98 TROGLODYTIDZ. 
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 Republic and Patagonia. Nor does the Chilian 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 Rio birds and others already referred to from Venezuela &c. are so imsig- 
nificant as to be hardly capable of recognition with certainty. But the Venezuela 
bird passes into 7. furvus of Guiana, and thence into 7. 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. TZ. aedon and TL. insularis are easily 
defined; and the relationship of 7’. intermedius 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, 7. furvus, the 
extension of a southern form into the State of Panama; a third, 7. solstitialis, is a 
bird of the Andes found in Costa Rica; two others are local modifications of the 
southern 7. furvus; and 7. brunneicollis a species without near allies. 
1. Troglodytes aedon. 
Troglodytes edon, Vieill. Ois. Am. Sept. ii. p. 52, t. 107’; Baird, Rev. Am. B. i. p. 138”. 
Troglodytes parkmanii, Aud. Orn. Biogr. v. p. 310°; Baird, Rev. Am. B. i. p. 140°. 
Troglodytes edon, var. parkmanni, Baird, Brew. & Ridgw. N. Am. B. i. p. 153°; Coues, Birds N.W. 
p- 82°. 
Troglodytes domesticus parkmani, Coues, B. Col. Vall. i. p. 171" (ex Bartram). 
Troglodytes americanus, Aud. Orn. Biogr. ii. p. 452°. 
Troglodytes edon, var. aztecus, Baird, Rev. Am. B. i. p. 189°. 
Troylodytes aztecus, Sumichrast, Mem. Bost. Soc. N. H. i. p. 545". 
Supra murino-brunneus, uropygio paulo rufescentiore ; dorso, alis et cauda nigro transversim fasciatis ; subtus 
griseo-albidus fusco vix irroratus, hypochondriis et crisso leviter fusco transfasciatis, rostri maxilla 
