HIMAXTOPUS. 



275 



all four parties of emigrants have left descendants, and to determine by what characters 

 they may now be detected. The four groups of which we are in search are Stilts, Semi- 

 Stilts, Avocets, and Semi-Avocets. The last three species on the list, H. avocetta, 

 H. rubricollis, and H. americanus, are unquestionably thorough-bred Avocets, diagnosed as 

 mantle white, scapulars and secondaries for the most part white; the first six, H. mewicanus, 

 H. hmdseni, H. brasiliensis, H. leucocephalus, H, melas, and H. melanopterus, are as 

 unquestionably thorough-bred Stilts, having all the parts mentioned above black instead 

 of white. These are the important characters which date farthest back ■ but it is worthy 

 of note that in these two groups the black mantle &c. is correlated with a straight 

 bill, very slightly webbed feet, and the absence of a hind toe ; whilst the white mantle 

 is correlated with a recurved bill, strongly webbed feet, and the presence of a hind toe. 

 We have now two species left, H. andinus and H. pectoralis. The former is called an 

 Avocet, and the latter a Stilt, by the writers who place an extravagant value on structural 

 characters. In ray opinion H. andinus is a model representative of a Semi-Stilt. It has 

 the black mantle and wings of the Stilts, whilst its strain of Avocet blood crops up in the 

 less important characters of its recurved bill, webbed feet, and hind toe. II. pectoralis, on 

 the other hand, is an excellent Semi-Avocet, its white mantle and the white on its wings 

 proclaiming it an Avocet, whilst its straight bill and the absence of a hind toe show its 

 relationship to the Stilts. 



The third step in the argument is the apportioning of the four groups to the four 

 routes. The case is a very simple one. The Semi-Stilt and the Semi-Avocet are, by the 

 terms of the hypothesis, the representatives of the two Pacific-coast emigrations ; and as 

 the Semi-Stilt inhabits Peru, and the Semi-Avocet Australia, there can be no dispute that 

 the Semi-Stilts emigrated along the American shores of the Pacific, and the Semi-Avocets 

 along the Asiatic shores of that ocean. The Avocets consequently represent the Old- World 

 pair, the true Avocets migrating along the Atlantic coast. The Stilts being the New-World 

 couple, we must apportion the Atlantic coast of America to the true Stilts. 



The ancestors of the true Avocets seem to have left the Polar Basin by way of the 

 European shores of the Atlantic, and to have occupied Africa and the southern portion of 

 the Palsearctic Region. Finding the Oriental Region already occupied during the breeding- 

 season by the Stilts, they seem to have sent off a detachment to Australia. Here also 

 the ground appears to have been partially occupied by congeneric species, so that a second 

 emigration became necessary, which found a home on the west coast of the United 

 States. The true Stilts are so closely related to each other that the precise order of 

 their emigration is not very easy to determine, but we may begin by assuming that 

 they left the Polar Basin along the Atlantic shores of America; thence they seem to 

 have crossed the tropics to the Chilian subregion of South America and to the 

 Sandwich Islands. A second detachment appears to have crossed the Atlantic to the 

 Canary Islands and Spain, whence they spread eastwards up the Mediterranean to the 

 Oriental Region and across the Ethiopian Region. Meanwhile the restricted area of the 



2n2 



Divide into 

 four parties. 



Routes of 

 the Semi- 

 Stilts and 

 Semi- 

 Avocets. 



Route of the 

 Avoeets. 



Route of the 

 Stilts. 



