HARVESTMEN. 



121 



These consist of a comb and rasp, on the outside of the chelicerae and the inner sur- 

 face of the maxillae, which by being rubbed together produce a loud noise. 



The spiders of North America have been studied by Hentz, Emerton, Keyserling, 

 and Thorell. It is estimated that there are about eight hundred species in the United 



States. 



ORDER III. - - ARTHROGASTRA. 



This order is characterized by an unsegmented cephalothorax (except in the Solif ugse) 

 and a usually elongate abdomen in which the segments are more distinct, and which 

 is joined directly to the cephalothorax without the intervention of a slender petiole as 

 in the spiders. The chelicerae and palpi are frequently chelate. Respiration is effected 

 by means of pulmonary sacs in the scorpions and whip-scorpions, and by tracheae in the 

 other forms. 



SUB-ORDER I. --- OPILIONEA. 



Here come those slow-walking, long-legged forms familiarly known as harvestmen 

 and daddy-long-legs. They have two ocelli, small chelate chelicerae, and moderate 

 palpi. The legs are very long, and 

 the last or tarsal joint is broken up 

 into a long series of articulations, 

 sometimes as many as fifty in num- 

 ber. Not only in this many-jointed 

 structure but in function as well, 

 these elongate limbs seem to re- 

 semble antennae, for they are ap- 

 parently used as organs of sense, 

 and especially of touch, by those 

 animals. The daddy-long-legs are 

 perfectly harmless to man. They 

 live on small insects, and strive to 

 avoid the full glare of the sun 

 though they are not nocturnal in 

 habits. 



Members of this sub-order are 

 foiind in all parts of the world, and 

 in tropical countries, especially in 

 South America, they assume the 

 most bizarre forms. Three fami- 

 lies are described. 

 The GONYLEPTI- 

 DJE have the body 

 broad and de- 

 pressed, and the palpi and hinder femora spined. The species are 

 largely South American, Gonyleptes curvipes occurring in Chile. 

 Phryxus longipes is found in Mammoth Cave, Ky. The family 

 PIIALANGID^E embraces our more common forms. Fifteen species 

 of Phalangium are known from North America ; in the northern 



FIG. 174. Phalangium dorsatum, daddy-long-legs. 

 b. Male. Natural size. 



a. Female. 



FIG. 175. Cosmetus 

 ornatus, male, nat- 

 ural size. 



