474 Happon— The Actiniaria of Torres Straits. 
Amphiprion percula, Lacepede. On thrusting a stick into the oral orifice of the | 
anemone the fish swim out, but return immediately to their residence within the 
gastric cavity of their host, on the removal of the stick. The ground colour of 
the fish is a bright orange-vermilion, interrupted by three pearly white cross- 
bands, which as well as the edges of the fins are bordered with black ; in an 
allied species the red colour is replaced by black. Apparently several species of 
Amphiprion are commensal with this gigantic anemone, as is also a small flat crab. 
Body-wall.—The body-wall is thin relatively to the great size of the polyp. 
The ectoderm is thrown into numerous elevations, similar to those described by 
MMurrich for S. (Discosoma) anemone (M°Murrich, 1889, p. 39, pl. 1i., fig. 16). 
These give to the surface of the column a slightly rough appearance in spirit 
specimens. The ectoderm in S. Ken/i consists entirely of ciliated columnar cells, 
the structure of the verruce being similar to that of other parts. The mesoglea 
is about as thick as the ectoderm, for it contains very numerous deeply staining 
nuclei, which appear to be drawn out into fine fibrils. There is a well-marked 
endodermal muscular layer. ‘The endoderm contains numerous zooxanthellze. 
Sphincter Muscle—There is a strong circumscribed sphincter muscle (Pl. xxx, 
figs. 6, 7). The mesoglceal axis is very thick, and rather short, and has a tendency 
to divide into two branches. The fine mesogleeal plaitings are very numerous and 
intricate, occasionally anastomosing, so that some muscle fibres are completely 
enclosed in the mesoglea. This occurs most markedly on the proximal aspect of the 
sphincter; that is, on the side towards the column, and away from the tentacles. 
Disk and Tentacles —The nervous layer of the ectoderm of the tentacles is well 
marked. The ectodermal muscular layer is weak. The endodermal muscular layer 
is, however, well developed, the fibres being supported by irregular, blunt meso- 
gloeal processes. The structure of the mesogloea is similar to the body-wall. 
Mesenterics.—There are a great number of perfect mesenteries. There is a 
pair of directives at each of the two gonidial grooves; the arrangement of the rest 
of the mesenteries appears to be quite irregular. 
Stoichactis Haddoni (8.-K..). 
Discosoma Haddoni,8.-Kent, 1893—“ The Great Barrier Reef of Australia,” pp. 32, 
144, photo pl. xxi., chromo pl. 11.—Saville-Kent, 1897, “The 
Naturalist in Australia,” p. 221. 
(Pl. XXXI., fig. 8.) 
Form.—Column massive, soft, upper portion with a comparatively narrow zone 
of somewhat crowded suckers; a slight but distinct crenulated parapet. Oral disk 
of much greater diameter than the column, and thrown into deep, irregular folds ; 
