Isanthidae with well developed pedal disc. Column divisible into scapus and scapulus, on the former sand-grains may adhere (tentaculi [sic] present?). Sphincter strong, mesogloeal. Tentacles up to about 100, the inner longer than the outer ones, their longitudinal muscles ectodermal. Mesenteries divisible into macro- and microcnemes. 12 pairs of mesenteries perfect with filaments and gonads. One mesentery of each pair of the second cycle is, however, weaker than its partner and is devoid of retractor which is present in the other perfect mesenteries. Retractors restricted to almost circumscribed. Microcnemes weak without filaments. Probably more mesenteries distally than proximally.
N. mutsuensis Uchida 1939
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1