58 PHYSIOLOGICAL SERIES. 



is tilled in all adults by loose lenticular or irregular-shaped 

 bodies. Some are of minute size, but the great majority 

 have a uniform diameter of 2 mm. They consist of mucin, 

 fibrin, and branched cells. Those removed from this joint 

 are shown below : in bulk they measured between 6 and 

 7 c.c. 



B. 52. Portion of the skull with the right mandible of a Duck- 

 billed Platypus (Ornithorliynclnts anatimis). The temporo- 

 maxillary joint has been opened from the front, to show the 

 absence of any interarticular substance between the two 

 joint surfaces. The condyle of the mandible is convex and 

 laterally expanded, the corresponding glenoid cavity being 

 concave from side to side, convex from before backwards. 

 The movements of the jaws are probably very simple in 

 character. 



For Mammalian Joints. Parsons, Jour, of Anat. & 

 Physiol., vol. xxxiv. 1899, p. 41. 



B. 53. Right half of the skull of a Tasmanian Devil (Sarcopliilus 

 [Dasyurus] ur sinus) showing the temporo-maxillary joint. 

 The glenoid fossa, as in placental Carnivora,is deeply concave 

 from before backwards, with well- marked pre- and post- 

 glenoid processes. The condyle of the mandible is strongly 

 convex and fairly accurately fits the glenoid cavity. There 

 is no interarticular cartilage. 



B. 54. Part of the skull with the left mandible of an Armadillo 

 (Dasypus eexcinctus). The cavity of the temporo-maxillary 

 joint has been exposed from the outer side to show the 

 small size and simple flattened character of the articular 

 surfaces and the entire absence of any interarticular 

 cartilage. 



B. 55. A section through the temporal bone and condyle of the 

 lower jaw of a Beaver (Castor fiber), giving a posterior 

 view of the double articular cavity and intermediate sub- 

 stance ; and showing that the cupsular ligament between 

 the interarticular substance and glenoid cavity is longer 

 than that between the interarticular substance and condyle 



