MEMOIKS OF THE NATIONAL ACADEMY OF SCIE^JCES. 91 



•estradiscal line not always distinct, forming an oblique wedge shaped costal mark, wliieh is bent 

 outward on the subcostal vein and irregularly scalloi)e<l between all the venules, the space 

 inclosed by these two lines forming a broad obscurely luteous or clay-yellow band which is about 

 two or tlnee times as wide on the costal as on the inner edge of the wings. This broad band is, 

 especially in the 9. clouded with blackish scales toward the middle and hind edge, or in some 

 i S grayish near the costal edge. A submarginal twice-bent line ol)tusely bent in the second 

 median interspace, and again toward the apex of the wings. Fringe concolorous with the wings 

 and spotted with dark on the ends of the venules. 



Hind wings slightly paler than the fore wings, usually nearly as dark as the fore wings, 

 becoming darker toward and at the outer edge, sometimes with a dark cloud on the inner angle. 

 The wings beneath uniformly light ashen, with a distinct black costal spot on the outer third of 

 the fore wings, and on the hind wings just beyond the middle of the costal edge a dark blotch, 

 from which in some specimens a broad diffuse line passes in toward the middle of the wing. 



Length of body, c? , 1» to 12 mm.; 9 , 11 mm.; expanse of wings, S , L'7-30 mm.; 9 , 33 mm. 



The species will be recognized by the uniform cinereous tinge, by the three transverse lines 

 on the fore wings, by the broad clay-yellowish band, limited within by the slight inwardly curved 

 inner or second line and externally by the scalloped extradiscal line, and by the plain outer half 

 (if the wing, interrupted near the margin by the rather obscure twice waved darker line, and by 

 the plain hind wings. 



My original type, formerly in the museum of the Peabodv Academy of Science, Salem, is now 

 in my own collection. 



Having obtained a colored drawing of Walker's type in the British Museum (PI. VII. fig. 1), 

 there seems no reasonable doubt but that his name has priority. 



Efi!/. — Hemispherical m shape, though unusually low, shell smooth, shining greenish Avhen 

 fresh or the embryo is within, as the shell is unusually thin and transparent. Under a Tolles 

 trii)let the shell is seen to be very minutely pitted; under a half inch objective the shell is seen to 

 be ornamented with closely crowded, convex swellings or blebs, with a distinct swollen or thickened 

 hexagonal edge and a moderately sized central boss or low pajiilla. The egg is unusually small 

 compared with those of other Notodontians, especially those of Phronid dimldiatit, being only half 

 as large. Diameter, It mm. They are laid singly on the underside of the leaf of the aspen, and 

 from their greenish color and small size are difficult to detect. The larva emerges from the egg 

 through a bean shaped hole on one side of the egg, as in Pheosia. 



Liirra, Stage I. — Length when first hatched, before feeding, 2. .5 to 3 mm.: length when 

 described, soon after hatching, 4 mm. Head round, smooth, large, or twice wider than the body; 

 pale whitish green, nearly of the color of the body, which is whitish green, with no stripes, spots, 

 or markings of any kind; the body long and slender, rather flattened, with the sutures deeply 

 impressed, the segments being unusually convex, but entirely smooth, not wrinkled. The 

 glandular hairs (PI. YIII, fig. .'>) are very short, minute, moderately thick, and slightly swollen at 

 the end, which is divided into three rather slender i)rocesses or forks. Body tapering to the end, 

 which is not uplifted; in fact, the attitude of the young larva is singular, the body being curved 

 laterally so that the head nearly touches the tail. The larva feeds on the underside of the leaf 



The eggs and young larva were found July 2, on Birch Island, Casco Bay, Maine; some 

 freshly hatched larvae also occurred July (J. 



They had already spun on the underside of the leaf a roundish, white mat of silk, on which 

 the caterpillar rested preparatoiy to exuviation. 



When 7 mm. in length Just before molting (July 4) the head is still much wider than the 

 body, and now there are two liiiut dark dots on the head (on the vertex) and two subdorsal straw- 

 yellow lines extending from the front edge of the prothoracic segment to the suranal plate. The 

 sutures are also yellow. The body tapers from the prothoracic segment to the end. 



One molted July 5, and is described as follows: 



Larva, Staf/e II. — I/cngth at first, 7 mm: differs from Stage I in the two conspicuous black 

 dividing short bands on the head, ending above the eyes. The two yellow subdorsal lines and 

 the transverse linear bars formed by the yellow sutures are as at the end of Stage I. The body 

 is still rather flattened. The glandular hairs are retained in this stage, and are very short and of 

 the same shape as in Stage I. 



