566 SYDNEY J. HICKSON. 



numerous and close folds into which the stomodseum is thrown, 

 but after a careful examination of a number of sections, the 

 characteristic long cilia and the thickened epithelium on the 

 ventral side of the stomodeeum were found (figs. 8 and 9, Si), 

 and I have no doubt that when the polype is fully expanded a 

 siphonoglyphe is present of the characteristic shape and 

 nature. 



The stomodseum is held in position by eight mesenteries 

 which bear the powerful retractor muscles (figs. 8 and 9, r. 

 m.). The muscular bundles exhibit the same arrangement 

 as in other Alcyonarians (von Koch 10, fig. 6), being 

 placed in all cases on the side of the mesentery which faces 

 the ventral side of the polype. The protractor muscles (fig. 

 8, pm) are exceedingly delicate structures, consisting of but 

 a few parallel fibres situated on the parts of the mesen- 

 teries in front of the stomodseum. The remarkable difference 

 in size between the retractor and protractor muscles may be 

 accounted for by the fact that strong muscles are required to 

 suddenly retract the polypes, when irritated, and to drive out 

 the water contained in the body-cavity at the same time, 

 whereas the expansion of the polypes is always in Alcyonarians 

 a very slow process and is probably aided, to a considerable 

 extent, by the ciliary action filling all the cavities of the polype 

 with water and thus helping to drive the polype out of the 

 tube. 



The ova are attached to the sides of the dorsal and dorso- 

 lateral mesenteries immediately below the termination of the 

 stomodreum (fig. 8, ov.). Each ovum is enclosed in a capsule 

 and attached by a short stalk to the side of the mesentery. 1 

 have never seen the stalk of an ovum attached to the mesen- 

 terial filament as von Koch (10) describes it to be, nor can I 

 find more than exceptionally that an ovum is attached either 

 to the ventral or ventro-lateral mesenteries (conf. von Koch 10, 

 fig. 7). 



There are only two mesenterial filaments, the dorsal ones, as 

 in the siphonozooids of Pennatulidao (Kolliker) and Sarco- 

 phyton (Moseley), and these extend for a considerable distance 



