$ 295. THE ARACHNOIDAE. 865 
ORDER II. 
Cephalothorax unarticulated, or biarticulated. Respiratory organs con- 
sisting of tracheae. 
SUB-ORDER II. ACARINA. 
Abdomen unarticulated and fused with the cephalothorax. Palpi simple. 
Famity: Acarea. 
Genera: Demodex, Sarcoptes, Glycyphagus, Tyroglyphus, Melichares, 
Dermaleichus, Acarus, Pteroptus. 
Famity: Hypracunea. 
Genera: Limnochares, Arrenurus, Eylais, Diplodontus, Hydrachna, Ataz. 
Famity: OnrpatEa, 
Genera: Hoplophora, Oribates, Zetes, Pelops, Damaeus. 
Famity: GAMAsEA, 
Genera: Dermanyssus, Uropoda, Gamasus, Argas. 
Famity: Txopza. 
Genus: Ixodes. 
Famity: Bortina. 
Genera: Bdeila, Molgus. 
Famity: Trompipina. 
Genera:. Erythraeus, Trombidium, Smaridia, Tetranychus, Rhyncholo- 
phus, Rhaphygnathus, Penthaleus. 
SUB-ORDER IV. OPILIONINA,. 
Abdomen articulated, but indistinctly separated from the cephalothorax, 
Palpi simple. 
Genera: Phalangium, Gonyleptes, Eusarcus. 
SUB-ORDER V. PSEUDOSCORPH. 
Abdomen articulated, but indistinctly separated from the cephalothorax. 
Palpi forficulate. 
Genera: Odisium, Chelifer. 
SUB-ORDER VI. SOLPUGIDAE. 
Abdomen articulated, distinctly separated from the cephalothorax. 
Palpi simple. 
Genus: Galeodes. 
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