The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny

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Didelphis marsupialis syn. D. cancrivora syn. Philander cancrivorus Identifier: evolutionofmanpo021879haec (find matches)
Title: The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny
Year: 1879 (1870s)
Authors: Haeckel, Ernst Heinrich Philipp August, 1834-1919
Subjects: Human evolution Embryology, Human Anatomy, Comparative
Publisher: New York : Appleton
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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esimple structure of the allantois (which does not as yetdevelop a placenta), with many other characters, have beeninherited by the Pouched Animals from Cloacal Animals.On the other hand, they have lost the independent coracoid.bone (os coracoideiim) attached to the shoulder girdle. Amore important step consists in the fact that a cloaca is nolonger formed; the cavity of the rectum, together with theanal opening, is separated by a partition wall from the urinaryand sexual opening (sinus urogenitalis). Moreover, allPouched Animals develop special nipples on the milk-glands,which are sucked by the young after birth. These nipplesproject into the cavity of a pouch, or marsupium, in theventral side of the mother. This pouch is supported by a couple of marsupial bones. In it the young, which are30 152 THE EVOLUTION OF MAN. born in a very imperfect condition, are carried by themother for a long time; until, in fact, they are completelydeveloped (Fig. 197). In the large Giant Kangaroo, which
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Fig. 197.—The Crab-eating Pouched Eat (Philander cancrivorus).female with two young in its pouch. (After Brehm.) A THE POUCHED ANIMALS AS ANCESTORS OF MAN. 153 attains the height of a man, the embryo develops in theuterus but for a month; it is then born in a very incompletecondition, and attains all its further development in themothers pouch, where, for about nine months, it remainsattached to the milk-glands. All these and other characters (especially the peculiarstructure of the internal and external sexual organs of themale and female) clearly show that the whole sub-class ofthe Pouched Animals (Marsupialia) are a single group,which originated from the promammalian branch. From abranch of these Pouched Animals (perhaps from severalbranches) the parent-forms of the higher Mammals, thePlacental Animals, afterwards sprang. Hence we mustreckon a whole series of Pouched Animals among the an-cestors of the human race; and these constitute the seven-teenth stage in the human pedigree.

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