Genotype—N. hespera sp. nov.
Differs from Thelepus and Athelepus in having the branchiæ branched instead of simple and in having the uncini begin on IV.
Naneva hespera sp. nov.
The prostomium forms a prominent upper lip of which the anterior border is turned upward all along, leaving a deep concavity between it and the upcurving posterior fold along which the tentacles are attached. Because of their curled and tangled condition the precise number of tentacles was not ascertained, but is about twelve on each side; they are long, some when fully extended being 15 mm. in length. No eyes were detected in the type. Peristomium forming a lower lip of but moderate length with straight anterior edge; scarcely twice as long as the second somite below. First branchia on each side attached to second somite just in front and mesad of the first setigerous tubercle. The second branchia attached just caudad of the first on the caudal region of somite III. Both branchiæ very similar, each presenting three principal branches of which the most mesal is largest; ultimate branches numerous, rather short. Capillary setæ beginning on III and continuing to XXVII. The anterior setigerous processes are in the form of vertical plates with straight truncate, distal edge; but in going caudad these become reduced finally to slight tubercles, with the first about equal to half the intervening space and by the seventh equal to this space, while in the abdominal region the opposite series are separated merely by the median furrow. Anterior ventral plates strongly longitudinally furrowed. Capillary setæ narrowly bilimbate, drawn out into a very fine simple tip. Uncini, at least for the most part, in two series both in thoracic and in abdominal region; apparently with mostly three transverse rows of denticles at vertex; beak long, the sinus with parallel sides, opposite side of body evenly curved, not distinctly shouldered. Total number of segments in the type, which is complete, about one hundred and thirty, of which II to XXVII are setigerous. Body rapidly narrowed to the eighteenth segment, but only very gradually thereafter.
Length, near 45 mm.; greatest width, 1.8 mm.
Type—M. C. Z. 2, 169.
Balboa.
SABELLIDÆ
Myxicola monacis sp. nov.
In size and general appearance resembling M. pacifica Johnson, with the type of which it has been compared. From that form the present one may readily be distinguished in having the ventral median process from the first segment drawn out into a slender entire tip instead of being broad and presenting distally two angles or lobes; the process is furrowed longitudinally and the edges are somewhat turned down. Branchiæ twenty-two pairs. Readily distinguished by the form of the abdominal uncini. These have the general form of those of pacifica but as a whole are longer with the body proportionately more slender and its abvertigial end more rounded; the beak is longer and less divergent, distally curving a little back toward the body; the sides of the sinus parallel. The body in the type is somewhat fusiform, being narrowed both ways from the middle but more strongly so caudad. In a paratype the body is scarcely narrowed cephalad. Body somewhat depressed dorsoventrally, less terete than in pacifica. Total number of segments near seventy.