THE ANCIENT MAMMALS OF BRITAIN. 325 



in Others they conformed to the more normal type in having 

 but two. In these animals the premolar teeth (two of which 

 are shown on the right side of the figure) were only slightly 

 compressed, but the nearly allied small and delicately-built 

 Xiphod 3ns take their name from the extreme compression and 

 secant form of the teeth in question, in which respect they 

 recall the modern Chevrotains, or Mouse-Deer. Whether the 

 Xiphodons are really British it is not clear, although a skull 

 from the Red Crag, evidently derived from an older structure, 

 has been assigned to them. The large size of the " tear-pit," 

 or lachrymal fossa in front of the eye, has suggested for another 

 member of this group, having teeth of the Anoplothere type, 

 the name of Dacrytheriiun, the English representative of the 

 genus having been originally described from the Hordwell and 

 Headon beds under the name of Dichobuiie. 



This completes our list of the Even-toed Ungulates, and we 

 proceed to notice the few early Tertiary British representatives 

 of the Odd-toed group, or those in which the toe corresponding 

 to the human middle finger is symmetrical in itself and larger 

 than either of the others. To this group belong the well-known 

 Palaeolheres {Palceotheriuni)^ so abundant in the gypsum of the 

 Paris basin, and more sparingly represented in the Headon and 

 Bembridge beds of Hampshire and the Isle of Wight. The 

 structure of the cheek-teeth of a medium-sized representative 

 of this genus is exhibited in figure B of the illustration ; and 

 in general form these animals somewhat resembled Tapirs, al- 

 though the neck was relatively longer, and there were but three 

 toes to each foot. It was long considered that the Palseotheres 

 were on the ancestral line of the Horse, but this view is now 

 discarded, and tliey are considered, like the Anoplotheres, to 

 represent an inadaptive type. A much smaller animal, de- 

 scribed as Anchilophus^ of which teeth have been found in the 

 Bembridge limestone, is, however, either very close to, or ac- 



