Nais elinguis is relatively small with the anterior part of the body being brownish in color. It has a simple and rounded prostomium. The pharynx occupies segments II and III. The dorsal bundle of setae contains 2-3 needles and 2-3 hairs, with the needles having a curved tip and finely bifid. The hairs are approximately three times the length of the needles. Ventral setae range from 2 to 5 per bundle, with bifid crotchets. Those on segments II to V are hardly longer, straighter, and thinner than the rest, with the nodulus positioned 1/3 to 1/2 from the distal end. The distal tooth is about twice as long as the proximal one. Pineal setae number between 4-5. The dorsal vessel is located mid-dorsally.