LIPE-HISTOR.Y OP THE LADY-BIRD liRETLE, 487 



and Red diflering thus in degree of pigmentation. But those 

 Red forms, in which the black spot even stretches as a hand across 

 the elytra, do not necessarily have a more pigmented pronotum 

 than in "type." If an increase in the size of the hlnek spot of 

 •' type'" means a step forward in a melanistic direction, one would 

 expect this tendency also to aft'ect tlie pronotum. 



C variahilis. 



C. variahilis has two forms of imagines, which in general 

 colour arrangement are similar to the two principal forms of 

 A. bipvnctata. There is a Black form with ten red-ochreous 

 spots and a Red (ochreous) form with fourteen black spots. The 

 difference in the shade of the red between the two forms is 

 much more marked than in Adalia. The red spots on the Black 

 frequently tend to carmir^e at the edges, but the red ground- 

 colour of the Red form would more accurately be described as 

 ochreous; it is never as deep a red as occurs in A. bipunctata 

 (type). I have no information of tlie percentages in which these 

 types occur. The Black form of variabilis is the " type,"' but 

 whether this indicates that it is the more common is unknown. 



The dimorphism in bijnmctata and variabilis is not equivalent 

 to that of Lina (18), in which there is a spotted and a melanic 

 form, for in that species there is certainly only one colonr-pattern, 

 as the spots can be sometimes seen in the melanic form by 

 holding the wings up to the light. MacOracken (18) found the 

 melanism recessive. 



Two matings of va7-iabilis w eve made: (1) mating 17, c? Black 

 X 2 Red produced 4 Red imagines ; and (2) mating 18, c? Red 

 X 2 Black produced 4 Black and two Reds. As in bipii, aetata, 

 there is no sign of dominance. 



A third mating (10) was made between a S Red bipunctata 

 and a § Black variabilis, the result of which was 7 Red variabilis 

 and 5 Black variabilis. The two mated at intervals from 

 May 29 to June 26, and during that period laid eggs as follows : — 

 15 on June 3, 16 on June 4, 24 on June 12, 6 on June 18, and 

 15 on June 26 ; a total of 76. As the results Avere all variabilis, 

 one cannot but suppose that the female was satisfactorily ferti- 

 lised by a male of her own species before she was caught. This, 

 however, involves the necessity that some of the spermatozoa 

 remained capable of fei-tilization for 29 days at least ; but Palmer 

 states, p. 235 (21) : "A female Adalia would not seem to be able 

 to lay fertile eggs for more than tln-ee weeks after being isolated 

 from a male." 



On one point these two species differ considerably, for it is the 

 Black form of bipunctata which is tlie more variable in the 

 numbei- of spots, whilst in variabilis it is the Red form which 

 is the more variable. The I'ecuri'ence of the same type of 

 variation in species so nearly related and which constantly occur 

 together, makes an understanding of the one imperative to a 

 satisfactory understanding of the other. 



