Adult females have been recorded up to 800 mm long, although the few males known do not exceed 40 mm. The mouth is small and triangular and is surrounded by a quadrangular, sclerotized plate.
Lips are absent.
Cephalic papillae are arranged in an outer circle of four double papillae at about the same level as the amphids and an inner circle of two double papillae, which are peculiar in that they are dorsal and ventral. The esophagus has a large glandular portion that protrudes and lies alongside the thin muscular portion. The gravid uterus has an anterior and a posterior branch, each of which is filled with hundred of thousands of embryos. The intestine becomes squashed and nonfunctional as a result of the pressure of the uterus. Spicules of the male are unequal and 490 to 730 um long.