300 ANNULATA. 



louring, is one of the most splendid of all animals — the Aphrodita aculeata, 

 L.. It is oval, from six to eight inches in length, and from two to three in 

 breadth. The scales on its back are covered and concealed by a sort of stuff 

 resembling tow, which arises from the sides. From the latter also spring 

 groups of stout spines, which partly transfix the tow, and fasciculi of flexu- 

 ous setae of a splendid golden colour, whose changeable tints rival those of 

 the rainbow. They are not inferior in beauty to the plumage of the Hum- 

 mingbii'd, or to the lustre of the richest gems. Further down is a tubercle 

 from which arise three groups of spines, of as many different diameters, and 

 finally, a fleshy cone. There are forty of these tubercles on each side, and 

 between the two first are two small fleshy tentacida. There are fifteen 

 pairs of wide, and sometimes inflated scales on the back, and fifteen small 

 branchial crests on each side. 



PoLTNOE, Sav. 

 Where there is none of this tow on the back; they have five tentacula, 

 and their proboscis is furnished with strong and horny jaws. 



This is the only situation we can assign to a new and very singu- 

 lar genus which I call 



ChjEtopteeus, Cuv. 



The mouth has neither jaws nor proboscis, and is furnished above with a 

 lip to which are attached two tentacula. Next comes a disk with nine pairs 

 of feet, followed by a pair of long silky fasciculi resembling wings. The 

 lamellated branchiae are rather beneath the body than above it, and extend 

 along its middle. 



Chastopterus pergamentaceus, Cuv. This species, which is found at the 

 Antilles, is from eight to ten inches in length, and inhabits a tube resemb- 

 ling parchment. 



ORDER III. 



ABRANCHIATA. 



The Abranchiata have no apparent external organ of respiration 

 whatever, and appear to respire, some, like the Lumbrici, by the 

 entire surface of the skin, and others, like the Hirudines, by internal 

 cavities. They have a closed circulating system, usually filled with 

 red blood, and, like all the Annulata, a knotted nervous cord. 

 Some are also provided with setae which enable them to crawl, and 



