352 Mr. W. P. Pycraft on the 



Rhamphotheca. — Simple. Nostrils impervious^ nearer the 

 base than the tip, and having a comparatively large, oval, 

 unprotected orifice. Along the rhamphotheca of both upper 

 and lower jaws^ on the inner side, a little removed from the 

 tomium, there runs a short ridge extending from the back of 

 the mouth forwards to a point corresponding with the an- 

 terior margin of the external nares ; this ridge supports a 

 row of horny cones, which are probably used for crushing the 

 fruit on which the bird largely lives*. 



Podotheca. — Scales on the acrotarsium large, reticulate, 

 on the acropodium shield-shaped. Planta granulated. 



Claws on the wing absent, on the feet moderately large. 



Sternal callosity. — This is an elliptical horny patch of skin 

 lying immediately over the sternal keel, and is apparently 

 due to the fact that this part of the body is applied to the 

 branch upon which the bird is resting : as will be seen in 

 PI. IX. fig. 3 {St.cal.), it is placed obliquely to the long axis 

 of the trunk^ hence is well adapted for this purpose. Such 

 a horny pad is rare amongst birds ; the Rhea and Ostrich 

 may be quoted as examples in which it occurs. 



Moulting. — According to Mr. Quelch (11) there is no 

 periodic moulting-season, but the feathers are renewed fit- 

 fully : that is to say, moulting goes on all the year round. 



II. Pterylosis of the Nestlings o/ Opisthocoraus. 

 (PI. X. figs. 1-3.) 



There are five nestlings exhibiting as many gradations in 

 the development of the plumage ; I shall therefore describe 

 them in five stages, remarking, however, only such particulars 

 as are of any importance. 



Pteryla. — So far as the distribution of the feathers is con- 

 cerned, a reference to the Plate will show that the pterylosis 

 of the nestling differs from that of the adult chiefly in that 

 the pteryla ven trails is continuous as far as the sternal 



* I have purposely deferred a more careful description until I have 

 made a thorough examination of the rhamphotheca in all stages of 

 development. 



