240 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Two young with horns exactly as in PI. XXXII, figs. 2, 2rt, were found on the maple August 

 20-29; one of them molted August 27, and then ai)peaied as in PI. XXXII, flgs. .'5, 3a. When tirst 

 found they were stretched out motionless along the nudrib ou the underside of the leaf. 



In the last stage the larva differs from that of H. fiiiitirittn in having the three pairs of 

 lateral sere brown patches, the difference l)eing simply colorational rather than as regards the 

 arnuiture. 



llie lost stujie. — Length, 30 mm. The head is still high, bilobed, narrowing toward the vertex, 

 with two black lines in front extending from each side of the elypeus and ending on the vertex 

 near the tubercles, and another behind one on each side extending from the antenna- and 

 mandibles back halfway up the back side of the head. 



The antlers of the early stage are now replaced by two high, conical, rounded, i)olished knobs, 

 each bearing a minute bristle, and from them on the inside two parallel lines extend backward. 



The aiuil legs are shorter than in the early stage, being about as long as the -well-rounded 

 supraanal plate. Donbleday probably gives the characteristic attitude of this caterpillar when 

 not walking, its legs being jnoderately elevated. 



I add a fuller description of this larva when fully grown. 



Mature ho-ca. — Length, 3.5 mm. Head high, narrowing from below to the vertex, which is 

 very slightly bilobed. Two black lines ascend from the antenna; and approach each other on the 

 vertex, the space between tiie lines slightly roseate; outside the head is liglit uniform brown with 

 a slight greenish and Idac tinge; the elypeus is small, while the median suture of the epicranium 

 in front is very distinct. On the prothoracic segment behind the vertex are two contiguous, thick, 

 conspicuous, large, conical, bright red tubercles, dark at the tip; there are no other humps, and 

 none at the end of the body, which is thickest at and a little behind the middle, the body tapering 

 gradually to the long anal legs, which fork widely and are longer than the others, but are constantly 

 used. Supraanal plate unusually small. Color of a peculiar brownish green dotted with black 

 points and specks, with a white spot between the prothoracic tubercles. Body above finely 

 marbled with dark brown, with a broken, pale, flesh-colored line, beginning on the mesothoracic 

 segment, and ou the first to third abdominal segments suddenly expanding into a large, broad, 

 sublozenge shaped spot, suddenly succeeded, over the segment bea.ring the first pair of abdominal 

 legs, by a rounded spot. On the top of the fifth segment begins another dorsal patch of the 

 same color, which widens and extends down the sides of the third segment from the end. Along 

 the middle of this patch are two parallel dark lines; and two broader dark lines of speckles begin 

 on the fourth segment from the end of the body, converging and uniting on the second segment 

 from the end, forming ou the last two segments a broad median dorsal line. Thoracic legs reddish; 

 abdominal legs reddish flesh color. Anal legs slender, reddish. On the oak at Providence, 

 October 9. 



To recapitulate: 



1. The pair of prothoracic antlers of the early stage of this larva, and those of (jnttiritta 

 ohliqua and umbrata, is certainly the most unique and unexpected feature to be found among 

 Lepidopterous larva', and the object evidently is to render the creature frightlul to its assailants. 



2. The rest of the body is without large horns aiul markings, the latter of which appear in. the 

 later stages and are such as to completely adapt it to a maple leaf late in summer or in the autumn 

 when portions begin to wither and to turn brown. Hence the horns, if present, would then only 

 serve to attract attention to it, and thus they are modified into nuudi less prominent tubercles. It 

 should be observed that in the full-grown larva of R. astarti; which has the same general colors and 

 markings as H. guttivitta and H. Uundata, and is thus protected, the prothoracic tubercles are 

 absent. 



How to account for the appearance of such enormous horns may be impossible even after we 

 have become acquainted with the early stages of all the allied species, though it should be borne 

 in mind th.-it the young of Citheronia re<i»Iis and Eacles imperial is, as v.-en as Anisota,have nearly 

 as large spines when first hatched. 



Ph7>«.— Body plump; of the same shape as in E. guttivitta. Head full and rounded, with the 

 two parallel ridges between the eyes slightly larger and more prominent than in JI. guttivitta 



