METAUOEPHOSIS IN LEPIDOPTEEA. 17 



more or less exposed life, and their changes (correlated with their 

 habits) are so fixed that the plumage is often sufficient to discover the 

 instar already reached by an individual larva. Chapman has given 

 (ante, pp. 12 et seq.) some remarkable details bearing on this point with 

 regard to Notolophus antiqua, Joclieaera alni, Arctia caia, &c. It often 

 happens that the larva3 of two species are quite unlike when adult and 

 yet present great similarity in their earlier stages. It has also been 

 observed that one or more of the ea"rly larval stages of a species may 

 sometimes closely resemble the adult stage of another. Such simi- 

 larities as these have been frequently noticed, and, as the resemblances 

 clearly point to a common origin, whilst the differences tend to show 

 the point at which divergence has arisen, the phylogenetic significance 

 of such markings may prove of the utmost importance. Interesting 

 deductions in this direction have been made by Poulton and others on 

 the phylogeny of certain Saturniid and Sphingid moths. 



Scudder applies the term " hypermetamorphosis " to the changes 

 observable in the external character of the larva and the variable 

 nature of the segmental appendages, at each larval exuviation. He 

 notes that the mature larvae of Satyrids have a rough skin due to a 

 vast number of minute tubercles, each bearing a single hair and 

 scarcely visible to the naked eye. The skin of the young larva, how- 

 ever, instead of being thus supplied, bears only a small number of 

 club-shaped bristles, arranged in the characteristic longitudinal series 

 of tubercles. In Nymphalidi the newly hatched larvae bear regular 

 stellate warts, whilst, in the mature larvae, some of the segments 

 are provided with fleshy tubercles, in place of the warts, and some of 

 the segments themselves are grotesquely and peculiarly hunched. In 

 Anoxia archvppm the young larva is ornamented only with black bristles 

 placed on the ordinary trapezoidal tubercles, whilst the adult possesses, 

 in their stead, long thread-like fleshy flexible tentacles at each 

 extremity of the body. In Vanessids the young larvae have long 

 tapering hairs arranged in ordinary form, whilst these are replaced in 

 the adult larva by conspicuous branching spines. In the Heliconiids, 

 the newly-hatched larvae have large tubercular papillae, each bearing 

 a long slender clubbed hair, but after the first change of skin the head 

 is armed with a pair of stout thorny spines nearly as long as itself, 

 whilst the large papillae are replaced by tall tapering spines bearing 

 little needle-like papillae, the differences being intensified at every 

 subsequent ecdysis. 



Clifford and Moncreaff both give three as the normal number of 

 moults in Smerinthus ocellatus and 8. fopuli. Moncreaff further 

 observes that, when moulting, the old cap (or head) of the larva is first 

 thrown off and that the skin then breaks up between each segment and 

 along the spiracles. He further states that three-fourths of the young 

 larvae of these species perish in their first moult, not being able to rid 

 themselves of the old head-covering. Bacot states that the larva of 

 S. ocellatus ha,s four moults (not three). Miss Golding-Bircl also notes 

 that the " mask," or old head, is first moulted and falls from the larva 

 of Stauropus fagi before the further moulting has seriously commenced. 



Many green tree-feeding larvae that pupate in the ground, and 

 have an intermediate period of wandering on the ground, are well- 

 known to assume various colour changes between the time that they 

 leave the food-plant and that at which they undergo pupation. This 



