68 
the South Australian Naturalist 
beneath the mud and in a trice the hinder part of the body is 
buried. The chelipeds asssit in “working” the animals further 
down; the motions of these limbs suggest that the creature is 
clasping silt towards its chest and then thrusting it outwards 
When the crab is buried the only visible parts are the front the 
eyes, and the blackish antennules, which dart rapidly in and out 
and waggle industriously; the last-named appendages, by their 
constant movement, apparently assist in keeping the inhalent res- 
piratory openings free of sand which washes over the exposed 
front with each tiny wave. 
One of the functions of the long and attenuated hands of 
this Pebble-crab is apparent when one observes the creature 
search for its food. The crab runs quickly about in the shallow 
water and is continually pushing its arms down into the soft mud, 
or beneath pebbles, and feeling for edible material. In this 
way it secures pieces of marine worms, pincer-limbs of Snapping- 
prawns (Synalpheus) and fragments of other burrowing inverte- 
brates. Many marine worms break themselves into pieces when 
disturbed, while the Snapping-prawns, like Dickens’ lobsters (1) 
“part with a claw with as little concern as a man tearing the 
tail of his coat in a hedge when a mad bull is; after him.” In 
parts of the Bay, crowds of the crabs search for food together 
and in these circumstances the behaviour of a crab which secures 
a fragment of food Is ludicrous; the fortunate seeker tests the 
edible properties of his capture and immediately commences to 
consume it, at the same time making off at full speed, with a pack 
of friends at his heels making earnest endeavours to rob him of 
his meal. If the pursuers are numerous the diner is very soon 
robbed and in turn joins the hunters In an effort to recapture the 
coveted morsel. 
It may be well to mention to members of our Section that the 
observation, for the first time, of the behaviour of certain crus- 
taceans, in particular the crabs, conveys an irresistible impression 
that at least some of their actions are the result of reasoning. 
The behaviour of a river crab in dealing with a pebble encounter- 
ed while excavating is noted in a previous number of this publica- 
tion (2); this crab appeared to act with intelligence. One has 
to remember, however, that invertebrates, — even the higher in- 
vertebrates, such as insects and crustaceans — do not “think”, 
and cannot claim to be “Intelligent” as we understand the term 
they have a limited capacity^ for learning and their behaviour is 
largely governed by Ingrained instincts, which leads them to react 
purely mechanically to various sensations and influences. This 
