SKELETON OF PHORORHACOS INFLATUS. 79 
marked by an intermuscular ridge running obliquely downward and inward from the 
outer edge of the trochanter: in its lower third it forks, one branch running to the 
upper anterior angle of each of the condyles ; in its upper portion this line no doubt 
separated the surfaces for the crurwus and the vastus eaternus. 
There is a deep popliteal fossa, which is separated by a prominent bar of bone from 
the intercondylar fossa, which is marked by two deep pits for ligaments. 
The outer condyle projects considerably below the inner; its fibular ridge is very 
prominent, and the surface fur the fibula slightly concave from side to side. On the 
lower end of the outer condyle is a very distinct facet for the tendon of the outer head 
of the tibialis anticus. Anteriorly the condyles project considerably, and the rotular 
channel is comparatively deep. 
Comparing the femur of Diomedea with the fossil, we find that it differs, among other 
points, in the shallowness and form of its popliteal fossa and in the great antero-lateral 
compression of the lower end of the shaft. The head, moreover, is much less distinctly 
pedunculate. 
The femur of Grus differs in the somewhat more curved shaft, the elevation of the 
trochanter above the head, the somewhat shallower popliteal fossa, and the smaller 
degree of obliquity of the distal articulation. 
In Psophia the trochanter is high and the popliteal fossa shallower than in the fossil. 
In Cariama the shaft is rather curved and the trochanter is somewhat raised above 
the head, which is very similar to that of the fossil: the distal end differs only in the 
somewhat greater shallowness of the popliteal fossa. 
In the Rails the shaft of the femur is always much curved, and the trochanter rises 
considerably above the head. 
In the Birds of Prey (including Serpentarius) the femur is pneumatic, the trochanter 
rises above the head, and the neck, as a rule, is very short. 
The dimensions of the femur are :— 
mm. 
Length ee rel ee aM Ree ; 227 
Winclingijesmellencl 6 ¢ o Glo Hip 0 a b Om 5 GU Oe 59 
ny eet GET OTC oN ie acid 20 Toe oo Po D4 oo Oc 62 
5 Olannble win 6 6 GMb io goo 0 Oo 5 0 5 Le 25 
Circumference of middle of shaft . . - » «© «© © + + * © # + 81 
The Tibio-tarsus. (Plate XVII. figs. 9 & 10.) 
The tibio-tarsus is a comparatively long and slender bone. The shaft is son.ewhat 
flattened on its anterior and posterior surfaces, and tapers slightly towards its distal end. 
It is straight, but the median border near its distal end curves slightly mward, so 
that the inner condyle projects considerably inward ; the outer condyle is ina line with 
the outer border of the shaft. he anterior surface is bordered internally by a strongly- 
marked linea aspera, which is continuous aboye with the procnemial crest, and towards 
VoL. xv.—Part 1. No. 4.— October, 1899. N 
