458 Naturai'Histdficui Collections, 



convenient place to take up its abode. And if the species be not hennaphrodite, 

 the male must have to seek for and fecundate the female. However, we hear of 

 similar changes which take place in another parasite of the family of lemeeie, dis> 

 covered by Dr. Sussiray of Havre. The young have feet proper for swimming, 

 and with age they change their form and become immoveable. Every onB 

 knows that something of the same kind takes place in the cocci.* 



Observations on Liihophytes From the examination made by celebrated na- 

 turalists of the common red coral, the gorgonia, alcyonia, and a great number of 

 other corals, we know that the stony or horny axes are nothing hut the common 

 skeletons of the compound animals, — that they are covered, during life, with a sen- 

 sible incrustation or envelope ; and that the hydras or polypes, which expand over 

 different parts of their crust, and which have been for a long time taken for the 

 flowers of the coral, are individual animals, which, in their assemblage form the 

 common animals — which have a common nutrition, and whose sensations, even 

 to a certain degree, communicate throughout the whole. It had been concluded 

 that the individual animals become, in all lithophytes, like the hydras ; but it is 

 not entirely so. The observations of M. Lesueur, and of iWM. Eisenhardt and 

 Chamisso have shown that the animals of many lameUated madrepores resemble 

 the actiniae as much as the hydree. 



MM. Quoy and Gaymard, the authors of the geological part of the voyage 

 of M. Freycinet, a collection full of the most interesting observations on the ani- 

 mal kingdom, have inserted therein some facts relative to the lithophytes, which 

 they had previously communicated to the Academy, and which add to our know- 

 ledge on this curious subject. The fungice, of the subdivision of the madre- 

 pores composed of great strong plates which converge to a hollow centre, or to- 

 wards a central furrow, are amply enveloped with a red membranous animal 

 crust, plaited in folds, thicker towards the centre, or median furrow, and which 

 cannot be developed without breaking them. It appears, however, that in the" 

 centre there is a cavity which is the organ of digestion, and that when the disk 

 is elongated and the centre becomes a furrow, there are sometimes two or three 

 of these cavities. The caryophyllia;, another section of the madrepores, whose 

 branches are terminated by an orbicular star, have this star filled with an animal 

 Substance, which produces long cylindrical tubes fixed in the anfractuosities of 

 the lamina, and whose free extremity is marked with a number of little points, 

 MM. Quoy and Gymard regard those cylindrical productions as the animals of 

 this lithophyte ; M3I, Eisenhardt and Chamisso, who have also observed them, 

 take them, on the contrary, for the tenticula of an animal, of which there will be 

 one in every star, but whose central mouth they confess they have not seen. Ad- 

 ditional observation will be requisite to establish their opinion on this subject. 



These learned travellers have made a particular study of that lithophyte com. 

 posed of parallel tubes, which is known under the name of Tubipora musica. 

 They had been long referred to the class of articulated worms ; but M. Cuvier 

 determined them to be hydras. Their colour is of a beautiful green, their strong 

 envelope of as beautiful a red ; each of them is contained in a membranous sac, 

 whose margins are reflected over those of the tube in which it is inclosed, and the 

 hydra can retract and hide itself altogether, oi develope itself and push out tenta- 

 cula to the number of eight. In the bottom of the sac are filaments filled with 

 granular bodies, which appear to be the ova. The strong tube is elongated by 

 degrees ; and from space to space it dilates in a horizontal margin which, uniting 

 itself to those of the adjoining tubes, forms septa by which the whole of the tubes 

 ar e joined. 



{To be continimJ.) 



• On this subject, vide Thompson's Zoological researches,—" metamor- 

 phoses of the Crustacea." — Ed. 



