76 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



The numerous individuals listed above include 2 groups, based on 

 color pattern, although all are believed to be morphologically the same. 

 ( 1 ) In one lot the pigment pattern consists of a transverse row of 4 

 black spots intersegmentally disposed, of which 2 spots are on the dorsum 

 and a pair of similar spots occurs between successive parapodia on the 

 posterior face of segments (pi. 4, fig. 77) ; this pattern extends through 

 16 to 20 segments and thereafter fades gradually to disappearance. This 

 agrees with the pattern described by Monro (1933, p. 76). The follow- 

 ing collections belong to this group: 943-39, 1078-40, 1130-40, 1133-40, 

 1143-40, 1232-41, 1236-41, and 1275-41, and a specimen from Redondo 

 Beach. (2) In the other lot the 2 dorsal spots merge medially to form a 

 transverse bar, and the parapodial spots are larger, diffusing more or less 

 with a similar, though weaker, color over most of the dorsum. It agrees 

 thus with the description by Moore (1911, p. 269). This group includes 

 the following: 767-38, 770-38, 1245-41, 1267-41, 1268-41, 1271-41, 

 1272-41, 1274-41, 1288-41, 1289-41, 1300-41, and 1304-41. 



O. nebulosa is typically a small form, the measurements about as first 

 described. The total length of over 100 segments does not exceed 25 to 

 30 mm. The body is long, slender. The anterior end has prominently 

 outstanding parapodia, but farther back they are not so distinct. Bran- 

 chiae are present from the seventh or eighth setiger, small throughout, 

 never with more than a few (3 or 4) filaments, pinnately arranged on 

 the branchial stem. The prostomium lacks eyespots, or has often an ir- 

 regular spot on either side (pi. 4, fig. 77), or there are sometimes also 

 diffuse pigment spots such as characterize anterior segments. Each of the 

 5 occipital tentacles has a dark spot at the base of the style, where it 

 articulates with the ceratophore. The median and inner lateral tentacles 

 have a purplish- red band a short distance below the tip (pi. 4, fig. 77). 

 The occipital tentacles have short ceratophores, 2 or 3 times as long as 

 broad, with about 4 annul! each ; the longest or inner lateral ones reach 

 back to the sixth or seventh setiger. 



The first few parapodia are larger than those following; a fifth has 

 the proportions shown in pi. 4, fig. 81. Ventral cirri are cirriform through 

 8 segments, transitory through the next 2, and padlike from the eleventh. 

 In anterior segments the postsetal lobe is long, but reduced after the 

 tenth setiger. Anterior parapodia have usually 3 acicula each, the pos- 

 terior parapodia often have only 2 each. Setae of the first 3 setigers have 

 hooded hooks with 6 or 7 articles and a tridentate tip, but those in the 

 first parapodium (pi. 4, figs. 82, 83) are distally prolonged, whereas al- 

 ready in the third the hook is transitory (pi. 4, fig. 79). Anterior para- 



