34 ZOOPHYTES. 



Alcyonidium parasiticum here — premising that by the generic Alcyoni- 

 dium, is merely to be understood a product related to the Alcyonium. 



Dr Fleming proposes that the present species shall be annexed, pro- 

 visionally, to the genus Alcyonium of modern authors. Dr Johnston 

 seems to doubt whether that is its particular place. 



I shall not presume to dissent so far from these two accomplished natu- 

 ralists, as to infringe on the name recognized by them. But it appears 

 to me, that the difficulties attending the position of the product, origi- 

 nate in the nature of the polyparium, and the fashion of its growth. 

 1. The Alcyonium, at least any falling under my observation, is not an in- 

 vesting or spreading zoophyte. 2. It always rises independently, in an 

 erect or vertical direction, or in some cases, the same is inverted ; and it 

 has a tendency to subordinate ramification. 3. The polyparium is of a 

 consistent, subgelatinous matter. 4. The suceeding generation over- 

 whelms that preceding it. 



On the other hand, the Alcyonidium parasiticum is truly what its 

 name expresses. It never grows erect from its own foundation ; it is al- 

 ways an investing zoophyte, as the bark covers the wood beneath ; or it 

 may form a thin stratum over some portion of an old shell, a fact whereof 

 I cannot speak as decisively as I could desire. 



In its perfect state, the Alcyonidium is to external appearance, a 

 meagre shrub, growing vertically, all the parts irregularly cylindrical, with 

 obtuse extremities: The whole of spongy aspect, and dark hair-brown 

 colour. 



By this, the inexperienced observer may be completely deluded, for 

 he has nothing before him but a stratum of parasite matter, investing 

 some other substance by a thin covering. It follows the whole lines and 

 curvings of the surface, and at length reaching the extremities, it extends 

 about a line beyond them. But now, the investing complete, it bears the 

 narrowest resemblance to an erect, or other independent production of 

 vegetable formation. — Plate X., figs. 1, 2. 



A long time seems to be occupied by its growth, which is very gra- 

 dual, portions of the substance invested, a coralline, for example, fig. 1. 

 remaining free at the extremity. 



