'622 



PROF. J. COSSAR EWART ON THE 



and Emdeii geese the tail-quill pfotoptiles — though possessing a 

 long, sbrong calamus firmly connected with the rhachis of the tail- 

 quill, a well-developed shaft, and an aftershaft made up of twelve 

 T3arbs — are not pi'ovided with broad distal barbules armed with 

 hook-like cilia. In goslings, as in ducklings, the inner segment 

 of the calamus of the tail-quill protoptile is continvious with the 

 rhachis of a vestigial tail-quill aftershaft. 



Text-fio-ure 8. 



Two of the proximal bavbules of a tail-qail] protoptile; they are narrow 

 and armed with small cilia. X 64. 



Text-figure 9. - 



'Three of the hroad distal tail-quill barbules armed along one edge with tooth-like 

 cilia (Jiamuli) of true feathers. X 64. The difference between the simple 

 proximal and the specialized distal barbules is also indicated in text-fig. 6. 



{i) The Tail-Quill MesojJtiles. 



In sixteen of the tail-quill protoptiles of the Mallard the 

 mesoptiles are completely suppressed, but in the remaining two — 

 the ninth from the middle line at each side — the mesoptile is 

 represented by a simple tube from 10 to 12 mm. in length ex- 

 tending between the protoptile calamus and the tip of the tail- 

 quill. This tube, though complete to stai-t with, sooner or 

 later splits into two or more bands, the outer of which is con- 

 tinuous with the rhachis of the tail-quill, while the inner ends in 

 the rhachis of a vestigial tail-quill aftershaft. As these bands 

 have no barbules they evidently do not represent barbs. Though 

 there are only vestiges of two tail-quill mesojDtiles in the Mallard, 

 there are sometimes vestiges of all the mesoptiles in cross-bred 



