D)\ R. Broom — Discovery of a Karoo llammaL 345 



a new order — the Theroceplialia — for the primitive Theriodonts. 

 There are many other points of difference between the two groups 

 which I have dealt with in the paper above referred to. 



Not improbably the Theriodonts proper are descended from the 

 Therocephalians, but the gap between the two is probably as great as 

 between Parasuchians such as Phytosaurus and the Crocodiles. 



III. — On the Lower Jaw of a small Mammal from the Karoo 

 Beds of Ariwal North, South Africa. 



By R. Broom, M.D., B.Sc, C.M.Z.S. 



N the collection of Mr. Alfred Brown, of Ariwal North, which 

 I had recently the pleasure of looking over, I came across the 

 right lower jaw of a small mammal which Mr. Brown had discovered 

 in sandstone near Ariwal. Though unfortunately the teeth are lost, 

 there is evidence of there having been a large canine. The most 

 remarkable character of the jaw is its extreme shortness, and in its 

 general proportions it agrees much more with the jaws of some of 

 the small carnivorous Eutherians than with those of the small 

 carnivorous or insectivorous genera already known from the 

 Secondary rocks. The angle is well developed and but very 

 slightly inflected. The condyle is practically in a line with the 

 alveolar margin. 



Lower Jaw of Karoomys Broivni, Xat. size. 



In the absence of the teeth it is impossible to say much regarding 

 the affinities of the genus. It is not improbable, however, that it is 

 a member of the primitive mammalian group which gave rise to the 

 Marsupials on one hand and the Eutherians on the other. Its nearest 

 known allies are probably to be found among the Jurassic forms 

 such as Diplocynodon or Docodon. 



I propose to call the new form Karoomys Browni, after the 

 discoverer, who has already enriched science by the discovery of 

 so many new forms. 



IV. — The Minerals of some South African Granites.' 

 By F. P. Mennell, F.G.S., Curator of the Rhodesia Museum, Bulawayo. 



PLUTONIC rocks of acid composition are very extensively 

 developed in Africa south of the Equatoi'. These rocks 

 present many features of interest, and, especially under the 

 microscope, many minerals may be recognized besides the usual 

 quartz, felspar, and ferromagnesian constituents. Thus the granite 



1" Read before the South African Association for the Advancement of Science, 

 April 28th, 1903. 



