32 



and now-a-days, when any incautious opponent ventures to ask^ 

 " Where are the missing links ? " the geological Horse is at once 

 trotted out for inspection. 



The Lecturer then exhibited on the screen, and described some 

 of the earlier forms of the Hoofed Animals ; after which he went 

 on to say : — 



All our representations have been of animals belonging to the 

 same great Order as the Horse ; but we have noticed a considerable 

 amount of variation in the number of toes on each foot. The horse 

 has one, the Ox two, the Hipparion had three, but probably was 

 supported wholly by the middle one, the Rhinoceros had and still 

 has three, the Hippopotamus four, while the Deer, Giraffe, Pig, &c. 

 walk upon two. The number forms the most evident characteristic 

 to the ordinary observer. But the student detects something 

 beyond this. He finds that the hoofed animals fall easily and 

 naturally into two smaller groups, according as the weight of the 

 body is supported on one or on two specially enlarged toes ; these 

 are (a) The Odd-toed (Perissodactyla), (b) The Even-toed 

 (Artiodactyla), the type of the former being the Horse, of the 

 latter, the Ox or Deer. The Palasontologist finds that this division 

 holds good for all their past history, and it is evidently a natural 

 division The typical number of digits among the Mammalia 

 would appear to be five, but this number at the present time is 

 found only on those animals which use their limbs for purposes 

 other than support or locomotion ; e.g., the Mole and the Monkey. 

 In early Tertiary times the number five was much more prevalent 

 than it is now, and was as I said, probably normal. Among the 

 Lngulates the number apparently decreased gradually by disuse as 

 the necessity for them decreased. In those whose favourite habitat 

 lies among soft or marshy ground, the decrease has gone on to a 

 less extent because the spreading out of the toes and a large surface 

 to the foot would be of advantage in giving them a surer footing. 

 " The toes " (of the Hippopotamus) says Sir S. Baker "spread 

 widely upon soft ground, and although not actually web-footed, 

 the skin between each toe expands to a certain degree, which 

 assists the animal's progress when swimming by offering a consider- 

 able resistance to the water." 



As the old surface land became better drained and drier, it was 

 most advantageous to animals living upon such ground that the 

 surface of the foot should lessen, and with it the number of digits, 

 conferring on them thereby a higher rate of speed, a better chance 

 of escape from their enemies. The group containing the Horse, 

 which includes Ass, Zebra, and Quagga, has altered most of all, and 

 there we find the highest rate of speed, the bones of the limbs 

 having decreased and become more compact, and the whole body 

 lighter. And as already said, this classification by the number of 



