196 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



entirely yellow, tinged with orange. In another the fore wings are 

 wholly black, with no trace of yellow. These, and others, are likely 

 to be found at any time in this vicinity. 



The great majority of the females fall into one or other of two 

 types. 



The commonest females (pi. 41, fig. 2) are grayish black. The 

 spots of the inner row on the fore wings are represented by the first 

 four, much reduced, with traces of the other three. On the hind 

 wings the uppermost spot is large, the second is much reduced, and 

 from one to three preceding the last, or sometimes all, are more or 

 less developed. Rarely all the yellow spots of the inner row, except 

 for the first and last on the hind wings, are absent. 



Frequently females are found which are deeper black and have 

 all the spots of the inner row present and well developed, and in addi- 

 tion a conspicuous yellow bar across the end of the cell of the fore 

 wings. 



Cater pillofr'. — The caterpillar, which is the common parsley worm 

 of gardens, is bright green, each segment with a broad black band 

 punctuated with conspicuous bright yellow spots across the middle 

 and narrowly edged anteriorly with black. 



It feeds on a very large variety of umbelliferous plants, including 

 even the most poisonous, such as the poison hemlock (Coniimi macu- 

 latvmh). In the District it feeds chiefly on the wild carrot and on 

 cultivated parsley, carrots, parsnips, and celery, to which it some- 

 times does considerable damage. It has only very rarely been found 

 feeding on plants of other groups. 



Chrysalis. — The chrysalis has a rugged and rugose surface, and the 

 anterior half is bent backward at a considerable angle, whereby it is 

 readily distinguished from the chrysalis of the yellow swallowtail. 

 It is distinguished from the much larger chrysalis of the giant swal- 

 lowtail {Papilio cresphontes) by its more slender build, less strongly 

 curved ventral profile, and the absence of a prominent compressed 

 tubercle at the base of the antennae. In color the chrysalis is dingy 

 mottled brown, sometimes with dark-green markings. E. J. Smith 

 once showed me two chrysalids that were wholly bright yellowish 

 green. 



Remarks. — This species scarcely differs except in color from the 

 Old-World Papilio niachaon. I am familiar with both in life, and 

 I can not see that the habits of the two differ in the slightest degree. 

 Furthermore, the odors of the males are the same. 



The variability in the size of the yellow markings, especially in 

 the males, seems to indicate a form that is in a state of unstable 

 equilibrium, a black species belonging to a group the normal color of 

 which is yellow and showing a constant tendency to revert toward 

 the fundamental yellow color type. In other words, I believe that the 



