660 Haddon and Shackleton — A Revision of the British Actiniw. 



oesophagus is connected with the filaments in the usual manner. The mesogloea of 

 the mesenteries is well develojied in all our specimens, and is thickened as well as 

 raised into distinct plaitings on that side of each mesentery which bears the longi- 

 tudinal muscle fibres (PI. lx., fig. 9). The parieto-basal muscles are not so well de- 

 veloped as the longitudinal ones; and they extend along each side of the mesenteries, 

 but a short way into the coelenteron ; there is therefore no difficulty in distinguishing 

 between the two sets of muscles ; and the pairing of the mesenteries can be very 

 distinctly seen in this species. The endoderm of the mesenteries is thinner than 

 that of the body-wall. The perfect mesenteries, from the termination of the 

 oesophagus downward, extend far into the coelenteron, which is, in consequence, 

 almost filled up by the mesenteries and their filaments. Transverse sections of 

 P. dixoni, taken just below the oesophagus, present in consequence a very different 

 appearance from those of P. anguicoma taken from the same region. In our 

 specimens of the small variety we find well-marked sinuses in the mesogloea of the 

 mesenteries, extending from the coenenchyme a short distance upward into the 

 coelenteron, disappearing at about the lower termination of the mesenterial 

 filaments. These sinuses are very similar in appearance to the ectodermal sinuses 

 of Z. coppingeri, but we are unable to find in them any connexion with the 

 ectodermal canals of the body-wall, whilst in several places they appear to be 

 distinctly connected with the endoderm. We do not find these sinuses in the 

 mesenteries of any of those specimens of the larger variety of P. dixoni which we 

 have cut. 



Go7iads. — We have found no gonads in our specimens of this species. 



OF UNCEKTAIN POSITION. 

 Zoanthus sulcatus, Gosse. 



Zoanthus sulcatus : 



Gosse, 1860, Brit. Sea Anemones, p. 803, pi. ix., fig. 7 ; pi. xii., fig. 2. Hincks, 1861, Ann. 

 Mag. Nat. Hist. (3), vm., p. 364. 



Qemmaria (?) sulcata : 



Gray, 1867, Proc. Zool. Soc, p. 238. 



Palythoa sulcata : 



Fischer, 1874, Nouv. Arch. Mus. Paris, pp. 236, 239 ; 1874, Comptes rendus, lxxix., p. 1207 

 (trans. Ann. Mag. Nat. Hist. (4), xv., p. 374) ; 1875, Actes Soc. linn. Bordeaux, xxx., p. 8 ; 

 1887, Arch. Zool. exp. gin. (2), v., pp. 435, 437. Jourdan, 1890, Bull. Soc. Zool., xv., p. 175. 

 Polythoa [Taniothoa) sulcata : 



Andres, 1884, Le Attinie, p. 317. Pennington, 1885, Brit. Zooph., p. 183. 



Form. — Column generally cylindrical, but versatile ; upper third of extended 

 column free from sand, and indented with twenty-two longitudinal sulci ; lower 

 portion sparsely incrusted with very fine sand. Disc saucer-shaped. Tentacles, 



