This paisley is constructed from a semicircle for the head and two simple spiral segments for the boundaries of the tail. It is defined by
,
,
and
.
is the radius of the circle that the spine of the paisley is on.
is the radius of the semicircle defining the head.
is the coordinate of the tail of the paisley.
is the coordinate of the center of the semicircle head of the paisley.
Unfortunately the junction between the semicircle and the spiral segments are sharp.
While there is certainly a circle for a given radius which can be tangent to both of those spirals, At this stage I am too lazy to do the math necessary to calculate it.