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. Taillong, strongly and evenly graduatedt and from 114 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 7% as 
long as middle pair, and first, second and third pair abruptly and 
strongly graduated; wing about 314 times length of tarsus; tail 
about 114 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.t An asterisk 
before a name indicates I have not seen specimens and that it is not repre- 
sented in the British Museum. 
*T 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 much 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 ch ters 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 reotrices 
40 mm.,; 2d pair 55; 3d pair 70; 4th pair 85; 5th pair 100; middle pair 115 mm. 
tI am greatly indebted to my friend Mr. Charles Chubb for measurements of a number 
of type specimens, and others in the British Museum. 
