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Genus CALLIDRYAS. 
This genus is composed of a selection of species 
from Colias, to which it hears a very close relation. 
It is not long since it was proposed by Dr Bois- 
duval, who thinks that the following characters 
entitle it to this distinction. Palpi approximating 
and very much compressed, clothed with short hairs 
and dense scales, the terminal joint conical and much 
shorter than the preceding one ; antennas thickening 
gradually from the base to the apex, which is dis- 
tinctly truncated ; body robust, the abdomen much 
shorter than the inferior wings ; the latter forming 
a groove which completely embraces the under side 
of the abdomen. The caterpillars are naked and 
somewhat attenuated at both extremities ; the chry- 
salis arched, or boat shaped, with the extremities 
drawn out to a narrow point ; always attached by 
the tail and a transverse hand. 
According to the manner in which they have 
been respectively constituted, Callidryas therefore 
is best distinguished from Colias by the antennas, 
which in the latter terminate in an obconical club ; 
and from Tihodocera (including Gonopteryx of Dr. 
Leach), which has these organs likewise truncated, 
by the shape of the wings, which never present acute 
angular projections. The prevailing colour of the 
