INSECTS AND THEIR NEAR RELATIVES 21 



Most of our more common millipedes possess stink-glands, which 

 open by pores on a greater or less number of the body-segments. These 

 glands are the only means of defence possessed by millipedes, except the 

 hard cuticula protecting the body. 



The millipedes as a rule are harmless, living in damp places and feed- 

 ing on decaying vegetable matter; but there are a few species that occa- 

 sionally feed upon growing plants. 



Class CHILOPODA 

 The Centipedes or Chilopods 



The members of this class are air-breathing arthropods in which the head 

 is distinct, and the remaining segments of the body form a continuous region. 

 The numerous pairs of legs are not grouped in double pairs, as in the 

 Diplopoda. The antennce are long and many-jointed. 

 The appendages of the first body-segment are jaw- 

 like and function as organs of offense, the poison 

 jaws. The opening of the reproductive organs is in 

 the next to the last segment of the body. 



The animals constituting the class Chilopoda 

 are commonly known as centipedes. They vary 

 to a considerable degree in the form of the body, 

 but in all except a few forms the body-segments 

 are distinct, not grouped in couples as in the dip- 

 lopods (Fig. 41). They are sharply distinguished 

 from the preceding class in the possession of poison- 

 jaws and in having the opening of the reproduc- 

 tive organs at the caudal end of the body. The 

 body is usually flattened. 



Many species of centipedes are venomous. 

 The poison glands open through the appendages 

 of the first body-segment. These organs are leg- 

 like in form and are bent forward so as to act 

 with the mouth -parts. These creatures abound 

 in all parts of the United States ; those which are 

 found in the North are comparatively small, and 

 rarely, if ever, inflict serious injury to man; but 

 the larger species, which occur in the warmer re- 

 gions, are unquestionably venomous. 



The centipedes are predacious, feeding on in- 

 sects; they usually live under stones, logs, and 

 bark. There is one species, the house centipede, 

 Scutigera forceps, which has fifteen pairs of very 

 long legs and which is often present running on 

 the walls of dwelling houses, especially in the 

 warmer regions of the United States. It hunts 

 for flies and other insects and appears to be harm- 

 less to man. It prefers damp situations; in 

 houses it is most frequently found 'in cellars, 

 bathrooms, and closets. Sometimes it becomes 

 very abundant in warm, moist conservatories. 



Fig. 41. — Scutigera forceps. 



