NATURAL 8CIENCE3 OF PHILADELPHIA. 127 



nella magna and S. neglecia — Ci/anura stelleri and C. macrolopha — Cyanocitta 

 californica and C. ivoodhousii — Anser gambelii and Bernicla huichinsii, and many 

 others which, I need not here mention — all, I may again say, from the regions 

 ■where the habitats of the two representative species overlap. 



Premising these general considerations I proceed to discuss in detail some 

 closely allied species to which my attention has been specially called in the 

 course of the investigations referred to. 



1. The North American Wood Thrushes. 

 Genus HYLOCICHLA, Baird. 



Some authors seem inclined to doubt the validity of several species of this 

 group, as characterized by Professor Baird. These are the H. aliciie, Baird, IT. 

 ustulaius, Nutt., H. nanus, Audubon, and H. audtibonii, Baird, these being refer- 

 red to sivainsonii, Ceibn.n\s, fuscescens, Stephens, and pallasi, Cabanis. A careful 

 examination of the very extensive series of these birds in the Smithsonian 

 collection has, however, convinced me that they are all (with perhaps the ex- 

 ception of audubonii) justly to be regarded as distinct species. 



I do not propose to speak here at any length in regard to the characters of 

 these species, as they have been well presented by Professor Baird, in his 

 work on the "Birds of North America," and in his later "Review of Ameri- 

 can Birds," but intend merely to give a few additional features which the 

 species constantly present in distinction from one another. The more im- 

 portant synonyms only are given. 



The species I arrange according to the following synopsis : 



A. Upper surface much brightest anteriorly, the rufous of the crown being 

 decidedly more intense than the olive of the posterior portions; white be- 

 neath continuous ; spots large, sharply defined, pure black, and extending 

 far back. 



This style is represented by a single species, the well known T. musleiinus, 

 Gm., which needs no comparison with any other. 



B. Olive of back uniform from head to tail, but varying in shade. 



T. fuscescens, T. iisliilatus, T. sivainsoni and T. alicise are of this pattern. 



C. Olive of the back passing very sensibly, or even abruptly, into reddish on 

 upper tail coverts and tail. 



The species representing this style are the T. pallasi, T. audubonii and T. 

 nanus. 



TuROnS FUSCESCENS. 



Turdus fuscescens, Stephens, Shaw's Gen. Zool. Birds, X, i, 1817, 182 — Baird, 

 Birds N. Am. 1858, 214. — Turdus i^Hylocichla) fuscescens, Baird, Rev. Am. Birds, 

 I, 1864, 17. 



Sp. ch. Above tawny rufescent olive, uniform on all parts, but occasion- 

 ally with a tendency to a greater intensity on dorsal region. Pectoral aspect 

 peculiar; throat with a series of faint brown dashes on each side, these 

 continuing down sides of neck and extending very sparsely across the breast, 

 where they become more sharply defined ; the region of these markings with 

 a fine cream colored tinge, quite different from the buff of ustulaius and 

 mvainsonii. Like the T. aliciss, this species lacks entirely the yellowish or 

 lighter orbital ring. 



Turdus ustulatus. 



Turdus ustulaius, Nuttall, Man. I, 1840, 400— Baird, Birds N. Am. 1858, 275, 

 pi. Ixxvi, fig. 1. — Turdus {Hylocichla) ustulaius, Baird, Rev. Am. Birds, I, 1864, 

 18. 



Sp. ch. General appearance of fuscescens, but with pattern of swainsonii, the 

 buff orbital ring as conspicuous as in latter. The olive above is more brotvn 

 than in this, and less yellowish than in fuscescens, becoming decidedly more 



1869.] 



