78 



The Ohio Naturalist. 



[Vol. VII, No. 4, 



With orange light at the aperture and fifteen to eighteen 

 shrimps in the field, white light was placed at the opposite end, 

 removing the orange light at the saine time, three shrimps were 

 at the other end (white light) in one minute, and eleven or twelve 

 in five minutes. Changing back again to orange, five shrimps re- 

 turned in one and one-half minutes and fourteen in five minutes. 

 Experiments were continued in this manner for about an hour and 

 a half with practically the same results, however, yellow light 

 with which experiments were closed did not cause a ready 

 response. This was probably due to the fact that the shrimps 

 were suft'ering from fatigue, because yellow light used on fresher 

 individuals had the same effect as any other light. 



Li^kt>^(X 



Fig. 2. Diagram showing course taken by some shrimps from pond- 

 weeds to light shed through aperture A in covered end of aquarium. See 

 text for explanation. 



Later in the season two apertures were used of equal diameter, 

 (about 3-4 by 3-4 inch), side by side, in the same pasteboard 

 cap and about two inches apart. Two different colors were then 

 used at the same time to test whether there was any preference. 

 It W'as found by careful observation that there was no apparent 

 choice, except as stated above, a possible preference for red. 



(Note. — The screen used for colored light was made of the best quality 

 tissue paper from one to three fold depending on the density. This paper 

 was simply placed over the aperture in front of the acetylene gas lantern. 

 The light thus obtained was good for all practical purposes, though great 

 stress should not be placed on details, since the writer was not able to 

 regulate carefully the intensity of the light so as to secure uniform results.) 



Conclusions. — Palaemonetes exilipes Stimpson, is the com- 

 mon shrimp of Sandusky Bay, though not abundant. Shallow 

 water with sandy bottom and rich in vegetation afl'ords the most 



