ARKIV FÖR ZOOLOGI. 



BAND 11. N:o 12. 



Notes on tlie lieel-pads in certaiii families 

 of Birds. 



By 

 NILS GYLDBNSTOLPB. 



With 16 figures in the text. 

 Communicated April 25th 1907 by E. Lönnberg and Y. Sjöstedt. 



In the Ibis 1890 p. 411—412 Doctor A. Gunther called 

 tttention to a peculiar structure on the foot of the yoiing 

 )f the common Wryneck {lynx torquilla Linn.). 



In these birds the skin on the heel is greatly thickened 

 md forms a prominent pad. The surface of this pad is 

 jovered with obtusely conical tubercles which Dr. Gunther 

 jonsiders as being dermal papillse. The occurrence of such 

 i pad is generally not very astonishing because the birds 

 lave the habit of resting on the heel when moving about in 

 :he nest hole. By being frequently used the skin on the 

 beel then by and by becomes more and more thickened until 

 a real pad is formed. In analogous cases a similar structure 

 Dften is to be met with in the animal kingdom. More pe- 

 ouliar is, however, the development of the conical tubercles 

 which are to be found on the surface of the pad. At an 

 early age these pads are most probably used when the young 

 birds are moving about in the nest holes. The older the 

 young bird grows, the more it is creeping about in the hole, 

 and it then does not only use its claws but pushes itself 

 forwards by means of the heel-pads with their rough surface. 



ArMv för zoologi. Band 11. K.-o 12. 1 



