AXIAL SKELETON OE THE STEUTHIONID^. 41 



ness of their tubercula compared with their capitula, in harmony with excessive projection 

 of the diapophysial processes of the dorsal and dorso-lumbar vertebrae. They are also 

 quite exceptional in the number and great relative size of the uncinate processes which 

 they bear, and which are seven in number. The direction of their cui-vatures is much 

 as in Casuarius. 



Thejirst rib is much more slender and delicate than the others, even the last; but it 

 nevertheless bears a large uncinate process. 



The second and third lengthen and broaden, and also bear large uncinate processes. 



The fourth. Jiff h, and sixth ribs are the broadest, and the sixth is also the longest, of 

 the ribs. In common with the seventh, they support large uncinate processes. 



The eighth and ninth ribs are devoid of any such process ; but the ninth (and last) 

 rib is both much longer and much thicker than is the first. 



THE STERNAL RIBS. 



These ribs increase pretty regularly in length as we proceed postaxiad. They are all 

 slender in A. australis; but in Ji. owenii the fourth is considerably broadened out, and 

 the fifth rib is very much so. Nevertheless the breadth of these sternal ribs is not 

 nearly so great as is that of the vertebral ribs they join. 



THE STERNUM. 



The sternum of the Apteryx diff'ers very greatly from that of any other living genus 

 of the StruthionidcE ; it is so short, so broad, and so thin, dorso-ventrally, at its costal 

 margins. The coracoid-grooves are very short, small, and very far apart, while the 

 preaxial margin of the sternum between them, far from presenting any median pro- 

 cess, is strongly concave. The costal angles are short, and continued from the dorsal 

 lip of each coracoid-gi-oove. The pleurostea are very narrow, and bear four small arti- 

 cular surfaces for the sternal ribs. Postaxially the sternum exhibits a very long median 

 process separated by two notches from the about equally projecting lateral xiphoid 

 processes. 



VERTEBRAL PARTS AND PROCESSES. 



The skeletal features in Apteryx much resemble those of Casuarius ; but the rugosity 

 of the spinal region is augmented by the great development of the diapophysial pro- 

 cesses and lamellae and the large hyperapophyses and catapophyses, the latter sometimes 

 forming a subvertebral ring. The skeleton of Apteryx, however, is at once distinguish- 

 able by the very broad ribs, the numerous and large uncinate processes, the greatly and 

 equally extended (axially) trunk-spines, the absent supratrochanteric processes, and the 

 depressed (ventrad) sacro-caudal vertebrae. It is also distinguisiiable by its short and 

 broad sternum, with very thin pleurosteon, and having a concave preaxial margin and 

 three long postaxial xiphoid processes. 



VOL. X. — PART I. No. 6. — March, 1877. g 



