EYE OF THE ENGLISH SPARROW 



375 



The superior orbital artery (OS A) runs up over the eyeball, 

 partly encu'cling it, and finally leaves the orbit at the upper 

 anterior portion. In its course it gives off a number of branches 

 to the eye. Close to its origin from the external ophthalmic it 

 gives off a small branch to the lacrimal gland. Another branch, 

 the inferior palpebral artery (PI), goes to the lower lid. This 

 supplies the main portion of the lower lid and forms a portion of 



OpT 



Fig. 13. Front view of the eye of the sparrow, the external layer of the lids 

 being removed to show the arrangement of the arteries and veins, c, anterior 

 ciliary arteries; EF, external facial vein; EO, external ophthalmic artery; Lg 

 lacrimal gland; 0/yl, infra-orbital artery; OSV, supra-orbital vein; P, inferior 

 palpebral artery and vein; PS, superior palpebral artery and vein. X 10. 



a ring of blood-vessels which surround the interpalpebral space 

 close to the margins of the lids. It also sends off a branch, the 

 superior palpebral artery (PS), to the upper lid. It is united to 

 the inferior palpebral by the small marginal artery which encir- 

 cles the palpebral space. It forms also a few ciliary arteries. 

 In its course over the eye the superior orbital gives off a number 



