132 PHYLLOCH.ETOPTERUS GRACILIS. 



The tenth segment has at its posterior border dorsally a subulate median papilla, 

 at which the median dorsal band apparently terminates. The base of the papilla is some- 

 what globular, and from this the subulate process extends. 



The eleventh segment has dorsally two branchial processes which have an even 

 margin internally and a slightly enlarged tip, the external border having a crenate 

 process or branch. On the lateral region beneath is a flattened lobe somewhat clavate in 

 outline on its broad side. Ventralwards is the transverse eminence for the hooks, but 

 unfortunately none remain in the specimen. 



Reproduction. — A large example had numerous ripe ova in clusters on its surface in 

 the tube in September. Lo Bianco (1909) met with the pelagic larva of Phyllochxtopterus 

 from June to December at Naples. 



The larva of the Phyllochaetopterus is described and figured by Claparede and 

 Mecznikow (1868) in the mesotrochal stage, with two large and four smaller eye-specks 

 in front, two short tentacles, and a prominent lower lip, followed by a series of bacilli in 

 cells, two median rings of cilia, three other segments with projections, and a long caudal 

 contractile style with two enigmatical organs at the base, which at first sight resemble 

 hernise with bacillary cells. The larva of Telepsavus has a shorter caudal process. 



So far as can be judged from this imperfect example, it is probably the anterior 

 region of P. gracilis, Grube. 



The tube of P. socialis — whether social or solitary — is unknown, so that no oppor- 

 tunity of solving the uncertainty of Claparede in relation to the condition of his at Naples 

 was afforded. The latter forms extensive masses ("prairies"), the tubes being inhabited 

 mostly by one sex, i. e. males, whilst the females are rare, and what is more remark- 

 able is the fact that several occur in each tube, as if budding had taken place, the 

 anterior or upper alone projecting its tentacles from the aperture. Claparede could not 

 satisfy himself as to whether the posterior examples could project from branches of the 

 main tube. In the description of Phyllochdetopterus Glaparedii in the ' Challenger ' 

 Annelids 1 it was stated that an apparent bifurcation of the tube was not uncommon, a few 

 of them showing a series of such regenerations so as to resemble the polypary of a 

 Sertularian. 



In an interesting communication to the Dundee Meeting of the British Association 

 Mr. Potts (1912) gave the life history of a Phyllochsetopterus from the shallow water of 

 Vancouver Island. The long, creeping, horny, narrow, unbranched tubes, which have 

 various openings, are inhabited by several individuals, apparently formed asexually by 

 detaching the posterior region of the body which regenerates the middle and anterior 

 regions. 



Spiochsetopterus. — Tubes apparently of this form have been procured in St. Andrews 

 Bay (E. Mcintosh) dredged in Loch Linnhe in 35 — 37 fathoms ; and thirty miles west of 

 the Blasquet in 110 fathoms (J. Gr. Jeffreys) ; but no example of the annelid has been 

 obtained. 



1 P. 376. 



