128 Annals of the South African Mitseum. 



and of increasing the size of the genus, these have been given specific 

 rank. 



The question of the value of certain features as species indices is 

 one that is not of immediate moment. The root-idea underlying 

 descriptive work of this sort is to give an account of the variation 

 among the Auomodont reptiles so that we may obtain, if possible, 

 some idea of the lines upon which variation has taken place. For 

 this purpose it is better to take notice of small variations and to give 

 each different form a special name than to "lump" possibly different 

 animals together under the one name. It is probable that future work 

 may pi-ove many of our supposedly different forms to be the same ; 

 then these new names will have to disappear. But the special features 

 which each of them implies will remain, and the name will have served 

 its purpose. 



Moreover, another purpose is served by this division of species. A 

 genus so prolific in individuals as was Dicynodon and so abundant in 

 varieties forms a good genus for the purpose of zoning ; and it may be 

 that the few zones now known among the Beaufort Beds may be 

 increased and more accurately denned by the use of the species of 

 Dicijiwdon. Even now, only one or two " species " seem to pass from 

 any one zone into the next ; and it may be found that each form is 

 confined to a comparatively small thickness of strata. 



In the following pages reference is made mainly to such forms as 

 are represented in the collection of the South African Museum, but to 

 make the catalogue somewhat more complete the literature dealing with 

 other described forms is given, together with a brief description of the 

 tvpe, culled entirely from the original papers. In the absence of 

 facilities for seeing and studying these types mostly now in the 

 British Museum or in the American Museum of Natural History - 

 or of specimens which can be assigned to them, no conclusions have 

 been drawn as to their affinities with the forms which are more fully 

 discussed. 



GENUS DICYNODON, Owen. 



DICYNODON JOUBEBTI, Broom. 

 1905. Broom. Kec. Albany Mus., i, p. 331. 



This is apparently a well-marked species, while all the specimens in 

 the S.A.M. collection range in size between fairly narrow limits. The 

 skull is small, with fairly large orbits and comparatively broad inter- 

 orbital and interorbital and interfrontal regions which are roughly of 



