THE ONE BIG DIGIT OF THE HORSE 269 



With due deference to Dr. Wallace's great authority on these 

 matters, I would ask why does he say ' That horns have not un- 

 frequently arisen from such apparently uncaused variations'? 

 They may be inherited reversionally from some ancestral form. 

 Moreover, why does he think that the Deer and the Antelopes ' must 

 have originated independently ' ? Everything we know about 

 these animals tends to the conviction that they did not originate 

 independently. The horns of the Antelope have a core covered 

 with hard epidermis ; while the horns of the Deer have a core 

 covered with velvety epidermis which is shed : the Giraffe retaining 

 a covering of skin on its horns throughout. In the Deer the 

 epidermis peels off and leaves the core nude. In the Antelope the 

 epidermis hardens into horn, and sheaths the horn permanently, 

 so that the antler of the Deer may be the homologue of the core 

 of the Antelope's horn. 



The remarkable part seems to be the shedding of the Deer 

 horns. We have, however, an analogous phenomenon in the 

 shedding of plant leaves, in the shedding of oak branches {Quercus 

 Robur), in the shedding of the arms of star-fishes. 



Then taking into consideration the digestive characters of both 

 groups, the characters of their limbs, and the absence of incisors 

 from the upper jaw of both, it seems difficult to escape from the 

 conclusion that Antelopes and Deer are closely allied, and have 

 originated from a common stock. 



A number of common characters in the Horse, normal and 

 abnormal, such as the ' Horned Horse from Texas,' ^ would indicate 

 that it also is a branch of the same common stock from which Ante- 

 lopes and Deer arose. 



(/) Then the callosities on the Horse's legs are features which 

 the South American Camel-like ruminants, as I have shown else- 



' American- Journal of Science, 3rd series, vol. 43, 1892, p. 344. 



