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Contributions to the Comparative Anatomy of some 



British Actiniae. 



By 

 Olwen M. Rees, B.Sc, 



Zoological Department, Univcrsih/ College of JValcs, Aberystiryt.h. 

 With Ficriues 1-16 in the Text. 



The main object of this paper is to give a comparative anatomical 

 description of some British Anemones as well as to describe each in- 

 dividually ; but the account is not so full as it was expected to be, as 

 it was not possible to get all the species required. 



In most cases the specimens were examined externally before sections 

 were cut. Each specimen was prepared according to the usual method 

 used with paraffin wax, and I found during the progress of the work 

 that borax carmine was the stain which gave the most satisfactory 

 results. 



I should like to thank Miss E. de Fraine, D.Sc, Mr. F. W. Durlacher, 

 and Mr. F. S. Wright for much assistance in the course of the work. 



For specimens collected and sent I am deeply indebted to Dr. E. J. 

 Allen and his staff at Plymouth, ]\Iiss Delap, of Valentia Island, and 

 Monsieur Louis Fage, of the Laboratoire Arago, Banyuls-sur-Mer, 

 France. 



Fam. SAGARTID-ai (Gosse, 1858). 



" Actiniinee with a contractile pedal disk ; body- wall smooth, or 

 provided with verrucas or tubercles, and usually perforated with cinclides, 

 with or without a cuticle. Tentacles usually numerous and retractile, 

 not very long, smooth, simple and generally entacmaeous, sphincter 

 muscle characteristically well developed and mesogloeal, occasionally 

 diffuse endodermal, or even absent. At least six pairs of mesenteries, 

 may be fertile or sterile. Acontia present." The above is the definition 

 used by Haddon in " The Actiniaria of the Torres Straits " in 1898. 

 There has been a great deal of discussion concerning this family. 



Many other authors in defining the family include the provision of 

 the " sphincter muscle mesogloeal." This is not important, as Bourne 

 has shown the presence of an endodermal sphincter in Metridium (Actin- 

 oloba). Again, other authors define this family as " Hexactinise furnished 

 with acontia." 



NEW SEltlES. — VOL. X. XO. 4. MAY, 1915. 2 L 



