220 ME. W. P. PTCEAFT ON THE MORPHOLOGY AND 



Apteryx, in the form and position of its coracoid grooves, resembles Rhea more 

 closely than any other group. Like Rhea they are widely separated by a deeply 

 concave median portion of the anterior border of the sternal plate. The groove lies at 

 the base of the anterior lateral process. It is very short, and has a conspicuously 

 projecting lower lip. 



The sternal plate differs from that of all the foregoing in being non-pneumatic. 

 Its breadth exceeds its length. Posterior lateral processes are well marked, and 

 divided one from another and a median process by a pair of notches. The articular 

 surfaces for the ribs, as in Struthio, extend along the greater part of the lateral 

 sternal wall. 



Occasionally, e. g., in an A. austrab's described by Owen, the sternum was fensterated. 

 Beddard descrilies a pair in A. australis mantelU. In another of this species were a 

 pair " of pin-hole size." 



Parker directs attention to a distinct keel on the sterna of A. australis mantelli. 

 As Beddard remarks, tliough not easy to see, this is readily felt. He found traces in 

 A. haastii, and I think to these we might add A. oweni. A similar keel, and much 

 more easily seen, often occurs on the sterna of Struthio. 



The researches of T. J. Parker and Beddard, which I am able to confirm, show that 

 no really reliable specific characters can be obtained from the sternum of Apteryx. 



Roughly, as Parker and Beddard point out, " in A. australis the length of the 

 corpus sterni appears to be constantly more than half its breadth." 



In A. australis mantelli " the length of the corpus sterni is — often considerably — 

 less than half its breadth." 



In A, oweni " the length of the body is less than half its breadth." 



A. haastii, according to Beddard, belongs to the same category as the last two. 



The emargination of the anterior border of the sternal plate and the length of the 

 metasternal and posterior lateral processes vary so much that they cannot be relied 

 upon as specific characters. 



The anterior emargination of the sternum seems to offer at least one more or less 

 constant character. Thus, both Parker and Beddard agree that this is usually a 

 semicii'cular incision, but that A. atistralis mantelli may be distinguished " from 

 A. australis by the greater depth of the emargination in the former subspecies." 

 Mr. Beddard finds at least one exception to this, in A. a^istralis mantelli. Parker 

 points out that " in A. oweni .... the emargination of the anterior border is slightly 

 sinuous, each side presenting a sigmoid curvature." There would appear to be no 

 exceptions to this rule. 



The sternum of Dinornithidce more closely resembles that of Apteryx than of any 

 other form herein described. From this it differs in the following points : — That 

 portion of the anterior border of the sternal plate which separates the coracoid grooves 

 in Apteryx is in the present group perfectly straight instead of hollow. Furthermore, 



