STRUCTURE OF THE BARNACLE. 23 



of the body, at the commencement of the opening in 

 the shell- covered mantle through which the tenta- 

 cula pass. It terminates an elevation or raised tuber- 

 cle ; it presents a lip, furnished with minute palpi, 

 or feelers, and three pairs of mandibles, or seizing 

 organs, of which the two external are horny and ser- 

 rated ; the third pair are soft. Between the mouth and 

 the stems of the tentacula are certain small fleshy ap- 

 pendages of a conical figure, and so arranged as to 

 resemble a minute star-fish ; these are supposed to 

 be the respiratory, or rather aerating organs. From 

 the mouth, a short oesophagus, of firm texture, leads to 

 a capacious stomach, imbedded in a glandular mass, 

 which is the liver. The intestinal tube is simple ; it 

 is large at the beginning, and runs, becoming narrower 

 as it proceeds, along the dorsal aspect of the body, 

 terminating at the base of the ovipositor. There are 

 no eyes, nor organs of hearing. 



The figure on the next page represents the animal 

 with the two lateral shells removed; the tentacula of one 

 side are cut away to show the form of the conical termi- 

 nation of the body, a is the body partly invested 

 with its mantle ; beneath which latter, and arising 

 from it, is shown the origin of a muscle, b, which 

 spreads over the entire surface of the body, and sends 



