However, the arrangement of paragnaths or fine details of the chaetal blades were not clarified or illustrated.
Grube (1840: 73-74) studied Rathke's material and added some features to the earlier description, especially regarding the chaetal blades and paragnath arrangement on the pharynx, but made no further comment about its identity.
He distinguished these two species by their chaetal blades: short, blunt, rather smooth in N.
This area forms the chaetal sac and chaetae of the mitraria larva.
Our conclusion, based on the location of the chaetal sac, the folding of the archenteron, and the relative locations of the stomodeum, anus, and chaetal sac in the earliest swimming larval stage, is that the blastopore becomes the opening immediately adjacent to the chaetal sac in the larva and thus forms the anus.
4A, 5B), and both the chaetal sac and esophagus have become highly muscular (Fig.
This pattern of chaetal inversion is found in all serpulids, as well as in the related sabellariids and sabellids (Fitzhugh, 1989).
Endocrine substances produced in the prostomium (or in other parts of the anterior end) are well known as signals controlling the timing of asexual reproduction and changes in chaetal morphology in other polychaetes (e.