TOTANUS. 



347 



The geographical distribution of the species included in the genus Totanus presents Emigration. 

 some difficulties, but on the whole it confirms the theory of a general dispersal of a 

 circumpolar species by a Glacial Epoch. These birds are possessed of such powerful organs 

 of flight that they have most of them extended their winter as well as their summer ranges 

 from ocean to ocean. 



The five species which have white lower backs must be regarded as the typical group Atlantic 

 of the genus Totanus. They appear to represent the party which emigrated from the Europe 

 Polar Basin along the Atlantic coast of the Old World. None of them are found in the 

 New World except as accidental visitors, and they are the only group represented in 

 Iceland and the Faroes. We may assume that they were subgenerically differentiated 

 during the period of their isolation, whilst the gradual increase of the Arctic ice drove them 

 south, and that they rapidly spread eastwards along the shores of the Mediterranean to the 

 southern coast of Asia, and that during the height of the Post-Pliocene Glacial Epoch they 

 were differentiated into species in their present most favoured winter-quarters, whence they 

 again spread over most of the Palsearctic Kegion during the warm period which followed. 

 It is perhaps impossible accurately to determine the exact area of isolation of each species, 

 but we are by no means without circumstantial evidence of the facts of the case. 



To begin with the East, we may assign the Malay Peninsula to Erman's Sandpiper 

 {T. ffuttiferus), as it appears to be still confined to that district in winter. India may lay 

 claim to have been the native country of the Greenshank {T. glottis) ; and Ceylon to the 

 small, and on that account probably island, form which we call the Marsh-Sandpiper 

 (?'. stagnatilis), and which Legge describes as " the most abundant of its genus " in that 

 island. The Redshank {T. calidris) was most likely isolated in West Africa ; whilst the 

 Dusky Redshank {T.fuscus),\k& most Arctic species of the genus, appears to have remained 

 furthest north on the shores of the sea which is now cut up into the Levant, the Black 

 Sea, the Caspian, the Persian Gulf, and the Red Sea. 



The Ruff {T. pugnax) must also be regarded as having had a West Palsarctic origin, Across 

 as it appears to be only an accidental visitor to the Pacific shores. It is perhaps less a Eurasia. 

 shore-bird in its habits than the five species already discussed ; it may fairly claim to have 

 become subgenerically difierentiated from them ; and the remarkable extent to which 

 sexual selection appears to have modified its nuptial plumage suggests the idea that it 

 represents a body of Sandpipers which were isolated from their companions at an early 

 date, and emigrated south across country. There seems reason to believe that at the 

 height of the Glacial Period these birds found refuge in the valley of the Nile, where they 

 are now extremely abundant in winter. 



The nearest allies of these species are probably the two or three which have plain 

 brown axillaries— r. semipalmatus, T. incanus, and T. brevipcs. This little group ranges 

 across East Siberia and North America. The specific distinctness of the two latter is 

 doubtful, and for that very reason it gives us a clae as to which is the least-changed form. 

 Birds of the year of the Siberian form [T. brevipes) have the under tail-coverts more or less 



2t2 



