24 



nected above to the true patella, is about two inches and a half long, 

 and below is articulated with the upper surface of the tubercle of the 

 tibia, a synovial sac intervening between the two bones. The Haversian 

 gland is large, and contains cells of fluid fat. 



The tibio-metatarsal joint is also ginglymoid in structure, and the 

 two bones are united by the following ligaments : — 



Internal lateral arises from the upper and back part of the promi- 

 nence on the inner side of the lower end of the tibia. It passes down- 

 wards and forwards, to be inserted into the internal lateral ridge on the 

 metatarsus for about four inches. The deep internal lateral is anterior 

 to the last, and passes from the deep pit on the inner side of the tibia, 

 downwards and forwards, to the inner edge of the front of the meta- 

 tarsus. This ligament is twisted in the extended position, and straight- 

 ened as the limb becomes flexed. As this band slips over a prominent 

 ridge on the edge of the inner side of the tibia, it gives a spring to the 

 joint. The superficial external lateral ligament runs from the upper and 

 anterior part of the outer side of the tibia, downwards and backwards, 

 expanding, to be inserted into the posterior part of the outer edge of the 

 metatarsus. The deep external lateral ligament arises in a deep pit on 

 the outer side of the external malleolus, an inch below the last. It 

 passes downwards and forwards, expanding, to be attached to the an- 

 terior part of the metatarsus. A distinct posterior ligament exists, 

 covered by the great tendons lying in their sheath, which is attached 

 to the upper border of the metatarsus by strong fibrous slips. In front, 

 a convex fibrocartilaginous anterior ligament covers the joint, running 

 from the tibia to the metatarsus, fibrous on either side, and cartilaginous 

 in the centre, where it sends septa in between the various tendons. 



Posteriorly and externally a rhomboidal inter- articular cartilage is 

 observable, which is retained in its place by two bands — one anterior, 

 passing forwards, semilunar in shape, and attached to the front of the 

 metatarsus; another running backwards, shorter, and attached to the 

 posterior part of the notch between the condyles of the bone. This acts 

 in preventing over- extension of the joint, and in increasing its elas- 

 ticity. 



Respecting the osseous anatomy of the ostrich there are no novel 

 points of importance observable in either of our specimens. In the 

 pelvic arch the principal characteristic seems to be the prolongation into 

 lines of those parts which in most other animals are represented by 

 points, as is exemplified in the posterior inferior iliac spine, which is 

 described in the Appendix to " Todd's Cyclopaedia" as a separate sacro- 

 iliac element," also in the elongation of the rami of the ischium and 

 pubis. The lesser sciatic notch is also closed below and behind by a 

 bony connecting band between the ischiatic spine and tuberosity, so as 

 to be converted into a foramen through which the obturator tendon 

 winds. 



