Marvels of the Universe 1123 
This burrow is excavated chiefly by means of the third pair of legs. Mr. Say, describing an 
American relative of this species, says that he found the burrows proper about eighteen inches below 
the surface of the sand, communicating with the water by a more or less vertical tube which finished 
off above the sand level with a sort of chimney. These tubes and burrows do not collapse, as might 
be expected, when the excavator is not at home or is dead. The constant pressure of use, and 
possibly some exudation from the Shrimp’s body, causes the sand to become indurated, so that when, 
after the decease of the architect, they fill up 
with sand from the entrance, they can still be 
traced by these indurated walls and the little 
chimney at the top. 
Gebia, the Mud-borer, is much like the 
Mud-burrower, but has not such _ finely- 
developed “hands.” It is a yellowish-white 
Shrimp, ornamented with star-shaped orange 
spots. Sometimes it saves itself the trouble of 
doing its burrowing for itself by occupying the 
vacated burrows of the Razor-shell. 
Leach’s Shrimp, or the Variable Shrimp as 
it is sometimes called, is more shrimp-like than 
some of the species we have mentioned. A 
rather abrupt bending of the hind-body gives 
it something of a hump-backed appearance. 
It is chiefly worthy of note because of the 
quick-change power it possesses. It is common 
in rock-pools on our own coasts, but is not 
easily seen by the uninitiated by reason of this 
trick of changing colour to suit its environ- 
ment. If a red Shrimp is swimming between 
your eye and some red seaweeds, it is not easily 
seen, and if in the course of its swimming it 
comes among green weeds, though for a moment 
it is well contrasted with its background, it 
at once begins to disappear by turning green. 
It may, in fact, be almost any colour according 
to circumstances—red, pink, salmon, emerald- 
green, cobalt-blue, grey, chocolate or white. é PENCE Ree REP il CREST : 
These colour-changes are most marked in the Photo vy] : [B. Step, F.L.8. 
4 THE MUD-BURROWER. 
younger specimens. When it grows old and IN ayer URE aE AEE Ee ener 
possibly settles down to some particular station, in a burrow and uses its larger pincer-claw to block the 
it appears to have a colour-pattern which has 
become fixed in relation to its environment, for mature individuals from different situations, though 
they will be found to differ remarkably one from another, have lost the power of changing when 
artificially introduced to new surroundings. 
entrance. 
An interesting group are the Skeleton Screw-shrimps, quite small creatures, whose bodies are 
slender and thread-like and give one the idea that he is looking merely at the backbone of some small 
creature to which a few of the limbs have remained attached. Gather a bunch of the small lime- 
encrusted weeds known as corallines from any pool and examine it in a basin of sea-water, and after 
a time you will see some of these Skeleton Shrimps sprawling in an ungainly fashion over the branches, 
which they closely resemble in form and colour, Their climbing is accomplished by three pairs of 
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