Certain Forms of the Genus Acraea. 293 



many of the smaller Acraeas the sphragis is not or scarcely 

 at all developed, vet in these the uncus is in proportion 

 to the claspers, very large and well developed. 



In one or two places Professor Houlbert suggests that 

 he has had some difficulty in making out the structure ot 

 the genital armatures owing to their desiccated condition. 

 Should he continue his investigations, and I sincerely hope 

 he will do so, he will find that if the terminal segments ot 

 the abdomen are boiled in caustic potash (KHO) tor a 

 minute or two all extraneous matter is easily removed, and 

 the specimen can be dehydrated, cleared in clove oil, and 

 mounted in Canada balsam in a cell so that it is not com- 

 pressed He will then find that the organ can be examined 

 under the most favourable conditions, and its form easily 

 made out with the help of the stereoscopic microscope. 



If he will submit a sphragis to the same treatment he 

 will find that it disintegrates and dissolves with great 

 rapidity, conclusive evidence that it is of an entirely 

 different chemical constitution from that of the organs 

 to which he would seek to ally it. 



Following on this discussion of the armature and sphragis 

 generally, M. Oberthiir contributes interesting details con- 

 cerning some of the less-known Madagascar Acraeas He 

 points out an error in my account of Acraea igati, which 1 

 stated to occur only in Madagascar, whereas he has examples 

 from Aniouan and Grand Comoro. I was of course, 

 unaware of this when my paper was published. A. damn 

 and A. fornax are dealt with, and finally the author gives 

 a comparative study of A. strattipocles, A masamba, and 

 a form to which he gives specific rank, A. siliana. M. 

 Oberthur's discussion of these forms is a most useful 

 addition to our knowledge. With characteristic generosity 

 the eminent French naturalist has presented to the Hope 

 Collection at Oxford beautiful series of several Madagascar 

 species of Acraea. Amongst these are a number of examples 

 labelled masamba and some labelled silia M. Oberthur 

 now finds that the latter do not in reality correspond 

 to Mabille's var. silia, but are in fact an undescribed form 

 which he regards as a good species, and for which he pro- 

 poses the name siliana. Furthermore, he declares his 

 inability to distinguish the species of Acraea to which 

 Mabille's PI. 9, fig. 1, la (masamba) and fig. 3 (var. silia) 

 belong A. strattipocles is dealt with in the same section 

 of the paper, but as there is no difficulty in identifying 



TRANS. ENT. SOC. LOND. 1916.— PART II. (DEC.) U 



