54 
THE VOYAGE OF H.M.S. CHALLENGER. 
less in the mesial line ; and a small upturned spine is seen on each side of the mouth. 
In the form termed “inermis” ( loc . cit. , pi. xlix. figs. 3, 4) the curious external 
marginal teeth are entirely absent. In all other respects, however, it agrees with the 
former, that is to say, in the peculiar form and position of the avicularia, and the habit and 
general characters of the zoarium. They agree also in the circumstance that the 
sides of the zooecium ivithin the frontal membrane are furnished with a few distant, 
minute, sharp-curved spines or spicules, whose function is very obscure. 
The Challenger form agrees in all respects with the second variety, except that it 
presents no vestige of the ascending spine on each upper angle. But on this account 
alone it cannot perhaps be looked upon as more than a variety. 
The marginal zooecia are for the most part void of polypides ; and they are much 
more slender than the inhabited ones. But whether inhabited or not, these zooecia 
always have their external wall furnished with a series of discoid stigmata, probably 
homologous with interzooecial pores or £t Rosettenplatten,” as they are termed, none 
of which, however, appear to exist in the ordinary ooecia. 
(3) Flustra biseriata, n. sp. (PL XVI. fig. 1). 
Character. — Zoarium composed of very narrow, ligulate, bifurcate branches; probably 
several inches high. Zooecia biserial, broadly ovate, truncated below, very convex in 
front. Orifice very wide. 
Habitat. — Station 196, lat. 0° 48' S., long. 126° 58' E., 825 fathoms, hard ground. 
Station 299, lat. 33° 31' S., long. 74° 43' W., 2160 fathoms, blue mud. 
The ligulate di visions or branches are bordered on each side by a continuous chitinous 
tube. 
(4) Flustra membraniporides, n. sp. (PI. XXXII. fig. 7). 
Character. — Zoarium composed of narrow, ligulate, forked lobes. Zooecia pyriform 
in outline, with a large oval aperture occupying more than half the length. Border 
slightly raised. A short marginal spine on each side above ; one or two sessile avicularia, 
with short triangular mandible, on the front of the closed portion of the zooecia near the 
bottom. In the marginal zooecia the avicularium is larger and always single. Ocecium 
small, inconspicuous, with a flattened, triangular or trifid space in front. Surrounded 
with a raised fascia, which is continued across the lower border. 
Habitat. — Station 163b, Port Jackson, 35 fathoms, hard ground. Station 162, off 
East Moncceur Island, Bass Strait, 38 fathoms, sand, shells. 
