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The skull.

The skull of the Indian Elephant.

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they are more than two years old; in one of them (c) there are
however in the maxillary bones still grooves from the lost dp2,
while such have disappeared from the other skull. In both skulls
the dps is in full wear, but the c?p 4 is only worn in its most anterior
part (in the upper jaw only the first plate is worn, in the lower jaw
a little more). We think the skulls belonged to animals of an age
of say 3—4 years.

e. About 48 cm long (the tusks, that are rather well developed
, not included); dps is shed, dp± is in full wear; the anterior
end of m1 projects on the skull but has been wholly covered by
the mucous membrane.

/. About 53 cm long; dpi somewhat more worn than in e,
the two anterior plates of ml have begun to be worn.

g. 71 cm long; dpi has been shed, m-^ is in full wear, m2
still in the alveolus.

h. 68 cm long; dpi is lost; m1 has been worn so much that
the anterior end has been worn away; m2 has just begun to be
worn.

i. k, I, all about 70 cm (69—73), have all shed m1 and wear m2.
m, the right half of the skull of the large Elephant from the

Zoological Gardens of Copenhagen named "Chang", about 50 years
old, wears m3, the posterior third of which was however still clothed
with the mucous membrane resp. enclosed in the alveolus.

To this material further come the head of the new-born Elephant
mentioned in the preface, that of the young Elephant mentioned
in the preface to the First part, and the head of "Chang", the
right half of which has been macerated, while the left half has been
prepared otherwise.

But few mammalian skulls have a more peculiar stamp than
that of the Elephants. This is a natural result of their being the
largest terrestrial Mammals — consequently animals with a relatively
small brain —, of their possessing a mightily developed, very
peculiar dental system, and their nasal cavity being also developed
in a very peculiar way. To this must still be added as a very
essential point the extraordinary weight of the head, which is as
we shall see, highly determining for its special forming.

The skull of the Elephant is to a prominent degree characterised
by the strong shortening and extraordinary increase in
height of all that part of the skull which is situated in the rear
of the infraorbital foramen; in older Elephants it may be rather
much higher than long; in relation to this high part the anterior
part, in which the tusks have their place, appears as little more
than a stately terminal outgrowth. Also the breadth is considerable,
in old Elephants not much less than the length. Surprising is
also the considerable height of that part of the skull which lies
below the zygoma; while in most Mammals the zygoma is not
situated much higher up than the cheek-teeth series, the distance
is in older Elephants considerable. The nasal cavity has in old
Elephants an almost perpendicular position through the skull; the
nasal bones are extraordinarily shortened. The orbita has in old
Elephants been moved so far forwards that the anterior margin
of it is situated before the osseous nasal aperture; in young Elephants
the orbita lies laterally to the same aperture. The temporal
groove is in old Elephants a mighty lateral concavity extending
far upwards and far inwards, its deepest point being not too
far distant from the median plane, deeply hollowing the side of
the skull. In old Elephants the molar tooth has its place below
the temporal groove, in strong contradistinction to what is found
in most Mammals. Bony crests for origin of muscles are so to
say not developed, but on the middle part of the posterior side
of the skull there is a deep indent, in which the mighty ligamen-
tum nuchse is inserted; in the middle of this indent there is a
thin leaflike prominent vertical crest.

From these general orientating remarks we proceed to the
more detailed treatment. We do not intend to give a full "description
" of the skull but only an exposition of what appears to
us to be of special interest concerning the skull of the Indian Elephant
and its development after the birth.

The intermaxillary bone of the Mammals (PL 40 fig. 3) consists
of three elements: pars dentalis in which the incisors are
implanted; processus palatinus lying on the medial side of the
fissura palatina; and a pars ascendens bordering the external bony
nasal opening and adjoining the nasal bone, the intermaxillary
bone otherwise only having connection with the maxillary bone.
The pars dentalis is commonly somewhat thickened, compared with
its posterior continuation, the proc. palatinus. We may on the pars
dentalis distinguish (PI. 40 fig. 3) an oblique anterior surface, and

a posterior surface, proceeding more or less obliquely downwards
to the proc. palatinus. The anterior end of the septal cartilage
lies in a furrow, excavated on the posterior surface in the
line where the two intermaxillaria meet.

In the Elephant (PL 40 fig. 4, and passim) the oblique anterior
surface has been quite extraordinarily developed, a consequence
of the mighty development of the incisors imbedded in the pars
dentalis. The said surface has been converted to an extended,
excavated plane, the upper (posterior) end of which has been
strongly raised; the posterior surface of the pars dentalis has
taken a perpendicular direction.

The only Mammal, in which a similar development of this
part is found, is the Dugong (PL 33 fig. 7), where the said anterior
surface is also very extended and where the posterior surface of
the pars dentalis has a direction, not as usual backwards, but
decidedly forwards. As in the Elephant the root-end of the incisors
is found at the superior margin of the anterior surface.

In Phocama (and other Toothed Whales) the bony exterior
nasal openings are as in the Elephant situated far back on the
upper side of the skull, and the anterior part of the skull, before
the nasal openings, forms in both as it were a "rostrum" of the
skull. But these likenesses are quite superficial:

In the Elephant the real exterior nares are lying far forward,
on the end of the trunk that represents the anterior part of the
nasal tubes, which are extraordinarily elongated; in this elongated
part there is no bony tissue developed on the upper side, the nasal
bones being very shortened. Also the septal cartilage has been
extraordinarily shortened, only the posterior part of the nasal tubes,
which is surrounded by bones, being endowed with it. But withal
the nasal cavity is intact, even peculiarly well developed.

In Phocama on the contrary the exterior nares have really
retired upon the upper side of the head, have even been pulled
far back, and thus the whole anterior part of the nasal cavity,
that part which otherwise lies above the intermaxillary and maxillary
bones and is separated in two tubes by the cartilaginous
septum, has totally disappeared, has been wiped out, and the inter-
maxillaries, maxillaries, palatines and vomer along with the cartilaginous
nasal septum have been put together into one coherent
mass (PL 30 fig. 9—15; comp. fig. 8), in the middle of which the
cartilage has its place: the bony lateral walls of the nasal cavity
have collapsed, embracing the nasal septal cartilage, which has
been preserved in good state and reaches the upper surface of the
rostrum, being jammed in between the right and left lateral wall.

The rostrum, i. e. that part of the skull which lies in front
of the nasal opening, thus is a totally different thing in the Elephant
and in the Whales: In the Elephant it is a prolongation of
the most anterior part of the face, of the pars dentalis of the inter-
maxillaries, while the posterior part of the palate has become extremely
shortened — in Phocaena that part of the intermaxillaries
has not been lengthened at all, while the posterior part of the
palate has become much lengthened. Correspondingly in the Elephant
the cartilaginous septum does by no means extend into the
rostrum, while in Phocaena it forms a characteristic part of it1.

In a few other Mammals there may be observed a feeble
indication of such a pushing together of the intermaxillaries on
the sides of the cartilaginous septum, as is so strongly developed
in Phocaena. In the Tapir a not quite insignificant terminal part
of the septum is enclosed between the two intermaxillaries; it is
as if also here a small part of the nasal cavity were obliterated.
Also in the Manatee we have found the anterior part of the cartilaginous
septum jammed in between the two intermaxillaries,
coincident with the outer nares having moved somewhat upwards
on the upper side of the snout. In the Elephant it is only a quite
narrow anterior margin of the septum which is thus lying between
the two intermaxillaries, which together on the posterior
side of their pars dentalis form a furrow in which the margin
of the septum is let in; and similar conditions may also be traced
in other Mammals.

Another point which should in this connexion be emphasized
is the following.

In several Mammals with foreshadowing of a proboscis —
Saiga (PL 33 fig. 5, PL 34 fig. 2), Alces, Tapir etc. — the nasal
bones have been much shortened, as in the Elephant, and the
posterior border of the external bony nasal opening correspondingly
retired on the upper surface of the skull — the dorsal wall
of the nasal cavities being to a large extent soft —, there being
in this manner a certain resemblance to the case of the Elephant.

1 The only Mammal — as far as we know — besides the Whales, which presents
similar conditions as those described above for Phocaena, is the extinct Macraachenia,
which obviously was an amphibious creature, spending as the recent Hippopotamus a
large part of its time in water (comp. Ivar Sefve, Macrauchenia patagonica. in: Bull.
Geol. Inst, of Upsala Vol. 19 p. 5 ff., who also compares its skull with that of the Dolphins
), and the outer nares of which are very practically placed in the top of the
skull between the orbits. In this remarkable form the intermaxillary and maxillary
bones and presumably also vomer and septum nasi have united to one continuous
mass, which is apparently quite analogous to the rostrum of Phocaena.