348 TOTANUS. 



distinctly barred, so that we may fairly assiime that T. incams, the adults of which have 



the under tail-covcrts very distinctly barred, is the older form — a conclusion supported by 



the fact that the scales at the back of the tarsus of the American form are constructed on a 



more archaic type than in the Siberian species. T. iticanus and T. semipalmatus are so 



Atlantic and different that we may recognize their subgeneric distinction by supposing that T. semi- 



raeitio palmatus emigrated along the Atlantic coast of America, and T. incanus along the Pacific 



America. ^oast of that continent. During the warm period which followed the Post-Pliocene Glacial 



Period the latter species appears to have sent a detachment across Behring Straits to East 



Siberia, the descendants of which have become partially differentiated, and are now known 



as T. incanus brevipes. 



Across Eartram's Sandpiper {T. barframi), like the Ruff in the Old World, appears to have 



America'" emigrated across country in the New World, and to have become almost entirely an inland 



species. 

 Pacifio coast The evidence that the ancestors of the remaining eight species emigrated along the 



Pacific coast of Asia is very strong. Four of them are Nearctic and four Palsearctic; of 

 the latter, one is absent from Western Europe, and the other three are represented by such 

 close alUes in the New World that it is reasonable to suppose that the American species 

 are the result of emigrations across Behring Straits during the Post-Glacial warm period. 

 These eight species are : — 



Old World. New World. 



T. terekius. 



T. hypoleucus. T. macularius. 

 T. ochropus. T. solitarius. 

 T. glareola. T. flavipes. 

 T. melanoleucus. 



The remarkable fact that T. melanoleucus almost exactly resembles in almost every 

 dimension T. glottis suggests the possibility that the former may be the American analogue 

 of the latter (though it has lost its white lower back and rump) rather than a giant form 

 of T. flavipes, which it almost exactly resembles in colour. The fact that the young in 

 first plumage of T. macularius so closely resembles the adult of its Palgearctic analogue, is 

 strong evidence that the latter is the older form. 



T. ochropus being the commonest of the four in India, was probably differentiated in 

 that country. The extraordinary abundance of T. glareola in Ceylon suggests that island 

 as the birthplace of that species. T. hypoleucus being the most abundant of the four in 

 Burma was probably isolated in that peninsula ; whilst the range of T. terekius bein^ the 

 least westerly, the Malay Archipelago may have been the original home of that species. 



