LECTURE XII. 211 



-that can be imagined as to shape, but still preserv- 

 ing its particularity of surface. 



Some of the Madrepores bear an appearance 

 so perfectly similar to that of some kind of Mush- 

 room, that they have often been considered as pe- 

 trified Mushrooms. The Madrepores in general 

 as well as the other larger Corals, are chiefly found 

 about the coasts of the Indian islands, where they 

 are so numerous as to form vast rocks, their animals 

 seeming to carry on their work by a kind of instinct, 

 continuing to grow in such a manner as to encircle 

 a vast body of water, so as to form a calm or smooth 

 bay. Within the tropical seas, according to the 

 learned Dr. Reinhold Forster, in his ingenious dis- 

 sertation on India, there are numerous small 

 islands, but little elevated above the surface of the 

 sea. All these are the work of marine Zoophyte 

 Vermes, which raise on all sides their calcarious 

 matter, from which at length are formed rocks 

 and stony shallows, very dangerous to navigators. 

 Easterly winds being most prevalent in these seas, 

 the animals, as if actuated by instinct, endeavour 

 to exclude the waves driv ; en by the winds, by 

 means of their stupendous works 3 and therefore, 

 carrying on their habitations, they extend them 



