Hatschek (1888) treated the Entoprocta as a division of his group Scolecida, characterized by the possession of a primary body-cavity and of protonephridia; while he placed the Ectoprocta, with the Phoronida and Brachiopoda, in a distinct group, the Tentaculata.
H.) (After Hatschek.) FIG.
212; (2) Hatschek, Lehrbuch der Zoologie (1891), pp. 316-326; (3) A.
HAPLODRILI (so called by Lankester), often called Archiannelida (Hatschek), the name provisionally given to a number of FIG.
The development of Polygordius alone is well known, having been studied by Hatschek, Fraipont and others.