In a former paper (1929) it was stated that “regeneration takes place easily at the posterior end of divided syllids, but on cutting the most anterior part, the chitinous tube and massive proventriculus of the pharynx hinder the process of closing the wound and subsequent regeneration fails in most cases”. The minimum length of so-called head pieces, in which regeneration of the tail can be effected, always comprises at least one or two more segments than those constituting the pharyngeal region. This length is internally occupied by a large chamber containing a series of highly specialized organs of ectodermal origin, extending as far as the first appearance of the moniliform intestine in a segmental cavity, which is separated from the previous one by a complete septum.