824 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



recti, and are inserted into the superior posterior surfaces 

 of the eyes. These posterior slips are the rotatory slips of 

 the superior oblique muscles, and their function* is to 

 cause a rotation of the eye on its optical axis, a movement 

 which is very exceptional among fishes as among higher 

 vertebrata, and which is doubtless a special adaptation to 

 the peculiar mode of life of the Pleuronectidse. The 

 extent of the rotation may be as much as one-eighth of a 

 circle. 



Inferior oblique muscles (obi. inf.). — Both right and 

 left muscles originate in the left prefrontal in the same 

 region as that from which the superior muscles take 

 origin. The left muscle passes upwards and backwards 

 along the external wall of the orbit and is inserted into 

 the inferior middle surface of the eye-ball. The right 

 muscle takes origin a little in front of the left, and, as in 

 the case of the superior muscles, the proximal portions 

 cross each other. It then passes through the ethmoidal 

 fenestra with the superior muscle of its side, and passes 

 upwards and backwards along the external wall of the 

 right orbit, and is inserted in a corresponding position to 

 that of the left eye. The inferior are slightly thicker than 

 the superior muscles. 



The superior recti (r. sup.). — These are strong muscle 

 bundles originating in a strong oblique partition crossing 

 the eye muscle canal. They run forwards in the latter, 

 slowly diverging from each other, and emerge on either 

 side of the interorbital septum. They are inserted into 

 the superior and posterior margins of the eye-balls under- 

 neath the rotatory slips of the superior oblique muscles. 



The inferior recti (r. inf.). — Also rather thick muscles 

 which take origin far back in the eye-muscle canal at 

 about the transverse level of the articulation of the head 

 ♦Bishop Harman — Journ. Anat. Phys., vol. xxxv., pp. 1-40, 1899 ; 



