PHYLUM ARTHROPODA — CLASS ARACHNIDA 299 



The Phalangida, commonly called harvestmen and daddy longlegs, 

 can be distinguished from other arachnids by their body which is 

 composed of a broadly fused cephalothorax and abdomen, the ab- 

 domen consisting of nine segments; long legs; and the presence of 

 only two eyes on the cephalothorax. The reproductive organs, an 

 ovipositor in the female and a penial organ in the male, are located 

 on the obscure division between the cephalothorax and abdomen. 

 The respiratory organs consist of tracheae which open through ab- 

 dominal spiracles. The harvestmen do not have silk glands and 

 therefore do not construct cocoons for the eggs, which they lay under 

 stones and under the bark of trees. There are about seventy species 

 in the United States, representing six families. Species of the family 

 Phalangididae are the most common and widely distributed. 



The order XipJwsura, king crab, is represented by only one living 

 primitive genus and five species. Limulus polyphemus is the Ameri- 

 can species found along the Atlantic Coast from Maine southward. 

 Because of its shape and resemblance to the crabs, it has been called 

 the horseshoe crab. The body consists of two regions; the cephalo- 

 thorax and the abdomen. There are six pairs of appendages on the 

 cephalothorax. The basal parts of the appendages situated around 

 the mouth are used for crushing the food, which consists mainly of 

 worms. On the abdomen are six pairs of appendages, the last five 

 pairs bearing book-gill structures used in respiration. The males are 

 a little smaller than the females, but similar in appearance. The 

 eggs are deposited in the summer in shallow water in small sandy 

 depressions w^here they are then fertilized by the male. 



