G. SPONGIA. 151 



metre; and their diameter from the thickness of a 

 thread to many decimetres. 



We have chosen the forms of the Spongia to cha- 

 racterise the sections, beginning with those of shape- 

 less masses, then taking the more regular cup or cra- 

 ter form, which in succeeding species becomes lobed, 

 gradually assuming the form of branches, till the plant 

 or tree-like sponge appears. 



But these singular and useful beings, to which we 

 are indebted for the sponge, still continue to be un- 

 known; no research has hitherto discovered more 

 than a gelatinous substance, resembling the white of 

 an egg, which surrounds the sponge when undisturbed 

 on its native site, but so fugitive that it runs imme- 

 diately away when taken from its natural element. 



The Spongias are very common between the tropics, 

 less so in the temperate regions, and wholly disappear 

 in the neighbourhood of the Polar circles. 



I shall not in these limited descriptions detail the 

 manner of procuring the sponge, but content myself 

 with reciting two circumstances that prove the esti- 

 mation in which it is held in the countries where it is 

 procured. 



In the island of Nicaria, one of the Grecian Archi- 

 j)elago, the young men are not allowed to marry 

 until they have given proofs of their skill in diving 

 for the sponge : Hasselquist also mentions a small 

 island named Himia, near Rhodes, where the young 

 women cannot marry until they have dived an ap- 

 pointed depth, and procured a certain quantity of 

 sponge. 



