Reviews — Reptilian Fauna of the Karroo System. 229 



A Keview of the Reptilian Fauna op the Karroo System of 

 South Africa. By S. H. Haughton. Trans. Geol. Soc. 

 South Africa, vol. xxii, 1919, pp. 1-25, with 4 figs. 



"]\/rANY of the reptiles described in this paper are of unusual 

 ^'-'- interest, as they are forms identical with or closely similar 

 to the progenitors of the mammals. The general nature of the 

 reptilian fauna in each of the principal series of the Karroo system 

 (namely the Dwyka, Ecca, Beaufort, and Stormberg) is described, 

 and then the relationships of the Karroo reptiles are discussed. The 

 author traces the changes which occur as we pass from the primitive 

 Pareiasaunis to the much more mammal-like animals represented 

 by the Theriodonta. In the former the bones of the back of the 

 mandible are well developed, but as we pass upwards we find a gradual 

 reduction in the bones of this region and a corresponding enlargement 

 of the dentary, which in mammals comes to articulate with the 

 squamosal. Meanwhile the palatal portions of the premaxilla and 

 maxilla become enlarged, and each bone meets its neighbour in 

 the middle line, just as occurs in mammals. Furthermore, it is 

 shown that the changes which took place were not always in the 

 direction of increased specialization, since the teeth in Endothiodoyi 

 are all molar, the incisors and canines having been lost, while in 

 Prodicynodon and Diaelurodon the incisors alone have been lost. 

 There can be no doubt, however, that all these genera are derived from 

 forms which had a typical heterodont dentition, like mammals. 

 The author believes that the '" law of irreversible evolution ", 

 whereby an organ once lost can never be regained, though it may be 

 replaced functionally by another organ, is a principle of universal 

 application, but why the jjossibility of reversion followed by 

 persistence due to survival value should be ruled out is difficult 

 to see. Indeed, the results of modern breeding experiments are not 

 always in conformity with this so-called " law " or " principle ". 

 The paper is of great interest to the student of evolutionism. 



F. H. A. M. 



Notes on the Pleistocene Fossils obtained from Kancho la 



Brea Asphalt Pits. Los Angeles County Museum of History, 



Science, and Art, Department of Natural Sciences, Miscellaneous 



Publications, No. 2. pp. 3-5, with 22 figures. Los Angeles, 1918. 



rpmS paper contains figures and descriptions of various fossil 



^ mammals of interest : of these the skeleton of the Imperial 



Elephant, which was 3| feet higher than any known modern 



specimen of Elephas, and that of the pi-ehistoric Camel, an animal 



which, like the horse, originated in North America and then 



became extinct there, are specially noteworthy. 



The skeletons of the animals which were trapped in the asphalt 

 beds of Rancho la Brea and preserved in the oil are very remarkable, 

 and it is interesting to note that the same process is going on at the 



