GO CLASSIFICATION OF THE ANIMAL KINGDOM. 



their first appearance, possess the power of moving about by means of 

 cilia, but these drop off" on the animals becoming fixed to any suitable 

 substance. 



The next class, Polyps, is a very interesting one; the lowest in order, 

 the Mushroom Corals, much resemble the Sponges, onlj-, instead of a horny 

 elastic substance, they secrete a stony calcareous skeleton. When alive, 

 these corals are covered with gelatine, which is endowed with a slight 

 power of sensibility, for it contracts if rudely assailed. These animals are 

 not attached, and, as the motions of the sea would easily overturn them, 

 in order to keep the right side uppermost, they are provided with a 

 singular apparatus of air-vessels. Their means of growth is not well under- 

 stood, |no organs of vitality being as yet discovered, but the gelatinous 

 covering, it is presumed, in some way or other absorbs materials of support 

 from the surrounding water; so that, if superior to the former genus in 

 the nature of their secretion and sensitive powers, yet they would certainly 

 seem to be inferior to them in their means of obtaining food by the 

 formation of currents in the water. Their reproduction is by the devel- 

 opment of sprouts or gemmules, which, in process of time, become 

 detached. 



The Hydras, or Fresh-water Polyps, are next described. These animals 

 are common in our ponds and ditches, and resemble little transparent 

 lumps of gelatine; they have the power of motion, can appreciate the 

 presence of light, and possess a simple bag in the nature of a stomach, 

 with digestive powers of a very enviable description. Their mode of 

 catching prey is by means of a variable number of tentacula spread round 

 the mouth; and their means of reproduction is by the growth of gemmae 

 or sprouts, and by mechanical division or incision. Next come the cortical 

 compound Polyps, gregarious animals, some of which secrete a soft central 

 mass; a good example of which we have in our coasts in the Alcyonium 

 digitatum, or "Dead man's fingers," as they are usually called, and others 

 which produce a hard calcareous matter, as the Corallidce, or Corals, etc. 

 The Separate Polyps resemble somewhat the Hydrce, but have invariably 

 eight tentacula. The stomach of these animals terminates in a tube, which 

 extends into the common mass of gelatine, to which it probably conveys 

 nourishment; there is in fact an individuality and community of nutrition 

 in each Polyp. In their means of reproduction they are decidedly higher 

 than anything we have yet met with, as each Polyp possesses an ovary, in 

 which germs are developed. 



The Madreporidce and Corallidce are next described — animals which, though 

 exceedingly minute, and composed of a soft gelatinous substance, by the 

 deposition of their skeletons, become a mighty agency in the hands of 

 God for the production of new land in the tropical seas. In one tribe of 



