316 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



throughout the length of the body. In anterior and branchial regions, 

 neuropodia have a characteristic postsetal lobe (called ventral cirrus by 

 Webster) which reaches its maximum development at about the thirty- 

 second parapodium (pi. 27, fig. 5), thereafter gradually diminishes and 

 is absent some distance behind the branchial region. Ventral cirri are 

 absent, as typical of the genus. The prostomium is anteriorly rounded, 

 has 2 tiny black eyespots in front, a pair of nuchal organs near its posterior 

 margin, and a cirriform median antenna (pi. 27, fig. 4). 



A. quadrilohata Webster and Benedict (1887, p. 739) from Eastport, 

 Maine, w^as originally described from individuals only 5 to 6 mm long, 

 but "with large irregularly polygonal eggs, clear white, with distinct 

 nucleus," hence supposedly mature. Branchiae were described as first 

 present from the fourth, continued through 9 segments. A unique feature, 

 shown in the figures, but not discussed in the text, is the presence of a 

 setal lobe in neuropodia, through the branchial region and continued 

 some distance in the postbranchial region, just as in //. jragilis. Similarly, 

 setae are entirely slender, pointed. A. quadrilohata resembles A. jragilis 

 closely except in its veiy small size and reduced number of branchiae, 

 both of which may have no specific significance ; their identity is suggested. 



Aricidea nolani Webster and Benedict (1887, p. 740), also from 

 Eastport, Maine, was described from specimens measuring only about 

 7 mm long. Branchiae are present from the fourth setiger, continued 

 through 13 to 20 segments. It differs from A. jragilis especially in lack- 

 ing the postsetal neuropodial lobe (called ventral cirrus by Webster and 

 Benedict) in the branchial region. Although this species has been question- 

 ably referred to A. jragilis (Fauvel, 1936, p. 65), it may be distinct in 

 this respect. 



A. jragilis inhabits burrows in fine sandy shoals, at low water line, 

 often associated with species of Scoloplos^ from which it is most readily 

 distinguished in being notably slenderer and smaller. 



Distribution. — Eastern America, from New England, south to North 

 Carolina; intertidal. 



Aricidea pacifica, new species 

 Plate 27, Figs, 8, 9 



Collection.— 1441-41 (1). 



The body is broad, depressed in the anterior region, less flattened in 

 the postbranchial portion. Anterior end, through 50 segments, is more or 

 less tightly coiled up, the rest of the body irregularly twisted, the total 

 length difficult to estimate, but approximately 31 mm for 133 segments 



