LEPAS BARNACLE. 201 



Though dissimilar in their appearance, these 

 shells are united by many points of resemblance; 

 they are all more or less of a conical form, com- 

 posed of several valves, and are parasitical. The 

 animals inhabiting them are very similar, and 

 differ much from other ' mollusca. They have 

 no head or eyes, the mouth has jaws, with horny 

 laminae or erect teeth; but the most singular 

 part of their structure consists in the numerous 

 tentacular, curled, articulated arms ; these vary 

 in number, some of the species have as many as 

 twenty-four. They are arranged in pairs, and 

 are all inserted together ; the twelve longest are 

 erect and arched, appearing like curled feathers ; 

 they are clear and horny; each joint is furnished 

 with two rows of hairs on the concave side. 

 The animals make use of these organs to catch 

 their prey, and are continually extending and 

 contracting them. The twelve smallest are 

 placed in front, they are more flexible, and more 

 thickly set with hairs than the others. 



The sessile shells* are now formed into a 

 distinct genus called Balanus ; they adhere im- 

 mediately to marine substances at their base, and 

 remain immoveably fixed for life ; the form of 

 the shell is conical, and the valves of which it is 

 composed are so strongly cemented as almost to 

 appear like a single piece. From the construc- 

 tion of the shell, its immoveable walls, and its 

 large opening at the apex, the animal would 

 be in a very exposed and perilous situation, 



* Plate X. figure 6. 



