1907. Notes, 179 



greatly more varied than that of the British Islands, because it was con- 

 nected with the Asiatic continent in recent geological times. That 

 continent differed in Tertiary times from our own, in so far as it probably 

 covered a larger area than it does now, while Europe was an archipelago 

 of islands. An enormous and rapid development of the fauna took 

 place in Asia. In Europe the weak island faunas after their junction 

 were largely swept away by the incoming rush of the more highly 

 specialized Asiatic types. There was practically no exodus from Europe 

 to Asia. All our indigenous fauna could do was to struggle against the 

 newcomers. 



Mr. Moffat urges that the mere conversion of a piece of land into an 

 island does increase, to every species inhabiting that land, the chance of 

 becoming extinct. That seems to me a very sound argument, because, 

 as he remarks, any local devastation may totally exterminate a species in 

 an island, while on a continent the same species may re-enter the devas- 

 tated ground from other parts. Yet, as a matter of fact, palaeontology 

 clearly indicates that species may perish on a continent just as much as 

 on an island. I need only refer to the Irish Elk, the Mammoth, and 

 such like forms which had a wide range within recent geological times 

 and which have died out everywhere. Prof. Ray Lankaster suggests, in 

 his remarkable work on the " Kingdom of Man," that germ-carrying flies 

 may have been the cause of the extinction of some of the larger mammalia, 

 which have vanished from wide areas with such extraordinary rapidity. 

 Various causes, no doubt, acted together in bringing about these 

 changes in our fauna. 



Mr. Moffat's keen power of observation is well exemplified by the facts 

 he advances in favour of his supposition, that species may be limited in 

 their range by diminished fertility towards its outermost parts. If this 

 is a general law it ought to apply to Invertebrates as well as Vertebrates. 

 It is certainly worth testing in different countries, for it might explain 

 many anomalous features in the distribution of living organisms. And 

 yet how are we to harmonize this view with the apparent fact that on 

 an island the number of individuals in a given area is greater than on a 

 continent ? It has always struck me very forcibly when collecting Inver- 

 tebrates abroad that, while I secured a great many species during a day's 

 search, the number of individuals I noticed was small as compared with 

 that on an island. 



The perusal of Mr. Moffat's address has given me great pleasure. He 

 has raised so many interesting points founded upon personal observa- 

 tion, he has opened such a wide field for further studies, that I trust the 

 members of Naturalists' Field Clubs whom he specially appeals to, will aid 

 him in the accumulation of additional knowledge. The acquisition of 

 new knowledge will be an enjoyment to many, and a special help to 

 those who regard the Irish Naturalist as one of the best means in spread- 

 ing and advancing the study of Natural Science in Ireland. 



R. F. SCHARFF. 



Dublin Museum. 



