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Art. IX. — Observations and Experiments on the Structure 
and Functions of the Sponge. By Robert Edmond Grant, 
M. D., F. R. S. E., F. L. S., M. W. S., &c. * 
Sponges are aquatic productions ; and as the three known spe- 
cies of fresh-water sponge, the Spongilla pulvinata , Spongilla 
jriabilis , and Spongilla ramosa , are now excluded from the 
genus Spongia by the best authorities, Lamarck, Lamouroux, 
and Cuvier, all the known species of true sponge are inhabitants 
of the ocean. 
Sponges have a very wide geographical distribution. They 
have been met with on the coasts of Norway, New Holland, 
North America, Otaheite, and most of the intervening shores. 
Fabricius found several species on the shores of Greenland, 
and nearly an hundred species were brought by Peron from 
Australasia ; so that this genus has a known distribution over 
nearly 90 degrees of latitude, and within this range they are 
known to abound on the shores of Europe, Asia, Africa, and 
America. 
Their growth and distribution, like those of other animals, 
are influenced by climate. They arrive at greatest perfection 
within the tropics, and become smaller, more rare, and of a 
firmer texture, as we approach the polar circles. Those most 
valued in the arts, the Spongia communis , Spongia lacinulosa , 
and Spongia usitatissima , are inhabitants of the coasts of Ame- 
rica, the Mediterranean, the Red Sea, and the Indian Ocean. 
The small Spongia compressa and the Spongia ciliata thrive 
on the frozen shores of Greenland, beyond the 60th degree of 
north latitude. 
It is not known under what pressure of the ocean these deli- 
cate creatures may live, but they are found equally in places 
covered perpetually by the sea, as in those which it leaves dry 
at every recess of the tide. They adhere to and spread over 
the surface of rocks, Thalassiophytes, and marine animals, and 
are so firmly attached to them, that they cannot be removed 
* Read before the Wernerian Natural History Society, 19th February and 5th 
March 1825. 
