244 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 



dorsal and ventral fissures into two lobes, the margins of which 

 meet across the fissures both dorsally and ventrally, at the former 

 reflexed into and continuous with the margins of the fecal grooves. 

 Except ventrally, where it is produced into a pair of rather prom- 

 inent rounded lobes, it remains of even height, low and incon- 

 spicuous. 



Oral membranes partially folded, with a thickened lateral lobe. 

 Tentacles with a broad leaf -like base as long as wide and a some- 

 what longer terminal filament. 



Peristomium more elongated than usual and more exposed 

 owing to retraction of the collar. 



Thorax of nine segments, eight of which are setigerous, somewhat 

 depressed, especially anteriorly where the width is fully one-third 

 more than the depth. Segments well marked by deep furrows. 

 Dorsum flat, with prominent median fecal groove ending in a 

 deep anterior cleft; venter strongly convex. Ventral gland plates 

 not well marked but occupying the entire width of the venter, 

 the last one reduced to half the length of the segment. 



Abdomen of 49 and 57 segments in two specimens counted, 

 slender and terete, except posteriorly where it is slightly depressed 

 and the segments very short, finally tapering to the minute pygidiam 

 which bears a short, rounded cirrus on each side. There are no 

 abdominal ventral plates and the fecal groove is scarcely noticeable 

 in this region of the type, but both are better developed though 

 inconspicuous on the smaller cotype. 



Thoracic setse form very conspicuous glistening pale-yellow 

 fascicles placed at an unusually high dorsal level. Collar fascicles 

 placed even higher, and in form longer and narrower. The in- 

 dividually nearly colorless setse are of two kinds except on the 

 collar, those of the dorsalmost series longer, lanceolate with narrow 

 wings and acute tips; the remainder a ventral phalanx of five or 

 six rows of broadly ovate or nearly orbicular paddle-shaped setae 

 bearing a long, strong, terminal mucron. (Plate XVIII, fig. 43). 

 Abdominal setae tufts small and strictly lateral, the setse nearly 

 or quite alimbate, becoming very long and slender caudally. 



Thoracic tori short linear, transverse, a little ventrad of the 

 setse tufts. They bear slender crochets only. These have long, 

 slender, curved stems of less diameter than the setse, slender necks, 

 strong curved beaks and a long and broad but low crest of many 

 rows of teeth. (Plate XVIII, fig. 44). Abdominal uncini interme- 

 diate between the crochet and avicular type, very delicate, with 

 the base fading away into the muscles. 



Tubes soft and flexible, covered with fine mud except at the 

 base, where the worm is usually found, which is transparent. 

 They form clusters of several (about 20) attached by their basal ends. 



The type measures 57 mm. long of which the gills are 26 mm, 

 and the thorax 5.5 mm. long by 2 mm. wide, and has 66 segments 



