Donati, in his Essay on the Natural History of the Adriatic Sea, 

 has made, in some respects, a more minute examination of the struc- 

 ture of two different species of alcyonia than even that of Count 

 Marsilli, and was enabled to ascertain by the aid of a magnifying 

 glass, the peculiar forms assumed by the spines of which these animals 

 are in a great measure composed. Of these we shall soon have occa- 

 sion to speak more particularly. 



The forms in which these animals exist are very numerous ; this de- 

 pending not merely on the number of species, but on the different ir- 

 regular forms which the same species under different circumstances, 

 may assume. Thus Marsilli observes the same alcyonium, which 

 sometimes grows flat, and thus covers large pieces of rocks, is at other 

 times found in a rounded form. 



From the different colours as well as forms which some of the 

 species of these substances possess, they have obtained names expres- 

 sive of their resemblance to certain fruits. Thus the alcyonium lyncu- 

 rium, being of a globose form, of a fibrous internal structure, of a 

 tubercular surface, and of a yellow colour, has been termed the sea- 

 orange : the a. bursa being of a sub-globose form, of a pulpy substance, 

 and of a green colour, has been termed the green sea-orange or sea- 

 apple : the a. cydonium, which is of a roundish form, and of a yellow 

 colour, has been distinguished as the sea-quince: and the a. ficus^ 

 from a very close resemblance to the fig in its form, has been called 

 the sea-fig. 



The sponge is a fixed, flexible animal, very torpid, varying in its 

 figure, and composed either of reticulated fibres, or masses of small 

 spiculae interwoven together, which are clothed with a living gelatinous 

 flesh, full of small mouths or holes on its surface, by which it sucks in 

 and throws out the water. 



The vitality of sponges had been suspected by the ancients, even 

 in the time of Aristotle ; they having perceived "a particular mo- 

 tion ia their substance, as if from shrinking, when they tore them off 



