506 ARACIINTDA. 



The Phalangiida (fig. 407) resemble the true spiders in their 

 general appearance, but differ from them by possessing chelate 

 chelicerse which are bent downwards, by the form of the abdomen, 

 the tracheal respiration, and the absence of spinning glands. The 

 Pedipalpi are either filiform or pediform, and are armed with claws. 

 The abdomen consists, as a rule, of six or more rarely eight or nine 

 segments, and is joined to the cephalo-thorax by its whole breadth. 



The nervous system is divided into a brain and a thoracic 

 ganglionic mass, whence arise two visceral nerves which form 

 ganglia in their course on either side. There are two or four 

 simple eyes. The organs of respiration, which in all cases consist 

 of tracheae branching within the body, open by a single pair of 

 stigmata, usually beneath the coxa of the last pair of legs. The 

 heart consists of a long dorsal vessel divided into three chambers. 

 The stomach is provided with a number of ceeca, of which the last 

 extend as far as the anus. The male as well as the female genital 

 opening lies between the posterior pair of legs. In the male a long 

 tubular copulatory organ, and in the female a long ovipositor can be 

 protruded from the opening (fig. 408). The production of ova as 

 well of spermatozoa in the testis, as was observed by Krohn and 

 Treviranus in almost all males, is remarkable. 



The Phalangiidce usually conceal themselves during the day and go 

 out at night to capture prey. The South American species are very 

 numerous, and of very strange form. 



Fam. Phalangiidae. With characters of the order. Phalangium opilio L. 

 (fig. 407). Gonyleptus liorridus Kirb. To this group also belongs CypliopJi- 

 tlialmiis duricorius Jos., and the genus Gibocellum Steck. 



Order 5. PEDIPALPI * (SCORPION-SPIDERS). 



AracJinida of considerable size ; jaws provided with claws, and the 

 anterior pair of the legs elongated, resembling antennae. The abdomen 

 has eleven or twelve segments, and is clearly marked off" from the rest 

 of the body. 



The Scorpion-spiders (fig. 409) are allied both to the Spiders and 

 the Scorpions. The abdomen, which is always separated from the 

 cephalo-thorax by a constricted portion, is divided into a considerable 

 number of segments, but presents no distinction into a broad prse- 

 abdomen and a thin styliform post-abdomen as in the Scorpions. 



* H. Lucas, ' Essai sur une monographic du genre Thelyphonus,'' Magax. 

 de Zool., 1835. J. v. d. Hoeven, "Bijdragen tot de kennis van het geslacht 

 Phrynus," Tijdsclir. voor nat. Gescliied. IX., 18-12. 



