The Cambridge natural history, Vol. 10 (of 10)Beddard, Frank E. (Frank Evers)
Science
The Cambridge natural history, Vol. 10 (of 10)
Beddard, Frank E. (Frank Evers)
Animals; Mammals
The Aard Vark (earth-pig), genus _Orycteropus_, is characterised by its
heavy build, the body being covered by rather coarse and not very abundant
hair; the snout is long and pig-like, with round nostrils at its end; the
ears are long, erect, and pointed; the tail is very thick at first, so that
it has been aptly described as "a tapering of the body to a point." The
fore-limbs are four-toed, the hind five-toed.
[Illustration]
FIG. 107.--Aard Vark, or Cape Anteater. _Orycteropus capensis._ x 1/16.
In the skull there is a complete though slender zygoma; the premaxillaries,
though small, are not so rudimentary as in the American Edentates. The
annular tympanic is not ankylosed to the surrounding bones, a character
found in other low mammals. Contrary to what is found in _Manis_,
_Orycteropus_ has a huge lachrymal. There are thirteen dorsal and seven
lumbar vertebrae. The clavicle is well developed. _Orycteropus_ is peculiar
among Edentates in that the ischia do not unite with the vertebral column.
The femur has a third trochanter.
As mentioned on p. 162, the Aard Vark is diphyodont like normal mammals.
The permanent teeth consist of five molars and premolars on each side of
each jaw; the first two of these are premolars, and are simpler in their
form than the succeeding two teeth, which are partly divided by a median
furrow into two halves. These teeth are also peculiar in that they consist
entirely of vaso-dentine. They have been compared in minute structure to
those of the Ray _Myliobates_. According to Mr. Oldfield {188} Thomas[115]
there are seven milk teeth on each side of the upper jaw (limited to the
maxillae, and thus not incisors). An eighth tooth was discovered on one
side of one of the specimens examined by Thomas. In the lower jaw there are
only four milk teeth on each side. It is interesting to note that the
histological structure of these milk teeth agrees with that of the
permanent teeth. There are two species of this genus found in Africa: the
southern, _O. capensis_, is more hairy than the northern, _O. aethiopicus_.
_O. gaudryi_ is a Pliocene species from the Island of Samos and from
Persia, described by Dr. Forsyth Major and Dr. Andrews.[116] It closely
resembles the existing _O. aethiopicus_.
[Illustration]
FIG. 108.--Section of lower jaw with the teeth of _Orycteropus_. x 2.
(After Owen.)
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