Notes on some Waders. 531 



form must therefore be called Charudrius collaris yracUis, 

 and the synonymy of the two forms is as follows : — 



1. Charadrius collaris collaris Vieill. 



Charudrius collaris VieiJlot, Nouv. Diet. d'Hist. Nat. 

 xxvii. p. 136 (1817 — Based on the " Mbatuitui collar negro ^' 

 of Azara from Paraguay). 



Charadrius azarai Teraminck, PI. Col. 184 (1823— based 

 ou the same bird, no. 392 of Azara from Paraguay). 



Charadrius larvatus Lesson, Man. d'Orn. ii. p. 318 (1828 

 — Brazil, Delalande coll.). 



The wing measures 102 (once 101) to 105 mm. 



This form inhabits southern South America from Ai'gen- 

 tina to Paraguay, also the province of Rio de Janeiro 

 (Marami)aya, batterer coll. in the British jNIuscum) and 

 the Rio Pilcomayo, and extends to Cosnipata in Peru. 



2. Charadrius collaris gracilis (Cab.). 



jEgialitis gracilis Cab;inis, Journ. f. Orn. 1872, p. 158 

 ( Tehuantepec). 



Wing: 87-.5-97 mm. 



Inhabits Central America and northern South America, 

 where the two forms appear to overlap, though further 

 evidence is required whether this takes place in the breeding- 

 season. There are, however, in the British Museum 

 specimens from as far south as Iquitos and Chamicuros in 

 Pern, and one from Cosnipata a{)pears also to belong to it, 

 others from Kio Grande do Sul in southern Brazil, and from 

 Matto Grosso. In the whole of north Brazil only the small 

 race occurs, as well as in Guiana. 



V. On Charadrius dubius. 

 As in the case of C. alexandrinus there are several races, 

 which cannot be overlooked, but they are closely allied and 

 obscured in collections by the northern migrants, which 

 often stray into the areas inhabited by their tropical allies. 

 While the former ones are mighty ^vanderers, the latter are 

 resident, as is evidently the case with C. alexandrinus., and 

 indeed most tropical birds. 



