224 LIFE, IN ITS INTERMEDIATE FORMS. 
order to see their affinity, nothing more would be needful 
than to detach a piece of the rock, and a fragment of the 
timber, each with one or more of its tenants adhering, and 
plunge both into a glass of sea-water. Presently you 
would see, within the open mouth of the cone, two little 
shelly pieces separate, and out comes a most exquisite 
apparatus. It is something like a hand of many slender 
fingers, thrust forth, opened, closed again with a clutch, 
and drawn in. 
Look now at the delicately coloured valves of the stalked 
kind. These separate, and a similar hand is thrust out, 
makes its clutch, and disappears. The structure of both, 
and the action, are the same. The principal differences 
are the absence of the footstalk in the former case, and 
the soldering together of the valves into a conical shape. 
The one represents the Acorn or Sessile Barnacles ( Bala - 
nidw), the other the Stalked Barnacles ( Lepadidce ). 
The “hand” thrown out is a beautifully adapted 
implement for the capture of prey. The Lepas, indeed, 
possesses in its footstalks a little more freedom of motion 
than the firmly-soldered Ba/amis ; but both are fixed, and 
are therefore incapable of pursuing their prey. They are 
hence dependent for subsistence on such minute animal- 
cules as the currents of the waters may bring within reach ; 
and the constantly recurring clutches help to increase 
these currents. But they do more. If we examine each 
of the long “fingers ” (cirri) which compose the hand, and 
which are set in expansible pairs, we shall see that it is 
composed of a great number of joints, whereby it is en- 
dowed with great flexibility, and that it is also studded 
with fine but stiff bristles, which stand out at right 
