REPORT ON THE XENIIDAE COLLECTED BY DR WILLEY. 



By J. H. ASHWORTH, D.Sc, 

 Demonstrator in Zoology, Owens College, Manchester. 



With Plates LII. and LIII. 

 CONTENTS. 



PAGE 



Introduction 509 



Xenia crassa, Schenk ................ 510 



X. memhraaacea, Schenk ............... 512 



X. umhellata, Savigny 513 



X. viridis, Schenk 516 



New Species. X. Novae-Britanniae, Ash worth 518 



Diagnosis of the Species Xenia Xovae-Britanniae, Ashworth ........ 521 



Habits, Distribution and Classification of the Xeiiiidae ......... 522 



General Internal Anatomy ............... 523 



Stomodaeum and Mesenterial Filaments ............ 523 



Coelentera of Polyps 525 



Mesogloea, its Canals and Cells 525 



Ectoderm 526 



Endoderm .................. 526 



Gonads 526 



Literature 528 



Dr Willey's collection of specimens of the genus Xenia contains fifteen colonies 

 which may be referred to five species. 



Of the sixteen species of Xenia hitherto described eight were founded by 

 Schenk (1S96)' upon specimens brought from Ternate (Moluccas). Three of the 

 specimens in Dr Willey's collection belong to three of these newly described species, 

 which are now recorded for the second time only. One of the other two species is 

 moderately well-known, being, in fact, the fir.st described species of Xenia (X. unibellaia, 

 Savigny) ; the other species is new and is represented in the collection by eight 

 specimens. Thus although four of the species have been previously described three of 

 them have hitherto been met with only once, and as all the specimens are of considerable 

 interest a brief description of each is given below. 



' The dates in brackets form references to the list of papers given on p. 528. 

 W. IV. 68 



