AQUATIC COLEOPTERA OF THE OUTER HEBRIDES 63 



Harris, but I never found it in any abundance. Agabus 

 arcticiis, like D. griseostriatus, occurred at quite low levels 

 in the island, though it was certainly commoner in the 

 mountains, and, as in Eigg and Skye, it is almost confined 

 to the lochs and absent from the pools. 



In a recent paper,^ Dr Sharp pointed out that two species 

 had been passing under the name of Gyrinus opacus of 

 Sahlberg, and that the majority of the Britannic records 

 probably were not for Sahlberg's species, which is decidedly 

 northern in its range. In Harris the true opaais occurred 

 quite commonly on several of the small lochans and large 

 peat-holes above 750 ft., and was always associated with 

 D. griseostriatus and A. arc tic its. 



The following list includes all the species so far recorded 

 for the Outer Hebrides, and I have given in each case the 

 percentage to the nearest whole number of the actual number 

 of occurrences of each species taken by me, and have added 

 occasional notes. One unfamiliar name occurs in the list : 

 PhiUiydrus fuscipennis, Thoms. I have for some time 

 separated out two distinct species which had been passing 

 under the name of Ph. melanocep/ialus, Ol., and in looking 

 through the Tiree water-beetles which Mr Donisthorpe 

 kindly sent for my inspection in July 191 2, I named one 

 specimen as Ph. fuscipennis. In the paper on the collection 

 written by Mr W. E. Sharp,- I see that the only species of 

 the genus mentioned is Ph. nigricans, Zett., which, I venture 

 to think, is really Thomson's species ! Ph. nigricans has 

 otherwise not occurred in any western districts north of 

 Kirkcudbright, and the only Scottish records are for that 

 county, Dumfries, Berwick, Edinburgh, Fife, Forfar, and 

 Perth N. With the exception of Berwick, I have either taken 

 it myself in or seen specimens from all these divisions. Dr 

 Sharp in a recent paper ^ has also split up Ph. inelanocephalus 

 into two species: — 



1 "The British Species of Gyrinus," EnL Mo. Mag., Ser. 2, xxv., pp. 

 128-138, June 1914. 



- "The Coleopterist in Tiree," Eiit. Rec., 1913, pp. 19-23. 

 •' " Notes on British Philydrus," Enf. Mo. Mag., June 1914. 



