OCR Text |
Show 1878.] MR. J. H. GURNEY ON A SPECIMEN OF POLYBORUS. 231 On the 27th of May, 1877, one of these birds unfortunately died ; and on examining the skin of this specimen, which proved on dissection to be a male, I have noticed the following points. The wing measures 15*6 inches; but the ends of the primaries are worn considerably, and except for this the measurement would, I think, have exceeded 16 inches ; the length of the tarsus is 3*7, and that of the middle toe s. u. 2*3 inches. I have had the opportuuity of comparing these measurements with those of four specimens of Polyborus tharus which have been kindly lent to m e by Messrs. Salvin & Godman, and with those of two specimens in the Norwich Museum ; also with the measurements given by M r . Sharpe, at p. 32 of the first volume of his Catalogue, of two others in the British Museum. Unfortunately in none of these eight examples is the sex recorded ; but the result appears to prove that Polyborus tharus is subject to considerable variation of size, which further investigation may show to be incident, in part, to the different localities from which the specimens have been obtained. The following are the measurements alluded to :- In the collection of Messrs. Salvin & Godman. Bahia 9) Supposed to be from Bolivia In the Norwich Museum. Locality unknown 5> In the British Museum, as given by Mr. Sharpe. Locality not quoted Wing. 14*8 15*1 15*6 16*0 17*2 17*4 15*5 Tarsus. 3*0 3*5 3*5 3*5 3*7 3-9 3*8 Middle toe s. u. 1*9 2*2 2*1 2*2 2*3 21 17*9 3*8 It will be seen from the above measurements that there is nothing in the dimensions of the specimen which died at the Gardens to show that it is not an abnormal example of P. tharus ; and although the extraordinary paleness of the ground-colour of its plumage presents a curious difference from the coloration of the same portions of the plumage in P. tharus, the form and disposition of the markings in great measure agree with those of that species in its immature stage. The following notes refer to the details in which the pale specimen agrees with the ordinary P. tharus in its immature stage :-The upper part of the head, including the occipital crest, is decidedly darker than the adjacent plumage ; the ear-coverts are whole-coloured and of a castaneous tint; the feathers of the throat and upper breast have strongly marked longitudinal shaft-marks ; and similar shaft-marks, but narrower and fainter, are perceptible on the lower breast |