PURPLE EMPEROR. 



73 



tiful white band which in ordinary specimens, 

 crossing the middle of the hind wing, extends 

 into the middle of the fore wing : of the five 

 white spots extending in a curve from the 

 costa to the anal angle, one spot only, namely 

 the fourth, is visible ; the two spots near the 

 tip are smaller than usual, the second of the 

 two being lirtle more than a speck ; the costal 

 margin and the tip are strongly powdered 

 with fulvous, and the usual fulvous ring of 

 the hind wing being broken on its lower side 

 extends in a strong fulvous marking over the 

 anal angle : the rich purple shade is spread 

 over the wings as in the ordinary specimens, 

 blended, however, in parts with fulvous. The 

 under side is equally remarkable, though diffi- 

 cult to describe ; the colouring and markings 

 are much confused." 



A very beautiful example of this variety is 

 figured on the opposite page. It is in the 

 cabinet of Mr. Bond, and has been most kindly 

 lent purposely to illustrate this work. 



LIFE HISTORY. Dr. Maclean, to whom I 

 am indebted for the early history of this but- 

 terfly, watched a female deposit two eggs on 

 the upper side of two leaves of. the sallow, or 

 great goat-willow (Salix caprea), on the 16th 

 of July: the EGG somewhat resembles a fossil 

 Echinus which has lost its spines. One of 

 these eggs the doctor took home, and it 

 hatchod on the 25th of July, just nine days 

 after it was laid : the egg left on the leaf 

 where its parent had deposited it, hatched on 

 the 28th of the same month, having been in 

 the egg state twelve days. The little cater- 

 pillars are of a dark brown colour : on the 

 eighth day after being hatched they change 

 their skin, and then are furnished with two 

 horns or processes, attached to and forming 

 part of the head ; and it is curious that now, 

 on the first appearance of these horns, thuy 

 are proportionally larger and longer than at 

 any other period of the creature's caterpillar 

 life, and are evidently, although not deeply, 

 cleft at the tip. With the first change of 

 bkin the caterpillar loses every tinge of its 

 original brown colour, and becomes exactly of 

 the same haie as the sallow-leaf on which it 

 feeds: a portiuu of the leaf is consumed every 



day, but the midrib is left intact; and the 

 little creature, when resting from its alimen- 

 tary labours, climbs to the denuded bristle- 

 like tip of this midrib, and there remains per- 

 fectly motionless, with the anterior extremity 

 raised as we see it in the caterpillars of the 

 privet hawk-moth and the puss moth. Dr. 

 Maclean's caterpillar continued this mode of 

 life until the 15th of November, when it 

 descended from the leaf, and, covering with 

 silk the rind of the twig immediately below 

 the attachment of the leaf, grasped this web 

 firmly with its claspers, stretched itself out at 

 full length, with its horns porrected before it, 

 and thus settled itself down to endure the 

 winter's cold and the winter's storms. This 

 is always the case ; its modus operandi is the 

 same whether in a state of nature or in the 

 vivarium of an entomologist. Instinct, that 

 infallible and inscrutable guide, tells the un- 

 reasoning caterpillar that dehiscence of the 

 leaf-stalk will take place after the first frost, 

 and that the leaf will fall to the ground : the 

 leaf does fall, but not until its falling is a 

 matter of indifference to the caterpillar ; not 

 until the caterpillar has attached itself so 

 firmly to the twig that neither wind nor rain 

 can remove it. In the ensuing spring, the 

 same influences which compel the sallow to 

 throw out new twigs and new leaves also 

 resuscitate the torpid or dormant caterpillar; 

 its eating propensities are aroused, and it 

 feeds greedily until the period of its first 

 metamorphosis has arrived. 



The full-fed CATERPILLAR rests on the sallow 

 leaf in a nearly straight position, holding on 

 by its claspers to a little silken coating which 

 it spins on the under side of the leaf; but 

 when feeding it bends its somewhat obeso 

 body with the facility, and I would almost 

 say elegance, of a slug, but I fear many of 

 my readers will scarcely appreciate the com- 

 parison. When annoyed, it contracts and 

 incrassates its body, assuming a very lumpy 

 appearance : the head is so exactly the same 

 width as the second segment that it appears 

 continuous therewith ; the face is rather flat- 

 tened, and the crown slightly notched, and 

 produced into two slug-like horns, which are 



