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APPENDIX:

Descriptions of the facial muscles of various Ungulates.1)

1. CAMEL.

(Camelus bactrianus, young. — Dromedary.)
i. Platysma-sphincter-group.

PI. 5.

The sphincter superficialis is wanting, at all events on the head2).

The platysma forms a flat, continuous, rather full muscular
body, the bundles of which arise from an aponeurosis on the
dorso-lateral circumference of the neck and the occiput. The
bundles extend farther back (a little behind the parotis) in the
Camel than in the Dromedary (v. PL 5), in which they arise at
some distance in front of the salivary gland. The muscular body
stretches with longitudinal, slightly arched bundles on the
lower part of the face, reaching nearly half way up on the
masseter, the anterior end thrusting between the bundles of the
m. buccinatorius, at some distance behind, and below, the angle
of the mouth. In the Camel they do not extend quite so far as
in the Dromedary, where the anterior bundles pass obliquely upwards
, towards the lower lip. The muscular body is so broad
that it extends downwards, round the margin of the lower jaw,
from which several of the lower bundles take their origin. Upwards
the muscular body is continued in the form of a thin
fascia, which covers a great part of the m. masseter and the
other muscles of the face (in PI. 5 this fascia has been dissected off).

The pars zygomatica is completely separated from the rest
of the platysma. It is a broad and rather powerful muscle arising
with a flat well defined tendon from the arcus zygomaticus:
from the origin the bundles turn forwards in a slight arc, then
passing longitudinally straight forwards in the direction of the
angle of the mouth, thrusting, at some distance behind the latter,
between the bundles of the m. buccinatorius.

The sphincter profundus is present in the shape of two portions
quite separated from each other. The posterior, the auricular
portion, arises with a thin aponeurosis, outside the parotis;
the narrow, very thin and pale muscle inserts itself into the lateral
circumference of the basis of the auricle. The anterior portion
, the portio palpebralis, arises with a thin aponeurosis outside
the m. masseter and the m. buccinatorius, which is covered
by the platysma. The muscular body is flat, thin and rather narrow
, and its bundles converge dorsad thrusting between the bundles
of the m. orbicularis oculi of the lower eyelid.

*) The muscles of the external ear have not been included in these descriptions,
which on the whole make no claim of being exhaustive, but which we think will
nevertheless be of some use. They have been prepared for the sake of comparison
with the corresponding muscles of the Elephant.

2) Nor in the Lama, the whole neck of which we have examined, there is a
sphincter superficialis present. The neck of the Camel we have not had an opportunity
to examine.

2. Orbicularis-oculi-group

(PI. 5 and PI. 16, fig. 21)

is quite primitive in so far as the whole group forms a continuous
muscular plate in which no single muscle can be separated.

Round the eye is the m. orbicularis oculi, which consists
partly of circular fascicles, partly of fascicles that cross one another
behind the posterior angle of the eye (comp. the diagram
PL 16, fig. 21). The whole muscular mass is so broad that it
projects not a little beyond the margin of the bony orbita. It is
particularly broad in the lower eyelid — rather broader than in
the upper one — so that the fascicles which turn in an arc up
behind the posterior angle of the eye extend a considerable distance
behind this.

Posteriorly the orbicularis passes immediately into the m.
postorbiculaiis. In the young Camel which we examined, the
fascicles ran in a low arc dorso-ventrad, closely joining the
orbicular fascicles. In the Dromedary figured, PL 5 and PL 16,
these postorbicular fascicles are shorter, extending downwards
only along the orbicular fascicles of the upper eyelid, and interlocking
with the orbicular fascicles of the lower eyelid.

Anteriorly the orbicularis is continued directly in the m.
pro3orbicularis, which consists of fascicles that run in an arc from
the forehead downwards before the m. orbicularis, the curve corresponding
so exactly to that of the fascicles of this muscle that
no limit whatever can be found between them. The prseorbicular
fascicles spread like a fan downwards, thrusting themselves for
the most part between the fascicles of the m. buccinatorius.
Above the eye the prseorbicular fascicles are continued posteriorly
into a rather broad and flat muscular body, the m. supraorbicu-
laris. The fascicles of this muscle arise from an aponeurosis on
the frontal surface, run outwards, and a little forwards, and extend
downwards into the upper eyelid.

In front, the m. prseorbicularis passes immediately into the
m. nasolabialis, which forms a long and high, flat, muscular body
extending over the anterior part of the face. The fascicles,
which arise from an aponeurosis in the fronto-nasal region, run
obliquely forwards and downwards. Behind the angle of the
mouth they thrust themselves between the fascicles of the superficial
layer of the m. buccinatorius; whereas in front of this they
run into the upper lip. The origin of this muscle extends over
the whole dorsum of the nose and, in the anterior part, the fascicles
gradually take a more and more transverse direction, so
that they at last run transversely outwards to the dorsal circumference
of the nostril. A little behind this the muscular body
is pierced by a bundle of fibres from the m. maxillo-labialis,
which runs longitudinally above the nostril. (PL 5, comp. PL 11,
fig. 4.)