FAMILY TYPICAL BUTTERFLIES. 133 



habits render not improbable; in what stage it hibernates 

 is unknown^ but probably as a butterfly, or else as a cater- 

 pillar. The eggs, which are yellow, subfusiform, about 

 twice as high as broad and with about seventeen vertical 

 ribs, are laid singly on the more tender leaves of the food- 

 plant. Cassia. The chrysalis hangs ten or twelve days. 

 The male butterfly has an odor like violets. 



Two other species of Callidryas occur rarely in the extreme south- 

 ern limits of our district, in the West: G. sennae and G. philea. 



35. Genus Zerene. 

 ZERENE CAESONIA— THE DOG'S HEAD. 



(Colias caesonia, Meganostoma caesonia, Zerene cesonia.) 



Butterfly. — Upper surface of wings lemon-yellow, the fore 

 wings having the outer border very broadly margined with black, 

 its inner limit so deeply indented, especially in the male, that, 

 with the black dusting of the basal part of the cell and a large 

 round black spot at the tip of the cell, a dog's head is vividly 

 outlined, the round spot forming the eye. Under surface almost 

 uniform yellow, more or less edged and dotted with roseate, the 

 black spot of the fore wings repeated, here with a silvery pupil, 

 and the hind wings with a pair of silver spots enclosed in a 

 roseate or ferruginous nebula. Expanse 2l-2| inches. 



Caterpillar. — Head yellow-green. Body naked but sparsely 

 pilose, yellow-green, usually with narrow transverse bands of 

 yellow or black or both, and studded on each segment with a 

 single transverse series of black or concolorous papillae. Length 

 nearly f inch. 



Chrysalis. — Body not bent in the middle, the wing-cases only 

 moderately protuberant, frontal horn short; bluish green with 

 whitish creases and above with two longitudinal rows of black 

 dots, the wings dark green. Length nearly f inch. 



This, a common species in the Southern States and 

 especially in the West, occurs in some abundance in the 

 southernmost parts of our district, and has been found as 

 far north as Pennsylvania, southern Ontario, Wisconsin, 



