PAMPHILIDI: TIIK SPECIES OF TIIYMELICUS. 1695 



ligament and tlie prcanal button* or procremaster, ensnares itself in the 

 knobs or hooks witli which the latter ends anteriorly on either side, and 

 becoming on cxposiiirc a tenacious and flexible but structureless membrane, 

 the retaining membrane of Riley, does its share of the work to be accom- 

 plished. 



It is only by much lengthening and contracting of the abdominal seg- 

 ments, daring which the ventral side is much curved in the effort to with- 

 draw the tail, and which make it always seem as if the skin were itself 

 included in the telescopic action, as it sometimes actualh' is, that the imme- 

 diate purpose of the chrysalis is aecomplislied. Directly, the segments are 

 elongated and the cremaster darted as it were at the pad of silk ; once a 

 foothold or a claw-grasp here, and the rest is easy ; the cremastal hooks 

 become more and more entangled ; by writhings and whirlings of the body, 

 a greater and greater niunber become more and more deeply embedded, 

 while at the same time the i-apid drying of tlie now useless ligaments 

 causes their rupture from the larval skin, which, shrivelled and loosened, 

 drops to the ground, leaving the chrysalis in firm possession of the button 

 of silk. 



BIBLIOGRAPHY. 



Osborne, .J. A. On the pupation of the Nymplialiilae. Ent. monthl. mag., xv: 59-61, 1878. 

 Edwards, W. H. On the pupation of the Nyinphalid.ae. Can. ent., x : -224-231, 1878. 

 Eiley, C. Y. Philosophy of the pupation of liutterflies. and particularly of the Nymphalidae. 

 Am. ent., iii : 162-167, 1880. 



Table of the species of Thymelicus, based on the egg. 



Eg^ nearly twice as broad as high aetna. 



Egg less than half as broad again as high mystic. 



Brettus not examined. 



Table of species, based on the caterpillar at birth. 



Ranged bristles of superior rows distinctly more than half as long as a segment aetna. 



Ranged bristles of superior rows distinctly less than half as long as a segment mystic. 



Brettus not examined. 



Table of species, based on the mature caterpillar. 



Front of head more or less streaked, vertically. 



Frontal triangle dark aetna. 



Frontal triangle yellowish white brettus. 



Front of head with no vertical stripes mystic. 



*By this term I have described in the text the special parts developed on or within them 



the often complex parts surrounding the blind or at their anterior extremity. Procremaster 



rectal tissure of the chrysalis, including the would be a simpler term, including all the parts 



ridges at the ventral base of the cremaster, in front of the cremaster or suspensory but- 



those which surround the rectal fissure, and ton. 



