ORYCTOLAGUS 



175 



antero-inferior angle of the orbit. The posterior free projecting 

 extremities of the malars are large. 



The mandible is characterized by the large size of the 

 mental foramina, which are situated nearer to the cheek-teeth 

 than in Lepus. 



The teeth are as in Lepus (see below), but the longitudinal 

 grooves of the large upper incisors are shallow, and never filled 

 with cement. These teeth are more deeply implanted than in 

 Lepus europisus, although less so than in the varying hares ; the 

 course of their roots can only with difficulty be seen externally. 



ext. 



VIl 



t. 



Fig. 34. — Magnified diagrammatic view of transverse section of anterior surface of a large upper 

 incisor of (l) Oryctolagus, and (2) lepus, to show the longitudinal groove and the cement 

 with which it is usually filled in Z^aj. Ant. = anterior ; int. = interior ; ext. = external. 



In the skeleton the cervical vertebrae are uniformly shortened ; 

 the costal processes project comparatively far from their centra, 

 and the anterior and posterior spines are less pronounced. 



The lumbar vertebra; have transverse processes of the 

 same relative length and width as in Lepus, but they do not 

 rise abruptly from the anterior half of their centra ; besides the 

 anterior attachment, each has also a rather long posterior root 

 following nearly the whole of the posterior half of the centrum, 

 and sharply sloping into the process itself. 



There are sixteen to seventeen caudal vertebrae. 



The anterior ribs have the shafts only moderately enlarged 

 ventrally. 



The scapulae are relatively narrow, with their superior 

 borders straighter and less convex, the antero-superior angles 

 relatively pronounced and not so gradually rounded as in Lepus, 

 and the supra-spinous fossae relatively narrow. 



The ulnae are very strong, and lie alongside the radii. The 

 humeri are about equal in length to the forearms. 



