198 THE ANNELIDA POLYCHAETA. 



bulging out below this and extending into the long single tentacle. This ten- 

 tacle seems to correspond to the usual paired tentacles since it is bifui'cate at 

 the tip. The tentacle is a little less than three times as long as the prostomium 

 is high. The bifm'cation at the tip is somewhat variable, but never exceeds one 

 foiirth the total length. The tentacle increases in thickness proximad. It is 

 distinctly annulated or jointed throughout its length, the joints short and num- 

 erous. The palpi arise on the ventral sm-face immediately in front of the mouth 

 and project a little caudad of ventrad. Each in length is about equal to the 

 height of the prostomium and is conspicuously biarticulate, the proximal joint 

 thicker and stouter, with sometimes faint signs of a secondary joint proximally. 

 The distal joint is elliptic in outline, narrowly rounded distally. There are two 

 pau's of eyes. Of these the posterior ones are dorsolateral in position, each occu- 

 pying a caudolateral corner of the prostomium, with their axes directed ecto- 

 dorsad. They are nearly circular in outline and are about their diameter 

 apart. The anterior eyes are situated on the sides of the prostoiriium, each 

 cephaloventrad of the corresponding posterior eye and with the axis directed 

 ectad. They are decidedly smaller than the posterior ones and are less circular 

 in outline, being broadly obovate to subelliptic. All eyes are very strongly 

 convex. (Plate 28, fig. 6). 



The peristomium is decidedly longer than the prostomium and also clearly 

 exceeds the second somite. It is wider than the prostomium and projects much 

 below it. The border of the mouth is crossed radially by impressed lines or 

 wrinkles. There are four pairs of tentacular cirri, all those of each side being 

 attached close together between the eye and the mouth. The dorsal anterior 

 cirrus is largest of the four. It is in length but Uttle longer than the tentacle 

 and reached to the fourth somite or, in some, only to the third. The anterior 

 ventral tentacular cirrus is much shorter ; but it is stouter and somewhat longer 

 than the posterior ventral which, in tui'n, is longer than the posterior dorsal which 

 seems normally to differ in being of more uniform diameter and blunt distally. 

 The style of each cirrus is constricted at the base and attached tlirough the 

 mediiun of a short, narrow cirrophore. The cirri are all annulate or varicose 

 and all, except possibly the dorsal posterior ones, are conspicuously pointed 

 distad. A small, simple nuchal pit occurs on each side back of the eye and close 

 to the base of the upper posterior tentacular cirrus. (Plate 28, fig. 6). 



The succeeding or normal setigerous somites are all sharply separated from 

 each other. The anterior four or five are particularly highly convexly arched 

 above, and are also convexly but less strongly arched below. In the middle 



