_HYRACOIDEA._ The skull of _Procavia_ resembles that of Perissodactyles more than that of any other Ungulates, but differs strongly in the comparatively small size of its facial portion. The posterior portion of the cranium is rather high, the occipital plane being nearly vertical. There is a small interparietal. The nasals are wide behind, and the zygomatic arch is strongly developed, its most anterior part being formed by the maxillae. The jugal and parietal give rise to postorbital processes which sometimes meet, but as a rule the orbit is confluent with the temporal fossa; it is very uncommon for the parietal to give rise to a postorbital process, and even in _Procavia_ the frontal often forms part of the process. The alisphenoid canal, and postglenoid and paroccipital processes are well developed. The tympanic bulla is large and the periotic and tympanic are fused together, but not as a rule to the squamosal. The ascending portion of the mandible is very high and broad, the angle rounded and the coronoid process moderate in size. The hyoid is singular, there is a large flat basi-hyal prolonged laterally into two broad flattened thyro-hyals. Articulating with its anterior end are two large triangular cerato-hyals, which are drawn out into two processes meeting in the middle line. _AMBLYPODA._ In the Uintatheriidae (Dinocerata) the skull has a very remarkable character, being long and narrow and drawn out into three pairs of rounded protuberances, a small pair on the nasals, a larger pair on the maxillae in front of the orbits, and the largest pair on the parietals. The cranial cavity, and especially the cerebral fossa, is extraordinarily small. The orbit is not divided behind from the temporal fossa. The mandible has a prominent angle, and a long curved coronoid process; its symphysial portion bears a curious flattened outgrowth to protect the great upper canines. In _Coryphodon_ the skull is of a more normal character, being without the conspicuous protuberances. The cranial cavity though very small is not so small as in _Uintatherium_. [Illustration FIG. 96. SKULL OF A YOUNG INDIAN ELEPHANT (_Elephas indicus_), SEEN FROM THE RIGHT SIDE, THE ROOTS OF THE TEETH HAVE BEEN EXPOSED. × 1/8. (Camb. Mus.) 1. exoccipital. 2. parietal. 3. frontal. 4. squamosal. 5. jugal. 6. premaxillae. 7. maxillae. 9. supra-occipital. 13. basi-occipital. 14. postorbital process of the frontal. 15. lachrymal. 16. pterygoid process of the alisphenoid. _i_ 1. incisor. _mm_ 3., _mm_ 4. third and fourth milk molars. _m_ 1. first molar.]