manently separate: the tendency to a multiplication of the teeth; the presence of marsupial bones
in the skeleton, even where the marsupium itself is not developed; and the absence of a true
voice,—all manifest a departure from the high
development of the placental Mammalia, and an
approach to that of the oviparous Vertebrata in
general, and to that of the Reptilia in particular.
The Sub-class before us, though not to be compared with the Placentalia in the number of its members, contains animals differing widely from each other in the modifications of their structure, in their habits, and in the nature of the food whereby they are sustained. ‘They even exhibit analogies, more or less distinct, to the principal Orders of the great division we have already considered: thus the Opossums, in their opposible thumbs, seem to represent the Quadrumana, the little Myrmecobius the Insectivora, and the Kangaroos the Ruminantia; while more strongly drawn analogies exist between the Dasyuri (the "Zebra-wolf, native-devil," &c., of the Australian colonists) and the Carnivora, between the Phalangistæ and Petauri, and the Rodentia, and between the Duck-bill and Spiny ant-eater, and the Edentata. These, however, are not real affinities; the characters which distinguish the marsupial from the olacental animals, and which bind them together among themselves, being of greater importance than those in which they respectively resemble the Orders just enumerated.
It is remarkable that this division of Mammalia is almost entirely confined to one region of the globe, Australia, including New Guinea, and the islands immediately adjacent. An exception ex-
