290 Studies in the Theory of Descent. 



tentacles of which can be suddenly protruded in 

 a similar manner. Adaptive colours and forms 

 combined with certain habits 1 are, however, much 



1 [For cases of correlation of habit with protective resem- 

 blance in larvae, see a paper in " Ann. and Mag. of Nat. Hist.," 

 Feb., 1878, pp. 159, 1 60. Also Fritz Miiller on a Brazilian 

 Cochliopod larva, Trans. Ent. Soc. 1878, p. 223. Mr. Mansel 

 Weale states, with reference to S. African Sphingidtz (Proc. 

 Ent. Soc. 1878, p. vi.), that many species when seized "have 

 a habit of doubling up the body, and then jumping a consider- 

 able distance with a spring-like action. This is especially the 

 case with species having eye-like markings ; and it is probable 

 that if attacked by birds in a hesitating manner, such species 

 might effect their escape amid the grass or foliage." Many of 

 the defensive weapons and habits of larvae are doubtless means 

 of protection from ichneumons and other parasitic foes. In 

 the case of saw-flies, Mr. Peter Cameron has shown (Trans. 

 Ent. Soc. 1878, p. 196) that the lashing about of the posterior 

 part of the body may actually frighten away such enemies. 

 The grotesque attitude and spider-like appearance and move- 

 ments of the caterpillar of Stauropus Fagi are considered by 

 Hermann Miiller (" Kosmos," Nov., 1879, p. 123) to be means 

 of protection from ichneumons. Among the most remarkable 

 means of defence possessed by larvae is that of secreting a liquid, 

 which Mr. W. H. Edwards has shown, in the case of certain 

 North American Lycanidd (" Canadian Entomologist." vol. x., 

 1878, pp. 3 9 and 131 136), to be attractive to ants, who 

 regularly attend these caterpillars, in the same manner and for 

 the same purpose as they do our aphides. The mutual advan- 

 tage derived by the ants and larvae was discovered in the case 

 of Lyccena Pseudargiolus. Mr. Edwards states that the mature 

 larva of this species is singularly free from Hymenopterous and 

 Dipterous parasites : " Why this species, and doubtless many 

 other Lyccence, are thus favoured will, perhaps, in some degree 

 appear from a little incident to be related. On 2oth June, in 

 the woods, I saw a mature larva on its food-plant ; and on its 

 back, facing towards the tail of the larva, stood motionless one 



