In certain marsupials a fibro-cartilage is developed between the external malleolus and the astragalus, and its origin from the deeper fibres of the external lateral ligament of the ankle can be traced.
But in the Marsupials a communication is opened between the two Mullerian ducts, and in the Placentals they combine below with the rudimentary Wolffian ducts to form a single "genital cord.
The corpus callosum, which forms a sort of wide bridge connecting the two hemispheres of the cerebrum, is only fully formed in the Placentals; it is very rudimentary in the Marsupials and Monotremes.
In the seventh chapter of my Systematic Phylogeny of the Vertebrates I advanced the hypothesis that the Placentals form a single stem with many branches, which has been evolved from an older group of the Marsupials (Prodidelphia).
There is still greater advance when we come to the Mammals, though even here the minds of the Monotremes and of the stupid Marsupials remain at a low stage.
While the Marsupials retain a great part of the characteristics of the Monotremes, they have also acquired some of the chief features of the Placentals.
Some are closely related to the Marsupials (especially the opossum).
The Marsupials are distinguished by a peculiar hook-like bony process that bends from the corner of the lower jaw and points inwards.
Moreover, all the Marsupials have teats on the mammary glands, at which the new-born animal sucks.
In all the other mammals (marsupials and placentals) a transverse partition is afterwards formed, and this separates the urogenital aperture in front from the anus-opening behind.
Even before this partition has been formed in the Marsupialsand Placentals, we see the first trace of the external sexual organs.
We may infer from this that the existing Marsupials are the remnant of an extensive earlier group that was distributed all over the earth.
This fundamental fact can be proved so easily at any moment from comparative anatomy that it has been universally admitted since the separation of the Placentals from the lower mammals (Marsupials and Monotremes).
The pouch, formed by a fold of the skin of the abdomen, in which marsupials carry their young; also, a pouch for similar use in other animals, as certain Crustacea.
A suborder of carnivorous and insectivorous marsupials including the dasyures and the opossums.
One of a group of marsupials including the phalangists.
A division of marsupials in which there are more fore incisor teeth in each jaw.
A group of marsupials which are partly insectivorous, as the opossum.
A group of Mammalia, including the marsupials and monotremes; -- so called because the corpus callosum is rudimentary.
A group of herbivorous marsupialsincluding the kangaroos and their allies.
Essay, the author does not make a separate section for such cases as the occurrence of fossil Marsupials in Europe (Origin, Ed.
America; and if fossil Edentata, Marsupials and monkeys were to be found in Tierra del Fuego, it would not make this district more truly S.
I do not mean to say that, for instance, the present Marsupials of Australia or Edentata and rodents of S.
As geology destroys geography we cannot be surprised in going far back we findMarsupials and Edentata in Europe: but geology destroys geography.
Nor can it be pretended that it is an immutable law that marsupialsshould have been chiefly or solely produced in Australia; or that Edentata and other American types should have been solely produced in South America.
Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely allied to the living marsupials of that continent.
Even the marsupials in Australia produced a species (Diprotodon) as large as a rhinoceros with a skull three feet long.
In elevating the marsupials to the rank of a sub-class the name Metatheria has been suggested as the title for the higher grade, with Marsupialia as the designation for the single order by which they are now represented.
Here may be noticed three genera of large extinct marsupials from the Pleistocene of Australia whose affinities appear to ally them to the wombat-group on the one hand and to the phalangers on the other.
The origin and evolution of the Australian marsupials have been discussed by Mr B.
The third and last sub-order of marsupials is the Diprotodontia, which is exclusively Australasian and includes the wombats, koala, cuscuses, kangaroos and their relatives.
Wallace, this author is of opinion that marsupials did not effect an entrance into Australia till about the middle of the Tertiary period, their ancestors being probably opossums of the American type.
The occurrence in the Santa Cruz beds of Patagonia of fossil marsupials allied to the living Caenolestes has been mentioned above.
It will be observed from the figures of the lower jaws, which are in most cases the only parts known, that in many instances the number of cheek-teeth exceeds that found in modern marsupials except Myrmecobius.
In addition to this replacement of a single pair of functional teeth in each jaw, it has been discovered that marsupials possess rudimentary tooth-germs which never cut the gum.
The larger Marsupials like the kangaroos are eminently saltatory, and the others are active in locomotion.
In Marsupials the scrotum is in front of the penis, but really in the same position as in other Mammals--that is, in front of the ventral part of the pelvic girdle.
This could scarcely be the case in the Marsupials in which the foetus when born is quite minute.
The actual development of the milk glands in Marsupials has been described by Bresslau [Footnote: Stuttgart, 1901.
There are fossil remains of Marsupials showing that in past ages creatures of this kind existed which were as large as elephants.
The young of the Marsupials are brought forth, or born, in an imperfect condition, and undeveloped in size and strength.
From Owen's observations on the Marsupials it is clear that the yolk-sack in this group plays an important, if not the most important part, in absorbing the maternal nutriment destined for the foetus.
The first American marsupials were Stephen Girard, Mr. Aston and the opossum; the principal marsupials of the Southern Hemisphere are Mr. Rhodes, and the kangaroo.
No one will suppose that the marsupials still remained androgynous, after they had approximately acquired their present structure.
One of these he devotes to man; in another he places both the marsupials and the Monotremata; so that he makes man as distinct from all other mammals as are these two latter groups conjoined.
In the mammalian class the males possess rudiments of a uterus with the adjacent passage, in their vesiculae prostaticae; they bear also rudiments of mammae, and some male Marsupials have traces of a marsupial sack.
The Marsupials stand in many important characters below the placental mammals.
I am informed by Mr. Gould that this holds good in a marked manner with the marsupials of Australia, the males of which appear to continue growing until an unusually late age.
The marsupialslingered along into the early stages of this period, and then disappeared from Europe.
In the preceding epoch marsupials only were represented.
In most other Marsupials it is very long, having sometimes as many as thirty-five vertebrae in the prehensile-tailed opossums.
In the remaining marsupials the second and third metacarpals and digits are very slender, and are enclosed within a common integument.
But, however much they may differ from one another, the skulls of all Marsupials agree in the following respects.
The skulls of the various types of the Marsupials frequently bear a strong superficial resemblance to those of some of the different groups of placental mammals.
The skull of Notoryctes is strongly suggestive of that of an Insectivore, and that of other Marsupials such as the wombat, recalls equally the characteristic features of a Rodent's skull.
The skull of the extinct Thylacoleo differs from that of all otherMarsupials in the fact that the postorbital bar is complete.
The lowest Marsupials as regards the ossicles are the Peramelidae, whose ossicles are of a frail papery consistence.
On the assumption that these functional teeth correspond to the milk-series of placentals, marsupials in this respect agree exactly with modern elephants, in which the same peculiarity exists.
A wide interval seems to separate these intelligent mammals from the lower placentals, the marsupials and monotremes.
The marsupials of Australia and Polynesia are generically distinct from all other animals on the globe except the opossum.
For instance, where the marsupials now live, there lived marsupials in ages long before Noah, as the fossil remains testify.
The fossils are fossil marsupials, but marsupials of species now extinct.
It is quite true that in a good manymarsupials this pouch is wanting.
The Marsupials seem almost to mimic the forms of ordinary quadrupeds.
One of the herbivorous marsupials is the Great Kangaroo, Macropus.
The Araucarian pines, which are now abundant in Australia and its islands, together with marsupial quadrupeds, are found in like manner to have accompanied the marsupials in Europe during the Oolitic period (see Figure 348).
Such an inference as to the wide geographical range of the ancient marsupials has been confirmed by the discovery in the Trias of North America of the above-mentioned Dromatherium.
The top of this fissure must have communicated with the bed of the Triassic sea, and probably at a point not far from the ancient shore on which the small marsupials of that era abounded.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "marsupials" in a variety of sentences. We hope that you will now be able to make sentences using this word.
