REPORT ON THE POLYZOA. 
121 
sometimes more acuminate and curved, pointing obliquely upwards and outwards (fig. 2b). 
No dorsal avicularia. 
Habitat. — Off Honoruru, Sandwich Islands, 20 to 40 fathoms. 
The specimens of this well-marked species in the Challenger Collection are very 
numerous, but unfortunately only in fragments of various sizes, some of which measure 
2 to 3 inches across. The specimen figured, of the natural size, is one that has been 
long in my collection. Mr. Hincks appears to have contemplated giving the same 
name to a variety of Retepora monilifera d 
(15) Retepora cavernosa, n. sp. (PI. XXVI. fig. 8). 
Character. — Zoarium intricately contorted, the folds forming numerous anastomoses, 
so as to constitute a collection of tubular cavities about 0 //- 25 in diameter. Fenestras 
very minute, circular or suboval, uniform. Zooecia with very thick 
walls, deeply immersed and irregularly disposed. Orifice immersed, 
with a thick tumid peristome. Labial fissure nearly median, very short, 
forming, in fact, merely a small labial pore, the peristome being 
thickened on each side of it. Outline of zooecia very obscure, but 
apparently rhomboidal. Ooecia tumid, convex in front, with a wide, 
trifoliate, perforated stigma ; the anterior border of its orifice straight 
(fig. 8 d). Anterior avicularia very rare, of an oval form, slightly 
elevated ; mandible short, spear-shaped, acute, pointing obliquely downwards. No dorsal 
or fenestral avicularia. 
Habitat. — Station 148, lat. 46° 47' S., long. 51° 37 ; E., 210 to 500 fathoms, hard 
ground, gravel, shells. 
As this form is represented in the collection by only one or two fragmentary 
specimens, the habit and dimensions of the zoarium cannot be determined, but it is 
probable that the latter are considerable. In its intricately contorted growth Retepora 
cavernosa resembles Retepora columnifera, but in that species the alveoli formed by the 
anastomoses of the folds are for the most part infundibuliform, whilst in Retepora 
cavernosa they may be more correctly described as tubular. 
(16) Retepora tubulata, n. sp. (PI. XXVIII. fig. 2). 
Character. — Zoarium springing from a narrow base, without a distinct peduncle ; 
immediately becoming tubular and continuing to grow by throwing out short tubular 
alveoli, each of which soon expands into a wide infundibuliform dilatation. Fenestrm 
1 Ann. Nat. Hist., ser. 5, vol. i. p. 362, 1878. 
(ZOOL. CHALL. EXP. — PART XXX. — 1884.) Gg 1G 
Fig. 31 . — Retepora 
cavernosa 
