INTEODUCTIOJSr. xv 



many of these (e. g. Archceohyrax) do not seem to differ in any important 

 particulars from some of the smaller Typotheria, others of the more primitive 

 forms belonging to Ameghino's family, the Accelodidse, may perhaps approach the 

 ancestral forms from which the Hyracoidea originated: 



Although Arsinoitherium is certainly the most extraordinary of the Ungulates 

 found in these beds, nevertheless the remains of the primitive members of the 

 Proboscidea are perhaps of greater scientific interest, because they help to fill, 

 at least to a large extent, one of the most obvious gaps in our knowledge of 

 the extinct Mammalia. Previous to their discovery the earliest Proboscideans 

 known were from the Lower Miocene (Burdigalien) of Europe and Northern 

 Africa, aijd although many earlier deposits rich in mammalian remains were known 

 in various parts of the world, in none of them was any trace of Proboscidea found, 

 so that their appearance in Europe at the beginning of the Miocene period 

 must be the result of their immigration from other regions. The probability that 

 Africa would be found to be the original home of these animals was pointed out 

 by several writers, notably by Osborn, Stehlin, and Tullberg. The first of these * 

 suggested that probably not only the Proboscidea but also the " Hyracoidea, certain 

 Edentates, the Antelopes, the Giraffes, the Hippopotami, the most specialised Ruminants, 

 and among the Rodents the Anomalures, Dormice, and Jerboas, among Monkeys 

 the Baboons," and, as his map suggests, the Sirenia also, originated in this region. 

 Osborn also put forward the theory that a succession of migrations from Africa 

 to Europe occurred, notably at the end of the Eocene, at the beginning of the 

 Miocene, and again in the earliest Pliocene. It was in the early Miocene migration 

 that the Proboscidea passed out of Africa for the first time so far as known. 

 Stehlin f, who also emphasized the importance of Africa as a probable centre of 

 mammalian evolution, expressed much the same views. Tullberg J likewise regarded 

 Africa as a centre of mammalian radiation, and pointed to Ilystrix (or the whole 

 of the Hystricognathi), the Simise (Anthropoidea), and the Proboscidea as having 

 probably migrated thence in the early Miocene. It is therefore very satisfactory 



* " Correlation between Tertiary Mammal Horizons of Europe and America," Ann. N. T. Acad. Sci. 

 vol. xiii. (1900) pp. 1-72. 



t "Ueber die Geschichte des Suiden-Gebisses, Pfc. II.," Abhandl. d. Scbweiz. Pala3ont. Gesellsch. 

 vol. xxvii. (1900) p. 477 et seq. 



+ " Ueber das System der Nngetiere," Nov. Act. E. Soc. Sd. Upsala, [3] vol. xviii. (1899) p. 483. Also 

 for the general question of mammalian distribution, see Lydekker, Geographical History of Mammals 

 (.18913). 



