OLFACTORY REACTIONS OF MARINE SNAILS 197 
of scenting behavior. Presently the proboscis was extended 
and the anterior end of the foot raised, as if it were attempting 
to climb up to the bag. The lifting of the siphon was also very 
marked. After moving away and returning two or three times, 
it finally succeeded in gaining a foothold on the side of the jar 
directly beneath the bag containing the oyster, and crawled 
upward in a straight line until the siphon tip touched the bag. 
It was then offered a piece of oyster which it speed ly devoured. 
No attention was paid to the unbaited ball of cheese cloth. 
Other experiments were carried on in a larger square wooden 
tank which was about seventy-four centimeters wide and slightly 
over eighteen centimeters deep. Sea water entered through a 
rubber tube suspended near one side of the tank. The end of 
the tube rested on the bottom, and was so arranged that the 
current first swept across a portion of the tank before eddying 
about in various directions. The water overflowed at the top 
of the tank. 
Three snails were placed in the aquarium, and when the test 
was made, all were resting. Then a piece of cheese cloth con- 
taining an oyster removed from its shell, was tied over the end 
of the tube so that the water flowed over the oyster and through 
the cloth. Within a minute and a half, all three animals were 
in motion. Two minutes and a half later two of the snails 
touched the cheese cloth with their siphons. One of them was 
removed, and the third snail arrived at the tube only a minute 
and a half afterward. Thus all the animals located the source 
of the odor in less than six minutes. As they moved actively 
about the aquarium their tentacles curved downward, and their 
siphons swept alternately to the right and left. 
Other snails, which were tested in the same way, showed similar 
responses. After the water had been running for about a half 
hour and the juices of the oyster had been considerably dispersed, 
they exhibited no tendency to move toward the source of the 
current. 
These tests indicate that Busycon finds food not by accident- 
ally coming upon it as a result of random movements, perhaps 
initiated by olfactory stimulation, but, on the contrary that 
