254 J. L. Bonhote: 



It is generally assumed that a large percentage of hybrids 

 belong to the male sex. This arises from two causes. 



(1) Among the Game Birds and Ducks, where hybrids hare 

 been most frequently noticed, the males have fine and distinct 

 plumages, whereas the females are all dull coloured and 

 resemble each other more or less closely, so that although a 

 male hybrid would be at once recognized, the females 

 would often be passed over. 



(2) There is a considerable mortality among the females. 

 As a rule, when full broods are reared, the sexes are about 

 in equal proportions, but if only a small proportion of the 

 brood reach maturity there is a large preponderance of 

 males. In the full broods the proportion of females was 

 48 per cent, as against 25 per cent, in the small broods, 

 and when we take into account that only one Duck in 

 three rears a full brood, the preponderance of males is 

 easily accounted for. My experiments, however, clearly show 

 that at birth the sexes among hybrids are nearly equal in 

 numbers, and in that respect do not differ from species when 

 bred pure. 



Among the first generation of the Piiitail-Mallard- 

 Spotbill trigens there is moreover a curious fact in relation 

 to sex and colour, although as yet its meaning is somewhat, 

 obscure. 



If the brood be small and only contain the light form 

 they will probably all be males ; if it contains both light and 

 dark forms we may expect light males and dark males and 

 light females, but there will pretty certainly be no light 

 females unless there be also some dark males, and females of 

 the light form will be present before females of the dark form. 

 In other words the various forms of Pintail trigens will 

 probably be produced in the following order, viz., (1) light 

 males, (2) dark males, (3) light females, (4) dark females, and 

 in a mixed brood the dark males would not appear before the 

 light males, or the light females before the darK males and 

 so on. I would not, however, lay too much stress on this fact 

 as it needs further corroboration in other crosses. 



III. Colour of the Eggs. 

 In the pure species the colour of the eggs in the Pintail 



