90 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



Numerous specimens, differing in important details from the origi- 

 nal and only known account, are here being referred to this species, with 

 the following added description. The most typical individuals are from 

 the intertidal zones of Pillar Point, San Mateo County. In these, bran- 

 chiae are first present usually from the nineteenth to twenty-first setiger, 

 and continued posteriorly nearly to the end; a short caudal portion of 

 about 10 to 15 segments is abranchiate. Another collection (1241-41) 

 includes 6 specimens in which branchiae are not present until the twenty- 

 third to twenty-eighth segment. 



The dorsum is often marked with dark brown transverse stripes; a 

 bold one crosses the peristomium ; each of the successive segments has 2 

 stripes, one at the anterior end of the segment, the other near the pos- 

 terior end. The latter comes to be an intersegmental dark stripe farther 

 back. The ventrum is pale. The prostomium has a pair of tiny black 

 eyespots between the bases of the paired tentacles and another similar 

 small pair on the front between the bases of the frontal antennae and 

 the outer lateral tentacles. 



Tentacles and ceratophores are rather short, the inner lateral and 

 median are the longest and thickest; the median is sometimes a little 

 shorter and slenderer. Ceratophores each have about 3 short basal rings 

 and a longer distal one. The longest style extends back to about the sev- 

 enth or eighth setiger. The median style is nearly or quite as long, the 

 outer laterals shortest. At the sides the peristomial ring is nearly as long 

 as the first setiger, but shorter at its middorsum. The first setiger is as 

 long as, or a little longer than, the second, with a gradual though slight 

 decrease in length posteriorly. Rarely the anterior end is prolonged so 

 that the first setiger is notably longer, as first shown by Treadwell ( 1922, 

 fig. 181) for the type from Puget Sound. 



The first parapodia are only slightly, if at all, larger than those fol- 

 lowing; a second has the proportions shown in pi. 11, fig. 242. Ventral 

 cirri are cirriform through only 3 setigers (this character was not made 

 known in the original account) ; thereafter they are thick, glandular. By 

 the seventh setiger the dorsal cirrus and postsetal lobe are still long, 

 slender (pi. 11, fig. 246), but smaller than corresponding parts farther 

 forward. Anterior hooded hooks are tridentate, composite (pi. 11, fig. 

 243), the distal tooth usually the largest, but none is sharp or acute as 

 in some species of Nothria. The articulation is a longer or shorter dis- 

 tance from the tip, and clearly visible. The lowest tooth is sometimes 

 very minute, observable only under high magnification. A second para- 

 podium has about 4 of these composite hooks and a few slender, pointed 



