Copy of plate 24 from from Testacea microscopica aliaque minuta ex generibus Argonauta et Nautilu...by Leopold von Fichtel and J.P.C.von Moll (New edition, Vienna, 1803. Inscribed below with captioning details. “Nautilus melo var...[chi and beta] Alveolina Melo...”
The two foraminifera [single-celled marine organisms with shells] in the illustration are reproduced under magnification, in section, and at actual size. In modern taxonomy, varieties of Borelis melo.