A safety line is spun by the jumping spider Phidippus 

 audax even during a leap to a finger tip. (Colorado. 

 Walker Van Riper) 



month following October 24, when the sun is between 

 the earth and that constellation. 



Scorpions feed principally upon insects and spi- 

 ders, grasping them in the chelicerae and tearing 

 them to pieces or crushing them for their juices. Only 

 if a victim offers real resistance, or if the scorpion is 

 threatened by some enemy, is the sting brought into 

 use. Then the abdomen is arched forward over the 

 body (Plate 106) and the poison-bearing tip thrust 

 in vigorously. 



Medium-sized scorpions, such as the 2- to 3-inch 

 Centniioides scidptitratus and C. gertschi of the 

 American Southwest, have enough poison to be dan- 

 gerous, and it may be virulent enough to cause occa- 



The male jumping spider {Phidippus audax) uses 

 similar postures in courtship display and when threat- 

 ening a rival. This one is stimulated by his own image 

 in the mirror. (Colorado. Walker Van Riper) 



sional human deaths. In Egypt and other tropical and 

 subtropical countries, scorpion-stung people are fre- 

 quent enough so that an antitoxin has become a med- 

 ical necessity. 



Truly large scorpions, such as the 10-inch kinds in 

 equatorial Africa and tropical America, are compar- 

 atively inoffensive. Only toward other scorpions are 

 they hostile, and this habit is so characteristic of 

 scorpions of all kinds that they lead solitary lives. 

 Even well-fed females usually resort to cannibalism, 

 devouring the mate who has just fathered the next 

 generation of young. 



Scorpions bring forth their young as diminutive in- 

 dividuals, active and ready to fend for themselves. 

 Yet the offspring often cling to the mother's back for 

 many days after birth, riding with her wherever she 

 goes. From careful inspection of a mother scorpion 

 with her brood, it is easy to see that many sizes of 

 young are present. Ordinarily they are born one or 

 two at a time over a period of many weeks, rather 

 than the whole litter within a day or so. In some scor- 

 pions, a placenta-like tissue is formed within the par- 

 ent, permitting readier transfer of food and wastes 

 between the mother and her unborn young. 



WHIPSCORPIONS 



Arachnids include a variety of creatures suggesting 

 scorpions but entirely harmless to any animal larger 

 than an insect. The tailed whipscorpion Mastigoproc- 

 tiis (Plate 105) is a formidable-appearing denizen 

 of dark corners in tropical and subtropical lands. Its 

 abdomen suggests the broader basal part of the cor- 

 responding region of a true scorpion, but ends in a 

 long, flexible extension, the tail, with no venom. 



Tailless whipscorpions are equally retiring mem- 

 bers of the order Pedipalpi. In all whipscorpions the 

 pedipalpi are powerful and are used in grasping and 

 crushing spiders and insects as food. The first pair of 

 legs usually suggest whips — long, slender append- 

 ages ending in a flexible lash, used in the dark as the 

 animal feels its way about. In a large whipscorpion, 

 these legs may stretch 6 inches from side to side. 



PSEUDOSCORPIONS 



Diminutive pseudoscorpions (order Pseudoscor- 

 pionida) are encountered prowling for still smaller 

 insects among the stones along a sea beach. The larg- 

 est of them reach a length of about '4 of an inch, but 

 most are less than half this size. One of them invades 

 libraries, where it is known as the book scorpion, 

 Chelifer cancroides. Its flattened body, somewhat 

 suggesting that of a bedbug, is admirably fitted to 

 gliding between the pages. The creature runs about 

 on its four pairs of legs while holding up and forward 

 a greatly enlarged pair of pedipalps ending in pincers. 

 These are used in seizing tiny insects, such as the 

 young of silverfish and book lice (psocids), found 



