394 



ARTHROPODA 



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

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

 'thoracic' somites, a condition which deserves embryological investigation. 

 The abdomen consists of nine or ten somites, and the head bears two ocelli. As 

 the name implies, the Solpugidae are nocturnal, living by day in holes in the sand 

 and searching for their prey at night. In the Old World they are reputed as 

 poisonous, but no poison glands occur. Solpuga,* Galeodes,* Datamcs* (fig. 424). 



FIG. 424. 



FIG. 424. Datames formidibilis* (after Putnam). 

 FIG. 425. Chelifer braraisi (from Schmarda). 



FIG. 425. 

 i, chelicerar, 2, pedipalpi. 



Order V. Pseudoscorpii. 



These small flattened forms resemble the true scorpions in the chelate 

 chelicerae and pedipalpi (fig. 425), and in the abdomen joined by its whole 

 breadth to the thorax. They differ in the lack of postabdomen and sting. 

 They breathe by tracheae; have from two to four ocelli, and spinning glands 

 opening on the second abdominal somite. These animals, 2-3 mm. long, live 

 in moss, etc., and among dusty books, feeding on mites and minute insects. 

 Chelifer * Obisiuin* Chernes.* 



Order VI. Phalangida. 



The abdomen in the harvestman, or 'daddy long legs,' is less evidently 

 segmented than in the forms already mentioned, nor is it sharply distinct from 

 the cephalothorax. The small body bears four pairs of exceedingly long legs; 

 the chelicerae are drawn out in long horny processes; the pedipalpi are tactile 

 organs as in the true spiders. The males possess a long penis, and the females 

 a long ovipositor. They have two or four ocelli and breathe by tracheae. These 

 largely nocturnal animals are predaceous, feeding upon small mites. In struc- 

 ture they form in some ways an approach to the Acarina. Phalangium* 

 Liobunum* 



