A. LIAUTARD. 
255 
the frontal. It presents several openings for the passage of blood 
vessels and nerves ; is surrounded by a somewhat thick layer of 
adipous tissue, whicli separates it from the surrounding muscles 
and from the coronoid process of the maxillary, which might 
pinch it during the motion of the jaws. In its interior are found 
the globe of the eye with its muscles, the blood vessels and 
nerves of the eye. 
Differences .—In ruminants , the anterior opening of the orbital 
cavity is formed by the frontal, larymal and zygomatic bones. The 
process of the temporal does not extend as far as the orbit. This 
opening is notched on the internal side, where the frontal and lary¬ 
mal unite ; the supra-inferior diameter is more developed than the 
transversal; the orbital foramen, more developed, is situated more 
backwards and inwards ; simple at its internal orifice, it divides and 
opens on the anterior face of the frontal by one, two, or three orifices. 
In dog, and generally in carnivora, the orbital process of the 
frontal does not unite with the zygomatic arch. In its place is a 
strong ligament upon which the antero superior border of the 
ocular sheath is attached. 
The orbit of the pig is like that of carnivora. 
MUSCLES OF THE EYE. 
They are situated in very deep position. I am not aware that 
operations of myotomy, so common in human surgery, were ever 
performed upon animals, as in case of strabismus, affections which 
are very rare in large domestic animals. Few cases are recorded. I 
have seen one in the dog, and Mr. H. Bouly has observed one in 
the horse. 
The muscles of the eye form two layers round the optic nerve; 
the most external is constituted by the straight muscles, divided 
into superior, inferior, external, and internal, and having common 
characters. They are little fleshy bands, thin on the borders, by 
which they are all more or less united. The separated contraction of 
each of these muscles carries the ocular opening on the side of the 
muscle in action, either above or below, outward or inward, and 
even in intermediate positions if they contract two by two. 
Inside of this first layer, one finds another, formed like the 
first of four fasciculi, united by their borders; the mass of 
