740 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



structure the group could easily be subdivided into several genera; 

 but the existence of these intermediate forms seems to forbid such 

 subdivision. 



B. Gulicivorus is the only species in which the eighth primary is 

 equal, or nearly equal, to the longest, and (except B. leucoUepfiarm) 

 the only one in which the ninth primary is equal to or longer than the 

 third; yet this form is obviously very closely related to B. OMWcapillm 

 (the type of the genus). B. rufifrons is the only species which has 

 the tail longer than the wing, yet there can be no question of the close 

 relationship between B. nofifronn and B. hell% the latter having the 

 tail shorter than the wing. B. iiielanogenys has the bill relatively 

 much smaller and narrower than other species, being quite similar, in 

 that respect, to Ergaticits; but in other characters, including colora- 

 tion, it is a typical BasUentenis. The opposite development of the 

 bill is seen in B. semicervinus and related (probably conspecific) forms, 

 B. %i,ropygi.alis, B. veraguensis, and B. leucopygius; in these the bill is 

 shaped very much as in the genus Myiohorus, being almost equally 

 broad at the base, but is less depressed and relatively much larger. 

 In this group, too, the coloration is peculiar, the pileum being uni- 

 colored and concolor with the back, while the lower rump, upper tail- 

 coverts and basal half of the tail are buffy or ochraceous in abrupt and 

 strong contrast with the general uniform dark olive or olive-brown of 

 the upper parts. B. stragtilatus, however (of which, unfortunately, 

 I have not been able to examine a perfect specimen), seems to agree 

 in large and broad bill and other structural characters with B. semi- 

 cervinus, while having the three-striped pileum and dark-colored rump, 

 etc. , of the typical Basileuteri. B. fraseri (which has the bill inter- 

 mediate between that of B. semicervimus and the typical species, but 

 most like the former), presents a close approach in some characters as 

 well as in general appearance to Euthlypis, but differs from the latter 

 (as do all other Basileuteri) in having the tarsus at least one-third as 

 long as the wing, in having the ninth primary shorter than the fourth, 

 and in lacking white spots at tips of the rectrices. 



There are several species of the group which I have not been able 

 to examine. Until these are carefully compared with the others the 

 exact limits of the group can not be defined with precision; therefore, 

 it is possible that, with all the species before him, some one else may 

 be successful in the attempt to subdivide the genus which, as currently 

 recognized, certainly is a very heterogeneous group.' 



I would exclude from Basileuterus several species allied to Tric/im 

 nigrocristatus Lafresnaye, closely resembling in coloration ^Vilsm^a 

 pusilla; the species named being the type of Myiothlypis Cabanis.* 



' The following BasUmten have not been seen by me: B. mophrys, B. cinerekoUis, 

 B. auricularis, B. gmeiceps, B. leucophrys, B. mesoleucus, and B. boUmanm. 



'' Myiothlypis Oabanis, Mus. Hein., i, 1850, 17. (Type, Tnchas nigromstatus Lafree- 

 naye.) ("Von /(Uia, Fliege, und SAuffz; nom. prop.") 



