of the Oil Beetle, Meloe. 305 



season. Goedart found the eggs of M. proscarabceus, deposited on the 12th 

 of May, produce larvae on the 23rd of June, a period of forty-three days ; 

 while DeGeer shows that eggs deposited by this species on the 1 8th of May 

 produced young on the 19th of June, a period of only thirty-three days. In 

 the packets of eggs watched by myself, I have found a much greater dif- 

 ference in the time of evolution. The first packet of eggs, obtained on the 

 8th of April 1 830, and inclosed in a tin box on the window-sill of my cham- 

 ber, were developed early on the morning of the 25th of May, a period of 

 forty-seven days ; while another packet, deposited by the same species, 

 M. violaceus, on the 26th of April 1 842, produced young on the 2nd of June, 

 a period of thirty-three days. From other eggs deposited by M. proscarabceus 

 on the 29th of April, the larvae came forth on the 3rd of June, a period of 

 only thirty-six days. In another instance, from a packet of eggs deposited on 

 the evening of the 1st of May, some of the larvae came forth on the 3rd of June, 

 or at thirty-four days ; while the greater number of them did not come forth 

 until the 5th, and a few remained until the 6th. Those of another brood, 

 deposited on the 30th of April, and placed under precisely the same circum- 

 stances in regard to locality and temperature as the last, also made their 

 appearance on the 6th of June. On the other hand, larvae were produced on 

 the 14th of June from a packet of eggs that were deposited on the 24th of 

 May, an interval of only twenty-one days. During this latter period the 

 temperature of the atmosphere was very much higher than in the earlier part 

 of May and April, and ranged from 70° Fahr. upwards. On the 13th of June, 

 the day before the larvae came forth, it was as high as 81° Fahr. 



From these facts we may conclude that the average period of the egg is 

 from four to five weeks ; but that the evolution of the embryo is accelerated 

 or retarded by the higher or lower temperature of the season. 



When the embryo is fully developed, the egg-shell is burst at its largest 

 extremity, and a little hexapod larva, an active, diminutive creature, that has 

 long been the subject of discussion, gradually withdrawing from its foetal 

 envelopes, presents itself to view as the progeny of Meloe. 



So exceedingly dissimilar in every respect is this microscopic and agile 

 little being to its heavy-bodied, slow-moving parent, that we can hardly be 

 surprised that those who have not actually witnessed its evolution from the 



