NO. 3 HARTMAN : ORBINIIDAE, APISTOBRANCHIDAE, PARAONIDAE 283 



Thoracic parapodia are inconspicuous in anterior segments; both 

 notopodia and neuropodia have small papillar lobes located about mid- 

 way along the postsetal ridge. Farther back the notopodial lobe is longer 

 and triangular (fig. 1), the neuropodium has a longer ridge with the 

 upper part prolonged. Notopodia have only pointed setae accompanied 

 by slender embedded acicula. Neuropodia have thicker fascicles of yellow, 

 distally pointed setae and fewer uncini in palisaded series. They are so 

 arranged that the anterior one to several rows are pointed setae, followed 

 by one to three rows of uncini with 8 to 15 in a row at maximum de- 

 velopment or the uncini may be absent from the upper part of the 

 fascicle; the posteriormost row consists of pointed setae only. The 

 uncini are distally curved ; each has 6 to 8 transverse ridges along its 

 outer side (figs. 6, 7) ; a translucent hyaline hood ensheaths the distal 

 part (lacking from worn uncini). The pointed setae are spinous beyond 

 the shaft, with the spines in numerous transverse rows (fig. 3) and 

 extending nearly around the seta (fig. 4). Furcate setae (fig. 5) are 

 present in abdominal notopodia; the shaft is spinous and the distal tines 

 are unequally long. 



In the abdomen the notopodial postsetal lobe is long and erect ; the 

 neuropodium consists of a longer supra-acicular lobe and a shorter sub- 

 acicular one (fig. 2). Dorsal ciliated mounds are visible from segments 

 11 to 13 and continue on more posterior segments; the pair are widely 

 separated at first but rapidly approach middorsally, so that by segment 

 20 or 21 they are proximal to each other. Statocysts are present on 

 branchial segments in front of the branchial base (fig. 2), at least from 

 the second or third branchial segment. The pygidium has a pair of very 

 long, cirriform processes inserted dorsolaterally. 



Scoloplos acmeceps is sometimes associated with Haploscoloplos 

 elongatus. They are distinguishable grossly in that the first has a greatly 

 depressed thorax, the second a slightly depressed one; the first has 

 thoracic uncini, the second lacks them ; the first has more spinous noto- 

 setae than the second. 



Distribution. — Scoloplos acmeceps is known from Alaska south to 

 western Mexico in littoral zones ; it is associated especially with hold- 

 fasts of algae and grasses, in littoral zones. 



Scoloplos treadwelli Eisig, 1914 



Aricia cirrata Treadwell, 1901, pp. 201-202, figs. 54-57. 

 Scoloplos treadwelli Eisig, 1914, pp. 405-407; Augener, 1927d, p. 69. 

 Collection.— 2597-54 (1). 



