147 
The pretrochanterian ridge (Pl. CVII. fig. 2, h) is linear, and may be traced down the 
middle of the fore part of the shaft; its continuation into the antentocondylar ridge (2) 
is interrupted, This ridge, as well as the antectocondylar ridge (ib. ib. m), is well 
marked, and relatively sharper than in Aguila. 'The rotular channel is broad and deep. 
The popliteal space (ib, fig. 1, z) is shallow. The distal end of the femur is relatively 
broader transversely than in Aguila. The intercondylar ridge (ib. fig. 4, ¢’) is well 
marked. The backward production of the inner condyle dividing the tibial facet (ib. 
ib. #) from the fibular facet (y'), is relatively more produced and sharper. Every cha- 
racter of the femur indicative of muscular force and strength of joint is better marked 
than in the smaller existing Raptorial birds, although inferior, especially as regards the 
posterior ridges of the shaft, or ‘linem aspere,’ to that bone in the huge objects of prey 
of the //arpagornis (Pls. XX.-XXIII.). The least circumference of the femoral shaft 
in the larger (female?) Harpagornis is 2 inches 6 lines, in the smaller (male ?) specimen 
2 inches 3 lines. The admeasurement in the Table, as in the subject in Pl. CVIL., 
is from the larger specimen of the extinct bird of prey. 
Tibia.—This bone in Harpagornis corresponds with the femur in its strength, ¢. ¢. in 
the proportions of breadth to length of shaft. 
The procnemial ridge (Pl. CVII. figs. 5 & 6, g) is more produced at its upper part 
than in the Eagles, but sooner subsides into the lower less prominent ridge (ib. fig. 6, 9’), 
which is continued down the fore part of the shaft, inclining toward the innermost of 
the distal condyles. The depression on each side of the procnemial ridge is well 
marked; the inner (tibial) one (ib. fig. 6, 7) is bounded by the low, thick, obtuse 
* entocnemial’ ridge (ib. ib. 0), extending from the overhanging inner (tibial) border of 
the proximal articular facet of that side of the head, obliquely downward and forward 
to join or be lost in the procnemial ridge. The outer depression (ib. fig. 5, 4) has the 
form of a wide vertical channel, and is bounded externally (fibulad) by the ectocnemial 
process (ib. ib. h). The fibular ridge (ib. fig. 5, m, m') is well marked; it is relatively 
more prominent, but is of minor longitudinal extent, than in the Hagles, ‘he ectar- 
ticular convexity is smoothly rounded; the rugous facet anterior to it for the ‘ crucial ’ 
ligament, and that attached to the head of the fibula, are well marked. ‘The two distal 
condyles (ib. fig. 5, ¢, s) show a breadth which exceeds by two fifths that of the same 
part. of the leg-bone in the Condor or Lammergeyer. In their proportions, shape, and 
degree of anterior conyexity these condyles exhibit the Falconine characters of this end 
of the tibia. The praecondylar groove (ib. ib. p) is crossed by the osseous bridge (q'), as 
in the ‘Diurnal’ division of Raptores. The strength of the ‘tibialis anticus’ muscle 
(p. 61, Pls. XI., XIV. s, Apteryz) is significantly indicated by the size of the bony canal 
which was traversed by its tendon. 
In the metatarsus (PL CVIL figs. 5, 6) of Llarpagornis the indications of the power 
of the raptorial foot reach their maximum. ‘This will be evident to any one comparing 
the above figures with those of the metatarsus of the Golden Eagle (Aquila chrysaetos). 
