626 NATURAL HISTORY. 



ences. There is, however, another side. Horses which escape from 

 domestication and run wild change in their appearance, and we have 

 reason to believe that in many respects they revert to their primal con- 

 dition. Marked features of these are that they have a dark stripe extend- 

 ing along the back, two or three stripes across the shoulders, and trans- 

 verse bars on the legs, — facts that would indicate that our horse descended 

 from some form more like the zebra or quagga than the wild horse men- 

 tioned above. 



Passing by the asses (descendants from the wild species south and east 

 of the Mediterranean) and their hybrid with the common horse, — the mule, 

 — we come to the striped horses of Africa, known as zebras and quaggas. 

 Of these there are three species, all beautiful animals with their striped 

 coats. The quagga is the least beautiful of the three, the stripes not 

 extending to the hind quarters or the legs. They live in immense herds, 

 and have a barking neigh, almost exactly reproduced in their name. The 

 zebra is striped all over, and is one of the most beautiful animals in 

 nature, but it is too familiar to need extended description or illustration : 

 specimens occur in every menagerie. The quaggas live in the low lands 

 and plains, while the zebra inhabits the mountainous regions. They 

 always post a sentinel whose sharp neigh sounds a warning when danger 

 approaches, and at such times the whole flock after a moment's gaze dart 

 off from their pastures into regions where they are safe from pursuit. It 

 is frequently said that zebras. and quaggas, are untamable, but this is not 

 correct. Still, it is a labor of some difficulty to break them to harness, and 

 even when this is done the team lacks the reliability and steadiness of 

 the old family horse. 



In the even-toed ungulates we may have either four or two toes, and 

 from what has already been seen those with the larger number must be 

 regarded as the more primitive type ; but whether there be two or four, 

 there is one feature to be noticed, — the foot is divided into two symmet- 

 rical halves, or. to use the Levitical expression, they cleave the hoof. The 

 same law introduces us to another feature in these animals which may also 

 lie noticed here, especially since it serves to divide these forms into two 

 minor groups. In the sumptuary laws just referred to it was not sufficient 

 that the hoof be cloven, in order to render the flesh of the animal 'clean' ; 

 there was further necessary a chewing of the cud. In the pigs and hippo- 

 potamuses this does not take place, but in all the rest there is a rumination. 



In these latter the stomach, instead of being a simple glandular sac, is 

 divided into four portions, each with its special name and function. A 

 cow, for instance, eats for a while, scarcely chewing the grass as it is taken 



