REPORT ON CORALS — HYDROCORALLIN^E. 95 



coenosteum in the male (?) Gastrozooids cylindrical, with four club-shaped tentacles and 

 four basal canals. Dactylozooids entirely retracted. Gonophores in the female solitary 

 in the gonangia. The free margin of the cup-shaped spadix becomes converted into a 

 ramified fringe, embracing the embryo as development proceeds. Planula as in 

 Pliobothrus. Structure of male stocks unknown. 



4. Distichojiora, Lamarck. 



Coenosteum branching flabelliform, with branches usually flattened in the plane of 

 the flabellum ; composed of very compact ccenenchym. Pores in most species confined 

 to narrow lines or rows running along the exact centres or edges of the sides of the 

 branches, usually absent on their faces, except as occasional abnormalities or rudimentary 

 branchlets budding in a direction out of the plane of the flabellum. The lines of 

 pores composed of three rows, a central row of larger gastropores with circular or 

 oval mouths ; and a row on each side of this of smaller dactylopores, sometimes 

 very minute, sometimes prominent and tubular, often slit-like in aperture, the length of 

 the slit being directed at right angles to the line of the row. Pores very deep, prolonged 

 in curved lines side by side in the plane of the flabellum, inwards and downwards towards 

 the bases of the branches ; forming thus throughout the flabellum a thin continuous 

 tract of fragile tubulate tissue, in which the successively-developed curved pore-tubes stand 

 out fanwise, separating from one another the compact masses of ccenenchym forming 

 the opposite faces of the branches. The branches may, therefore, be readily split into 

 two halves along this tubular tract. Older gastropores with immensely long filiform 

 styles ; those in the younger gastropores much shorter. Dactylopores devoid of styles. 

 Ampullae sometimes on one, sometimes on both faces of the flabellum, prominent in the 

 females and often forming confluent masses ; sunk beneath the surface of the coenosteum 

 in the males and invisible exteriorly. Soft structures closely like those of Errina. 

 Dactylozooids with very long retractor muscular slips ; gastropores with four clavate 

 tentacles. Gonangia as in Errina in the females ; in the males, containing four or 

 five ovoid masses of spermatozoa. 1 



5. Labiopora, Moseley 2 (PL II. fig. 5). 



(Type specimen in British Museum ; mistaken by Gray for a Bryozoon, and described 

 by him as Porella antarctica), (Proc. Zool. Soc, 1872, p. 746, pi. lxiv. fig. 4). — Coenosteum 

 minutely reticulate in texture, composed of a few rounded branches with tapering- 

 extremities. The entire surface covered with nariform projections, with elongate cavities, 

 which are arranged in rows along the lengths of the branches, often disposed with great 

 regularity for long stretches. The projections of very uniform shape, and rising from the 



1 Some specimens dredged off the Tristan da Cunha group are probably males, having the ampulla? small, and 

 buried in the substance of the ccenosteum. 



s Prelim. Report, Phil. Trans. Roy. Soc, 1878, part 2, p. 476. 



