A striking example of the art of tessellating. These reptiles are the result of repeating the same 6 sided figure in sets of three over and over. Escher developed his own classification system for all his Regular Divisions of the Plane, it can be found in Doris Schattschneider's book, Visions of Symmetry. Escher classified this print as 'Triangle system I A3 type I'. This is the only book we know of dedicated to the study of Escher's watercolors and tessellations, this book also contains the complete text of a couple of his notebooks. This particular symmetry is the foundation for the lithograph Reptiles, which Escher completed in 1943.