EVOLUTION OF THE HORSE AND THE ELEPHANT 425 



equestrian statues. The profile of the face is distinctly 

 concave, and the short skull is broad between the eyes. 

 The tail vertebras are reduced, and there are only five 

 instead of six lumbar vertebrae. The English thorough- 

 bred horse, remarkable for its speed, owes much of its 

 quality to Arab blood. 



EVOLUTION OF THE ELEPHANT 



I. The evolutionary history of the elephant was long Discovery of 

 unknown, but in comparatively recent years the Fayum ance ^ to * s . of 

 desert of Egypt has yielded a series of fossil animals Egypt 

 which serve to connect the highly specialized elephant 

 of today with much more primitive types. Dr. C. W. 

 Andrews of the British Museum, who obtained most of 

 these fossils, has given a full discussion of the subject. 

 The oldest known member of the series is called Mceri- 

 therium, after the ancient Lake Mceris, near which it was 

 discovered. It was more or less tapirlike, very small in 

 comparison with the elephants, with extremely short 

 tusks. Its relationships with still earlier forms" cannot 

 be made out, but there are certain resemblances to the 

 living manatee in the details of structure, though not at 

 all in appearance. After a time this type gave place to 

 the Palceomastodon (old mastodon), a larger animal with 

 longer tusks, and the lower jaw extended outward, ap- 

 parently for digging. Next we have the Trilophodon, 

 still larger, with long, slightly curved tusks, and enor- 

 mously lengthened lower mandible, which must have 

 served as a regular plow. This type of animal was so 

 successful that it spread far and wide, and even invaded 

 North America. The arrival of the Proboscidea, or 

 elephant group, in America took place in the Miocene, 

 and marks an important date in the geological series. 



