NATURAL SCIENCES OP PHILADELPHIA. 
41 
figures and diagnoses of the various authors who have treated of this 
bird has shown that there are assigned to AEgiothus Holbblli , as dis- 
tinctive characters, exactly those differences from the linarius which exist in 
the specimens under consideration, — viz. : larger size, larger, more elongated 
and bright yellow bill, and larger gular spot. I think there can he no reason- 
able doubt that these specimens represent in North America the form long 
recognized in Europe under the name of AEgiothus Holbolli. 
If this be the case, next comes the question, what rank are we to accord to 
this form. Is it to be looked upon as an accidental variation from the type, — 
as a well marked variety, — or as a distinct species ? Brehm was the first to 
proclaim it as distinct, and give it a name. Temminck, Schlegel, Bonaparte, 
and other authors, — who are rather more orthodox in their ideas of a species 
than is Brehm, — have always inclined, more or less decidedly, to the opinion 
that it is rather a race or subspecies of A. linarius . The fact of there being a 
complete gradation towards the linarius , has not escaped attention, and has 
been a powerful argument against according to it full specific rank. For my 
own part, though unable to demonstrate the point incontrovertibly, I am in- 
clined to reiterate still more strongly the doubts expressed in my Monograph, 
as to the propriety of separating it from the linarius. 
Pursuing this question of the variations which A. linarius presents, we find 
another species, — A. rufescens , — which has never been able to fully vindicate its 
claims to specific distinction. First introduced by Vieillot, its existence was 
strenuously denied by Temminck, doubtfully regarded by Bonaparte and 
Schlegel, and admitted by Cabani^ and others. I have always entertained 
strong doubts as to its validity. The characters assigned are slight enough ; 
and that they exhibit a gradation towards A. linarius , is admitted even by 
those who contend for its separation from that species. In examining two 
hundred or more specimens, I find many individuals, fully as small, in fact, 
and with as much of a reddish tinge, as specimens from Europe labelled “ ru- 
fescens ” by good authority. 
The existence, then, in North America of these two races, or species, which 
ever they may be, the one larger and the other smaller than the typical lina- 
rius , may be considered as exceedingly probable, if the fact be not actually, 
demonstrable. As a sort of negative argument,' I may remark, that one 
might naturally look for their occurrence in this country as the typical lina- 
rius from Europe is absolutely identical with our own. 
AEgiothus rufescens and A. Holbolli , compared with A. exilipes, afford a good 
illustration of the limits between which a species may vary from its normal 
type ; while another species, looking at first glance more like this type than 
do either of its extremes, is permanently distinct. 
I have no reason to change any of the views expressed with regard to three 
new species I have introduced. Additional specimens confirm the position as- 
sumed, especially regarding A. exilipes. I may here, however, correct a 
typographical error, which gives the date of the first introduction of A. fuscss- 
cens as “ Aug., 1860,” instead of “ Aug., 1861.” 
