MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERlDvE. 459 
The lower chamber of the gastropore is a cavity with a rounded bottom, which is 
excavated within the substance of the branch supporting the pore system. The cavity 
communicates with the upper chamber by the horseshoe-shaped opening, and with 
the dactylopore as already described. With adjacent cyclo-systems it communicates 
by means of the axial canals of the branches. There is no trace of a style at the 
bottom of the gastropore. 
Around the mouth of the gastropores the mouths of the dactylopores appear as 
elongate slit-like openings, radially directed towards the axes of the systems. The 
outer peripherally-placed margins of these slits are rounded, whilst internally the slits 
join the cavity of the gastropore. The pseudosepta intervening between the dactylo- 
pores are, in origin, double laminae, as in Stylcister densicaulis, but in the present form 
appear as thin plates, which have so regular a radial arrangement and so wide an 
extent that they simulate the septa of Hexaetrinian corals more closely than do those 
of any other Stylasterid. 
The inner extremities of the summit borders of the pseudosepta by their arrange- 
ment form a circular aperture leading to the cavity of the gastropore. There are from 
eighteen to twenty-one dactylopores in each cyclo-system. The upper wide slit-like 
chambers of the dactylopores are continued into small short tubular cavities below, as 
in Stylaster densicaulis; but these are entirely devoid of a style. The mouths of 
these tubular cavities are set in a circle, at the bottoms of the interspaces between the 
pseudosepta, at points about equidistant between the inner extremities of tire pseudo- 
septa and the outer margins of the chambers which they enclose (Plate 35, fig. 15). 
The ampullae are confined to the zones around the pore systems, and do not occur 
on the branches. Their cavities are usually kidney -shaped. 
Soft Structures of Astylus subviridis. 
The general arrangement of the soft structures is represented on Plate 41, fig. 1. 
Ccenosarc. — The usual surface layer is present, which is continuous with the sacs of 
the zooicls. A fine superficial reticulation of smaller coenosarcal canals (Plate 41, 
fig. 1 , S, S) extends over the surfaces of the branches and ampullae, and coral generally, 
beneath the surface layer. The axes of the branches are occupied by mesh works of 
large canals, which lead from one cyclo-system to another, and place the whole of the 
systems in free communication with one another. 
Large canals are given off from the periphery of the gastrozooids. Some of these 
communicate directly with the axial meshwork of canals, whilst another set passes 
upwards in the wall of each cyclo-system to join, after a certain small amount of 
ramification and anastomosis, the basis of the dactylozooid. From the surface of the 
meshwork of these latter canals, which adjoins the dactylopore cavity, a few transverse 
smaller canals are given off, which pass inwards radially to be attached to the wall of 
the pore-sac, and represent the more fully-developed “ radial offsets,” already described 
as occurring in Allopora profunda (Plate 41, fig. 1, It). 
