IN HIGHER INVERTEBRATES 57 
with painful sensations. Other Octopi manifested still greater 
intelligence, for they pulled hermits out of their shells, taking care 
not to touch the zoophytes, realizing apparently that these were 
the stinging element. More remarkable than this is an observation 
made by Madame Jeannette Power. This lady on one occasion 
saw an Octopus, that held a stone by one of its arms, watching a 
large bivalve (Pzxua) of which the shell was beginning to open. 
When this operation was complete the Octopus quickly inserted 
fda 
Fig. 1062.—A Limpet (Patella vulgata) leaving its Scar at Ebb-tide 
the stone between the valves so as to prevent them from coming 
together again, and then proceeded to make a meal of the helpless 
bivalve. 
Some of the Gastropods possess a well-marked “ homing 
instinct”, a particularly good example of this being afforded by 
the Common Limpet (Patella vulgata, fig. 1062). As elsewhere 
described (see vol. ii, p. 197) this creature lives on a particular 
spot, which in course of time becomes a more or less well- 
marked “scar”, to which it can hold so firmly as to defy waves 
and tide. From this home it wanders out to feed when un- 
covered by the water, and also when well covered. From such 
excursions, which may extend to a distance of several feet, it 
later on returns to settle down again on the scar, the surface 
