87 



Beer has described the mechanism of accomodation and has shown that it is 

 much the same as in the eyes of Teleosts, although there are important differences. 

 In both cases the eye is myopic , the convexity of the lens is unchangeable , 

 and accomodation is effected by drawing the lens toward the retina. In fish the 

 falciform process , or musculus retractor lentis , draws the lens toward the retina , 

 but in the Cephalopod eye , the ciliary muscle accomplishes this. The outer sur- 

 face of the eye is convex and the contraction of the ciliary muscle flattens the 

 outer wall of the eye and draws the lens toward the retina. Moreover, the 

 more violent contraction of one segment of the ciliary muscle turns the lens so 

 that a ray , which otherwise would not reach the retina , strikes it. Thus , by 

 turning the lens , a moving body may be watched without turning the eye or 

 the head. 



