Podogona, Opiliones. 



07 



The existing species of Podogona are referable to the family Table-case 

 Cryptostemmatidac. They are small Arachnids, barely reaching ■'^°- ^^• 

 half an inch in length, and are confined to the forest-clad tracts of 

 tropical West Africa and Brazil. 



The group was represented in the Carboniferous period by the 

 y-enus Poliochera. 



Order 8.— Opiliones (Harvest-men). 



In the Opiliones the " cephalothorax " is confiueut with 

 abdomen throughout its width, and its carapace is either unseg- 

 mented or divided into two segments. Paired stink-glands open 

 on its dorsal surface near the 

 lateral margins. The palp is 

 not chelate. The abdomen is 

 clearly segmented, the somites 

 sometimes numbering as many 

 as ten. Eespiration is carried 

 on, as in the Pseudoscorpions, 

 by means of tracheal tubes 

 which open l)y a pair of 

 stigmata on the sternal plate 

 of the abdomen. 



Most of the Opiliones are 

 of rather small size, but some 

 of the South x\merican species 

 reach considerable dimensions. 

 They are exclusively carni- 

 vorous, feeding upon insects, 

 worms, and the like. The 

 female lays her eggs in crevices 

 of the soil, or any damp place, 

 and leaves them to their fate. 



The extinct Arachnida known as the Aiithracomayti, which 

 occur in the Carboniferous strata, are perhaps allied to the Opiliones. 

 A cast and drawings of one of these fossil forms are exhibited in the 

 Table-case (No. 25) with the Opiliones, and several casts and 

 specimens are shown in the Geological Department (Gallery 8, 

 Table-case 23). 



Sub-order I.— LANIATOEES. 



In these Opiliones the palp is often stout and furnished with a 

 strong prehensile claw. There is a single claw on each of the 



the Table-case 

 No. 25 



Fig. 70. 

 Gonijleptcs cliilensis. 



