340 THE STRUCTURE AND LIFE OF BIRDS cnap. 
order of birds ; it is found in various stages of develop- 
ment in the different species of the American Molothrus, 
a bird allied to our Starlings. One South American 
species (JZ. donariensis) always lay their eggs in other 
birds’ nests, and never sit upon them themselves, but 
the number of eggs laid in one nest is so great that it 
is impossible all can be hatched. They sometimes lay 
in old forsaken nests, or in a nest of the year where in- 
cubation has already begun, or before the building is 
finished, so that their eggs are covered by the thick 
lining and never hatch. Many are dropped upon the 
ground. The parents, too, will often peck holes in 
numbers of their own eggs. Sometimes several 
together set to work to build a nest for themselves, 
but it is clumsily constructed, and, as far as is known, 
is never made use of. Another species (Molothrus 
rufoaxillaris) is also parasitic and apparently not so 
foolish as the last mentioned, though not so accom- 
plished a parasite as the Cuckoo. Another South 
American species (Afoléthris badius) is probably never 
parasitic. But they sometimes go to the length of 
seizing another bird’s nest and building their own 
upon the top of it. All these interesting facts we 
owe to Mr. Hudson, who has carefully observed the 
two South American birds that have the cuckoo 
habit. 
In North America there is.a Molothrus rus which never 
_lays more than one egg in one nest. f 
In this genus, then, we see the instinct in its various 
stages of development. Molothrus badius is a pirate 
and nota parasite. Jf. bonariensis is foolishly prodi- 
gal of its eggs. M. rufoaxillaris shows a greater 
