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 sEgiothus Holbolli, 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 be no reason- 

 able doubt that these specimens represent in North America the form long 

 recognized in Europe under the name of JEgiothus 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, Sthlegel, 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 li 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, m ay 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 tbe typical lina- 

 rius from Europe is absolutely identical with our own. 



JEgiothus 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. fusees- 

 census "Aug., 1860," instead of "Aug., IStil." 



March 3d. 



Mr. Jos. Jeanes in the Chair. 



Twenty members present. 



Tbe following paper was presented for publication : 

 Enumeration of the plants collected by Dr. Parry, and Messrs. Hall 

 and Harbour, in Colorado Territory. By Asa Gray. 



1863.] 4 



