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E.

THE NASAL CAVITY.

The part of the nasal tubes, which lies before (rostrad of)
the cartilaginous nose, and which is exceedingly short in other
Mammals, has in the Elephant been lengthened to the proboscis,
that is entirely composed of muscles, connective tissue and epidermis
; as „proboscis" we designate the entire anterior part of
the nasal tubes unto the anterior end of the nasal cartilaginous
wings.

In the free part of the proboscis, it is to say that part of it,
which is situated rostrad to the intermaxillary bones, the lumen
in each of the nasal tubes is nearly circular. But in that part
of it, which is attached to the upper side of the intermaxillary,
the lumen takes another form. In the section which is represented
in PI. 41 fig. 1 it is nearly triangular with a dorsal narrow
apex. Whilst in the free part of the proboscis the ventral
side of the wall is thicker than the dorsal and lateral, the ventral
wall becomes rather thin in the part fastened to the intermaxillary
, while the dorsal and lateral wall is much thickened;
in accordance with this the nasal canals in the longitudinal section
(PL 18—20) have in this place — directly before the anterior end
of the nasal cartilage — a downward flexion. Behind this segment
of the nasal tube, below the anterior end of the cartilaginous nasal
wings, the alteration of the lumen of the nasal tube is continued
(PL 41 fig. 2): the dorsal corner of fig. 1 becomes a fissure, which
finally extends below the cartilaginous nasal wings (figs. 3—4) and
laterally is bordered by a thick muscular cushion, in which is imbedded
a little separate oblong cartilage (fig. 4), to which we shall
come back later on. The cushion is richly supplied with strong
muscular bundles, which have partly a transverse direction, partly,
in the ventral portion of the organ, are bending downwards; they
arise from the intermaxillary, some of them from the skin; they
terminate in the mucous membrane, which invests the cushion.
Besides the muscular bundles there is also a large contingent of
connective tissue consisting partly of rather strong bundles, forming
a tough meshwork; many of the bundles have a transverse
direction. In the middle and in the ventral part of the cushion
the muscular bundles are predominant, while dorsally the cushion
apparently consists of connective tissue alone. The muscular bundles
in contracting evidently must considerably dilate the nasal canal;
at rest, the muscular bundles being relaxed, this part of the nasal
tube is only open ventrally, otherwise forming a collapsed fissure.

The part of the nasal canal which contains this muscular
cushion, ascends steeply on the anterior side of the intermaxillary
, to which it is firmly attached. Above the upper margin of
the intermaxillary the nasal tube is continued as a narrow flat
semilunar fissure below the posterior part of the cartilaginous

nasal wing; then it forms a sharp angle and is continued between
the posterior side of the intermaxillary and the anterior
(inferior) side of the nasal bone down into the bony nasal cavity,
which as a nearly perpendicular tube leads into the pharynx. The
muscular cushion is caudad continued in a prominent roll and
further in the peculiar cartilaginous fold in the perpendicular tube,
which will be described below. As this fold appears to be — as
we shall see — part of the nasoturbinal, the muscular cushion
should be determined as the anterior part of the nasoturbinal,
which has been developed in a special manner.

The part of the nasal tubes, which is surrounded by bone,
is caudad a spacious canal. But rostrad — towards the upper
end of the bony nasal cavity — the free room is as usual obstructed
by the turbinals, but in the Elephant in a special manner.

The maxilloturbinal is practically totally absent, only the basal
plate of the bony maxilloturbinal being left (as already mentioned
p. 89), forming part of the wall of the nasal tube; but nothing
of it is projecting into the space of the nasal tube.

The ethmoturbinals are as usual lodged above the lamina
transversalis; they are rather short; their free ends have not the
usual rostrad direction but are directed ventrad, at almost right
angles to the grinding surface of the molar; their special description
is reserved for the next chapter. Only the nasoturbinal is to
be nearer inspected here.

Before entering upon the description of the nasoturbinal of the
Elephant we shall make some remarks on that of other Mammals.

The nasoturbinal — we describe it first as it is when invested
with the mucous membrane — is the uppermost of the ethmoturbinals
. It is continued forwards much further than the others,
the anterior end lying near the anterior nares. The rostral part
of it is a narrow fold, which posteriorly swills to a thick and
prominent fold, from which a downward process may extend
into the opening of the sinus maxillaris (PL 36 fig. 8). From
this point hindwards it again becomes lower. The bony nasoturbinal
fills most of the structure described, also the downward
process. But a more or less extended portion of the thin
anterior part contains a cartilaginous crest, which is continuous
with the cartilage investing, more or less coherently, the anterior
part of the nasal cavity; this cartilaginous crest may partially
be disintegrated into small cartilaginous pieces enclosed in
the fold.

In the Elephant (PL 38 figs. 1—2, PL 31 fig. 5, etc.) the bony
nasoturbinal, placed as usual above the other ethmoturbinals, is
very shortened. From the side of it, adjoining the next ethmo-
turbinal, rises a bony projection (rather prominent in the great