Systematic Position of the SJieuth-bills. J 33 



B. Chionis alba. Immature example, lialf-fledged ; from 

 Laurie Island, South Orkneys (Jan. lOO^). In the 

 collection of the National Scottish Museum, Edinburgh. 



This interesting specimen was very courteously sent to me 

 for examination by Mr. Wm. Eagle Clarke. It has already 

 been illustrated in ' The Ibis' for Jan. 1906, but the accom- 

 panying illustration (text-fignre 2) depicts it in gi-eater detail 

 and from a different aspect. Considered as an example of 

 a young Wader, it presents what one might almost describe 

 as a weird appearance. The following notes seem, in view 

 of the aberrant nature of the Sheath-bills, to be worth 

 recording : — 



Nestling, half -fledged ; no indication on label of its 

 probable age. The plnmage consists of neossoptiles and 

 teleoptiles, with no indication of raesoptiles. The neos- 

 soptilic feathers may be again subdivided into prepennse 

 and preplumulae. 



(a) Teleoptiles. — White definitive or contour-feathers, 

 apparently similar to fully adult contour-feathers, are to be 

 observed on the wings (primary and secondary remiges and 

 coverts); in the tail, where they are not so strongly deve- 

 loped as on the wingj over the scapular region (so-called 

 humeral tract); in the mid-scapular region (corresponding 

 to the forks of the anterior spinal tract and forming the 

 mantle); over the rump and uropygium (corresponding to 

 the posterior spinal tract); and in the region corresponding 

 to the femoral tract (not shown in the drawing). 



On the ventral surface, white contour-feathers may be 

 observed on the whole of the fore-neck and upper breast, 

 just forcing their way through a thick growth of bluish-grey 

 down (preplumulre), which latter is very conspicuous. On 

 the lower breast, flanks, and abdomen white contour- 

 feathers are more conspicuous still, and are tipped with 

 greyish-brown prepennae. 



(b) Preplumulde. — Conspicuous bands or tracts of these 

 feathers are seen along the preaxial borders of the wings, 

 and in tracts apparently corresponding to the Apteria 

 spinale, A, colli laterale, and A. trunci luterale. Towards 



