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21. .-1 Revision of the Reptiles of the Karroo. By E. BROOM, M.D., 



D.Sc., F.B.S.S.Af. 



PROBABLY no fossiliferos deposit in the world will ever compare in 

 importance with the extensive Permian, Triassic, and Jurassic beds 

 forming the Karroo system of South Africa. We have here the 

 continuous record of perhaps 3,000,000 years, and as they were the 

 years which saw the birth of all the various reptilian orders, of 

 the birds and of the mammals, the most important years in the 

 world's history. 



Though a large number of species are known, and though we have 

 a very good idea of the general character of the fauna at different 

 periods, the known species must be few in number in comparison to 

 those which remain to be discovered. 



In the last ten years the number of known types has been more 

 than doubled, and one feels compelled from time to time to stop and 

 take stock lest one gets overwhelmed with the multitude of forms. 



In the following lists I have endeavoured to classify all the known 

 reptiles of the Karroo. For many years it will be impossible to be 

 certain of the validity of a few species founded on very imperfect 

 remains. Fortunately most South African workers have been careful 

 only to found species on skulls or good skeletal remains, and hence 

 the confusion caused so frequently in America and Europe by having 

 names given to vertebrae or limb bones scarcely exists with us, and 

 the few such types as there are will be treated as they deserve to be. 



As an Order can rarely, if ever, be as carefully defined when first 

 proposed as a species or genus, it is impossible to apply the rules of 

 nomenclature to the large groups. Doubtless it is right to com- 

 memorate the work of the pioneers by using the names proposed by 

 them wherever possible, but it is quite impossible always to do so 

 without causing hopeless confusion. For example, the name Cotylo- 

 sauria was proposed by Cope in 1880 as a suborder of which 

 Diadectes was the type. It was founded on an error and was given 

 up. In 1889 it was re-established as an order to include the reptiles 

 with roofed temporal regions. In 1888, however, Seeley had proposed 

 the order Pareiasauria, and there has been much discussion and 



