CHAPTER XVI 



CONTINENTAL ISLANDS OF EECENT ORIGIN : GREAT 

 BRITAIN 



Characteristic Features of Recent Continental Islands — Recent Physical 

 Changes of the British Isles — Proofs of Former Elevation — Submerged 

 Forests — Buried River Channels — Time of Last Union with the Conti- 

 nent — Why Britain is poor in Species — Peculiar British Birds — Fresh- 

 water Fishes — Cause of Great Speciality in Fishes — Peculiar British 

 Insects — Lepidoptera Confined to the British Isles — Peculiarities of the 

 Isle of Man — Lepidoptera — Coleoptera confined to the British Isles — 

 Trichoptera Peculiar to the British Isles — Land and Freshwater Shells 

 — Peculiarities of the British Flora — Peculiarities of the Irish Flora — 

 Peculiar British Mosses and Hepaticse — Concluding Remarks on the 

 Peculiarities of the British Fauna and Flora. 



We now proceed to examine those islands which are the 

 very reverse of the " oceanic " class, being fragments of 

 continents or of larger islands from which they have been 

 separated by subsidence of the intervening land at a period 

 which, geologically, must be considered recent. Such 

 islands are always still connected with their parent land by 

 a shallow sea, usually indeed not exceeding a hundred 

 fathoms deep ; they always possess mammalia and reptiles 

 either wholly or in large proportion identical with those of 

 the mainland ; while their entire flora and fauna is 

 characterised either by the total absence or comparative 

 scarcity of those endemic or peculiar species and genera 

 which are so striking a feature of almost all oceanic 

 islands. Such islands will, of course, differ from each 



