CLASS VSI. ORDER II. 9% 
ORDER 2. TRACHENTA. 
Having no cavity resembling lungs, but res pir- 
ing bya kind of trachea-like radiation of branched 
tubes. | 
PuHatancium, (grey-beard,) legs eight; eyes 
four, two vertical and two lateral; front furnish- 
ed with cheliform antenne ; abdomen generally 
rounded. 
Acarvs, (mite,) legs eight; eyes two, situate 
on each side of the head ; feelers two, jointed. 
leg-form. 
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