3-dimensional table

Hi,

Last week my class conducted an experiment by putting out clay
caterpillars to look at the effects of urbanization, color, and location
on caterpillar predation.  There were two sites (urban, rural), three
colors (green, yellow, red) and two locations at each site (edge,
interior).  The entire data set is below.  I've checked out the MASS
book, Dalgaard's book, and the R-help archives and I haven't found
anything that suggests how to set up a spreadsheet for the xtab function
(say, xtab(predation ~ location + site + color, data=class).   It would
not be a problem to input the data by hand but I wouldn't know how to
set that up either.  Any suggestions would be greatly appreciated.  The
class is mostly college sophmores and juniors and biology and education
majors.  We are using R 2.2.1 on Windows XP.