1889.] OF A THERIODONT REPTILE. 575 



the Monotremes, it is evident that the process marked a in Plate LV. 

 also represents the same. Further it is manifest that the process b 

 is the distal extremity of part of the preaxial border of the scapula, 

 which has become twisted from the line of the acromion towards the 

 dorsal aspect, this being most marked in Ptiichosiarjiim (fig, 2). 

 This dorsal torsion of the preaxial border of the sca[)ula is a very 

 remarkable feature, and appears to support Professor Flower's view 

 that the preaxial border of the Monotreme scapula represents the 

 spine of the scapula of the higher Mammals. Thus in the scapula 

 of Ftychosiagum the body of the bone has become to a great extent 

 three-sided, and the surface on the inner side of the preaxial border 

 would well represent the prescapular fossa of the higher mammals, 

 the portion on the outer side of the same the postscapular fossa, 

 and the somewhat rounded posterior surface (left side of figure) the 

 subscapular fossa. If, as seems most probable, we really have in 

 this type of scapula an indication how the reptilian scapula of the 

 Monotremes was modified into that of the higher mammal.--, and 

 the acromion is rightly identified, we shall further have to assume 

 that the acromial process also subsequently received a dorsal torsion, 

 so as to resume its original position at the distal extremity of the 

 preaxial border, now converted into the spine. 



After this long digression it will suffice to add that the scapula of 

 the form under consideration corresponds very closely to that 

 described as Platypodosaurus. 



The humerus is represented by the somewhat imperfect distal 

 half of that of the left side, a restored figure of which is given in 

 Plate LV. fig. 3, on a scale of one third. This specimen shows the 

 entepicondylar foramen underlying a bar situated in the usual position 

 on the palmar aspect of the shaft. The radial condyle is large and 

 well preserved, and above this there is the supinator flange on the 

 preaxial border which serves to distinguish the humerus of the 

 Theriodonts from that of the Dicynodonts. Unfortunately, however, 

 this flange is imperfect, so that it cannot be determined whether 

 there was an ectepicondyiar foramen. 



Compared with the Anomodont humeri in the British Museum 

 this specimen agrees very closely, both in size and contour, with the 

 cast of the corresponding portion of a left humerus from the Permian 

 of Russia described under the name of Brithopus \ The Russian 

 specimen (Plate LV. fig. 4) has been a good deal damaged, and its 

 radial condyle has been broken away ; but allowing for this imperfec- 

 tion the general resemblance between the two specimens is very close. 

 Trusting to this resemblance in the distal extremities of the two 

 humeri the proximal extremity of the African bone has been restored, 

 partly from a Russian specimen doubtless referable to Brithopus ", and 

 partly from the large African humerus figured in pi. xii, of Owen's 

 ' Catalogue,' as Parrasaurus, but which more probably belongs to 

 Tapinocephalus. The present specimen appears to be distinguished 



1 For synonymy, see Owen, Quart. Journ. Geol. Soc. vol. xxxii. p. 352 

 et seq. 



^ Vide Owen, loc. cit. 



