120 



REVIEW OF AMERICAN BIRDS. 



[part I. 



flanks, anal region, and crissum somewhat like the back, but paler ; 

 the sides of the breast tinged with plumbeous. Length, 3.50; 

 wing, 2.05; tail, 1.35. 



(22,386.) Type. 



THRTOTHORUS, Vieill. 



Thr'yolhorus, Vieillot, Analyse, 1816, 45. (Type Troglodytes arundi- 

 naceus, " Troglodyte des Roseaux," Vieill. Ois. Am. Sept. II, 1807, 

 55 = Sylvia ludoviciana, Lath.) 



Bill compressed, rather slender ; height ahout one-fourth the length ahove. 

 Cnlmen and commissure gently curved throughout ; gonys straight ; tip very 

 obsoletely notched. Nostrils in the lower edge of anterior extremity of the 

 nasal groove, narrowly elliptical, overhung by a stiff scale-like roof of the 

 thickened membrane of the upper part of the nasal groove, the cresoentic 

 edge rounded. The septum of nostrils imperforate ; the posterior part of the 

 nasal cavity with a short septum projecting into it parallel with the central, 

 not perpendicular as in Microcerculus. Wings and tail about equal, the latter 

 moderately rounded ; the first primary more than half the second, about half 

 the longest. Tarsi rather short, scarcely exceeding middle toe. Anterior 

 scutellse distinct, rest of each side of tarsi in a continuous plate. Lateral 

 toes equal. 



The type of the genus, as established by Vieillot, is his Troglo- 

 dytes arundinaceus, by G. R. Gray and others referred to the Gisto- 

 thorus palustris, but while the account of the nidification and general 

 habit applies best to the latter, the description and figure unquestion- 

 ably relate to T. ludovicianus. (See also Baird, Birds N. Am. 

 1858, 359.) 



As remarked elsewhere, the Wrens formerly included in the genus 

 Thryothorus are found to embrace several distinct groups character- 

 ized by the form of the nostrils, and to some extent by the shape of the 

 bill and the degree to which this is notched at the tip. As restricted, 

 the species of Thryothorus, characterized by the linear nostrils 

 moderately overhung by a thickened scale, all belong to North 

 America, and constitute two sections : one with T. ludovicianus as 

 type; the other (Thryomanes, Sclater) with slenderer, longer bill, 

 and the tail longer than the wings, its feathers broader, best repre- 

 sented by hewickii. The other divisions — Pheugopedius and Thryo- 

 philus — are peculiar to Middle and South Arieriea. 



