HISTORY OF THE ARTIODACTYLA 411 



from easy. ''The great difficulty which all zoologists hav^e 

 felt in subdividing them into natural minor groups arises 

 from the fact that the changes in different organs (feet, skull, 

 frontal appendages, teeth, cutaneous glands, etc.) have pro- 

 ceeded with such apparent irregularity and absence of correla- 

 tion that the different modifications of these parts are most 

 variously combined in different members of the group." ^ 

 Two main sections of the suborder are, however, sufficiently 

 well defined, (1) the Cervicornia and (2) the Cavicornia. 



SECTION CERVICORNIA. DEER AND GIRAFFES 



This section includes two families, the giraffes and the deer. 

 Inasmuch as the former have not now and never did have any 

 representatives in the western hemisphere, for the purposes of 

 this book the section becomes identical with the deer family. 



8. Cervidce. Deer 



In most of the deer now existing the male has antlers. The 

 antler is a bony outgrowth from the frontal bone of the skull 

 and is annually shed and replaced, increasing, as a rule, in 

 size and in the number of branches with each renewal. During 

 the period of growth the antler is richly supplied with blood- 

 vessels and covered with skin and is then said to be '4n the 

 velvet," which dries and peels off when growth is complete; 

 after the rutting season a layer of bone at the base of the antler 

 is resorbed, loosening the antler, which is then shed. There 

 is, however, a permanent, cylindrical process, of greater or 

 less length, from each frontal, the ''pedicle,'' from which the 

 antler is annually reproduced, and around the base of the antler 

 and shed with it is a roughened ring, the "burr." Among 

 the different genera of deer there is great variety in the form 

 and size of the antler, from a single spike to the immense and 

 complicated appendages of the Wapiti {Cervus canadensis). 

 As a rule, the ''beam'' or main stem of the antler and its 



1 Flower and Lydekker, op. cit., pp. 307-308. 



