180 M.Valenciennes on the Gorgonidoe. 



These sclerites exhibit the most agreeable colours : some are 

 white and transparent like a fine crystal of Iceland spar, others 

 violet like amethyst, others red or yellow. Their transparency 

 has led to the supposition that these corpuscles were composed 

 of small crystals, but M. Senarmont after the examination of 

 several sorts has been unable to recognize any crystalline form 

 in them, and does not hesitate to say that they are not crystals. 

 Their similarity in such different species of Gorgonidce proves 

 that these sclerites cannot be employed in characterizing the 

 genera, as has been supposed by some very excellent zoologists : 

 they can only be taken into account in the diagnosis of the 

 species. 



The sclerenchyma thus formed is perforated with cells, which 

 sometimes project from the surface like small warts, whilst in 

 other species they are pierced as though with the point of a 

 needle. These cells are sometimes margined with a small ex- 

 pansion which may be called a lip ; other species have the cells 

 surrounded by small scales. 



A second organ, the study of which is of great importance, is 

 the axis or sclerobase. A fact first established by my researches 

 with the aid of M. Fremy, is, that this axis, notwithstanding its 

 external appearance, does not consist of horn like that of the 

 claws and hoofs of the Mammalia or the horns of Ruminants. It 

 is a substance sui generis, which however approaches more closely 

 to horn than to the chitine of the articulated animals. It is 

 insoluble even in hot solution of potash, brought to the greatest 

 possible concentration by boiling. Some species give up a por- 

 tion of their colouring matter to muriatic acid; others yield 

 nothing. I have met with some sclerobases wjiich became soft, 

 and even began to dissolve in this acid. It is therefore a new 

 substance peculiar to the Gorgonid(B, like the conchyoline of the 

 Mollusca, of which the shells of the genus Pinna furnish such 

 large and fine specimens. I think we may designate this sub- 

 stance by the name of corneine, on account of its resemblance to 

 the material of the hoofs and nails of the Mammalia. The ana- 

 lyses made by M. Fremy prove that it is isomeric with horn. 



The sclerobase does not consist of corneine alone in all the 

 species of Gorgonidce. In a great number of species the axis 

 contains a considerable quantity of carbonate of lime. Several 

 species possess an axis which gives a very brisk effervescence 

 with muriatic acid. This physiological fact is very important in 

 the classification of the Gorgonidce, and not less so in explaining 

 the way in which the membranes of the polypes assist in the 

 formation of the sclerenchyma and sclerobase. Those species 

 with a calcareous sclerobase, which I unite under the name of 

 Gorgonellacea, have the body prolonged into the common sarcoid 



