Other descriptive names for ovals and re-entrant branches cutting themselves may be used when required; thus, in the last-mentioned case a simple form is that of a figure of eight; such a form may break up into two ovals or into a doubly indented oval or hour-glass.
The inner "eyes" of the butterfly's wing may be hearts, ovals, circles, or even the couple's initials for uniqueness and personalization.
Forbes communicated to the Royal Society of Edinburgh a short paper of his on a mechanical method of tracing Cartesian ovals.
Descartes in the Geometric defined and considered the remarkable curves called of ter him the ovals of Descartes, or simply Cartesians, which will be again referred to.
A form which presents itself is when two ovals, one inside the other, unite, so as to give rise to a crunode - in default of a better name this may be called, after the curve of that name, a limacon.