species were invariably apterous, the males never so. In theLepidop- 

 tera the females of the two species of the genus Orgyia amongst the 

 Bombycidc'e were invariably apterous. So were the Psychidrc. 

 Amongst the Geometrae were the following genera the females of which 

 were entirely apterous, Phigalia and Myssia, and the following in 

 which the females were either entirely apterous or possessed wings only 

 partially developed, Hybernia (including five species), Anisopteryx 

 and Cheimatobia (two species). 



Another peculiarity of sex was that the males of many of the 

 Bombyces and Geometras had doubly pectinated antennae, whereas 

 those of the females were much less strongly pectinated, or were 

 merely simple and setiform. 



In the Genus Blatta, of the order Orthoptera, the females were 

 partially apterous. 



The differences of colour in the sexes were also very remarkable. 

 As a rule (to which, however, there were some striking exceptions) the 

 colours of the male were brighter, more beautiful, and more glittering 

 than those of the female. In the Genus Lyca;na, or Polydmmatus of 

 the Lepidoptera, the males were (with two exceptions out of lo species) 

 of beautiful shades of blue, whereas the females, with two exceptions 

 (in Argiolus and Arion), were of a dull brown. In Iris, as was well 

 known, the wings of the male were shot with splendid purple, but the 

 female was of a dull brown. 



One of the most notable exceptions to this rule occurred in Thecia 

 Qjiiercus, the males of which were dull purple throughout, whereas the 

 fore wings -of the female were enlivened by a patch of brilliant 

 blue. 



The butterflies copulated about noon in the brightest sunshine. 

 The crepuscular and nocturnal insects copulated at those times. 

 After copulation the male frequently died from exhaustion. 



The impregnation of the female produced the development of the 

 germs of the eggs lying on the tubes of her ovaries* After the de- 

 velopment of the egg was completed, the period for depositing it 

 arrived, which took place immediately, to make room for an 



* See a letter from M. Victor Andouin to M. Arago, in the "Annalesdes 

 Sciences Naturelles," July, 1824. 



