RINGED-WORMS. 209 



by the Annulata, he preferred to place these last at the top. We 

 are quite as ready to acknowledge that Articulates with articulate feet 

 form a single connected series, and would not therefore separate 

 them from each other; but we place the Annulata below the Insects, 

 not above the Crustaceans. This arrangement, formerly adopted by 

 us when it was less common, appears now to be generally received; 

 even by Frenchmen, as, for instance, MILNE EDWARDS. 



The body of ringed-worms is generally much elongated and 

 cylindrical; in some instances it is broader and oval. It is divided 

 by transverse folds into rings or girdles, which, in most species, are 

 very numerous, and in one and the same species may vary greatly 

 in number, at least when that number is very great. The common 

 Leech has about 100 such, Eunice gigantea above 400 ; in Phyllo- 

 doce laminosa SAV., AUDOUIN and MILNE EDWARDS found nearly 

 500 rings, whilst in other individuals of the same species there 

 were sometimes only 300. The integument is always soft, not 

 corneous, but some of them live in sheaths or shells, sometimes 

 compacted with bits of shell or grains of sand into a mosaic work 

 of considerable strength, and sometimes consisting of calcareous 

 matter, as in the genus Serpula. 



In some the head is not distinct from the succeeding rings of 

 the body. In others it is distinguished from the trunk by its 

 different form, and is provided with eyes and even with threads, 

 which many authors name Antennae, after the so-named parts in 

 Insects and Crustaceans; but they differ from these, and can be 

 pushed in and out like the horns or feelers on the head of snails. 

 The number of these feelers differs ; there are rarely more than five, 

 and some species have only a single thread of the kind. 



On the rings of the body spines or hairs are usually set, which 

 however may be entirely wanting in some, as in the leech. In 

 most the hairs or spines are placed upon minute lateral tubercles, 

 which may be considered as rudiments of feet. These rudimentary 

 feet are, however, never jointed as in insects. They are usually 

 divided into two parts, which may be named oars or fins; one on 

 the dorsal surface, another on the ventral surface (rame dorsale et 

 rame ventrale SAVIGNY). On each of these two projections a 

 bundle of hairs (setce) is set, of very different form ; and, besides this, 

 each projection has, as the rule, a conical spine that can be re- 

 tracted into its sheath and is called needle (acus). Moreover, at the 

 VOL. I. 14 



