The bicorn is the name of a collection of Quartic Curves studied by Sylvester in 1864 and Cayley
in 1867 (MacTutor Archive). The bicorn is given by the parametric equations
References
Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 147-149, 1972.
MacTutor History of Mathematics Archive. ``Bicorn.''
http://www-groups.dcs.st-and.ac.uk/~history/Curves/Bicorn.html.