N. GYLDENSTOLPE, HEEL-PADS IN CERTAIN BIRDS. 15 



rest and placed in circular rows, the largest being situated 

 in the middle. The whole pad measures 3,7 mm in length. 

 Mr. Seth Smith writes in his accoiint of the heel-pads in 

 Selenidera maculirostris Licht. that »it is noteworthy that no 

 such pads are found in the Parrots» (Proc. Zool. Soc. London 

 1913, p. 1095). As seen by the specimen of Melopsittacvs 

 undulatus Shaw. examined, the remains of a heel-pad occurs, 

 but these pads are not f urnished with any pointed tubercles, 

 as is the case among the Turnakeets, Barbets and Wood- 

 peckers. This may perhaps be explained by the fact that 

 even the very young specimens of Parrots use their strong 

 bill when moving about in the nest-holes, which also seems 

 to be the case with the species of the Strigidce nesting in 

 holes, and in which a heel-pad of similar shape and structure 

 as those found among the Bucerotidce has been noticed. In 

 such cases it seems to be unnecessary for the young birds 

 to use the metatarsal joint as a locomotive organ, and 

 therefore no real pad has been developed. 



Tryckt den 24 juli 1917. 



Uppsala 1917. Almqvist & Wlksells Boktryckeri-A.-B. 



