458 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
a day 01 1 wo the caterpillar died and turned whitish, the rows of black warts becoming 
oonspionoaa. 
Full-grown larva. — Head coral-red, smooth abo%-e, deeply notched, but not tubercu- 
Iftfced, M ifl also tin- fourth (first abdouiiual) segment, which is humped, but the head 
is smooth and shining, the hump dull red. The dorsal aud aual regions dull yellow, 
with black waved Lines; tour white subdorsal Hues alternating with waved black 
Lines. Lower Liter*] yellow, with waved black lines. All the segments bear six or 
eight setiferons black tubercles, looking like black sealing-wax. Aual segment jet- 
black. Hairs all sordid white. Underside dull yellow, streaked with black waved 
lines. Abdominal legs yellowish flesh color; thoracic feet black. Length 30 mm 
<1.25 mi »). August 29-30. 
29. Cerura boreal is Boisd. 
Tlif caterpillar here described occurred iu August aud September at 
Brunswick, Me., ou the aspen. It apparently differs from those of 
€. occidentalis and cinerea iu the longer spines on the prothoracic seg- 
ment in the young larva, aud in the smooth slight rounded projections 
which replace them iu the full-grown caterpillar. 
Larva before last molt.— Length to base of caudal appendages ll mm . Head large, 
full, rounded, dark lilac-brown speckled with yellow, slightly wider than the body 
except the front part of the prothoracic segment ; the latter very broad, over twice 
as broad as long, the front edge laterally produced, and at each angle bearing a large 
long spiny tubercle three-fourths as long as the segment itself; the tubercle bearing 
about twelve setiferous spines; across the posterior edge of the segment is a row of 
four setiferous spines. On the back of the other segments are four short tubercles ar- 
ranged in a short trapezium, and on each side of the segments are two smaller sharp 
tubercles. The dorsal tubercles on the mesothoracic segment are larger than those 
behind; those on the metathoracic segment smaller than those on any other segment. 
The body tapers gradually to the end ; the supra-anal plate longer than broad, 
rounded, bearing two long large setiferous fleshy tubercles, which lie between the 
bases of the spiny anal legs or filaments, which are about one-half or two third> as 
long as the body, and yellow, with two broad brown rings, and brown at the tip. 
Body greenish yellow, marked as usual with lilac brown, this tint mimicking the 
dead withered brown of the edge of poplar leaves of late summer; it is a dark lilac 
brown with reddish brown and lilac brown patches, and in this way the caterpillar 
mimics the dead stained portion of the leaf on which it feeds aud thus escapes ob- 
servation. From head to end of mesothoracic segment a brown patch, succeeded by 
a pointed brown baud which exteuds to the base of caudal appendages but contracted 
ou the eighth abdomiual segment, the dorsal tubercles of which are yellow. 
Larva after last molt. — Length, except caudal appendages, 17 mm . Differs from 
foregoing stage in the prothoracic spiny horns beiug replaced by smooth, shining 
tubercles with faint traces of the spines of the former stage; the sides of the thoracic 
segments more distinctly spotted ; with faint traces of broken yellow lines in the 
middle of the body. 
The caudal appendages are soft and extensible on their outer third, 
forming the "flagelluni f* and are quickly jerked up when the creature 
is disturbed ; they are evidently delicate repellant organs. 
The close resemblance in the lilac-brown patches of this caterpillar 
and others of the genus to the sere and brown edges of certain of the 
leaves is remarkable, aud plainly enough serves to protect the cater. 
pillar from observation. I have observed the same in other Xotodon- 
tians, especially Schizura unicornis and allied forms. 
