262 MOLLUSCA. 



leathery membrane, which at the lower end is pro- 

 longed into a foot-stalk, sometimes many inches 

 in length, endowed, notwithstanding its stiffness, 

 with a considerable power of flexion. The valves, 

 closed for the greatest part of their circumference, 

 have a narrow opening in front, through which are 

 protruded twenty-four jointed arms, (cirri,) ele- 

 gantly curved, and fringed with stiff hairs at every 

 joint. These arms are arranged in pairs, six pairs 

 being on each side, and each pair proceeding from 

 a single stem ; the upper ones are longest, gradually 

 diminishing downwards. At the bottom is placed 

 the mouth, furnished with three pairs of jaws. The 

 Barnacles are found attached to solid substances im- 

 mersed in the sea, such as floating timber, the bot- 

 toms of ships, and even (as in a case recently brought 

 to our notice) the bodies of living Whales. When 

 a living Barnacle is examined under water, its mo- 

 tions are peculiarly pleasing, the whole array of 

 the twenty-four cirri are suddenly thrown out, and 

 instantly drawn back into the most elegant curves 

 with great rapidity ; and thus produce a constant 

 current, and form an effective casting net, by which 

 any animalcules floating within reach are entangled 

 and sucked into the mouth. From some investi- 

 gations lately made by Mr. Thompson, it appears 

 that these animals undergo a real transformation, 

 a circumstance which would still more closely ally 

 them to the Crustaceans. The young Cirrhopod is 

 stated to be capable of swimming freely about like 

 the minute Waterflea, (Daphnia,) having six pairs 



