SHUFELDT. ] OSTEOLOGY OF THE EREMOPHILA. 649 
- non-pneumatic, no apertures having been discovered to allow the air 
access to the interior. 
A fibular ridge, 4 millimetres long and 1 millimetre deep, is developed 
in the upper third of the shaft, perpendicular to its outer aspect, for the 
lower articulation of that bone. : 
Huxley and Gegenbaur maintain that the distal extremity of the 
tibia represents the astragalus among the Class Aves, and there certainly 
seems to be some foundation for this assertion, for if we examine this 
bone in the young of any of the Galline, as in Centrocercus, we find the 
segment that eventually ossifies with this end of the tibia to be rather 
too extensive for a mere epiphysis, and may represent that tarsal bone. 
This joint is more thoroughly discussed in the osteology of the Tetra- 
onide, further on. Without further remark, then, upon this important 
and still unsettled question here, we will observe that in Hremophila, 
and in all birds, the leg-bone terminates distally by two anteriorly placed 
condyles, separated by a well-defined intercondyloid notch. These con- 
dyles, approaching each other behind, diverging in front, are reniform 
in outline and shape, with their convex surfaces downwards. They are 
higher on the shaft anteriorly, and the articular portion is more exten- 
sive. Likewise, anteriorly the shaft is grooved below, to be bridged over 
just above the notch by a narrow bony span, arched outwardly, that holds 
the tendons of the deep extensors in position. 
The inner end of this arch is the higher on the bone, and just above 
it, on the shaft, we find a minute tubercle, that gives attachment to a lig- 
ament that is extended to another tubercle lower down on the shaft, and 
on the opposite side. 
The fibula is the merest apology for a bone, represented only by a 
slender spine on the outer side of the tibia. It has a superior and knob- 
like head, that articulates with the horizontally expanded head of its 
sizaple companion; lower down it meets the fibular ridge, and is firmly 
attached to it by a strong, fibrous, and close-fitting connection. 
Below the ridge the fibula is continued, hair-like in dimensions, to meet 
the tibia below the middle of the shaft, to become thoroughly and indis- 
tinguishably confluent with it. 
The patella (Pl. IV, Fig. 22) is a free bone, and is found in the tendon 
of the quadriceps extensor. It is compressed antero-posteriorly, with 
an elliptical base above. From the points representing the vertices of 
the major axis of this ellipse, bounding lines pass, to meet broadly con- 
eave below. The anterior surface, limited by these boundaries, is con- 
vex outwards; the posterior surface, slightly concave, is divided by a 
vertical ridge into two unequal parts, the outer of which is the greater. 
The femur averages 2 centimetres in length, the tibia 3.2 centime- 
tres, and the bone now to be described as the tarso-metatarsus nearly 
2.3 centimetres. 
The metatarsals of the second, third, and fourth toes, and certain tar- 
sals at the upper extremity of the bone, coalescing, form the segment, 
tarso-metatarsus, next in order below the tibia, with which it articulates. 
The articular surface of its summit is so arranged as to accommodate 
itself to the condyles of the tibia, consisting essentially of an inner and 
outer antero-posterior facet, and a prominent spine on the anterior mar- 
gin, that accurately fits in the intercondyloid notch of the bone above. 
On the posterior aspect of the bone above we find the *‘calcaneal” 
process, here approaching a right parallelopiped in form, being vertically 
pierced by four minute cylindrical canals, two next the shaft and two 
parallel with them and above. They are for flexor tendons, which pass 
through them. The shaft is straight, subcylindrical, and hollow, ex- 
