80 NORTHERN TIT. 



named it successively lugtibris, alpestris, and borealis, leaving it always 

 doubtful whether there were not two distinct species met with in 

 Scandinavia; it was described by Wallengren under the name of 

 ruticeti; being at Saleve, near Geneva, in June, 1844, it was placed 

 by M. G. Fatio under the name of alpestris, in a group of Grey Tits, 

 with P. sibiricus, lugubris, palustris, borealis, and atricapittus . M. De 

 Selys has described it quite lately as coming from the Grisons under 

 the name of its first describer as Partes Baldenstinii. 



"I have myself studied these' Tits in our Alps, and I have arrived 

 at the firm conviction that the alpestris is not only a particular form 

 of borealis, but that it possesses besides sufficient distinct characters to 

 separate it specifically from palustris. Having followed this Tit from 

 the plains to the limits of vegetation, I can speak from my own expe- 

 rience, as I went higher on the mountains, that there was first a 

 sudden passage from palustris to alpestris, and then a continued and 

 gradual transition of this last to the perfect borealis. The more 

 borealis inhabits the elevated parts of the Alps, the more its form and 

 colour of its plumage approaches those of the borealis of the north, 

 and vice versa, the lower it is found the more it loses the characters 

 given to it in more rigorous climates." 



M. Fatio then gives some interesting tables of measurements, and 

 afterwards discusses the question of climatic variety, which he does 

 not think can be maintained. 



" If it is the climate which causes the distinction between the borealis 

 of the north and that of our Alps, one might suppose that the palustris 

 is only a form of borealis, which, if submitted to other conditions, 

 might also have other characteristics; for why should we not have 

 slight transitions from one to the other, with a continual increase of 

 altitude and latitude. Let us compare the notable and parallel differ- 

 ences which distinguish the two plumages of alpestris and borealis 

 to the slight difference which palustris shows in its moulting, and we 

 should attach a great importance to this simple fact, not only as a 

 means of bringing together and identifying these two first Tits, but 

 also to separate them specifically from the last. Alpestris, of which 

 the habitat is near that of palustris, does not retire like it in autumn 

 into the plain to pass the winter; being able, like borealis, to resist 

 frost, it remains with it in the mountains, but it also, like borealis, 

 develops in its autumn moulting larger silky and different coloured 

 feathers, which, while they protect it from the cold, serve also to dis- 

 tinguish it always from palustris.'''' 



M. Fatio having made out a case of specific distinction for Parus 

 borealis, equally proves that P. alpestris is merely a variety, and 



