THE TRIAS OE GRAAFF EEINET, S. AFRICA. 421 



The ungual phalanx is broad, subobtuse ; in length 1 J inch, in 

 breadth 1 inch 2 lines, that of the articular surface being 11 lines. 

 The phalanx supporting the ungual one is 9 lines in length and 1 

 inch 3 lines in greatest breadth, its proportions being nearly those 

 of the second phalanx of the fifth digit in the Dicynoclon (?) above 

 cited. The pair of convexities near the distal end of this phalanx 

 indicate the bicondylar trochlea. The outer surface is abraded from 

 the preserved distal end of the first or proximal phalanx. This 

 digit, which I take to be the fifth or ulnar one of Plati/podosaurus, 

 is relatively shorter and thicker than in the Dicynoclon (?) cited. 



Of the next (fourth) digit (iv) a smaller fragment of the proximal 

 phalanx is preserved. The second phalanx, 2, seems to have been 

 one inch in length and the same in breadth. The ungual phalanx, 

 3, is 1 inch 7 lines in length, 1 inch 1 line in breadth ; but all these 

 phalanges have suffered abrasion of the exposed (dorsal or anconal) 

 surface. The third digit (iii.) is represented by the ungual, 3, and 

 a small part of the second phalanx ; the former is 1 inch 9 lines 

 in length and 1 inch 5 lines in breadth. The second digit (ii) loses 

 size ; its ungual phalanx, 3, is 1 inch 4 lines long, 1 inch 1 line 

 broad. Of the first or radial digit there is no trace ; nor would the 

 portion of matrix supporting the above-described bone be big 

 enough to have preserved any trace of it had it existed. 



Each of the ungual phalanges are slightly deflected. The digits 

 have formed part of the left fore foot. The breadth of this paw, if, 

 as is most probable, it was pentadactyle (as in the subject of pi. lii. 

 fig. 2, 0/9. c'dr), may have been 8 inches. Prom the relative length 

 of the second phalanges of the fourth and fifth digits compared with 

 those of the above subject, the paw oi Platypodosaiirus seems to have 

 }yeQn somewhat shorter in proportion to the breadth. The ungual 

 phalanges are more obtuse -, the terminal angle is less produced. The 

 claws they supported appear to have been adapted rather for 

 fossorial work than for prehension or laceration of a struggling prey. 



Though relatively shorter, the ungual phalanges have more the 

 proportions of those of Echidna than of Ornitliorhynclius ; they difier 

 still more from the homologous phalanges in the smaller Cape 

 reptile (fig. 5). 



Femur. — At the time (1876) of the publication of the Catalogue 

 of South- African Fossil Reptilia I had but insufficient data for a de- 

 scription of the femur in any species. A proximal portion of that 

 bone in Pareiasaurusf (PL XVII. fig. 8) affords, however, a few 

 characters for comparison with the femur of Platypodosaurus. The 

 trace or impression of the hind limb in Saurosternon indicates the 

 femur to be somewhat slender and a little longer than the 

 humerus. In Saurosternon GrieshacliiiX it is one third longer and 

 there is a trace of a " third trochanter " projecting slightly from the 

 inner surface of the shaft ; but no such trace is shown in the speci- 

 men of S. Bainii. 



* On this hypothesis the ungual phalanx of the innermost or first digit, i, 

 is added in outline to those in fig. 4. 



t Op. cit. p. 13. t Th. n. 8S. 111. K-x. fio-. 4. 



