414 



SCIENCE 



[N. S. Vol. XXXVIl. No. 950 



is subjected to a second chewing at the crea- 

 tures' leisure, after having been softened in 

 the stomach. In the horse the mastication 

 must be hurriedly and efficiently done once 

 for all. 



The coloration of living horses gives rise to 

 the belief that the Arab stock has been de- 

 rived from a dappled bay, while in the do- 

 mestic horses of western Europe, probably 

 sprung from a diiferent ancestral species, the 

 primitive hue is dun, the color of withered 

 grass. The tendency toward either melanism 

 (black), erythrism (redness) or albinism 

 (white) gives rise to the various color modifi- 

 cations. Striping is characteristic of all 

 African wild horses, while those of Asia are 

 more uniform. 



The occasional presence of rudimentary 

 paired horn-like processes upon the frontal 

 bone, while never showing a corneous cover- 

 ing, is of interest. They are not vestigial, as 

 no equine ancestors show them, and while 

 Lydekker does not suggest it, may they not be 

 indications of approaching racial old age? 



Cope's idea that the horse tribe had two in- 

 dependent centers of development from ani- 

 mals of more primitive type, one in the old 

 world and a second in North America, is re- 

 jected for that of Matthew, who assumes that 

 " since the horses are represented by a double 

 evolutionary series, one in Europe, a closer 

 one in North America, their center of dis- 

 persal lay far enough north to spread into 

 Europe on one hand. North America on the 

 other, but that the latter was nearer or more 

 accessible; i. e., their center of dispersal was 

 northeastern Asia or Alaska." 



The wild tarpan or Przevalski's horse, still 

 living on the steppes of Tartary and Mon- 

 golia, is the only true horse other than the do- 

 mestic breeds which has survived. Historical 

 evidences for wild horses in Europe may refer 

 to feral animals, the ancestors of which had 

 escaped from bondage. Prehistoric records, 

 on the other hand, such as the drawings on the 

 walls of caves, show the existence of a small, 

 big-headed horse strongly suggestive of the 

 tarpan. This is the so-called steppe type of 

 Ewart. Two others are also represented by 



bones and teeth in the Pleistocene of England 

 and the continent, one the plateau type of 

 Ewart, a fine-headed, slender-limbed pony, also 

 depicted in paleolithic art; and the forest 

 type, a long, low horse with short, thick can- 

 non bones and broad hoofs. All three of these 

 are probably races of the modern Equus ca- 

 hallus and not separate species. 



The author next discusses the domestic 

 horses of the British Isles and some foreign 

 breeds, and their probable origin, including 

 the American feral horses. The latter are 

 derived from those introduced by the Spanish 

 conquerors and are of Barb stock. 



Among other living equines the Kiang and 

 Onager group come nearest the true horses. 

 They are Asiatic in distribution, while the 

 asses are apparently from the north of Africa. 

 " It has been stated that ' the ass, and with it 

 its name, accompanied the progress of the cul- 

 ture of the vine and olive to the north, not 

 crossing the limits of that culture. In pro- 

 portion as the ure-ox, the bison, and the elk 

 died out, the long-eared foreign beast became 

 domesticated in Gaul, receiving various 

 names, and living in the customs, jokes, prov- 

 erbs, and fables of the people. Germany, how- 

 ever, proved too cold for the animal.' " Asses 

 have become feral in South America. Nearly 

 related to the ass is the true zebra of southern 

 and southwestern Africa, which, together with 

 the now extinct quagga and the bontequagga 

 or Burchell's zebra constitutes the distinctively 

 striped horses of the Ethiopian realm. The 

 curious association of zebras, gnus and per- 

 haps a troop of ostriches to fill up the com- 

 pany, is mentioned, the ostriches apprehending 

 danger through the sense of sight, the others 

 through that of smell. The coloring of zebras, 

 the protective value of which has been so 

 vigorously denied by Colonel Eoosevelt, is 

 summarized by the statement that " whatever 

 may be the real truth with regard to some of 

 the disputed points, it is certain that when a 

 zebra enters covert, it becomes, owing to its 

 coloring, indistinguishable." 



The final chapter summarizes our knowledge 

 of the extinct forerunners of the horse, the 

 records of which have been so well preserved. 



