Assertion: spider's pair | /r/HasProperty | two pairs
Facets:
Source sentences:
text: Like pseudoscorpions and harvestmen, the Solifugae lack book lungs, having instead a well-developed tracheal system that inhales and exhales air through a number of spiracles; one pair between the second and third pair of walking legs, two pairs on the abdomen on abdominal segments three and four, and an unpaired spiracle on the fifth abdominal segment.