I60 Happon anp Durrpen—Some Actiniaria from Australia and other Districts. 
outer row dark brown; disc blotched with brown; margin of mouth light-yellow ; 
cesophagus pinkish. 
Dimensions.—According to the coloured drawing sent to us by Professor 
Spencer, the diameter of the column would be about 35 mm., and its height about 
25 mm. 
Locality.—Port Philip. 
The single specimen we received was in a contracted condition. 
Body-wail (Pl. 1x., figs. 4, 5).—Thin ; ectoderm broader than mosoglea, regular, 
with numerous small nuclei; no cuticle present; weak muscle. Mesoglcea thin, 
with small cells. ndoderm thinner than the mesogloea, regular, crowded with 
dark granules; muscle weak. 
Acrorhagi (Pl. 1x., fig. 4.).—Ectoderm much as in body-wall, with numerous 
nematocysts ; mesoglceea thinner than in body-wall. The acrorhagi are cireum- 
scribed externally by a distinct sphincter which projects into the cavity of the 
stem, and which is provided with simple mesoglceal plaitings, mainly on the 
inferior aspect of the projection. 
Sphincter muscle-—The small, diffuse, endodermal muscle is situated near the 
base of the acrorhagi on their oral aspect; the plaitings of the mesogloea are 
mostly simple, though a few are very slightly complex. 
Tentacles.—Kctoderm very thick, crowded with extremely small colourless 
curved nematocysts ; muscle well developed on plaitings of the mesogloea. 
Mesogloea thin. Endoderm thick, and crowded with dark granules. 
Mesenteries (Pl. 1x., fig. 5).—Twelve pairs of perfect mesenteries, of which 
two pairs are directives. In the lower part of the column twelve pairs of small 
imperfect mesenteries alternate with these. The perfect mesenteries bear the 
gonads, which in this specimen were ova. The parieto-basilar muscles are well 
developed on simple plaitings of the mesoglea; on the side opposite to the 
retractor muscle is a thin pennon. ‘The retractor muscle is strongly developed, 
and appears as an elongated half-oval in section; the numerous long mesoglceal 
plaitings are simple and slightly branched. The mesogloea is moderately thin. 
The mesenterial filaments are crowded with small thin nematocysts. 
This species, while presenting an external similarity to A. Dixoniana, can be 
readily distinguished from that species both externally and anatomically ; for 
example, the character of the sphincter is different in the two species, and the 
alder species lacks the acrorhagial sphincter, while it possesses a distinct battery 
of nematocysts on those processes. 
