TEOGLODTTES. 97 



for solution which are not unfrequently met with in ornithology, and in dealing with 

 which no method of nomenclature has yet proved altogether satisfactory. Before 

 treating the Central- American races separately, it will be convenient here to view the 

 relationship of all the forms collectively. 



Throughout the two continents of America and some of the adjacent islands (the Antilles 

 alone excepted). Wrens of the Troglodytes aedon group are found. These seem at once to 

 be tolerably sharply divisible into two species: — T. aecZora of North America, which also 

 occurs in Mexico ; and a southern form, subject to great local variation, which spreads 

 from Mexico over the whole South- American continent to Cape Horn. Of T. aedon three 

 races have been set up, none of which do we think can be maintained, for reasons stated 

 below. Of the southern form, T. insularis of the island of Socorro seems fairly separable ; 

 and on the mainland the following names have been proposed : — T. iniermedius for the 

 Central- American bird, which ranges from Southern Mexico to Costa Eica ; T. inquietus 

 for the Panama bird; T. striatulus for the Bogota bird; T. tessellatus for that of 

 Western Peru. The Guiana bird is T. furms, the Brazilian T. wquinoctialis* ; the 

 bird of the extreme south is T. magellanicm f, and the Chilian T. hornensis J. It is 

 with all these local forms that our great difficulty lies. Characters which in some 

 places seem definite, gradually disappear on the confines of the range of what at 

 first sight is an apparently distinct form ; so that it would seem that no diagnostic 

 features exist by which to separate all these various races. 



The Central-American T. intermedius perhaps comes nearest the South-Brazihan 

 bird, difiFering in being rather more deeply coloured below, in having the crissum (in 

 the adult bird) more strongly banded, and in the tail being shorter. The Panama 

 Wren passes southwards through Colombia to Peru, no tangible difference being 

 evident between T. inquietus and T. tessellatus. The typical bird of this race is dis- 

 tinguished by the pale colour of its under surface, the flanks alone being tinged with 

 rufous, and by its having the feathers of the back more or less strongly barred across 

 with fine blackish bands. These characters are also present in the Guiana T.furvus, 

 though the upper plumage is a shade more rufous and the markings of the back less 

 distinct. Examples from the island of Tobago and others from the vicinity of Bogota 

 in Colombia are not separable ; but m Trinidad and Venezuela specimens seem to be of 

 a deeper rufous above, and the dorsal marks are obsolete. This latter form passes to 

 Santa Marta, to the Amazons, Ecuador, and to the vicinity of Lima in Peru. Thus no 

 definite boundaries, in accordance with the generally recognized rules of the distri- 

 bution of South- American birds, can be set to these variable birds ; and, failing them, 

 the only course open to us is to call them all Troglodytes furvus as a comprehensive 

 name, including the true T. furvus of Guiana, and the aberrant T. tessellatus of 

 Western America, from Panama to Peru. The bird of South-eastern Brazil has a 

 * Sw. Om. Draw. t. 13. t Gould, P. Z. 8. 1836, p. 88. 



t Less. Joum. I'lnst. 1834, p. 316, et Navig. aut. d. Globe de ' La Thetis,' ii. p. 327. 



BIOL. CBNT.-AMBR., Zool., Aves, Vol. 1, April 1880. 13 



