272 MEMOIRS OF THE XATIOXAL ACADEMY OF SCIENCES. 



conical tubercles, each widi a short spine, tubercles one and two on joints 6 and 7 larger than the others. Cervical 

 shield colored like the head; horns red-brown, their tul)ercles paler; body green, a broad red-browu dorsal band, 

 very narrow and nearly obsolete on joints 3 and t, widening into an elliptical p,atch on joints 5-11 and inclosing on 

 joints 7 (posteriorly), 8, 9, and 10 (anteriorly) a i)atch of the ground color, faintly bisected by a brown dorsal line. 

 On joints 12 and l.S the band is faint, only tinging these segments. Tails red-brown, twice annulated with green; 

 length, 4.5 mm. Five days after the molt, the following description was made: Body highest at joint 3 posteriorly; 

 a red-brown dorsal band begins widely on joint 2, covering the horns, narrows to a line on joint 4, rapidly widens 

 and reaches the spiracle on joint 8; then narrows to a line on joint 12 and, widening again, covers the anal plate. 

 It is edged with yellow and contains, on joints 6-9, an ocherous yellow patch which is broken by a narrow, brown 

 dorsal line and the brown tubercles. The sides of the body are clear green, dotted with yellow. The anterior 

 aunulation of the tails is yellowish, the posterior one yellow. Venter, especially posteriorly, whitish. Joint 2 

 edged with yellow at the sides anteriorly. 



Fourth sluijr. — Head partly retracted beneath joint 2, shaped as before and colored much the same, but yellow 

 on the sides posteriorly; mouth parts whitish ; a few piliferous tubercles; width, l.fl mm. Prothoraeic horns thick, 

 pointing forward, covered with piliferous tubercles. The tubercles on the body are short, but bear stiff black set:c. 

 They are coucolorous with the markings except tubercles one and two on joints 6. 7, 10, and 11, which are larger 

 than the rest and blackish. Tails covered with spines which arise from enlarged bases. Body marked as in the last 

 part of the previous stage except that the paler patch on joints 6-9 is more brownish, and the anal plate is 

 tinged -with yellowish. Tails 5 mm. long, the extensile threads black, but white at base and middle. 



Two days after the molt the markings had more the aiipearance of the last stage, the central patch (that part 

 of the band on joints 4-11) being slightly indented along its edges in each segmental incisure. 



Fifth stage. — Head partly retracted below joint 2, rounded, higher than wide; clypeus small, depressed ; red- 

 brown, the upper two-thirds, except the clypeus, covered with little, round, yellowish dots, but leaving an obscure 

 line of the ground color on each side of the median suture; yellow at tiie sides posteriorly ; mouth parts pale, jaws 

 brown, antenna' yellowish; width, 3 mm. Cervical shield large, horns short, rounded, smooth, without tubercles 

 but sp.arsely punctured. Piliferous dots absent, the sefce short and fine. Tails spinose, turned u]i at the end. Body 

 pale yellow, thickly sprinkled with little whitish and brownisli dots, not very distinct; spiracles jiale brown; a 

 subventral row of brown spots corresponding to legs on the posterior apodal segments, and a medio-ventral line 

 posteriorly. Dorsal band ferruginous brown, consisting of three connected patches; tlie first triangular, covering 

 the horns, marked like the head on joint 2 and narrowing to a line at the elevation at joint 3 posteriorly ; the second 

 widens rapidly, reaching below the spiracle on joint 8. and narrows to a line on joint 11 posteriorly, being incised 

 on its edges in the segmental sutures, shaded with blackish brown around its borders, and containing a darker dorsal 

 and oblique subdorsal line, beside brown dots representing the tubercles; the third, on joint 12 posteriorly and joint 

 13, elliptical, covering the anal plate, but largely replaced by whitish. All the patches are bordered by a continuous 

 yellow line. Tails brown, green below at base and twice annulated with yellowish green; length, 6 mm. 



As the stage advances a purplish tint snft'uses the dorsal patches, the second one becomes darker, obscuring its 

 markings, but three pale orange patches appear in it on each side, behind the former oblique subdorsal lines, distinct 

 or confluent and becoming pinkish yellow. There is a narrow, reddish edging inside the now obscure yellow border. 



Cocoon. — Made, as usual in the genus, of pieces of bark and wood spun together over the hollow in the wood 

 from which they were bitten out by the larva. The cocoon is not so thick as that of Cenira ninlti.trripta, and it can 

 be indented by the finger. It fits the pupa closely. 



rtipa. — Cylindrical, slightl ,- flattened ventrally, the ends rounded; no cremaster. Color shining l>lackish brown, 

 the cases darker, almost black, wrinkled, and less shining than the abdomen. Length, 14 mm. ; width, i.b mm. 



Food plant. — Willow (.Salix). Larva' i'rom Yo Semite, Cal. 



If the larva' here described are not difl'erent from those of Cenira hicuspis Borkh. (which I can not determine at 

 ])resent), then the name scolo2>en{lrina nmst be referred to the synonymy; for all the characters of the European 

 species are exhibited in a series of specimens before me which were collected in California, Oregon, and Colorado. 

 I am satisfied th.at C. alhicoma .Strecker is only a v.arietal form, the transverse baud of the fore wings tending to be 

 narrower. 



Food plant. — Populus (Thaxter). 



Habits. — The moth (var. modcata) occurred at Plattsburg, N^. Y., and at Franconia, appearing 

 very early iu the .season, one beins;- taken by Mr. Hud.son at light May lo, May 9 to June 20, while 

 ^' occidentalism^ has not been taken before ]May 11, and cinerea and horealis not before the 2Sth. At 

 Taos, N. Mex., the normal foi-m was captured by Lieutenant Carpenter July 14. It is to be noticed 

 that the normal aquilonaris is paler, wluter, with less heavy black marks than mode.'ita. and is 

 most common in the We.st in the arid region, as well as at Washington, on Puget Sound, while 

 modesta is, so far as known, conftned to New England, and the darker forms i5f it to the cool and 

 damp region of the White Mountains. 



Geographical distribution. — Its range is very extensive, passing from the northern limits of 

 the Hudsonian fauna, if Franconia, N. II., be regarded as an outlier of that assemblage, and 

 extending throughout the Campestrian subprovince westward to the Pacific Coast, through Cali- 

 fornia, Oregon, and Washington, and southward into New Mexico. 



