bending their arms into S-like 
curves after the fashion of a 
snake. Ofcourse, if all the 
arms wriggled in the same 
manner at the same time, there 
would be no progress in any 
direction ; but a distinct order 
in their movements is observed. 
Two of the arms arrange them- 
selves as nearly parallel as 
possible, and curve their slender 
tips away from each other, so 
enabling them to get a grip 
upon the sand. Then by form- 
ing another curve farther back 
simultaneously, they drag the 
disc forward. The three other 
arms, pressing with their tips 
upon the sand, straighten out 
their previously-formed curves 
and so push the disc forwards. 
By this correspondence in the 
movements of the arms the 
Brittle-star can wriggle along 
with considerable rapidity. 
These Brittle-stars, as their 
name indicates, are very touchy 
individuals, and manifest their 
annoyance at any interference 
by snapping off their arms as 
readily as a slow-worm or a 
lizard snaps off its tail. This 
is often a means of saving their 
lives. A fish or a crab comes 
along and seizes our Brittle- 
star by an arm—for one arm 
or another is always nearer 
than the disc—and the Brittle- 
star cheerfully relinquishes it 
and makes haste to wriggle 
Marvels of the Universe O11 
Photo by permission of ] [R. Ludekker, F.R.S. 
THE BARK-GECKO. 
The Bark-Gecko is a native of Madagascar, and is about eight or nine inches in 
length. It has a large, flattened head, depressed body and short, trowel-like tail, with 
the toes terminating in large discs, which enable it to cling to the bark of a tree. 
When thus posed its markings and colour are identical with the lichen-clad bark, and 
so it is enabled to escape detection. 
away while his enemy is eating up the discarded member. The Brittle-star, like Sea-stars in 
general, can easily grow another arm to replace the lost one. It is no uncommon experience to 
meet with individuals thus mutilated—in fact, if you are in want of perfect specimens for the 
cabinet, it is extremely difficult 
to obtain them, because if they are perfect when you determine 
upon the one you will have, the probability is that it will go to pieces before you have secured it. 
Our last example of the diversity of forms in these Sea-stars is the Shetland Argus, in which 
the disc is obscurely five-sided, 
with ten ridges on its upper surface. The five arms are very long, 
and immediately after they leave the disc they divide into two branches. and these again branch 
into two, and so on almost ad infinitum. These branches are very flexible, and cling round weeds 
