98 TEOGLODTTIDiE. 



strong rufous tint beneath; this is more particularly evident in Bahia examples, 

 where the throat alone is whitish ; the crissum, too, of these birds is spotless. In Rio 

 examples the crissum has a few black marks ; and this form extends southwards to the 

 Argentine Eepublic and Patagonia. Nor does the ChiHan bird differ appreciably in 

 coloration ; but the tail seems to be always longer than in birds from the eastern side 

 of the continent. This character also fails to be of much service, as the length of the 

 tail is found to be gradually less as one proceeds northwards from Patagonia and Chili. 

 Of these southern birds, those from Bahia are most readily distinguishable at first sight 

 by their brighter rufous under surface and spotless crissum ; but the points of distinction 

 between Eio birds and others already referred to from Venezuela &c. are so insig- 

 nificant as to be hardly capable of recognition with certainty. But the Venezuela 

 bird passes into T. furvus of Guiana, and thence into T. tessellatus; so that the 

 passage between the extreme forms, the birds of Bahia and Peru, seems almost complete. 

 The geographical inter-relationship of the extremes and means is so complicated that 

 a reasonable explanation as to how the present state of things has come about has not 

 suggested itself to us. Still we see, in the apparent rapprochement of the Central- 

 American and Brazilian birds, an example of a law of distribution of which we now have 

 many examples. 



In treating of the forms of Troglodytes within our boundaries our difficulties as 

 regards their discrimination are much less. T. aedon and T. insularis are easily 

 defined ; and the relationship of T. intermedins to the Panama race of T. furvus, as we 

 are now constrained to call the bird of the southern continent, is not too close to 

 prevent their recognition. 



Altogether six species or races of Troglodytes are found within our borders, — one, 

 T. aedon, being the intrusion of a northern bird into Mexico ; another, T. furvus, the 

 extension of a southern form into the State of Panama ; a third, T. solstitialis, is a 

 bird of the Andes found in Costa Pica; two others are local modifications of the 

 southern T. fwvus ; and T. hrunneicollis a species without near allies. 



1. Troglodytes aedon. 



Troglodytes mdon, Vieill. Ois. Am. Sept. ii. p. 52, t. 107'; Baird, Eev. Am. B. i. p. 138=. 



Troglodytes parkmanii, Aud. Orn. Biogr. v. p. 310'; Baird, Eev. Am. B. i. p. 140*. 



Troglodytes adon, var. parkmanni, Baird, Brew. & Ridgw. N. Am. B. i. p. 153 '; Coues, Birds N W 



p. 32°. 

 Troglodytes domesticus parkmani, Coues, B. Col. Vail. i. p. 171' (ex Bartram). 

 Troglodytes americanus, Aud. Orn. Biogr. ii. p. 452 ^ 

 Troglodytes mdon, var. aztecus, Baird, Rev. Am. B. i. p. 139°. 

 Troglodytes aztecus, Sumichrast, Mem. Bost. Soc. N. H. i. p. 545 '". 



Supra nrarino-bninneTia, uropygio patQo rufescentiore ; dorso, alis et Cauda nigro transversim fasciatis ; subtus 

 gnseo-albidus fusco vix irroratua, hypochondriis et crisso leviter fusoo transfasciatis, rostri maxiUa 



