150 



BR. R. BROOM ON THE 



The most primitive known tarsus of the lizard-like group is 

 that of Brooraia perplexa Watson. Though the top of the skull of 

 this animal is unknown, almost all the rest of the structure is 

 known, and fortunately the tarsus is almost perfectly preserved. 

 As in the large majority of early reptiles, there are two large 

 proximal elements. There are five distal tarsals and two other 

 small elements. The two proximal elements have the usual 

 foramen between them, and are doubtless the fibulare and inter- 

 medium. The two small elements are regarded by Watson as 

 the first and second centralia. I regard the inner one as the 

 imperfectly ossified tibiale. The distal end of the tibia as found 

 is in a position to articulate with what I regard as the cartila- 

 ginous position of the tibiale. Watson, in his restoration, shifts 

 the tibia to make it articulate with the intermedium, which he 

 regards as the fused intermedium and tibiale. If we articulate 

 the tibia as Watson has done, the three first digits seem 

 practically without any proximal support — a condition which 



Text-figure 13. 



Text-fieure 14. 



Text-figure 15. 



Text-fig. 13. — Right tarsus and metatarsus of PalaoJiatteria longicaudata Credner. 

 A primitive Permian reptile of doubtful affinity. Regarded by Williston, 

 Watson, and others as a Theropsidan : by the writer and others as an early 

 Sauropsidan. After Jaekel. 



A cartilaginous tibiale was probably present. 



Text-fig. 14. — Right tarsus and metatarsus of MLvosaurus nordensJcjoldi Hulke. 

 A Triassic Ichthyosaur. After Wiman. 



Text-fig. 15. — Right tarsus and metatarsus of Steveosternum tumidum Cope. 

 A Lower Permian Mesosaurian. After M'Gregor. 



seems very improbable. The second small element is doubtless, as 

 Watson holds, a centrale. I give a figure of the tarsus as found, 

 as restored by Watson, and as I am inclined to restore it (text- 

 figs. 16-18). 



There is another primitive reptile which one wishes one knew 

 more about. I refer to JPalceohalteria longicaudata Credner. 

 Though first described over thirty years ago, and apparently 

 known by very satisfactory and nearly complete skeletons, we are 

 still in much doubt about the animal and its affinities. For many 

 years it was believed by every one to be a primitive two-arched 



