454 MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERHLR. 
The gastrozooids in the present form, and their tentacles, are so short that it seems 
improbable that these zooids are able to emerge from the summit of the gastropore in 
the expanded condition of the coral. The dactylozooids probably become, when active, 
long and filiform, and acting as tentacles bend inwards to supply the gastrozooid with 
food. 
Gonophores. — Only male specimens of Stylaster densicaulis were obtained. Each 
male ampulla contains two or three ovoid gonophores, which are attached to large 
offsets of the ccenosarcal meshwork at one end of their longer axes. They have an 
internal spadix, and in finer structure seem to differ very little from those of Spora- 
dopora. They are shown as seen through the transparent walls of the ampullar sacs 
in Plate 40, G G. 
(6.) GENUS ALLOPOBA (EHRENBERG). 
To this genus I have referred a coral dredged off the mouth of the La Plata, on 
account of the very considerable irregularity with which the pore systems grow out 
from one another. The coral seems to represent a species hitherto undescribed, which 
I term Allopora profunda. 
Corallum of Allopora profunda, sp. n. (H. N. M.) 
The corallum (Plate 34, figs. 6 , Ga) is composed of a stout stem, bearing numerous 
branches. The branches ramify to some extent in the same plane, so as to form a sort 
of flabellum ; but this flabellum is curved considerably in the direction of its height, 
and its lateral margins are also bent over sharply towards the same curved face. The 
main stem has a sinuous course, and the branches are all more or less curved in direc- 
tion. The stem and branches are oval in transverse section, being flattened in the 
plane of the flabellum. The corallum is white, and its surface is minutely granular. 
The pores occur in regular cyclo-systems ; when young they project from the terminal 
branchlets in the form of small cylindrical masses, which are slightly expanded in 
diameter at the free extremity. These cyclo -systems show a tendency to a regular 
alternate arrangement, the base of each system abutting on the side of the prece din g, 
and the axes of the systems being inclined to one another at an angle of about 45° in 
the general plane of the flabellum. This tendency is, however, to a large extent 
obscured by irregularities. One face of the flabellum, viz., that rendered convex by 
the curving of the whole mass, is entirely devoid of cyclo-systems ; whilst a consider- 
able number are scattered over the surface of the branches on the concave face. As 
the branches thicken by growth of coenenchym, the cylindrical masses of the cyclo- 
systems become buried, and only their free ends remain in view, as the mouths of pore 
systems on the surfaces of the branches. Even these mouths become partially over- 
grown in the active regions of the coral, and in the older parts of the stem frequently 
obliterated. The cyclo-systems consist of a deep gastropore, provided with a style, and 
surrounded by from twelve to sixteen dactylopores. The dactylopores are provided 
with a small hirsute style, as in Stylaster densicaulis, 
