Reprinted from the " Quarterly Journal op Microscopical Science," 



Vol. 42. 



THE STRUCTURE OF XENIA HICKSONI, NOV. SR, WITH 

 SOME OBSERVATIONS ON HETEROXENIA ELIZABETHS, 

 KOLLIKER. 



By J. H. Ashworth, D.Sc. (Lond.), Demonstrator in Zoology, 

 Owens College, Manchester, 



With Plates XVIII.— XXII. 



Contents. 



PAGE. 



Introduction 181 



External Characters of the Colony : Polyps, Tentacles, Pinnules - 182 



Diagnosis of the Species Xenia Hicksoni - 185 



General Anatomy : Stomodseum and Mesenterial Filaments ; Ccelen- 



tera of Polyps ; Mesoglcea, its canals and Cells - - - - 186 



Ectoderm . Nematocysts, Spicules -.--.-- 191 



Mesenteries : Mesenterial Filaments, Cells in Mesogloea of Mesenteries 196 



Endoderm : Giant Flagella --------- 198 



Mesoglcea : Superficial and Internal Canal Systems ; Cells in Mesogloea 200 



Spermatogenesis 207 



Nervous System 209 



History of our KnoAvledge of the Buds of Xeniidce .... 210 



External Characters of the Buds of Xenia Hicksoni . - - - 213 

 External Characters of Heteroxenia Elizabeths ; of its young Polyps 



and of its Siphonozooids -------- 216 



Internal Anatomy of Heteroxenia, Autozooids, Siphonozooids, Stem - 219 



Origin and Internal Structure of the Buds of Xenia Hicksoni - - 221 



General Summary 227 



Literature 228 



Introduction. 



At the suggestion of Professor Hickson I undertook to examine a 



specimen of the the Alcyonaceous coral Xenia, which he had collected 



on the reefs of Talisse Island, North Celebes, chiefly with the intention 



