144 STRUCTURE AND CLASSIFICATION OF BIRDS 



and some other Passerines, in which the bony opening of 

 the nostrils, although, as he figures it, rounded off at its 

 termination, ends behind, or at least on a level with, the 

 ends of the nasal processes of the premaxillse. In the same 

 way an intermediate condition is offered by Thinocorus and 

 Glareola, in which there is much the same kind of arrange- 

 ment. But one of the most striking instances which have 

 come to my personal knowledge is that of Chung a. Its 

 near ally Cariama is, as correctly stated by GAEROD and 

 others, holorhinal, which in view of its relationship to the 

 cranes is unfortunate. But in Chunga it is clear that the 

 holorhiny is secondary, being produced by a slight modifica- 

 tion of schizorhiny. 



A careful examination of Chunga shows that the two 

 parts of the nasal bone do not join evenly above the opening 

 of the nostril, but that the outer descending lamina of the 

 bone is divided for some little distance by a crack from the 

 premaxillary portion, the two running up in close contact- 

 so close that no actual space is left between them, only a 

 line of junction to mark their original separateness. In the 

 skulls of Cariama that I have examined there is no trace of 

 this ; but, considering the nearness to each other of the two 

 birds, it seems probable that it is merely disguised. This 

 fact favours FURBRINGER'S idea that schizorhiny is more 

 primitive than holorhiny, and is so far adverse to GARROD'S 

 view that ' the schizorhinal disposition is most certainly one 

 which is a secondary development upon the normal holo- 

 rhinal nares.' 



It is clear too that the holorhiny of such a bird as Opis- 

 thoconms, where the ossified alinasals produce the rounded 

 margin of the bony nostril, cannot be accurately compared 

 with the holorhinal nostril of a gallinaceous bird, where it is 

 the nasals themselves that bound the orifice. 



The presence or absence of basipterygoid processes is 

 another matter upon which some stress is usually laid from 

 a systematic point of view. One assumes that the existence 

 of these processes is the original condition and that their 

 loss is secondary. The presence or absence of basipterygoid 



