged in the Galapagos Islands ; 

 whilst the short-eared owl, which, as Mr. Wallace says, " ranges from 

 China to Ireland," evinces a slight variation in its Galapagos form 

 from the familiar home bird. The finches and sugar-birds of the 

 Galapagos exist as distinct genera, and represent forms which, restricted 

 in range even in South America, have kept their chief peculiarities 

 intact, and have developed others sufficiently distinct to render their 

 race peculiar to these islands. Casual migration, along with a com- 

 paratively undisturbed residence in these islands, together explain 

 the distinct character of the bird-population, as well as of the lower 

 denizens of the Galapagos. 



If the effects of land-separation and isolation are typically 

 witnessed in the case of the "oceanic" islands, the opposite results 

 of recent land-connections with continental areas are seen in the 

 history of the "continental" islands. Of these islands Great Britain 

 and Ireland form typical examples, as likewise do Japan, Borneo, 

 Java, and other areas. The "continental" islands evince a close 

 connection with the mother-land in the usually shallow sea not as a 

 rule exceeding 100 fathoms in depth which separates them from the 

 continent. They possess quadrupeds and reptiles, and these animals, 

 along with the remaining fauna, exhibit, as a rule, a close likeness to 

 the life of the larger area. All around the British Isles the 100- 

 fathom line persists, and joins Britain to Denmark, Holland, Belgium, 

 and France, as well as to Ireland on the west. The geological 

 proofs of our "recent" union with the continent are numerous and 

 indisputable. Probably after the greatest intensity of the glacial 

 epoch, Britain joined the continent for the last time ; and as our 

 quadrupeds are identical for the most part with those of France and 

 the continent, there can be little hesitation in endorsing the geological 

 opinion from the zoological standpoint. Possibly submergence after 

 Britain received its continental migrants, may account for our paucity 

 of species, when compared with continental life ; this subsidence 

 destroying and limiting what would otherwise have been an abundant 

 fauna. For we discover that whilst Belgium has 22 species of reptiles 

 and Amphibia, Britain possesses but 13, whilst Ireland has but 4 

 species this latter result being due to the depth of the Irish Sea, 

 which is greater than that of the German Ocean: a fact pointing to the 

 more remote separation of Ireland, as compared with the continental 

 connections of Britain. Our islands possess, it must be remarked, 



