CLASS VII. ORDER II. 97 



ORDER 2. TR AC HENT A. 



Having no cavity resembling lungs, but respir- 

 ing by a kind of trachea-like radiation of branched 

 tubes. 



PHALANGIUM, (grey-beard,) legs eight ; eyes 

 four, two vertical and two lateral ; front furnish- 

 ed with cheliform antennae ; abdomen generally 

 rounded. 



ACARUS, (mite,) legs eight ; eyes two, situate 

 on each side of the head ; feelers two, jointed,, 

 leg-form. 



9 



