J 13 
Genus IPIIIAS, Boisd. 
The two conspicuous insects which at present com- 
pose this genus, were wont to he referred either to 
Pieris or Colias. They have certainly a close rela- 
tion to both, as well as to Anthocharis, but the fol- 
lowing characters seem to warrant their separation ; 
antenna; 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. 
