Happon— The Actiniaria of Torres Straits. 475 
mouth rounded—two gonidial grooves; tentacles very numerous, forming a dense, 
very broad, marginal band, from which gradually diminishing bands of accessory 
tentacles extend for a variable distance along the disk, the larger radial groups of 
accessory tentacles extend towards the mouth for about three-fourths or more of 
the diameter of the disk. All the tentacles are short, columnar, and furnished 
with a spherical head with radiating lines from the apex. 
Colow’.—Very variable, ‘in one of the most ordinarily recurring varieties, the 
spheroidal, bead-like tentacles occur in irregularly mixed patches of grey, white, 
lilac, and emerald green; the disk being shaded with tints of grey, while the oral 
orifice is bordered with bright yellow.” In a rarer variety ‘‘ the oral centre was 
yellow, the general surface of the disk fawn-brown, and all the tentacles were a 
brilliant apple-green.” The column may be greenish blue, somewhat brown 
above with mauve suckers; oral disk purple brown, but green round the mouth; 
gonidial lips tipped with magenta; tentacles brown, deep dark blue heads. 
Another variety was dark sea-green, with lilac suckers; tentacles white below, 
yellowish above; disk translucent grey. 
Dimensions.—Expanse of oral disk from 1 foot to 18 inches (800—450 mm. ). 
Habitat.—At about half or three-quarters ebb. The tropical coasts of Aus- 
tralia. This species has the same distribution as, and is found along with, 
D. Kenti. 
The foregoing description is largely compiled from the accounts of this species 
given by Saville-Kent. This author draws attention to the fact that a fish and a 
prawn are commensal with the polyp in Torres Straits. This fish is the brilliantly 
coloured Amphiprion bicinetus, one of the Pomacentride, and allied to the 
wrasses ; the fish has two white transverse bands on a ground colour of orange 
vermilion. The prawn is perhaps a Palemon; it is quite transparent, save 
for some yellow and deep-red spots. In Western Australian waters another 
species of Amphiprion is associated with the Actinian; it has three white bands 
and other distinctive characters, which Saville-Kent describes in his later 
volume. 
Body-wall.—The structure of the body-wall in this species is very similar to 
that of D. Kenti, but I do not find deeply staining nuclei in the mesogloea as in 
that species. The mesogloea appears to have a fibrilar structure, the fibrils 
running for the most part parallel to the body-wall. The endoderm is destitute 
of zooxanthelle. 
Sphincter Muscle.—The circumscribed endodermal sphincter is much weaker 
than that in D. Kenti. The mesoglceal axis is short, narrow in the proximal part, 
and splays distally into an irregular fan-shape, from which finer plaitings are 
given off, which again give off short branches arranged in an irregularly pinnate 
manner (Pl. xxx1., fig. 8). 
8 Z 2 
