XXXVll 



configuration of lands lias remained pretty nearly the same, to 

 have stocked distant islands with their existing species. In 

 these discussions it is essential to bear in mind an important 

 generalization of Mr. Darwin, namely, that the chance of the 

 permanent establishment of immigrants as species in a locality is 

 in inverse proportion to the degree in which the locality is already 

 well-peopled with similar forms. On this view, a land newly emerged 

 from the sea, or with a stock of species diminished by extinction, 

 would in course of time be appropriated by the waifs and straj^s 

 which are brought to its shores. These considerations have been 

 well kept in view by Mr. Godman in an admirable paper on the 

 birds collected by him in the Azores, where the fauna, to a much 

 larger extent than in the other Atlantic islands, is made up of 

 species identical with those of other lands, chiefly Western Europe, 

 from which direction blow the prevailing winds. In islands like the 

 Madeiran and Canaries groups, where there is a large proportion of 

 endemic and peculiar forms, a great geological antiquity of the land 

 must be inferred. There may have been, it is true, a former con- 

 nection of the islands with a larger tract of land, when these 

 peculiar forms spread over the area now consisting of islands ; but 

 this must have been at a comparatively remote period in geological 

 time, and not at that recent date when the fabulous continent of 

 Atlantis included them all in its expanse, as believed by Forbes and 

 Wollaston. It is difficult to judge whether the insect fauna of 

 St. Helena will offer such reliable data for discussions of this 

 character as those of the more northerly Atlantic islands. As far 

 as it is at present known, it comprises many forms not found else- 

 where, amongst which is the large and remarkable Carabideous 

 beetle Haplothorax Burchellii, and several genera of small Cur- 

 culionidffi. It is not impossible that some of the smaller species 

 may yet be found in the more arid parts of South- Western Africa, 

 where the minute Coleoptera have not yet been well collected, but 

 so conspicuous a creature as the Haplothorax cannot be assumed to 

 have been overlooked, and this genus alone would be almost suffi- 

 cient to warrant the conclusion that St. Helena has an endemic 

 fauna, as peculiar as the flora it possessed before its native vegeta- 

 tion was destroyed. Mr. Melliss, I am glad to say, intends to 

 continue his entomological investigation of the island, as yet barely 

 commenced by him, and we may hope to hear yet of many curious 

 discoveries. 



