KEW : THE FACULTY OF HOMING IN GASTROPODS. 313 



hand, it seems strange that slugs — which I have always found restless 

 in captivity — should have remained for a fortnight in a vessel which 

 appears to have been uncovered. Mr. Gain is inclined to explain 

 this observation by supposing that the former abode was found 

 during a search for shelter, for, as he observes, slugs object to any 

 retreat in which they cannot find covering. 



SNAILS. 



Mr. Ashford informs me that for a long time he felt sure that the 

 homing faculty was possessed by snails from having observed the 

 same individual of the common snail {Helix asj>ersa), recognised by 

 its markings, occupying day after day the same spot as a mid-day 

 retreat ; the weather was favourable for foraging, and it had in all 

 probability gone forth at nights for food.* In 1884, he put 

 a colony of snails of this species to the test, and his experiments, 

 which are of a very definite and satisfactory kind, together with 

 facts observed in the same year by F. d'A. Furtado, fully confirm 

 observations made several years previously by Mr. Standen, and 

 prove beyond doubt that II. aspersa is able to find its way back to 

 chosen quarters. Mr. Standen's observations, details of which he 

 has kindly communicated, were made in 1872 : — 



I observed an immature H. aspersa in a hole about two inches [wide] by one 

 inch deep, in the smooth brick wall (a newly-built piece) of a relation's kitchen- 

 garden. This hole was four feet from the ground, and a piece of wood reared 

 against the wall, with one end in a luxuriant bed of miscellaneous garden herbs 

 and the other just touching the hole, was so thickly covered with slime tracks 

 that my attention was drawn to it, and I requested that the piece of wood should 

 be allowed to remain where it was until I could satisfy myself of its being the 

 snail's ladder. On going to look in the evening, I found the snail had come down 

 to feed, and in the morning it was in the hole again. This I repeatedly observed 

 during the summer, and the snail attained maturity and hibernated in the hole, 

 where I saw it the following Christmas. Afterwards it was destroyed by some 

 animal, probably a mouse, which had mounted the ladder so long used by the 

 snail as a road to its food. There were no other aspersas along this particular bit 

 of wall. 



Mr. Ashford has obligingly given me the following notes of his 

 observations on H. aspersa : — 



At noon on the 20th April, 1884 (I quote from memoranda made at the time), 

 I searched for some individuals of this species in their usual corners of concealment, 

 and after passing several clusters not numerous enough for my purpose, found 



* It would be unsafe to assume the presence of the homing faculty in a Gas- 

 tropod from the fact that individuals are noted day after day in the same place 

 without due regard to the habits of the animal. Professor Herdman, for instance, 

 had specimens of the small periwinkle {Littorina rndis) under observation for 

 a month at a time on rocks in Puffin Island, and found no sign of their having 

 moved. Six marked specimens were examined at intervals of from six to nine 

 hours during three days and nights (' Life Lore,' ii (1889), 4). 

 Oct. i8qo. 



