IN DEFENSIVE COLORATION 301 



shadow. Many years ago I observed a Green Hair- 

 streak Butterfly (Thecla rubi), which, when it settled on 

 a leaf, let itself down on one side so completely that it 

 seemed to lie flat on the surface. The obliteration of 

 shadow was very marked, and forced itself upon me at 

 the time as the significance of the attitude. 1 

 ,^-4. The Choice of Appropriate Surfaces upon which 

 ,^0 Rest.— Dr. F. A. Dixey 2 and Mr. A. H. Hamm 3 have 

 produced evidence which suggests that the Small 

 Garden White, Pieris rapae, tends to select white sur- 

 faces upon which to rest for the night. An observa- 

 tion made by Dr. T. A. Chapman 4 upon Colias edusa 

 supports this conclusion. Dr. Dixey and Dr. Longstaff 

 have observed an analogous instinct in Eronia cleodora 5 

 in South Africa, and have published many records of 

 similar observations on other species. 6 Mr. Hamm's 

 records 7 and photographs of British moths in their 

 natural attitudes of rest on bark or stone also show 

 the same co-operation of appropriate instinct with a 

 Procryptic colouring and form. The manner in which 

 one of the moths observed by this keen naturalist brings 

 the main lines of its pattern into parallelism with the 

 main lines of shadow in its immediate environment has 

 already been described on p. 156. 



5. The A 11- Importance of Instinct in Bringing About 

 Protective Resemblance. — The appropriate instincts form 

 probably the most important and essential element in 

 Procryptic Defence. Several examples have been given 

 in the two preceding paragraphs, and many others will 

 be found on pp. 154-66 of the present work, where it 

 is shown that the appropriate actions are performed 



1 Proc. Ent. Soc, Lond., 1906, p. xxviii. 



2 Trans. Ent. Soc, Lond., 1906, pp. 116-17. 

 9 Proc. Ent. Soc, Lond., 1904, p. lxxv ; Proc. Ent. Soc, Lond., 1905, 



p. lxxiii ; Proc. Ent. Soc, Lond., 1906, pp. c, ci. 



* 1. c. 1905, p. lxxv. 



8 Trans. Ent. Soc, Lond., 1906, pp. 1 13-14; 1907, pi. xxv. 



8 See Longstaff in Trans. Ent. Soc, Lond., 1906, pp. 11 3-1 7. A large 

 number of Dr. Dixey's observations are recorded in this paper. See 

 Dixey in Proc. Ent. Soc, Lond., \ 906, p. xxix. 



7 Trans. Ent. Soc, Lond., 1906, p. 483, pi. xxix. 



