6 



layer is not separated from the middle layer by a thin elastic 

 limitary membrane, called Bowman's membrane. 



Fig. 1. 



Diagramatic Section of the Horse's Eye (after D'Arboval) showing 

 the relative position of the various parts. In reading the description 

 of the anatomy of the eye frequent reference should be made to this 

 cut. 



a, Optic nerve ; b, Sclerotic ; c, Choroid ; (J, Retina ; e, Cornea ; /, Iris ; 

 g, h, Ciliary circle, (or ligament) and processes given off by the choroid 

 though represented as isolated from it, in order to indicate their 

 limits more clearly ; i, insertion of the ciliary processes on the crys- 

 talline lens ; ;, Crystalline lens ; k, Crystalline capsule ; I, Vitreous 

 body ; to, n, Anterior and posterior chambers ; o. Theoretical indica- 

 tion of the membrane of the equeous humour ; p, p, Tarsi ; g, g, Fib- 

 rous membrane of the eyelids ; r. Elevator muscle of the upper eyelid ; 

 s, s, Orbicularis muscle of the eyelids ; t, t, Skin of the eyelids ; u, Con- 

 junctiva ; V, Epidermic layer of this membrane covering the Cornea ; 

 X, Posterior rectus muscle ; y, Superior rectus muscle ; z, Inferior rec- 

 tus muscle ; to, Fibrous sheath of the orbit (or orbital membrane) ; 1, 

 Section of orbital arch ; 2, Lachrymal gland ; 3, Section of samal 

 oblique muscle. 



The middle layer is the principal and the thickest part 

 of the cornea; it is fibrous, tough, unyielding and continu- 

 ous, with the sclerotic; its external surface, in most animals 

 is covered with Bowman's elastic limitary membrane and its 



