N. antarcticus has 6 instars. They are; r) prelarva which is passed through within the egg within the female. It is characterized by a pair of 3-segmented palps; 2) larva which is orthotrichous and exhibits several unusual characters, namely, 2 famuli, seta h4 , no circumcapitular furrow and a precocity in the addition of leg setae; 3) protonymph with I pair of genital setae; 4) deutonymph with 3 pairs of gE:nital setae; 5) tritonymph vvith 6 pairs of genital setae and; 6) adult with 8 pairs of genital setae. The male has 7 pairs of eugenital setae and probably produces a spermatophore. The female is ovoviviparous, produces 1 or more eggs (maximum of 4 observed) at a time, and has a vny short ovipositor with 3 pairs of eugenital sEtae. Setae show a concentration on the antiaxial surfaces of the legs, and throughout ontogeny certain leg setae branch. One solenidion is added during development. The femurs of legs I and IV are undivided when they first appear.