48 IMi". l'"- 1^- J^eddard on the 



nut by any moans uiiuutc, of this groove for the reception 

 of a coiled trachea. I am disposed, therefore, to eouclude 

 that Balcurica is derived from a Crane that had a coiled 

 trachea and a corresponding deep excavation of the front 

 end of the sternnm. Now it is a point of some little im- 

 portance, in estimating the systematic position of Animus, to 

 compare the conditions to be seen in this particnlar region 

 of the bird with those observable in the Cranes. A glance 

 at the fiirure already referred to (fig. 3, p. 17) will shew 

 that in Animus the front end of the sternum is excavated in 

 the same way ; but the excavation is much shallower, though 

 even more extensive, than in Balearica. Furthermore, at 

 the anterior end of the excavation, just below the rudi- 

 mentary spina externa, is a deep hole (shown as a black circle 

 in the figures) which has its precise counterpart in Balearica, 

 though in the latter bird the hole in question is larger and 

 dee])cr. It cannot, I think, be doubted that \Ne have in this 

 Crane-like bird a vestige of a former condition, in which the 

 sternum was grooved and excavated in front for the reception 

 of the tracheal coil. Here, again, I do not lay any special 

 stress upon the likeness which Aramus bears in these pecu- 

 liarities of structure to Balearica. It is readily credible that 

 the tracheal coiling and the corresponding sternal excavation 

 may have been independently lost a dozen times ; but in 

 any case Loth birds have progressed along similar lines. 



Nor can I find any evidence that other Crane-like birds 

 have recently lost their tracheal coils and are therefore to be 

 looked upon so far as equally nearly allied forms of Gruine 

 birds. Jn Psophia, Cariama, Rhinochetus, and Honiara the 

 front end of the sternum — the region which is under 

 discussion — is, it is true, flattened, but it is not in the least 

 hollowed ; and if it were to be suggested that flattening 

 is simply a further, and not a large, exaggeration of the 

 slight hollowing to be found in Aramus, it might be replied 

 that in the birds mentioned the middle line of the region of the 

 steinum, with which we are at present concerned, is traversed 

 by a {[uite distinct ridge, which runs up to, and indeed up, 

 the spina externa. All these facts combine, in my ojjiuion. 



