SHUFELDT.] * OSTEOLOGY OF THE SPEOTYTO. 617 
With the head it constitutes the articular surface for the pelvis—it be- 
ing opposed to the antitrochanterian facet of the ilium, while the caput 
femoris plays in the cotyloid ring. The excavation for the ligamentum 
teres on the latter is conical and deep, consuming a good part of the 
bone; it is situated on its upper and inner aspect. In looking into the 
relation existing among head, neck, and shaft of the femur of this bird, 
we must observe that if the straight line lying in the middle of the 
surface of the internal aspect of the shaft were produced upwards, it 
would pass through the centre of the facet at the summit—if anything, 
nearer the trochanterian ridge than it does to the head. This facet also 
is notably narrower just before arriving at the head than at any other 
point. Again, the plane passing through the external and circular bound- 
ary of the head makes an angle of a good 45° with this line, so that 
with these facts in view we can hardly assert in the case of the species 
before us, as do some authors on comparative anatomy in describing 
this bone in general, that the head of the femur is either nearly at 
right angles with or is sessile with the shaft. It would appear, though, 
that it has quite as much of a neck to boast of as the anatomical neck 
of humerus or the neck of the scapula in works on human anatomy. 
The shaft throughout its length, until it begins to approach the distal 
condyles, where it is subcompressed and expanded antero-posteriorly, 
is nearly cylindrical, bent slightly backwards at its lower end, and 
offers for examination merely the intermuscular ridges, with the linea 
aspera, feebly marked, and the nutrient foramen, all of which maintain 
their usual pesitions on the bone. At the distal extremity the rotular 
canal, the intercondyloid notch, and the popliteal fossa are all strongly 
produced, giving due prominence to the condyles, internal and external, 
between which they form the dividing tract. The external and lower 
condyle is divided in two by a vertical excavation, deepest above. Of 
the two facets thus formed, the inner articulates with the tibia, the 
outer with the head of the fibula. The external surface of this condyle 
is flat and continuous with the shaft. The inner condyle, broad poste- 
riorly, has a slight depression in the surface that bounds it on the tibial 
side, and as a rule the usual sites for ligamentous attachments about 
this extremity are at best but feebly represented. The patella, encased 
in the tendon of the quadriceps femoris, is situated about 3 millimetres 
above the rotular crest of the tibia, anteriorly, having the form of an 
oblate hemispheroid with its base directed upwards, the long diameter 
of which measures 3.5 millimetres. The tibia is the longest bone in this 
bird’s skeleton, and at the same time, taking this length into considera- 
tion, the least curved or bent along the shaft; it has, however, a slight 
and just appreciable gradual curvature forwards that is most apparent 
about the junction of middle and upper thirds. Its average length, 
measured on the inside, is 6.7 centimetres; its extremities being ex- 
panded for articulation, above with the femur, below with the tarso- 
metatarsus. These expansions are of about equal dimensions, though 
differing vastly in form, in this respect being unlike some of the diurnal 
Raptores, in which the distal condyles constitute the smaller end of the 
bone. 
Among the most important points presented for examination about 
the head is the articular surface that crowns it above for the condyles 
of the femur. This is subquadrate in form, uneven, highest at the in- 
ner and anterior angle, sloping gradually to the opposite one, bounded 
almost entirely around by a raised margin, that is most feebly devel- 
oped posteriorly, and at a point anterior to the head of the fibula, where 
it is absent. In front this border may be nominated the rotular or epi- 
