138 Mr. H. E. Dresser. 



Great Britain by Parus britannicus, and in north-west Africa 

 by Parus ledouci, and Parus ductus, which inhabits northern 

 Scandinavia, is represented in north Asia by a very closely 

 allied species, Parus grisescens. The Marsh Tits may fairly 

 be divided into several distinct forms, viz., Parus palustris, the 

 common continental and British Marsh Tit, which is replaced 

 in Scandinavia by a paler and slightly different form, Parus 

 borealis, which, again, in north Asia has the differences so 

 much intensified that it merges into Parus camtschatkensis, 

 but curiously enough in Japan we find a form so closely 

 assimilating with Partis palustris that it does not appear to me 

 to be fairly separable, though some authors treat of it as a 

 subspecies under the name of Parus palustris, or japonicus. 

 Our common Blue Titmouse, Parus cceruleus, under the 

 influence of the brighter skies of southern Europe, becomes 

 much more rich and bright in tone of colouration, but these 

 southern birds are not specifically separable. In north Africa 

 and on the Atlantic Islands, however, a permanently different, 

 much deeper coloured form occurs, which is separated under 

 the name of Parus teneriffce. 



The Nuthatches vary not a little in different portions of the 

 Palasarctic regions, some of the varieties not being sufficiently 

 pronounced to allow of specific distinction, whereas some are 

 referable to closely allied, though distinct species. The Wren 

 has a near ally, Trogloytes borealis, inhabiting the Foeroes 

 and Iceland, but the common Creeper, though subject to some 

 little climatic variation, is found right across into the Nearctic 

 region. 



Amongst the Wagtails the variations are extreme. In Europe 

 proper there are but two species of White Wagtails, Motacilla 

 lugubris the western form, and Motacilla alba the eastern 

 form ; but in Asia this latter has split up into several climatic 

 forms which have fully attained the rank of species. The 

 Yellow Wagtails, again, have branched out into several closely 

 allied species, as for instance M. flava, M. viridis, M. juelauo- 

 ■cephala and M. raii, and the same may be said of the Pipits. 



The Grey Shrikes present a peculiar instance of extreme 

 climatic variation. In Europe we have in northern and 

 central Europe Lanius excuhitor, in south western Europe 

 Lanius inerididionalis, in north western Africa Lanius 

 algerieusis, all differing sufficiently and constantly so that they 

 may fairly be looked on as distinct species ; and in south 

 eastern Europe we have a form of Lanius exctcbitor which is 

 fairly distinct, viz., Lanius lahtora, which ranges, subject to 

 some variation, far into Asia ; but in northern and central 

 Asia we find a number of forms of Lanius exctcbitor all 

 varying in colouration and in the amount of white on the 



