474 SYNOPTIC COLLECTION. 



the scales, leaving them as little hollow bags filled with 

 air. After this a dull ochre yellow or drab color suffuses 

 the wing excepting where the white spots of the mature 

 wing are to be (see PL 1208, fig. i). This color is due 

 to the fact that after the protoplasm has left the scales 

 the "blood" or haemolymph enters them and changes to 

 an ochre yellow and finally to a drab. About twenty-four 

 hours later the mature colors gradually develop, appear- 

 ing first between the nervures or veins (figs. 2, 3) and 

 finally on the nervures and anterior margin (fig. 4). 

 These colors are due to chemical changes taking place in 

 the haemolymph itself. 



It is interesting to note that ochre yellow and drab 

 tints which appear first after the white are the shades 

 peculiar to the more generalized nocturnal moths, while 

 the brilliant colors which are the result of more complex 

 chemical processes are found in the specialized diurnal 

 butterflies. 



When the insect is resting, the wings are held in an 

 erect position over the back. 



The power for sustained flight possessed by Danais is 

 exceptional. It migrates southward, flying long distances 

 in flocks numbering hundreds of thousands. It has also 

 been seen at sea five hundred miles from land (Scudder). 



Besides the legs and wings there are a pair of shoulder 

 lappets or patagia attached to the mesothorax which pro- 

 tect the hinge of the anterior wing from injuries. These 

 we have already seen in the hawk moths. 



The male is distinguished from the female by the black 

 patch next one of the veins near the middle of the hind 

 wings. This patch is really a little pocket containing 

 specialized scent scales or androconia. 



The family Nymphalidae includes many genera. Liby- 

 thea carinenta Cram. (No. 1209) is remarkable for having 

 long palpi which extend forward in the form of a beak. 

 Heliconius charitonius Linn. (No. 1210) is conspicuously 

 colored, while the mourning cloak, Vanessa antiopa (No. 



