5iOOPHYTES. 5§l 



no distinct apparatus for respiration, and no sense but that 

 of feeling and perhaps that of tasting. This is not true, 

 however, without exception ; for, in some instances, traces 

 ' of a nervous system, of a circulation, and of respiratory or- 

 gans, may be detected, as in the sea-urchin, the common 

 star-fish, and the sea-egg. These Zoophytes are the most 

 perfect in their structure, and are endowed with a curious 

 set of organs for the purpose of motion. Their shells are 

 pierced with a large number of holes, regularly arranged, 

 through which project the feet of the animal, or rather the 

 instruments answering the purpose of feet. These are little 

 hollow cylinders, filled with a liquid, and terminating in a 

 kind of knob, which is also hollow. By forcing the liquid 

 into these cylinders, or by exhausting it from them, the ani- 

 mal can either lengthen or shorten them. The knob, when 

 exhausted, is drawn into a cup-like form, and thus may be 

 firmly fixed to whatever object it is applied, like a cupping- 

 glass ; and when the liquid is again thrown into it, it is 

 again loosened. 



Pol'ypes have a hollow, cylindrical, or conical body, with 

 one extremity open which serves for their mouth, and is sur- 

 rounded by a number of orgaps, (icntacula) by which they 

 seize their prey. Many of them have been celebrated on 

 account of the fact, that when one is divided into several 

 pieces, each piece becomes a distinct animal, perfect in all 

 its parts. The immense beds of coral and the diflferent 

 kinds of sponge, are nothing but the habitations of infinite 

 numbers of these little animals, and are produced by their 

 labour. Corals grow in such quantities, and to such heights 

 in some seas, as to create islands. The Friendly Islands, 

 in the Pacific Ocean, were thus raised by corals from the 

 depth of that sea. Ships have often been lost by striking 

 on coral-rocks. 



Questions. — 1. What is said of the former and present application of 

 the term Vermes ? 2. What is said of the structure of Vermes ? 3. Of 

 the circulation of their blood and of their respiration? 4. Of their in- 

 struments of motion, and their habitations ? 5. Describe the medici- 

 nal Leech. 6. What is said of the general structure of Zoophytes? 

 7. Describe the organs of motion in the most perfect Zoophytes. 8. 

 What is the structure of Polypes ? 9. For what celebrated ? 10. How 

 are corals and sponge produced ? 11. What is said of the growth of 

 corals in some seas ? [Note. To the class of Zoophytes belong In- 

 testinnl worms, sea-nettles, or sea-anem'ones, Medusae, or sunfish, an<J 



