[21] ANNELIDS OF PEOVINCETOWN, MASS. 71& 



Buccal segment a little longer than the second segment. 



Tentacular cirri with long cylindrical basal articles, the posterior 

 superior cirrus reaching about to the fourth segment, the others shorter, 

 as shown in the figure. 



The dorsal cirri arise from the base of the lingula. On the anterior 

 segments this cirrus is as long as its lingula; it grows progressively 

 shorter to the tenth segment (fig. 39), after which it again lengthens,, 

 becoming longer than the lingula on the middle and posterior segments. 



The superior lingula and single lip of the dorsal ramus are alike in 

 all respects; stout, conical, close together on the anterior segments, 

 shorter and more divergent behind. 



The ventral ramus has but one lip, is shorter and wider than the 

 dorsal, somewhat flattened in front, with the lower margin concave 

 near the apex, but further back tapering regularly. 



The ventral lingula is a little shorter than the upper lingula, in all 

 other respects similar to it; on the posterior segments (fig. 40) turned 

 downwards. 



The ventral cirrus arises from a small elevation at the base of the 

 ventral lingula; on the anterior segments fusiform (fig. 39), further 

 back (fig. 40) more regularly conical. 



The setse are of three kinds (figs. 41, 42, 43). Those of the upper 

 ramus are short, hardly reaching beyond the ramus, appendix very 

 delicate, terminal points of stem of same length (fig. 41). Those of the 

 lower ramus in two bundles ; in the upper part of the upper bundle the 

 setae are the same as those described above (fig. 41); in the lower part 

 of the same bundle a few with short appendix (falcate), curved near the 

 end, apex bluntly rounded (fig. 43); in the lower bundle, anterior seg- 

 ments, many like fig. 43, a few like fig. 42 ; further back the falcate setse 

 become less numerous. In the single specimen found the setae of the 

 dorsal rami, after the first few segments, had all been lost. At first 

 there is a single black acicula in each ramus; further back a second 

 acicula, slender, uncolored, appears in the dorsal ramus. 



The body was colorless except as colored by the blood, which showed 

 through very plainly; bases of feet opaque white, this color being due 

 to glands within them. 



Length, 45™™. 



Width, 1. 2™™. 



Posterior third tapering a trifle. This is the most delicate Nereis 

 described from our coast. It is easily recognized by its extreme nar- 

 rowness as compared with its length. 



But one specimen was taken, off Eace Run, near Provincetown ; 20 to 



