AXIAL SKELETOX OF THE STRUTHIONID.E. 



33 



THE STERNUM. 



STERNUM OF CAiSSOWABY (^ natural size). 

 Fig. 27. Fig. 28. 



Fig. 27. Ventral view. Fig. 28. Lateral view. 



This bone is exceedingly characteristic. It is very long, narrow, and boat-shaped 

 compared with that of the other Struthionidse. The costal angles are exceedingly short ; 

 and between the coracoid-grooves there is a very marked pit, which penetrates deeply 

 into the bone and is an exaggeration of that minute notch which exists, in Dyomceus, 

 upon the median process between the coracoid-grooves. It agrees with the sternum of 

 the last-named genus in not having any prominence on the ventral surface, and in 

 having neither the ventral surface so convex nor the dorsal surface so concave as are 

 these surfaces in Bhea. In all other respects it also agrees with the sternum of Lw- 

 mceus, except that the costal angles (as above indicated) are so much smaller, and that 

 the portion which is postaxial to the pleurosteon is more prolonged. 



VERTEBRAL PARTS AND PROCESSES. 



These skeletal features in Casuarius quite resemble those oiBrommus in those points 

 in which the latter have been said to differ from the vertebral parts and processes of 

 Rhea, except that the catapophyses continue to the seventeenth vertebra, and that a 

 bifurcating hypapophysis appears first at the eighteenth or third cervico-dorsal vertebra, 

 as also that the cervical processes may be three in number or may abort altogether. 



VOL. X. — PART I. No. 5. — March, 1877. J" 



