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. ludocicianus as 

 type. Prince Maximilian has used Hylemathrous for a South Ame- 

 rican Wren (his 2^^o.i^€nsis) ; which, however, Cabanis assures us is 

 strictly congeneric with Troglodytes sedon (Journal fiir 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 Campylorh ynchus in having a notched bill, 

 and a more open nostril, lacking the supra-nasal ridge or sometimes 

 scale seen in nearly all excepting C. capistralus, 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 Tliryothorus. 



Thryopliiliis lufallms, var. riifalbus. 



Thr ijothor us ruf albas, Lafresnaye, R. Zool. 1845, 337, Mexico ? (more 

 probably S. America). — Lawrence, Ann. N. Y. Lye. 1863 (Pana- 

 ma). — Cabanis, Jour. Orn. 1800, 408 (Costa Rica). — Sclatek, P. Z. 

 S. 1856, 140 (David, Cliiriqui;. 

 ? Troglodytes crimanensis, Light. Cab. Jour. 1860, 408 (Carthagena). 

 Hab. Isthmus Panama ; New Grenada ; Costa Rica ? 



Tliryopliilus rufaltous, var. poliopleiira. 



Tlirijojihilus poliopleiira, Baird. 



Thryothorus rufalpus, Sclater & Salvin, Ibis, 1859, 8 (Guatemala) ; not 

 of Lafresnaye. 

 Hab, Guatemala. 



I find, on comparison of a series of Wrens labelled T. rufalhus 

 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 



