Hadley, Behavior of the American Lobster. 



267 



or more before it occurred, then at the proper moment the light 

 was admitted and the consequent reaction observed. On the 

 other hand, it was common to find the larvae on their backs and 

 oriented obliquely to the rays of light. When the larva was oriented 

 in this manner and the Hght was admitted, there usually occurred 

 either a forward or a backward rotation (Fig. 14), but the forward 

 rotation was most common. Whichever one occurred, however, 

 the final orientation was the same : the back of the larva was 

 again brought uppermost, and the head was directed away from 

 the source of light. 



Fig. 14. For description, see Case 2. Fig. 15. For description, see Case 4. 



Corollary I — If the larva was oriented with the back below, the 

 head toward the closed window, and the body-axis oblique to the 

 direction of the incident rays, the resulting orientation was a com- 

 bination of the upward and forward rotation and a swing of the 

 body, pivoted on the middle of its long axis, away from the inci- 

 dent rays (this last reaction was similar to Case i. Cor. i, except 

 that in the former instance the larva oriented back below). The 

 final orientation was as in Case 2 (Fig. 14, B'). Whether the inci- 

 dent rays were in plane A, B, or C did not appear to make as 

 much difference in the manner of orientation when the lobster 

 was lying back below. It was observed that rays coming from 

 above (plane A) more frequently determined the backward rota- 



