NO. 4 HARTMAN : POLYCHAETOUS ANNELIDS 423 



small but by the fourth they are much larger and have the characteristic 

 fan-shaped fascicles as those farther back. Lateral organs increase in size 

 to the middle of the thoracic region but they tend to be somewhat con- 

 cealed by the shallow lateral groove and by a superior raised portion of 

 the neuropodia; they are located between the parts of the parapodia but 

 nearer the dorsal branch. Nephridial pores have not been distinguished in 

 any part of the thorax or abdomen but whether they are present during a 

 stage in the ontogeny of this species cannot be determined from the single 

 collection available. The last 3 or 4 segments of the thorax are longer 

 and slenderer than those farther in front; the length is nearly twice the 

 width at its greatest development; the setal fascicles are at the anterior 

 end of the posterior half but the last thoracic segment is again shorter 

 and its parapodia are located near the posterior end of the segment. 



Abdominal segments are noticeably shorter and wider than the pos- 

 teriormost thoracic segment. A sharp, narrow groove extends length- 

 wise along the middorsum. Parapodial ridges are located on the pos- 

 terior third and move gradually farther back toward the segmental 

 groove. By the eighth or ninth segment there is an anterior, inflated 

 portion and a constricted posterior third on which are located the un- 

 cinigerous tori. When individuals are strongly contracted through pres- 

 ervation, the inflated region may have the appearance of being strongly 

 wrinkled in a transverse direction. 



Notopodial ridges are shorter than the neuropodial ones and dorsal in 

 position but the 2 of a pair are separated by a narrow space and by the 

 narrow longitudinal furrow. Neuropodial ridges are ventrolateral in 

 position and the 2 of a pair are separated by a broad space that extends 

 nearly across the width of the body. Neuropodial uncini are in longer 

 rows, bounded by a raised membrane that is prolonged dorsally so as to 

 extend nearly to the notopodium but the 2 are separated by a depression 

 in which the papillar lateral organ is located (pi. 49, fig. 1). This 

 arrangement continues posteriorly through at least 60 abdominal seg- 

 ments. No branchiae or nephridial pores have been distinguished. 



The hooded hooks of the abdomen have a shaft with distinct but short 

 shoulder and neck regions. The hood is short and extends distally only 

 slightly beyond the crest. The margin of the aperture appears smooth 

 but may be vaguely dentate. The beak terminates in a long fang sur- 

 mounted by a crest with 5 teeth arranged in 2 rows in which 3 teeth below 

 alternate with 2 above (pi. 49, fig. 5). The base of the shaft is only 

 slightly curved backward. 



