68 THE VOYAGE OF H.M.S. CHALLENGER. 
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 the pseudo- 
septa and the outer margins of the chambers which they enclose (PLE ies 15); 
The ampulle 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 VIII. fig. 1. 
Cenosarc.—The usual surface layer is present, which is continuous with the sacs of 
the zooids. A fine superficial reticulation of smaller ccenosarcal canals (Pl. VIII. 
fig. 1, SS) extends over the surfaces of the branches and ampulle, and coral generally, 
beneath the surface layer. The axes of the branches are occupied by meshworks 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 ocewring in Allopora profunda (Pl. VIII. fig. 1, R). 
The ampullar sacs are embedded in a meshwork of offsets of the larger canals, and 
each of the gonophores is attached to one or more stout canal branches. 
Stout offsets of the deeper canal meshwork traverse the interior of the pseudoseptal 
lamin, and especially near the summits of the pseudosepta large tortuous branches 
pass radially outwards between the dactylozooid sacs, and, branching at their outer 
extremities, join the surface network at the margins of the cyclo-systems (Pl. UX. fig. 2). 
Just over the outer extremities of each of the pseudosepta, at the margin of the top of 
each cyclo-system, and in the angles between the outer margins of the dactylopores, 
are situated ovoid nematophores. A single nematophore is placed in each above- 
described position, The nematophores are ovoid sacs, closely packed with about three 
tiers of nematocysts of the larger form, placed with their longer axes parallel to those 
of the containing sacs (Pl. LX. fig. 2, N). 
The endoderm of the soft parts in the present form were observed to have, in the 
fresh condition, a dusky bluish-ereen colour, with which the whole ccenosare and 
zooids of the recent animal when dredged were seen to be tinged. The pigment is 
soluble in alcohol, and yields a green solution, which produces a well-marked absorption- 
