Length near 22 mm.; greatest width exclusive of parapodia, 2.8 mm.; to ends of parapodia, 5 mm.; to ends of setae, 6.8 mm.
Taken as a commensal on a sea-urchin (Metz, July 20, 1911).
Readily distinguished from _L. squamatus_, _coeloris_ and other species recorded from the Pacific coasts of North and South America by the greater length and coarseness of the notopodial setae, these being stout pointed spines often nearly attaining the ends of the neuropodials and thus exceeding the latter in actual length. The notopodials, however, are obviously more slender than the neuropodials; they are much more numerous than the neuropodials and form a dense, subcylindrical, spreading group. The elytra are characterized by bearing over their free portions numerous high and stout, conical, hard or chitinous tubercles which are, however, much less dense than the very different rounded eminences of _squamatus_, these cones often roughened; between these high cones, and over the covered part of the elytra as well, numerous small rounded tubercles or nodules; much more slender and shorter, erect, conical papillæ present on the outer border of at least some of the elytra but no truly ciliate fringe could be detected in the types. The elytra are long, subelliptic in outline, and are arranged either with axis nearly longitudinal or very oblique, the most anterior elytra, however, subcircular. Eyes on each side unusually widely separated, the anterior one low on side, a little ectocaudad of base of anterior process. Anterior processes of prostomium about four-fifths as long as the median ceratophore and much more slender. Lateral tentacles much more slender than the median, and, exclusive of the filamentous tip, falling short of attaining the middle of the style of the latter exclusive of its tip; styles biannulate with black as frequent, the basal process also black. Median tentacle surpassing palpi in length; subapical swelling pronounced, much more so than that of the laterals. Tentacular cirri and notocirri similar in form to the median tentacle. Anal cirri proportionately somewhat shorter than in _squamatus_. Color of venter and parapodia grey; elytra at present grey over a fulvous ground. Setae dark amber to nearly ferruginous, darker than usual in _squamatus_. A paratype has elytra fulvous of dilute ferruginous cast with black mottlings.
