28 MEMOIRS OF THE NATION AE ACADEMY OF SCIENCES. 



1. Tliryrrcn f>iriit.—{F\. XXI. fig. 1. see also Kiley's tigiire in Aiiier. Ent., i., IT. 1) ((/) It lives, 

 or at least the examples collected, lived on the hickory. The general hue is a rather dark olive- 

 green, becoming slightly i)aler above, and pale turc[uoise blue around the bases of all the spines. 

 'I'he seven obli(|ue lateral int'raspiracular bands are paler, of a deep pea green, {h) The green- 

 orange form. It lives on the hickory. It difiers from the entirelj' green form in the orange tint 

 on the back of alwlominal segments 1 to S. The lateral oblique bands are tur([u<)ise I)lue, and the 

 blue arotuid the base of the spine is deeper in hue, wliile the ring around the spiracles, instead of 

 being orange-red as in «, is now deep blue. 



2. The hi !(,' and orange fin-iii . — PI. XXII, tig. 1. It feeds on the butternut. The entire ))ody 

 above is turquoise blue, including the olilicjue lateral stripes, which aredeeply shaded on the lower 

 edge. The spiracles are tinged with orange, and there is a patch of orange behind each abdominal 

 .spiracle of the third and fourth abdominal segments. On asking Mr. Vei'rill whether the colors 

 of Ids photographs are not too bright he replies: ''The color, however, is none too bright even 

 on the blue form; in fact, the brilliancy of this variety can hardly be imagined. It is such an 

 intense opalescent blue that it resembles blue enamel more than animal tissue. AVhen the cater- 

 pillars are first secured I always make a hurried water-color sketch to be sure of the exact shade, 

 and if in the photograph the tints are not true thev are touched up by hand." 



The hro'wn form, stage IV. — (PI. XXIII, fig. 1.) A brown form [a) was found feeding on the 

 ash. The ground color appears to be an olive green, with a faint orange tinge shading into a 

 reddish brown. The horns and spines are all dark black brown. The o))iique lateral bands are 

 very conspicuous, and are of a bright olive-green hue. (J>) Tlie pink form (PI. XXII, fig. 2), iilso 

 living on the ash, was in the fourth stage. The body is uniforndy pale reddisli or madder brown, 

 with a slight pink or carmine tinge. The two large dark thoracic dorsal patches instead of being 

 black are deep madder brown; the head, all the legs, both thoracic and al)dominal, and the 

 armature, as well as the suranal plate, are of the same hue as the body. The oblique lateral 

 bands are nuich paler, almost pinkish." 



It would be most desirable that some future observer favorably situated should ascei'tain the 

 exact conditions of the environment under which these colored forms have been produced, how 

 permanent tliey are, and whether hereditary or only confined to the lifetime of the individuals 

 fheniscdves. 



In is;t2 Professor Poulton'' studied experimentally the adjustment of tiie colors of the larvffi 

 of Am jih /'(lasts hetidarta to those of their environment, and in 1903'' he published the results of 

 experiments on another geometrid larva, (hlontopera hidentdta. This larva is extremely sensi- 

 ti\c. with a power of adjustment about e(iual to that of the .\mphidasis. "'the most sensitive 

 larva liitherto known." A large numl)er of records proves that the larva?, in the great majority 

 of cases, rested by day upon the olijects, lichen-covered twigs, whose hue they afterwards came 

 to resemble, tiiough this is "probably not the case in the earliest stages, when the larv» doubt- 

 less rest on the leaves and stalks." "The etl'ect of green leaves alone upon hldentata is the same 

 as that observed in many other larva'. Nocture as well as Geometrsv, viz, the reduction of the 

 brown ground color to a very pale tint which would be far less conspicuous than the more ordi- 

 nary appearance." 0. hldentata appeared to be more sensitive to lichen than .1. hetularia, but 

 less sensitive to green leaves, though the two species are "about equal in the power of color 

 adjustment." And Poulton adds, "lichen nuist have been the cause of the hetularia larva>, with 

 one exception, becoming green, for ordinary bark tends strongly to the production of dark forms 



« From Mr. Verrill I have also received colored photographs of a green and of a pinkish form of Ampelophaga 

 rnijron on the grape vine; also of the red form of Cressonia juglandis, and a red form of Apaieta hruDiosa. 



'• Further experiments upon the color relation between certain le])idopterous larvpe, pupse, cocoons, an<l iiiuigiiies 

 and their surroundings. Trans. Fnt. Soc. London, Dec, ]cS92. 



''Experiments in 1893, f894, and 18(16 upon the color relation between lepidojiterous larvre and their surround- 

 ings, and especially the effect of lichen-covered bark upon Odontopera bidentala, Gastropaclta guerdfotia, etc. Ibid., 

 Oct., 1903. 



