330 ZOOTOMY. 



from the postero-internal region of the orbit along with the 

 recti (§338) and passing forwards and upwards to the under 

 surface of the anterior end of the supraorbital process : there 

 it passes through a tendinous loop attached to the bone, 

 and then passing downwards and slightly backwards is 

 inserted into the eyeball. 



336. The lacrymal gland, a pinkish mass situated in 

 the upper and posterior region of the eyeball. 



337. The Harderian gland, a white, opaque, lobulated 

 body situated in the anterior region of the eyeball. 



338. The four recti and the inferior oblique have the same 

 relations as in the lower Vertebrata ( p. 77, §§ 192 — 194, and p. 7S, §§ 

 201, 202). 



339. The third, fourth, and sixth cerebral nerves, issuing from the 

 sphenoidal fissure, and having the same general distribution to the eye- 

 muscles as in the lower Vertebrata (pp. 77, 78, §§ 195 — 197, 203). 



340. The retractor bulbi, a conical muscle lying immediately within 

 the recti, and forming a sheath round the optic nerve : it is supplied by 

 the sixth nerve. 



34r. The orbito-nasal nerve, or first division of the iifth, leaving the 

 skull through the sphenoidal fissure and passing along the upper edge of 

 the inner wall of the orbit. 



342. The optic nerve, leaving the skull by the optic foramen, and 

 pa>;sing to the inner and posterior region of the orbit. 



XLI.i Remove both eyes : divide one of them into an 



inner and an outer hemisphere by an equatorial 



incision, i.e. a vertical incision taken at right angles 



to and through the centre of a line joining the pupil 



and the optic nerve : divide the other into an 



anterior and a posterior half by a vertical incision 



at right angles to the first, that is passing through 



the pupil and entrance of the optic nerve. Note : 



343. The fibrous sclerotic, the one-layered choroid, 



' As it is necessary to examine the eye while quite fresh, it will 

 probably be found convenient in practice to substitute an ox's or sheep's 

 eye for the rabbit's. 



