(required) a data frame, possibly a result from the
colspace() or segspace() function, containing values for 'LM' and 'MS'
as columns (labeled as such).
labels
logical. Should the name of each cone be printed next to the
corresponding vertex?
tick.loc
a numeric vector specifying the location of tick marks on x &
y axes.
square
logical. Should the aspect ratio of the plot be held to 1:1?
(defaults to TRUE).
Endler, J. A. (1990) On the measurement and classification of
colour in studies of animal colour patterns. Biological Journal of the
Linnean Society, 41, 315-352.