South African Fossil Reptiles mid Amphibia. 167 



The foramen jugulare lies below the level of the foramen magnuni and 

 looks downwards and backwards. 



The palatal area is long and narrow, the basisphenoid region short 

 and broad. The minimum width across the pterygoids is under 4 mm. 

 There is a small but distinct transpalatine. 



Types. Two skulls in nodule. (S.A. Mus. Cat. Nos. 3526, 3526a.) 



Locality. Harrismith, O.F.S. 



Horizon. Middle Beaufort Beds. (Lystrosaurus zone.) 



GENUS PKOLYSTROSAURTJS, gen. nov. 



PROLYSTROSAURUS NATALENSIS, gen. et sp. nov. 



A skull from Loskop, Natal, is made the type of this new form. 

 It was found in beds of undoubted Middle Beaufort age associated 

 with typical skulls of Lystrosaurus. Details of the skeleton are obtain- 

 able from an almost complete specimen discovered by Dr. du Toit also 

 at Loskop, the skull of which is slightly smaller and slightly different 

 in shape from the type. Nevertheless, it is advisable to put the two 

 specimens in the same species. 



The skull is intermediate in form between the normal Dicynodon 

 and the normal Lystrosaurus. The snout is bent down as in the latter 

 genus but is not elongated to anything like the same extent. The 

 interorbital region is broad, the intertemporal narrower. The nostril 

 is large and the distance between it and the orbit short. The temporal 

 openings are comparatively hrger than in Lijstrosaurus. The pineal 

 foramen is oval, as in Dicynodon. 



The following table gives the chief measurements of the skulls of 

 the two specimens. It is probable that the type has been slightly 

 flattened laterally. 



Type. Co-type. 



Greatest length (front of snout to squamosal) . 110 mm. 118 mm. 

 Greatest width . . 85 ,, 105 ,, 



Interorbital width 35 ,. 43 ,, 



Intertemporal width . 22 ,, 23 ,, 



Length of orbit . . . . 36 ., 38 ,, 



Height of orbit 21 ,. 26 



Height of suborbital border above edge of 



maxilla ... 41 ,, 45 



Width between tusks 30 33 



Length from snout to front of pineal foramen . 57 ., 57 ,, 



The chief features of the skull can be seen from the figures given. 



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