Lanius excubitor and Lanius major. 39 



Thougli, as yet, we are far from having obtained exhaustive 

 observations, it would seem a fact that throughout the Eastern 

 Arctic region the inner spot is wholly or in part suppressed 

 oftener than is the case in the southern districts. This 

 characteristic tendency increases with the distance east ; in 

 Eastern Asia the transition is probably impercej^tible to the 

 form which, under the name of L. borealis, we know from 

 North America"^ (an exceptional approximation to this form 

 occurs even in Western or Central Europe). In like manner 

 does the transition proceed to other forms in which the white 

 colour predominates, viz., throughout Southern Europe^ 

 North Africa, and East Asia. 



Hence we must infer that L. excubitor (like L. ludovi- 

 cianus, and other species of the same genus, if in a less 

 degree) has a remarkable tendency to variation, more espe- 

 cially as regards the extent of the white colour on the tail- 

 feathers and on the bases of the secondaries, as also in the 

 development of the vermiculatious across the abdomen. This 

 variation occurs in some cases quite individually, in others 

 more constantly, a definite kind of variation being exhibited 

 with greater and greater frequency according as the distance 

 from the region constituting the habitat of the typical 

 form increases, till a number of more or less constant 

 races, known to us under various names, at length are 

 produced. 



To enumerate all these varieties, or '^ species,^^ derived 

 from L. excubitor, does not come within the object of the 

 present paper. In conclusion, I shall merely enumerate such 

 of the forms as are found with greatest frequency in the 

 tracts of the Palsearctic Region. 



1. The tyj)ical form (L. excubitor, forma excubitor), with 

 its fully and normally developed inner spot on the secon- 

 daries, inhabits chiefly Central and Western Europe, and 

 produces normally young which, even in the nesting- plumage, 

 exhibit this mark in full development, as in the old birds. 



* "My immature bird from the Amoor is undistinguishable from 

 L. borealis, VieUl., but I have seen au almost complete series from it 

 to L. excubitor" (Seebohm, Ibis, 1880, p. 115). 



