NATURAL HISTORY SOCIETY OF GLASGOW. 127 



Handa as compared with some other bird-stations on our coasts. 

 I have on many occasions counted the Guillemots occupying a 

 ledge, and generally found that the average of bridled birds on 

 Handa was one to ten, or twelve, of the common race. The 

 estimate of their numbers on this island, as given by Mr J. 

 Wolley, also agrees with my estimate. He writes (" Zoologist," 

 1852, p. 3478) that he spent four days there, and went 

 down on a rope " in every part of the rocks," and, after careful 

 examination, sums up by saying, "and in every row of ten or 

 twenty Guillemots, one or two were seen to have the white above 

 the eyes." 



Mr Wolley did not consider U. troile and U. ringvia as separate 

 species, nor did he recognise any difference in their eggs. Capt. 

 H. J. Elwes procured eggs of U. ringvia in the Hebrides, taken 

 from under the birds in 1868, and says of them, "more were 

 marked with streaks than blotches." My own experience of 

 them, in the same locality in 1870, is that they are quite un- 

 distinguishable from typical eggs of U. troile. 



In the Hebrides in 1870 Capt. H. W. Feilden and myself saw 

 bridled and common birds in copula, thus putting their identity 

 beyond a doubt. We also very carefully came to the conclusion 

 that the average of the bridled birds there was one to five of the 

 commoner race.* 



In his "Birds of the West of Scotland" (p. 426), Mr Robert 

 Gray gives the numbers of the bridled birds amongst the 

 Guillemot population of Handa as one in a hundred ; but this is 

 such a very low estimate indeed, that it is probably a printer's 

 error. My estimate of the numbers there has always been as 

 above stated. 



BLACK GUILLEMOT. 



URIA GRYLLE {Linnaeus). 



This bird is now very rare in Handa, though at one time, as we 

 were assured by the cragsmen, it was plentiful. The reason 



* I am not aware that any Guillemots have ever been found to partake of 

 the characteristics of hoth U. ringvia and U. troile, as would be the case in a 

 true cross formed by the interbreeding of species. All specimens hitherto 

 obtained have been either purely the one or purely the other, thus, as I 

 understand, proving their identity as a species, and giving an instance of 

 Darwin's dimorphism. 



