150 ANNALS OF SCOTTISH NATURAL HISTORY 



As the fauna and flora of these western islands are of 

 extreme interest in connection with the question of the origin 

 of the Britannic l fauna and flora, I took the opportunity of 

 spending a week in the district during last September, 

 staying a few days at Broadford in Skye, and a few days 

 on the island of Eigg. 



Neither of these islands presents much variety of habitat, 

 peat-moss and stream being practically the only kinds of 

 collecting ground. In Skye, I spent my time on the ground 

 immediately around Broadford, chiefly on the peat-mosses 

 between Ben Suardal and the road from Broadford to Loch- 

 na-Dal and Isle of Ornsay. My chief object was to discover 

 as much as possible of the ' Arctic ' group of water-beetles of 

 which Deroncctes griseo-siriatus, Dytiscus lapponicus, Hydro- 

 porus nwrio, tristis, and nielanarhts, Agabus arcticus and 

 congener^ and Ilybius cenescens are examples. Several of 

 these species have an extensive range in the British Islands, 

 but the first two are limited to highland lochs in Scotland 

 and Ireland, 2 and, so far as is at present known, they show 

 a decidedly discontinuous distribution. I was therefore 

 specially anxious to know what their associates were, and 

 kind of habitat they survive in. 



Those who have taken D. lapponicus in the British 

 Islands have favoured us with fairly minute descriptions of 

 habitat and other details. I have less than a dozen refer- 

 ences to the capture of this species, but in every case where 

 sex is mentioned the scarcity of the female is remarked upon. 

 Somerville (1867) mentions that he took 45 specimens in 

 Mull, and " with very few exceptions all were males." 

 Buchanan White (1870) remarks on the scarcity of females 

 in Mull and in Strathglass (East Inverness) ; in this latter 

 locality out of 12 or 14 specimens only 3 were females. 

 J. J. King (1897) also remarks that in Mull he found the 

 females much scarcer than the males. 



In every case where details of the habitat are mentioned, 

 the absence of fish and the presence of newts is remarked 



1 The term "Britannic" includes all the British Islands. Vide G. H. 

 Carpenter and W. Evans, " Proc. Roy. Phys. Soc. Edin.' 5 xv. 219(1904); or 

 G. H. Carpenter, "Irish Nat." xv. 13 (1906). 



2 For Deronectes griseo-striattis in Ireland, -vide. "Irish Naturalist," Sept. 

 1910, p. 183. 



