460 Mr. G. A. K. Marshall on 



or pseudaposematic ; certain stages in the life of an indi- 

 vidual may be cryptic, others aposematic or pseudapo- 

 sematic. There is nothing subversive in the thought that 

 certain species exposed to dilferent organic environments 

 in two seasons of the year may appear as cryptic genera- 

 tions at one of these, aposematic or pseudaposematic at 

 the other. The explanation is at any rate sufficiently 

 probable to enable us to contemplate Mr, Marsliall's wonder- 

 ful discovery with equanimity and with an interest un- 

 disturbed by the thought that he has laid in ruins the 

 whole edifice of insect systematics. 



20. The Gregarious Instinct in Hybernation and 

 Emigration of Insects. (E. B. P.) 



The interesting observation that individuals of Precis 

 scsamus are apt occasionally to congregate in large numbers 

 as they go to roost, led me to reflect on the possible 

 meaning of such an instinct. Mr. Marshall records other 

 examples of the same kind " in species of Euralia, also 

 in Belcnois, Herpienia criphia, an^l Teracohis eris " (Ann. 

 and Mag. Nat. Hist., loc. cit., 1808, p. 34). It is possible 

 that one interpretation does not explain all these cases, 

 but I think it is probable that the observed instances of 

 the congregating of Precis and Euredia are sporadic ex- 

 amples of an instinct which is associated with hybernation 

 or, at any rate, a prolonged period of rest during a time of 

 relatively excessive cold, heat, or dryness. Objection may 

 be taken to this interpretation on tlie ground that large 

 companies undergoing a ]3rolonged rest ought to be well 

 known in these species. It is possible however that the 

 extreme conditions which render such a state desirable 

 or even necessary for the species are not common, and, 

 when they occur, do not conduce towards the active pursuit 

 of natural history; furthermore, such j^rolonged rest would 

 probably be passed through in some hidden recess which 

 could only be found by accident. 



Large numbers of naturalists for hundreds of years have 

 been interested in the doings of Vanessa io, but, so far as 

 I am aware, it is not generally known that this species 

 may display a gregarious habit in hybernation.* My friend, 



* Edward Newman recorded the occurrence of a company of more 

 than forty V. io in a hollow oak (British ButterHies and Moths, 

 London, N.D., p. 16), and the Rev. Joseph Greene disturbed three 



