114 ELEMENTARY BIOLOGY. [CHAP. 



S. The i,th cranial nerve (n. patheticus) ; seen, on 

 slightly pulling the eye-ball outwards, skirting 

 the inner wall of the orbit to reach the su- 

 perior oblique muscle. 



€. The T,rd cranial nerve (oculomotor). A branch 

 of this may be seen breaking up in the 

 superior rectus muscle, if that be cut across 

 near its point of attachment to the eye-ball 

 and turned back. 



£. The lower eyelid ; follow it forwards, it will be 

 found to be continuous with a strong tendon 

 which passes through a loop immediately ex- 

 ternal to the superior oblique muscle. 



b. Ventral aspect. Turn the head over and pin 

 down ventral surface uppermost; remove the 

 entire lower jaw and floor of the mouth, and 

 dissect off the mucous membrane of i:s roof 

 with care, 

 u. The levator bulbi muscle ; a sheet-like mass 

 underlying (overlying as seen) the whole eye- 

 ball; its fibres pass obliquely outwards and 

 backwards. 



Compare a transverse section such as is de- 

 scribed at Sect. C. 3. The fibres will be found 

 to pass between the upper jaw and the in- 

 ternal dorsal wall of the orbit. 



p. The inferior oblique ; a small muscle passing 

 upwards and inwards between the antero- 

 internal face of the eye-ball and the orbit. 



7. The JIarderian gland ; a nodular mass im- 

 mediately behind /?, interposed between the 

 eye-ball and orbit. 



