ANKLE. 85 



ligaments, and the different character of the upper and 

 lower parts for adapting a convex to a flat surface. 0. C. 

 266. Hunterian. 



B. 182. Small portion of the articular end of a femur. The 

 cartilage has been broken, it shows a vertical striation of 

 the fractured surface due to the cells being mostly dis- 

 posed in vertical rows. A thin layer of the free surface 

 projects, the cells being flattened and in horizontal layers. 

 0. 0. 267. Hunterian. 



William Hunter, Phil. Trans., vol. xlii. 1742-3, p. 514. 



Hammar, Arch. f. Mikr. Anat., Bd. xliii. 1894, p. 813. 



ANKLE. 



B. 183. The tendons and ligaments of the joint between the 

 tibio-tarsus and tarso-metatarsus of an Ostrich ; the thick- 

 ened tendon has been removed to show the interarticular 

 cartilage at the back part of the joint. 0. C. 275 A. 



B. 184. Right ankle-joint of a Duck-billed Platypus (Ornitho- 

 rhynchus anatinus) . The internal malleolus of the tibia is 

 strongly developed and articulates by an outwardly turned 

 rounded head with a deep pit on the inner surface of the 

 astragalus an arrangement strikingly similar to the peg 

 and socket articulation between the fibula and astragalus 

 in the Sloths. 



The tibio- and fibulo-tarsal joints are entirely separated 

 from one another by an antero-posterior synovial partition. 



B. 185. Right ankle-joint of an Opossum (Didelphys marsupialis}. 

 There is a well-marked semilunar interarticular cartilage 

 between the fibula and astragalus. It is attached in front 

 to the astragalus, behind to the fibula. 



B. 186. Left ankle-joint of a Tasmanian Devil (Sarcophilus 

 [Dasyurus] ursinus). An interarticular fibre-cartilage is 

 interposed between the fibula and astragalus. The natural 

 irregularities in the posterior margin of the tibio-fibular 

 articular surface are equalised by two nodules of bone 

 imbedded in the posterior ligament. 



