208 



VANELLUS. 



Neotropical 

 species. 



Old-World 



tropical 



species. 



tiaies and in various places, and must have remained isolated from each other for a sufficient 

 length of time to have enabled them to become differentiated from each other so completely, 

 that when, from the gradual extension of the area of distribution of each species, some of 

 these areas impinged or overlapped, the various species had become so distinct that little or 

 no cross-breeding took place. 



The species which has the most arctic distribation is V. cristatus, which represents the 

 descendants of those Lapwings which hung on the outskirts of the glaciers, and never 

 emigrated to the tropics during the glacial epoch until towards its close, when a party 

 crossed the Atlantic to South America, and gradually spread over the Brazilian and Chilian 

 subregions. In so wide a range it is not remarkable that a partial differentiation 

 subsequently took place, the birds in the north becoming V. cayennensis, and those in the 

 south a larger race known as V. cayennensis chilensis. V. resplendens may be the result of 

 an eastern emigration across the Pacific to Peru, where it has found a Paleearctic climate 

 on the plateaus ten thousand feet above the sea. 



It is impossible to say how early V. gregarius became differentiated from its allies ; but 

 it seems to represent a more southerly group of species, which may have originated on that 

 part of the Kirghiz Steppes which lies west of the Ural Mountains, and extends across the 

 Caspian into Turkestan. During the intense struggle for existence caused by the glacial 

 epoch, parties from this colony seem to have emigrated into India (the ancestors of 

 V. ventralis), into Persia (the ancestors of V. leucurus), to the coast of East Africa (the 

 ancestors of V. crassirostris), and into Egypt (the ancestors of V. sjjinosus). The valley 

 of the Nile seems to have become an Eldorado for the Lapwings, and many parties of 

 emigrants seem to have ascended it, and to have found congenial homes in different parts 

 of the continent of Africa — the ancestors of V. inornatus in the West, those of K melano- 

 pterus in the East, those of V. coronatus in the South-west, and those of V. speciosus in 

 the South-east, whilst an adventurous party seem to have crossed the Atlantic to South 

 America, and to have become differentiated into V. cayanus. 



In order to simplify the Key to the species they are divided into two purely artificial 

 groups, those with a small hind toe and those without that appendage. There cannot be 

 any doubt that the presence of a hind toe or of a spur is a character of only secondary 

 importance in this genus. To subdivide the genus Vanellus on these lines is unscientific in 

 the extreme, inasmuch as it separates the most closely aUied species, associates together 

 distantly allied species, and consequently makes the study of their geographical distribution 

 impossible or misleading. Eor example, nothing can be more certain than the very close 

 relationship between V. cristatus, V. cayennensis, and V. resplendens. They are unques- 

 tionably more nearly related to each other than they are to any other species of the genus ; 

 nevertheless the first has a hind toe and no spur, the second both a hind toe and a spur, 

 whilst the third has a spur but no hind toe. Every species in the family of Charadriidse 

 appears to be gradually losing or to have recently lost its hind toe, probably by the action 

 of what Darwin has called the law of degradation by disuse, and it appears to be seldom a 

 feature of much genetic value wbrtlier [}\p hind toe has almost or quite disappeared. 



