128 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



positions have, of course, led to the development of the 

 tumour in the part of the orbit behind them. The 

 internal and external recti are shown in the figure : they 

 are longer than in the normal condition, are attenuated, 

 and flattened out into sheet-like structures. The superior 

 and inferior recti are not represented in the figure, being 



Rectus 

 Interior 



Obliquus 

 InTer/or.: 



hidden by the mass of the tumour. All the eye muscles 

 lie on the surface of the tumour, and do not pass into 

 its substance at any place. 



The optic chiasma is normal, and the right optic 

 nerve bends sharply upwards as it leaves the brain cavity, 

 and runs along the posterior surface of the tumour. It 

 really lies directly underneath the rectus externus, but 



