BRYOZOA 7 3 



Cellepora horneroides sp. nov. 



(PI. IV, %S. 120-/) 



Zoarium cylindrical, growing from a small solid spreading base, branching in the same 

 plane ; or the branches form more or less cup-like growth, having the zoœcial openings on 

 the outer surface only, and none on the inner. Zoœcia not separated on the surface, which 

 has small linear dépressions, and it may be called fibro-reticulate ; also there are pores scat- 

 tered over the surface, showing a tubular dépression leading to them, besides which there are 

 a very few semicircular avicularia on the surface of the zoœcia. 



The visible, or peristomial aperture, is horse-shoe shaped, contracting towards the 

 proximal end and just below the aperture, or sometimes within it, there is a small avicularium 

 with an obtuse triangular mandible. The avicularium forms a triangular tooth projecting 

 into the aperture, but this tooth is not to be compared with the lyrula of Smittia, being much 

 above the oral aperture. The nearly round oral aperture is closed by an operculum, having 

 muscular attachments a distance from the edge, and the sinus of the aperture is Schizoporel- 

 lidan. Although the peristomial opening has so entirely the appearance of that of Smittia, this 

 is quite différent from the oral aperture, and in fact the operculum is very similar in size, 

 shape and characters to that of Cellepora dichotoma var. attenuata Aider. The ovicell is very 

 slightly raised, and is only distinctly seen when the walls are transparent, as in spirit or 

 balsam préparations. The zoœcia are connected by several long tubes with their neighbours, 

 in this particular resembling a large number of Celleporœ. There are 18-20 tentacles, and 

 in N° 741 there are ovaria attached to the walls of the zoœcia, and embryos in the ovicell. 



This is a very interesting species, through having the zoœcia only on the one surface, 

 which is also the case in a cylindrical form, collected by the Challenger from the West 

 Indies, and named by me Porina proboscidea, when I compared the surface to that of Filisparsa. 



Whether we should for the time being, call this Antarctic form Schizoporella or Cellepora 

 is somewhat doubtful, for it belongs to a group, which has some représentatives among what 

 we now call Cellepora or Osthimosia, and some among Schizoporella, and when a revision of 

 thèse two gênera is made, a genus will hâve to be created, embracing some forms now placed 

 with Osthimosia, and some now with Schizoporella. 



Habitat. — Exp. Antarct. Belge. 



N os 242, g38, Tangles I. Lat. 70 48' S.- Long. gi° 54' W. ; 410 met.; —0.6 C. 

 N os 56i, 567, 570, 571, 5g6, 922, 1012, Tangles VII. Lat. 70 23' S.- Long. 82047' W. ; 

 480 met. ; +0.8 C. 



N° 991, Tangles VIII. Lat. 7o°oo' S.- Long. 8o° 48' W. ; 5oo ? met. ; +0.9 C. 

 N° 741, Tangles IX. Lat. 70° 20' S.- Long. 83° 23' W. ; 459 met. ; +0.8 C. 



Osthimosia signata (Busk) 



(PL VIL fig. 4) 

 Cellepora signata Busk, Zoo] .' Challenger Exp., vol. X. pt. XXX, p. 2o3, pi. XXX, fig. 3 ; pi. XXXVI, ûg. 14. 



Zoarium cylindrical ; zoœcia smooth, flask-shaped, ventricose in the lower part, con- 

 tracted towards the distal end ; peristome raised in a wing-like process, on each side of the 



R 21 



