254 BARNACLES. 



parallel longitudinal lines. That these fibres are muscular 

 we may conclude from the animal having the power of 

 contracting the stem, or of twisting it in various directions. 

 Within the tube there is a fluid secretion. 



The shell is composed of five pieces, four of which are 

 lateral, two on each side ; while between the valves down the 

 back is interposed a single narrow slip uniting them together. 

 Their colour is white, more or less tinged with purplish blue. 

 Along the anterior margin the valves are but partially 

 connected by a membrane, leaving a large fissure, through 

 which emerge the plumose and jointed arms or cirrhi. 



The food of the Barnacles consists of small crustacea and 

 mollusca. These are entangled by the many-jointed plu- 

 mose cirrhi, which are perpetually thrown out and folded 

 again, so as to serve the purpose of a casting-net, and drag 

 the prey to the mouth, where it is seized and crushed. 



With regard to the reproduction of these creatures, the 

 eggs are seen enclosed at certain times within the hollow 

 of the peduncle, where they appear of a blue colour, and 

 render the pedicle opaque ; from this they pass through a 

 minute conduit into the cavity of the mantle, where they 

 are arranged like two leaflets, attached to the septum 

 between the body and the peduncle. They are enclosed 

 in a film, out of which they fall when ready to hatch. 



It is a remarkable fact, as we learn from Mr. 

 Thompson*, that the young barnacles and other cirrhi- 



* " Philosophical Transactions," I.e. 



