548 OLWEN M. KEES. 



including two pairs of directives ; in another there are 36 mesenteries, 

 including one pair of directives ; and in a third there are 46 mesenteries, 

 including two pairs of directives. 



There are two cycles of mesenteries (Fig. 14), a primary series, consist- 

 ing of complete ones, and a secondary series in which they are incomplete. 

 The incomplete mesenteries project for some distance into the ccelen- 

 teron ; in section they are nearly as broad as the primary mesenteries. 

 The parieto-basilar muscle is stronger than that represented in the 

 figure of C. myrcia and passes gradually into the retractor muscles. There 

 is a constriction of the mesogloea at the point where it passes from the 

 mesentery into the body-wall. The folds of the retractor muscles are 

 more numerous than those of C. myrcia, and consist of a number of un- 

 branched club-shaped processes which project into the endoderm. 



A serial summary is appended showing anatomical characters of the 

 various species of Corynactis in so far as these data have been obtainable. 

 The ordering of tentacles and mesenteries, though frequently tetramerous, 

 appears to be highly variable, and, pending further study, these features are 

 omitted from the present summary. 



Corynactis viridis, Allman, 1846 (British). 



Sphincter (endodermal in all species) feeble and diffuse in the lower 



part, stronger above, mesogloeal processes branched. 



Mesogloea thin. 



One oesophageal groove. 



C. myrcia, Duchassaing et Michelotti, 1866 (Jamaica). Anatomical data 

 from Duerden. 



Sphincter as in C. viridis, but weaker, mesogloeal processes unbranched. 

 Mesogloea thicker than the ectoderm. Endoderm thicker than in 

 C. viridis. 

 No oesophageal groove. 



C. carnea, Studer, 1878 (Buenos Ayres). Anatomical data from Kwietniewski 

 [23]. Sphincter strong, fibres long and branching ; mesogloeal pro- 

 cesses branched. Mesogloea about as thick as ectoderm, sometimes 

 thicker. 

 Two pairs of directives, grooves weak. 



C. Jioflites, Haddon and Shackleton, 1896 (Torres Straits), Anatomical data 

 from Haddon. 



Sphincter strong but diffuse. Mesogloeal processes sHghtly branched. 

 Mesogloea about as thick as the ectoderm. 

 Two pairs of directives and one groove. 



