214 Shufeldt on the Osteology of C inclus Mexicanus. 
pressing as many of the technicalities in terms, as is compatible 
with exactness, and in accord with the tastes of those who have 
not devoted themselves especially to anatomical reading and 
work. 
In studying the skeletons of birds, or of anything else for that 
matter, the student must keep the fact ever present in his mind, 
that the great value of such studies and the descriptions that may 
follow them, rests almost entirely upon the comparisons that he 
makes ; the more carefully and minutely he compares the form he 
may have under consideration with nearly related forms, the 
greater will be the value of his results ; to this end tend all the 
studies of biologists of the present day. 
With respect to the skull of Cinclus, our space will not per- 
mit us to enter upon the engaging part of the subject as to the 
mode of formation of this part of the skeleton in the adult 
from the many segments found in the cranium of the chick, it 
being enough for us to say that the usual bones ossify, unite, and 
leave the ordinary ones free, as the pterygoids, the ossa quadrata, 
and the lower jaw. The superior mandible is drawn out into a 
sharp point, and the bony nostril on either side occupies con- 
siderable space, being long and elliptical in outline ; as in all 
nearly related genera these apertures are not separated by a bony 
partition or septum, but below we detect a delicate vomer in the 
median plane. 
The eye-cavities or orbits are well shut off from the nasal 
chambers beyond them by broad bony walls composed of the 
usual elements, and here each is of a quadrate figure, as seen in 
so many genera of birds. The upper and outer angles of these 
osseous partitions are rounded. The almost complete separation 
existing between the two cavities just referred to by no means 
exists between the orbits themselves, for here we find an extreme- 
ly deficient septum, and a large aperture leading into the brain- 
case at the usual site of the exit of the nasal nerves, the openings 
for the optic nerves being circular and entire. 
On the inferior aspect of the skull we find maxillo-palatines, 
of a more or less spongy composition, existing between maxilla- 
ries and the delicate palatines, which latter are slightly bent down- 
wards from the horizontal plane. The pterygoids are very 
slender, and articulate in the usual manner with the quadrates 
and the palatines. 
