MEMOIES OF THE S'ATIONAL ACADEMY OF SCIENCES. 
197 
clash in front, but in the present stage these dashes are strengthened, united, broader, and 
colored more distinctly.) 
A noteworthy step taken at this stage is the final consolidation of the two doi*sal tubercles of 
the first abdominal segment, which now becomes a forked vsingle tubercle. 
Fourth stage, after the third molt , — Observed August Ck Length, lo-lO mm. The characters 
of the full-fed larva are now almost wholly assumed. The head is liigh and narrow, the vertex 
bearing two tubercles. The forked tubercle on the first abdominal segment is now larger and 
higher than that on the eighth segment; all are reddish, tipped with black. The body is much 
thicker than before and marbled, except on the pale pea-green meso- and inetathoracic portions, 
with reddish lines and spots, which are mucdi more numerous than before. Tiie hairs are now 
entirely changed in shape, being simple and j)ointed like those on the head. 
Fifth stage, after the fourth molt, — Observed August 10-18. Length, 25-27 mm., and finally 
35 mm. This stage does not differ essentially from the fourth, except that the horns are a little 
higher. The markings and colors of the matuie larva seem to be acquired in this stage. 
The essential or specific characters may be best brought out by comparison with the 
fully grown larvm of iS'. unieornis, S.ijwmew is larger and the hairs are longer. The head is 
les.s angular above and not so strongly marbled with the irregular network of reddish lines, and 
has four dark lines in two pairs extemling from the vertex to the base of the mandibles. The 
arrangement of the four double red and yellow dorsal lines between the head and the horn on 
the first abdominal segment is the same in the two species, but the. space they occupy is wider in 
/S', unmoruis, while the corresponding dorsal lines of the first behind the horn and the second 
and third segments are firmer, less wavy than in S, unicornis. The horn of the tirst abdominal 
segment is higher and slenderer, not so thick at the base as in S. tinicornis, while those on the 
eighth abdominal segment are much higher and more prominent. The four pairs of dorsal 
oblique lines S. unicornis are less distinct in S. ijwniew and more wavy, while the V-shaped 
dorsal mark just behind them is less sharp and distinct, with more red interlineations in S. ipomea\ 
‘ The following descriidion of two larvm found at Brunswick, Me., on the red maple, August 
14, describes the peculiar mimicking coloration better than those hitherto published: 
Full-groicn larva, — Length, 28-33 mm. Wonderfully mimics a dull blood-red portion of a leaf 
which had been cut partly off and become somewliat twisted, so that the larva itself would easily 
be mistaken for such a part of a prominent terminal leaf. The deception was perfect, as I did 
not myself at tirst see it when within ten inches of my eyes, and on holding it before the eyes of 
an observing boy of thirteen, he could not at first recognize it as a cater])illar. Tiie same leaf had 
blotches of dull red, and the flesh-red abdominal feet of the caterpillar clasped the concolorous 
red leafstalk. One larva was much deeper blood-red iu color thau the other, the latter having a 
more faded tint. , 
The head is high and narrow, not so wide as the body, but wider than the first thoracic 
segment; it is pale livid puiqilisli, darker down the front, with two parallel black-brown lines on 
each side, bordered with paler, and inclosing a clear xmle i)urplish band. The clypens, labrum, 
antenme, and region near the eyes are pale. A minute xDiliferous wart on each side of the vertex. 
The first thoracic segment is mottled with reddish and pale flesh on the sides. A dorsal broad 
band, divided in the middle by a pale yellow line, becomes one-half as wide behind on the second 
thoracic segment and x^asses back to the horn on the first abdominal segment; the rest of the 
second and third thoracic segments are i)ea-green, a little paler than the ux)per side, and darker 
than the underside of a red-max)le leaf, but on the whole very closely assimilated in tint to the 
color of the leaf. 
Tlic abdominal segments are in general faded, dull blood-red, due to flue, dark, flesh-red lines 
and mottlings on a pale carneous ground. On the first abdominal segment is a higli, nutant, llesliy, 
soft, dorsal tubercle which is inclined a little backward, but on being touched bends over down- 
ward near the back; the basal half is mottled and lined like the sides of the segment from which 
it rises, but above becomes bright, clear, blood-red, the end being deeplj^ forked, each fork bearing 
a long black bristle. A median black line ])asses along the tubercle, becoming forked in front 
and behind at the base. Two large, high, twin, soft tubercles on the fifth segment are not <iuito 
so large as the two similar ones on the eighth segment, but are situated ou a much larger humx); 
