NO. 3 HARTMAN : POLYCHAETOUS ANNELIDS 317 



(posteriorly incomplete). The prostomium is broadly trilobed in front, 

 the anterior margin truncate but somewhat pushed out of its normal 

 shape. Its median antenna is slender, cirriform, inserted near the middle 

 of the prostomial length, and extends back to the fourth setigerous seg- 

 ment. There are seemingly no eyespots, though there are splashes of pig- 

 ment where they might be expected. 



Branchiae are first present from the fourth setiger, continued posteri- 

 orly to the sixty-fourth, thereafter abruptly absent; they total about 60 

 pairs. They are small at first, increase rapidly in size, come to be thick, 

 coarse, covered over with long cilia except at their tapered distal ends. 

 One from the seventeenth parapodium is shown in pi. 27, fig. 8. 



Parapodial lobes are thick, short, in branchial segments, reduced to 

 low ridges thereafter. Ventral cirri are absent. Dorsal cirri are well 

 developed from the first, but greatly exceeded in length and thickness by 

 the branchiae from the fourth setiger. They come to be increasingly 

 longer so as to extend distally about two thirds as far as the longest 

 setae. Behind the branchial region, dorsal cirri are still long, but slenderer. 



Setae in both rami are long, slender, distally pointed, through at 

 least 133 segments. Lyre setae, hooded hooks, or acicular spines are absent. 

 In anterior branchial segments setae form dense fascicles, thickest in 

 neuropodia, where they are arranged in 3 or 4 vertical ranks through 

 about the thirty-sixth segment, but fewer thereafter. Notosetae resemble 

 neurosetae except that the first are slender and less stiff ; also, they consist 

 largely of finer ones lacking a wing, and some with (pi. 27, fig. 9a) a 

 limbate area. Neurosetae are more sharply geniculate (pi. 27, fig. 9b). 

 Setae in posterior fascicles are entirely fine, silky. 



A. pacifica may be characterized as follows. Branchiae are present 

 from the fourth setiger, number about 60 pairs; parapodial lobes are 

 short, inconspicuous throughout; setae consist of only slender, pointed 

 ones, but the ventral ones in branchial segments are stiffer, more strongly 

 bent than others ; the prostomial antenna is long, cirriform, extends back 

 to the fourth setiger. At least 3 other species belong to the group in which 

 setae are only slender, pointed. They are A. fragtlis and A. nolani (see 

 above), and A. hclgicae (Fauvel, 1936, pp. 29-31) (see Monro, 1939, 

 p. 127). A. pacifica differs from A. fragilis in lacking long, postsetal 

 neuropodial lobes. A. belgicae has only about 13 pairs of branchiae and 

 the prostomial antenna is very short, also branchiae have a slender, 

 terminal papilla. A. nolani is too incompletely known to permit com- 

 parison (see above). 



Holotype.—KYiY no. 70. 



Type locality. — Newport, California, intertidal, in beds of eel grass. 



Distribution. — Southern California. 



