276 NEW YORK STATE MUSEUM 



parent vesicles, situated beneath the sheath of the supra-esopha- 

 geal ganglia, one on each side, placed immediately on the gang- 

 lia and connected with nerves proceeding from the cerebral 

 ganglia. They are extremely minute, and are filled with a trans- 

 parent fluid, containing a number of small bodies, composed of 

 concentric layers of carbonate of lime, frequently hollow at the 

 center, called otoliths. During life, and for a short time subse- 

 quent, these bodies have a peculiar vibratory motion. 



The size and situation of these bodies, and their nerves, would 

 naturally lead to the conclusion that as auditory organs they 

 would be of little, if any, use. As with Anodonta, I have 

 tried numerous experiments to tesit the sense of hearing. Any 

 noise which does not jar the animal, has no effect on it. And 

 I have no hesitation in saying that the sense of hearing, if ever 

 possessed, has been lost. 



These remarks apply both to Polygyra and to L i m a x. 



Sense of direction. Snails in common with most animals, with 

 the exception of man, have what has been called t he sixth sense: . 

 that of dire£tion_or^ locality. I had for several months a large 

 box, containing about one hundred snails, in one corner of my 

 library. At the time I was making sections of shells to illustrate 

 this work. I one day examined the snails in the box, and picked 

 but three which were to all appearances dead. These I took out 

 for the purpose of making sections of the shell. Not having time 

 then, I laid them on the window ledge, in the opposite corner o'f 

 the room, about 12 feet from the box. Several hours later I 

 looked for them, and, not finding them, thought they had been 

 accidentally brushed from the ledge. Looking on the floor for 

 them, I noticed the peculiar, glass-like trail made by a snail while 

 moving. Then, examining carefully the spot where I had laid 

 them, I found that, though apparently dead, they were alive, and 

 I easily traced the three snails by their trails, which led in an 

 absolutely straight direction to the box in which they had been 

 kept, and I found them under the edge of the mosquito netting, 

 which had been tied over the box, as near to the interior of the 

 box as it was possible for them to reach. Afterward I experi- 



