692 MR. F. G. PARSONS ON THE [June 16, 
fibular joint has anterior and posterior ligaments; its synovial 
cavity is in direct communication with the knee-joint. 
The Ankle-joint has feeble anterior and posterior as well as 
strong lateral ligaments. The internal lateral consists of a super- 
ficial and a deep portion; the former is a narrow flat band which 
passes from the back of the internal malleolus downward and 
forward to the navicular ; the deep is much broader and stronger 
and runs downward and backward from the anterior part of the 
side of the malleolus to the sustentaculum tali, forming an X with 
the superficial part. The external lateral ligament consists of 
three bundles—superficial, middle, and deep ; the superficial passes 
from the back of the external malleolus to the outer side of the 
calcaneum just behind the articulation with the cuboid ; the middle 
is thicker and stronger, and runs downward and backward from the 
anterior part of the malleolus to the prominent tuberosity on the 
outer side of the caleaneum, crossing the superficial bundle to form 
an X; the deep band runs almost directly backward from the 
posterior part of the malleolus to the outer side of the astragalus. 
Fig. 6. 
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Ankle-joint of Petrogale, from the inner side. 
In the Foot there are two calcaneo-cuboid ligaments, the outer 
of which is very strong and runs from the under surface of the 
caleaneum to the cuboid and on to the bases of the fourth and 
fifth metatarsals. The inner is much smaller and passes from the 
sustentaculum tali to the bases of the second and third metatarsals 
and slightly to the cuboid. As the inner longitudinal arch of the 
Kangaroo’s foot is not developed, the calcaneo-navicular ligament 
is not very strong. The mechanism of the Kangaroo’s foot is 
interesting, and I hope to deal with it more fully in a subsequent 
paper. 
