Mr. G. W. Bailey on SUkeous Sjncula in Actiuice. 39 



search were likely to be entangled. On subjecting them to a mi- 

 croscopic observadon I detected a nimiber of veiy interesting and 

 beautiful foi-ms, although the season was not the most favourable. 

 The tirst objects that attracted my attention were great numbers 

 of siliceous spiculse^ precisely simdar to those found fossil in the 

 infusorial strata above referred to ; these I found among the algse, 

 and also more abmidantly in the mud of the docks. These spi- 

 culse resemble those found in some species of Spongia and Tethya, 

 and I beheve that Ehrenberg refers the fossd ones to these genera ; 

 but an obsenation which I made leads me to suspect that some 

 of them, at least, are derived from the exterior rays of Actinia. 

 On examining with a high magnifSing power the rays of a large 

 species of Actinia which had an orange-colom-ed base and olive 

 rays {A. marginata, Lesueur t), I found that the white rays which 

 form the exterior circle appeared to differ from all others, being 

 tilled with spiculte arranged yrvth. great regularity and in count- 

 less numbers, radiating from the axis of each ai-m (see iig. 1, b and 

 c). Each of the spicidse was perforated with a longituchnal cavity, 

 from which was protruded a very long and delicate fibre (see tig. 

 1, a). These spicule resembled so much in then form, perfora- 

 tion, and general appearance, some of the fossil siliceous spicidse 

 aboye referred to, that, like the fossd ones, they must be sihceous. 

 This question I had not the means of deciding, but I hope it will be 

 settled by some of the Boston natiu'ahsts. 

 It is only necessary to burn one of the rays 

 and examine the ashes ; the sihceous spi- 

 cule will of course retain their form after 

 ignition. It would be an interesting fact, 

 if, by means of these spiculte, we could 

 obtain e\idence of the existence of species iL 

 of Actinice dm-ing the epoch of Eocene ter- 

 tiaiy j for who would expect that such soft 

 and perishable creatiu'es coidd leave, for 

 such a length of time, any trace of their 

 existence ? 



The annexed sketches were made merely 

 as memoranda, as I hoped to have further 

 opportrmities for observation. They will 

 serve to indicate the form and position of 

 the spiculse, although they have no pretensions to accuracy. 



EXPLANATION OF FIGURES. 



a One of the spiculag from a white external ray of Actinia inarglnatal 

 showing its longitudinal perforation and the long projecting filament, much 

 magnified. 



b Ideal longitudinal section of a ray to show the manner in which the 

 spicuke are arranged ; at d are seen the vibrilte, and at e the long filaments, 



c Ideal cross section of the ray. 



