224 



LIFE, IN ITS INTERMEDIATE FORMS. 



order to see their affinity, nothing mora 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- 

 niclce), 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 Balanus ; 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 



