NATURAL SCIENCES OF PHILADELPHIA. 497 



Sp. Char. Wing, 7.10-7.75 ; tail, 0.30-7.00 ; culmen, .GO ; tarsus, 

 2.25-2.45; middle toe, 1.00-1.08. Adult: Above uniform plum- 

 beous; tail, blackish-dusky, narrowly tipped with white, and 

 crossed 3-4 narrow bars, or lines, of the same. Beneath white, 

 the throat sometimes faintly tinged with ashy, the breast and sides 

 with narrow transverse bars of dusky, anal region, crissum, and 

 lining of the wing, always immaculate. 



Remarks This very distinct species may be immediately dis- 

 tinguished by the peculiar proportions of the lateral toes, and by 

 having the tail shorter than the wing ; while in its adult dress it 

 is unique in the white thoat and unbarred crissum and anal region, 

 as well as by the yellowish instead of dusky color of the bill, 

 though we are not sure of the constancy of the latter feature. 



The shade of plumbeous of the upper parts generally inclines 

 to brownish posteriorly, and becomes more bluish toward the 

 head, especially on the neck ; the feathers of the lower half of the 

 rump are white, tipped with plumbeous. 



A specimen from Cayenne, in Mr. Salvin's collection, has not 

 only the parts described, but also the abdomen, flanks, and tibiae, 

 unbarred ; the crown is decidedly darker than the back, and the 

 neck has a very perceptible bluish cast. Other peculiar features 

 mark this as a young bird in transition plumage. 



The proper name for this species is involved in considerable 

 uncertainty from the difficulty of ascertaining just what bird two 

 of the older authors Vieillot and Lesson had in view when they 

 described their Sparoius gilvicollis and Nisus concentricus. Herr 

 von Pelzeln (Orn. Nov. p. 10) identifies in the former the bird 

 which we describe as the plumbeous phase of M. ruficollis, while 

 the latter he considers to be the bird now under consideration. 

 Messrs. Sclater and Salvin, however, differ from Herr Pelzeln 

 (Proc. Zool. Soc, 1859, p. 368), and regard these two names as 

 synonymous, basing their opinion on the fact that M. Puclieran 

 had compared the types of each, then in the Paris Museum, and 

 had pronounced them indentical; and gilvicollis being the older of 

 the two names, Messrs. Sclater and Salvin accordingly adopted that 

 for the present bird. We are not so ready, however, to accept M. 

 Pucheran's conclusions as a final settlement of the point, for the 

 bird which Vieillot describes as Sparvius gilvicollis is certainly 

 not this bird, and the error of this indentification becomes at once 

 apparent upon reading Vieillot's description, which is as follows, 



