200 THE WORLD OF LIFE CHAP. 



spot, found that each of these nodules contained well-pre- 

 served fossils of extinct animals, which proved to be reptiles 

 of the very same group as those of South Africa. Some of 

 these nodules contained a skull ; others contained the whole 

 skeleton, these being sometimes eight feet long, and of strange 

 forms corresponding to the crushed or distorted body of the 

 animal. Thenceforth Professor Amalitzky devoted himself 

 to the work of exploration by the aid of a grant from the 

 Imperial Academy of St Petersburg. The nodules are 

 taken to Warsaw, where they are carefully opened, and the 

 fossilised bones extracted, cleaned, and put together. Some 

 of these are found to be almost identical with those of 

 South Africa ; others, quite distinct, though allied. Fig. 48 

 represents the skull of a huge carnivorous reptile, which 

 must have been about the same size as the herbivorous 

 Pariasauri (abundantly preserved in the nodules), upon which 

 it doubtless preyed. As the skull is two feet long, and the 

 whole head and body about nine feet, it must have far 

 exceeded in size the largest lion or tiger, and probably that 

 of any carnivorous land mammal that has ever lived. 



In North America these reptiles were also present in 

 considerable abundance. Some, forming the sub-order 

 Theriodontia, were allied to the Pariasauri, and were 

 probably herbivorous ; while the Pariotrichidae were carni- 

 vores, as were also a very distinct family, the Clepsydropidae. 

 Of this latter group one genus, Dimetrodon, is here figured 

 as restored by Sir Ray Lankester (Fig. 49). This is sup- 

 posed to be allied to the living Hatteria of New Zealand. 

 These strange carnivorous reptiles of this early period may 

 have preyed upon numerous herbivores which have not been 

 preserved, as well as upon the primitive insects and land 

 Crustacea, which at this period were probably abundant. 



The remarkable thing is, that some hundreds of species 

 of varied form and size, herbivorous and carnivorous, should 

 have been gradually developed, arrived at maturity, and 

 completely died out, during the comparatively short periods 

 of the Permian and Trias, or the interval between them. 



It is probable, however, that these transition periods 

 really occupied a very great length of time, since all known 

 reptiles seem to have originated during this era, though 



