E. LÖNNBERG, ON THE RHAMPHOTHECA OF BIRDS. 505 



is only a step to such a one as that of the Grues. The 

 fusion of the elements has there proceded somewhat more, 

 but in a young Crane the different parts are well discern- 

 ible. 



On the bill of the Bustards (Otis) one may easily re- 

 cognize a rostrale and a pair of labials in the upper and a 

 mentale, a pair of infralabials and a pair of submandibulars 

 in the lower rhamphotheca. The submandibulars are rather 

 shorter than in other Gruiformes. 



Eurypyga lielias has evidently a median and a lateral 

 piece in the upper rhamphotheca and the covering of each 

 ramus of the lower jaw is by a longitudinal groove divided 

 in two shields one above the other and both confLuent with 

 each other and with the mentale anteriorly. The structure 

 of this bill is thus as in Aramus. 



In the interesting Poäica senegalensis the elements of the 

 upper rhamphotheca are well distinct showing the same pieces 

 as in Rails. The lower rhamphotheca is comparatively more 

 solid but the division in an upper infralabial and a lower 

 submandibular is quite discernible. 



Fig. 12. The bill of Stercorarius pomarinus. 



For the study of the bill of Laro-Limicolce the Skuas 1 

 offer the best material. In all specimens of Skuas which I 

 have examined for this communication I have found the bill 

 to be more or less plainly compound. If a specimen of 

 Stercorarius pomarinus or catarractes is chosen as an example 

 it may be compared with a Fulmarus glacialis. The hook 

 = rostrale is common to both. The narrow first labial of 

 Fulmarus has no corresponding feature in the Skuas, but 

 behind the rostrale there is in the latter a long labial cover- 

 ing the side of the upper jaw in a similar way as the second 

 labial does in the Fulmarus, and it is very shai-ply defined 



1 If they really belong there? 



