ON THE FEMALE POUCH IN ACRiEA. 73 



most striking. Two days ago there were thousands on the wing 

 round the lucerne flowers ; to-day a few solitary specimens were 

 all that remained. 



This concludes my collecting during the manoeuvres. Except 

 for the last week at Sheerness, which yielded twenty species of 

 butterflies, there were few opportunities of collecting, if we omit 

 Tinea biselidla, which was only too abundant on board ! It is 

 evident that 1900 will long be remembered as " the great Colias 

 year," but I do not recollect having seen in the magazines any 

 previous record of either species from Sheppey. 



H.M.S. ' Gladiator,' Mediterranean Station. 



ON THE FEMALE POUCH IN ACRMA. 

 By Guy A. K. Marshall, F.Z.S., P.E.S. 



In the November issue of the ' Entomologist ' Dr. Chapman 

 raises an interesting question as to the significance of the curious 

 anal pouch which is found in the females of Parnassius. It 

 may therefore be as well to record the fact that a similar struc- 

 ture occurs in the females of Acrcea, these being, I believe, the 

 only two genera of butterflies which exhibit this peculiarity, and 

 it seems at least probable that it may serve the same purpose 

 in both cases. 



A year or two ago, when writing to me on this subject, 

 Professor Poulton suggested that possibly the structure might be 

 of use in guiding the egg during oviposition, or even that the 

 egg might be carried in it until a suitable place for it had been 

 found. Therefore, in order to obtain some evidence for the 

 former proposition, I carefully watched several examples of 

 Acrcea caldarena and A. nohara-halali during the act of laying 

 their eggs. As a result of this I found that the egg, on extru- 

 sion, did not in any way come into contact with the pouch, this 

 latter being placed too much upon the ventral surface of the 

 abdomen to render it of any use for the purpose of oviposition. 

 Indeed, in some cases it appeared to be rather an obstruction 

 than otherwise, for in the food-plant of these Acracs the sides of 

 the leaves sometimes fold together rather closely, and more 

 than once I have seen a female trying to insert her abdomen in 

 such a place, but prevented from doing so by the projecting 

 pouch. 



Again, both the position and construction of the pouch 

 render it highly improbable that it can be used for the purpose 

 of transporting the eggs, and although I have caught some 

 hundreds of the insects at various times, I have never yet found 

 this to be the case. 



