ARTHROPODA 



211 



1880; Graber, 1880 ; Caesar, 1913 ; Const ant ineanu, 1930). In some 

 types, such as Pauropus, which live in moist debris in the woods and 

 forests, eyes are lacking. 



ARACHNIDA 



The ARACHNIDS form a large and loosely associated group which 

 includes scorpions, king-crabs, spiders, pseudo-scorpions, whip-tailed 

 scorpions, harvest-men, jerrymanders, mites and ticks. With the 

 single exception of the king-crab they do not possess conii^ound eyes 



Fig. 211. — The Kikg-crab, Limvlus polypbeml's. 

 A .simple ej'e, S, is seen as a dark spot situated on either side of the median 

 spine. The two compound eyes, C, are situated on the external aspect of 

 each of the first lateral spines (specimen from Natural Historj^ Museum, 

 London). 



but all are provided with ocelli sometimes of considerable size and 

 complexity. 



SCORPIONS (scorpionidea), venomous animals up to 8 in. in length 

 with a long stinging tail, are restricted to warm countries ; in habit 

 they are essentially solitary and nocturnal, being active during the 

 night and spending the day lurkmg under stones or in crevices. They 

 are provided with a pair of large median eyes situated about the middle 

 of the cephalothorax, and 2 to 6 pairs of lateral ocelli placed on its 

 antero-lateral margins, the more anterior being simpler in structure 

 than the posterior.^ The lateral eyes are simple ocelli in which the 



1 p. 141. 



Scorpion 



