The shell of Fagesia is about 9.5 cm (3.47 in) in diameter, typically with blunt umbilical tubercles from which spring 2 or three ribs each, but which are lost in the late growth stage. The suture is ammonitic with long spikey lobes and saddles with rounded subelements.
Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.