240 Mr. P. Ij. Sclater on two 



P.S. — MoTAciLLA FLAVA. "And are therefore of var. tai- 

 vanus" (Seebohm in Ibis, 1884, p. 39). Budijtes taivanus, 

 Swinboe, is the most perfectly distinct of all Wagtails. It 

 differs even structurally, having a longer and stronger bill, also 

 longer and stronger legs and feet. The coloration is unique. 

 If it be not a thoroughly good species, then there is not 

 such a thing as a good species. 



XXVII. — Remarks on two rare American Oscines. 

 By P. L. Sclater, M.A., Ph.D., F.R.S. 



(Plate VII.) 



As mentioned in my last article on the Icteridse (Ibis, 1884, 

 p. 167), the anthoritifes of the U.S. National Museum have 

 kindly sent to me for inspection the type of Jdiopsar bra- 

 chyurus of Cassin. From the same obliging correspondents 

 Mr. Salvin has obtained the loan of the only two known 

 sjDccimens of Acanthidops bairdi of Ridgway. I venture to 

 offer a few remarks upon these two rare and little-known 

 species. 



Idiopsar brackyurus (Cassin, Pr. Ac. Nat. Sc. Phil. 1866, 

 p. 414) is one of the most singular South- American types I 

 have seen for a long while. Although the wings of the 

 unique specimen are in process of moult, their structure and 

 that of the feet show that it is a nine-primaried Oscine. 

 But I have much doubt whether it is best referred to the 

 Icteridae, as Cassin has proposed. The square tail and cast 

 of plumage remind one more of some of the Fringillidse of 

 the genus Phrygilus, especially Phrygilus unicolor, which in 

 style of plumage it closely resembles. The bill is certainly 

 very abnormal for a Fringilline bird, but hardly more divergent 

 from tbe ordinary Fringilline structure than that organ is in 

 the case of such types as Catamblyrhynchus, Piezorhina, and 

 Xenospingus. On the other band I can find no bill among the 

 Icterines nearly similar to tbat of Idiopsar, and in plumage 



