228 J, H. ASHWORTH. 



a thin film of mesogloea, and by a layer of endoderm cells, many of 

 which contain from two to five nuclei. 



8. The longitudinal canals which traverse the mesogloea of the stem 

 are very well developed, and are physiologically, and possibly morpho- 

 logically, equivalent to the ccenenchymal tubes of Heliopora coerulea. 



9. The nervous system is similar to that of Alcyonium ; the stellate 

 cells immediately outside the endodermic muscle-fibres are very clearly 

 seen. 



10. A complete series of developing polyps is described, beginning 

 with very young specimens, in which the tentacles are devoid of 

 pinnules, and ending with the adult polyps with multi-pinnuled 

 tentacles. 



11. A similar series of polyps of Heteroxenia Elizabethce is described 

 and compared with the siphonozooids of the same colony. It is 

 concluded that Heteroxenia is undoubtedly dimorphic, as stated by 

 Kolliker and Bourne. 



12. The origin of the buds of Xenia Hichsoni from the superficial 

 canal system, their subsequent growth, and the appearance in them of 

 the mouth, stoinodseum, siphonoglyph, gland cells in stomodeeum, 

 mesenteries, dorsal mesenterial filaments, and flagella of the endoderm 

 cells are traced. It is remarkable that the sexual cells are already 

 differentiated in a young polyp '95 mm, long. 



LITERATURE. 



1833. Qtjot et Gaimard. — 'Voyage de 1' Astrolabe,' tome iv., "Zoologie," 

 Paris, 1833. 



1874. Kolliker, A. — "Heteroxenia," ' Festschrift der Physical. -Med. Gesell- 

 schaft in Wurzburg,' p. 13, 1874. 



1876. Moselet, H. N. — " On the Structure of a Species of Millepora occurring 



at Tahiti, Society Islands," ' Phil. Trans.,' vol. clxvii , part i., 1876. 



1877. Klunzinger, C. B. — 'Die Korallthiere des Rothen Meeres,' erster 



Theil, " Die Alcyonarien und Malacoderrnen," Berlin, 1877. 



1881. Moselet, H. N. — ' Challenger Reports,' Zoology, vol. ii., Corals, 1881 

 (Heliopora and Sarcophyton). 



1883. Hickson, S. J. — " On the Ciliated Groove (Siphonoglyphe) in the 

 Stomodaeuin of the Alcyonarians," ' Phil. Trans.,' part iii., 1883. 



1883. Wilson, E. B — " The Development of Renilla," ' Phil. Trans.,' part iii., 

 1883. 



