Hapvpon—TZhe Actiniaria of Torres Straits. 431 
MACRODACTYLA, n.g. 
Actiniidz, with the upper portion of the column covered with adhesive suckers ; 
no capitular rim or acrorhagi; tentacles long and stout, but not detachable; 
sphincter restricted ; with six pairs of imperfect mesenteries, and a second and 
third cycle of imperfect mesenteries ; all the mesenteries gonophoric. 
In the present state of our knowledge if seems necessary to define a new genus 
for the species formerly described as Condylactis aspera. In some respects it resem- 
bles one or other of several genera of this family, its combination of characters 
serving to distinguish it from any one of them. 
Macrodactyla aspera (H. & S.). 
(Pl. XXII., figs. 10, 11; Pl. XXVIII, figs. 3-5.) 
Condylactis aspera, Wadd. & Shackl., 1893; Proc. R. D. S., vut., p. 124. 
Form.—Column cylindrical ; skin delicate; the whole of the body except the 
disk covered with small, very adhesive suckers, so that whenever touched, this 
Actinian adheres to a foreign body like a Synapta; fragments of shells adhere 
to the body; large suckers occur on the upper portion of the column; mouth 
elongated; two gonidial grooves ; large tentacles in three or four cycles 
(6+ 6+ 12 +4 24= 48), the inner cycle much the largest; usually the tentacles 
are considerably swollen, but they can become quite slender and flaccid. 
Colour.—Body, uniform pale, translucent yellow, drab or buff, finely dusted 
with very minute brown spots, many of the suckers opaque white; tentacles 
translucent buff, slightly darker below, with three indistinct pale bands (one basal 
and two central); at the base is a dark patch ; oral disk amealy drab, with radial 
brown (mesenterial) lines, the primary and secondary radii; and to a less extent 
the tertiary also, with a cloudy mark not far from the base of each tentacle; 
between this and the dark basal patch of the tentacle is a whitish patch; a dark 
line round the mouth; cesophagus cream-coloured. 
Dimensions.—Column height, 30 mm., or more ; diameter about 25 mm. (1 in.) ; 
tentacles 60—75 mm. (23-3 in. long); extreme diameter of corona 175-200 mm. 
Habitat.—Surface of reef, Mer. 
In longitudinal sections of the column, we find that in the capitular portion of 
the column the body-wall is very thin, the greater part of the thickness being 
contributed by the ectoderm; the mesogloea is thin, and the endodermal plaits are 
comparatively small and sparse (Pl. xxvut., fig. 3). 
In the region of the suckers, the ectoderm is much folded and very deep at the 
ends of the suckers. The mesoglea is greatly thickened, and the plaits for the 
