On the Manus and Pes of Pareiasaurus. 355 



By fitting the distal elements in position the complete structure of 

 the carpus can be seen, only the 1st centrale being lost, and its size 

 and position being apparent. 



The 2nd metacarpal is a large quadrangular bone, measuring about 

 42 mm. in length and 58 mm. in width. 



The 1st metacarpal is an irregularly shaped bone as shown in the 

 diagram. It measures 75 mm. in width and 46 mm. in greatest 

 length. 



The 1st phalanx of the 1st digit is a small bone measuring 56 mm. 

 in width and 26 mm. in length 



O 



The structure of the carpus will be seen to be of the primitive 

 generalised reptilian type. In the highly developed amphibian 



RIGHT PES OF Parcinsaurui. 



Eryops, the number of the elements is the same as in Pareia- 

 saurus, and the arrangement fairly similar. In Srjhenodon the same 

 primitive structure is retained with little modification, and in the 

 mammal-like reptiles the agreement is even more striking. In 

 Dicynodon we find the same 11 elements, and except for the smaller 

 size of the radiale the carpus might be called Pareiasaurian in type. 

 In the Dromasauria and the Pelycosauria the same type is met with, 

 and even in the mammals of to-day the only difference is that the 

 5th carpale and one of the centralia are lost, and often both 

 centralia. 



The pes, though lacking the proximal part of the tarsus, for- 

 tunately has the digits nearly complete, besides three distal 

 tarsal elements. 



The tarsals preserved are the 2nd, 3rd, and 4th. The 5th appears 

 to have been unossified. 



