TUN I CAT A. 311 



consideration, Only imagine from ten to twenty individuals, oval in 

 form, more or less flattened, adhering by their dorsal surface to some 

 submarine body, and connected together by their sides, so as to be 

 shaped into the form of a star. " When we excite one of the rays," 

 says Fredol, "a single mollusc contracts itself; when we touch the 

 centre, they all seem to contract themselves (Cuvier). The buccal 

 orifices are at the circumference of the star, but the intestinal ter- 

 minations abut upon a common cavity, which occupies the centre of 

 the star. Here we behold certain animals which eat separately, but 

 which fulfil together as a community very singular functions — a kind 

 of union and communism of which the moral world presents no 

 prototype. With our molluscs we have a score of individuals united. 

 We may consider the entire star as one single animal with many 

 mouths. But, then, we have with it a luxury of organs for the 

 function of intelligence which seeks and chooses, and parsimony of 

 the organ of stupidity, which neither seeks nor chooses." 



While the species of the genus Botryllus are fixed and adherent, 

 those of the genus Pyrosoma, on the contrary, are oceanic. The animal 

 colony which constitutes it floats and balances itself upon the waters, 

 being capable of fully contracting and dilating itself 



The name Pyrosoma has been given to these animals in con- 

 sequence of their brilliant phosphorescent properties. According to 

 the observations of Peron and Lesueur, nothing can exceed the 

 brilliant and dazzling light emitted in the bosom of the ocean by these 

 animals. From the manner in which the colonists dispose themselves, 

 they form occasionally long trains of fire ; but it is a singular fact that 

 this phosphorescence presents the same curious characteristics that 

 are seen in the play of colours caused by the rapid movements of the 

 cilia of the Beroe ; namely, that the colours vary instantaneously, 

 passing with wonderful rapidity from the most intense red to yellow, 

 from golden colour to orange, to green, or to azure blue. Von 

 Humboldt saw a flock of these brilliant living colonies floating by the 

 side of his ship, and projecting circles of light having a radius of not 

 less than twenty inches in diameter. He could see by this light the 

 fishes which followed the ship's track, during many nights, at the 

 depth of from two to three fathoms. 



Bibra, a Brazilian navigator, having caught six Pyrosoma, employed 

 them to light up his cabin. The light produced by these little 

 creatures was so bright, that he could read to one of his friends the 

 description he had written of these his living torches. 



Se\-eral species of Pyrosoma are known ; P. ckgans, about two 

 or three inches in length, inhabits the Mediterranean ; F. giganteu?n 



