228 ARTHROPODA [CH. 



Sub-class B. MYRIAPODA. 



The Myriapoda (Gr. /xvpto?, countless) are characterised by the 

 possession of a head distinct from the rest of the body, bearing 

 antennae, mandibles and one pair of maxillae, followed by a large 

 number of segments bearing simple leg-like appendages. 



Compared with the Crustacea or Insecta the group is a small one, 

 yet it contains some thousands of species which, if we except a few 

 small animals, fall readily into two subdivisions (I) Chilopoda, and 

 (II) Diplopoda. The subdivisions differ markedly from one another, 

 especially in the position of their reproductive openings, which in 

 the Diplopoda are on the third segment behind the head and in the 

 Chilopoda are terminal. For this reason some naturalists break up the 

 sub-class and associate the Chilopoda with the Insecta and the 

 Prototracheata as Opisthogoneata we characterised by the posterior 

 genital opening whilst the Diplopoda with two other orders consisting 

 of minute degenerate forms are classed together as Progoneata. 



Order I. Chilopoda. 



The very active, lithe, chestnut-brown, rather fierce-looking 

 little centipede, Lithobius forfaatus, which is very common during 

 the summer months under the bark of old trees, under leaves and 

 other rubbish, is a good example of the Chilopoda (Gr. x^ LOL ) a 

 thousand) or Centipedes. In the winter it buries itself in the soil. 

 The female lays her eggs from June till August and hastens to 

 cover each with a thin layer of earth; otherwise the egg is seized 

 and devoured by her mate. 



If we examine a little more closely one of these Centipedes we 



shall see that the body is divided into a head followed 

 features! ^7 a verv narrow segment and then by fifteen other 



segments of varying size. The head bears a pair of long 

 antennae, the first appendages, which are constantly waving about. 

 Close behind the point of origin of these antennae lie the eyes. If 

 we turn the animal over and observe the under surface of the head 

 we shall at once see a pair of large vicious-looking claws the 

 poison claws or fifth pair of appendages. The tip of each of these 

 is perforated and, as it strikes the prey, a drop of poison is squeezed 

 out which, soon kills any insect or larva which the Centipede wishes to 

 eat. The bases of these claws are produced into powerful gnathobases 

 by which the prey is held. Although the tips of the poison claws 

 are turned forwards beneath the head, yet these appendages really 

 spring from the first segment of the trunk, which is enlarged and 

 is known as the basilar segment. If we separate with a pair of 



