STUDIES OF THE MACROOHIEES. 



337 



both, on the other hand, are extremely unlike the pectoral girdle 

 as we find it in Geococcyx. 



These remarks apply with equal truth and force to the pectoral 

 and 'pelvic liiiibs of the several forms under examination ; and 

 even iq the case of the reversion of the toes in Trogon and the 

 Ground-Cuckoo, we are all aware that in the former bird the 

 second toe is turned back, while in the latter it is the fourth 

 one that is reversed. 



I agree entirely with Professor W. K. Parker when he 

 states that " the familiar term ' zygodactyle ' for birds with a 

 certain form of foot has been very useful; and yet how much 

 ignorance it may be made to hide ! It seems to be something 

 when one knows that a certain bird belongs to that group ; and 

 yet a Cuckoo, a Parrot, and a Woodpecker come none the nearer 

 each other zoologically by the possession of that kind of foot "*. 



To recapitulate then, and judging from the sheleto7is alone, w^e 

 must see that such a form as Geococcyx californianus is more or 

 less remotely related to such birds as Alcedo and Dacelo, 

 perhaps much nearer them than it is to the true Tree-Cuckoos. 

 In snying this I am aware that in a paper recently read for me 

 before the Zoological Society I was still inclined to support 

 the classification of Garrod, who divided the Cuculidce into two 

 subfamilies, viz. the Ground-Cuckoos {Centropodince) and the 

 true Cuckoos (Cucidince) (P. Z. S. 1874, p. 121) ; and this paper 

 of mine referred to the anatomy of G. californianus, but at the 

 time I had no specimens of true Cuckoos to compare it with. 

 Still I am inclined to adhere to that opinion until I have had an 

 opportunity of making further researches into the structure of 

 many other types more or less nearly related. On the face of it 

 I should be disposed to think that Geococcyx, so far as its skele- 

 ton is concerned, came nearer to such a form as Dacelo gigantea 

 than to Cuculus canorus, for instance, notwithstanding the 

 structure of the foot. But many of these interrelated groups 

 are exceedingly puzzling, and still require a considerable amount 

 of original investigation of their morphology. 



Of the Caprimulgi, of course, I shall have more to say further 

 on ; it is very evident, so far as their osteology indicates, that 

 they are very widely separated from the Trogons. 



And now as to the Trogons themselves, still being guided by 



^ Parker, W. K., " On the Morphology of the Skull in the Woodpeckers 

 and Wrynecks," Trans. Linn. Soc, Zool. 2nd ser. vol. i. pp. 1-22. 



