Origin of Species Variorum

↑ 5 blocks not present in 1859 1860 1861 1866 1869; present in 1872

The Ungulata or hoofed quadrupeds are now divided into the even-toed or odd-toed divisions; but the Macrauchenia of S. America connects to a certain extent these two grand divisions. No one will deny that the Hipparion is intermediate between the existing horse and certain older ungulate forms. What a wonderful connecting link in the chain of mammals is the Typotherium from S. America, as the name given to it by Professor Gervais expresses, and which cannot be placed in any existing order. The Sirenia form a very distinct group of mammals, and one of the most remarkable peculiarities in the existing dugong and lamentin is the entire absence of hind limbs, without even a rudiment being left; but the extinct Halitherium had, according to Professor Flower, an ossified thigh-bone "articulated to a well-defined acetabulum in the pelvis," and it thus makes some approach to ordinary hoofed quadrupeds, to which the Sirenia are in other respects allied. The cetaceans or whales are widely different from all other mammals, but the tertiary Zeuglodon and Squalodon, which have been placed by some naturalists in an order by themselves, are considered by Professor Huxley to be undoubtedly cetaceans, "and to constitute connecting links with the aquatic carnivora."

↑ 1 blocks not present in 1859 1860 1861 1866; present in 1869 1872

Another distinguished palæontologist, M. Gaudry, shows that very many of the fossil mammals discovered by him in Attica connect in the plainest manner existing genera.

→ Palæozoic animals, though belonging to the same orders, families, or genera with those living at the present day, 1860 1861

palæozoic animals, though belonging to the same orders, families, or genera with those living at the present day, 1859

although palæozoic animals can certainly be classed under existing groups, yet that at this ancient period these groups 1866

→ at this early epoch limited in such distinct groups 1859 1860 1861

so distinctly separated from each other 1866

→ are. 1859 1860 1861

are at the present time. 1866

→ living 1859 1860 1861 1866 1869

any two living 1872

→ groups. 1859 1860 1861 1866 1869

groups of species. 1872

→ the 1859 1860 1861 1866 1869

or groups, the 1872

→ I apprehend that 1859 1860 1861 1866

OMIT 1869 1872

→ would have to 1859 1860 1861 1866

certainly 1869 1872

→ from each other 1859 1860 1861 1866

OMIT 1869 1872

→ of the same two groups would be distinguished 1859 1860 1861 1866

are separated 1869 1872

→ quite distinct, at that period made some small 1859 1860 1861 1866

quite distinct, made at that period a somewhat nearer 1869

made a somewhat nearer 1872

→ other. 1859 1860 1861 1866 1869

other than they now do. 1872

wide

interval

difference

between the pig and the camel. ↑ ↑ In regard to the Invertebrata, Barrande, and a higher authority could not be named, asserts that he is every day taught

that,

that

→Palæozoic animals, though belonging to the same orders, families, or genera with those living at the present day, were not →at this early epoch limited in such distinct groups as they

~~now~~

now

→are.

Some writers have objected to any extinct

species,

species

or group of

species,

species

being considered as intermediate between →living

species,

species

or →groups. If by this term it is meant that an extinct form is directly intermediate in all its characters between two living

forms

forms,

→the objection is

~~probably~~

probably

valid. But →I apprehend that in a

~~perfectly~~

perfectly

natural classification many fossil species →would have to stand between living species, and some extinct genera between living genera, even between genera belonging to distinct families. The most common case, especially with respect to very distinct groups, such as fish and reptiles, seems to be,

that,

that

supposing them to be distinguished at the present day →from each other by a

score of

dozen

characters, the ancient members →of the same two groups would be distinguished by a somewhat lesser number of

characters;

characters,

so that the two

groups

groups,

~~though~~

though

formerly →quite distinct, at that period made some small approach to each →other.

It is a common belief that the more ancient a form is, by so much the more it tends to connect by some of its characters groups now widely separated from each other. This remark no doubt must be restricted to those groups which have undergone much change in the course of geological ages; and it would be difficult to prove the truth of the proposition, for every now and then even a living animal, as the Lepidosiren, is

dis- covered

discovered

having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and