QtEENSLAKD AND THE NEW HEBKIDES. 319 



Colour. — Sand-colour in spirit. No account of colour when living enclosed. 

 Dimensions. — Height 2-8 mm., average 2-5 mm. ; diameter of capitiiliim 

 2-3' 5 mm. 



Locality. — Collected in Erikor Lagoon, Sandwich Island, New Hebrides^ 

 by Mr. Douglas Mawson, B.E., B.Sc, in 1903. Part of a colony. 

 Numerous specimens. 



The specific name refers to its undoubted relationship to Z. sandvicensis. 

 Column-wall. — Distinctly thinner than in Z. sandvicensis, averaging '19 mm. 

 in place of '29 mm. (PI. 44. fig. 8). The ectoderm is discontinuous ; a cuticle 

 and subcuticle are present. The cavities in the mesogloea in which the ecto- 

 derm lies are more irregular than those of Z. sandvicensis and contain a larger 

 amount of cellular tissue, indeed the latter may occasionally fill the mesoglceal 

 spaces. In this smaller species endodermal fibres extending through the 

 mesogloea are more numerous than in Z. sandvicensis, but the general structure 

 of the column-wall is very similar in the two species. 



Sphincter muscle (PI. 44. fig. 9). — This is double and strong, consisting of 

 small rounded and irregular cavities which extend through the greater width 

 of the mesogloea. The muscle-lining is thin and free muscle-cells are present 

 in all the cavities. Large quantities of diatoms are caught in the ridges 

 of the capitulum in this region. 



Tentacles. — Number 50, 54, and 56 in three specimens examined. The 

 ectoderm and mesogloea resemble those of Z. sandvicensis ; large oval, and 

 small narrow, nematocysts are present, but the oval refractive bodies of 

 Z. sandvicensis are absent. The endoderm contains fewer zooxanthell^ and 

 the lumen is larger. 



Disc. — The structure of the ectoderm and mesogloea resembles that of the 

 tentacles, but the endoderm is much narrower and contains fewer zooxanthellse. 

 Only the large oval nematocysts are present in the ectoderm, which is not 

 granulated as in the last species. 



GEsopliagus (PI. 44. fig. 10). — The structttre of the oesophagus resembles 

 that of Z. sandvicensis, Z. Jlos marinus, and Z. cliiercliice (3, 6_, and 8). The 

 folding of the oesophagus is always unsymmetrical. Nematocysts are very 

 numerous in the ectoderm. 



Mesenteries (PL 44. fig. 10). — The mesenteries number 50-56. In this 

 species all the perfect mesenteries including the sulcar directives are of equal 

 thickness and the basal canal is oval. The musculature is well developed, the 

 longitudinal retractor muscles on plaitings of the mesogloea. Nematocysts 

 are present in the endoderm and zooxanthellee are very abundant, but, as in 

 Z. sandvicensis, these latter are absent below the level of the oesophagus. 



Gonads. — All the six polyps cut were fertile, and the gonads well developed, 

 ripe and numerous. Three were male individuals, and three female. This is 

 the first instance recorded of both male and female individuals being present in 

 one colony of Zoanthus. Haddon and Shackleton mention that they did not 



