EVOLUTION OF INTELLIGENT BEHAVIOUR 157 
In most cases the individuals which failed to return to 
their respective scars took up new positions; and in several 
instances, when they were subsequently removed to a distance 
of a few inches from this new position, they returned to it. 
Their return to the scar was watched in many cases, and the 
course was fairly, but not quite direct. One limpet covered a 
distance of ten inches, over a somewhat curved course, in a 
little under twenty minutes. In another case the limpet on its 
return journey had to pass between two others, which necessi- 
tated the lifting of the shell to some height so as to clear one 
of them. On reaching the scar they twist and turn about so 
as to fit down in the normal position which is constant. When 
they come up the wrong way round they rotate pretty rapidly 
through the 180 degrees to get into position. One was 
observed to make a short excursion from and return to its scar 
under stillish water. But as a rule they seem to remain fixed 
when they are submerged, moving for the most part when the 
tide has just receded. 
The greatest distance I have watched a limpet reach from 
its home was twenty-two inches. But I have found them at a 
distance of three feet from their scars—that is to say, from 
those to which they fitted perfectly. This was on a large flat 
surface. 
When they move, the tentacles are projected out beyond 
the shell, and keep on touching and slightly adhering to the 
rock. On reaching the scar they carefully feel round it with 
the tentacles. By excision of these feelers Professor Davis was 
led to conclude that it is not through their instrumentality that 
the limpet finds its way back to its particular scar. But 
I am inclined to question these results. At any rate, further 
observations and experiments are needed to settle the point. 
Snails will also return to special dark hollows or crannies 
in the wall after their foraging excursions. Such behaviour 
in molluses affords evidence of something more than instinct. 
In popular speech, we should say that there is memory of the 
locality. And in any case it is difficult to interpret the facts 
ithout the assumption that the animals are conscious, and 
