Happon—The Actiniaria of Torres Straits. 425 
the mesogloeal plaiting of the ectoderm muscular layer is very prominent and 
distinct. 
Disk very similar to tentacles, but plaitings less marked. 
Mesenteries. —Longitudinal muscles very well developed (Pl. xxvu., fig. 2); 
pennons somewhat larger than in A. Papuensis. The basal muscle on the same 
side as the longitudinal muscle also well developed. Filaments much convoluted 
appear to consist of numerous rays or branches; the epithelium at the ends of these 
resembles more nearly the ectoderm of the cesophagus than the remainder. 
Gonads on most of the mesenteries, the directives may be fertile. 
Specimen A.—This male specimen possesses two well-marked pairs of directives 
and an obscure directive area, in which only one directive is well developed, and 
twelve pairs of non-directives. One pair of directives is infertile; on each of it is 
a pair of small mesenteries ; the pair on the one side appears first (in a series of 
sections from above downwards), but it never possesses mesenterial filaments; the 
pair on the other side do not extend beyond the endoderm. Next to this pair is 
a pair of which the one nearer the directives is small and infertile, whereas the 
other is large and fertile ; a large pair of fertile mesenteries follows, and then 
comes a pair of fertile directives. This is followed by three pairs of fertile mesen- 
teries ; the next is a well developed directive mesentery, which is fertile in its 
lower portion. Two peculiar mesenteries follow; they are very thin, and much 
folded ; they have no longitudinal muscles, but their small pennon muscles look 
towards one another; these follow two very inconspicuous incipient mesenteries, 
which are followed by another singular mesentery, also very thin and folded, 
with no longitudinal or pennon muscles, but it appears to be fertile at the very 
base of the polyp; this may be an undeveloped pair to the single directive. Two 
large fertile pairs of mesenteries follow, and then a pair of which the element 
nearer to the infertile pair of directives is small and infertile, whereas the other 
is large and fertile; between this pair and the infertile directives is the rudi- 
mentary pair of mesenteries mentioned above. 
The formula of this specimen may be written thus :— 
D3 D38d2d4=15. 
I have taken the two (?) half-directives as forming one pair in the total of 
fifteen pairs of mesenteries. 
Specimen C.—This specimen has five pairs of directives and thirteen pairs of 
non-directives; the mesenterial formula is 
D+24+D4+24+D424+D424+D+4+5=18. 
One pair of the second series of two pairs is rudimentary, and one or two of 
the other mesenteries are smaller than their fellows, but nothing of interest was 
TRANS. ROY. DUB. SOC., N.S: VOL. VI., PART XVI, 8R 
