watch over the young when hatched (Cranilabrus massa, Cranilabrus melops). Often again it is the male who undertakes all the work. Thus the male of the Gasterosteus leiurus is incessantly occupied in fetching the young ones home, and driving away all enemies, including the mother.[1] The male stickleback, who is polygamous, builds a nest and watches with solicitude over the safety and rearing of the young.[2]
Many reptiles are unnatural parents; some, however, already possess some degree of familial instinct. Thus several males of the batrachians assist the female to eject her eggs. The male accoucheur toad rolls the eggs round his feet, and carefully carries them thus. The Surinam toad, the Pipa Americana, after having aided the female in the operation of laying the eggs, places them on the back of his companion, in little cutaneous cavities formed for their reception.[3]
The Cobra capella bravely defends its eggs. The saurians often live in couples, and the females of crocodiles escort their new-born little ones. Female tortoises go so far as to shelter their young in a sort of nest.[4]
But it is especially among birds and mammals that we find forms of union or association very similar to marriage and the family in the human species. Nothing is more natural; for anatomical and physiological analogy must of necessity lead in its train the analogy of sociology. There is no more uniformity either amongst mammals than amongst men; the needs, the habitat, and the necessities of existence dominate everything, and in order to secure adjustment to these, recourse is had to various processes.
Like men, birds live sometimes in promiscuity, and sometimes in monogamy or polygamy; the familial instinct is also very unequally developed among them. Sometimes even we find their conjugal customs modified by the kind of life they lead. Thus the wild duck, which is strictly monogamous in a wild state, becomes very polygamous when domesticated, and it is the same with the guinea fowl. Civilisation depraves these birds, as it does some men. As may be supposed, it is generally the animals living in
