MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERID2E. 
455 
A diagrammatic view of a cyclo-system, as viewed from above the mouths of the 
pores, is given in Plate 35, fig. 13. The styles are supposed to be brought into view 
by deep focussing of the lens. The form and arrangement of the pores are almost 
exactly similar to that already described as occurring in Stylaster. 
The very small ampullae are spherical cavities, which are usually entirely sunk 
beneath the surface, but sometimes near enough to it in situation to raise upon it 
very small conical elevations, which easily escape notice, and are present only here and 
there. The ampullae are present in abundance in the walls of the pore systems and 
at their bases. 
Soft Structure of Allopora profunda. 
Cccnosarc . — A surface layer of ectoderm covers the surface of the coral, as in Stylaster 
densicaulis, and is reflected into the pores to form the sacs of the zooids. The 
coenosarcal canals form a fine superficial reticulation at the surface of the coral, beneath 
the surface layer, and spring from a deeper meshwork of larger canals which, as in the 
Stylaster already described, have a mainly longitudinal course within the thickness of 
the walls of the pore systems, parallel to the axes of the systems, and lead almost 
directly from the bases of the dactylozooids with which they anastomose to the large 
canal offsets given off at the periphery of the bases of the gastrozooids. At the inner 
surface of the gastropore are finer canals springing from tins main meshwork, and from 
these spring a series of offsets which pass in a direction radial to the axis of the gas- 
tropore, to abut on and become united with the outer surface of the sac of the 
gastrozooid. « 
The radial offsets are disposed irregularly, at unequal distances from one another, and 
at all heights in the gastropore (Plate 39, It Pi). The inner ends of the radial offsets are 
often enlarged where they abut on the wall of the sac of the gastrozooid, and they are 
often forked at then’ outer extremities, where they spring from the coenosarcal meshwork. 
They appear to be homologous with the radial canals already described as occurring in 
a similar connexion in Sporadopora dichotoma (Plate 43, fig. 3). In transverse sections 
of a zooid system, these radial offsets have much the appearance of mesenteries of an 
Anthozoan coral cut across, and in some sections the} 7 show a certain amount of regularity 
in disposition at the particular level selected for the cut (Plate 44, fig. 12). 
These radial structures are here termed offsets, and not canals, because, although in 
some instances they appear to be similar in construction to the ordinary coenosarcal 
canals, and usually show similar structure to these at their outer extremities, they 
usually consist towards them middles and inner extremities of simple bands of trans- 
parent fibrous tissue. The exact structure could not be determined, but it seems 
probable that these radial bands represent radially disposed offsets of the canal mesh- 
work, which have become developed into fibrous organs with an elastic or muscular 
function, which is brought to bear on the zooid sac. In the case of the radial canals 
of Sporadopora dichotoma, distinct muscular elements were observed as forming part 
of their structure. 
3 N 
MDCCCLXXVIIT. 
