GEOGRAPHICAL DISTRIBUTION 339 



as no indication of loss of wing-power, which is one of the effects of 

 protracted isolation, has been observed among them, though, as is 

 well known, many of the Insects are said to shew it remarkably. 

 Moreover, the colonization seems to be going on still, and it happens 

 not unfrequently that when an island has a well-established local 

 race it is yet more or less regularly visited by individuals of the 

 normal and parental form. 



The European Province does not seem to possess a single genus 

 that can be accounted peculiar to it, but it has one consisting of a 

 single species, Mergulus alle (Rotche), which does not elsewhere 

 occur in the Palsearctic Subregion, though it inhabits the northern 

 parts of the Canadian Province of the Nearctic. It would, how- 

 ever, extend too far for the present article to dwell upon more 

 than a very few of the curiosities of distribution revealed by the 

 continued observation of birds in Europe. There is no need to 

 travel out of our own island to meet Math some of the most 

 remarkable among them, and we may take the case of the Night- 

 ingale as an example. In England the western limit of this 

 incomparable songster's range seems to be formed by the valley of 

 the Exe, which is only overstepped on rare occasions. But even 

 in the east of Devon it is local and rare, as it also is in the north 

 of Somerset, though plentiful in other parts of that county. Cross- 

 ing the Bristol Channel, it is said to be not uncommon at times 

 near Cowbridge in Gllamorganshire ; but this seems to be an isolated 

 spot, or at any rate there is no evidence of its being found else- 

 where in Wales, or between that place and Tintern on the Wye, 

 where it has been reported to be plentiful. Thence there is more 

 or less good testimony of its occurrence in Herefordshire, Shrop- 

 shire, Staffordshire, Derbyshire, and so on, to about 5 miles 

 north of York, but not further, that is to say in the ordinary 

 course of things, for Mr. Wolley-Dod, an unquestionable authority, 

 recorded one that he heard singing at Malpas in Cheshire in May 

 1889.^ Along the line thus sketched out, and immediately to the 

 south and east of it, the appearance of the Nightingale, even if 

 regular, which may be doubted, is rare, and the bird is very local ; 

 but in many parts of the midland, eastern, and southern counties 

 it is abundant, and the woods, coppices, and gardens ring with that 

 thrilling song which has been the theme of writers in all ages. 

 There are many assertions of its occurrence in England further to 

 the northward, but some of them rest on anonymous authority 

 only, and all must be regarded with the greatest suspicion. Still 

 more open to doubt are the statements which have been made as 

 to its visits to Scotland, while in Ireland there is no pretence even 

 of its appearance. No reasonable mode of accounting for the 



^ Others were reported to have been heard about the same time in Flintshire 

 and near Rhyl. 



