//. ACES ATA: SOLPUGIDA. 



449 



Lung sacs, which are true appendages without lung leaves, occur 

 on abdominal segments four to six, and are eversible. The ovary 



FIG. 463. Koenenia wheeler i.* (From Wheeler.) 



is unpaired, the testes paired. There is a circumcesophageal nerve 

 ring and a single abdominal ganglion. No Malpighian tubes 

 occur. Kcenenia.* 



Order IV. Solpugida (Solifugae). 



In these the cephalothorax is broken up into a head bearing the 

 chelicerae, pedipalpi, and the first pair of legs; and three posterior 

 free somites, each bearing a pair of legs, thus giving these forms a 

 certain resemblance to the Hexapoda (infra). The chelicerae are 

 strong and chelate, the pedipalpi are simple and are used in walk- 

 ing, while the first pair of legs are tactile. Respiration occurs by 

 four pairs of tracheae, the first of which opens between the first and 



