ORDER I. INTESTINA. 315 



Worms include five orders, viz. 



^ INTESTINA ; or animals perfectly naked, and without 

 any kind of limbs. 



2. MOLLUSCS ; simple and naked animals ; but bra- 

 chiated, or furnished with a species of limbs. 



3. TESTACEA ; animals having soft simple bodies, but 

 covered with a coat of a calcareous nature. 



4. LYTHOPHITA and ZOOPHITA; animals furnished with 

 a kind of flowers, and having a vegetating root and stem. 



5. INFUSORIA ; very small simple microscopic animals. * 

 This class, like the preceding, must be here confined to 



a brief survey. It is the professed object of this work to 

 conduct the student only to the threshold of the spacious 

 temple of animated nature : rather to stimulate research 

 by a short comprehensive view of well-known facts, than 

 to explore minutely the vast field of animation. 



ORDER I. INTESTINA. 



THE characteristics of this order are, that the animals are 

 perfectly naked, and without any kind of limbs. There are 

 twenty-one genera ; in which the most remarkable species 

 are the various intestinal worms of men and other ani- 

 mals, the earth-worm, and the leech. A description of 

 the common earth-worm may suffice to give a general idea 

 of the whole. 



This creature has a spiral muscle running round the 

 whole body, from the head to the tail, by means of which 

 it performs its progressive motion : alternately contracting 

 and dilating itself; and easily keeping the ground which 

 it has gained, by means of the slime appertaining to the 

 fore-part of its body. 



Being formed for a life of obscurity, the worm is wisely 



* These definitions should be committed to memory. 



T> Q 



