An almost Perfect Skeleton of Pareiasaurus serridens. 135 



The Tibia and Fibula. 



The tibia and fibula are perfect. If allowance be made for a 

 slight degree of crushing in the tibia of the described skeleton of 

 P. haini, no appreciable difference can be observed between it and 

 the tibia of the present skeleton. The tibia measures in greatest 

 length •256m., and the upper end is •153m. in greatest breadth. The 

 lower end is •120m. broad. 



The fibula, which is entire, measures •258m., or a shade more 

 than the tibia. It is a moderately straight bone, expanded at each 

 end, and so similar are the two ends that there is some doubt as to 

 which is the upper and which the lower. The one end is rather 

 larger than the other, and it is probably the larger end that is the 

 lower. If in P. haini the part of the fibula preserved is the lower 

 end, as believed, then it is moderately certain that it is the larger end 

 that is the lower. The supposed lower end measures •082m. in 

 width, and the upper end -OTOm. 



The Large Tarsal Element. 



The large tarsal element is very similar to that found in P. haini. 

 A large foramen appears to enter near the middle of the front of the 

 bone just underneath the articulation for the fibula, and to come out 

 behind about the centre of the bone. This bone probably is the 

 united tibiale, intermedium, and fibulare. 



Concluding Observations. 



In considering the peculiarities of the limb bones of Pareiasaurus, 

 it is unfortunate that practically nothing is known of the limb bones 

 of those primitive reptiles that seem to be most nearly related to 

 Pareiasaurus, such as Elginia, Pariotichus, Pantylus and Chilonyx ; 

 and those primitive reptiles in which the limb bones are known, such 

 as Procolophon, the Anomodonts, the Theriodonts, and the Pelyco- 

 saurians, are probably not very nearly related to it. 



The vertebras of Pareiasaurus differ greatly from those of the 

 Anomodonts and the Theriodonts, and do not resemble very much 

 those of Pelycosaurians. There is, however, a distinct resemblance 

 seen in the vertebrae of ProcolopJion, though the vertebrae in 

 Procoloplion differ in being notochordal. 



The shoulder girdle of Pareiasaurus is probably essentially similar 



