160 PROCEEDINGS OF THE ACADEMY OF [Jan., 



leaf-like basal part folded longitudinally to form a groove, and the 

 terminal ^ attenuated. 



The complete specimen has 8 setigerous thoracic and 68 abdominal 

 somites. The body is nearl}' terete throughout and has a nearly uni- 

 form diameter, except at the posterior end. Anteriorly the parapodia 

 are not at all elevated, but become rather prominent posteriorly. 

 Except the peristomeum all somites have sharply defined ventral 

 plates. In one specimen all, and in the others all but the first 8, are 

 divided into 2 equal squares by a ventral groove. The pygidium has 

 the form of a slightly oblique welt-like fold, which bounds the anus 

 dorsally and laterally. The fsecal groove is well-marked ventrally from 

 the anus to the somite IX, on which it passes caudad of the ventral plate 

 to the right and then bends sharply forward and passes obliquely 

 anterior to the seta bmidle to the dorsum, where it disappears. 



All of the setae and uncini are of a pale glistening yellow color and 

 have the arrangement usual in the genus. The seta^ of II are all of 

 the winged capillary type, but differ in length, width of wing and degree 

 of curvature or bending. The more slender and regularly curved ones 

 are dorsal. The 7 succeeding thoracic somites bear both ca]>illary in 

 the dorsal and paddle-shaped setse in the ventral part of the bundles. 

 The former (fig. 3) have the characters just described, but the more 

 ventral ones exhibit transitions toward the broad form in the tendency 

 of the wing to widen and split into two divergent symmetrical plates. 

 The two kinds are, however, always distinct. The paddle-shaped 

 setse (fig. 5) are arranged in a short, close phalanx. They have rela- 

 tively stout, shghtly tapering, striated stems, with the short, broad 

 wings together forming a thin ovate expansion which tapers distall}' 

 into a mucronate tip, whose length equals the greatest Midth of the 

 blade and which is bent out of the plane of the latter. On the abdomi- 

 nal somites only capillary setae (fig. 4) again occur, and in graduallv 

 diminishing number. The more slender, elongated, nearly wingless 

 ones are usually paired with shorter broader ones. 



On the thoracic segments the uncinigerous tori are flush with the 

 surface of the body and bear the two kinds of uncini in parallel vertical 

 rows, the aviculae being anterior. On somite III there are 44 of each, 

 on VI 32, and a further reduced number on VIII. The avicular uncini 

 (fig. 41) have the slender posterior process aiid the erect portion equal 

 and meeting at a right angle; the breast nearly hemispherical; the 

 neck erect and straight; the beak moderately long, acute and straight. 

 and inclined sharply downward with the lower margin ])arallel to the 

 breast; the crest elevated and much subdivided, with about .5 distinct 



