Somewhat resembling P. elongata (Johnson), which also occurs in this region, but differing in having the dorsum pigmented throughout, being black or slaty with pale lines between the segments and dividing each of the latter transversely excepting across the middorsal region. The pigmentation may sometimes be very dilute. In technical details readily distinguished from that species, e. g., in the different form of the appendage of the setae, this being obviously more elongate and erect and proportionately more slender. Two or more dorsal setae differ in having shorter, more strongly curved appendages which are wholly smooth on the concave edge instead of being pubinate to beyond middle as in the others. Prostomium rather short and broad. Palpi thick the ectal lobe small as compared with the principal or mesal one; united only at base. Eyes small, transversely elongate and often curved, the two on each side close together and sometimes almost fused, with the posterior one well mesad of but only a little caudad of the anterior one. Median tentacle situated midway between the two eye groups in a longitudinal furrow dividing prostomium; composed of eighteen to twenty-three short articles. Each paired tentacle at corner of prostomium in front of eye-group of corresponding side; similar in form and size to the median tentacle. Lower tentacular cirrus about equalling a tentacle in length, the dorsal longer, both of similar form. First segment extending forward in a rounded or subtriangular lobe or flap at middle above. The notocirri attached above bases of parapodia as usual; long, composed of numerous short segments; much longer than the tentacles, each average one when laid back along body ordinarily passing over three or three and a half segments. Neurocirri short, stout, fusiform. Body slender, narrowed moderately at the ends, elsewhere of nearly uniform width. Type composed of seventy-three segments.
Length, near 20 mm.
Type—M. C. Z. 2, 148.
Littoral zone.
Pionosyllis lucida sp. nov.
Readily differentiated from P. elongata, which it resembles in its pale, translucent appearance, in having the distal appendage of setae more typical, being of a decidedly more elongate and erect form which also differs from that of pigmentata. From the latter differing conspicuously in appearance in lacking all dark pigment. Notocirri tapering distad, with apical region slender and pointed; long, exceeding the width of the body and consisting of up to forty-five articles. Differing from pigmentata in the form of the neurocirri which are more uniform in diameter, subcylindric rather than fusiform; normally extending more or less beyond the tip of the parapodium. Prostomium short. Eyes reddish; those of first pair larger than the second; second eye on each side almost directly mesad of the first but only a little caudad of it. The median tentacle farther forward than in pigmentata, well in front of the eyes, its anterior edge being nearly in line with the caudal margins of the paired tentacles; composed of twenty-eight or more short articles. Paired tentacles much shorter and also more slender; composed of about twenty articles. Palpi fused at base as usual; narrower distally than in pigmentata. The types are incomplete caudally; but the body is evidently slender. One specimen 8 mm. long consists of forty-three segments; and a second, somewhat thicker one, of nearly the same length consists of thirty-seven. The width is near 1 mm.
Type—M. C. Z. 2, 180.
Hesperalia gen. nov.
Palpi thick, fused at base only to middle of length. Pharynx straight. Proboscis unarmed (?). Tentacles three, attenuated, more or less obviously jointed. Eyes two pairs; large. Tentacular cirri two pairs. Parapodia uniramous with setae all compound, or in the epitokous phase with long simple natatory setae in notopodia of middle region of body. Appendage of compound setate short, bidentate. Neurocirri present, thick, rounded. Notocirri on side of body above parapodia; filiform; more or less segmented. A large quadrate membrane or flap projecting from anterior edge of peristomium forward over caudal region of prostomium.
Genotype.—H. californiensis sp. nov.