686 Reports on the Zoological Collections made in Torres Straits, 1888-1889. 



In some places these plaitings appear to unite to form a distinct band of mesogloea, 

 outside the muscle fibres, so that here the muscle may be regarded as mesogloeal. 

 The endodermal muscular layer is well developed, especially at the bases of the 

 mesenteries, but it is not at all so remarkable as is that of tlie ectoderm. The 

 endoderm, as well as mesogloea, is relatively thin in the tentacles. The endoderm 

 contains numerous zooxanthellse. 



(Esophagus. — The ectodei'm of the oesophagus is thrown into slight and irre- 

 gular folds. The groove is only indicated by a slight depression in the region 

 of the sulcar directives. Both mesogloea and endoderm form very thin layers. 

 Nematocysts are present in the endoderm similar to those found in the endoderm 

 of the mesenteries and column in this region. 



Mese?iteries. — The arrangement of the mesenteries is brachycnemic. The im- 

 perfect mesenteries are well developed, sometimes extending about half way from 

 the body- wall to the oesophagus (PI. lxiv., fig. 9). The ectoderm of the oesophagus 

 is reflected a short way above the lower opening of the oesophagus, and forms the 

 mesenterial filaments in the usual way. The mesogloea of the mesenteries is 

 comparatively well developed even in the oesophageal region, but it becomes much 

 thicker as it descends. Several canals run vertically through each mesentery. 

 Some of those appear to be connected in the coenenchyme with the endoderm 

 (PI. LXiii., fig. 5). It is possible that others are connected with ectodermal 

 canals or lacunae, but we have not been able to trace any to the ectoderm. The 

 endoderm of the mesenteries is very similar to that of the body-wall. It 

 contains numerous small oval nematocysts. The muscles are fairly well 

 developed. The mesogloea on each side of the mesentery, close to the body- 

 wall, is thrown into numerous and often branching plaits, which supjiort the fibres 

 of the parieto-basilar muscle (PL lxiv., fig. 9). On one side of each mesentery the 

 mesogloea is thrown into very slight plaits all the way up. These plaits support 

 the longitudinal fibres. On the other side, the parieto-basilar fibres (cut obliquely 

 in transverse section) extend considerably beyond the mesogloeal plaitings. In 

 the imperfect mesenteries the mesogloeal plaitings extend the whole way on both 

 sides, and it is hardly possible to distinguish two distinct sets of fibres. 



Gonads. — In only one of our specimens did we find gonads. These were all 

 female ; but they were few and not fully developed. We cannot say with 

 certainty whether this species is monoecious or dioecious, though our evidence 

 leads us to suppose it to be the latter. 



Gemmaria, Duch. & Mich., 1860. 



Solitary brachycnemic Zoantheae with mesogloeal sphincter muscle. The body- 

 wall is incrasted with grains of sand and spicules. The ectoderm is usually 



