THE RAZORBILL AND GUILLEMOT 25 



razorbills for some hours without seeing the sitting bird once fed. 1 

 Perhaps the practice of individual birds varies. 



The young are hatched after about 25-30 days' incubation. It 

 has been noted by Mr. Pycraft that, in the case of both, the second 

 or "mesoptyle" generation of prepennse (down feathers replaced 

 later by contour feathers 2 is not only much less degenerate in struc- 

 ture than the first or "protoptyle" generation, but in coloration 

 exactly resembles the summer dress of the adults, the resemblance 

 extending, in the case of the razorbill, even to the white stripe in 

 front of the eye. This fact supports Mr. Pycraft's contention that 

 the "mesoptyle" down is a degenerate ancestral plumage, though 

 less degenerate than is usually the case. 



The young remain on the ledges from three to four weeks, where 

 they are fed assiduously by both parents on small fish. The guillemot 

 brings one at a time, holding it lengthwise in the beak, with the tail 

 projecting about an inch and hanging over to one side. The razorbill 

 holds its prey across the bill ; it is, therefore, able to bring more than 

 one fish, and does so half a dozen at a time, the heads and tails 

 forming a fringe on either side. This marked difference between 

 the habits of the two species will be dealt with further in the chapter 

 on the puffin, which carries its fish in the same way as the razorbill. 3 



In pursuing their prey under the water both species use their 

 wings. They have the appearance of flying under the water, the legs 

 trailing behind, and used only though about this I am not certain 

 to help in turning. The resemblance of flight under the water to that 

 in the air is only superficial. The difference is thus stated by J. B. 

 Pettigrew : " In aerial flight the most effective stroke is delivered 

 downwards and forwards by the under, concave or biting surface of the 

 wing, which is turned in this direction ; the less effective stroke being 

 delivered in an upward and forward direction by the upper, convex or 



1 The same is the experience of a writer in the Annals of Scottish Natural History, 1904, 22. 



2 Vol. i. p. 15. 



3 The curious fact, hitherto unnoticed, that the razorbill, like the puffin, sheds part of its 

 bill in winter, will be treated in the same chapter (p. 52). 



VOL. III. D 



