378 



COLLEGE ZOOLOGY 



is often stated, to sting itself to death, since its poison has no 

 effect upon its own body. 



The scorpion's body (Fig. 318) is more obviously segmented 

 than that of most of the other arachnids. There is a cephalo- 

 thorax (prosoma) , and an abdomen of two parts a thick an- 

 terior portion (mesosoma), and a slender tail (metasoma) which 



Provoma 



A/eaosoma 



B 



Metasomo 



ctcttleus 



FIG. 318. Scorpion, Bulhus occitanus. A, dorsal view. B, ventral view. 

 (From the Cambridge Natural History, after Kraepelin.) 



is held over the back when the animal walks. The dorsal shield 

 of the cephalothorax bears a pair of median eyes and three lateral 

 eyes on each side. The sense of sight is, however, poorly de- 

 veloped. On the ventral surface of the second abdominal seg- 

 ment are two comb-like appendages called pectines (Fig. 318, B) ; 

 these are probably special tactile organs. Tactile hairs are dis- 



