TYPE ARACHNID A. 447 



orifice situated on the ventral surface of the first abdominal 

 segment. Plirynus is viviparous. 



5. Order Phalaugida. 



The Phalaugida (Fig. 205), popularly known as the Harvest 

 spiders, possess an unsegineuted cephalothorax (ct) and have 

 from six to nine segments composing the abdomen (ab). The 

 chelicerse are chelate, while the pedipalps (pe) are long and 

 leglike, with terminal ungues. The eight walking-legs are 

 usually exceedingly long, though in the genera Cyphoplithalmus 

 and Grwbocellum they are shorter. A single pair of stigmata 

 are usually all that occur ; they are situated upon the first 



FIG. 205. Leiobunum. 

 ab = abdomen. ct = cephalothorax. pe = pedipalps. 



abdominal segment and open into branching tracheae. In 

 Gibbocellum, however, two pairs occur, situated upon the 

 second and third abdominal segments, the anterior pair open- 

 ing into branched tracheae, while a bunch of simple unbranched 

 tracheae arises from each of the posterior ones. The heart 

 is somewhat elongated and possesses three pairs of ostia ; ar- 

 teries are entirely wanting, the blood passing from the heart 

 directly into the lacunar spaces. 



The digestive tract dilates into a sac-like stomach from 

 which numerous much-branched csecal diverticula pass off. 

 Malpighian vessels, two in number, are found in Cyphophfhal- 

 mus and Gibbocellum, and have been described as occurring 



