2 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xii, 



Larva in its last stage spineless, smooth; in the early stages with 2 to 6 thoracic spines, 

 and a median double spine on eighth abdominal segment. Pupa like that of Eacles [Packard, 

 Psyche, Feb. 1902, p. 305]. 



Judging by the adult characters the Agliinse may be divided into three groups, the first 

 being represented by Arsenura, which appears to be the most generalized form, its ally, Dysdse- 

 monia, being more specialized, having undergone reduction in its maxillae, but a higher degree 

 of specialization as seen in its tailed hind wings, and the diaphanous discal and secondary 

 spots, as also the highly modified, almost simple, but densely ciliated antennas. The second 

 group is represented by Aglia, and apparently Baihyphlebia. 



The third by Polythysana. 



It is quite apparent that Aglia is an offshoot of the Arsenura phylum. As to the origin of 



Polythysana, that remains to be settled after we have a knowledge of the larva and all its stages. 



Until its transformations became known and comparisons made with those of Sphingidae and 



Ceratocampidae, the European Aglia tau was allowed to remain in the family Saturniidse, as 



formerly understood. 



ARSENURA Duncan. 



Phalxna-Attacus Cramer, Papillons Exotiques, III, t. 197A, 1782. 

 Arsenura Duncan, Naturalists Library, p. 125 (no description), "1837." 

 Rhescyntis group 2, Walker, Cat. Lep. Het. Br. Mus., VI, p. 1323, 1855. 

 Arsenura Drtjce, Biologia Centrali-amer., Lep. Het., I, 1886. 

 Arsenura Kirby, Syn. Cat. Lep. Het., 1, p. 769, 1892. 



Imago. — <? and ? . Head of moderate size; in front between the eyes unusually narrow, 

 the sides nearly parallel; when denuded, the front is unusually narrow, flat, not much narrower 

 at the front edge than at the vertex, even a little narrower than the width of one eye; eyes 

 rather large, round. 



Female antennae well pectinated to near the tip, the joints long, each one with two pairs 

 of densely ciliated pectinations; each pair of branches situated close together and of nearly 

 equal size and length, but diverging at their tips. Palpi porrect, very large, thick, longer than 

 usual, extending well beyond the front; third joint short and small, not very distinct from the 

 end of the second; when denuded the second joint is seen to be very long, about four times as 

 long as the basal one, the tliird joint being very small, almost minute. Maxillae vestigial, 

 either microscopic in size, forming two separate processes, one on each side of the mouth and 

 turned upward, or in A. xanthopus united, well developed, forming two coils. 



Fore wings of o* moderately wide, costa well curved toward the apex, which is rather 

 blunt, falcate, outer edge a little hollowed out; outer edge longer than the inner; wings of 9 

 wider, less arched on the costa and less falcate. Hind wings with no costal enlargement as in 

 Citheroniinas; the apex well rounded; outer edge with a well marked angle, almost suggesting 

 a tail, in 9 rounded ; above the angle the wing is somewhat excavated, less so in 9 than in <? . 



Venation nearly as in Citheronia; vein II 2 being present, but differs in vein III! arising at 

 the same point as the anterior discal vein ; vein III 2 arises nearly as far from vein IV, as from 

 III, ; vein II, arises far within the discal veins, toward the base of the wing. Discal cell small, 

 but larger than in Citheronia. 



In the hind wings vein II arises very near the discal vein and origin of III, ; the origin of 

 III, is nearly midway between that of III, and III 3 ; the two discal veins taken together form a 

 very oblique line. 



Legs rather long; odoriferous sack in fore tibia unusually narrow, pointed, slightly over 

 one-half as long as the tibia, acute at tip, lying at the bottom of a depression, and at the base 

 partly concealed by hairs. Abdomen rather slender and reaching nearly to the end of the hind 

 wings. Markings: Ground color fawn-brown, with only a slight indistinct line in place of a 

 discal spot; extradiscal line on each wing composed of a few large uneven scallops. 



Genitalia. — Suranal plate large, about twice as long as broad, the end curved in, extending 

 out as far as the upper clasper; the latter rather large, broad, the, end a single acute incurved 

 point, hook-like and roughened; seen from directly above or beneath they are narrow; the 



