350 THE LIVING ANIMALS OL THE WORLD 
of the class. Thus, in the COMMON 
Star-fisii. there are five so-called arms, 
five eye-spots, one at the tip of each 
arm, and five equivalent elemental 
components of all the more impor- 
tant viscera. In the Se.\-cucumber.S, 
which have elongate worm-like bodies, 
there is a similar apportionment of 
the nerves and muscles of the body 
generally into fives, and also of the 
branching tentacles which surround 
the mouth. Tubular locomotive organs, 
the so-called “ tube-feet,” are common 
to all the three types enumerated. 
The calcareous plates and spinules, 
while attaining to a maximum develop- 
ment in the urchins, are also abundantly 
represented in the other groups. In 
the common star-fish these calcareous 
elements form within the skin an 
openly reticulated trellis-like frame- 
work, while in the ordinary sea- 
cucumbers they more usually take the form of innumerable microscopically minute spicules. 
The two less familiarly known groups of the Fe.\TIIER-STARS and BrittlE-SIWRS fully agree 
with the previously enumerated types in their five-fold structural composition. The brittle- 
stars have almost invariably five arms only, but they are independent outgrowths from the 
body proper, instead of being prolongations of it, as in the common star-fish. 
The Feather-stars, which include some of the rarest and most beautiful representatives 
of the group, are mostly inhabitants of deep water, and remarkable for the circumstance that 
either throughout life or in their early phases they are affi.xed to submarine objects by slender 
stalks. This peculiarity imparts to the animals such a flower-like aspect that, in conjunction 
with the indurated calcareous nature of their skeletons, they have received the title of 
” Stone-lilies.” This appellation, however, was originally more particularly applied to their 
fossilised remains, which occur in remarkable abundance in the older geological strata. 
The most familiar representative of the group is the Rosy Fe.\THER-ST.\r, occasionally 
obtained among seaweed in rock-pools on the southern coast, but more often brought up with 
the dredge from deeper water. In this form the elongate feather-like arms radiate from the 
central, relatively small, five-rayed body. There is no supporting foot-stalk in this adult stage, 
the animal being freely movable, and clinging to seaweeds and other objects by means of a 
cluster of claw-like filaments developed upon its under-surface. Releasing its hold upon 
its temporarily selected position, it can crawl about with the aid of the hooked e.xtremities of 
its arms and their radiating joints. It can also propel itself through the water in a somewhat 
clumsy fashion by the consecutive flexion and extension of these appendages. This freedom 
of locomotion was not, however, always possessed by the feather-star. In its early days, and 
when of very small size, it was affixed to a slender foot-stalk, and dependent for its food on 
the animalcules and other minute organisms which drifted or swam within reach of its extended 
arms. The rosy feather-star takes its name from the bright rose-red tints by which it is 
usually characterised. Individuals of the species are, however, subject to considerable colour- 
variation. On the Australian coast, where many forms are abundantly represented, examples 
tinted deep crimson, black, bright golden yellow, or sundry admixtures of these several hues 
are not uncommonly found associated among a dredge-haul of these elegant sea-stars. 
The Permanently Stalked Stone-lilies are at the present day of rare occurrence. Up 
Photo by fV. Saville-Kent^ \_Milford‘on-Sea 
THICK-SPINED SEA-URCHIN 
In large specimens the spines are as thick as a slate-pencil, and may he used 
for the same purpose 
