P alias's Sand- Grouse in 1863. 217 



dissected, I am sure that most of the examples killed in May 

 and June, both males and females, were in a condition to breed 

 very shortly. The birds obtained later in the year, so far as I have 

 observed, had successfidly progressed in or had accomplished 

 their moulting ; and this is an additional testimony in favour of 

 their well-doing in Europe. The beauty of the autumnal speci- 

 mens, in their new apparel, far surpassed that of the earlier ones. 

 And now to indulge myself in a few speculations on what 

 may have brought about this irruption of which I have just 

 given some of the details. I have conversed and corresponded 

 with many of my ornithological brethren on the subject, and 

 I have heard many ingenious suggestions respecting it, but, I 

 must say, without meeting with a satisfactory solution of the 

 difficulty. I commenced by observing, that in the records of 

 ornithology it is an unparalleled event ; the nearest approach to 

 it, that I am aware of, is the extraordinary visitation of Amp e lis 

 yari-ulus to the valley of the Muonio River, in 1858, which I 

 before mentioned in this journal (Ibis, 1861, p. 100). Yet that . 

 fell far short of this irruption, inasmuch as the distance traversed 

 by the wanderers was probably very much less. The influx of the 

 same bird, the Waxwing,into England in the winter of 1849-50, 

 and the great band of Nucifraga caryocatades which, in the 

 autumn of 1844, pervaded AVestern and Central Europe, im- 

 portant though they be, are events which were, probably, simply 

 the results of the ordinary migi'atory impulse turned in a new 

 direction, and in their efi'ects not comparable to the movement 

 of which I have here endeavoured to compile an account; for in 

 neither case was the migration attended with a real increase of 

 the breeding-range of the species. In the first place it is only 

 right that I should place before my readers some of the various 

 reasons which have been suggested to account for the pre- 

 sent occurrence. Dr. de Montessus considers that the Syr- 

 rhaptes was driven from its proper home " par quelque com- 

 motion atmospherique" (Rev. Zool. 1863, p. 393), and that, 

 without doubt, some " revolution extraordinaire dans la nature 

 bouleversee de sa patrie a determine une perturbation terrible 

 dans ^essence de ce petit etre^' {op. cit. p. 394) ; but I confess 

 myself at a loss to imagine of what nature this atmospherical 



VOL. IV. Q 



