8 PROCEEDINGS OF THE ACADEMY OF [Jail., 



per cent, of the time, the tip end of the black siphon alone projecting 

 above the sand — 5 mm. — a most inconspicuous object. 



The following table gives the records of the activity of nine individuals 

 for a period of six weeks. It indicates the periods of rest and activity 

 expressed in days. Plate V shows these periods of rest and activity 

 distributed in space. 



Table III. 



Gasteropod. Days active. Days buried. Days quiet. Days of food. 



Sycotypus No. 2 21 16 3 2 



No. 10 2 38 1 



F, carica No. 3 9 25 6 



No. 4 5 34 1 



No. 5 11 14 



No. 6 10 4 26 



F. perversa No. 1 7 29 4 1 



No. 7 10 30 2 



No. 8 7 33 1 



These experiments were carried on in Philadelphia and so w^ere not 

 under perfectly natural conditions. They show how far apart the meal 

 times are. During these experiments F. carica never ate. If these 

 observations reflect at all the normal habits of the individual, they can- 

 not, I think, be a very serious oyster pest. 



Sycotypus and Fulgur do not always react to their food in the same 

 manner, but they react to different Lamellibranchs in a way best 

 suited to getting at the soft parts of the animals. Therefore the 

 behavior is adaptive (Jennings, 1906, 1907). 



Another question is, are these organisms intelligent? Jennings 

 (1906) defines intelligence as a modification of behavior in accordance 

 with experience. The usual way to test this is by habit formation 

 (Jennings, 1907). "(1) The organism must be presented with a 

 problem to be solved. (2) The organism must 'try' to solve the 

 problem in several different ways. (3) It must be able to solve the 

 problem in but one or a few ways." 



In accordance with these criteria I presented the mollusks with a 

 simple maze problem with oysters as "bait." Although without food 

 for a week, they buried themselves in the sand and did not move 

 again. At the end of two weeks I discontinued the experiment. To 

 show the normal behavior of these animals I plotted their movements 

 for a period of six Aveeks. This gave no results except those embodied 

 in the earlier part of this paper. The diagrams show, however, how 

 very sluggish these mollusks are. It is probably impossible by any of 



