184 NUMBER OF PRIMARIES IN OSCINE BIRDS 



birds, the additional primary, making ten in all, is usually, if not always, 

 found in the second of these little quills which overlie the first fully devel- 

 oped primary ; and that it is this same little quill which, in 10-primaried 

 Oscines, in Clamatores, and probably in other birds, comes to the front and 

 constitutes the first regular primary sometimes remaining very short, when 

 it is the so-called "spurious" quill, in other cases lengthening by imper- 

 ceptible degrees, until it may become the longest one of all. The true 

 nature of the other one of these two little feathers becomes an interesting 

 question : Is it also an abortive primary, as the outer certainly is, or is it one 

 of a series of coverts f 



After close examination, I fail to detect any material difference in the 

 position of the two ; one overlies the other, indeed, as a covert should a pri- 

 mary, but then the two are inserted side by side, both upon the upper side 

 of the sheath of the first fully developed quill. In size and shape, the two 

 are substantially the same; both being rigid and acuminate, more like re- 

 miges than like coverts, and both being abruptly shorter than the true primary 

 coverts. So far, all the evidence favors an hypothesis that botlr are rudi- 

 mentary reniiges. To offset this, color usually points the other way, as in 

 the original case of Vireo flavifrovs, in which Professor Baird determined 

 the underlying one of the two feathers to be a supposed wanting primary 

 mainly because it was colored like the other primaries, while the overlying 

 one agreed with the coverts in this respect. But it will be obvious that 

 when, as is ofteuest the case, the primaries and their coverts are colored 

 alike, the evidence from this source fails altogether; and I find that the tes- 

 timony from coloration is sometimes the other way. In Sitta caroUnensia, for 

 example, a 10-primaried bird with spurious first primary, the single remain- 

 ing little feather is white at base across both webs, like the primaries, the 

 true primary coverts being white only on the inner web. It is true that the 

 overlying one of these little feathers sometimes exactly resembles a true cov- 

 ert ; but so, also, does the other one in some cases. In morphological 

 determinations, position and relation of parts are all-important, while mere 

 size, shape, and especially function, go for very little. One of the two little 

 feathers of 9-primaried birds, as we have seen, certainly corresponds to the 

 spurious or fully developed first primary of 10-primaried; why may not the 

 other be also a primary? It is not conclusive argument to the contrary that 

 the feather in question is never fully developed; nor is it an insuperable 

 objection that the function of the feather is certainly that of a covert. The 

 strongest argument against the view here very guardedly discussed is, that 

 if the feather be not a covert, then the first fully developed primary has 

 none, while the rest have one apiece. While I am far from committing my- 

 self to the implied proposition that an oscine bird possesses eleven primaries, 

 I think it proper to bring the case forward as one which will bear looking 

 into, and which will probably remain open until the exact relations between 

 a remex and a tectrix are ascertained. Should it be determined that an 

 Oscine may show traces of two suppressed primaries, instead of only the 

 single one which certainly persists in 10-primaried birds, the fact would 

 tend to increase the value already justly set upon number of reniiges as a 

 taxonomic factor. It is generally admitted, and it seems to be unquestiona- 

 ble, that here, as in numberless other cases, reduction in number and special- 

 ization in function of parts indicates a higher grade of organization ; for 



