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B.

THE FACIAL MUSCLES

OF

THE ELEPHANT.

1. SPHINCTER-PLATYSMA-GROUP.

PL 1.

In the material at our disposal, of this group of muscles
only the platysma and the auricular portion of the sphincter profundus
are present. Postponing the description of the latter muscle
to the auricular muscles, we shall in this place only treat of the
platysma.

From the median dorsal line of the occiput and the neck
there arises an aponeurosis; at its origin, thick, strong and containing
some elastic tissue. It extends down the side of the neck
where it gradually grows thinner and more fibrous, covers the
surface of the parotis and then turns on to the face, on the outside
of m. masseter (in PI. 1 somewhat of the aponeurosis has
been removed).

The fleshy part of platysma arises from this aponeurosis; it
extends upon the face and is divided into two rather well marked
portions, a mandibular portion and an angular portion.

The mandibular portion arises nearly in the middle of the
lateral face of the neck and forms a narrow ribbon-shaped muscle

*) In dissecting the facial muscles of the Elephant we have made some observations
relating to the skin and the hairs of the head, which may be recorded here.

The corium is of very different thickness on different parts of the head. It is
thickest postero-dorsally, between the ears; in the median line the corium is here
2 cm thick and very dense. Forward it gradually diminishes in thickness, but
still, in the median line between the eyes, the corium is 1 cm thick. The same
thickness is preserved as far as the base of the trunk, but then rapidly diminishes
distad over the trunk, so that the skin is soon only a couple of mm thick, and
towards the tip of the trunk it is scarcely one mm thick. Laterally and ventrally
on the head the thickness of the skin is, on the whole, somewhat less than dor-
sally ; in some places, for instance round the eye, the skin is much thinner than
in the surrounding parts. In most places the corium appears as a stratum, which
may be dissected off, and such is also the case on the trunk unto very near the
distal end; only in a few places, viz. in the tip of the trunk, in the inferior lip
and in the upper lip (from the angle of the mouth to a point a little in front of
the incisor) the corium forms a continuum with the underlaying muscular fascicles
and connective tissue.

As to the outer surface of the skin it is everywhere covered with small warts.
On' those parts, where the skin is thick, these warts are each furnished with a
thick horny layer (resembling a short obtuse spine), and groups of these warts
are here united into larger warts of different sizes, separated from the neighbouring
prominences by deep furrows.

The skin is furnished all over with hairs, which vary greatly in abundance. The
hairs for the most part project nearly at right angles to the surface. They are
mostly rather thick and rigid; their thickness is very variable. On the dorsal part

which turns on to the lower part of the face, covering the lower
part of m. masseter; its upper margin is continued in the part
of the aponeurosis which covers the rest of the masseter (omitted
in PI. 1). On the left side of the head the muscle is inserted outside
the lower jaw, in front of the masseter. On the right side
it divides into 3 branches, of which the inferior (PI. 1, a), rather
a broad one, is inserted outside the lower jaw, in front of masseter
; the second (PI. 1, b), somewhat narrower branch turns
a little upwards, thrusts itself under the lower part of m. bucci-
natorius, and is inserted into the lower jaw just below this
muscle; the uppermost branch (PI. 1, c) bends very much upwards
and forwards and joins the angular portion.

The angular portion arises from the aponeurosis on the outside
of the masseter. Behind the origin of the angular portion,
and above the mandibular portion, a rather considerable part
of the masseter thus remains free, covered only by the aponeurosis
. On the left side the angular portion forms a closely connected
muscle, which arises with 4 or 5 flat, broad portions; they
join a little behind the angle of the mouth, the bundles running
under each other and projecting into the m. buccinatorius. The

of the head they are thickest, on the under side of the trunk remarkably fine.
They may be rather long (5—7 cm), especially on the upper side of the head,
round the opening of the ear and on the upper and lower Hp, but most of the
hairs are short stubbles.

The hairs are found more closely arranged dorsally from behind to the root
of the trunk, but of a continuous hairy coat there is also here no question, there
being rather considerable distances (2—5 mm) between the individual hairs. On
the lateral aspect of the head (the cheek) they are more scattered, but become
more numerous along the margin of the lower jaw, and forward on the lower lip.
On the eyelids, especially the upper eyelid, there are some few hairs. Along the
margin of the upper eyelid the eyelashes are developed, which are numerous, long,
and stiff: and arranged in several series; along the lower eyelid they are shorter
and much less numerous. On the external ear there are hairs scattered along the
whole margin and single hairs on both surfaces; on the mediad surface they are
very fine. Round the entrance into the meatus the hairs are more dense.

Along the margin of the upper lip there are rather numerous hairs, of which
some look almost as though they were vibrissae; but they have no sinus round
them. On the lower lip there are some scattered long, thick and stiff hairs, which
are real sinus-hairs. Along the whole length of the trunk there are short, thin,
scattered hairs, most numerous on the dorsal and lateral sides. From about the
middle of the trunk to the distal end there appear between these, especially laterally
, some long and stiff hairs, which are surrounded with a well-developed
sinus. The digitiform prominence at the tip of the trunk is almost hairless, but
the ventral margin of the nasal opening is studded with scattered quite short stiff
hairs, round which we have found a small sinus.

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