270 Zoophytes. 



Notes on the nature of the Axis of the Gorgonia verrucosa. 

 By R. Q. Couch, Esq., M.R.C.S.L. 



Whatev^er opinion is entertained regarding the polypidoms of the 

 hydroid, helianthoid, and molluscan zoophytes, no doubt seems to 

 exist among authors but that the stony and homy axes of the asteroid 

 are inorganic. Lamarck, as quoted by Dr. Johnston, says distinctly 

 that they are inorganic, containing neither vessels nor the least por- 

 tion of the body of the polypes, but formed of matter excreted by 

 them, and afterwards thickened, solidified and cleared by affinity ; and 

 to this Dr. Johnston in some measure subscribes. Ellis appears to 

 have entertained an opposite opinion, which he has supported by 

 facts and observations on different species. As the Gorgoniae are the 

 only species of this order found on the Comish coasts, with polypi- 

 doms, the following observations will be confined to them, or rather 

 to the Gorgonia verrucosa, which is very common, and has afforded 

 an extensive means of observation. 



The hard part, or polypidom, of this order, has a new and re- 

 markable position when compared with all the others ; instead of be- 

 ing external and affording both support and shelter to the polypes, 

 it is internal and not immediately connected with them. In many 

 species it is stony, while in others it is horny. In the Gorgonia 

 verrucosa it is horny, solid, fibrous, and extends from the roots to 

 the terminations of all the branches ; it is elastic, of a dark brown 

 or black colour, is sometimes smooth and polished, and at others lon- 

 gitudinally striated, and is traversed by a central white pith. 



The longitudinal rugae are sometimes present, and at others absent, 

 circumstances which do not depend much on the season of the year, 

 but rather on some peculiarities of growth. 



The axis is covered with two membranes, one proper to the fleshy 

 bark, the other to the axis ; but they are not at all times equally well 

 marked. The membrane of the bark lies in close contact with that 

 of the axis : this membrane is fibrous, longitudinally striated, and 

 perforated with numerous oval openings ; these, on one side, commu- 

 nicate with the cells of the polypes by means of the canals of the 

 bark ; on the other, with similar openings in the membrane of the 

 axis. If this membrane be suffered to undergo partial decomposition 

 its texture becomes separated into cellular-looking bodies, very simi- 

 lar to w^hat Ellis has figured in his *Essay on Corallines,' pi. 38, A 3, 

 as belonging to the Gorgonia placomus. They however slightly dif- 

 fer, as they probably do in each species. In the Gorgonia verrucosa 



