15 



D 



markings of black and fulvous white in alternate transverse lines on each of the feathers, and on several 

 of them is seen a very distinct appearance of blue. This we are unable to account for, as on none of 

 these specimens is an exact indication of the time when they were obtained. They bear a label of Mr. 

 Swinhoe's, "S.-W. Formosa, 1861." If we may judge from a paper on Formosan Ornithology by Mr. 

 Swinhoe in ' The Ibis ' for 1863 (p. 27-1), he appears to have been in the south-western part of the island 

 in the autumn of 1861. In this paper he says : — " The female retains the mottled plumage through life ; 

 but the young male in the first autumnal moult shows a good deal of blue on the back and throat, and 

 red on the lower parts : the plumage becomes more defined in the following spring ; but the mottles 

 do not entirely disappear till the close of the second year, and often not then." The absence of a date 

 ou the labels of these peculiarly marked individuals prevents us from hazarding any opinion as to their 

 probable age ; but we do not believe that they are birds of the year. Another male specimen, procured 

 at Takow, in Formosa, in October 1865, is in the plumage that we should expect to find in the bird of 

 the second year. It is in ordinary blue-and-red dress, with remains of escalloped markings on the 

 breast and of the usual bars on the rest of the body. Whether these marks are the remains of young 

 plumage, or are the commencement of a second winter dress, we must leave to the observations of Mr. 

 Swinhoe on the birds in a wild state to discover. We give further remarks on some of the Formosan 

 specimens in our analysis of the material examined further ou. It is sufficient for our present purpose 

 to trace the bird through its several stages, from the spotted dress to the blue-and-red ; and we have 

 now seen that a blue shade is beginning to overspread the abdomen. The next specimen we describe 

 is one in Mr. Swinhoe's collection, from Amoy, unfortunately without any exact date attached. 



Adult Male assuming the entire blue plumage. Entire upper surface of the body cobalt-blue, more brilliant 

 on the head and rump ; throat and upper part of the breast also blue, more dingy on the latter, but 

 brighter on the throat itself; the wing externally washed with dull blue, with a very narrow white 

 edging to the greater as well as the primary coverts and inner secondaries ; rest of the under surface 

 of the body pale chestnut, almost fading into orange ; most of the feathers on the flanks and some in 

 the centre of the belly blue, with slight remains of a whitish cross bar ; under tail-coverts entirely 

 chestnut, with a blackish tip to two of the outer feathers ; under wing-coverts pale chestnut, shading 

 into blue, most of them having already assumed the latter colour. 



By this time our conclusion will be apparent to our ornithological readers, viz. that the Eastern Blue Rock- 

 Thrush does not stop at the blue-and-red plumage, which is usually considered to be the fully adult 

 dress, but continues to change, the belly becoming gradually blue, till at last it reaches a blue dress 

 undistinguishable from that of its European ally. Besides specimens in the plumage just described, we 

 have others with the whole of the under surface blue, excepting the under tail-coverts, and others 

 entirely blue, with only a single feather tinged with chestnut, the last remains of the red belly. Many 

 writers have commented upon the admixture of red and blue which they found in some of their 

 specimens ; and we hope that the change is now satisfactorily accounted for. 



We next proceed to give a description of the specimens examined by us for the benefit of such students as 

 shall take up the study of this species, and we hope that some competent field-naturalist, like Mr. 

 Swinhoe or Mr. Hume, will be able to explain the exact mode in which the various changes are 

 effected in succession, an almost impossible thing for the closet-naturalist to do, working at home 

 and beset, in the present case, with the difficulties occasioned by the absence of dates to many of the 

 most important specimens. Never, perhaps, was there a better illustration than the present of the 

 good that can be effected by the united labours of field- and closet-naturalists. Working in England, 

 we have been able to examine an immense series of specimens in our own cabinets and those 

 of our friends; and this study has resulted in what we believe all ornithologists will agree to be an 

 important discovery. Whether our detailed account of the progress to maturity is absolutely correct, 



