DUSKY THRUSH. 43 



to the former group. The three birds with rusty red colouring are 

 interesting to us, for they represent, more or less, T. Naumanni in 

 advanced age." 



Dr. Radde here describes a bird which has the striking charac- 

 teristics of both T. fuscatus and T. ruficollis, and he calls it the 

 result of a cross between the two. The reviewer of Radde's work, 

 however, in the "Natural History Review," 1865, remarks: — "And 

 here we may remark that Herr Radde has, we believe, committed a 

 serious error in identifying T. Naumanni, Temminck, so well dis- 

 tinguished and illustrated in the last supplementary volume of 

 Naumann's 'Vogel Deutschlands,' with T. rujicollis, of Pallas; the 

 latter being a very distinct species more nearly allied to T. atrigularis. 

 Nor can we believe that the bird figured on pi. 8 of his work is 

 really a hybrid between T. fuscatus and T. ruficollis. It appears to 

 us to be nothing more than a young T. Naumanni. Although the 

 young birds of the latter species are somewhat difficult to distinguish 

 from those of T. fuscatus, yet a large suite of specimens renders 

 this task comparatively easy, as we have occasion to know from our 

 examination of the very extensive series of them procured by Mr. 

 Swinhoe in various parts of China." 



Dr. Radde, carrying on the idea of hybridism, says that the other 

 two skins in the second moult agree with T. Naumanni in the 

 transition plumage perfectly, and these birds are represented in 

 Naumann by fig. 2, pi. 358, where it is designated a two year old 

 bird. After describing these specimens Dr. Radde continues: — 



"It is strange to me that after the apparent agreement of the 

 Siberian^ collected materials, these typical stages of plumage in T. 

 fuscatus are those found in greater accordance where T. ruficollis is 

 rare, as, for example, in the countries bordering on the mouths of 

 the Amoor; while, on the other hand, in the lands about the source 

 of the river, where that form known as T. Naumanni and T. ruficollis 

 live together, the typical form of T. fuscutus is much more rare. 



"It is remarkable that I did not meet with either T. fuscatus or 

 T. ruficollis in the wide conifer plantations on Lake Baikal, In 

 the east of Sajan, however, T. fuscatus breeds in the countries near 

 the sources of the Irkut, in the outermost limits of the woods, 

 especially at the boundary posts of Turansk and Chungnisk. On the 

 2nd. of July, 1859, the young were already fledged. The principal 

 flocks appear on the Tarei-Nor from the 2nd. to the 5th. of May, 

 their forerunners as early as April 5th. They begin to call about 

 March 25th., and to sing loudly on April 17th. I never saw this 

 bird in the south of Siberia in winter." 



