i8 OUR INSECT FRIENDS AND FOES 



falces or chelicerae, and functioning as the true 

 mandibles, which are absent. Behind these are 

 the large pincer-claws, or pedipalpi, which give 

 the Scorpion a superficial resemblance to a 

 crayfish, and following upon these great claw- 

 like limbs are four pairs of walking legs. 



The Spiders differ from the Scorpions in having 

 the abdomen short, rounded, and segmented, while 

 the falces or chelicerae are provided with poison 

 glands, the ducts of which open at the extremities ; 

 and the pedipalpi are simple. At the extremity 

 of the abdomen is the spinning organ, consisting 

 of four or six elevations, the spinnerets, on the 

 surfaces of which the numerous ducts of the 

 spinning glands open. 



No distinction into cephalothoracic and 

 abdominal regions is recognizable in the Mites 

 and Ticks, although there exist the same series 

 of paired appendages as in the Scorpions and 

 Spiders. The study of the life-history and habits 

 of the Ticks is of great economic importance, as 

 many are now known to be the transmitting 

 agents of various diseases to man, and to cattle, 

 sheep, horses, dogs, and fowls. The Ticks pass 

 through an incomplete metamorphosis, and it 

 is interesting to note that while in some species 

 it is the males who go a-courting, in other species 

 it is the females who fight for the possession 

 of the males. The extraordinary part which the 

 Ticks play as carriers of disease will be dealt with 

 in Chapter IX. 



Insects are the most ubiquitous of animals, to 

 be met with practically in every part of the 

 habitable world, from within the Arctic Circle to 



