_Arabella lagunae_ sp. nov.
As compared with _A. attenuata_ Treadwell, this is a smaller species
differing in appearance in being brown of a decided greenish tinge,
excepting on the prostomium and at the caudal end. The prostomium is
less narrowed cephalad, being more broadly rounded across anterior end.
Median eyes not exceeding the lateral in size. Maxillae V represented
by simple small hooks. IV with five teeth of which the most ectal
(upper) is long and slender, the two next much shorter and finer and
the two innermost closer together. III with fine teeth similarly
arranged and formed. Maxillae II nearly symmetrical; the left one with
seven teeth of which the most anterior one is much largest, the right
with an additional small tooth in front of (ectad of) the large one;
neither of the plates extending caudad of the anterior end of the
dental series of I. I with seven or eight well developed teeth; the
carriers very long and slender, black throughout. In the paraphodia the
posterior lobe is well developed, stout and conical, distally somewhat
blunt or rounded, extended ectad or caudoectad and is always shorter
than the setae. Setae all simple, limbate, in a single series of mostly
six in the middle region of the body. Setae with the usual double or
sigmoidal curve over the limbate part, the first bend or geniculation
unusually strong, angular; tip becoming fine and hair-like. Body
tapering caudad, pointed at the posterior end, ending in two blunt
lobes. Number of segments in the type one hundred and ninety-one.
Length, 46 mm.; width, exclusive of parapodia, 2 mm.
Type--M. C. Z. 2, 155.