307 

 THE FACULTY OF HOMING IN GASTROPODS. 



H. WALLIS KEW, F.E.S., .M.C.S., 

 Loinion. 



The Limpet {Patella vulgata) is known to return regularly to its scar 

 after feeding. Three species of Liniax — the Yellow, Great Grey, 

 and Tree Slugs— and two of Helix — the Roman and Common 

 Snails — have been observed to return to special places. It cannot 

 be assumed, however, that every slug or snail seen crawling out in 

 the evening has a fixed home to which it will return. Limpets, it 

 would appear, do not wander far. 



Mr. Romanes, in considering certain observations of Mr. Hawk- 

 shaw, concludes that the Common Limpet is able to remember 

 direction and locality with precision, and thinks accurate memory of 

 •direction and locality by a snail for twenty-four hours is apparently 

 indicated by an observation of Mr. Lonsdale.* A gastropod is thus 

 accredited with the power of forming and retaining a mental picture 

 of the special place or home to which it returns, and with memory 

 of direction or the retention of a general impression of its bearings.t 

 From the nature of the eyes it is hardly likely that the formation of 

 this mental picture can be connected with vision ; the eyes of the 

 hmpet for instance are described as examples of the most primitive 

 kind of eye in the molluscan series, J and of course the mental image 

 which this animal retains of its scar ' cannot be supposed to be 

 comparable in point of vividness or complexity with the mental image 

 that a horse retains of its stall, or a dog of its kennel ; still such as 

 it is, it is a mental image,' and betokens what Mr. Romanes defines 

 as imagination in the lowest possible phase of its development.§ 



By some this view will doubtless be regarded as implying greater 

 mental activity than can be reasonably expected in a group so low 

 in the scale, and such will probably attribute the homing of limpets 

 and certain slugs and snails to the existence of some mysterious 

 additional sense, or will perhaps, be content to say, as Mr. Gosse has 

 done in regard to Patella^ that a gastropod returns to its home by 

 means of an ' infallible instinct. '|| A homing faculty of an extra- 

 ordinary degree of development is exhibited by many domesticated 

 mammals and birds, which have often been known to return to 

 their homes after having been carried many miles by rail or otherwise 

 in closed boxes or at night and set down in unknown districts. 



* ' Animal Intelligence,' pp. 27-29. 



t See Mental Evolution in Animals,' pp. 146, 153, etc. 



X E. Ray Lankester, Art. Mollusca, Ency. Brit., xvi {1883), p. 648. 



§ ' Mental Evolution,' p. 153. 



' P. H . Goss, ' Mollusca,' 1S54, p. 53. 



Oct. 1S90. 



