ORDER CIRRHIPEDA SEDENTARIA. 



95 



pressed, and of a brownish hue. When in a state of 

 perfect repose, it resembles a very minute mussel, and 

 lies upon one of its sides at the bottom of the vessel of 

 sea-water in which it is placed. At this time all the 

 members of the animal are withdrawn within the shell, 

 which appears to be composed of two valves, united by 

 a hinge along the upper part of the back, and capable 

 of opening from one end to the other along the front, to 

 give occasional exit to the legs. The limbs are of two 

 descriptions ; namely, in front a large and very strong 

 pair, provided with a cup-like sucker and hooks, &c., and 

 at the hinder part of the body, six pair of swimming- 

 members, so articulated as to act in concert, and to give 

 a very forcible stroke to the water, so as to cause the 

 animal, when swimming, to advance by a succession of 

 bounds, after the manner of the water-flea. 



3 1 



Fig. 1. Larva of Barnacle, natural size. 



2. magnified, seen from above. 



3. higlily magnified, seen from side ; a, swim- 

 ming-members ; b, front limb, with sucker. 



4. Eye, much magnified. 



5. Perfect Young Barnacle, natural size. 

 6. • full gro^^'n. 



"The greatest peculiarity, however, in the structure 

 of this animal, is the eyes; which, although constantly 

 shielded by the valves of the shell, are placed on foot- 



