226 AUGUSTA RUCKER. 



three species which I examined, the ventral view showing the 

 relative size of these set^e, the arrangement of the hairs of 

 the fourth, fifth, and sixth segments of the abdomen, and tlie 

 number and arrangement of the cephalothoracic sternal hairs, 

 give an immediate clue to the species. In arranging any 

 analytical table these specific points should come first in 

 consideration. The females, which probably differ from the 

 males only in their reproductive appendages, must be used 

 entirely in furnishing the description for the species. 



A. Lung-sacs present on the ventral side of the 

 fourth, fifth, and sixth segments of the abdomen. 



Prokoenenia. 



1. Between the lung-sacs on segments 4 and 5 are 

 three pairs of long backward turning hairs. These hairs are 

 absent on segment 6. A group of four shorter hairs is 

 present for protection over the aperture on each lung-sac. 

 Usually fifteen cephalothoracic sternal hairs are present, 

 eio-ht of which are arranged in a transverse row, and seven 

 form a V anterior to this row. The three setas of the proxi- 

 mal joint of the chelicerte of equal size. Labrum rounded 

 anteriorly, and possessing along its lip six pairs of delicate 

 hairs. A group of four lateral sense-organs present on a 

 side. The stiff, hollow seta is situated on the distal limit of 

 the third metatarsus of the first leg. 



Koenenia (Prokoenenia) wheeleri. Rucker. 



2. No long hairs are present between the lung-sacs. 

 Ventral surfaces of the fourth, fifth, and sixth segments 

 are alike. A group of three haii-s is present over the orifice 

 of each lung-sac. Eight cephalothoracic sternal hairs are 

 present, arranged at the corners of two concentric rectangles. 

 Two lateral sense-organs are present on a side. Tlie flat, 

 hollow seta is situated at the middle of the third metatarsus 

 of the first leg. 



Koenenia (Prokoenenia) chilensis. TTauseu. 



