_Natomastus angulatus_ sp. nov.
In comparison with <i>N. tenuis</i> Moore, known from San Diego, this species
differs in the form of the thorax, which is strongly angulate instead
of terete the sides and venter being flat and the dorsum usually but
little convex, so that the cross-section is nearly quadrate; also in
having the segments and their subdivisions sharply separated with
the posterior subsegment in each case much shorter than the anterior
instead of equal to it. In the type the posterior thoracic somites
are twice or more as long as wide, but in some paratypes the relative
length is much less. Thorax narrowed caudad. The abdomen in its
anterior part obviously thicker than the thorax in its widest part.
The prostomium characteristic, showing two distinct regions, a broad
posterior one with convex, anteriorly converging sides and a narrower,
subconical, palpoidal terminal part sharply set off from the basal.
Segments of abdomen irregularly multiannulate, sulci deep and surface
usually appearing strongly rugose and uneven.
Length near 160 mm.; greatest width of abdomen, 1.4 mm.
Type--M. C. Z. 2, 164.
Taken in sand and in growths of eel grass. The color is noted as
reddish in life, as usual in the family.