The text comprises an annotated Polish translation of two consecutive chapters of Claudius Aelianus’ De natura animalium (XVI 17–18), devoted to the island of Sri Lanka (in ancient times called Taprobana, later Ceylon). Chapter XVI 17 describes the great marine turtles, i.e. the leatherback sea turtles (Dermochelys coriacea Vandelli), massively killed by the local people. Chapter XVI 18 features the great Ceylon elephants (Elephas maximus maximus L.), as well as marine monsters that live in the Indian Ocean. The concise description of the coastal dugong (Dugong dugon Müller), contained in this chapter, is the only surviving evidence of the knowledge of this animal preserved in Geco-Roman literature.