ARRANGEMENT OF THE CIRRHIPEDES. 31 



part which is called the head is merely a slight eminence, 

 beneath which is a mouth furnished with lateral jaws. 

 Unlike all other annulose animals, this part is not at one 

 of the extremities ; for those organs which are called 

 the feet, are placed above the mouth, so that the latter, 

 properly speaking, is placed nearly beneath the body: 

 there are six of these feet-like organs on each side, each 

 consisting of a short stem, which is then divided into 

 two very long, jointed filaments, resembling the an- 

 tennae of insects, and fringed, especially at the end, with 

 fine hairs : in front of these is another, much longer 

 and thicker, which Poli calls a species of proboscis, and 

 which there is every reason to consider as analogous to 

 that organ in quadrupeds. M. Cuvier, indeed, objects 

 to this term, but leaves us quite in the dark as to its 

 real use. Poli, whose authority is of the greatest 

 weight, observes that the motion of the heart is dis- 

 tinctly visible.* To his invaluable work, and the me- 

 moirs of M. Cuvier, we must refer the scientific reader 

 for further details ; but the paper by sir Everard Home 

 upon these animals f scarcely deserves his attention, being 

 replete with errors. To Mr. Thompson's essay we shall 

 presently return. 



(28.) We shall not here attempt any natural ar- 

 rangement of these animals, but merely notice them as 

 they stand at present arranged in systems. The chief 

 divisions which have been made are two ; and these 

 have been called families. The first contains those 

 which are elevated upon a fleshy, flexible peduncle, and 

 are the true barnacles ; while the second is composed of 

 such as are attached by their shells only, and are conse- 

 quently sessile. Collectors generally call them acorn- 

 shells. These primary divisions, however, are arbitrary. 

 Among the true barnacles, or those provided with pe- 

 duncles, we find some entirely covered by shelly plates; 

 while others are either wholly destitute of such pro- 



* Test. Sic. i. 18. .t Phil. Trans. Ixxv. 410. 



