VISION IN THE MOUSE 597 



would expect to find cones if anywhere, there was no sign of a 

 cross section of a cone. 



The best presentation of the retina of the mouse can be given 

 by a diagram (fig. 10). Fig 9 is a drawing of a section through 

 the whole eye, showing the size of the lens in comparison with the 

 rest of the eye. 



Fig. 10 A Section from central region of retina of mouse, showing rods with- 

 out admixture of cones. 



B Retina of mouse, showing entrance of optic nerve. 



C First section of retina of eye of mouse, dorsal cutting, showing choroid coat, 

 pigment cells and rods, no cones being present. 



D Section of retina of eye of rabbit, showing rods and cones, a, nuclear layer; 

 b, cones; c, rods; d, pigment. 



THE JOUHSAL OF COMPARATIVE NET KOLOG1 k.ND PSYCHOLOGY, VOL. 20, SO. 6. 



