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SCIENCE 



[N. S. Vol. XXX. No. 767 



found in the Permian and Trias of a large 

 part of the world. Remains of them were 

 first met with in India, then in North 

 America, and next in Scotland, while dur- 

 ing the last few years Professor W. Ama- 

 litzky has disinterred so many nearly 

 complete skeletons in the north of Russia 

 that we are likely soon to learn more about 

 them from this European country than 

 from the South African area itself. Quite 

 lately I have received numerous bones 

 from a red marl in Rio Grande do Sul, 

 southern Brazil, which show that not 

 merely Anomodonts, but also other char- 

 acteristic Triassic land reptiles, were like- 

 wise abundant in that region. We are 

 therefore now embarrassed by the richness 

 of the sources whence we may obtain the 

 ancestors of mammals. Whereas some 

 years ago it appeared sufficient to search 

 South Africa for the solution of the prob- 

 lem, we are now uncertain in which direc- 

 tion to turn. We are still perhaps inclined 

 to favor the South African source ; but this 

 is only because we know nothing of the 

 Jurassic land animals of that part of the 

 world, and we cherish a lingering hope 

 that they may eventually prove to have in- 

 cluded the early mammals for which we 

 have so long sought in vain. 



The mystery of the origin of the marine 

 mammals of the order Sirenia and Cetaeea 

 appears to have been diminished by the dis- 

 coveries of the Geological Survey of Egypt, 

 Dr. Andrews and Dr. Fraas in the Eocene 

 and Oligocene deposits of the Mokattam 

 Hills and the Fayum. It is now clear that 

 the Sirenians are closely related to the 

 small primitive ancestors of the elephants; 

 while, so far as the skull and dentition are 

 concerned, we know nearly all the links be- 

 tween the early toothed whales (or Zeuglo- 

 donts) and the primitive ancestors of the 

 Carnivora (or Creodonts). The most 

 primitive form of Sirenian skull hitherto 

 discovered, however, is not from Egypt, but 



from the other side of the world, Jamaica ; 

 and exactly the same Zeuglodonts, even 

 with an associated sea-snake, occur so far 

 away from Egypt as Alabama, U. S. A. 

 The problem of the precise origin of these 

 marine mammals is therefore not so simple 

 as it would have appeared to be had we 

 known only the Egyptian fossils. The 

 progress of discovery, while revealing many 

 most important generalities, has made it 

 impossible to vouch for the accuracy of 

 the details in any ' ' genealogical tree. ' ' 



Another difficulty resulting from the 

 latest systematic researches is suggested by 

 the extinct hoofed mammals of South 

 America. The llamas, deer and peccaries 

 existing in South America at the present 

 time are all immigrants from the northern 

 continent; but during the greater part of 

 the Tertiary period there lived in that 

 country a large number of indigenous 

 hoofed mammals, which originated quite 

 independently of those in other regions. 

 They seem to have begun in early Eocene 

 times much in the same manner as those 

 of the northern hemisphere ; but as they be- 

 came gradually adapted for life on hard 

 ground, they formed groups which are 

 very different from those with which we 

 are familiar in our part of the world. 

 Some of them (Proterotheriidae) were one- 

 toed mimics of the horses, but without the 

 advanced type of brain, the deepened 

 grinding teeth, the mobile neck, or the 

 really effective wrist and ankle. Others 

 (Toxodontidas) made some approach 

 towards rhinoceroses in shape and habit, 

 even with a trace of a horn on the nose. 

 Until their independent origin was demon- 

 strated, these curious animals could not be 

 understood; and it is probable that there 

 are innumerable similar cases of parallel 

 development of groups, by which in our 

 ignorance we are often misled. 



It would be easy to multiply instances, 

 but I think I have now said enough to show 



