Miksa Hantken (1821–1893), the father of Hungarian micropaleontology, prepared numerous collections of foraminifera during his career, which are now housed in major museums and scientific institutions across Europe. Thanks to the long-standing professional and friendly relationship between Hantken and Capellini (1833–1922), the Giovanni Capellini Geological Museum still preserves some of Hantken’s collections. These remain largely unknown but could be among the most extensive outside Hungary. This study examines the foraminiferal collection from the “Clavulina Szaboi beds” (Eocene–Oligocene). As far as possible, the history of the collection has been reconstructed, also through correspondence between Hantken and Capellini. The analysis revealed 60 foraminiferal species, 18 of which were established by Hantken, mainly from successions near Budapest that are no longer exposed. Specifically, specimens of six species established by Hantken, which had not been considered in previous studies on his collections, were identified. While a substantial consistency was observed between the specimens of these species and Hantken’s descriptions and illustrations, their state of preservation allowed the designation of a lectotype to clarify species characteristics only for Zsigmondiella zsigmondyi and Anomalinoides granosus. For the former, it was possible to observe the initial spiral coiling and a distinctive ornamentation not reported in the type description and figures but frequently mentioned by later authors. Regarding Anomalinoides granosus, a species with a wide geographical distribution and frequently observed in Cenozoic successions, its validity has been confirmed despite the synonymies proposed in the past by some authors. Additionally, the relationships with the variety Anomalinoides granosus var. dibollensis were highlighted, thanks to topotypes housed in the museum.