Body rather stout for a syllid, more as in Hesionidae; broadest and deepest anteriorly, continuously narrowing caudal to the pointed posterior end. The color of the dorsum is blackish, with pale transverse lines in the intersegmental furrows and bisecting each somite which under the lens thus appears double. Parapodia and cirri typically pale fulvous and the venter either similar or approaching the dorsum in color. Prostomium very short, sunk in the first body ring and almost completely overlapped by the quadrate flap from the latter, this flap extending over the bases of the tentacles in the type. Palpi stout, presenting two main lobes fused to their apices or nearly so, and on each of these an ectodistal lobe projecting ventrocephalad, these distal lobes wholly free from each other. Tentacles appearing nearly smooth; tapered; the median exceeding the lateral in length. Eyes large; in type orange colored; the two on each side contiguous or nearly so; posterior ones nearer together, each beneath edge of the quadrate peristomial flap, while the anterior ones are in line with base of median tentacle. Tentacular cirri of same form as tentacles but longer. Neurocirri thick, short, distally rounded. Natocirri long, filiform, tapering distad, weakly ringed; showing a tendency to alternate in height on the sides of the body, the first being notably farther distad than the second, the third than the second and fourth, etc. Setae numerous; the appendage short, falcate, with tip simple, but a slender tooth near middle of curved edge. Segments short, crowded, near one hundred in number. Length of type, 21 mm.; greatest width, 2.2 mm. Type--M. C. Z. 2, 149. Taken in August, 1914. _Hesperalia nans_ sp. nov.