Memoirs of the National Academy of Sciences . kings on the thoracic segments and on the third andfourth and on the fifth ami sixth abdominal segments, these bright spots becoming somewhat less•decided and conspicuous in the final stage. Fig. 1 (p. 37) represents the first larval stage of H. oUiqua, its horns being like those of H. gut-iivitta (III«), and also dropped at the first molt. MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 37 Now, it seems uatural to suppose tbat the disappearance of the armature of this iusect withthe fust molt was due to the hick of need for it by the caterpilhir, wli
Memoirs of the National Academy of Sciences . kings on the thoracic segments and on the third andfourth and on the fifth ami sixth abdominal segments, these bright spots becoming somewhat less•decided and conspicuous in the final stage. Fig. 1 (p. 37) represents the first larval stage of H. oUiqua, its horns being like those of H. gut-iivitta (III«), and also dropped at the first molt. MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 37 Now, it seems uatural to suppose tbat the disappearance of the armature of this iusect withthe fust molt was due to the hick of need for it by the caterpilhir, wliieli gradually became adaptedto a Ufe on the underside of an oak leaf, where it assumed a simple spindle-shaped body extendedwhen at rest along the midrib, in which position we have found the older caterpillar, its bodyjilaucons-green and so marked with yellowish lines and reddisli spots, as well as with dashes andlines, as to be wonderfully assimilated to the greenish, reddish, and whitish hues of the leaf under?which it was Fig. 1.—Early stages of Jletei-ocaiiiva obUqxta and H^guttivitta.—I. Reterocavipa ohliqna Pack—Freslily batched larva; 7a, dorsalvie^w; 1 b, spine on third ; Ic, spine on i-ighth ; Jd, spine on ninth abdominal segment; le, prothoracic horns of stage I, enlarged. II. Hetero-ranipa obliqua Pncit.—Stage II; Ila, horns on first prothoracic segment. III. lletemcampa guttiritta TTaU-.—Horns in stage I; a, pro-thoracic hum; h. one on second abdominal; c, one on third to fifth, and (?, on ninth ;ibdominal segment. (The seta; are in some cases omitted). It also seems reasonable to suppose that these adaptational, colorational features were acquiredby the ancestors of the present forms during the different stages succeeding the thus we are warranted in assuming that this and multitudes of other cases of adaptation tothe change in habits and modes of life and special situations were acquired originally, at differentperiods
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