72 Mr Gardiner, On the Anatomy of a supposed 



On the Anatomy of a supposed New Species of Goenopsammia 

 from Lifu. By J. Stanley Gardiner, M.A. 



[Received February 6, 1899.] 



The investigation is based on numerous small colonies obtained 

 by Dr Willey from the reefs of Lifu, Loyalty Islands, at low tides. 

 The species is described as new under the name of Goenopsammia 

 willeyi. The genus is one of the simplest of the colonial perforate 

 Madreporaria, and the species is without commensal zooxanthellae 

 and hence feeds entirely through its stomodoeum. 



For the structureless lamella or jelly, instead of a makeshift 

 term such as mesogloea, the name skeletogloea is proposed, a term 

 which agrees well with its main function, both in the Hydrozoa 

 and in the Anthozoa, i.e. that of support. 



The corallum lies completely outside the polyps, and is 

 separated from them by the calicoblastic ectoderm, a thin layer 

 of tissue swollen out in places by the nuclei. The skeletogloea is 

 at the bases of the mesenteries and of the dividing walls of the 

 coenosarcal canals directly attached to the corallum by fibrillated 

 bundles, which broaden out greatly at their attaching ends. The 

 interspaces between these bundles are filled by calicoblastic 

 ectoderm. These bundles are identical with the calicoblasts of 

 von Heider, and there is no evidence to show that the corallum is 

 formed by the complete calcification of cells. In five genera of 

 Madreporaria no trace of organic matter was found in the corallum, 

 and there is no reason to doubt von Koch's conclusion that the 

 corallum lies completely outside the animal and is the result of 

 secretion by the calicoblastic ectoderm. 



Two kinds of nematocysts are found, the one forming large 

 batteries on the tentacles but found also throughout the whole 

 free ectoderm, the other found principally in the mesenterial 

 filaments but also in the external and stomodoeal ectoderms. 



The tentacular nematocyst is about "027 mm. in length and 

 has a fine thread, spirally coiled about 24 times under the external 

 membrane, which is somewhat pushed out over it. The whole 

 nematocyst is extruded and in its place appears a mass of proto- 

 plasm, the central part of which acquires a definite membrane. 

 This is the young nematocyst and is about twice as long and 

 broad when ripe. Its protoplasm next becomes finely granular; 

 the granules fuse together into large granules, which arrange 

 themselves in a spiral manner under the external membrane. 

 Finally, by contraction of the whole nematocyst and by complete 

 fusion of the granules the ripe nematocyst is produced. The 



