694 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



family Sylviinse is entirely Palsearctic, and includes such well-known 

 European birds as the Blackcap {Sylvia atricapilla), Whitethroat 

 {Sylvia cinerea)^ Sedge Warbler {Acroceplmlus phragmitris). Reed 

 Warbler {A. arundwiadeus). Grasshopper Warbler {Locustella nmvia), 

 etc. The so-called Regulinse (which I am unable to separate from the 

 Phylloscopinse) are circumpolar and much more limited in its mem- 

 bers, which are less than a dozen in number of species, belonging to 

 a single genus, and about equally divided between the Nearotic and 

 Palsearctic regions. The Potioptilinse are almost equally circum- 

 scribed, but of much more limited range, being peculiar to the warmer 

 parts of America. 



KEY TO THE AMERICAN SUBFAMILIES OF SYLVIIDjE. 



o. Acrotarsium booted (in American species) ; tail much shorter than wing, even or 

 emarginate, the rectrices subacuminate at tip; color of upper parts more or 



less olive or olive-green; tail without black PhylloscopinaB. 



aa. Acrotarsium scutellate; tail about as long as wing, much rounded, the rectrices 

 broadly rounded at tip; color of upper parts bluish gray or grayish blue 

 (rarely brownish in young), sometimes with pileum black; tail mostly black. 



Folioptilinse. 



As stated above, I am unable to sepai'ate the genus Eegulus from the 

 Phylloscopinse, at least by external structural characters, which are 

 very closely identical with those of Eeguloides, the latter being in fact 

 intermediate between Regulus and Acanthopneuste. It is true that Reg- 

 nlus cristatus and other species of the genus have a very peculiar mod- 

 ification in the character of the antrorse latero-frontal plumules, one of 

 which is much larger than the rest and projects over the nostril; but 

 R. calendula does not possess this peculiar feather, the latero-frontal 

 plumules differing from those of Reguloides and Acanthopneuste in no 

 essential respect, so far as I am able to discover. 



Genus ACANTHOPNEUSTE Blasius. 



Acanthopneuste Blasius, Naumannia, 1858, 313. (Type, Phyllopneuste borealu 

 Blasius. ) 



Small, plainly colored Sylviidse with booted acrotarsium and exposed 

 nostrils, and with exposed culmen equal to or longer than middle toe 

 without claw. 



Bill more than half as long as head (exposed culmen equal to or 

 longer than middle toe without claw), broader than deep at base; 

 culmen straight to near tip where decidedly decurved, the tip of the 

 maxilla minutely uncinate; gonys faintly convex or nearly straight, 

 about as long as distance from nostril to tip of maxilla. Nostril 

 exposed, longitudinal, narrow, distinctly operculate. Rictal bristles 

 long, very distinct; latero-frontal feathers erect or semiantrorse, with 

 distinct bristly tip. Wing rather long and pointed; eighth, or eighth 



