,51 



union is found not to rxist only at the neshy cruRt, or at the 

 edges of the horny axis, but throu2;hout the extent of the 

 opposing snrfaces. In some cases the union has taken place 

 as soon as the branches came in contact ; in others, and by far 

 the most numerous, the axis has been rubbed half through 

 and then united. On one occasion one branch had become 

 interweaved with three others, and where they touched they 

 became united in the crusi and surfaces of the worn axis. So 

 tliat the axis must, I think, be allowed to posses a vital power, 

 a power which enables it to form new branches in its own 

 texture and to unite any points wliich may have been made 

 bare by the friction of others. If the axis be inorganic and 

 exfravascular, these phenomena are to me inexplicable. 



The axis is frequently denuded for a considerable extent, 

 either from accident or the incrustation of Corallines. Prom 

 the soft and uneven nature of the crust it is very liable to be 

 infested with parasitic animals, such as the Cellepora piunicosa, 

 many species of Sertu/aria and Tnbulipora ; different kinds 

 of Lepades of which the L. Scalpelium seems to prefer it to 

 any other situation. 



The Gorgoniadce are always firmly rooted to the rocks and 

 stones on which they grow; and the crust and axis both 

 extend themselves over the surface and produce a firmer 

 rooting. The pith does not extend into the root. The layers 

 of which the expanded root is formed, are more membra- 

 naceous, more loosely united, and not so solid as the layers 

 composing the trunk aud branches. 



The second division, destitute of an axis, comprises the 

 Alcyonidce of which there are three recognized British species, 

 belonging to two genera. One of which, the Cydonium 

 Mulleri of Fleming and Johnston, has since been removed 

 from the Asteriod Zoophytes, and placed among the sponges 

 of the genus Geodia. In my paper on the sponges of Corn- 

 wall, published in the transactions of the Falmouth Poly- 

 technic Society,* I expressed an opinion that the Cydonium 

 would occupy a place between the true and a-polypus zoophy- 

 tes. Such an opinion was formed from the inspection of 

 only one specimen and was therefore liable to error; but Dr. 

 Johnston in his valuable work on British Sponges is of the 

 same opinion ; so that the native species of this division 

 amount now only to two. Under the Alcyonium digitatuni 

 two species have I think been confounded but will here be 

 found separated as Al. sanguineum, from its colour. 



The form of tlie Alcyonium is liable to great variations, 

 which are chiefly dependent on the age of the specimen ; 



* Report for 1842. 



