115 



The body is divided into about twenty-four principal rings 

 {segment a) ^ the first seventeen of which are distinguished by as 

 many narrow, elevated, circular ridges, more strongly marked 

 above than below. Before the first of these ridges there are 

 three secondary rings (annuU) ; between the first and second 

 there are also three; between the second and third, and the re- 

 maining ridges there are four, or rarely five. The ridges of the 

 first six rings bear on each side of the back a small pencil of 

 setse, consisting of two flattened brushes, of which the anterior 

 is much shorter than the posterior. These pencils gradually 

 increase in size posteriorly, and each is placed in a membranous 

 sheath, which is retractile. ' The uncinate setae are placed in an 

 elongated row on the side of the ridge beneath the sheath of the 

 superior ones. 



The ridges of the next eleven rings bear not only the setae of 

 two kinds, .but also the branchial tufts, which are largest on the 

 middle rings, and very small on the first, — increasing in size 

 posteriorly. These branchiae are highly contractile, and when 

 expanded, extend in the form of a semicircle from a cavity on the 

 inner side of, and posterior to, the pencil of setse. Their semi 

 circular base consists, in the larger tufts, of about twenty main 

 tubes joining each other laterally ; these tubes then diverge and 

 give off branches, the chief of which are alternate on the sides 

 of the main trunk. The branching is then continued indefinitely. 



The posterior rings of the body are not so distinctly marked 

 with ridges as the anterior ones, and bear neither setse nor 

 branchiae ; but they usually present a variable number of short, 

 thick, cutaneous processes, of the same color as the body. The 

 thickness of the body is nearly the same throughout, there being 

 no anterior enlargement, as is seen in the European species. 

 The proboscis is short, covered with small papillae, which have 

 their abrupt sides presented outward or backward, and are 

 arranged in very regular longitudinal rows, about twenty-four in 

 number. The color of the animal is a rich, dark green, of vari- 

 ous shades, often approaching to brown on the middle of the body. 

 A dark-colored median line extends along the ventral surface. 

 The circular ridges are of a light brown color; the setae of a 

 bright golden hue; the branchiae, dark crimson; and the pro- 

 boscis, reddish-brown. 



