510 ARKIV FÖR ZOOLOGI. BAND 1. 



of a nasal. In many birds of these two groups the cere has, 

 so to say, advanced still further on the way to reduction 

 or degeneration so that it has become feathered and thus in 

 quality approaches the common integument. This shows, I 

 mean, the general mode of development and indicates how 

 the horny »reptilian» plates, when they are not useful 

 any longer for the bird and therefore can be reduc- 

 ed, first become degenerated into a soft »cere» which 

 then by and by is encroached upon by feathers and 

 finally assumes the same qualities as the common 

 skin. 



Among the Cuculi the bill appears to be quite simple, 

 but a closer examination of the rhamphotheca of different 

 Cuckoos will soon make probable that although the rostrale 

 forms the most part of the upper rhamphotheca a labial in 

 a more or less developed state is present below and behind 

 the nostril. Sometimes it seems to be pretty well defined. 

 In the Musophagidce a labial on either side may be seen. 

 In Schizorhis a groove from the nostril and backwards forms 

 a part of the upper börder. 



Among the Coracice indications of a compound bill may 

 be seen in many Alcedinidce in which the labial often is 

 discernible. 



That the upper rhamphotheca of the Bucerotidce is com- 

 pound is often plainly visible. A well defined casque might 

 be interpreted as an excessive development of the internasal. 

 But even in birds with less exaggerated bilis as in Lojoho- 

 ceros a boundary-line between a median unpaired rostrale and 

 a lateral labial on either side may be seen. 



The longitudinal grooves of the rhamphotheca of TJpupa 

 indicate, no doubt, on the upper jaw a division in rostrale 

 and labials, and on the lower in infralabial and submandi- 

 bular shields. A feathered strip projecting on the sides of 

 the lower jaw of Irrisor has a similar meaning. 



Among the Capitonidce and allies the compound state 

 of the bill is still better pronounced. In a couple of speci- 

 mens of Megalcema corvina I find the infralabial completely 

 defined and in several specimens of the genus Trachyphonus 

 labial as well as infralabial elements are tolerably distinct. 



In most "Woodpeckers, at least all large forms, but many 

 small as well, the upper rhamphotheca is divided in a median 



