The two conspicuous insects which at present compose this genus, were
wont to be referred either to Pieris or Colias. They have certainly a
close relation to both, as well as to _Anthocharis_, but the following
characters seem to warrant their separation; antennæ long, gradually
increasing into a club which is truncated at the extremity; palpi
contiguous and compressed, thickly covered with scales cut of equal
length, the terminal joint minute and truncated; head clothed with
rather long projecting scaly hairs; thorax robust; abdomen much shorter
than the inferior wings; wings very large and strong, the discoidal
cell closed. The caterpillar is attenuated at both extremities and
shagreened on the surface, the chrysalis much arched and fusiform at
both ends.