210 THE VOYAGE OF H.M.S. CHALLENGER. 
Fig. 2. Sporadopora dichotoma. Older specimen reduced in size to one-half of its 
dimensions to show the method of branching in the more fully grown 
specimens. 
Fig. 3. Spinipora echinata. Enlarged to twice the natural size. 
Fic. 4. Astylus subviridis. Several of the branches of the specimen are broken off. 
Natural size. 
Fig. 5. Stylaster densicaulis. Portions of a ccenosteum of the natural size. «a Portion of 
a tip of a branch enlarged. 
Fig. 6. Allopora profunda. Natural size. « Portion of same enlarged. 
. Errina labiata. Natural size. The form of the stem of the ccenosteum is much 
distorted in places by parasitic annelids. «@ Portion of a branch enlarged. 
= 
a 
go 
Saf 
PLATE II. 
Fig. 1. Section vertical to the surface of ccenosteum of Sporadopora dichotoma 
showing the structure of the hard parts. The general mass is seen to be 
excessively porous in appearance, being traversed in all directions by 
canals which, in the recent condition of the coral, contain the elements 
of the ccenosarcal meshwork. The perforations and canals are smaller 
towards the surface of the coenosteum, and coarser in the deeper regions. 
The cavities in the mass occupied by the zooids and gonophores are 
excavated within it, and have their walls freely perforated, like the 
remainder of the ccenosteum. 
GZ. Mouth of a gastropore. 
S. Style terminating above in a delicate brush of spicules. 
T. Thin calcareous tabula. 
DZ, DZ. Pores of large and small dactylozooids. 
G. Cavity or ampulla occupied by a male gonophore, which is in this 
genus entirely sunken beneath the surface of the ccenosteum. 
Fig. 2. View of the surface of the ccoenosteum of Sporadopora dichotoma as seen by 
reflected light. 
GZ, GZ. Mouths of gastropores. 
DZ, DZ. Mouths of dactylopores. 
G, G, G. Shallow depressions in which the ampulle open to the 
surface. 
Fig. 3. Portion of the ecenosteum forming a single calicular system of Stylaster den- 
sicaulis laid open by a vertical incision, in order to show the arrangement 
of the hard parts, and enlarged. 
GZ. Gastropore. 
