784 GEOLOGICAL SURVEY OF THE TERRITORIES 
describe, and to the distal end of the tibia, as this requires the skeletons 
of the very young of the subjects in hand, material that I unfortunately | 
do not possess. 
The study of the forms assumed by the process or processes at the — ; 
proximal and posterior aspect of the tarso-metatarsus is extremely inter- 
esting, and as important as many of the results are, the author is obliged 
to confine himself here to a hasty sketch of the general appearance of 
this tuberosity as it is found in the Cathartide and some of the Old World 
Vultures and the Falconide. Among all of the American Vultures it is 
a broad cuboidal process, placed at the extremity of the posterior aspect 
of the shaft, mesiad. It has leading away from it below a raised crest, 
that soon merges into the shaft, or the amalgamated mid-metatarsal. 
In Cathartes this processis sharply grooved ina vertical direction be- 
hind. This is also the case in Catharista; the King Vulture has the 
process broader transversely, the grooving shallower, with its outer and 
posterior margins slightly produced. This condition is still further 
advanced in the Condors, while upon turning to Neophron we observe 
that it has been earried still further, so much so that the mid-vertical 
groove is now a broad concavity and the lateral productions appear as 
separate and rounded processes. 
In Polyborus tharus it is a distinct, broad quadrate plate at right angles 
to the shaft. In Tinnunculus, this plate is not distinct, or rather it is 
carried far down the shaft to merge into it in the lower third; an in- 
termediate form between the last two is presented by Jiicrastur brachyp- 
terus. . 
Gypogeranus presents it very much the same as in Cathartes aura, 
only rather longer for its width, which is quite natural in this bird of 
a stilt-like tarso-metatarsus.. An instance of its being apparently 
double is seen in Buteo cooperi, one stout and quadrate lamelliform 
process, crowned by a transverse, subelliptical plate, standing promi- 
nently out from the fibular side of the bone, while absolutely separated 
from it on the tibial side we find a smaller though eminently distinct 
apophysis with its summit slightly bent outwards, the intervening sur- 
face being broad and only moderately concave between the two. Other 
Hawks also assume this form, as Circus. A tough piece of cartilage is 
placed over this process in the Cathartide, through which many of the 
flexor tendons pass. The summit of the bone presents two lateral con- 
cavities with a median anterior rounded tip, all for the accommodation, 
in the articulated skeleton, of the trochlez of the tibia. 
Horizontal sections made at almost any point of the shaft are more 
or less parallelogramic in outline, and this portion of the bone is mark- 
edly straight in all of these Vultures, for we know that in many of the 
Faleonide, and the condition is slightly observable in Neophron, that 
the tarso metatarsus is often more or less bent in the reverse direction of 
the tibia above. The shaft of this, the last long segment of the hinder 
limb, is very much scooped out on its anterior and upper surface; this 
disappears as we approach the distal end of the bone, where we find the 
large foramen for the anterior tibial artery occupying its usual site. Be- 
hind, the shaft is doubly grooved, in a longitudinal direction, markings 
that are about equally distinct throughout their course, each groove pass- 
ing down alongside the plate that was described as coming from the pro- 
cess at the upper and hind end of the bone. Two foramina pierce the 
bone at its upper part, appearing posteriorly on either side of the plate 
just mentioned. The three trochlear projections that terminate this 
bone distally are large and well separated from each other, the mid 
one being the largest, standing out in front of the others, and possesses 
