224 Proceedings of Indiana Academy of Science 



woims did not react to illumination on the mid-ventral surface except 

 on the three anterior and the last segment. 



Some of these conclusions were confirmed by tests made, following 

 the removal of certain anterior segments and certain parts of the 

 nervous system. 



A comparison of the histological structure of the more sensitive 

 with the less sensitive regions, revealed the fact that a rather peculiar 

 type of sense-cell is more abundant in the former than in the latter 

 areas. This indicates that these sense-cells are photoreceptors. 



