Finally, as regards structure,S the tentacles may retain their primitive hollow nature, or become solid by obliteration of the axial cavity.
The marking out of work was done by fine black lines; and supplemental lines at a fixed distance from the true one were put in to guard against obliteration in course of working (P.T.
Tentacles are hollow; but in some cases the tentacle may become solid by obliteration of its cavity.
The ganglia are crowded at the posterior end of the body as in leeches, and there is much tendency to the obliteration of the coelom as in that group. Pterodrilus and Cirrodrilus bear a few, or circles of, external processes which may be branchiae; Bdellodrilus and Astacobdella have none.
On the other hand there are various offshoots from orthodox Hinduism, the distinguishing feature of which, in their earlier history at least, is the obliteration of caste distinctions and the rejection of the Brahmanical hierarchy.