Proboscides of S-T bees. a, b, Colletes fulgidus Swenk; c, d, Halictus farinosus Smith. (a and c are outer views of maxillae; b and d are posterior views of labia.) The not or weakly sclerotized basal connections of the prementum are not shown in d. From Michener, 1944. (source: Michener, 2007)