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species noticed so particularly in the Tropics. On February 2nd, 

 1912, he noticed a large Diplopterou hovering over a large 

 ant, as if about to attack it, and the ant seemed prepared to 

 give battle. The wasp discovered his presence and flew off 

 before he could catch it, and thereupon the ant put its head 

 inside the rolled-up leaf on which it had been crawling when 

 threatened by the wasp and dragged out the pupa of a small 

 moth. The ant was secured and the pupa was kept in the 

 hope that the moth would appear, as only one wing-case had 

 been punctured, but on February 7th a Tachinid fly emerged 

 from the pupa. The pupa case of the moth was so transparent 

 that the puparium of the Tachinid could be seen within it. 

 Another possible interpretation of the action of the wasp was 

 that it had discovered the pupa at the same time with the 

 ant. Those preilaceous wasps had a wonderful instinct for 

 discovering the whereabouts of their prey. In t lie course of 

 last year a wasp was seen to alight on a rolled-up leaf 

 containing a larva of the Hesperid Rhojxilocampta forestall, 

 Cram. It bit into the leaf at once, without any preliminary 

 investigation as far as could be seen, and proceeded to drag 

 its victim out through the hole, shifting its grip from time to 

 time bo as to obtain a more convenient hold. 



I'apers. [czziii 



'The Butterflies of the White Nile, a Study in Geo- 

 graphical Distribution," by G. B. Longstaff, M.A., M.D., 

 P.E.S. 



A considerable discussion took place on the subject of Dr. 

 Longstaff's paper. Col. Yekbuky observed that the Desert 

 Region really extended from Oape Verd to Delhi, and 

 thai its insect fauna was much more closely connected with 

 its flora than with its vertebrate fauna. Many of the Pierines, 

 whose larvae fed on desert species of Capparis, were, as Dr. 

 Longstaff had found on the White Nile, abundant where they 

 occurred, but their distribution was patchy. He also observed 

 that the desert fauna was not drawn from one region only, 

 but from all those that surrounded it, and that all became 

 modified on settling in the Desert Region. 



The Hon. W. Rothschild said that he had lately been 



