566 PROCEEDINGS OF THE ACADEMY OF [July, 



The thoracic setigerous tubercles have short bases but project promi- 

 nently. The tori are very long, the first about twice and the last about 

 1^ times the ventral interspace, the others intermediate. On the abdo- 

 men the same parts are little elevated and placed at nearly the same 

 level as the dorsal end of tlie last thoracic. The setigerous line is 

 shorter than the thoracic and the first torus about j as long as the last 

 thoracic. About 90 avicula? and the same mmiber of pick-shaped setae 

 occur on the torus of III and 60 of each on IX. On the thoracic seg- 

 ments the spatulate setse are very numerous and arranged in 5 or 6 ver- 

 tical rows, wdiile the capillary setse do not exceed about 15. The capil- 

 lary abdominal seta are in two regular rows of about 10 each on the 

 anterior segments. 



All of the collar setae and the dorsalmost setae on the other thoracic 

 segments are rather short, stout, capillary, tapered to an acute tip, 

 little curved and with small, nearly symmetrical wings with very fine 

 oblique strise on each side. The spatulate setse (fig. 24) have stout 

 stems and rather long, narrow curved blades about 2^ times as long as 

 wide with apical arms of moderate length. The abdominal setse of 

 both rows do not differ greatly in length. They are longer than the 

 thoracic capillary setse, especially posteriorly, and are gracefully curved 

 and tapered, with fairly broad, oblique, strongly striated and nearly 

 symmetrical wings (fig. 23). Avicular uncini are nearly uniform in 

 size and form on all thoracic segments. They (fig. 25) have moder- 

 ately long ciu-ved bodies, full breasts, slender upright necks, elevated 

 crests and slender acute beaks. Abdominal avicular uncini (fig. 26) 

 are smaller and have very small bodies and deeper breasts but are other- 

 wise similar. The pick-shaped thoracic setae have the form shown in 

 fig. 27. 



Pigment is totally absent from the body and on the branchiae exists 

 only as six regular, narrow zones of pale reddish-brown, chiefly confined 

 to the basal halves of the barbs and scarcely apparent on the stems. 



The tubes are nearly straight, thick, pale brown and A^ery little 

 incrusted with sand or other foreign matter. 



Known only from t\A"o large specimens taken at station 4,245, 

 Kasaan Bay, Prince of Wales Island, June 11, 1903, in 9o-9S fathoms, 

 on a bottom of dark green mud and sand mixed with shell and rock 

 fragments. 



Pseudopotamilla anoculata ep. nov. pi. XXXVII, figs. 28 to 33. 



This handsome species has the branchial bases exactly as in P. splen- 

 dida, that is, they are very small and concealed bj- the collar, somewhat 

 coalesced ventrally, and lack the dorsal la]5pet, ventral membrane and 



