620 



PROF. J. COSSAR EWART ON THE 



The calamus of the protoptiles is strong and rigid and firmly 

 fixed to the expanded tip of the tail-quill rhachis. By way of 

 strengthening the connection between the protoptile and the tail - 

 quill, four or more pairs of the terminal barbs of the tail-quill 

 are attached to the protoptile calamus (text-fig. 6). At the end 

 of the second week the " nestling " tail and the other structures 

 concerned are sufficiently developed to admit of young Mallards 



Text-figure 7. 



The proximal portion of the calamus of a tail-quill protoptile containing " cones."" 

 As the calamus approaches the tip of the tail-quill it splits into an outer 

 portion continuous with the expanded rhachis of the quill and a more slender 

 inner portion continuous with a vestigial tail-quill aftersliaft. c, protoptile 

 calamus with "cones." sh., tail-quill shaft, af., vestige of tail-quill after- 

 shaft. 



obtaining the greater part of their food by diving*. Notwith- 

 standing the loss of the protoptiles during the sixth week, young 

 Mallards usually continue to behave like diving ducks up to the 

 end of the eighth week. From what has been said it is evident 

 that the " nestling tail " of the Mallard duckling is not from first 

 to last entirely composed of nestling feathers. It is a true 

 nestling tail up to the middle of the second week, but from the 



* Two of nine Mallard ducklings I had under observation began to dive on the- 

 thirteenth day : they were all diving on the fourteenth day. 



