336 



DE. R. W. SHrrELDT's MOEPHOLOGICAL 



I place the just amount of weiglit that should attach to the 

 numher of these segments in the spinal column of any bird, I 

 think it should be borne in mind that these vertebrae are as 

 much entitled to be considered in the light of the special form 

 each or any of them may assume, as is any other part of the 

 skeleton. 



The day may yet come when the question of the exact affinity 

 of avian forms (or any other class of vertebrates for that matter) 

 will have arrived at such a point of refinement as to require 

 that even the morphology of each vertebra shall be known, to 

 assist us in correct decisions. In the table which I here 

 introduce (p. 335) the number of ribs and some few other points 

 which I deem it well to compare have been entered. 



So far as we are able to judge by a comparison of these, it 

 would seem that, taking into consideration the kind of data pre- 

 sented, Trogon comes nearer to Geococcycc in its vertebral column 

 than it does to any of the Caprimulgi. But it must be remem- 

 bered that it is really very difficult to discern any truly striking 

 resemblances among the vertebral columns of the several birds 

 under consideration. 



Turning to the pelves^ we find on comparing the pelvis of 

 Trogon with that bone as we find it in some of the Nightjars and 

 Whip-poor-wills, that there is a certain superficial likeness which 

 strikes us ; but when w^e descend to the comparison of details, we 

 are again met by the fact that these resemblances are purely 

 superficial. Of course neither the pelvis of CTiordeiles nor 

 Trogon reminds us in the least of the unique pelvis which so 

 conspicuously characterizes the skeleton of Geococcycc. How 

 they would compare with certain other Cuckoo-like birds I am 

 unable at present to say, from lack of proper material on which 

 to form an opinion. 



Passing to the sternum (and I have figured this bone for both 

 CJiordeiles and Geococcyx in my memoirs above referred to, 

 and for Trogon in the present paper), w^e are at once struck by 

 the resemblance between the sterna of Trogon and Geococcyx ; 

 the bones here are really very much alike, and both are 

 essentially different from the single-notched sternum of CJior- 

 deiles. 



Coming next to the shoulder -girdles, we are once more at 

 sea, for these parts not only have no special likeness to each 

 other, so far as Trogon and the Caprimulgi are concerned, but 



