THE HORSE. 29V 



rior face of the centrum of tlie last lumbar is still distinctly 

 convex. Tlie spines of these vertebrae increase in length to 

 the fourth or fifth. The spine of the sixteenth is vertical, /«?-<-^ 

 those in front incliniDg backward, and those behind a little 

 forward. 



In none of these vertebriie do the prezygapophyses bend 

 round the postzygapophyses of the vertebra in front, as is 

 often the case in the Artiodactyla. The transverse processes 

 of the penultimate, and of the last, lumbar vertebrae present^ ,^,^,^ 

 concave facets upon their posterior margins, which articulates, — 6-^^. 

 with convex facets developed upon the anterior margins of a.^^ . 

 the last lumbar and first sacral vertebrre respectively. 



In the skull, the plane of the supra-occipital is inclined 

 upward and forward, and gives rise to the middle part of a 

 transverse ridge which is continued at the sides into the scjua- 

 mosal. The ridges which limit the origins of the temporal 

 muscles above, unite in the middle line posteriori}'-, and thus 

 produce a low sagittal crest. The orbit is bounded behind by 

 the united post-orbital processes of the frontal and the jugal. 

 The lachr^Tiial aperture lies in the orbit. The nasal bones 

 unite, for a short distance only, with the premaxilla. There 

 is no praenasal bone. The posterior margin of the palate is 

 opposite the penultimate molar tooth. The glenoidal surface 

 is transversely elongated and convex from before backward. 



The tympanic bulla is not very large, and is rugose inferi- 

 orly. It is not anchylosed wdth the surrounding bones. The 

 post-tympanic process of the squamosal does not approach 

 the post-glenoidal process of the same bone, below^ the meatus 

 auditorius. 



The proper mastoid process is distinct, but short. There 

 is a long and strong paramastoid developed from the ex-oc- 

 cipital. 



The rami of the mandible are anchylosed at the symphysis. 

 The perpendicular part of each ramus is long, the condyle 

 transverse and convex from before backward, and the narrow 

 coronoid process rises far above the level of the condyle. In 

 a longitudinal section of the skull the cerebral chamber lies 

 almost altogether in front of that for the cerebellum. 



The structure of the limbs of the Horse is such as might 

 be expected from its preeminent cursorial powers. 



That excessive development of the epidermis which gives 

 rise to a nail takes place, in the Horse, not only upon the 

 dorsal surface of the terminal joint of the digit, but upon its 

 ventral surface and sides, and thus produces a hoof. 



