118 BRITISH BUTTERFLIES. 



almost as effectively concealed as the former. When walking, the 

 larval movements are particularly slug-like, the little black head pressed 

 down to the surface on which the larva is walking, and quite hidden 

 when looked at dorsally, the prothorax forming as it were the front 

 part of the gliding larva which moves along fairly rapidly, yet with 

 scarcely any perceptible muscular movement, except a slight working 

 from side to side as the forward movement is made. When, however, 

 a break in its path occurs, the head is thrown up, the pro- 

 thorax much narrowed and extended to its full length, the 

 head turned from side to side in an enquiring way, and stretched 

 to its farthest limits, until the further forward progression of 

 the larva is assured, and, at this time, its lengthened body has quite 

 a different appearance from that of its stumpy body when at rest or 

 moving slowly, and without need to discover its whereabouts. Looked 

 at sideways, its movements are very interesting, the anal prolegs being- 

 placed some distance beneath from the extreme end of the body, raises 

 it naturally from the surface, and, when movement takes place, a sort 

 of wave passes along the larval body. The true legs appear to be 

 kept continuously in motion, but this is not so, and the forward move- 

 ment of the prolegs is in series, the anal prolegs being pushed forwards 

 a step, followed directly in order by the fourth, third, second, and 

 first prolegs, and then by the third, second, and first true leg.-, a wave 

 as it were pulsing along the segments as each pair of prolegs is pushed 

 forwards, and takes a fresh hold, the anal segments being continuously 

 lifted up and down as it were, as the anal prolegs take a grip forwards, 

 and are immediately, as the motion is transferred to the pair of prolegs in 

 front, lifted again, to be as quickly pushed forwards, so as to get a fresh 

 grip, and start a fresh series of forward undulations. When a larva 

 is coming from a calyx-tube head-first, it projects its head as far as 

 possible, and uses its prolegs, with a sort of screw movement, to wriggle 

 the front segments out of the hole thus formed, a hole apparently very 

 small, and out of all proportion to the size of the body ; when, how- 

 ever, its front segments are free, it bends down and uses the true legs 

 in order to cling to the outside of the calyx, and soon levers the rest of 

 the body outside the hole. The larva makes excellent use of its silk- 

 spinning power. It falls at the least disturbance, doubles itself up ven fcrally, 

 and remains for a time quite immovable, and then, pushing forwards 

 its head as far as possible, attempts to get a grip with its true legs, 

 and slowly rolls itself over. The power of hanging by an almost in- 

 visible silk thread makes it sometimes appear to undergo many strange 

 evolutions, of which the ability to stand with its back to the resting- 

 surface and its legs in the air, and then slowly change its position 

 and bring its legs back to the resting - surface, and go on crawling, is 

 one of the most peculiar, for the silk that supports it and 

 enables it to do this is quite invisible. The larva- crawl 

 about over each other with no apparent harm, no notice being, 

 as a rule, taken, though occasionally one notes a badly-bitten 

 example when many are kept in close quarters in confinement, 

 but one suspects that this is done when the victim is partly buried in 

 a flower, and a friend, utterly oblivious of its presence, buries its jaws 

 into the immobile larva instead of the flower it supposes should be 

 there. A larva can cross any distance it can possibly reach with its 

 mouth, spinning a second silken bridge that it walks over, in slow and 

 approved manner. This movement is, for the size of the larva, 



