3206 



THE JOINTED ANIMALS- 



in false scorpions, breathing is effected by means of tracheal tubes, opening by a 

 pair of orifices situated on the sternal plate of the abdomen, immediately behind 

 the coxae of the first pair of legs. In addition to these stigmata, there is one on 

 each side of the cephalothorax lying below the edge of the carapace and above the 

 coxa; of the first pair of legs. These were originally regarded as the apertures 



of breathing organs, 

 but it is now known 

 that they lead into 

 glands, probably se- 

 creting an odorous 

 and repellent fl u i d. 

 In some species of 

 harvest spiders, the 

 males and females are 

 almost exactly alike; 

 but usually the two 

 sexes are recognizable 

 by sharply marked 

 characteristics. In 

 the males, for instance, 

 the body is smaller 

 and often more 

 brightly colored, while 

 the legs are both longer 

 and more strongly 

 spined, some of their 

 segments being often 

 modified in shape. 

 The greatest modifi- 

 cation, however, is 

 found in the mandi- 

 bles, which are often 

 much enlarged; in the 



male of Phalangium cpilio, for example, the second segment is produced upward 

 into a great horn-like process. Fossil forms occur in the Carboniferous, one of which 

 has been described as Eophrynus. 



SOUTH-AMERICAN HARVEST SPIDER, Gonyleptes spinipes. 

 (Natural size.) 



SUBORDER Laniatores 



In the harvest spiders of this group the first sternal plates of the abdomen do 

 not project forward to any great distance between the coxae of the cephalothoracic 

 limbs; the first being thus separated from the mouth by a long though narrow 

 sternal area lying longitudinally between the coxae of the right and left sides. The 

 claw of the palpi is usually long, strong, and folded backward against the tarsus, 

 while the other segments are generally furnished with strong spines. Only the 



