No. 104.] 141 



third segment, or sometimes to its posterior margin ; the lower 

 posterior cirrus and the upper anterior equal, from one-fourth to 

 one-third shorter than the longest; lower anterior cirrus shortest; 

 viewed from below, this cirrus is seen to arise much below the others. 



The tirst two setigerous segments have no dorsal rami (hg. 26), 

 but the cirri lingulie and ventral ramus have nearly the same form 

 as on the segments following. From the fourth to twentieth- 

 twentj-fifth segment (tig. 27), the dorsal ramus, is small, conical, 

 distinct from its lingula ; the lingula is longer than the dorsal ramus, 

 broad at base, tapering gradually, apex bluntly rounded, somewhat 

 compressed ; the dorsal ramus has two lips, anterior and posterior ; 

 anterior small, of uniform diameter, directed upward ; posterior 

 larger than anterior, shaped much like upper lingula, but smaller, 

 directed outward ; the lower ramus has also two lips, placed one be- 

 hind the other, stout, bluntly conical, anterior turned outward, pos- 

 terior a little downward ; the inferior lingula is a little stouter at 

 base than the lips of the ventral ramus, otherwise about the same 

 form and size ; the ventral cirrus is longer than the dorsal, fusiform, 

 reaches to the middle of its lingula, arising some distance below it. 



Further back the basal part of the feet gains in length (fig. 28) ; 

 the dorsal cirrus becomes shorter ; the upper lingula longer, conical, 

 with less diameter ; the anterior lip of each ramus becomes gradu- 

 ally smaller, and finally disappears ; the lower lingula is greatly 

 reduced in size ; the ventral cirrus recedes from its lingula, becoming 

 minute, conical. 



On the posterior feet (fig. 29), the dorsal cirrus arises from the 

 base of the upper lingula; the remaining (posterior) lip of the upper 

 ramus becomes delicate, conical, reaching beyond the lingula. 



The anal segment (fig. 30) has a slightly crenulated margin ; its 

 cirri are delicate, their length more than double that of the longest 

 tentacular cirrus. 



Setna of two kinds ; one, with long narrow appendix (fig. 31), one 

 edge minutely denticulated ; the other (fig. 32) with short appendix, 

 one margin thickened and rounded, the opposite margin very thin, 

 somewhat coarsely denticulated ; those of the second form are found 

 only in the lower bundle of the ventral rami, after the first twenty 

 to thirty segments, from four to six in each bundle, always accom- 

 panied by some of the first form. 



Color, light flesh-color to reddish-brown ; dorsal cirri and superior 

 lingulae pure gleaming white, other parts of the feet also white; 

 head, esjDecially its posterior half, usually darker than the body. 



Body elongate, widest at the eighth segment, diminishing rapidly 

 forward, uniformly but very gradually backward. 



This species forms a tough membraneous tube, in color dark red- 

 dish-brown, fitting the body very closely. 



Length of one specimen (140 segments) 60™™; width with feet 

 4mm. without feet, 2™™; length of a larger specimen, 75™™; width 

 with feet, 5™™. 



Two specimens kept in well-water, not at all brackish, for forty- 



