The following new taxa are described: Drymaeus ( Drymaeus) cleefi, Drymaeus (Drymaeus) palassus and Drymaeus (Drymaeus) yapacanensis. The variation in the size of the sculpture of the protoconch is analyzed and two groups, which roughly correspond to the subgenera Drymaeus and Mesembrinus, are distinguished. Furthermore the variation in the mandibula and radula of 46 species is analyzed. Anatomical data are presented for 52 species and four species are redescribed.