PHYLUM ARTHROPODA 



379 



tributed over the body, and the sense of touch is quite delicate. 

 There are four pairs of lung books opening by means of stigmata 

 (Fig. 318, B) on the 

 under surface of ab- 

 dominal segments 

 III-VI. 



The mating activi- 

 ties of scorpions are 

 very curious, and 

 include a sort of 

 promenade (Fig. 

 319). Scorpions are 

 viviparous. The 

 young ride about upon the back of the female for about a week, 

 and then shift for themselves. They reach maturity in about 

 five years. 



Order 3. Phalangidea. — Harvestmen or Daddy-long- 

 legs. — The harvestmen may be distinguished from spiders by 



Fig. 319. — The "promenade a deux" 

 scorpion, Buthus occitanus. (From the Cambridge 

 Natural History, after Fabre.) 



Fig. 320. — Order Phalangidea. Harvestman, Phalangium opilio, male. 

 (From Sedgwick's Zoology.) 



their extremely long legs (Fig. 320), the absence of a waist, and 

 their segmented abdomen. They are able to run rapidly over 

 leaves and grass. Their food consists of small living insects. 



Order 4. Acarina. — Mites and Ticks. — These are minute 

 arachnids without any external signs of segmentation. Many of 

 them are parasitic and often cause serious diseases. 



