I 



M. Valenciennes on Me Gorgonidse. 1*79 



the Gorgonice, and upon the form and arrangement of tbe cells in 

 the friable envelope of the branches, to which they give the name 

 of cortex. M. Milne-Edwards has ascertained that this enve- 

 lope, when examined upon living animals, is composed of a sort 

 of contractile parenchyma, which is rendered arenaceous by the 

 quantity of calcareous molecules contained in it. His extended 

 knowledge of the organization of the polypes, has shown him 

 the relations which exist between the envelope and the axis ; and 

 in order to render his idea more intelligible he has given the 

 name of sclerenchyrna to the external portion from which the 

 extensible bodies of the polypes issue, and of sclerobase to the 

 concealed portion, which he still regarded as composed of a 

 horny matter. 



It appears from what I have just stated, that a Gorgonia is a 

 body formed by the union of numerous polypes upon a common 

 body, enveloped by an arenaceous sclerenchyma surrounding 

 another dendroid secretion, the sclerobase ; just as a Veretillum 

 is composed of numerous polypes protruded from a soft fleshy 

 sclerenchyma. The sclerenchyma of the Gorgonidm contains 

 numerous sclerites. These, which are often microscopic, but are 

 sometimes as much as 2 millimetres in length and consequently 

 visible to the naked eye, occur in all the genera of this family. 

 The following are some of the principal forms : — 



1. The corpuscles have two small circles of tubercles at a 

 distance from one another on a short axis ; the tuberculate ex- 

 tremities resemble a small branch of cauliflower. These occur 

 in Junceella juncea, surculus and elongata, Gorgonella sulcifertty 

 Ctenocella pectinata, Rhipidigorgia umhraculum^ cribrum, arenata^ 

 &c., and in the qpmmon coral of the Mediterranean. 



2. Other sclerites are fusiform, with four or six circlets of 

 tubercles. These occur in Pterogorgia simplex, Plexaura virgea 

 and petejphizans, Phycogorgia foliata, Rhipidigorgia reticulum, 

 Gorgonella cauliculus, &c. 



3. A third form is that of the clubbed sclerites, in which a 

 single extremity is dilated, and furnished with ridges, like some 

 ancient maces. These are found in Gorgonia crinita, papillifera 

 and placomus, Gorgonella betulina and ceratophyta, Plexaura ho- 

 momalla, pensiliSj parvula, &c. 



4. A fourth and new form is seen in the muricated sclerites 

 with four or several points, and entirely covered with spines, 

 which occur in Plexaura aurantiaca, Plexaurella dichotoma, Gor-- 

 gonia vcrmiculata, &c. 



5. A fifth form consists of larger or smaller scales, more or 

 less covered with small spines. These are found in Cricocella 

 verticillaris and plumatilis, Primnon lepadifera and antarctica, Gor- 

 gonia fungif era, &c. 



