. Annals of natural history. Natural history; Botany; Zoology; Geology. Mr. G. W. Bailey on Siliceous Spicula in Actiniae. 39 search were likely to be entangled. On subjecting them to a mi- croscopic observation I detected a number of very interesting and beautiful forms, although the season was not the most favourable. The first objects that attracted my attention were great numbers of siliceous spicula3, precisely similar to those found fossil in the infusorial strata above referred to; these I found among the algse, and also more abundantly in the mud of the docks. These spi- culse resemble
. Annals of natural history. Natural history; Botany; Zoology; Geology. Mr. G. W. Bailey on Siliceous Spicula in Actiniae. 39 search were likely to be entangled. On subjecting them to a mi- croscopic observation I detected a number of very interesting and beautiful forms, although the season was not the most favourable. The first objects that attracted my attention were great numbers of siliceous spicula3, precisely similar to those found fossil in the infusorial strata above referred to; these I found among the algse, and also more abundantly in the mud of the docks. These spi- culse resemble those found in some species of Spongia and Tethya, and I believe that Ehrenberg refers the fossil ones to these genera; but an observation 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 magnifying power the rays of a large species of Actinia which had an orange-coloured base and olive rays {A. marginata, Lesueur ?), I found that the white rays which form the exterior circle appeared to differ from all others, being filled with spiculse arranged with great regularity and in count- less nmnbers, radiating from the axis of each arm (see fig. 1, b and c). Each of the spiculse was perforated with a longitudinal cavity, from which was protruded a very long and delicate fibre (see fig. ], a). These spiculse resembled so much in their form, perfora- tion, and general appearance, some of the fossil siliceous spicules above refeiTcd to, that, like the fossil ones, they must be siliceous. This question I had not the means of deciding, but I hope it will be settled by some of the Boston naturahsts. It is only necessary to burn one of the rays and examine the ashes; the siliceous spi- culse will of com-se retain their form after ignition. It would be an interesting fact, if, by means of these spiculse, we could obtain evidence of the existence of species d of Actinice dm^ing the epoch of Eocene ter- tiar
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