ct of
weakness and proceeds with decline. Some cases will be given below in
which incestuous marriages occur where the parties are unable to obtain
any other wives. Neglect of the incest taboo is rather a symptom than a
cause of group decline.

+514. Incest in ethnography.+ Martius says of the tribes on the
upper Amazon, in general, that incest in all grades is frequent
amongst them. In the more southern regions the taboo is stricter
and better observed. Amongst the former it is shameful for a man
to marry his sister or his brother's daughter. The usages are the
more strict the larger the tribe is. In small isolated groups it
frequently happens that a man lives with his sister. He heard of
two tribes, the Coerunas and the Uainumus, who observed little
rule on the subject. They were dying out.[1665] "Not seldom an
Indian is father and brother of his son."[1666] Effertz writes
that, amongst the Indians of the Sierra Madre, Mexico, incest
between father and daughter "is of daily occurrence," although
incest between brother and sister is entirely unknown. The former
unions are due to economic interest. The Indian tills small bits
of land scattered in the hills. He cannot exist without a woman
to grind corn for him. When he goes to a distant patch of land he
takes his daughter with him. He has but one blanket and the
nights are cold. If he has no daughter he must take another
woman, but then he must share his crop with her.[1667]

+515.+ The tribes of South Australia are "forbidden to have
intercourse with mothers, sisters, and first or second cousins.
This religious law is strictly carried out and adhered to under
penalty of death." The most opprobrious epithet for an opponent
in a quarrel is one which means a person who has sex intercourse
with kin nearer than second cousins.[1668] Some Dyaks are
indifferent to the conduct of their wives, and both sexes
practice sex vice, but they insist on drowning any one who
violates the taboo of incest.[1669] Other Dyaks (the Ot Danom)
have no notion of incest. The former are on the coast, the latter
inland. Hence it seems probable that the notion of incest came to
the Dyaks from outside.[1670] The Khonds practice female
infanticide, from a feeling that marriage in the same tribe is
incest.[1671] Cucis are allowed to marry without regard to
relationship of blood, except mother and s