118 SHUFELDT. [VOL. III. 
In front of the orbital cavity is a spongy bone of some size, 
which I described in my memoir upon the osteology of Speotyto 
as the /acrymal, and I still take it to be such, and believe the 
processes above referred to as the supraorbital processes, to be 
developments on the part of the frontal bones. Two skeletons 
of nestlings of Bubo virgintanus seem to indicate this: speci- 
mens kindly collected for me by Dr. W. S. Strode of Bernadotte, 
Ill.; though in these, these processes are exceedingly small. 
Among certain Hawks and Falcons the arrangement is very 
different ; for in such a species as Fako sparverius, for example, 
these processes are very long and conspicuous; but they are 
here the true lacrymals, and send down a descending process, 
which, in either one, reaches to the maxillary, and articulates 
with the entire outer margin of the pars plana. In this little 
Falcon no such bone exists as the lacrymal which I have 
described for Speotyto, its place being monopolized by this de- 
scending limb of the very differently constructed lacrymal in it, 
and to which I have just alluded. In such characters as these, 
then, we find truly a great difference between such species as 
our Burrowing Owl and the Sparrow Hawk. 
Removing the vault of the cranium, and breaking down the 
walls of the brain-case, here composed of very delicate tables 
and abundant open diploic tissue, we find the brain of a form 
common to many S¢rigid@,—the cerebral hemispheres large, 
smooth, and somewhat pear-shaped, mounting as they do con- 
siderably above the rather small cerebellum. The pineal body 
is of no great size, while the optic lobes, as well as the optic 
tracts, are situated in the deep excavation formed at the bottom 
of the cranial casket. All the cerebral nerves, including the 
first pair, are of mere thread-like proportions, as soon as they 
are given off from the brain mass; and, indeed, the medulla 
oblongata is of small calibre compared with the size of the 
bird. 
An interesting feature is seen at the side of the skull in 
Speotyto, where the tendon of the temporal muscle passes 
through a foramen, above the squamosal, on the way to its in- 
sertion upon the mandible. This arrangement does not exist in 
such species as Aszo wilsontanus nor Syrnium nebulosum ; the 
former of these, with a very different skull from the Burrowing 
Owl, has simply a minute notch devoted to the same purpose; 
