WORMS. 
137 
collar, and arranged somewhat like two petals of a flower, 
with a deep bend or sinuosity where they unite. 
The extreme beauty of the display cannot but elicit 
our admiration ; wo raise a Auger to point out some par- 
ticular item to a companion, when, lo ! the whole apparatus 
disappears like a vision : with the speed of thought the 
whole has been retracted into the pipe, the stopper enter- 
ing last of all, and tightly closing the aperture. 
Our friend Serpula is an exceedingly prudent personage, 
and will not soon ernorge fro m his strong castle again, 
after receiving such a fright as the lifted Anger gave to 
his sensitive ganglia \ and when he does, it will not be 
without great caution. Meanwhile, as we are waiting his 
reappearance, wo will briefly discuss some points of his 
organisation. 
Those beautiful fan-shaped petals are gills, the breathing 
organs of the animal, whereby he derives from the sea- 
water the oxygen necessary for the renewal of the blood, 
which is constantly exhausted in the buildiug-up of the 
various tissues. Their situation at the anterior extremity 
of the body is a wise provision, since they can by this 
arrangement be periodically bathed in the suiTounding 
water, with the least possible exposure of the animal. 
In other species, however, which do not inhabit tubes, the 
gills are situated on other parts of the body. Thus in the 
common Lug ( Arenicola ), or Mud-worm, so well known to 
every fisherman for its value as bait, the gills form little 
tufts of a crimson hue on the rings of the middle part 
only. While on the exquisite Leaf-worms ( Phyllodoce ) 
they resemble heart-shaped leaves, arranged in a row on 
each side throughout the entire length. 
