58 ANIMAL INSTINCT AND INTELLIGENCE 
traversed being often very irregular and covered with acorn- 
barnacles. When the animal gets back to the scar it of course 
arrives wrong way on, so to speak, and it quickly shuffles round 
so as to get into the proper position. A memory of locality 
certainly exists, and this would seem to imply intelligence. In 
the course of time a Limpet acquires a very accurate knowledge 
of the topography of a fair-sized area around its home, and if 
picked up when on the crawl and placed within this area is able 
to get home, though the time taken varies considerably. Exactly 
how it gets home we do not know. The simple cup-like eyes 
cannot render assistance, nor can we very well suppose that the 
otocysts help to guide it. Experiments appear to demonstrate 
that the animal does not smell its way back, and we are there- 
fore reduced to touch, or to a “locality sense”, or to both. The 
most obvious organs of touch are the two large tentacles on 
the head, with which the Limpet constantly touches the rock as 
it crawls, and it is no doubt by means of these that a good 
deal of the topographical knowledge is acquired. But as it can 
get home without the aid of these organs there must be some 
other organs of guidance. The edge of the mantle-flap is pro- 
vided with a very large number of small tentacles which can be 
stretched out and actively moved, as they are sometimes, if not 
always, when the animal is adjusting itself on its scar. These 
perhaps have something to do with the matter, and so may still 
other sense-organs, but further investigation is required. The 
problem here to be solved, like most of those connected with 
locality-knowledge, is of a particularly baffling kind, though not 
to be regarded as insoluble. The Garden-Snail (Helix aspersa) is 
another Mollusc possessed of a “homing instinct ” 
INSTINCT AND INTELLIGENCE IN VERTEBRATES 
(VERTEBRATA) 
There is here an almost unlimited amount of material which 
might be discussed, but a few examples must suffice. 
Warninc CoLoration.—A large number of animals pos- 
sessed of noxious properties advertise their objectionable nature 
by means of bright though somewhat crude colours, and simple 
but striking patterns, the net result of which is to render 
them extremely conspicuous (see vol. ii, p. 301). Such are the 
