The type of this species is a small individual which, as preserved, appears of a uniform dusky color throughout. Branchial radioles fourteen or fifteen pairs; in a single series, the membrane not being coiled. No eye spots. Collar with ventral lobes proportionately long and acute, the dorsal lobes small and approximate. Notopodial setæ of usual two types; few. Uncini with beak divergent, nearly horizontal, the "neck" short and the edge of body below bulging much as in _Paralaonome japonica_. Body furrowed along each side just above notopodia excepting anteriorly. Ventral plates sharply limited, elevated; all of abdominal plates bisected by the median longitudinal sulcus excepting the first one, which is entire. Total number of somites, fifty-six, of which eight are thoracic. Length without branchiæ, 12 mm.; with branchiæ, near 15 mm. Type--M. C. Z. 2, 175. Taken among tufted algæ, June 25, 1911 (C. F. Baker). _Pseudopotamilla lampra_ sp. nov. In this form the collar membrane is crossed by a series of longitudinal dark stripes, one in line with each radiole, as in _Potamilla colorata_, these narrowing caudad. Branchiæ sometimes mostly dark with light transverse bands. Anterior thoracic segments darkly pigmented both above and below, and also along both sides of tori, and most setigerous papillæ and tori of succeeding regions of body also surrounded in some degree with a pigmented area. Branchial membrane with free dorsal edges produced into two lobes on each side, the two of each pair overlapping, the posterior lobe rounded, the anterior angular with its caudal margin transverse and the other long and oblique. Radioles nineteen pairs, several of these at dorsomesal end of series much reduced. Eyes conspicuous but few, only one, or occasionally two, on a radiole and some radioles wholly lacking them. This species has only seven setigerous thoracic somites. Total number of segments, near ninety-four. Length, about 28 mm.; with branchiæ, 33 mm. A note states that this form is pinkish in life. A paratype was taken "in a large white sponge." Type--M. C. Z. 2, 176. _Pseudopotamilla macrops_ sp. nov.