gS EXPEDITION ANTARCTIQUE BELGE 



Habitat. — Exp. Antarct. Belge. 



N° 277, Dredge I. Lat. 7i°09' S.- Long. 89 i5' W.; 460 met.; -fo.3 C. 



N° 3y3, Tangles IV. Lat. 71 18' S.- Long. 88° 02' W.; 435 met.; — o.3 C. 



Heteropora claviformis sp. nov. 



PI. VII, figs. Sfl-i/ 



The stud-like zoarium grows from a spreading base, then contracts, forming a wide stalk, 

 which spreads out again, with the upper surface convex. 



The zoœcia open both to the upper and to the latéral surfaces with round apertures, 

 varying in size, and between thèse larger openings there are smaller round ones or cancelli, but 

 there is no sign of any radial arrangement. On the walls between the zoœcia there are minute 

 élévations (8b). The internai pores of the zoœcial tubes are usuallv in transverse lines and 

 deeply sunk, giving the beaded appearance to the wall when broken (8a). 



There is only one perfect spécimen and one broken one, so that it has not been possible 

 to make a complète examination, however a section eut shows the polypides in situ, though 

 histolysis had commenced, but part of the cellular structure of the tentacles and other organs is 

 distinguishable. In thèse sections, near the end of the zoœcial tube, there is a membrane 

 across it, which is what I hâve so often referred to as the « closure ». The parenchym extends 

 up to this, and also on to its external surface, but above this closure the zoœcial tube is 

 filled with mud. The closure before préparation has of course been calcareous. The section 

 being longitudinal the tentacles cannot be counted but there appear to be about twelve. 



This in some particulars is like Domopora, and we know too little about Heteropora to 

 judge how the group may ultimately be divided up. In Domopora stellata Goldf. from Shetland, 

 a few of the terminal zoœcia are closed bv four or rive calcareous rays, reminding us of the 

 rays in Actinosoma ('). Busk mentions rays in H . clavata Goldfuss, but thèse should not be 

 confounded with the closures. 



A spécimen, from the Bancs des Aiguilles (S. Africa), Lat. 34 5y' S.- Long. 19 55' E., 

 75 met., in the Muséum d'histoire naturelle, Paris, has the zoarium exactly the same shape, but 

 smaller, being under 5 mm in diameter, whereas the Antarctic spécimen is about 7mm, the zoœcial 

 walls are thinner giving a more angular shape to the openings, but lower down the zoœcial tube 

 contracts and becomes round. The zoœcia on the side of the zoarium, that is on the upper part 

 of the stalk of the zoarium, hâve a longitudinal direction and the zoœcia are indicated externally 

 by being slightly raised, but on the lower part of the zoarium this is not the case, as the surface 

 is divided into irregular divisions closed by a punctured wall. In the more robust Antarctic 

 spécimen the zoœcial tubes are only indicated for short distances, and openings are seen at 

 intervais on ail parts of the stalk. It seems right to consider the S. African and Antarctic as 

 the same species, although the greater solidity of the second causes certain différent appearances. 



I hâve, in vain, made various efforts to obtain spirit spécimens of Heteropora peltïculata 

 Waters, or other Heteropora from which I could eut sections, as a better knowledge of the 



(1) Young, Geol. Mag., n. s., vol. I, 1874; Waters, Traits. Manch. Gcol. Soc, vol. XIV, pi. I, fig. 1. 



