1923] NATURAL SCIENCES OF PHILADELPHIA 247 



watch spring. Barbs very long, slender and delicate, most of 

 them of a length equalling or exceeding the body width, increasing 

 in length distally. Oral membranes and tentacles not clearly seen. 



Collar high and ample, reaching somewhat beyond the branchio- 

 phores to the bases of the radioles, which it loosely envelops; its 

 margin regular, entire, smooth, of even height, the dorsal angles 

 rounded and the dorsal borders refiexed to the peristomium and 

 bounding the fecal groove as a pair- of thin parallel folds separated 

 from the collar proper by deep incisions. 



Thoracic segments nine (8 setigerous), short, about one-fourth 

 as long as wide, simple, uniannulate and separated by distinct 

 furrows. Fecal groove very oliscure except in the collar region. 

 No distinct ventral plates. Abdominal segments 17 or 18, strongly 

 marked by deep furrows, uniannulate; as the body tapers becoming 

 relatively longer toward the caudal end which is rather acutely 

 pointed. Fecal groove well developed throughout the abdominal 

 region, but there appear to be no true glandular ventral plates. 

 Pygidium small, pointed, with no caudal style but only a small 

 dorsal tubercle above the slit-like anus which is directed o])li(iuely 

 caudo-ventrad. 



Collar setae in rather prominent linear fascicles; remaining tho- 

 racic fascicles more compact. Thoracic tori narrow, transverse 

 ridges below and slightly behind the setae tufts, the largest not 

 exceeding one-twelfth the circumference of the segment, and bearing 

 a short series of only about fifteen crochets. Abdominal setae tufts 

 ventral and very small, the dorsal tori shorter and less elevated 

 than the thoracic, with the number of uncini varying from al)out 

 a dozen anteriorly to three or four at the caudal end. 



All setse and uncini colorless. Collar setae and dorsal setae on 

 remaining thoracic segments very narrowly lanceolate, evenly 

 bilimbate, with the borders strongly striated. Ventral thoracic 

 setae with broadly obovate expanded ends having strongly striated 

 borders and a stout mucron. A})dominal setae very few in each 

 fascicle, like the dorsalmost thoracic setae but more slender and 

 becoming gradually more elongated until at the caudal end they 

 are practically strictly smooth capillaries without limbi. Thoracic 

 uncini of crochet form with slender, curved, striated stem about 

 the diameter of dorsal setae and with small l)eaked head with 

 finely striated crest toothed on the vertex only. Alxlominal uncini 

 of the terebellid type with short (juadrate Ijase, deep siiuis and long, 

 slender beak surmounted l)y a small crest. 



Tubes delicate, closely fitting the worms and so far as preserved 

 not exceeding them in length, soft and membranous, the basal 

 half without covering, thin and transparent, the distal half in- 

 creasingly coated with a soft, gray, flocculent silt in which are 

 scattered minute fragments of shell, etc. 



