338 
DR. R. W. SHUEELDt’s MORPHOLOGICAL 
the skeleton alone, it is very plain that they have no special 
affinity with the Trochili. 
When my eyes first fell upon the skeleton of one of these 
Trogons, as I have already stated, the remark was forced from 
me that they were “ Caprimulgine Cuckoos.” First impressions, 
hoAvever, are not always to be relied upon, for, apart from the 
general likenesses of their sterna, and having the same number 
of cervical vertebrae without ribs, from skull to pygostyle, and 
from pinion to pes, so far as the skeleton goes, Trogon mexicanus 
has nothing whatever to do with Geococcyx calif or nianus, and, as 
stated, I have no true Cuckoos to compare it with. I dare 
say that if related to the Cuckoos at all, it is more than likely 
to be nearer these latter in its osteology. I have not had the 
opportunity, as yet, to examine the skeletons of either Croto- 
phaga or Hey thr ops. 
Beyond a few apparent resemblances I find nothing in the 
skeleton of the Trogons that in any way points to their being re- 
lated, even remotely, to the order Caprimulgi ; and it seems to 
me that there must be a considerable gap between the Trogons 
and Kingfishers. 
The Anatomy oe certain Caprimulgi. 
Glancing at our list of material, we find that we have but a 
few American forms to illustrate the structure of this highly 
varied group of birds. There is an alcoholic specimen of the 
common Whip-poor-will, a couple of skeletons of the ISTuttall 
Poor- will, and several species of Chordeiles, both in alcohol and 
skeletons. 
In my first contribution in the P. Z. S., relative to the structure 
of the Caprimulgine types, I gave a very full account of the 
osteology of Chordeiles , with a number of figures, as well as a 
description of the skeleton of Nuttall’s Poor- will. I am con- 
vinced that when the hundred or more species composing this 
order come to be carefully examined as regards their structure, 
there will be not only some very good characters brought to 
light, but considerable difference found in the economy of the 
forms composing the group. 
Among the notable departures it will be remembered that in 
my first contribution to their structure I found the arrangement 
of the bones of the palate entirely different in the Nightjars and 
true Whip-poor-wills. 
