Holmes, Phototaxis in Crabs. 497 



tion are different from those employed in ordinary running. They 

 are special movements employed to check deviations from a cer- 

 tain course, a circumstance which would greatly complicate any 

 attempt to explain orientation as a comparatively direct response. 

 The results of observations on fiddler crabs tend to confirm the 

 conclusion reached in studies made on the phototaxis of Ranatra,' 

 namely, that light is followed much as an animal pursues any other 

 object of interest such as prey, or its mate, and until we can give 

 a physiological explanation of these phenomena we are not, I 

 believe, in a position to give a satisfactory explanation of orienta- 

 tion to the direction of the rays of light. 



iThereactionsofRanatra to light. Jour. Comp. Neur. and Psych. ,yo]. 15, 1905. 



