CHAP, 1X. ] THE DEEP-SEA FAUNA. 437 
flattened calcareous joints; it may be snapped over 
at the point of junction between any two of these 
joints, and by slipping the point of a penknife into 
the next suture a single joint may be removed entire. 
The joint has a hole in the centre, through which 
one might pass a fine needle. This hole forms part 
of a canal filled during life with a gelatinous nutri- 
ent matter which runs through the whole length of 
the stem, branches in a complicated way through 
the plates of the cup, and finally passes through 
the axis of each of the joints of the arms, and of 
the ultimate pinnules which fringe them. On the 
upper and lower surfaces of the stem-joint there 
is a very graceful and characteristic figure of five 
radiating oval leaf-like spaces, each space surrounded 
by a border of minute alternate ridges and grooves. 
The ridges of the upper surface of a joint fit into 
the grooves of the lower surface of the joint above 
it; so that, though from being made up of many 
joints the stem admits of a certain amount of 
motion, that motion is very limited. 
As the border of each star-like figure exactly 
fits the border of the star above and below, the five 
leaflets within the border are likewise placed directly 
one above the other. Within these leaflets the 
limy matter which makes up the great bulk of the 
joint is more loosely arranged than it is outside, and 
five oval bands of strong fibres pass in the inter- 
spaces right through the joints, from joint to joint, 
from one end of the stem to the other. These 
fibrous bands give the column great strength. It 
is by no means easily broken even when dead and 
dry. They also, by their elasticity, admit a certain 
