REPORT ON THE POLYZOA. 
97 
and probably also below, though the latter are either concealed by, or more probably 
coalescent with, the broad mucro. But in Melicerita atlantica the lower border of the 
orifice is quite even, without any appearance of a mucro, nor have I been able to detect 
any upper internal denticles, indeed I am not quite sure of their existence even below. 
If of small size they may, however, be concealed by the chitinous investment and 
operculum. 
The relative dimensions of the zooecial areas in the three species are as under : — 
Melicerita charlesworthii, . . . 0 /A 01 5 x - 010 
Melicerita angustiloba, . . . . 0 //- 022 x '015 
Melicerita atlantica, . . . . 0"*025 x , 035 
and as the size of the areas in all three species appears to be remarkably uniform, these 
dimensions afford an additional differential character of considerable value. They also 
show that, so far as size is concerned, the recent form shows an advance 
upon its Miocene predecessors. 
The accompanying figures show the relative proportion of the 
in three species, drawn to scale and magnified about 50 diameters. 
a. Melicerita atlantica. 
b. Melicerita charlesworthii. 
c. Melicerita angustiloba. 
N.B. — As the only specimen of Melicerita atlantica is quite 
mentary, the account of its habit of growth is of course imperfect ; nor 
is it possible to say how it is rooted, whether radicate or fixed, but most probably, like 
the rest of the Salicornariadse, it is radicate. 
(2) ? Melicerita dubia, n. sp. (PI. XXXIII. fig. 1 0). 
Character. — Zoarium compressed, bilaminate, erect; composed of broad branching 
lobes of unequal width. Surface divided into uniform rhomboidal or hexagonal areas, 
angular at top and bottom, bounded by thick granular continuous ridges, and disposed in 
transverse series. Front much depressed, with a central rounded elliptical aperture, 
having a thick beaded or granular border, and the upper third occupied by a semicircular 
operculum ; the lower part membranous. A few vicarious avicularia on the edges of 
the branches or lobes, with an obtuse mandible pointing upwards (fig. 10c). 
Habitat. — Station 320, lat. 37° 17' S., long. 53° 52' W., 600 fathoms, green sand. 
I have had great difficulty in assigning its family position to this very remarkable 
species, and it is with great hesitation that I place it with or next to Melicerita in that 
of the Salicornariadse. The only other Family to which it might possibly be referred is 
(ZOOL. CHALL. EXP. PART, XXX, 1884.) Gg 13 
