While working on the Treatise on Invertebrate Paleontology, Tappan Loeblich's research partner and husband Alfred was stationed in Europe by the Smithsonian Institution, in order to do further research on Foraminiferal samples seen in European museums, and those he collected in the field. Due to the USGS and their policy of not allowing work outside of the US, Tappan Loeblich took a leave of absence in order to join her husband in Europe. During their travels, the pair collected many samples, and greatly extended their knowledge on Foraminifera.
