768 GEOLOGICAL SURVEY OF THE TERRITORIES. 
important a matter is this, that we feel sure that our reader will be glad 
to examine the cuts we present illustrating these points in representa- 
tive members of several of the families involved. The views are from 
an outer aspect of the joint in each case, showing the heads of the three 
bones of the scapular arch and the glenoid cavity. The bones are all 
lettered to correspond, and z directs attention to the furculum, @ to the 
scapula, and a to the coracoid. 
The figure in the upper left-hand corner is of Catharista atrata, the 
figure below is of Circus hudsonius; the remaining one is of Neophron 
percnopterus. : ‘ 
In Catharista we see the common plan for all of the Cathartide, in 
which the clavicular head simply rests against the inner side of the 
coracoidal capitulum, while on the other hand, in Neophron and Circus, 
as representatives of the Falconide, the coracoid is actually molded to 
receive a corresponded surface on the clavicles. 
Taken in consideration with other characters, we are compelled to 
regard this arrangement of the bones of the scapular arch as still 
another valuable and reliable character differentiating these birds from 
the Old World Vultures and still further establishing Professor Huxley’s 
sound classification, as far as the Cethartidw are concerned, in awarding 
them a family of their own. No one could be more disposed to draw 
family lines in birds with greater caution than the author, nor one more 
adverse to establish such lines upon any single set of characters, chosen 
either from points in external differences or internal structure; still 
such decided distinetions as this must have their due weight, occurring 
as it does, too, in a set of bones that, taken in connection with the 
sternum, have always been regarded by ornithologists the world over 
as containing some of the most distinctive features in the avian skeleton, 
and even carried by some to such unwise extremes as to be chosen for, 
and considered of sufficient importance to even construct and base a 
system of classification upon. 
The scapular arch in the Cathartide is far more constant in its char- 
acters than the sternum itself, a bone we will now consider; and it 
strikes us, aS we glance at the many specimens before us, still more 
forcibly how totally impossible it would be to take this segment alone 
as a criterion upon which to classify the class and yet have genera and 
species of known affinities arranged anything like approaching proper 
order. My views upon the value of such single characters coincide so 
well with those of Wallace, who so long ago as 1864 appreciated and 
recognized the truth of what we have been saying, that we give some 
of his sound remarks upon this subject: 
* * * No one can be more convinced than myself of the utility of osteology, and 
especially of the sternum, in the classification of birds, and I sincerely trust that this 
great work may be brought to a conclusion (referring to a paper of M. Blanchard’s). 
1 cannot, however, allow that osteological characters are an all-sufficing guide. Like 
every other character taken singly, osteology is a very uncertain and irregular test of 
affinity, and is, moreover, in almost every case accompanied by parallel external char- 
acters. Sometimes one, sometimes another part of the bird’s organization has varied 
more rapidly, so that one group exhibits the most striking constancy of a part which, 
in another group, is subject to extreme modifications. The sternum is no exception 
to this rule, and by following it alone we should make the greatest errors in classifi- 
cation. For example, the sterna of the Finches and the Flycatchers are scarcely dis- 
tinguishable, notwithstanding the great dissimilarity in almost every part of the struc- 
ture of these birds—their bills, their feet, their plumage, their habits, food, and 
digestive organs. On the other hand, the sterna of the several genera of the Caprimul- 
gidee differ from ea*h other more than do those of the most distinct families of the 
restricted Passeres. The Bee-eaters, the Barbets, and the Woodpeckers, again, are 
_ three very distitct families, which, in a classification founded upon all parts of a bird’s 
organization, cannot be brought in close contact; and yet, their sterna, according to 
