The horse, its treatment in health and disease with a complete guide to breeding, training and management . of whicha side view is given at «, fig. 668, whilst the teeth of the Protohipjjusand Hipparion show an ad^?ance towardsthe state of hypsodont or high-crownedteeth (6, fig. 668) which culminates inthe horse (c, in the same figure). Next in chronological order to thePhenacodus mention must be made of theHyracotherium and the Eohippus, alsofrom the Eocene, which are, so far as isat present known, the earliest direct an-cestors of the horse, the former in the Old,the latter in the New AVorld
The horse, its treatment in health and disease with a complete guide to breeding, training and management . of whicha side view is given at «, fig. 668, whilst the teeth of the Protohipjjusand Hipparion show an ad^?ance towardsthe state of hypsodont or high-crownedteeth (6, fig. 668) which culminates inthe horse (c, in the same figure). Next in chronological order to thePhenacodus mention must be made of theHyracotherium and the Eohippus, alsofrom the Eocene, which are, so far as isat present known, the earliest direct an-cestors of the horse, the former in the Old,the latter in the New AVorld. They may,indeed, be varieties of the same animal,and they are described as being aboutthe size of a fox. In the fore-feet therewere four well-developed toes and therudiment of another, the hind-feet hadthree toes, as represented in the Pro-torohippus (fig. 2, Plate LXXI), whichmarks the next step in the order of de-velopment. The change which has takenplace in the latter animal, as will be seen by reference to the figure,consists only in the loss of the rudiment of the first digit, leaving second,. Fig. 668.—Short- and Long-crownedMolar Teeth a, Anchitherium; h, Hipparion; c. Horse. 512 THE HOUSES POSITION IN THE ANIMAL WORLD third, fourtli, and titth digits. It will })e observed that the third ormiddle digit is the largest of the four, representing in feet what haspreviously been termed the one big digit of the horse. The Protorohippus has a well-developed ulna, a well-developed til)ula,and short-crowned grinders of simple pattern. Comparing its skeleton (Plate LXX) with that of the horse, we seethat there is a general correspondence in grace and delicacy of outline inthe two animals. The next drawings (fig. 3, Plate LXXI) represent the fore- andhind-feet of the Mesohippus, from the Lower Miocene immediately suc-ceeding the Eocene in which the Protorohippus was found. In comparingthis set of figures witli those last described, it \vi\\ be seen that only threeprominent dig
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecthorses, bookyear1906
