272 NEW YORK STATE MUSEUM 



fore entering the collar, one branch passes through the muscles, 

 the other continuing in the pulmonary chamber. 



From the inferior part of the lateral ganglia proceed five nerves 

 on each side {u), continuing to the integument. 



From the pedal ganglia proceed two large nerves, running nearly 

 directly backward and parallel to the central part of the base of 

 the foot, giving off several branches. From the pedal ganglia 

 there are about 12 other nerves, supplying the base of the foot. 



The ganglia are composed of cells or gloibules, varying very 

 much in size, round or polygonal from mutual pressure, having a 

 nucleus which occupies one half or two thirds the globule. The 

 nucleus has several transparent nuclei. The nerves consist of 

 bundles of tubuli. The walls of the tubuli are transparent. 



Special organs of sense 



Touch. The sense of touch is extremely acute in every part of 

 the foot; the integument and base of foot being liberally supplied 

 with nerves. The tentacles are specially sensitive, but I have not 

 been able to touch any part of the foot so lightly that it was not 

 immediately felt by the animal. In motion the animal depends 

 more on the sense of touch than on eyesight. 



Taste. There is no doubt that the animal possesses some sense 

 of taste, but, from long observation, I think that in the selection 

 of food the animal depends more on the sense of smell than that 

 of taste. 



Light. The eyes of both Helix and L i m a x are situated at 

 the extremity of the superior tentacles, and are conspicuous, hav- 

 ing the appearance of bright, black specks. Under a low power 

 can be seen the globular eyeball invested by a transparent tunic, 

 corresponding to the cornea; the crystalline lens lying under the 

 delicate cornea; the choroid, which forms two thirds of a sphere, 

 transparent and having a single layer of irregularly round or oval, 

 black pigment cells. P o 1 y gy r a is nocturnal in its habits, and 

 perhaps at that time it can see more clearly; but in all my experi- 

 ments with different individuals, many of them conducted with 

 only sufficient light to distinguish the animal, I have seen no evi- 



