: 908 POLYMORPHIC BUTTERFLY. 
Maryland (Uhler) it is “rare” and about Philadelphia (Blake) it 
is not common. Finally, one specimen has been taken near 
Brooklyn, N. Y. (Graef fide Akhurst). i 
As in some other dimorphic species, however, the distribution 
of the several varieties does not seem to be coextensive with that 
of the species. Unfortunately, our information here is very 
meagre, since the polymorphism of the insect has only recently 
been proved. It is; however, certain that the numerical superi- - 
ority of the variety Marcellus over Walshii and Telamonides is 
far greater in the north than in the south; indeed, near the 
northern limit of the insect’s range, Walshii and Telamonides are 
‘hardly known, and in extreme northern localities where only a few | 
specimens have been recorded, these have always been Marcellus. 
` The caterpillar, according to numerous authorities, feeds upon 
the papaw (Asimina triloba Dunal) and, according to Dr. Chapman, 
upon other species of the same genus such as A. parviflora Dunal, 
` A. grandiflora Dunal, and A. pygmea Dunal. Boisduval and Le — 
Conte also state that it feeds upon the latter and upon A. palus 
tris,—plants belonging to the Anonacez or custard-apple family. 
Some of the caterpillars, as shown by Mr. Edwards’ observations, 
attain their full growth in twelve days, although others, especially 
the produce of the form Walshii, requirenearly a month. They — 
do not draw the leaves of the plant together like the larve of the 
genera represented by Troilus and Glaucus. They are.to be found 
in every stage “‘ resting on the surfaces of the leaves, and one would 
suppose they must be nearly exterminated by birds. But like all an 
Papilio larve they emit from the head [first thoracic segment], at , 
the same time that they project a Y-shaped tentacle, a pecu i a 
acrid and. sickening odor, which must effectually protect them. a 
In a letter, Mr. Edwards adds that he does “ not believe a starving : 
bird would touch one, the stench being so strong as nearly 10 
‘turn one’s stomach.” : — 
_ Science is deeply indebted to Mr. Edwards, for the thorough 
manner in which he has worked out the history of this. butte) — 
PARIER 
sumed to be identical), but has proved the existence of a third a | 
* Edwards, Butterflies N. America, part ix. 
