520 STRUCTURE AND CLASSIFICATION OF BIRDS 



struthious birds, with the exception of the adult cassowary 

 and the Dinornithidae, the ossified ethmoid appears on the 

 dorsal surface of the skull between the nasals. In the adult 

 the sutures disappear, and the bones are so firmly united 

 that the quadrate and the columella are the only movable 

 bones in the skull. The quadrate has a two-headed otic 

 process, differing so far from other struthious birds and 

 agreeing with the Carinatae. 



PAEKEK'S statements as to this matter are opposed to 

 those of FUEBEINGEE in the table of differential characters 

 which he gives in his great work. The vertebral column is 

 described by the authors already quoted as well as by 

 MIVAET.' There are sixteen cervical vertebra, and four ribs 

 articulate with the sternum. The atlas is either perforated 

 or only notched by the odontoid process, and it is imperfectly 

 joined above, not always, but in many cases, at the summit 

 of the neural arch. The tenth and eleventh vertebra have 

 sometimes a ventral hypapophysial canal, as in Herodiones. 

 MIVAET found this to be the case with A. Oweni. I found 

 the catapophyses to approach each other very closely in 

 that species and in A. australis, but not to fuse. 



The sternum is somewhat variable in form. Occasionally 

 the posterior lateral processes exceed the middle process in 

 length ; sometimes they are less or subequal. As a rule the 

 sternum appears to be broader than long, but this is not 

 invariably the case. The varying proportions of the sternum 

 and the lengths of its several processes seem to offer cha- 

 racters diagnostic of the species. In two specimens of A. 

 Bulleri PAEKEE found a ' low ridge nearly as well marked as 

 the vestigial keel of Stringops.'' The shoulder girdle, like the 

 sternum, is subject to great individual variation. The relative 

 lengths of the scapula and coracoid vary ; the curve of the 

 scapula varies, but it is in the coracoid that the most inte- 

 resting variations occur. The coracoid notch, converted by a 

 ligament into a foramen, but being in the embryo a distinct 

 foramen in the cartilage, is sometimes absent, its place being 



1 ' On the Axial Skeleton of the Struthionidse,' Trans. Z. S. vol. x. p. 1. 

 See also ALLIS, ' On the Skeleton of the Apteryx,' J. Linn. Soc. 1873, p. 523. 



