644 Marvels of the Universe 
rocks, for already half a century earlier Edward Lluyd had demonstrated that these remains belonged 
to animals, and were not the petrified stems and flowers of plants, as they were first supposed to be. 
He even pointed out their affinity to the Feather-star, a species of Starfish, which, though not 
“stalked” in its perfect form, is rooted like the Sea-lily, and has the same system of arms sup- 
ported by an internal skeleton of limestone joints. The discovery of the living specimen set all 
doubt at rest as to its animal nature, but it was long before its relationship with the Starfishes 
was acknowledged. The further discovery of a rooted species by G. O. Sars, in 1864, reawakened 
interest in the Sea-lily and was indirectly the cause of the Challenger expedition of 1872, which 
added very considerably to the present knowledge of this subject. 
Lluyd has been proved absolutely right. The Sea-lily is an animal, and it is nearly related to 
the Starfishes, with which the Feather- 
star is the connecting link. Although 
low down in the scale of life, it is a 
very intricate organism. In common 
with all the members of its great 
family, the Crinoid has the power of 
depositing lime in its soft tissues. The 
deposit is most abundant in the skin, 
and, as it were, coats it, so that in time 
the creature has built up a continuous 
skeleton. In some cases, as in the Sea- 
pens, this skeleton is inside ; in others, 
as in the Sea-urchins, it is to all intents 
and purposes formed on the outside ; 
and so it is in the Sea-lilies. The chief 
part of the Crinoid skeleton is the cup 
situated at the head of the long stalk 
and supporting the feathered arms. It 
contains the most important organs of 
the creature’s body. In the cover of 
the cup.is the mouth, and radiating 
from this mouth to the branched arms 
are grooved channels which convey the 
THE JOINTS OF THE SEA-LILY. food particles to the creature. This 
These joints are of exquisite workmanship. The sutures or grooves cup is composed of two circlets of five 
by which one segment fits into the other form varied and elaborate A 
patterns. These segments, here shown “‘end-on”’ to give some idea of plates. In some species two or more of 
their construction, are all taken from one species of Sea-lily, that shown these plates will unite to form a single 
on page 643. : es ae : 
plate, but their pentameral origin is dis- 
cernible. And here it should be noted that the whole creature is built up (like the Sea-urchins and 
Starfishes) on the principle of five. There are always five arms, however many times they may 
branch, and the internal organs can be roughly grouped into systems of five. 
The arms of the Sea-lily are very sensitive and highly-organized members. On the inner surface 
they are grooved for the purpose of carrying the continual stream of water swept down by the 
feathered arms to the creature's mouth; for the water holds the minute organisms on which the 
Sea-lily feeds. Beneath this groove lies a system of water-vessels, which create hydraulic pressure 
and control the movement of the limbs. There is also a nerve-system running the whole length of 
the arm and a system of blood-vessels. The exterior surface of the arm is formed of the same jointed 
material as are the stalk and the cup; each segment fits closely into its neighbour, either by means of 
sutures or grooved markings, on the ball-and-socket principle, or simply by a cohesion brought about 
