594 Notes in 1887 upon lepidopterous larve, de. 
base of a catkin; the short stout body of the larva is of 
the appropriate shape and size, and is held in the 
appropriate attitude; the edges of the segments, seen 
in profile, project a little, and are very distinct all round 
the larva, thus suggesting the overlapping scales of the 
catkin ; and the resemblance is heightened by the pro- 
jecting edges being tipped here and there with brown, in 
the green larve. The brown larve similarly resemble 
the older brown catkins. 
There is some evidence for the appearance of these 
varieties at slightly different times, corresponding to 
changes in the colour of the catkins, but confirmation 
is needed before this can be accepted as proved. Of 
12 larve sent me, in the spring of 1887, by Mr. W. H. 
Harwood, about half were green, and the rest brown: 
the former pupated much earlier, while the latter lived 
on until the birch-catkins were brown, and then died 
before pupation. The evidence suggests that observa- 
tions should be directed to this point, and that large 
numbers of larve should be employed. Unfortunately 
my experience this year (1888) did not much help 
matters, for there was only a single brown larva, and in 
this case no difference was observed between the times 
of maturity in the two varieties. Mr. Harwood informs 
me that he has not observed such differences, but that 
he believes the larve on hazel are somewhat different in 
appearance from those on birch. My own experience 
is limited to the latter food-plant. 
The protective methods of this larva seem to be very 
remarkable, and to call for further observation. 
11. A PROOF OF THE PROTECTIVE VALUE OF DIMORPHISM 
IN LARVH.—Whatever be the value of the dimorphism of 
the older larve of Geometra papilionaria, it is quite 
certain that this mode of appearance is useful to the 
species. From the pupe obtained from green larve in 
1887, moths were bred and fertile eggs obtained: about 
30 young larve grew up to maturity, and of these only 
a single one was a brown variety. If, therefore, either 
of these varieties had any advantage over the other, and 
continued to have advantage, whatever the proportionate 
numbers might be, it is quite clear that such variety 
would very soon be the only one. The fact that both 
varieties exist, demonstrates that the dimorphism is 
