4 JOURNAL OF SCIENCE. 



5. In Carinatse the scapula and coracoid — the two chief bones of 

 the shoulder-girdle- -are large and set to one another at an angle 

 which is usually acute though it may rise to 106°. There is nearly 

 always a furcula or merry thought attached to a process of the 

 scapula called the acromion and to two processes of the coracoid, the 

 acrocoracoid or clavicular process and the procoracoid process. In 

 the Ratitaa the coracoid and scapular are small, fused together into a 

 single bone, and their long axes make an obtuse angle : the furcula 

 is either absent or greatly reduced and the acromion, acrocoracoid, 

 and procoracoid processes are reduced to mere insignificant tubercles. 



G. The quadrate, or bone by which the lower jaw articulates 

 with the skull, has a double head in Carinatse, a single head in Ratita?. 

 As it is single-headed also in embryo Carinatse thi^ character is 

 usually held to indicate the more primitive position of the Ratita?. 



7. In Ratify the hinder ends of the pterygoid bones of the skull 

 articulate with a pair of large basi-pterygoid processes which spring 

 from the body of the basi-sphenoid bone : in Carinata? the basi- 

 pterygoid processes are small, spring as a rule from the base of the 

 rostrum of the basi-sphenoid, not from the body of the bone, and 

 articulate with the pterygoids some distance from their posterior 

 ends. 



8. The vomer of Ratita} is a large broad bone : in Carinata? it is 

 usually small. 



Zoologists are agreed as to the origin of birds from some kind of 

 reptilian ancestor, but there are many differences of opinion as to the 

 relations of the two sub-classes. The older ornithologists considered 

 the whole of the Ratitse as an order (Cursores) equivalent not to the 

 whole of the Garinataa but to one of its subdivisions, such as Passeres, 

 Gallina?, &c. The view now generally adopted is that the Ratita? 

 include several orders, each of which, although containing only one 

 or two genera, is the zoological equivalent of an entire order of 

 Carinata?. This view is taken by, inter alia, Prof. A. Newton (Encyc. 

 Brit., Art. Ornithology) and Prof. Furbringer whose learned and 

 colossal work on the Morphology and Classification of Birds has 

 brought the results of all former workers to a focus and has provided 

 the student of the group with a critical summary of the entire 

 subject such as has never been attempted before. 



Taking, then, the Ratita? and Carinata? as fairly equivalent 

 groups the question arises what is their relation to one another? 

 There are three views taken by modern writers on this matter. 



1. The Ratita? represent an ancient type of birds derived from 

 flightless reptilian ancestors. According to this view the progenitors 

 of the group have never possessed the power of flight, and their 

 relations to the Carinata? may be expressed diagrammatically as 

 follows : — 



