SKELETON OF PHORORHACOS INFLATUS. 81 
the groove for the extensor tendons nearly median, there is no distinct tuberosity 
at the outer side of the extensor bridge, and the condyles are comparatively small 
and separated by a broad intercondylar gorge; while, in correlation with the small 
size of the intercondylar tuberosity of the metacarpus, there is no depression at the 
upper end of the intercondylar groove, into which it fits when the bones are flexed 
one upon another. 
The dimensions of the tibio-tarsus are :— 
cm. 
Lei, MAG ClineE GeOnrhGEN 6 o 6 G6 o a 0 9 a 0 0 Ff 6 6, oss 
5 Wants caserellYotcins. 6 o oo co Oo eo 0 \0lwm 6 oF «ave 
_ Width at distalend . . . . eee oo . a) 3 
Width of shaft at narrowest points i. e. about 3 cm. above extensor ioridiee: 27 
(Chiron inthis pone 6 o Oo o og a 8 co b oo oO oF tee 
Width from front to back at same point . ... +, ..=. =... «20 
The Metatarsus. (Plate XVII. figs. 11-17.) 
The glenoidal facets for articulation with the tibia are deeply concave ; the outer (0.) 
is slightly below the inner, and has a bluntly pointed process on its outer border. 
There is a prominent rounded intercondylar process (7.¢c.), which on the outer side, 
at its base, bears a shallow pit for the insertion of the outer semicircular ligament. . 
On the outer side of the bone, immediately below the anterior angle of the outer 
glenoid facet, is a rough surface for the insertion of the lateral tibio-tarsal ligament. 
Posteriorly the hypotarsus (hy.) forms a broad projecting mass, consisting of an 
outer broad ridge and a narrow inner one, separated by a shallow groove; the outer 
and inner surfaces of the hypotarsus are also slightly grooved, but there are no closed 
or nearly closed channels for tendons. The whole hypotarsus is short, and the two 
ridges constituting it converge below into a simple median ridge, which soon dies 
away on the hinder surface of the shaft. In the slight depressions on either side 
of the hypotarsus are the posterior openings of the interosseous foramina, the inner 
being slightly higher up than the outer. 
The anterior face of the shaft is deeply concave in its upper part, so that the 
interosseous foramina open anteriorly at the bottom of a deep fossa, the outer a little 
above the inner. Immediately below these foramina is a pair of oval rugosities, the 
outer slightly above the inner, for the insertion of the tibialis anticus. Internal to 
these is a deep groove, over which the inner border of the bone forms an overhanging 
lip; this groove is for the tendon of the extensor communis digitorum. 
The concavity of the upper portion of the anterior face is continued as a broad 
channel extending down about the upper half of the shaft; but there is no specimen 
in which this region is complete, so that the exact length of the bone is unknown. 
The posterior surface is occupied at its upper end by a ridge forming a prolongation 
nN2 
