African S2')ccics of the Genus Acraca. 9 



is only during this last season that I have been able to 

 inquire into its origin. By pressing the abdomen of the 

 Acraea males, one can force out from under the posterior 

 margin of the last dorsal plate a very large gland, which 

 is entirely similar to that which the females of the 'Mara- 

 cuja butterflies ' {Hcliconms, Eucidcs, Colaenis, and Dionc) 

 exert at the same spot when seized. This gland is some- 

 times bare, sometimes covered with brown or blackish 

 scales and liairs, which fall off at the slightest touch. The 

 appendage of the female, when treated with hot soda-lye 

 and crushed between glass plates, proves to be composed 

 of hairs and scales of the same form. Among hundreds of 

 males which I examined for this purpose, almost all showed 

 the gland either entirely covered or entirely bare : twice only 

 I found the hairs stuck together in small isolated patches, 

 and twice joined together in a structure similar to the 

 female appendage but thinner and more fragile. Probably 

 in the act of pairing one of the sexes emits a rapidly drying 

 fluid which gives it the subsequent thickness and solidity." 



At one time I hoped to find in Acraea some correlation 

 between the inequality of the male tarsal claws, and the 

 occurrence of the sphragis in the female. I find however 

 that in some species in which the male claws are unequal, 

 the spliraijis is not formed in the female, at least so far as 

 I am able to judge from the extensive material which has 

 been at my disposal. I have examined the claws in the 

 other genera mentioned, and find that whilst the male 

 Pnrnassius has unequal claws, those o^ Eurycus, Euryades, 

 and Amauris are equal. Thais has only a slight develop- 

 ment of the sphragis, and has unequal claws in the male, 

 whilst the genus Doritis has unequal claws in the male, 

 but I can find no secretion in the female. 



The peculiarity of the male tarsal claws is one to which 

 I am still unable to assign a satisfactory explanation. The 

 few species of the genus which liave the claws equal, do 

 not present any other feature which would serve to sepa- 

 rate them, however slightly, from the remaining members 

 of the genus. Moreover if, as seems inevitable, we are to 

 regard all the examples of the servona form as of one 

 species, we have in this one case an instance of unequal 

 claws appearing occasionally as a reversion, in a species in 

 which the claws are normally equal. 



Whilst the meaning of this structure must for the 

 present remain unexplained, a knowledge of it is of 



