Description (from Thorne, 1939)
    Body assuming the form of an open letter C, especially when killed by gradual heat.  Transverse striae indistinct.  Cuticle with a distinct outer layer which is especially conspicuous on the tail.  Amphid apertures half as wide as head.  Lateral cords one-seventh as wide as body.  Tooth very slender, three-fourths as long as the head width and hollow only one-third its length.  Second and third sections of pharynx obscure.  Esophagus enlarged by gradual expansion slightly anterior to middle, the enlarged portion frequently exhibiting a hyaline, columnar structure, especially in the posterior section.  Ovaries reflexed four-fifths the distance back to the vulva.  Males unknown from among several thousand specimens observed at all times of the year.
    Habitat: The most prevalent nygolaim of the Western United States.  Collected from cultivated valley soils of Utah, Idaho, California, Colorado, and Oregon.