_Schistocomus_ gen. nov.
Like Phyllocomus in lacking tentacles and postbranchial spines, in
bearing fifteen pairs of fasciæ of capillary setæ and four pairs of
branchiæ. It differs from that genus in having the branchiæ of two
types, one pair being of the ordinary, smooth, simple, subulate form
and the other three with the edges divided, two pinnately, bearing two
close series of lamellar branches, and one with an essentially single
series of branches in the genotype.
_Genotype_--_S. hiltoni_ sp. nov.
_Schistocomus hiltoni_ sp. nov.
The body has the ordinary general form, being widest near the fifth
setigerous segment from where it narrows continuously to the slender,
pointed cauda. Dorsum convex, venter less so, the latter with a double
median longitudinal furrow in the posterior region. Prostomium
projecting forward as a simple hood with rounded anterior corners and
the median region of anterior edge nearly straight; dorsal surface
in type longitudinally wrinkled. Ventrally the peristomium projects
forward between the sides of the prostomium in a conspicuous lobe or
lower lip which narrows somewhat distad and has the distal margin
convex; surface longitudinally wrinkled. Second somite achaetous. The
third bearing the first fasciæ of simple setæ, the sixth the first
uncini. Of the pinnate branchia one pair occur on the third setigerous
somite and one on the second while the branchiæ with single series of
branches in which the branches are less lamellate, are on the second
(first presetal) somite, the simple branchiæ arising on the first
setigerous somite. The first branchiæ are attached near the middle of
the dorsum, the others laterad close above the parapodia. The first
and especially the second or simple branchiæ extending forward beyond
the anterior edge of the prostomium. Color light fulvous or in part
greyish. Number of segments near fifty-five.
Length, 22 mm.; greatest width, 3 mm.
Type--M. C. Z. 2, 166.
Taken at Laguna Beach, Sept. 15, 1917.
The tube in which the type was found is 35 mm. long. The wall is
thickened by the adhesion of fine particles of sand, fragments of
shell, etc.