444 ZOOLOGY. 



Eussian, Polisli, Litliuanian, and Swedish horses descend from the *ame 

 stock, to which also belongs the Siberian horse {pi. 109, fig. 11), which 

 during winter is covered with very thick and long hair. 



3. The West European horse is large, less enduring, however, than either 

 of the preceding ones ; here belongs also the Spanish horse, the Sicilian, 

 the French, English, Hungarian, Transylvanian, German, and Italian. 

 PL 110, fig. 5, represents the Norman team liorse^ supposed to be of Danish 

 breed. It is raised in lower ISTormandy. 



The ass, Equus asinus {pi. 110, fig. 2), is another species of the same 

 genus, originally from the great desert of central Asia, and still to be found 

 there in a wild state, in innumerable troops, ranging from north to south, 

 according to the season. The ass has been domestitated like the horse, 

 and renders very great service to man, whom it has followed through, 

 almost all his migrations. A cross breed between the ass and the mare is 

 called a mule, well known to the ancients, who called it Mulus^ or the- 

 mule proper {j^l. 110, fig. 3), produced by the male ass and female horse; 

 whilst they termed Hinnus the mule arising from the union of the male 

 horse with the female ass. Mules are very valuable animals, and capable 

 of being employed where the horse and ass would be useless. The mule 

 stock cannot perpetuate itself, for it soon degenerates when it is not sterile. 

 At any rate, sterility declares itself after the second or third generation. 

 To keep the stock perfect, the parent of both species, the horse and the ass, 

 must always breed together. 



The zebra, Equus zebra {pA. 110, fig. 1), originally from the south of 

 Africa, has never been domesticated, and seldom tam'ed by man. It is 

 nearly of the same form as the ass, but regularly marked with black and 

 white transverse stripes. A female zebra has succe?sively produced an 

 ofispring with the horse and the ass. 



The dzigguetai {Equus hemionus), intermediate by its proportions between 

 the horse and the ass, lives in troops in the sandy deserts of central Asia. 

 It is of an Isabella or light bay color, with a black mane and a dorsal line 

 of the same color. Supposed to be the wild mule of the ancients. 



The couagga and th'e onagga or dawn are two other wild species of 

 horses. 



If the American continent has no indigenous horse in tlie present fiuna, 

 the remains of several species are found in the tertiary deposits of North 

 and another in South America. A few fossil species have been discovered 

 in Europe and in the Sivalic Mountains in Asia. Two extinct genera of 

 this family are already known. 



The genus Hippotherium differs from Equus b}' the structure of the 

 molars, the lamime of which are much more complicated, forming nume- 

 rous zigzag folds. It forms also a transition towards the j^achj-derms 

 proper, inasmuch as the anterior feet possess the rudiments of a fourth 

 finger or toe. Several species have been described as belonging to Europe, 

 but more recent observations seem to reduce their number to one, Avhich 

 lived in numerous individuals in the centre and south of Europe during 

 the meiocene period up to the diluvium. 

 C48 



