CHAEADEIUS. 



117 



to add two more characters. Axillaries white, efifectually excludes C. morinellus, C. veredus, 

 and C. australis ; whilst belly white, excludes C. totajiirostris at all ages and seasons. 



The Ringed Plovers appear to be a well-characterized group, though their characters 

 are all dependent upon colour or pattern of colour, and cannot be regarded as structural, 

 at least so far as they are known. These birds may be described as follows : — 



A dark ring passes round the neck — black in males in breeding-dress ; brown in males 

 in winter-dress, in females at all seasons, and in birds of the year of both sexes. Above 

 this dark ring is generally a white ring, but this is in one species confined to a white 

 collar at the back of the neck, and in another species both collars are absent. The legs 

 and feet are always pale, and the base of the bill is generally pale. The hind toe is always 

 absent. The two centre tail-feathers are brown at the base, nearly black towards the end, 

 with a spot of white at the extreme tip ; each succeeding feather has a longer white tip, 

 and is paler at the base, until the outer web of the outer feather is pure white, but otherwise 

 the black subterminal band is very conspicuous. The axillaries are always white, as is also 

 the belly. 



They may be subdivided into two groups, one of which has white at the base of the 

 outer webs of the innermost primaries, whilst the other has no white on the outer webs of 

 the primaries. The former may be diagnosed as follows : — 



Subgeneric group Hiaticulce typiccje, primariorum interiorum pogoniis externis pro 

 magna parte albis. 



The latter may be diagnosed as : — 



Subgeneric group Hiaticulce minores, primariorum interiorum pogoniis externis 

 omnino brunneis. 



Of the first group G. hiaticiila may be regarded as the type. They seem to have 

 escaped from the Polar Basin along the Atlantic coast of America. C. semipahiiatus returned 

 to the north when the Glacial Period was over, and subsequently spread westwards to 

 Alaska, having been isolated in Central America, whilst C. melodus was probably isolated 

 in the West Indies. C. hiaticula seems to have crossed over by way of Iceland from 

 Greenland, and to have subsequently spread eastwards as far as the valley of the Yenesay. 

 It was probably isolated in Africa, where it still winters, and whence emigrating parties 

 crossed over to Australia and subsequently to New Zealand, becoming respectively 

 C. monachus and C. novce-zelandice, their greatly changed conditions of life favouring rapid 

 differentiation. C. vociferus may have been differentiated in the valley of the Amazon, 

 whence a colony crossed over to West Africa and intermarried with some of the ancestors 

 of C. minor, as hereinafter suggested. 



Of the second group C. minor may be regarded as the type. They appear to represent 

 the Plovers which escaped from the Polar Basin up the great Asiatic rivers, and they are 

 for the most part river and lake Plovers rather than shore birds. 



During the Glacial Period they seem to have been differentiated into four species : 

 C. tricollaris and its post-glacial alhes C. forhesi and C. bifrontatus were isolated in 



Other 

 characters. 



Hiaticulae 

 typicEe. 



HiaticulEB 

 minores. 



Emigra- 

 tions. 



