274 NEW YORK STATE MUSEUM 



to locate them. Dr Leidy^ and Dr Sochaczewer,^ believed that the 



olfactory organs are situated in the pedal sinus. 



The latter author made the following experiment: 



Having cut off the tentacles of H e 1 i x p o m a t i a^ the wound 

 was allowed to heal. The snails were then placed on a flat plate, 

 the edge of which was smeared with turpentine; both the muti- 

 lated and unmutilated specimens turned away from the edges; 

 this shows that the tentaculae are not the seat of the olfactory 

 organs. 



I do not think that this experiment is at all conclusive, or in 

 fact has any bearing on the matter, as the foot both of Helix 

 and of L i m a X is so extremely sensitive that on the first contact 

 with any substance smeared with turpentine the animal would 

 turn quickly away; the effect being essentially the same as if the 

 animal had come in contact with heated metal. The fatal defect 

 of this experiment is that the sensitiveness of the foot was not 

 taken into consideration. I have tried the same experiment as 

 far as isurrounding the animals with turpentine, but they never 

 turned away till they came in contact with the turpentine. If 

 they turned away on account of the smell, they would do so before 

 touching the turpentine. 



If one observes a snail^ when in motion, it will be seen that the 

 superior tentacles are usually held, essentially, in one position, 

 occasionally striking an object, apparently not seeing it; but the 

 inferior tentacles are constantly in motion, and are bent down 

 toward the object on which the animal is moving, but not touch- 

 ing it. Taking into consideration the limited power of sight, it 

 seems to me that the snail must be assisted by the sense of smell. 



That these tentacles have an important function to serve is evi- 

 dent from their anatomic character. A large nerve proceeds from 

 the principal of the cerebral or supra-esophageal ganglia, which 

 connects at the extremity of the tentacle with a very conspicuousi 

 ganglionic swelling (pi. 13, fig. 4, 5), which gives off numerous 

 nerve fibers to the extremity of the tentacle. That the tentacles 

 are not tactile organs is evident from two facts; first, they would 



^Terrestrial moll, and shells of the United States. 

 2Zeitschrift fiir Wiss. zoologie. 35:133. 



