III.—Regeneration and reproduction of the syllid procerastea

Abstract

The family Syllidae is divided into four sub-families, of which the sub-family Autolytea is characterised by the absence of ventral cirri on the setigerous segments. The genus Procerastea was established by Langerhans (1884) and is defined as an Autolytea in which the parent stock (souche) has dorsal cirri on the first setigerous segment only. Behind the first setigerous segment the parapodia consist simply of small lobes (neuropodia) from which a single bundle of setæ projects. Langerhans described under the name Procerastea nematodes a species he found in Madeira, which he states has a short pharynx provided with six indistinct teeth. Malaquin (1891, p. 175; 1893, p. 81) describes a second species of the genus found by him at Boulogne, characterised by a pharynx armed with a circle of 20 to 22 teeth and possessing a distinct loop, similar to that generally found in the genus Autolytus. Malaquin named his species Procerastea Halleziana and says (1893, p. 81) that the worm lives in the interior of the test of large Ascidians (Ciona) on hydroids and bryozoa. Some specimens belonging to Malaquin’s species were found at Plymouth in 1914 and recorded in the ‘Journal of the Marine Biological Association’ (Allen, 1915). These specimens were obtained from amongst Ascidians growing on a raft moored in Cawsand Bay.