182 



Proceedings of the Royal Irish Academy. 



processes, with tufts of fibres ou them. This applies to the shafts of the 

 tentacles only ; the heads have little or no nmsculature. A vertical section of 

 a portion of oral disc is shown in PL XX, fig. 5, and here some of these 

 short processes may be seen fringing the uiesogloea (which is below) and 



Fio. 2. 



J, nclinopharynx. II, lio<ly-wall. D, dircclive. K, <]iic-tcnlacle. 



'V, nmrginal-tcntAvle. 0, oral diac. F, pcdul disc. 



projectiuf^ into the ectoderm (above). The ectodermal longitudinal muscle- 

 fibres in the body-wall are perfectly clear : I can confirm Hertwig's 

 observation of their existence. I have not given figures of them here, but 

 prefer to do so in jiencil in a later publication. I am doubtful about the 

 existence of ectodermal muscle in the actinophaiynx, however. 



I do not wish to discuss the histology here, except to say that the species 



