The members of the genus Arrhopalites (Collembola Sminthuridae) found in the U.S. and Canada are described and illustrated. These include six previously described forms and seven new species: A. altus, A. clarus, A. bimus, A. bellingeri, A. dubius, A. hirtus, and A. amarus. Two forms known only from incomplete specimens are described, but not named. Nine of the species are found in caves, but only four of these are at present unknown from surface localities. The characteristics of the genus are described and discussed, and the genus Pseudarrhopalites Stach is placed in synonymy with Arrhopalites. New methods are developed for formulizing the structure of the female subanal appendage, and identifying the cephalic spines and setae.