ARKIV FÖR ZOOLOGI. BAND 11. NIO 12. 



Fam. Picidae. 



In the Ibis 1909, p. 619, the late Mr. C. Stonham figured 

 and described a peculiar structure found in the young of tbe 

 Green Woodpecker (Picus viridis viridis Linn.). The spe- 

 cimen on which Mr. Stonham founded his description was 

 quite young, almost new hatched, and it is therefore of a great 

 interest, that a similar structure also occurs in young birds 

 which have already left the nest for a long time. As shown 



Fig. 11. 



Picus viridis viridis Linn, Lateral 



view of left tarsus. V^' 



Fig. 12. 



Picus viridis viridis Linn. 



Left tarsus. V^- 



by a series of young Green Woodpeckers in the collections 

 of the Royal Natural History Museum of Stockholm a similar 

 structure is also present in specimens which are quite able 

 to fly. The sharp conical tubercles found in very young 

 specimens are, however, obsolete, though the presence of a 

 well-developed pad is still visible. As in the Capitonidce the 

 dermal papillae are placed in more or less regular rows. The 

 whole pad is, however, composed of a much larger number 

 of tubercles than in that family, though they are of the same 

 shape and general appearance. Tn Picus viridis viridis Linn. 

 they are about 45 in number and the largest and strongest 



