THE GLACIAL RANGE CONTRACTION, ETC. 73 



British resident species. For in the Italian peninsula 

 and on some of the various islands of the West Medi- 

 terranean — which during- the Glacial Epoch were not 

 islands at all, as a glance at the map of this Refuge 

 Area will show — there are other local species or races. 

 None of these islands arc yet thoroughly explored, and 

 probably other forms still remain to be discovered. As 

 may naturally be expected, the representative species or 

 forms in this area are neither numerous nor striking, 

 due partly to the enormous amount of migration taking 

 place over that area, which tends to check segregation 

 by the intermixing of individuals, and to its far less 

 complete isolation from continental Europe. The most 

 characteristic instance known to me is the island form 

 of the Nuthatch {^Sitta cccsia), confined so far as has yet 

 been ascertained to Corsica, and known as Sitta ivJiite- 

 Jieadi. A second instance is Passer italicc, the Corsican 

 and Italian representative of the Common Sparrow 

 {Passer doincsticus). 



In a considerable number of the instances tabulated 

 above there can be little if any doubt that the southern 

 races or species are the oldest, the parent races, the 

 northern forms being of more recent segregation, because 

 the young in first plumage of the latter resemble the 

 adults of the former — recapitulate in this portion of the 

 course of their development the stages through which 

 the species has passed in its evolution. I have been 

 unable to get the requisite particulars in some cases, but 

 in the following instances confirmation of the fact is 

 forthcoming. 



