1220 THE BUTTERFLIES OF NEW ENGLAND. 



the cell ; in all our nntive species (ami in all of those not resembling the Pierinae) 

 connected at the base to the submedian nervure by a short cross vein ; internal nerv- 

 ure connected \vith the submedian nervure at the base and running toward the inner 

 border. Hind wings rounded, the outer border usually crenate,(in the species which do 

 not resemble the Pierinae — such as Parnassius — usually') in our New England species 

 always with the last median nervule prolonged into a broad and long tail ; the same 

 is occasionally true of some of the other nervules. Costal nervure terminating at the 

 apex of the wing, emitting upward near the base a short and stout, usually curving or 

 Y-shaped shoot; frequently united, just beyond this, to the subcostal nervure by a 

 strougly oblique cross vein directed toward the base ; subcostal nervure united to the 

 median by a stout branch, as short as and sometimes shorter than its neighbors, and 

 attached nearer the second divarication of the median than of the subcostal, directed 

 a little inward in passing from the subcostal to the median nervure; first median nerv- 

 ule arising some distance beyond the middle of the cell ; internal nervure wanting ; 

 inner margin narrowly plaited and not forming a gutter for the reception of the abdo- 

 men. 



Legs very long, the hinder pair usu.ally a little longer than the middle; tibiae bare 

 of scales or provided scantily with them ; fore tibiae with a leaf-like appendage near 

 the middle of the inner side ; tarsi furnished above with four, below with two rows of 

 spines; claws long, but little curved, simple; paronychia wanting. 



.\bdominal appendages of the male with the upper organ very inconspicuous, the 

 centrum apparently obsolete, the hooks double, consisting of a pair of disconnected, 

 corrugated or subspiral ribbons at the base of the intromittent organ. Clasps with 

 the edges always smooth and those of opposite sides attingent, their inner surfaces 

 furnished with a conspicuous, more or less curving, prickly ridge. 



Egg. Nearly spherical, the sides arched more strongly than the summit, the base 

 flattened for attachment; surface with no external ornamentation bej'ond a slight 

 rugosity, but the substance of the shell reticulate; there is only slight variety of form 

 among the genera.* 



Caterpillar at birth. Head with no posteriorly descending surface above, where 

 it is partially enwrapped at rest by a fold of the first t'loracic segment. Body more 

 or less angulated at the lateral line instead of being nearly cylindrical as at maturity; 

 the segments furnished with several rows of distinct, bristle-bearing tubercles, one to 

 a segment in each row, those at the extremities of the body often larger and longer 

 than those in the middle, and frequently compound to a high degree, bearing many 

 diverging bristles. 



Mature caterpillar. Head considerably smaller than the first thoracic segment, 

 partially covered or hooded by the folds of tegument of the first thoracic segment. 

 Body cylindrical, [usually largest and sometimes considerably so near the anterior 

 end, tapering slightly toward the head and considerably backward ; the first thoracic 

 segment furnished upon the dorsum with a Y-shaped osmaterium, a fleshy, highly 

 colored scent organ of nearly uniform thickness throughout, completely retrac- 

 tile when not in use. Body almost entirely naked, sometimes furnished with long, 

 fleshy filaments, but otherwise only with smooth, hairless, lenticular, scarcely raised 

 disks or with very minute papillae bearing very minute hairs irregularly distributed. 

 Body marked with patches or transverse streaks of color, or by a diverse coloring for 

 dift"erent longitudinal regions of the body. 



Chrysalis. Head with a pair of anterior, lateral, more or less pyramidal promi- 

 nences — the ocellar protuberances. Dorsal surface of the abdomen ridged, if at all, 

 along the laterodorsal line ; posterior edge of the wings forming on the two sides about 

 a right angle with each other. Under surface swollen in the middle of the wings ; 

 lateral ridge including the upper edge of the wings. The anterior half of the body 



•One tribe, Parnassidi, not found in oblate with a distinct reticulation over the 

 America east of the Rocky Mountains, has an whole surface, giving it a pitted appear- 

 egg of a different type, the form being more ance. 



