BY C. W. DE VIS. 447 



In D. patricius the plantar perforation is exceedingly small, not 

 greater than the diameter of an ordinary pin, and this is situated 

 close to the edge of the intertrochlear surface ; the descending 

 digital division of the artery passes along a deep canaliculate 

 groove not roofed in by bone. D. patricius presents a middle 

 term as to this point of structure between the living emu and 

 the bird represented by the fossil under notice, for in the last 

 there exists no trace whatever either of the plantar canal or 

 of tunnel or groove for the descending branch of the artery. 

 Possibly the bird should on this account be generically dis- 

 tinguished from Dromaius, but its separation, before we are 

 better acquainted with it, would hardly be prudent. Unfortu- 

 nately, the fossil is in a very imperfect condition ; the outer 

 trochlea is broken off close to the shaft, of the inner trochlea 

 there only remains a portion, and the lateral ridges of the mesial 

 trochlea are abraded. In addition to the absence of the arterial 

 canal, inferior size, a sensible anteroposterior compression of the 

 shaft, and a disproportionate length and tenuity of the mesial 

 trochlea are the features which chiefly differentiate the fossil from 

 the bone of the recent bird. The last two characters suggest the 

 name gracilipes for the species. From the table of measurements 

 appended it will be seen that in D. patricius this part of the leg 

 was larger in almost all its dimensions than it is in the living- 

 species. The exceptional agreement which obtains in the width 

 of the mesial trochlea, showing relative narrowness of that part, 

 is a specific character ; so also is the comparatively parallel direc- 

 tion of the lateral ridges of this trochlea, as they run proximad on 

 the anterior aspect of the bone, maintaining the breadth of the 

 pulley nearly to the junction of the process with the shaft. On 

 the other hand, the measurements of D. gracilipes are all less than 

 those of D. novce-hollandice, with the exception of that of the body 

 of the mesial trochlea ; taken from centre to centre of the lateral 

 depressions, this width is as much greater as the thickness of the 

 shaft is less. As far as we can judge from this fragment, D. 

 gracilipes was not only inferior in size to the living bird, but, on 

 the whole, was more attenuated in the proportions of its limb. 



