CHAPTER IX 



HARVEST-SPIDERS 



Classification and distribution 



The order Opiliones or Phalangidea includes the harvestmen, 

 the majority of which can be recognised by their long, slender legs 

 and segmented abdomen which is joined to the cephalothorax 

 across the whole breadth and not by a narrow pedicel as in spiders. 

 The cephalothorax is composed of six segments and is often separ- 

 ated from the abdomen by a fairly deep groove. The carapace is 

 usually smooth and, in most species, bears two eyes, although these 

 may occasionally be absent. The eyes are nearly always situated on 

 a prominent ocular tubercle near the middle of the cephalothorax, 

 one looking out at each side. Near the anterior margin of the pro- 

 soma opposite the attachment of the first pair of legs there are two 

 small openings leading to a pair of odoriferous glands: the glands 

 themselves can, in some species, be seen through the carapace 

 when they look like an extra pair of eyes. The chelicerae are three- 

 segmented, the last two segments forming pincers, while the pedi- 

 palps are of six segments. Their coxae bear gnathobases which 

 form part of a complex mouth. The pedipalps are short and leg- 

 like; they are chiefly sensory organs for use in contact with objects 

 close to the body, and they also help in grasping the food and 

 bringing it to the jaws. In some genera they end in a claw which 

 may be smooth or toothed, but in others no claw is found. 



The bodies of harvest-spiders are usually covered with spines, 

 pointed tubercles and bristles. There is often a double row along 

 the centre of the ocular tubercle and in some genera of Palpatores 

 (see below) a group forms a trident in the middle of the fore-edge 

 of the cephalothorax and is an important diagnostic character. On 

 the underside of the body the coxae of the legs almost meet in the 

 middle so that there is no sternum as in spiders. 



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