17 4 Proceedings of the Royal Irish Academy. 



In accordance with the spirit of the Clare Island Survey it is expected 

 that something should be said in this paper as to the origin of the Mammal- ■ 

 fauna and its age on the island. An attempt has here been made to do so ; 

 but it must be regarded as merely of a provisional nature. The serious 

 problems of the British fauna are now in commencement of being worked 

 out, and our ultimate view must depend on the results of investigations still 

 in progress. Further, these remarks must be regarded as based purely on 

 zoological data and without regard to geological conditions, other than as 

 required by a zoologist. I merely place on paper the geological conditions 

 which I conceive necessary in order to explain our Mammal-fauna. It is for 

 geologists to say if such conditions are possible. 



Summarizing the above list, it will be seen that the island claims a fauna 

 of ten species, which may be arranged as follows : — 



One volant species : — an unidentified Bat. 

 One aquatic species : — Otter. 

 Two marine species : — Grey and Common Seal. 



Three introduced terrestrial species : — Babbit, Irish Hare, Brown Rat. 

 One probably introduced terrestrial species : — House Mouse. 

 Two terrestrial species not known to have been introduced : — Pygmy Shrew 

 and Wood Mouse. Total, 10. 



For the purposes of the present inquiry all the species, except the two 

 last, may be neglected, since the aquatic and marine mammals are, apart from 

 the influence of man, found everywhere on the neighbouring coasts, and are 

 not known to differ from the forms inhabiting Great Britain and continental 

 Europe. 



The Pygmy Shrew and Wood Mouse are the only small mammals 

 undoubtedly native to Ireland, so that if any other small mammals were 

 present, they could only be of a species not represented in the Irish, 

 perhaps not even in the British fauna. There is no trace of any larger 

 member of the Irish Mammal-fauna having ever been found on Clare 

 Island. If any species was so, it has been exterminated and has left no 

 trace behind it. 



The Pygmy Shrew and the Wood Mouse are exactly the species which 

 one would expect to find on a small islet, since they are probably the most 

 widely distributed of the smaller British mammals. 



The Pygmy Shrew is found on Bathlin and Achill, and is the only 

 shrew of the Orkneys, Outer Hebrides, Isle of Man, and Lundy Island. 

 In the Inner Hebrides it is accompanied by the Common Shrew, and it is 

 present also on Anglesey, the Isle of Wight, and the Scilly Islands. 



