This paper comprises a monographic treatment of the family Glabratellidae Loeblich and Tappan. The ecology and paleoecology of the family is discussed, the evolutionary tendencies and phylogenetic relations of the genera are explained, and the stratigraphic distribution of the genera is shown in a table. A total of 14 genera are described, 7 of them new: Heronallenita Seiglie and Bermúdez, gen. nov.; Neoglabratella Seiglie and Bermúdez, gen. nov.; Planoglabratella Seiglie and Bermúdez gen. nov.; Glabratellina Seiglie and Bermúdez, gen. nov.; Corrugatella Sieglie and Bermúdez, gen. nov; Fastigiella Seiglie and Bermúdez, gen. nov, and Claudostriatella Seiglie and Bermúdez gen. nov., in addition to the already described genera Trichohyalus Loeblich and Tappan, 1953; Pileolina Bermúdez, 1952; Heronallenia Chapman and Parr, 1931; Glabratella Dorreen, 1948; Pijpersia Thalmann, 1954; Angulodiscorbis Uchio, 1950 and Pseudoruttenia Le Calvez, 1959. A total of 95 species are recognized in this paper, most of them described and illustrated. The following 27 new species and a new subspecies are described: Glabratella testigoensis, G. elongata, G. truncorotaloides, G. hexacamerata, G. pennata, G. orientalis, G. baldai, G. mirabilis, G. mirabilis panamensis, G. winkleri, G. venezuelensis, G. cubensis, G. carinata, G. auratista, G. salosi, Glabratellina arcuata, G. duclozi, G. sigali, Heronallenia calida H.? pijpersiiformis, Heronallenita striatospinata, H. dorsocostata, H.? nana, Corrugatella danosoi, C. pijpersioides, Claudostriatella mexicana, Pijpersia ayalai, P. villasensis. Glabratella riveroae Seiglie and Bermúdez, new name, is proposed for the species Discorbina inflata Heron-Allen and Earland, 1924, which was a homonym of Discorbina inflata Perner, 1892.
