326 Professor E. B. Poulton on colour-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 LARV^ OF BIDENTATA ON JULY 6tH. 



VII. Weathered grey harJdcss twigs. — The larva? were 

 very light ; of a distinct grey colour, harmonizing perfectly 

 with the environment. 



VIII. Green leaves and shoots of food-plant. — The 14 

 larvae were all very light brown but not at all greenish. 



IX. Orange paper sinlls. — The 15 larvae 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 Larv^ of O. bidentata. 



Experiments with Lichen on Larv^ of 



a. betularia (1893). 



In sending the second mixed set of eggs of bidentata, 

 Mr. Porritt wrote on June 13th, 1893 — " I certainly had 

 no expectation of seeing any more Odontopera bidentata 

 this season. However, when collecting on Saturday, at 

 Sled mere, 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 hidentata tliere 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 larviu had hatched, I started 

 Experiments X to XV, between June 27th and July 3rd, 

 the 14 larva3 of A. hetidaria 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 hidentata. 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 Popnlus 

 nigra. When flat pieces of bark were introduced (XII, 



