ALCYONELLA. 113 



Various specimens, under great variety of aspect, were collected in 

 the end of August, the diversity of appearance resulting, it might be, at 

 least in part, from the diversity of the substances invested. Among these 

 was chiefly wood as before, apparently the peculiar and favourite site of 

 the Alcyonella. But it also covered the slender stalks of the grass grow- 

 ing at the edge of the water, and there completely immerged. The ra- 

 dicles of those trees bordering the pond, which, penetrating the soil, reach- 

 ed the water, together with almost every ligneous fragment which had lain 

 amidst the element any considerable period, bore the same product ad- 

 vancing vigorously. 



A long branch of the larch, even one of its cones, was invested, and 

 the fallen leaves of other trees, accidentally in contact, were firmly united 

 by the overspreading vegetation of the zoophyte. Twigs, such as that re- 

 presented, Plate XXX. fig. 5, were completely invested by it. 



With exception of the grass, it rather seemed to me that those sub- 

 stances serving as the site of the Alcyonella had been matured by age, 

 and adapted for it by approaching decay ; and that they were thus rendered 

 more favourable for its reception. 



Sometimes an hundred spots appeared on a large surface, or one oc- 

 cupying smaller space was totally overspread. Cylindrical portions, of 

 more limited dimensions, were wholly encircled, probably by the edges 

 from each side meeting in their diffusion. While this is advancing, the 

 Alcyonella diffuses at both ends, upwards and downwards, as may be con- 

 cluded, supposing the position of the investing cylinder to be perpendicu- 

 lar. Thence results the encircling stratum. Something analogous, but 

 on a larger scale, is evident in the snowy white Alcyonium digitatum or 

 Lobularia, when investing the dingy tube of the Amphitrite. In like man- 

 ner, and under corresponding resemblance to the same product, some parts 

 of the Alcyonella thicken much more than belongs to a single stratum, 

 but likewise rising in hemispherical or conical protuberances. How this 

 ensues is far from obvious. If by superposition, the destruction of the 

 hydra? composing the lower, earlier, or original strata, is the necessary con- 

 sequence. We might ask, does it abridge the life of these animals, of 

 which observation seems to sanction the longer promise ? — Figs. 6, 7. 

 VOL. II. v 



