on Milllerian Mimicry and Diaposematism 579 



statement above quoted a more special application by 

 instituting a comparison between the under side of P. 

 locusta $ and the cydno group of Heliconius ; even then 

 being careful to point out that " the aspect suggested [by 

 P. locusta $ underside] is rather that of several forms of 

 Heliconiiis in general than that of any one in particular." 

 Why Mr. Marshall should think it necessary to show that 

 the upperside of P. locusta $ is non-mimetic " and can 

 have no significance during flight" (p. 113) I am at a loss 

 to understand, for I myself expressly stated that " it is 

 only on the underside that the mimetic pattern appears, 

 and here again there can be little doubt that its use has 

 reference only to the resting position." Mr. Marshall 

 appears to disbelieve that any mimetic significance what- 

 ever attaches to either surface of the male P. locusta. In 

 this opinion I think few impartial observers will follow him. 

 With regard however to the "fair general resemblance" 

 which he admits to exist between tlie upperside * of the 

 female of P. locusta and the gcdanthus form of H. cydno, 

 he arrives at the conclusion " that the most satisfactory 

 interpretation of the present case is that the ^ Pieris is a 

 simple Batesian mimic of the Heliconius.'" In support of 

 this position he makes some remarkable statements. " It 

 is only fair to point out," he says, " that when this pro- 

 posal " [i.e. my suggestion as to the association of P. 

 locusta with the cydno group] " was made, the true $ of 

 P. locusta was not known, the ^ figured by Dr. Dixey 

 belonging really to P. tithoreidcs, Butl." I regret to have 

 to correct ]\Ir. Marshall on a point of fact, but he will find 

 on further enquiry that the female of P. locusta was then 

 known and had been described by Felder. I figured the 

 local race (or geographical species) tithoreidcs under the 

 designation of the type form, for the simple reason that 

 there was then no other name by which to call it, its 

 present title not having been bestowed upon it until some 

 time later.-]- I do not know on what grounds Mr. Marshall 

 pronounces P. locusta $ to be " evidently a rare insect." 

 Folder's account X implies that the species is common. I 

 can of course readily believe that the male falls a more easy 

 prey to collectors. 



* Wh}' not also the underside ? Can it be because this would 

 carry a similar conchision in the case of the male ? 



t F. tithoreides was first described by Butler, Ann. Mag. Nat. 

 Hist, 1898, ii, p. 18. 



X Reise d. Novara ; Ehop., p. 176. 



TRANS. ENT. SOC. LOND. 1908.— PART IV. (jAN. 1909) 38 



