SHUFELDT.] OSTEOLOGY OF THE CATHARTIDA. 783 
18 brought tangent to the lowest point in either condyle, so as to include 
them both, it will be seen that the axis of the shaft is nearly perpen- 
dicular to such a surface, showing that the outer condylar tuberosity to 
be but very little lower than the inner, not nearly so much so as in some 
birds. 
The patella in these Vultures is of fair size, and bears out its most 
common ornithie characters, being more or less flat superiorly, convex 
in front, and divided into two unequal faces behind, the inner being 
the larger; it is situated well above the cnemial crest of tibia in the 
tendon of the quadriceps femoris. 
Quite an intimate union exists between tibia and fibula, although pos- 
itive anchylosis never takes place, along the produced and prominent 
fibular ridge on the outer aspect of the shaft of the tibia, occupying a 
good share of the upper third of this bone. Above this point the fibula 
is very much enlarged, and drawn backwards into a laterally compressed 
tuberous head, with a smooth, nearly horizontal facet above, that in none 
of the species rises much above the summit of the articular surface of 
its companion. Below the fibular ridge this bone dwindles to its usual 
styliform dimensions, being compressed from before, backwards, and 
running well down the tibial shaft into its lower third, to terminate 
in a free pointed end, in all of the Cathartide, except Cathartes aura, 
though the union is very intimate at the lower extremity in the skeleton 
of Sarcorhamphus. The tibia has a large cuboid head, but the undulat- 
ing articular surface at its summit is not profoundly impressed by con- 
dy ‘lar depressions, for the trochlez of the femur, and, indeed, the pro- 
and ecto-cnemial ridges are but feebly developed ; "the latter is produced 
fibularwards as a strong though blunt tuberosity, shielding the superior 
tibio-fibular articulation infront. The eremial crest above these processes 
is likewise low and not raised to any extent above the general articular 
surface to which it forms the anterior boundary. 
A section of the tibial shaft, made anywhere between the distal ex- 
tremity and the fibular ridge, shows it to be broadly elliptical, and the 
entire shaft is bent so as to be convex anteriorly, concave throughout 
its length posteriorly; it expands transversely as it approaches the dis- 
tal extremity, where we find the usual points for examination found in 
the vast majority of the class. A broad and strong osseous bridge is 
thrown obliquely across the groove that is the continuation upwards of 
the intercondyloid notch, to retain the extensor tendons. The trochlez 
are reniform in outline, placed in antero-posterior and nearly parallel 
planes, the fibular one being the broadest anteriorly; the notch Sepa- 
rating them is deepest just below the bony bridge for the extensors in 
front, while behind it is not carried very far up the shaft and becomes 
very shallow, the trochlez apparently running into one common surface. 
The bones of the leg of Neophron percnopterus are very similar to those 
found in the Cathartide ; the principal differences seem to be that the 
pro- and ecto-enemial ridges at the proximal extremity and the trochlez 
at the distal are placed rather farther apart; the bony span to hold the 
extensor tendons is the same. _We mention this fact because in some of 
our American Hawks (Tinnunculus, Polyborus) it is found to be double, 
i. €., the bridge above is thrown across a wider tendinal groove in these 
birds, and from the lower margin of the span another. bony piece is 
joined that is carried down to the inter-condyloid notch. This arrange- 
ment gives one opening above and two below, one on either side of the 
last bony span mentioned. 
Unfortunately we will not be able to enter into the subject of the tarsal 
segments, and their mode of union to the bone we are now about to 
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