76 EXPÉDITION ANTARCTIQUE BELGE 



an examination of the British Muséum Challenger spécimen, the operculum was found to 

 hâve a différent shape (see PL V, fig. 5). Busk calls the operculum suborbicular, and figures 

 it as PI. XXIX, fig. 12a, but nothing of the kind is found in Busk's préparation, whereas there 

 are several opercula as given in my figure 5. Some mistake lias been made in the « Challenger 

 Report » which I hâve not fathomed. 



From the Cape Horn Expédition, Dredge, N° 32, Lat. 53° i3' S.- Long. 68°3i' W., 

 97 met., +6°. 6 C, there are spécimens of Cellepora growing from a very small base, which 

 gradually becomes wider, making the colony club-shaped. The growth and appearance is so 

 similar to that of Orthopora compacta, that I h ad no doubt as to its being the same, until I 

 made préparations, and then the operculum showed, that in the aperture there was a wide 

 round sinus, further the mandible is characteristic, having a very narrow, elongate lucida. The 

 lower edge of the aperture frequently appears straight, which is difficult to understand, as 

 the lower edge of the operculum ahvays has the round projection, but the sinus of the aperture 

 must be concealed by calcareous growth in front of it. Sections show that there are only i3 

 to 14 tentacles in the Cellepora under considération, whereas O. compacta has 24. The Cape 

 Horn spécimen will probably be called C. pctiolata nov. 



Habitat. — Exp. Antarct. Belge. 



N° 343, Tangles IV. Lat. 71 18' S.- Long. 88° 02' W. ; 435 met.; — o.3 C. 

 N° 428, Tangles VI. Lat. 71 19' S.- Long. 87 37' W. ; 436 met.; ■ — 0.2 C. 

 N° 6i3, Tangles VIII. Lat. 70° oo' S.- Long. 8o° 48' W. ; 5oo ? met. ; +0.9 C. 



Turritigera stellata Busk 



(PL V, fig. 3a-c; PI. VIII, fig. i3 



Turritigera stellata Busk, Zool. Challenger Exp , vol. X, pt. XXX. p. i3o, pi. XXIV, fig. i ; Waters, op. cit., 

 vol. XXXI. pt. LXXIX, p. 22, pi. I, figs. 22. 25. 



This is evidently one of the most abundant of the Antarctic species, and while most of 

 the spécimens are voung and show but slight branching, there are more fully developed 

 ones, showing that the complète growth is reticulate, which was not the case in the Challenger 

 spécimens examined. 



This species has the peculiarity, pointed out in my «Supplementary Challenger Report», 

 of having the ovicell placed proximally to the oral aperture, instead of distally, as in other 

 Chilostomata, with the exception of Orthopora compacta nov . , and probably two or three species 

 at présent considered to be Cellepora. 



The thin operculum is Schizoporellidan with the muscular attachment some distance from 

 the border of the operculum. Round the aperture there are avicularia on cylindrical processes, 

 but the number varies from three to six, and I do not find any regularity as to the time 

 of appearance or size as mentioned by Busk. The secondary aperture is often closed by a 

 thin dome-shaped calcareous cover, as mentioned in my «Supplementary Report». 



The zoœcial surface has elongate pores, which in alcohol or balsam préparations are 

 seen to be the ends of tubes which run longitudinally as in Hornera, and there are also raised 

 avicularia, with triangular mandibles scattered hère and there. The dorsal surface is quite 

 similar to the anterior and cannot be called rugose. 



