20 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. in, 



black or black-brown silk threads, ■with round or broad oval interstices, as the fabric is extremely strong, tough, and 

 elastic, covered externally with moss and birch leaves firmly adherent" (III, 65). 



It is interesting that in the transformations of Rhesq/ntis erythrinse, aa figured by Burmeister, we have a parallel 

 to the case of Aglia tau. The fully grown larva is smooth-bodied and without the four long large thoracic spines, and the 

 caudal horns on the eighth and ninth abdominal segments of the previous stage. The genus appears to belong to the 

 Ceratocampidae. 



Although we are not yet acquainted with the early larval stages of Endromis, we do not see why the Sphingidae 

 may not have sprung from a form like this as much as from Aglia, as the shape and markings of the full-grown caterpillar 

 are much nearer a typical Sphinx than those of Aglia. Moreover, taxonomically, Aglia is by no means so "closely" 

 allied to the Sphingidse as Mr. Poulton in his able papers would lead us to infer. In its venation Endromis is much 

 nearer, and the latter is a more generalized or synthetic form than Aglia. From the Ceratocampidae the families of 

 Saturniidae and also of Hemileucidae may have originated, and indeed all the Bombyces, unless we accept the Arctians 

 and Lithosidae, may have evolved before the Sphingidae appeared. Judging by the characters of the head, the antennae, 

 throax, and especially the venation, the Sphingidae are far removed from the Ceratocampidae, and their origin from 

 the latter family was at least remote, and there must be some lost, extinct annectant forms which originally connected 

 them. 



POLYTHYSANA Walker. 



Polythysana Walker, Cat. Lep. Het. Br. Mus., VI, p. 1314, 1855. 

 Polythysana Kirby, Syn. Cat. Lep. Het., I, p. 785, 1892. 



Imago. — s and 9 head very small, eyes of moderate size, rather small. Front of the 

 head moderately wide, and with a shaggy vestiture. o* antennae widely pectinated, almost 

 plumose; the joints rather long and slender, those near the base longer than thick, those toward 

 the tips nearly three times as long as thick; the basal pectinations very long and slender, 

 densely ciliated; the distal ones a little shorter than the basal ones, but similarly ciliated. 9 

 antennas with short basal pectinations which are rather thick, about twice as long as the joints 

 in the middle of the antenna; the outer distal pectinations about one-third as long as the basal 

 ones, those on the inside vestigial, like minute teeth. Palpi small, short, drooping, not reach- 

 ing the front; they are rough and shaggy; third joint small, not visible. Thorax with vesti- 

 ture rough and shaggy, and with the abdomen bearing long, scattered, coarse, but not flattened 

 scales. 



Fore wings eminently falcate, especially in 6* , in $ slightly so ; costa moderately arched ; 

 apex squarish, truncated; behind the square apex the outer edge is considerably excavated. 

 Hind wings with the apex well rounded, outer edge moderately full and convex, especially 

 in 9 . The abdomen does not reach to the end of the hind wings in 3 , but it does in the 9 . 



Venation: Vein III! arising not far beyond middle of the discal cell; vein III 2 wanting; 

 vein IV 2 independent, its origin moved toward middle of discal cell; origin of IV situated mid- 

 way between those of III! and III 4 . In hind wings discal cell very long, the discal vein sit- 

 uated unusually near the outer edge, on outer third of the wing. Veins III, IV, and IV 2 aris- 

 ing at equal distances apart; IV 2 and IV 3 being very short, only one-third as long as the wing 

 itself. 



Markings : Rather striking, the ground color bright yellow and rose in 3 , with olive-green 

 hues in 9 • The distal spots forming large compound ocelli in the wings of both pairs; they 

 are centered with a linear white crescent. The basal line on the fore wings is broad and dis- 

 tinct. A distinct submarginal deeply sinuous dark line, and an apical roseate spot. 



Genitalia: Suranal plate triangular, broad at base (forked at the end; two partially dif- 

 ferentiated pairs of claspers, those of lower pair sickle shaped; the large convex and ending 

 in a long sharply incurved acute point; those of the upper small, bearing on the inner edge 

 two thumb-like processes. The suranal plate is triangular at the end, and the incurved tip is 

 divided into two blunt black forks. The penis is acute, style-like, slender, and there is a small 

 rounded triangular plate above it. 



This is a very distinct and easily recognized genus, though one difficult to locate, and it 

 is provisionally left in tins group; the broad plumose S antennas (in 9 with short branches) 

 and the square apex of the falcate fore wings, together with the very large and perfect ocellus 

 in each wing, are characteristic marks. 



