228 



THE WORLD OF LIFE 



CHAP. 



line of descent. But less than ten years ago a number of 

 fossils were obtained by Dr. C. W. Andrews from the 

 Middle and Higher Eocene beds of the Fayoum district of 

 Egypt, which give the long-hoped-for missing link connecting 

 the elephants with other ungulates. 



The most primitive form now discovered was about the 

 size of a very large dog, and its skull does not differ very 

 strikingly from those of other primitive ungulates. It has, 

 however, some slight peculiarities which show a connection 

 with the Proboscidea. These are that the nasal opening is 

 near the end of the snout, indicating, probably, the rudiment 

 of a proboscis ; the back of the skull is also thickened and 

 contains small air-chambers, the first step towards the very 

 large air-chambers of the elephant's skull, whose purpose is 



to afford sufficient 

 surface for the 

 powerful muscles 

 which support the 

 weight of the tusks 

 and trunk. The 

 teeth showtwo short 

 tusks in front in the 

 upper jaw in the 

 same position as the 

 tusks of elephants, 

 while the lower jaw 

 or chin is lengthened 

 out and has two 

 incisor teeth projecting forward. The molar teeth show the 

 beginning of the special characters which distinguish the 

 huge grinding teeth of the elephants. This creature was 

 named MceritJicrium lyonsi ; and its remains have been found 

 in great abundance along with those of both land and sea 

 animals, showing that they were deposited in what was 

 then the estuary of the Nile, though now far inland. 



Somewhat later, in the Upper Eocene, another group of 

 animals, the Palaeomastodons, have been found, showing a 

 considerable advance (see Diagram, Fig. 82). They vary in 

 size from a little larger than the preceding to that of a small 

 elephant. The skull is very much modified in the direction 



Fig. 81. — Skull of Mceritherium lyonsi. 



From the Middle Eocene of the Fayoum, Egypt 



One-seventh nat. size. (B.M. Guide.) 



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