hehoeen lepidoiyterous larvm and their surroundiiu/s. 313 



they afterwards came to resemble. This, however, is pro- 

 bably not the case in the earliest stages, when the larvse 

 doubtless rest on the leaves and stalks. 



The extreme sensitiveness of this larva is clearly shown 

 by a glance at Plate XVI. The four first figures indicate 

 a power of adjustment about equal to that of the most 

 sensitive larva hitherto known, Ampliidasis hctularia (com- 

 pare Trans. Ent. Soc. Lond., 1892, Plate XIV). The effect 

 of green leaves and shoots, shown in fig. 5, is however 

 very inferior to that produced upon hctularia, which 

 becomes brigrht green in this environment. The effect of 

 green leaves alone upon hidentata is the same as that 

 observed in many other larvse, Noctuse as well as Geometrse, 

 viz, the reduction of the brown ground-colour to a very 

 pale tint which would be far. less conspicuous than the 

 more ordinary appearance. The contrast between the 

 results of an effective environment of green, and nothing 

 but green, as shown in fig. 5, and of green scattered over a 

 brown background of bark, as shown in figs. 6 to 11, is very 

 striking, and suggests renewed experiments with an artificial 

 arrangement of combined colours. Another interesting fact, 

 suggesting the restriction of larval susceptibility to the 

 immediate surface upon which the resting periods are 

 passed, is the entire absence of any effects traceable to the 

 green leaves of the food-plant when present with the 

 other forms of environment employed in these experiments. 

 The complex nature of the result produced is well seen in 

 the oblique white lateral marks which are found in larvse 

 with the green lichen-like patches (figs. 6, 9), and probably 

 assist in the general effect by breaking up the larval 

 surface. The green markings are developed in the vicinity 

 of and include the projecting ridges, etc.— a fact which 

 is of obvious significance in promoting the resemblance 

 to small scattered masses of lichen. The various kinds 

 of lichen made use of did not produce corresponding 

 effects.* Thus the green dorsal patches shown on the 

 larvffi which had been exposed to orange lichen (figs, 8, 

 9) did not differ in any marked degree from those in 

 which a green lichen had been chosen. It is by no means 



* My friend Prufessor S. H. Vines, F.R.S., has very kindly .ijiven 

 me the probable names of the lichens made use of. They will be 

 found in the detailed account of the experiments, and in the 

 description of Plates XVI to XVIII. The names could not be given 

 with certainty because the specimens themselves had been lost. 



