380 
PROCEEDINGS OP THE ACADEMY OP 
great, the species is so marked, and so distinct from any other that there would 
be no difficulty in recognizing it. The difference in the length of wing of the largest 
male and smallest female before me is barely three-eighths of an inch. The 
bill constantly preserves its peculiar size and shape, and in very young birds, 
still in the downy state, is quite different from that of any other species. The 
color of the upper parts hardly varies appreciably. The edgings of the wings 
differ somewhat in breadth, but are never so broad as those of Unarms. The 
claws vary considerably in acuteness and amount of curvature ; the difference, 
however, being caused apparently by a greater or less amount of wearing away 
of the sharp tips. 
Comparison with allied species . — The present species, possessing such marked 
characters, hardly requires comparison with any other except fuscescens. As 
already stated, it is much larger than that species, the difference in the length 
of the wings being nearly half an inch. The next greatest difference is seen 
in the bills. That of A. fuscescens is larger and every way stouter than that of 
Imarius , but the differences between fuscescens and rostratus in this respect are 
even greater. As regards color, the two are almost identical, except that in 
rostratus the dusky streaks of the sides usually extend quite across the lower 
part of the breast. 
From A. linarius and still more from A. rufescens , the differences are suffi- 
ciently obvious. It differs in color exactly as does fuscescens , and, in addi- 
tion, in the greatly superior size, and the enormously large bill. A. Holbfilli 
has a long and robust bill ; but it is bright yellow, not dusky horn color ; and 
the general colors of the bird are those of linarius. 
In size this species about equals A. canescens ; but here the resemblance 
ends. The general very dark, instead of very light colors ; the heavily streaked, 
instead of immaculate sides ; the very large and arched, instead of small and 
conic bill ; and the very different proportions of tarsus, toes and claws, with 
other characters, at once separate the two. 
It is unnecessary to institute a comparison with A. exilipes , the characters in 
almost every particular being exactly opposite. 
Remarks . — It seemed to us hardly possible that so very distinct a species as 
the present could, at this late day, have remained undescribed. We accord- 
ingly searched with care all the authorities on the subject, which the libraries 
of the Smithsonian and the Academy contain, but could find no notice of it. 
Holboll, Temminck and other authors, who admit the A. canescens , have gone 
considerably into detail with regard to its variations and changes of plumage, 
which, as well as those of A. linarius , are now well known, and a pretty defi- 
nite “ theory of variation ” of the genus established. But seasonal or sexual 
changes of plumage, even the most abnormal, could never produce the marked 
difference in the size and shape of the bill, and the proportions of the feet and 
toes. Having therefore been unable to find any description which ap- 
plies even approximately, Ave have ventured to impose a name, feeling quite 
assured, that if we are in error in so doing, some one will before long correct 
the mistake. 
The specimens upon which the species is founded were, with one exception, 
received from the Copenhagen Museum, to which we are indebted for a fine 
series of several species, kindly transmitted for examination. They are label- 
led as having been obtained in Greenland. 
yEGioTHUs fuscescens Coues. 
Aegiothus fuscescens Coues, Notes Ornitli. Labrador, in Proc. Acad. Nat. Sci. 
Phil., Aug. 18Q$ p. 222. 
Diag. A. JEgiotho linario paululum minor, rostro fusco magno robusto, 
plumulis brevibus sparsisque, superioribus partibus fuscis vix luteo striatis, 
alis caudaque vix albido marginatis, lateribus distinct^ nec confluente fusco- 
striatis. 
