E. LÖNNRERG, ON THE RHAMPHOTHECA OF BIRDS. 511 



rostrale and a lateral labial on either side. In most Wood- 

 peckers a feathered strip extends from behind on the lower 

 rhamphotheca showing the boundaries of the infralabial and 

 the submandibular. But this is not all, for in some specimens 

 of Piciis martius, Dryotomus pileatus among others the limits 

 of the infralabial are fully conspicuous from the feathered 

 tract to the free mandibular margin of the rhamphotheca. 



Fig. 13. The bill of Campophihis. 



In the Passeriformes the rhamphotheca appears to be 

 quite simple. In the adult bird it seems also as if the 

 rostrale should form almost the whole upper and the mental e 

 the whole lower rhamphotheca. The small feathered strip, 

 described above from the Woodpeekers and others, is, however, 

 of ten present at the base of the lower rhamphotheca and 

 hints at the presence, although in a reduced state, of an infra- 

 labial and a submandibular. Traces of a suture defining the 

 labial may also sometimes be seen for instance in some Icte- 

 riäce (Cassicus a. o.). More seldom the suture between the 

 labial and the rostral is fully pronounced along its whole 

 extent in some lower Passeriformes. I have noted this in 

 specimens of Cymborhynclius macrorJiynchiis for instance. 



The labial and infralabial elements are, however, in these 

 birds small and little developed. They have in fact sufFered 

 a reduction in the adult. In the young Passeriformes (and 

 at least many C or a cii formes) the labials and infralabials 

 are present in the shape of the often yellow fringes 

 which börder the gape of the youngs. When the bird 

 grows, however, and its bill gets prolonged and assumes its 

 definitive shape this is, at least chiefly, effected by the in- 

 crease of rostrale and mental e and the underlying parts 

 covered by these shields, while the basal (labial and infra- 

 labial) elements get more or less completely reduced. The 

 development of the bill of the Passeriformes shows therefore 



Arkiv för zoologi. Band 1. 37 



