THE HEAD 55 



and into which powerful muscles are inserted. They are called 

 the coracaid, beak-like, processes or prolongations, F F, of the 

 occipital bone. 



Running forward, and forming outwardly a part of the base, 

 and inwardly a portion of the floor of the skull, is what, from 

 its wedge-like shape, is called the cuneiform process of the 

 occipital bone (fig. i. Fig. 3). It is thick, strong, and solid, and 

 placed at the bottom of the skull, not only to be a proper foun- 

 dation for, and to give additional strength to, the arch on either 

 side, but speedily to stop all vibration and concussion. 



At the base of the skull, and anterior to or below the oc- 

 cipital, lies the sphenoid, wedge-like bone (fig. k. Fig. 3). Its 

 body, likewise called the cuneiform or wedge-shaped process, is 

 a continuation of the same process of the occipital, and, like it, 

 is thick and solid, and for the same important purpose. This - 

 bone branches out into four irregular bodies or plates, two of 

 which are called the leings, and two running to the palate, the 

 legs. They could not be represented in the cut, and there is- 

 nothing important belonging to them, so far as this work is con- 

 cerned. Internally (fig. k), the sphenoid forms a portion of the 

 cavity of -the skull. 



Of the ethmoid, sieve-like, bone, little can be seen outwardly. 

 A small portion is found in the back- part of the orbit, and in 

 the cavity of the cranium ; but the most important part of it is 

 that which is composed of a great number of thin plates, form- 

 ing numerous cavities or cells (fig. I, Fig. 3), lined with the 

 membrane of the nose, and entering into its cavity. The upper 

 portion is called the cribriform or sieve-shaped plate, from its 

 being perforated by a multitude of little holes, through which 

 the nerve connected with smelling, passes and spreads over the 

 nose. 



Altogether these bones form a cavity of an irregular oval 

 shape, but the tentorium penetrating into it, gives it the appear- 

 ance of being divided into two {d. Fig. 3). 



The cavity of the skuU may be said to be arched all round. 

 The builder knows the strength which is coimected with the 

 form of an arch. If properly constructed, it is equal to a solid 

 mass of masonry. The arch of a horse's skuU has not much 

 weight to support, but it is exposed to many injuries from the 

 brutality of those l3y whom he should be protected,and from ac- 

 cidental causes. 



On raising any part of the skull of the horse, the dense and 

 strong membrane which is at once the lining of the cranium and 

 the covering of the brain — ^the dura, mater — ^presents itself. It 

 is united to the membranes below by numerous little cords or 

 prolongations of its substance, conveying blood and oommuni- 



