1909.] N, Annandale : An Anemone without tentacles. 159 



transverse nerve-fibres can be detected with some difficulty. This 

 is clearly the so-called nervous layer. 



Inside the nervous layer is a considerably broader one, which 

 also consists fundamentally of mesoglcea but is noteworthy for the 

 fact that it contains numerous bundles of longitudinal muscle- 

 fibres, which in cross-section appear as slightly oblique transverse 

 bars or narrowly oval masses. Often they are arranged in such 

 a way that two succeeding bars form an angle with one another. 

 At the inner end of these longitudinal m.uscles is a narrow but very 

 distinct ring of circular muscle-fibres. An examination of the 

 body-wall from the inner surface shows that these circular muscle- 

 fibres form a series of parallel rings extending from the upper end 

 to the base of the column, at the two ends of w^hich the}' are rather 

 stouter than they are in the middle. There is not, however, a 

 regular sphincter at either end. 



The endoderm of the body- wall consists of rather long, highly 

 vacuolated cells. The cilia with which they are provided are barely 

 visible in my sections. At the base of man}- of these cells peculiar 

 sausage-shaped bodies are present, each containing two or more 

 round structures which take up eosin very strongly. Probably these 

 bodies are micro-organisms of some kind. 



In a transverse section of the body-wall, opposite the middle 

 of the stomodseum of a fully expanded specimen, the ectoderm is 

 the broadest of the apparent layers, occupying more than a third 

 of the total thickness {i.e., about 0*4 mm. out of a total of ro6 mm.). 

 The whole of the mesoglcea is consider abl}' narrower, occupying 

 about o"3 mm. ; of this one- third is occupied by the nervous 

 la^'er and two-thirds by the muscular layer. The endoderm is 

 rather thicker than the mesoglcea at some points, thinner at others. 

 Stomodcsum. — The stomodseum extends in fulh' expanded 

 specimens about a third of the way to the base of the column. It 

 is much compressed but relativel}' broad, its two ends being nearl}- 

 equidistant from the body- wall. A ciliated groove is present 

 at one end only ; in the middle part of the stomodseum it is of con- 

 siderable size as compared with the remainder of the internal peri- 

 phery. Its cilia are long and stout compared with those of the 

 ectoderm on the external surface of the column. The muscu- 

 lature of the stomodseum resembles that of the body-wall in arrange- 

 ment, but the longitudinal muscles are not so well developed and 

 the circular muscle is very feeble. 



Mesenteries. — In the smaller specimens I have examined there 

 are 24 mesenteries, in the larger specimens 26. The mesenteries 

 are not arranged in pairs, and have no muscle-banners (retractor 

 muscles) ; all are entire. In transverse section each is seen to be 

 considerably swollen in the middle and narrow at either end, i.e., 

 at the inner end, which is joined to the mesentery, and at the outer 

 end, which is joined to the body-wall. 



A band of mesoglcea makes its way into each mesentery from 

 either end, appearing in transverse section as a slender filament ; 

 at its outer extremity each band of mesoglcea supports a few 



