94 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xn, 



■^ubterminal pale shade faint, subordinated. 



Pale lines of fore wing relieved on a dark ground without bordering shades, 



somewhat approximate below vindex Dyar; PI. LXXXII, fig. 15. 



Pale lines with inner blackish bordering shades and strongly approximated 



below solvex Dyai; PI. LXXXII, fig. 16. 



Abdomen of <? without ochreous hairs dorsally. 



Abdomen with lateral and ventral ochreous hairs, .frigida Schaus; PI. LXXXII, fig. 17. 



Abdominal hairs entirely black bouvereti Dognin. 



[Hylesia musculo, from Brazil, is figured on Plates LXXXIV, fig. 2, and CXII, figs, e, f, g, h, i, j.] 



MICRATTACUS Walker. 



Micrattacus Walker, Cat. Lep. Brit. Mus., VI, p. 1335, 1855. 



Micrattacus Kirby, Syn. Cat. Lep. Het., I, p. 774. 



Hylesia Herrich-Schaeffer, Sammlung Aussereur. Schmett., p. 60, 1856. 



Micrattacus Rothschild, Nov. Zool., II, p. 50, 1895. 



[Type of genus, M. nanus Walker.] 



Imago. — s . Head wide between the eyes, which are rather large. Antennas of <? short 

 and broad; pectinations in the middle a little longer than wide(?) about 12 pairs; tip sub- 

 filiform; distal ones arise close to the basal ones, and are shorter and difficult to detect; the 

 basal ones are densely ciliated. In 9 antennas simple, short. Palpi unusually short and 

 stout, not reaching the front; third joint not distinct. 



Fore wings unusually falcate, though not so much produced as in the s of Ludia; costa 

 not quite so much arched, but the apex is narrow and more acute, the outer edge more deeply 

 hollowed in behind the apex, and farther behind the outer edge is full and rounded, and the 

 inner angle well rounded. Hind wings triangular, reaching to the end of the abdomen; apex 

 well rounded, but the inner angle not slightly produced, as in Ludia. In the female the shape 

 of the wings closely resembles that of Hylesia nigricans, the wings being scarcely falcate, and 

 of the same hue and with the same kind of markings. Legs moderately thick and hairy. 



Venation: In fore wings very different from Sagana, and quite near to Eudelia. Vein IIj 

 arises just within the outer side of the discal cell (farther out than in Eudelia) ; vein II 2 wanting; 

 vein III 2 is entirely detached, being situated in the middle of the discal cell, and becoming a 

 true independent vein, as in Eudelia, Ludia, and Henucha. Median veins (III 3 -rV 2 ) much as 

 in Ludia. Hind wings much as in Ludia, differing from Sagana in vein III 2 , being independent. 

 The discal cell is shorter in the wings of both pairs than in Sagana or in Ludia and Henucha. 

 The female as figured by Herrich-Schaeffer is very different from the male, and differs generi- 

 cally, the fore wings are searcely falcate, and the hind wings are not triangular, and the color 

 is brownish, the discal spots being indistinct. 



Markings: Ground color fawn brown, with a large opaque oval discal spot on both wings, 

 those of the fore wings grayish; those of the hind wings tawny, tending to atrophy beneath, 

 especially on the fore wings. 



The wide head in front, the very short broad antennas, the short and stout palpi and 

 unusually falcate fore wings and triangular hind wings and its small size, with the large discal 

 ocelli on each wing, characterize this interesting form, though the $ is much more generalized 

 in shape and color. 



Geographical distribution. — Neogaeic realm, coast of southern Brazil. 



This genus, as shown by the venation, is somewhat intermediate between Sagana and the 

 Chilean Eudelia, and the South African genera Ludia and Henucha. The imaginal characters 

 are such as to show quite conclusively that these genera form a group common to the Neogaeic 

 and Ethiopian central and South African realms. 



The two sexes are remarkably unlike, and the species presents a notable example of sexual 

 dimorphism. The male departs widely in its very falcate fore wings, its triangular hind wings, 

 in its reddish-brown hues, and rather large round discal spots, from the dull dark obscurely 

 colored female. The case is a much more extreme one than that of Hyperchiria io, or Saturnia 

 pavonia-minor. It should be noticed that in venation the two sexes do not differ much; it is 

 in the less fundamental features of shape of the wings, the colors, and the markings that the 

 male differs generically from the other sex. 



[Dr. H. G. Dyar (in litt., 1912) considers Micrattacus a synonym of Hylesia.] 



