184 NUMBER OF PEIMAEIES IN OSCINE BIRDS 



birds, the additional primary, makiDg 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 

 Osoines, 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 oases lengthening by imper- 

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

 nature of tlie 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 ? 



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

 posUion 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. lu 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 both are rudi- 

 mentary remiges. To offset this, co?or usually points the other way, as in 

 the original case of Vireo flavlfroiis, 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 t;hat the tes- 

 timony from coloration is sometimes the other way. In Silta caroJinoisis, 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 

 determinatioDS, 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 couclusive 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 teetrix are ascertained. Should it be determined that an 

 Oscine may show traces of two su])pressed primaries, instead of only the 

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

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

 taxonomio factor. It is generally admitted, and it seems to he unciuestlona- 

 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 



