The basic were-jaguar motif combines a cleft head, slanting almond-shaped eyes with round irises, and a downturned open mouth with a upper lip and toothless gums. This motif was first described in print by Marshall Saville in 1929 and expanded upon by artist and archaeologist Miguel Covarrubias in his 1946 and 1957 books. In this latter book, "Indian Art of Mexico & Central America", Covarrubias included a family tree showing the "jaguar mask" as ancestral to all (later) Mesoamerican rain gods.