326 Professor E. B. Poulton on colowr-relation 
darkness follow in the same order as that in which the 
results are recorded, except that V and VA were much 
alike, the brown differing in tint rather than in depth. 
VI were much lighter than any of the others. 
B. LIGHT LARVZ OF BIDENTATA ON JULY 6TH. 
VII. Weathered grey barkless twigs—The larvee were 
very light; of a distinct grey colour, harmonizing perfectly 
with the environment. 
VII. Green leaves and shoots of food-plant—The 14 
larvee were all very light brown but not at all greenish. 
IX. Orange paper spills—The 15 larve closely re- 
sembled VIII, but were not quite so light. . 
Some of the results of this comparison have been 
incorporated in the tabular statement. Another careful 
comparison was made on July 27th, but in this case it 
was possible to include the whole in the table. 
SECOND EXPERIMENTS WITH LARVA OF O. BIDENTATA. 
EXPERIMENTS WITH LICHEN ON LARVZ OF 
A. BETULARIA (1898). 
In sending the second mixed set of eggs of bidentata, 
Mr. Porritt wrote on June 18th, 1893—“TI certainly had 
no expectation of seeing any more Odontopera bidentata 
this season. However, when collecting on Saturday, at 
Sledmere, in a high wood on the Yorkshire Wolds, I found 
several! ‘Two of the females have deposited a few eggs, 
which I forward at once with this. Sledmere is on the 
chalk, and bidentata there is quite of a different type to 
our West Riding moth, being of the pale, ochreous banded, 
distinctly southern form.” 
The eggs were placed in a single cylinder, and as soon 
as a sufficient number of larvee had hatched, I started 
Experiments X to XV, between June 27th and July 3rd, 
the 14 larvee of A. betwlaria received from Mr. Arthur 
Sidgwick being divided between Experiments XII to XV. 
Experiments XVI to XVIII were started on August 3rd 
by Mr. Holland, with the latest larvae of didentata. All 
the observations on Experiments X to XVIII recorded 
in the tabular statement on pages 328—331 were made by 
Mr. Holland. The food-plant used throughout was Populus 
nigra. When flat pieces of bark were introduced (XII, 
