Rhyngota: insects in which the mouth parts are prolonged into a beak or rostrum which serves as a protection to the piercing lancets: Hemiptera in the broad sense.
Rhythmical: occurring at regular intervals in the production of opposite conditions.
Rigid: inflexible: holding a direct course.
Rima: a crack or longitudinal opening with sharp edges.
Rimose: full of cracks.
Ring: a circle or annulus, usually margining a discolored spot.
Ringent: gaping.
Riparian: along the river or along shore.
Ripicolous: dwelling on river banks: riparian.
Rorulentum: dusty: =pulverulent: q.v.