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."
While the type of this species includes only the anterior end of the body, its characters seem sufficiently marked for subsequent identification. As in _lampra_, the anterior segments are darkened with purplish brown pigment, especially adjacent to the setigerous papillæ and about the tori, the ventral plates, however, remaining pale. Branchial membrane also pigmented caudally, and the branchiæ transversely banded. Only two eyes on each side are present in the type, a single one each on the second and third radiole from the dorsal end of the series. These eyes are exceptionally large and prominent, much larger than in any of the other species here recorded, embracing practically the entire width of the stalk. The free dorsal edges of the branchial membrane nearly straight, each with only a very slight angulation near its anterior end, not being truly lobate. Nine pairs of radioles. Minor dorsal lobes of collar prominent, produced well forward, curving a little mesad distally, the mesal edge reflected down the dorsal groove as usual.
Width, .75 mm. Length of branchiæ, 2.5 mm.
Differing from the other species here described in having nine setigerous thoracic somites. Anterior somites of thorax darkened above, down the sides on both sides of the tori and also more or less ventrally with purplish brown pigment. Processes or lobes on free edge of branchial membrane above almost of same form as in _P. lampra_ and similarly overlapping. Nineteen pairs of branchial radioles. No eyes. Ventral lobes of collar prolonged, subacute, not overlapping. In the dorsal fasciæ of the ordinary thoracic somites the dorsal setæ are arranged mostly in more or less single, curved, longitudinal series, the clavate ventrals being arranged in two vertical series at right angles to the line of the dorsals. Pennoned setæ of the uncinigerous tori very prominent. Only a few of the most anterior abdominal segments present in type.
Greatest width, 2 mm. Length of branchiæ, 4 mm.
This species is separated from _E. uncinatus_ (Philippi) with some hesitation since specimens of the latter are not at hand for direct comparison. It would seem, however, to be clearly different, to judge from Ehler's figure, in the form of the uncini. These are much broader (i.e., at right angles to the dental line), the base projecting conspicuously but not forming an angulate shoulder as in _E. gracilis_, being nearly evenly and rather broadly rounded. The teeth are mostly seven in number, the end below the last of these set off as usual, rounded. The upper collar setæ coarse, with two teeth or spurs at base of the slender tip, these commonly more or less unequal in size. Branchiæ thirteen pairs. Operculum in general as in _uncinatus_; width of principal expansion 1.25 mm.; the latter even, by narrowing into the stalk, the rim with thirty-eight projecting acute teeth or serrations which are straight or very nearly so, not at all uncate as in uncinatus in which they are also fewer (thirty). Inner crown of eleven spines each tapered evenly to an acute tip and bent in abruptly toward the center above, the proximal portion being erect and ordinarily parallel with the others. No process or series of processes detected within this crown, the base from which these arise being evenly concave on its distal surface and convex on the proximal. Spines of the inner crown dark brown proximally as is the entire basal plate from which they arise, the remaining part of spines light brown. Operculum proper nearly black below teeth on proximal surface of the expansion and on adjacent part of stalk the remaining part of which is white; distal surface of funnel pale. Branchiæ and body in general pale, unmarked or some of the branchiæ with a blackish mark on stalk toward distal end. Thoracic setigerous somites seven. Abdominal segments, ninety.