234 THE ANNELIDA POLYCHAETA. 



pale, distally tapered processes extending but little beyond the middle of the 

 peristomium. Thej^ seem but vaguely and partially annulate. (Plate 53, fig. 1). 



The third and succeeding or parapodia-bearing somites are regular and 

 undivided. They are rather short, in the widest part of the body being eight 

 times wider than long. The dorsum is strongly convexly arched in the usual way, 

 a little depressed along the middorsal line and along each side toward the para- 

 podia. The anterior somites show a few weak longitudinal impressed lines. 

 The venter is flat; a weak vertical furrow is traceable except anteriorly and 

 posteriorly, the furrow more distinct over middle and caudal portions. The 

 pygidium is very short, slightly narrowed caudad and broadly obliquely truncate, 

 the anus being subdorsal in position. There are two anal cirri scarcely 

 exceeding a mm. in length, pale, gradually tapered and annulate, the annuli 

 short and not strongly marked; and in addition there are two more ventral 

 cirri, these being relatively minute and also indistinctly shortly annulate, one 

 inserted at base of each larger one on its ventral side. 



The parapodia are processes of moderate length, distally more or less 

 rounded, and having a slightly elliptical cross-section, the long diameter being 

 vertical, so that the parapodia appear somewhat compressed in an antero- 

 caudal direction, the most anterior ones, however, being more strictly cylindri- 

 cal, all narrowing distad. The first parapodium on each side is noticeably 

 reduced. The dorsal cirri arise from the bases of the parapodia. Each is a 

 moderately slender process thickest at base and gradually tapering to the nar- 

 rowly rounded distal end; it is annulate, the annuli being very short and usually 

 not strongly marked, or sometimes even vague. In the anterior region the 

 notocirri decidedly exceed the parapodia and setae; caudad they become more 

 slender and shorter. The ventral cirri in the anterior region consist of a cylindri- 

 cal, proximal article and a much shorter, abruptly narrower, distal article which 

 is a little narrowed distad and has the distal end rounded. The neurocirri of 

 the region a little exceed the parapodia. In the posterior region the neurocirri 

 are, as a whole, much less stout, conical processes, and toward the caudal end have 

 become markedly slender, with the apical portion long, thin, and uniform in 

 diameter, subfilamentous. In all parts the neurocirri remain longer than the 

 parapodia. 



The branchiae begin on the ninth somite (seventh parapodial) and occur 

 on all subsequent somites excepting the last six. The branchiae consist in all 

 cases of a single, slender, wholly unbranched filament. The filament is slightly 

 tapered from the base to a narrowly rounded extremity. The first branchia 



