150 Proceedings of the Biological Society of Washington. 



forms) ; nasal operculum largely covered by feathers (sordida, etc.) 

 or much more exposed (erythrops, subcristata, etc.). 



Cranioleuca Reichenbach.* 

 (Type Snyallaxis albiceps d'Orbigny and Lafresnaye.) 



c. Tail long, strongly and evenly graduated! and from 1 J^ times length 



of wing to nearly twice length of wing; tail feathers slightly narrowed 

 terminally, the ends blunt not sharply pointed; wing about 3 times 

 length of tarsus; frontal feathers stiffened and sharply pointed; 

 hallux (without claw) shorter than outer toe (without claw). 



Pseudosiptornis, gen. nov. 

 (Type Siptornis ottonis Berlepsch.) 



d. Tail long, unevenly graduated; tail feathers blunt, the three middle 



pairs gently graduated, the fourth pair (from outside) at least % as 

 long as middle pair, and first, second and third pair abruptly and 

 strongly graduated; wing about 3J4 times length of tarsus; tail 

 about \}/2 times length of wing; hallux (without claw) shorter than 

 outer toe (without claw) Siptornopsis, gen. nov. 



(Type Siptornis hypochondriacus Salvin.) 

 B. Tail feathers decidedly attenuated terminally and most of the feathers 

 sharply pointed; tarsus 1-3 or more length of wing; plumage on upper 

 parts or under parts or both conspicuously streaked 



Siptornoides, gen. nov. 

 (Type Siptornis flammulata Jardine.) 



a. Plumage streaked above and below, general plumage dark streaked 



with white or whitish. Siptornoides (typica). 



b. Upper plumage tawny or buffy streaked with black; under parts 



largely or entirely without streaks Eusiptornoides, subgen. nov. 



(Type Synallaxis anthoides King.) 



The measurements of wing, tail and tarsus of the species and subspecies 

 belonging to the above genera and subgenera are as follows. J An asterisk 

 before a name indicates I have not seen specimens and that it is not repre- 

 sented in the British Museum. 



* I am unable to find any constant characters to distinguish the Genera Asthenes Reich- 

 enbach and Acrorchilus Ridgway from Cranioleuca. In the large number of specimens 

 examined I find considerable variation in the shape of the culmen and also in the extent of 

 the feathering which in some species nearly covers the nasal operculum and in others leaves 

 it mucn more exposed, but several species appear to be intermediate so far as this character 

 is concerned. The same conditions may be said to obtain regarding the relative length of 

 wing and tarsus, and that of the hallux and outer toe, which vary in combination in different 

 species to such an extent that their diagnostic value as distinguishing generic characters 

 are practically lost. The advisability of recognizing several subgenera in this group based 

 on color characters in connection with one or more of the above mentioned structural char- 

 acters remains to be determined, but to my mind little advantage would be gained. 



t Tail measurements of Pseudosiptornis ottonis (Berlepsch), cotype from Anta, Cuzco, 

 Peru (No. 99163, American Museum of Natural History, New York) — outer pair rectrices 

 40 mm.; 2d pair 55; 3d pair 70; 4th pair 85; 5th pair 100; middle pair 115 mm. 



1 1 am greatly indebted to my friend Mr. Charles Chubb for measurements of a number 

 of type specimens, and others in the British Museum. 



