The History of Creation, Vol. 2 (of 2) / Or the Development of the Earth and its Inhabitants by the Action of Natural Causes - Ernst Haeckel

The name of pouched animals is given to the class on account of the purse-shaped pouch (marsupium) existing in most instances on the abdominal side of the female animals, in which the mother carries about her young for a considerable time after their birth. This pouch is supported by two characteristic marsupial bones, also existing in Cloacal animals, but not in Placental animals. The young Marsupial animal is born in a much more imperfect form than the young Placental animal, and only attains the same degree of development which the latter possesses directly at its birth, after it has developed in the pouch for some time. In the case of the giant kangaroo, which attains the height of a man, the newly born young one, which has been carried in the maternal womb not much longer than five weeks, is not more than an inch in length, and only attains its essential development subsequently, in the pouch of the mother, where it remains about nine months attached to the nipple of the mammary gland.

The different divisions generally distinguished as families in the sub-class of Marsupial animals, deserve in reality the rank of independent orders, for they differ from one another in manifold differentiations of the jaw and limbs, in much the same manner, although not so sharply, as the various orders of Placental animals. In part they perfectly agree with the latter. It is evident that adaptation to similar conditions of life has effected entirely coincident or analogous transformations of the original fundamental form in the two sub-classes of Marsupials. According to this, about eight orders of Marsupial animals may be distinguished, the one half of the main group or legion of which are herbivorous, the other half carnivorous. The oldest fossil remains of the two legions (if the previously mentioned Microlestes and the Dromatherium are not included) occur in the Jurassic strata, namely, in the slates of Stonesfield, near Oxford. The slates belong to the Bath, or the Lower Oolite formation—strata which lie directly above the Lias, the oldest Jura formation. (Compare p. [15].) It is true that the remains of Marsupials found in the slates of Stonesfield, as well as those which were found later in the Purbeck strata, consist only of lower jaws. (Compare p. [29].) But fortunately the lower jaw is just one of the most characteristic parts of the skeleton of Marsupials. For it is distinguished by a hook-shaped process of the lower corner of the jaw turning downwards and backwards, which neither occurs in Placental nor in the (still living) Cloacal animals, and from the existence of this process on the lower jaws from Stonesfield, we may infer that they belonged to Marsupials.

SYSTEMATIC SURVEY OF CLOACAL AND MARSUPIAL MAMMALIA.

I. First Sub-class of Mammalia: Forked or Cloacal Animals (Monotrema, or Ornithodelphia).
Mammals with Cloaca, without Placenta, with Marsupial Bones.

I. Primary Mammals Promammalia	Unknown extinct Mammalia from the Trias Period					(Microlestes?) (Dromatherium?)
II. Beaked Animals Ornithostoma	1.	Aquatic beaked animals	1.	Ornithorhynchida	1.	Ornithorhynchus paradoxus

II. Second Sub-class of Mammalia:
Pouched or Marsupial Animals (Marsupialia, or Didelphia).
Mammals without Cloaca, without Placenta, with Marsupial Bones.
Legions of Marsupialia.	Orders of Marsupialia.		Systematic Name of the orders.		Families of the Marsupialia.

III. Herbivorous Marsupial Animals Marsupialia Botanophaga	1.Hoofed Marsupial animals		1.	Barypoda	1.	Stereognathida
					2.	Nototherida
					2.	Diprotodontia
	2. Kangaroo Marsupial animals (Leaping pouched animals)		2.	Macropoda	4.	Plagiaulacida
					5.	Halmaturida
					6.	Dendrolagida
	3. Root-eating Marsupial animals (Gnawing pouched animals)		3.	Rhizophaga	7.	Phascolomyida
	4. Fruit eating Marsupial animals (Climbing pouched animals)		4.	Carpophaga	8.	Phascolarctida
					9.	Phalangistida
					10.	Petaurida
IV. Carnivorous Marsupial Animals Marsupialia Zoophaga	5. Insectivorous Marsupial animals Primæval pouched animals)		5.	Cantharophaga	11.	Thylacotherida
					12.	Spalacotherida
					13.	Myrmecobida
					14.	Peramelida
	6. Marsupial animals poor in teeth (Pouched animals with trunks)		6.	Edentula	15.	Tarsipedina
	7. Rapacious marsupial animals (Rapacious pouched animals)		7.	Creophaga	16.	Dasyurida
					17.	Thylacinida
					18.	Thylacoleonida
	8. Ape-footed Marsupial animals (Pouched animals with hands)		8.	Pedimana	19.	Chironectida
					20.	Didelphyida

SYSTEMATIC SURVEY OF PLACENTAL ANIMALS.

III. Third Sub-class of Mammalia:
Placentalia, or Monodelphia (Placental Animals).
Mammals without Cloaca, with Placenta, without Marsupial Bones.
Legions of the Placental Animals.	Orders of the Placental Animals.	Sub-orders of the Placental Animals.		Systematic Name of the Sub-orders.
III. 1. Indecidua. Placental Animals without Decidua.

V. Hoofed Animals Ungulata	I. Single-hoofed Perissodactyla	1.	Tapirs	1.	Tapiromorpha
	I. Single-hoofed Perissodactyla	2.	Horses	2.	Solidungula
	II. Double-hoofed Artiodactyla	3.	Pigs	3.	Choeromorpha
	II. Double-hoofed Artiodactyla	4.	Ruminating	4.	Ruminantia

VI. Whales Cetacea	III. Herbivorous Whales Phycoceta	5.	Sea cows	5.	Sirenia
	IV. Carnivorous Whales Sarcoceta	6.	Whales	6.	Autoceta
	IV. Carnivorous Whales Sarcoceta	7.	Zeuglodonta	7.	Zeugloceta

VII. Animals poor in teeth Edentata	V. Digging Animals Effodientia	8.	Ant-eaters	8.	Vermilinguia
	V. Digging Animals Effodientia	9.	Armadilloes	9.	Cingulata
	VI. Sloths Bradypoda	10.	Giant Sloths	10.	Gravigrada
	VI. Sloths Bradypoda	11.	Dwarf Sloths	11.	Tardigrada

III. 2. Deciduata. Placental Animals with Decidua.

VIII. Placental Animals. Zonoplacentalia	VII. Rapacious Animals Carnaria	12.	Rapacious land animals	12.	Carnivora
		13.	Rapacious sea animals	13.	Pinnipedia

	VIII. False-hoofed Animals Chelophora	14.	Hyrax	14.	Lamnungia
		15.	Toxodonts	15.	Toxodontia
		16.	Dinotheria	16.	Gonyognatha
		17.	Elephants	17.	Proboscidea

XI. Disc Placental Animals Zonoplacentalia	IX. Semi-apes Prosimiæ	18.	Fingered animals	18.	Leptodactyla
		19.	Flying lemur	19.	Ptenopleura
		20.	Long-footed	20.	Macrotarsi
		21.	Short-footed	21.	Brachytarsi

	X. Gnawing Animals Rodentia	22.	Squirrel species	22.	Sciuromorpha
		23.	Mouse species	23.	Myomorpha
		24.	Porcupine species	24.	Hystrichomorpha
		25.	Hare species	25.	Lagomorpha

	XI. Insect-eating Animals Insectivora	26.	With a Cœcum	26.	Menotyphla
		27.	Without a Cœcum	27.	Lipotyphla

	XII. Flying Animals Chiroptera	28.	Flying foxes	28.	Pterocynes
		29.	Bats	29.	Nycterides

	XIII. Apes Simiæ	30.	Clawed apes	30.	Arctopitheci
		31.	Flat-nosed	31.	Platyrrhinæ
		32.	Narrow-nosed	32.	Catarrhinæ

PEDIGREE OF THE MAMMALIA