'2'3'2 Proceedings of the Royal Physical Society. 



muslin cover. The confining of the larvte to a small quantity of soil served 

 two purposes. It enabled their movements in the soil to be observed 

 through the glass, and it limited the amount of soil to be searched in the 

 event of the maggots leaving their hosts on pupation. 



On the following morning (23vd April) it was found that the maggot 

 removed and preserved in the petri dish had pupated. The pupa is reddish 

 in colour, barrel-shaped, about 4 mm. long. 



On the 26th April the contents of the glass vessel were examined, and 

 this time only apparently healthy larvae were found living. The decom- 

 posing remains of two larvae were also found, which were manifestly two 

 of the originally infected forms. In addition, lying free in the soil were 

 three pupce identical with the one obtained from a liberated larva a few 

 days previously. 



During the last few days of April and beginning of May, the soil in 

 the flower-pots containing the rest of the larvae was carefully and systemati- 

 cally searched with the aid of a large hand magnifier, and no pupae were 

 obtained. Nor did any of the larva? living show signs externally of 

 containing a maggot. 



The four pupae were preserved in a shallow glass vessel in a thin layer 

 of loose soil, and covered by a glass plate. The soil was kept very slightly 

 moist and exposed to the warmth of the sun from time to time. 



On 23rd May, exactly one month after the first pupa was obtained, a 

 fly hatched out, and on the following day the hatching of other two took 

 place. These were placed alive in a wide test-tube along with some grass 

 and a slice of potato. They are exceeding active flies. They flew 

 energetically about the tube, ran up and down upon the grass, brushed their 

 wings and heads with their feet, and generally groomed themselves in a 

 perfectly healthy manner. Meantime their structural features were noted 

 and the species identified as Bucentes geniculatus, De Geer. It was hoped 

 that the flies might live for some time, and that it would be possible to 

 observe their habits. One, however, died on the 24th. Meantime 

 endeavours were maintained to provide suitable food for the others, and 

 as the species is known as a frequent visitor to a considerable number of 

 flowers, various flowers rich both in pollen and nectar were placed beside 

 the flies, but while they ran about upon these, they were never seen to 

 feed, although a good deal of time was spent watching their movements 

 closely. 



One of the most striking features about these flies is their proboscis, 

 which is very long and bent upon itself like the blade and handle of a clasp- 

 knife. This they were frequently seen to unfold and stretch in front of 



