82 EXPEDITION ANTARCTIQUE BELGE 



R. protecta is allied to R. porcellana MacG., but the zoarium of protecta is less solid, with 

 smaller fenestrœ, and there are no labial avicularia. 



Habitat. — Exp. Antarct. Belge. 



N° 242, Tangles I. Lat. 70048' S.- Long. 91° 54' W.; 410 met.; +0.6 C. 



N° 3og, Tangles II. Lat. 71 14' S.- Long. 89° 14' W.; 460 met.; 4-0.3 C. (var. crassa). 



N° 33g, Tangles IV. Lat. 71 18' S.- Long. 88° 02' W.; 435 met.; — o.3 C. 



N os 620, 683, ggi, Tangles VIII. Lat. 70 00' S.- Long. 8o u 48' W.; 5oo?met.; 4-0.9 C. 



Retepora frigida sp. nov. 



PI. VI, figs. 4a-/ 



Zoarium large, as judged from the fragmentarv spécimens, which are only slightly 

 curved, thus indicating a large colony ; one flat pièce is 25 mm X i5 mm . Fenestrse larger than 

 those of R. protecta sp. nov. being about 2.4™™ to 3.6 mm long, and about o.8 mm to i.6 mm wide. 



Zoœcia indistinctly separated, surface smooth, with elliptical avicularia to some of the 

 zoœcia, and an occasional gigantic, raised avicularium, having a triangular mandible with 

 elongate beak. The oral aperture, as shown by the operculum, is nearly straight below, and 

 the distal edge is more than a half circle. The labial pore is to one side, and is formed by 

 calcareous growth on each side meeting over it ; the plate at the proximal edge of the aperture 

 is below the surface, and is notched, whereas in R. protecta it is erect ; at each side there is a 

 jointed spine. 



The ovicell is almost concealed, onlv showing as slightly elevated above the aperture, 

 and is entire, though in one or two cases there is a faint mark, reminding us of the ovicellular 

 slit of R. celhdosa &c. The dorsal surface is smooth, divided irregularly by vibices, and has 

 numerous elliptical avicularia. There are about 14 tentacles, the glands are long, and there 

 are testes with spermatozoa. 



The structure is very similar to that of R. protecta nov. in several points, but the fenestrse 

 are larger, the surface is smooth, and instead of having a raised plate in front of the aperture, 

 it is well within the aperture, and there are large, raised, triangular avicularia. There is also 

 considérable similarity to R. laevigata nov., but the opercula are quite différent. 



Habitat. — Exp. Antarct. Belge. 



N os 33g, 345, Tangles IV. Lat. 71 18' S.- Long. 88° 02' W.; 435 met.; — o.3 C. 



Retepora laevigata sp. nov. 



(PL VI, figs. 5a-d 



Zoarium cup-shaped, fenestrse large, branches narrow. Zoœcia smooth, indistinct, 

 without divisional lines, distal end not raised, peristomial aperture with wide sinus within 

 which are seen the two teeth meeting and forming a pore, on the surface there are scattered 

 small semicircular avicularia, but often none are to be found upon a branch. There are six 

 spines in the younger zoœcia, but thev are not found in the older zoœcia. The ovicells are 

 not raised, and while there is a mark down the front I do not think it is a fissure. 



On the dorsal surface there are few and very délicate vibices, on some branches none 



