Miscellaneous. 195 



A single entrance-gate and a single passage thus correspond to 

 several distinct domiciles. 



It is especially at night that these digging labours for the excava- 

 tion of the cells and the boring of new galleries are performed. A 

 cone of fresh earth raised on the threshold of the orifice of the 

 passage bears witness every morning to the nocturnal activity, and 

 by its size proves that several Hymenoptera have participated in the 

 work. 



The cells of the Halicti consist of oval excavations, narrowed into 

 a neck at the upper part. Their walls are varnished with a water- 

 proof coating, which adds to the delicate polish of the chamber and 

 protects the interior from the invasion of damp. This varnish is of 

 the same nature as the goldbeater's-skin-like substance with which 

 the Colletce line their galleries and construct their little honey-bags. 

 Every thing tends to prove that this product of the two types of 

 Hymenoptera is of salivary origin, and may be compared to the 

 mucosity which certain birds, such as the swift and the salangane, 

 introduce into the construction of their nests. 



For the Halicti September is solely the month of amours. Then 

 the males, whose number exceeds that of the females, dance inces- 

 santly over the burrows and make their way into the passages. The 

 females remain in retirement in their cells or in the galleries, and 

 the copixlation takes place underground. When the first chills of 

 November arrive all the males have disappeared ; and the females, 

 which are then fertilized, pass the winter enclosed in their cells. 



Towards the month of May the females, fertilized in the autumn, 

 issue from their burrows and work at the nest in the absence of all 

 males, whose assistance, however, is none the less real because it has 

 preceded the oviposition by six months. 



In July a second generation is produced, without the presence of 

 any males ; but this time the want of cooperation of one of the 

 sexes is no longer an appearance, but a reality placed beyond doubt 

 by the continuity of the observations. 



Two months later males and females are produced from this 

 generation of a single sex. Fecundation takes place underground ; 

 the males perish ; the females hibernate ; and the same order of 

 things recommences. 



Thus the Halicti have two generations yearly : — one in the spring, 

 sexual, proceeding from mothers which, having been fertilized in 

 the autumn, have passed the winter in their cells ; the other, sestival, 

 due to parthenogenesis. From the concourse of the two sexes 

 females alone are produced; from parthenogensis originate both 

 males and females. 



From this it seems probable that other insects with several ovi- 

 positions in the year may possess the double mode of reproduction 

 of the Halicti ; but, with the exception of the Aphides, the partheno- 

 genesis of which has so long been known, what are these insects ? 

 and if there are such, do they confirm the suspicions to which the 

 Halicti give rise ? This the author proposes to investigate. 



