124 PROCEEDINGS OF THE NATIONAL MUSEUM you. 92 
segments, but occasionally a single, slender, limbate seta is present 
near the superiormost part of the fascicle. A twenty-first neuropo- 
dium contains 5 dark acicula, 10 inferior pointed setae, 6 simple 
hooded hooks, 10 superior pointed setae; its notopodium is provided 
with an embedded fascicle of acicula. A far posterior parapodium 
may contain three black acicula and about five hooded hooks, usually 
no limbate seta. 
L. zonata is common in the intertidal zones of the northeast Pacific, 
to considerable depths. The National collections contain specimens 
from the Behm Canal, Alaska (Albatross stations), including depths 
of 14 to 256 fathoms. 
Genus ARABELLA Grube 
ARABELLA IRICOLOR (Montagu) 
Nereis iricolor Montacu, 1804, p. 83. 
Lumobriconereis tenuis VERRILL, 1873, p. 594 (part) (U.S.N.M. No. 13883; Vine- 
yard Sound, in 12 fathoms). 
A collection labeled “Cotypes” includes numerous small, slender 
individuals of Arabella tricolor (Montagu). The prostomium is sub- 
globular, with four eye spots in a transverse row; parapodia are 
provided with only pointed, limbate setae, hence Arabella. The 
proboscideal armature is typical of A. zricolor. 
In the original description the prostomium was said to lack eyes, 
also, at the sixteenth segment “recurved spatulate setae, with two 
to three hook-like denticles at the end [hooded hooks?], while two or 
three lanceolate ones remain.” It seems, therefore, that these so- 
called “Cotypes” are not the same as that on which the first descrip- 
tion was based. A holotype has not been found. 
ARABELLA IRIDESCENS Treadwell 
Figure 13, d 
Arabella iridescens TREADWELL, 1906, p. 1171 (U.S.N.M. No. 5216; Pailolo Chan- 
nel, between Molokai and Maui, in 12 fathoms). 
There is only a single fragment, with much of the maxillary ap- 
paratus missing and most of the setae broken away flush with the 
body wall. The prostomium is elongate, depressed, triangular, with- 
out eye spots or other color markings; it lacks a median sulcus but 
has a depression in the middle on both dorsal and ventral sides. 
The proboscideal region has been largely dissected out; mandibles 
are lacking but some maxillary parts (fig. 13, d) remain. The 
carriers are very long, slender, with a short, rounded, ventral, un- 
paired piece that terminates in a ragged edge; the whole only slightly 
chitinized. Maxilla I on the right side is roughly triangular in 
outline, with 8 (or 9) teeth on the cutting edge. Maxillae IT and 
III (fused) have 16 teeth; maxilla IV is presumably lost from this 
