ORDER UNGULATA. 1 337 



half-cylinder. Moreover, in all existing members of this group 

 the lateral metapodials are either incomplete or totally wanting 

 (fig. 1 2 1 1 ) ; the stomach is composed of four complete cavities ; 

 and the placenta develops structures known as cotyledons. On the 

 skull either horns or antlers are very generally present, at least in 

 the males of recent forms. 



In the Cervidce upper canines are generally present, although 

 with a few exceptions they are of comparatively small size ; the 

 cheek-teeth, and more especially in the earlier forms, are very 

 generally of a more or less brachydont structure, the first true 

 molar being invariably of this type ; and the upper premolars 

 always have both an inner and an outer column, and are 

 never simply secant like those of the existing Tragididce. In 

 the skull there is always a large vacuity in front of the lachry- 

 mal, which prevents that bone from articulating with the nasal. 

 In a large number of forms antlers are present in the male, 

 and in Rangifer also in the female. Antlers, it may be ob- 

 served, are outgrowths of true bone arising from the frontal 



Fig. 1212. — Reduced left lateral aspect of the skull of the Roebuck (Capreolus capred). 



region of the skull (fig. 12 12), which during their development 

 are invested with a vascular, hairy skin. On the completion of 

 their growth a constriction of the blood-vessels near their base is 

 usually brought about by the formation of a burr, and above 

 this point the skin peels off and leaves the bone bare and in- 

 sensible; after a time the antler is shed, leaving a more or less 

 elongated pedicle attached to the skull, from which a new antler 

 is developed. In young animals the antlers are simple, and in 

 those species in which they finally attain a great complexity, this 

 is acquired gradually in successive annual growths. Each antler 

 always consists of a main stem or beam, and usually of one or more 

 branches or tines ; of which the one immediately above the burr 



