128 REVIEW OF AMERICAN BIRDS. [PART I. 
or membrane of Thryothorus and Pheugopedius, leaving the nasal 
aperture to occupy the anterior extremity of the nasal groove, with 
the internal lateral septum exposed, but vertical, and extending for- 
ward to the anterior extremity of the nostril, not ending abruptly 
behind. This is a peculiarity very easily appreciated in most cases. 
The generic name of Thryothorus belongs to T. ludovicianus as 
type. Prince Maximilian has used Hylemathrous for a South Ame- 
rican Wren (his platensis); which, however, Cabanis assures us is 
strictly congeneric with Troglodytes xdon (Journal fir Orn. 1860). 
Finding, therefore, no name ready at hand for this group, I am com- 
pelled to make a new one. 
The genus differs from Campylorhynchus in having a notched bill, 
and a more open nostril, lacking the supra-nasal ridge or sometimes 
scale seen in nearly all excepting C. capistratus, and its allies ; and 
from this it differs in having the lateral septum exposed, not con- 
cealed by the nasal membrane behind; the legs also are much more 
feeble. Heleodytes has much stouter legs, an unnotched bill, the 
tarsus not longer than the middle toe and claw. 
A synopsis of the principal species will be found under Thryothorus. 
Thryophilus rufalbus, var. rufalbus. 
Thryothorus rufalbus, LAFRESNAYE, R. Zool. 1845, 337, Mexico? (more 
probably 8. America).—LAawrence, Ann. N. Y. Lyc. 1863 (Pana- 
ma).—CaBAnis, Jour. Orn. 1860, 408 (Costa Rica).—Sciater, P. Z. 
8. 1856, 140 (David, Chiriqui). 
? Troglodytes cumanensis, Licut. Cab. Jour. 1860, 408 (Carthagena). 
Hab. Isthmus Panama; New Grenada; Costa Rica? 
Thryophilus rufalbus, var. poliopleura. 
Thryophilus poliopleura, Barrp. 
Thryothorus rufalbus, Schater & Sanviy, Ibis, 1859, 8 (Guatemala) ; not 
of LAFRESNAYE. 
Hab. Guatemala. 
I find, on comparison of a series of Wrens labelled 7. rufalbus 
from different localities, some important differences which .appear, 
taken in connection with the geographical distribution, to be almost 
of specific value. Cabanis has already suggested a difference of 
species, although not exactly on the same grounds that present them- 
selves in the specimens before me. 
As Cabanis remarks, the typical species of Lafresnaye is probably 
to be found from northern New Grenada—the locality given of 
“Mexico” being most likely erroneous. The Bogotan specimens 
differ in smaller size, less extent of white beneath, and greater 
