638 



PROF. J. COSSAR EWART ON THE 



of them, in order to survive required a fur-like coat throughout 

 life we have no means of knowing ; but this much is certain, that 

 in most recent species of birds the mesoptile coat is in the act of 

 being suppressed, or has already disappeared — even in the King 

 Penguin chicks it is probably never worn in the Antarctic for 

 more than 9 or 10 months. From what we know about the 

 mesoptile coat it seems to have been originally produced partly 

 by lengthening the protoptiles and partly by the development of 



Text-figure 14. 



pb. 



mb. 



A developing' mesoptile of an Adelie Penguin. In penguins the inesoptiles consist; 

 as a rule, of numerous barbs which in some areas may reach a length of over 

 three inches. A true protoptile calamus containing " cones " though present 

 in ducks is seldom met with in other birds. As the protoptile is pushed from 

 the skin the inner ends of the protoptile barbs, destitute of barbules, separate 

 from each other and are subsequently seen to be continuous with mesoptile 

 barbs, mb., one of the nu.merous barbs of the developing mesoptile. pb., one 

 of the nine protoptile barbs, each of which is connected with a mesoptile barb. 

 b., one of the nine slender cords which together for a time playeu the part of a 

 protoptile calamus. 



new barbs. This is suggested by text-fig. 14, which represents a 

 developing mesoptile feather from the breast of an Adelie 

 Penguin. The nine barbs forming the protoptile are directly 

 continuous with nine mesoptile barbs ; the rest of the mesoptile 

 consists of barbs having no connection with the protoptile. As 

 Pycraft points out, the second coat of* the Adelie Penguin is "a 



