422 LÉPIDOPTÉROLOGIE COjMPARÉE 



caused by the unequal parts the characters of the two parents 

 hâve played in determining the appearance of the caterpillar. 

 Owing to the fact that the larva is closest to sonaria, the gênerai 

 course of the variation is necessanly toward pomonaria. 



The fi.rst great point is the change in the texture of the skm, 

 which in helenœ and sonaria is very hne. Several of my spéci- 

 mens of helenœ were quite as coarse in the skin as in pomonaria, 

 and this was accompanied, for the most part, by an extraordi- 

 nary degeneration of the markings and by a change toward 

 yellow in the colour of the ground. 



The other features of the variation, in the examples with the 

 usual type of skin, are toward the appearance of the suffusions 

 near the band and yellow spots, exhibited by pomonaria. This 

 results, in extrême cases, in the production of the curious dorsal 

 pattern mentioned in the cases of denhami and pilzïi. The two 

 black tubercles, too, may be quite as large and black as in pomo- 

 naria. 



Of course, in other examples, as there is still scope left for 

 variation toward sonaria, there is that tendency shown in the 

 broadening of the spiracular line, the darkening of the ventral 

 area and a very pronounced détérioration in the structure of the 

 longitudinal stripes. 



Habits of larvae. 



Thèse larvae, though they adopt the food plants of pomonaria, 

 and reject those of sonaria, are much nearer the latter species in 

 habits. When feeding, in their young stages, they wander about, 

 eatmg little scraps hère and there ail over the leaves, and spinning 

 much silk. As they grow older, they demolish the leaves wholesale 

 and seem very ravenous. They feed chiefly at night. Even when 

 in the last instar, they stick much less to the food than denhami 

 larvae do. When sleeved on a branch of hawthorn they seem to 

 hâve no fixed resting place but rest indiscriminately on the twigs, 

 or on the muslin sides of the sleeve. This habit caused me to lose 



