OF INVERTEBRATE ANIMALS. 403 



or, urllike almost all others, they are unable to move from place to place. The 

 form of their tentacula will be seen in Fig. 4. Every animal body must possess 

 some kind of solid basis or framework, in order to form a support for its softer 

 parts, called its skeleton, and although in some animals this is of a very slight 

 nature, in others we have a remarkably strong and complicated apparatus for 

 this purpose. In this class of animals the skeleton is very simple, being nothing 

 more than a large branched mass of inorganic matter, wbich either covers its soft 

 parts or supports them, and varies exceedingly in texture, shape, and size, accord- 

 ing to the requirements of each particular kind of animal. The skeletons or 

 organs of support of these animals are known as objects of ornament, by the 

 names of Corals, Madrepores, Millepores, &c. The size to which these attain is 

 sometimes very great ; each of these masses must not, however, be regarded 

 as the skeleton of a single animal, but rather as the work of a community. 

 Although it is very difficult to say whether we ought to consider each polype 

 as an entire animal, yet on account of the facility with which they are enabled 

 to maintain an independent existence, the collected masses have generally been 

 considered as an aggregate of animals. These animals generally inhabit the 

 depths of the ocean, where the branched forms of their organs of support, and the 

 varied colours and shapes of their tentacula, give them the appearance of a forest 

 of trees. In fact it is not yet a hundred years since naturalists mistook many 

 of these curious animals for plants ; and even now they bear a name, zoophytes, 

 which would indicate that they belong both to the animal and vegetable king- 

 doms. These animals exist in such enormous numbers at the bottom of some 

 seas, that the collections of matter forming their skeletons are often brought almost 

 to the surface of the ocean, where they form formidable reefs that frequently seal 

 the fate of the unwary mariner who navigates his bark upon their unseen 

 summits. But more than this, these reefs are sometimes thrown above the level 

 of the sea by volcanic or other changes, and thus these animals have been supposed 

 to be the chief agents employed by the Creator in forming those delightful islands 

 scattered so abundantly throughout the Southern Sea. 



I cannot here enter into any particulars concerning all the varied forms these 

 creatures assume, nor indeed of any of the other classes of animals to which I 

 allude, but there is one form which, as it is so well known, I cannot but refer to. 

 I allude to the Common Sponge. This is not a vegetable production, as often 

 supposed, but is the organ of support or skeleton of an animal belonging to this 

 class. It differs from those I have just mentioned in not possessing tentacula, 

 and may indeed be considered as the simplest form of animal life. In all Sponges 

 we find several pores or holes, the smaller of which are destined for the purpose 

 of receiving the sea- water in which they live, which, being filled with animalcules, 

 the Sponge appropriates them as food ; and the water, thus deprived of its 



