THE SPJTtE-R ANX> ITS ALLIES 95 



man. Liobunum dorsatum is a common grayisli species 

 with a darker dorsal band, which emits a clear fluid when 

 handled (Fig. 92). 



The Areneina, or spiders, already considered. 



The Acarina, 1 or mites and ticks, in which, as in spiders, 

 the abdomen is unsegmented, but is fused with the cephalo- 

 thorax. Mites have typically a round body. They exhibit 

 great diversity of form and habits. All are 

 terrestrial, excepting one group of aquatic 

 mites, and are often of a bright red color 

 (Atax). The free-living species prey on 

 smaller animals, as well as dead organic 

 substances. Others are parasitic in animals 

 or plants, living in fur or feathers, 2 and even jjn e " ~ 



a sea- 



penetrating into the skin, as the small red - spider, x 1.5. 

 44 jigger" or " chigger " of our Southern fc^'aSS 

 States does. 



Finally, there lives in the sea an aberrant family of 

 spiders which crawl on the sea-bottom or over hydroids, 

 and thus have forsaken a terrestrial life for a completely 

 aquatic one (Fig. 94). 



APPENDIX TO CHAPTER VI 



KEY TO THE SEVEN SUBORDERS OF THE ARANEINA 



i. With 4 slits into lung sac [Tetrapneumones]. Che- 

 lifer claw directed downward ; 8 closely grouped 

 eyes .... . .. . . Territelarne 



(Tunnel-weavers) 



-2. 2 slits into lung sac [Dipneum ones]. Chelifer claw 

 directed inward. 



, mite. 2 rig . 93. 



