12 PREFACE. 



being made up of successive rounded rings or seg- 

 ments with a fold between them. They belong, in 

 fact, to two different types of structure ; the cotton- 

 worm being an Arthropod or jointed-foot insect, 

 and the rain-worm belonging to the true footless 

 worms or Vermes. 



Counting backwards from the head, we find that 

 on the 6th, 7th, 8th, and 9th segments of the body 

 of the cotton- worm there are pairs of short fiesliy 

 projections, which are not jointed, but are used by 

 the cotton-worm for progression. The pair on the 

 6th segment are not used, and there are projections 

 of the skin on the 10th segment also, showing a 

 distribution of these fleshy processes or false legs 

 along the line of the hinder part of the body, with- 

 out reference to their usefulness to the animal, and 

 in an imperfect condition of development. The 

 last segment of the body is provided with a pair of 

 these fleshy false legs for grasping the leaf and 

 maintaining the position of the animal while feed- 

 insc. When we come to examine the anterior end 

 or head of the cotton-worm, we find it made up 

 of a harder covering above, and beneath of pairs 

 of jointed appendages, the most prominent of which 

 are the cutting-jaws or mandibles, which perform 

 the office of supplying food by tearing off the leaf 

 of the cotton-plant. These jointed appendages to 

 the head are similar in structure to the jointed feet 

 of the animal, though they serve a different purpose 

 in its economy ; they are here head organs ; so 

 that we now see that there are three distinct regions 

 of the body in the cotton-worm characterized by 



