NEW FOSSIL REPTILES. 



869 



but the palatal view shows that the tusk is differently placed and 

 relatively very much larger. 



The greatest length of the skull measured obliquely from the 

 snout to the back of the squamosal is 270 mm., and the greatest: 

 width across the squamosal is also 270 mm. 



The snout is very short and the nostrils completely roofed over 

 by the projecting nasals. The breadth across the nasals is 83 mm. 

 The premaxillary is broad and shallow. The maxilla is short and 

 also shallow. The tusk is large and situated right beneath the 

 orbit, and directed downwards. In diameter it measures 25 mm. 

 by 28 mm. at its base. The frontal region is broad and flat, the 

 narrowest part between the orbits being 63 mm. If there is a 

 distinct postfrontal it is very small. The parietal foramen is 

 large, measuring 15 mm. by 10 mm. The preparietal lies mainly 

 in front of it. The parietals are unusually large, and the posterior 

 branch of the postorbitals more slender than in most species. 

 The postorbital forms the front half of the long slender post- 

 orbital arch. The squamosal extends forwards below the post- 

 orbital arch and has a large articulation with the maxilla. The 

 pterygoids where they meet are broad and, except for the median 

 ridge, flat. Considering the great width of the skull the quadrates 

 are not far apart. 



The general structure of the skull will be better understood 

 from the illustrations given, 



DiCYNODON PSITTACOPS, sp. n. (PI. XCII. fig. 17.) 



In working at the troublesome genus Dicynodoii we have con- 

 stantly been in doubt as to whether the small Z>icynO(io?ispecimeiTS 

 are distinct species or only young animals. Frequently they agree 

 sufliciently in general shape and structure as to suggest the 

 probability of their being young specimens of Dicynodon 

 leoniceps or some other large species. But this is certainly not 

 always the case. Many specimens of Dicynodon joicberti are 

 known from the Pareiascmrics horizon and all small, while no 

 large Dicynodon is known to occur in the same zone. At Beaufort 

 West a considerable number of specimens of a small Dicynodon 

 also occurs, but there is no evidence of any large Dicynodon 

 having lived at the period. The large Anomodonts are the 

 Endothiodons. There is thus satisfactory evidence that the 

 common Dicynodon of the Beaufort West commonage is an adult 

 animal, and apparently a new species. The best specimens are a 

 good skull with much of the skeleton and a fairly good skull with 

 nearly the complete skeleton. I take the latter as the type. 

 Both specimens were obtained by Mr, J. H. Whaits. 



The greatest length of the type skull is 102 mm., and of the 

 second specimen 112 mm. The width of the type across the 

 squamosals is about 66 mm. Across the maxilla the maximum 

 width is 42 mm. The interorbital width is 20 mm., and the 

 intertemporal 18 mm. 



The following are the most noteworthy characteristics of the 

 Proc. Zool. Soc— 1912, No. LYIII. 58 



